// insertInWithin places before/after advice around a statement
func (wb *WithinBlock) insertInWithin(a ast.Stmt, w *Weave) string {
rout := ""
mName := grabMethodName(a)
// begin line
begin := wb.fset.Position(a.Pos()).Line - 1
after := wb.fset.Position(a.End()).Line + 1
// until this is refactored - any lines we add in our
// advice need to be accounted for w/begin
before_advice := formatAdvice(wb.aspect.advize.before, mName)
after_advice := formatAdvice(wb.aspect.advize.after, mName)
if before_advice != "" {
rout = w.writeAtLine(wb.fname, begin+wb.linecnt, before_advice)
wb.linecnt += strings.Count(before_advice, "\n") + 1
}
if after_advice != "" {
rout = w.writeAtLine(wb.fname, after+wb.linecnt-1, after_advice)
wb.linecnt += strings.Count(after_advice, "\n") + 1
}
for t := 0; t < len(wb.aspect.importz); t++ {
wb.importsNeeded = append(wb.importsNeeded, wb.aspect.importz[t])
}
return rout
}
func (c *compiler) VisitStmt(stmt ast.Stmt) {
if c.logger != nil {
c.logger.Println("Compile statement:", reflect.TypeOf(stmt),
"@", c.fileset.Position(stmt.Pos()))
}
switch x := stmt.(type) {
case *ast.ReturnStmt:
c.VisitReturnStmt(x)
case *ast.AssignStmt:
c.VisitAssignStmt(x)
case *ast.IncDecStmt:
c.VisitIncDecStmt(x)
case *ast.IfStmt:
c.VisitIfStmt(x)
case *ast.ForStmt:
c.VisitForStmt(x)
case *ast.ExprStmt:
c.VisitExpr(x.X)
case *ast.BlockStmt:
c.VisitBlockStmt(x)
case *ast.DeclStmt:
c.VisitDecl(x.Decl)
case *ast.GoStmt:
c.VisitGoStmt(x)
case *ast.SwitchStmt:
c.VisitSwitchStmt(x)
default:
panic(fmt.Sprintf("Unhandled Stmt node: %s", reflect.TypeOf(stmt)))
}
}
func (check *checker) multipleDefaults(list []ast.Stmt) {
var first ast.Stmt
for _, s := range list {
var d ast.Stmt
switch c := s.(type) {
case *ast.CaseClause:
if len(c.List) == 0 {
d = s
}
case *ast.CommClause:
if c.Comm == nil {
d = s
}
default:
check.invalidAST(s.Pos(), "case/communication clause expected")
}
if d != nil {
if first != nil {
check.errorf(d.Pos(), "multiple defaults (first at %s)", first.Pos())
} else {
first = d
}
}
}
}
func emitTraceStmt(f *Function, event TraceEvent, syntax ast.Stmt) Value {
t := &Trace{
Event: event,
Start: syntax.Pos(),
End: syntax.End(),
Breakpoint: false,
syntax: syntax,
}
return emitTraceCommon(f, t)
}
func (p *parser) makeExpr(s ast.Stmt) ast.Expr {
if s == nil {
return nil
}
if es, isExpr := s.(*ast.ExprStmt); isExpr {
return p.checkExpr(es.X)
}
p.Error(s.Pos(), "expected condition, found simple statement")
return &ast.BadExpr{s.Pos()}
}
func (v *visitor) wrapLoop(node ast.Stmt, body *ast.BlockStmt) (block *ast.BlockStmt, loop ast.Stmt) {
block = astPrintf(`
{
scope := %s.EnteringNewChildScope()
_ = scope // placeholder
godebug.Line(ctx, scope, %s)
}`, v.scopeVar, pos2lineString(node.Pos()))[0].(*ast.BlockStmt)
block.List[1] = node
loop = node
return
}
func (f *File) validStmt(stmt ast.Stmt) *Error {
if stmt == nil {
return nil
}
if assign, ok := stmt.(*ast.AssignStmt); ok {
if len(assign.Lhs) != 1 || len(assign.Rhs) != 1 {
return &Error{errors.New("Invalid assigment statment"), assign.Pos()}
}
return nil
}
if ifstmt, ok := stmt.(*ast.IfStmt); ok {
if err := f.validExpr(ifstmt.Cond); err != nil {
return err
}
// initialization clause not allowed for if statements
if ifstmt.Init != nil {
return &Error{errors.New("ifstmt cannot have initialization clause"), ifstmt.Init.Pos()}
}
if err := f.validStmt(ifstmt.Body); err != nil {
return err
}
if err := f.validStmt(ifstmt.Else); err != nil {
return err
}
}
if blk, ok := stmt.(*ast.BlockStmt); ok {
for _, s := range blk.List {
if err := f.validStmt(s); err != nil {
return err
}
}
}
if _, ok := stmt.(*ast.EmptyStmt); ok {
return nil
}
if ret, ok := stmt.(*ast.ReturnStmt); ok {
if ret.Results == nil || len(ret.Results) == 0 {
return nil
}
if len(ret.Results) > 1 {
return &Error{errors.New("Return statement doesn't allow multiple return values"), ret.Pos()}
}
return f.validRetExpr(ret.Results[0])
}
if indec, ok := stmt.(*ast.IncDecStmt); ok {
// TODO specialize
if err := f.validExpr(indec.X); err != nil {
return err
}
}
return &Error{errors.New(fmt.Sprintf("Invalid stmt:%v", stmt)), stmt.Pos()}
}
func generateCheckedAssign(stmt ast.Stmt, place ast.Expr) ast.Stmt {
pos := stmt.Pos()
return &ast.IfStmt{
If: pos,
Init: stmt,
Cond: &ast.BinaryExpr{
X: place,
OpPos: pos,
Op: token.NEQ,
Y: ast.NewIdent("nil")},
Body: &ast.BlockStmt{
Lbrace: pos,
List: []ast.Stmt{&ast.ReturnStmt{}},
Rbrace: pos},
}
}
func (v *ShortError) VisitStmt(scope *ast.Scope, stmt ast.Stmt) ScopeVisitor {
v.stmt = stmt
switch stmt := stmt.(type) {
case *ast.BlockStmt:
return &ShortError{v.file, v.patches, v.stmt, stmt, 0, new([]byte)}
case *ast.ExprStmt:
if call := calltomust(stmt.X); call != nil {
// TODO(elazarl): depends on number of variables it returns, currently we assume one
pos := v.file.Fset.Position(stmt.Pos())
fmt.Printf("%s:%d:%d: 'must' builtin must be assigned into variable\n",
pos.Filename, pos.Line, pos.Column)
}
case *ast.AssignStmt:
if len(stmt.Rhs) != 1 {
return v
}
if rhs, ok := stmt.Rhs[0].(*ast.CallExpr); ok {
if fun, ok := rhs.Fun.(*ast.Ident); ok && fun.Name == MustKeyword {
if stmt.Tok == token.DEFINE {
tmpVar := v.tempVar("assignerr_", scope)
*v.patches = append(*v.patches,
patch.Insert(stmt.TokPos, ", "+tmpVar+" "),
patch.Replace(fun, ""),
patch.Insert(stmt.End(),
"; if "+tmpVar+" != nil "+
"{ panic("+tmpVar+") };"),
)
for _, arg := range rhs.Args {
v.VisitExpr(scope, arg)
}
return nil
} else if stmt.Tok == token.ASSIGN {
vars := []string{}
for i := 0; i < len(stmt.Lhs); i++ {
vars = append(vars, v.tempVar(fmt.Sprint("assgn", i, "_"), scope))
}
assgnerr := v.tempVar("assgnErr_", scope)
*v.patches = append(*v.patches,
patch.Insert(stmt.Pos(),
strings.Join(append(vars, assgnerr), ", ")+":="),
patch.InsertNode(stmt.Pos(), rhs.Args[0]),
patch.Insert(stmt.Pos(),
"; if "+assgnerr+" != nil "+
"{ panic("+assgnerr+") };"),
patch.Replace(rhs, strings.Join(vars, ", ")),
)
v.VisitExpr(scope, rhs.Args[0])
return nil
}
}
}
}
return v
}
func (t *rewriteVisitor) rewriteRecvStmt(stmt ast.Stmt) []ast.Stmt {
// Prohibit inner blocks from having channel operation nodes
switch q := stmt.(type) {
case *ast.AssignStmt:
for _, expr := range q.Lhs {
// TODO: Handle channel operations inside LHS of assignments
RecurseProhibit(t, expr)
}
for _, expr := range q.Rhs {
if expr == nil {
continue
}
// TODO: Handle channel operations inside RHS of assignments
if ue := filterRecvExpr(expr); ue != nil {
RecurseProhibit(t, ue.X)
} else {
RecurseProhibit(t, expr)
}
}
case *ast.ExprStmt:
if q == nil {
break
}
// TODO: Handle channel operations inside RHS of assignments
if ue := filterRecvExpr(q.X); ue != nil {
RecurseProhibit(t, ue.X)
} else {
RecurseProhibit(t, q)
}
default:
panic("unreach")
}
// Rewrite receive statement itself
return []ast.Stmt{
makeSimpleCallStmt("vtime", "Block", stmt.Pos()),
stmt,
makeSimpleCallStmt("vtime", "Unblock", stmt.Pos()),
}
}
// compiles a statement
func (w *World) compileStmt(st ast.Stmt) Expr {
switch st := st.(type) {
default:
panic(err(st.Pos(), "not allowed:", typ(st)))
case *ast.EmptyStmt:
return &emptyStmt{}
case *ast.AssignStmt:
return w.compileAssignStmt(st)
case *ast.ExprStmt:
return w.compileExpr(st.X)
case *ast.IfStmt:
return w.compileIfStmt(st)
case *ast.ForStmt:
return w.compileForStmt(st)
case *ast.IncDecStmt:
return w.compileIncDecStmt(st)
case *ast.BlockStmt:
w.EnterScope()
defer w.ExitScope()
return w.compileBlockStmt_noScope(st)
}
}
func (p *printer) stmt(stmt ast.Stmt, nextIsRBrace bool) {
p.print(stmt.Pos())
switch s := stmt.(type) {
case *ast.BadStmt:
p.print("BadStmt")
case *ast.DeclStmt:
p.decl(s.Decl)
case *ast.EmptyStmt:
// nothing to do
case *ast.LabeledStmt:
// a "correcting" unindent immediately following a line break
// is applied before the line break if there is no comment
// between (see writeWhitespace)
p.print(unindent)
p.expr(s.Label)
p.print(s.Colon, token.COLON, indent)
if e, isEmpty := s.Stmt.(*ast.EmptyStmt); isEmpty {
if !nextIsRBrace {
p.print(newline, e.Pos(), token.SEMICOLON)
break
}
} else {
p.linebreak(p.lineFor(s.Stmt.Pos()), 1, ignore, true)
}
p.stmt(s.Stmt, nextIsRBrace)
case *ast.ExprStmt:
const depth = 1
p.expr0(s.X, depth)
case *ast.SendStmt:
const depth = 1
p.expr0(s.Chan, depth)
p.print(blank, s.Arrow, token.ARROW, blank)
p.expr0(s.Value, depth)
case *ast.IncDecStmt:
const depth = 1
p.expr0(s.X, depth+1)
p.print(s.TokPos, s.Tok)
case *ast.AssignStmt:
var depth = 1
if len(s.Lhs) > 1 && len(s.Rhs) > 1 {
depth++
}
p.exprList(s.Pos(), s.Lhs, depth, 0, s.TokPos)
p.print(blank, s.TokPos, s.Tok, blank)
p.exprList(s.TokPos, s.Rhs, depth, 0, token.NoPos)
case *ast.GoStmt:
p.print(token.GO, blank)
p.expr(s.Call)
case *ast.DeferStmt:
p.print(token.DEFER, blank)
p.expr(s.Call)
case *ast.ReturnStmt:
p.print(token.RETURN)
if s.Results != nil {
p.print(blank)
p.exprList(s.Pos(), s.Results, 1, 0, token.NoPos)
}
case *ast.BranchStmt:
p.print(s.Tok)
if s.Label != nil {
p.print(blank)
p.expr(s.Label)
}
case *ast.BlockStmt:
p.block(s, 1)
case *ast.IfStmt:
p.print(token.IF)
p.controlClause(false, s.Init, s.Cond, nil)
p.block(s.Body, 1)
if s.Else != nil {
p.print(blank, token.ELSE, blank)
switch s.Else.(type) {
case *ast.BlockStmt, *ast.IfStmt:
p.stmt(s.Else, nextIsRBrace)
default:
p.print(token.LBRACE, indent, formfeed)
p.stmt(s.Else, true)
p.print(unindent, formfeed, token.RBRACE)
}
}
case *ast.CaseClause:
if s.List != nil {
p.print(token.CASE, blank)
p.exprList(s.Pos(), s.List, 1, 0, s.Colon)
} else {
p.print(token.DEFAULT)
}
p.print(s.Colon, token.COLON)
p.stmtList(s.Body, 1, nextIsRBrace)
case *ast.SwitchStmt:
p.print(token.SWITCH)
p.controlClause(false, s.Init, s.Tag, nil)
p.block(s.Body, 0)
case *ast.TypeSwitchStmt:
p.print(token.SWITCH)
if s.Init != nil {
p.print(blank)
p.stmt(s.Init, false)
p.print(token.SEMICOLON)
}
p.print(blank)
p.stmt(s.Assign, false)
p.print(blank)
p.block(s.Body, 0)
case *ast.CommClause:
if s.Comm != nil {
p.print(token.CASE, blank)
p.stmt(s.Comm, false)
} else {
p.print(token.DEFAULT)
}
p.print(s.Colon, token.COLON)
p.stmtList(s.Body, 1, nextIsRBrace)
case *ast.SelectStmt:
p.print(token.SELECT, blank)
body := s.Body
if len(body.List) == 0 && !p.commentBefore(p.posFor(body.Rbrace)) {
// print empty select statement w/o comments on one line
p.print(body.Lbrace, token.LBRACE, body.Rbrace, token.RBRACE)
} else {
p.block(body, 0)
}
case *ast.ForStmt:
p.print(token.FOR)
p.controlClause(true, s.Init, s.Cond, s.Post)
p.block(s.Body, 1)
case *ast.RangeStmt:
p.print(token.FOR, blank)
p.expr(s.Key)
if s.Value != nil {
// use position of value following the comma as
// comma position for correct comment placement
p.print(s.Value.Pos(), token.COMMA, blank)
p.expr(s.Value)
}
p.print(blank, s.TokPos, s.Tok, blank, token.RANGE, blank)
p.expr(stripParens(s.X))
p.print(blank)
p.block(s.Body, 1)
default:
panic("unreachable")
}
return
}
// checkStmt type checks a statement.
func (c *checker) checkStmt(s ast.Stmt) {
switch s := s.(type) {
case *ast.AssignStmt:
// TODO Each left-hand side operand must be addressable,
// a map index expression, or the blank identifier. Operands
// may be parenthesized.
if len(s.Rhs) == 1 {
idents := make([]*ast.Ident, len(s.Lhs))
for i, e := range s.Lhs {
if ident, ok := e.(*ast.Ident); ok {
if ident.Obj != nil {
idents[i] = ident
}
} else {
c.checkExpr(e, nil)
}
}
c.checkExpr(s.Rhs[0], idents)
} else {
idents := make([]*ast.Ident, 1)
for i, e := range s.Rhs {
if ident, ok := s.Lhs[i].(*ast.Ident); ok && ident.Obj != nil {
idents[0] = ident
c.checkExpr(e, idents)
} else {
c.checkExpr(e, nil)
}
}
}
case *ast.BlockStmt:
for _, s := range s.List {
c.checkStmt(s)
}
case *ast.ExprStmt:
c.checkExpr(s.X, nil)
case *ast.BranchStmt:
// no-op
case *ast.DeclStmt:
// Only a GenDecl/ValueSpec is permissible in a statement.
decl := s.Decl.(*ast.GenDecl)
for _, spec := range decl.Specs {
spec := spec.(*ast.ValueSpec)
for _, name := range spec.Names {
c.checkObj(name.Obj, true)
}
}
//case *ast.DeferStmt:
//case *ast.EmptyStmt:
case *ast.ForStmt:
if s.Init != nil {
c.checkStmt(s.Init)
}
// TODO make sure cond expr is some sort of bool.
if s.Cond != nil {
c.checkExpr(s.Cond, nil)
}
if s.Post != nil {
c.checkStmt(s.Post)
}
c.checkStmt(s.Body)
//case *ast.IncDecStmt:
//case *ast.GoStmt:
case *ast.IfStmt:
if s.Init != nil {
c.checkStmt(s.Init)
}
// TODO make sure cond expr is some sort of bool.
c.checkExpr(s.Cond, nil)
c.checkStmt(s.Body)
if s.Else != nil {
c.checkStmt(s.Else)
}
case *ast.IncDecStmt:
// TODO check operand is addressable.
// TODO check operand type is suitable for inc/dec.
c.checkExpr(s.X, nil)
case *ast.LabeledStmt:
c.checkStmt(s.Stmt)
case *ast.RangeStmt:
var k, v Type
switch x := Underlying(c.checkExpr(s.X, nil)).(type) {
case *Pointer:
if x, ok := Underlying(x.Base).(*Array); ok {
k, v = Int, x.Elt
} else {
c.errorf(s.Pos(), "invalid type for range")
return
}
case *Array:
k, v = Int, x.Elt
case *Slice:
k, v = Int, x.Elt
case *Map:
k, v = x.Key, x.Elt
case *Chan:
k = x.Elt
if s.Value != nil {
c.errorf(s.Pos(), "too many variables in range")
return
}
default:
c.errorf(s.Pos(), "invalid type for range")
return
}
// TODO check key, value are addressable and assignable from range
// values.
if ident, ok := s.Key.(*ast.Ident); ok && ident.Obj.Type == nil {
ident.Obj.Type = k
} else {
c.checkExpr(s.Key, nil)
}
if s.Value != nil {
if ident, ok := s.Value.(*ast.Ident); ok && ident.Obj.Type == nil {
ident.Obj.Type = v
} else {
c.checkExpr(s.Value, nil)
}
}
c.checkStmt(s.Body)
case *ast.ReturnStmt:
// TODO we need to check the result type(s) against the
// current function's declared return type(s). We need
// context for that.
for _, e := range s.Results {
c.checkExpr(e, nil)
}
//case *ast.SelectStmt:
//case *ast.SendStmt:
case *ast.SwitchStmt:
if s.Init != nil {
c.checkStmt(s.Init)
}
tag := Bool.Underlying // omitted tag == "true"
if s.Tag != nil {
tag = c.checkExpr(s.Tag, nil)
}
for _, s_ := range s.Body.List {
cc := s_.(*ast.CaseClause)
for _, e := range cc.List {
// TODO check type is comparable to tag.
t := c.checkExpr(e, nil)
_, _ = t, tag
}
for _, s := range cc.Body {
c.checkStmt(s)
}
}
//case *ast.TypeSwitchStmt:
default:
panic(fmt.Sprintf("unimplemented %T", s))
}
}
// stmt typechecks statement s.
func (check *checker) stmt(s ast.Stmt) {
switch s := s.(type) {
case *ast.BadStmt, *ast.EmptyStmt:
// ignore
case *ast.DeclStmt:
check.decl(s.Decl)
case *ast.LabeledStmt:
// TODO(gri) anything to do with label itself?
check.stmt(s.Stmt)
case *ast.ExprStmt:
var x operand
used := false
switch e := unparen(s.X).(type) {
case *ast.CallExpr:
// function calls are permitted
used = true
// but some builtins are excluded
check.expr(&x, e.Fun, nil, -1)
if x.mode != invalid {
if b, ok := x.typ.(*builtin); ok && !b.isStatement {
used = false
}
}
case *ast.UnaryExpr:
// receive operations are permitted
if e.Op == token.ARROW {
used = true
}
}
if !used {
check.errorf(s.Pos(), "%s not used", s.X)
// ok to continue
}
check.rawExpr(&x, s.X, nil, -1, false)
if x.mode == typexpr {
check.errorf(x.pos(), "%s is not an expression", &x)
}
case *ast.SendStmt:
var ch, x operand
check.expr(&ch, s.Chan, nil, -1)
check.expr(&x, s.Value, nil, -1)
if ch.mode == invalid || x.mode == invalid {
return
}
if tch, ok := underlying(ch.typ).(*Chan); !ok || tch.Dir&ast.SEND == 0 || !x.isAssignable(tch.Elt) {
check.invalidOp(ch.pos(), "cannot send %s to channel %s", &x, &ch)
}
case *ast.IncDecStmt:
var op token.Token
switch s.Tok {
case token.INC:
op = token.ADD
case token.DEC:
op = token.SUB
default:
check.invalidAST(s.TokPos, "unknown inc/dec operation %s", s.Tok)
return
}
var x, y operand
check.expr(&x, s.X, nil, -1)
check.expr(&y, &ast.BasicLit{ValuePos: x.pos(), Kind: token.INT, Value: "1"}, nil, -1) // use x's position
check.binary(&x, &y, op, nil)
check.assign1to1(s.X, nil, &x, false, -1)
case *ast.AssignStmt:
switch s.Tok {
case token.ASSIGN, token.DEFINE:
if len(s.Lhs) == 0 {
check.invalidAST(s.Pos(), "missing lhs in assignment")
return
}
check.assignNtoM(s.Lhs, s.Rhs, s.Tok == token.DEFINE, -1)
default:
// assignment operations
if len(s.Lhs) != 1 || len(s.Rhs) != 1 {
check.errorf(s.TokPos, "assignment operation %s requires single-valued expressions", s.Tok)
return
}
// TODO(gri) make this conversion more efficient
var op token.Token
switch s.Tok {
case token.ADD_ASSIGN:
op = token.ADD
case token.SUB_ASSIGN:
op = token.SUB
case token.MUL_ASSIGN:
op = token.MUL
case token.QUO_ASSIGN:
op = token.QUO
case token.REM_ASSIGN:
op = token.REM
case token.AND_ASSIGN:
op = token.AND
case token.OR_ASSIGN:
op = token.OR
case token.XOR_ASSIGN:
op = token.XOR
case token.SHL_ASSIGN:
op = token.SHL
case token.SHR_ASSIGN:
op = token.SHR
case token.AND_NOT_ASSIGN:
op = token.AND_NOT
default:
check.invalidAST(s.TokPos, "unknown assignment operation %s", s.Tok)
return
}
var x, y operand
check.expr(&x, s.Lhs[0], nil, -1)
check.expr(&y, s.Rhs[0], nil, -1)
check.binary(&x, &y, op, nil)
check.assign1to1(s.Lhs[0], nil, &x, false, -1)
}
case *ast.GoStmt:
check.call(s.Call)
case *ast.DeferStmt:
check.call(s.Call)
case *ast.ReturnStmt:
sig := check.functypes[len(check.functypes)-1]
if n := len(sig.Results); n > 0 {
// TODO(gri) should not have to compute lhs, named every single time - clean this up
lhs := make([]ast.Expr, n)
named := false // if set, function has named results
for i, res := range sig.Results {
if len(res.Name) > 0 {
// a blank (_) result parameter is a named result parameter!
named = true
}
name := ast.NewIdent(res.Name)
name.NamePos = s.Pos()
name.Obj = res
lhs[i] = name
}
if len(s.Results) > 0 || !named {
// TODO(gri) assignNtoM should perhaps not require len(lhs) > 0
check.assignNtoM(lhs, s.Results, false, -1)
}
} else if len(s.Results) > 0 {
check.errorf(s.Pos(), "no result values expected")
}
case *ast.BranchStmt:
unimplemented()
case *ast.BlockStmt:
check.stmtList(s.List)
case *ast.IfStmt:
check.optionalStmt(s.Init)
var x operand
check.expr(&x, s.Cond, nil, -1)
if !isBoolean(x.typ) {
check.errorf(s.Cond.Pos(), "non-boolean condition in if statement")
}
check.stmt(s.Body)
check.optionalStmt(s.Else)
case *ast.SwitchStmt:
check.optionalStmt(s.Init)
var x operand
if s.Tag != nil {
check.expr(&x, s.Tag, nil, -1)
} else {
// TODO(gri) should provide a position (see IncDec) for good error messages
x.mode = constant
x.typ = Typ[UntypedBool]
x.val = true
}
check.multipleDefaults(s.Body.List)
for _, s := range s.Body.List {
clause, _ := s.(*ast.CaseClause)
if clause == nil {
continue // error reported before
}
for _, expr := range clause.List {
var y operand
check.expr(&y, expr, nil, -1)
// TODO(gri) x and y must be comparable
}
check.stmtList(clause.Body)
}
case *ast.TypeSwitchStmt:
check.optionalStmt(s.Init)
// A type switch guard must be of the form:
//
// TypeSwitchGuard = [ identifier ":=" ] PrimaryExpr "." "(" "type" ")" .
//
// The parser is checking syntactic correctness;
// remaining syntactic errors are considered AST errors here.
// TODO(gri) better factoring of error handling (invalid ASTs)
//
var lhs *ast.Object // lhs identifier object or nil
var rhs ast.Expr
switch guard := s.Assign.(type) {
case *ast.ExprStmt:
rhs = guard.X
case *ast.AssignStmt:
if len(guard.Lhs) != 1 || guard.Tok != token.DEFINE || len(guard.Rhs) != 1 {
check.invalidAST(s.Pos(), "incorrect form of type switch guard")
return
}
ident, _ := guard.Lhs[0].(*ast.Ident)
if ident == nil {
check.invalidAST(s.Pos(), "incorrect form of type switch guard")
return
}
lhs = ident.Obj
rhs = guard.Rhs[0]
default:
check.invalidAST(s.Pos(), "incorrect form of type switch guard")
return
}
// rhs must be of the form: expr.(type) and expr must be an interface
expr, _ := rhs.(*ast.TypeAssertExpr)
if expr == nil || expr.Type != nil {
check.invalidAST(s.Pos(), "incorrect form of type switch guard")
return
}
var x operand
check.expr(&x, expr.X, nil, -1)
if x.mode == invalid {
return
}
var T *Interface
if T, _ = underlying(x.typ).(*Interface); T == nil {
check.errorf(x.pos(), "%s is not an interface", &x)
return
}
check.multipleDefaults(s.Body.List)
for _, s := range s.Body.List {
clause, _ := s.(*ast.CaseClause)
if clause == nil {
continue // error reported before
}
// Check each type in this type switch case.
var typ Type
for _, expr := range clause.List {
typ = check.typOrNil(expr, false)
if typ != nil && typ != Typ[Invalid] {
if method, wrongType := missingMethod(typ, T); method != nil {
var msg string
if wrongType {
msg = "%s cannot have dynamic type %s (wrong type for method %s)"
} else {
msg = "%s cannot have dynamic type %s (missing method %s)"
}
check.errorf(expr.Pos(), msg, &x, typ, method.Name)
// ok to continue
}
}
}
// If lhs exists, set its type for each clause.
if lhs != nil {
// In clauses with a case listing exactly one type, the variable has that type;
// otherwise, the variable has the type of the expression in the TypeSwitchGuard.
if len(clause.List) != 1 || typ == nil {
typ = x.typ
}
lhs.Type = typ
}
check.stmtList(clause.Body)
}
// There is only one object (lhs) associated with a lhs identifier, but that object
// assumes different types for different clauses. Set it to nil when we are done so
// that the type cannot be used by mistake.
if lhs != nil {
lhs.Type = nil
}
case *ast.SelectStmt:
check.multipleDefaults(s.Body.List)
for _, s := range s.Body.List {
clause, _ := s.(*ast.CommClause)
if clause == nil {
continue // error reported before
}
check.optionalStmt(clause.Comm) // TODO(gri) check correctness of c.Comm (must be Send/RecvStmt)
check.stmtList(clause.Body)
}
case *ast.ForStmt:
check.optionalStmt(s.Init)
if s.Cond != nil {
var x operand
check.expr(&x, s.Cond, nil, -1)
if !isBoolean(x.typ) {
check.errorf(s.Cond.Pos(), "non-boolean condition in for statement")
}
}
check.optionalStmt(s.Post)
check.stmt(s.Body)
case *ast.RangeStmt:
// check expression to iterate over
decl := s.Tok == token.DEFINE
var x operand
check.expr(&x, s.X, nil, -1)
if x.mode == invalid {
// if we don't have a declaration, we can still check the loop's body
if !decl {
check.stmt(s.Body)
}
return
}
// determine key/value types
var key, val Type
switch typ := underlying(x.typ).(type) {
case *Basic:
if isString(typ) {
key = Typ[UntypedInt]
val = Typ[UntypedRune]
}
case *Array:
key = Typ[UntypedInt]
val = typ.Elt
case *Slice:
key = Typ[UntypedInt]
val = typ.Elt
case *Pointer:
if typ, _ := underlying(typ.Base).(*Array); typ != nil {
key = Typ[UntypedInt]
val = typ.Elt
}
case *Map:
key = typ.Key
val = typ.Elt
case *Chan:
key = typ.Elt
if typ.Dir&ast.RECV == 0 {
check.errorf(x.pos(), "cannot range over send-only channel %s", &x)
// ok to continue
}
if s.Value != nil {
check.errorf(s.Value.Pos(), "iteration over %s permits only one iteration variable", &x)
// ok to continue
}
}
if key == nil {
check.errorf(x.pos(), "cannot range over %s", &x)
// if we don't have a declaration, we can still check the loop's body
if !decl {
check.stmt(s.Body)
}
return
}
// check assignment to/declaration of iteration variables
// TODO(gri) The error messages/positions are not great here,
// they refer to the expression in the range clause.
// Should give better messages w/o too much code
// duplication (assignment checking).
if s.Key != nil {
x.typ = key
check.assign1to1(s.Key, nil, &x, decl, -1)
} else {
check.invalidAST(s.Pos(), "range clause requires index iteration variable")
// ok to continue
}
if s.Value != nil {
x.typ = val
check.assign1to1(s.Value, nil, &x, decl, -1)
}
check.stmt(s.Body)
default:
check.errorf(s.Pos(), "invalid statement")
}
}
func (v *stmtVisitor) VisitStmt(s ast.Stmt) {
var statements *[]ast.Stmt
switch s := s.(type) {
case *ast.BlockStmt:
statements = &s.List
case *ast.CaseClause:
statements = &s.Body
case *ast.CommClause:
statements = &s.Body
case *ast.ForStmt:
if s.Init != nil {
v.VisitStmt(s.Init)
}
if s.Post != nil {
v.VisitStmt(s.Post)
}
v.VisitStmt(s.Body)
case *ast.IfStmt:
if s.Init != nil {
v.VisitStmt(s.Init)
}
v.VisitStmt(s.Body)
if s.Else != nil {
v.VisitStmt(s.Else)
}
case *ast.LabeledStmt:
v.VisitStmt(s.Stmt)
case *ast.RangeStmt:
v.VisitStmt(s.Body)
case *ast.SelectStmt:
v.VisitStmt(s.Body)
case *ast.SwitchStmt:
if s.Init != nil {
v.VisitStmt(s.Init)
}
v.VisitStmt(s.Body)
case *ast.TypeSwitchStmt:
if s.Init != nil {
v.VisitStmt(s.Init)
}
v.VisitStmt(s.Assign)
v.VisitStmt(s.Body)
}
if statements == nil {
return
}
for i := 0; i < len(*statements); i++ {
s := (*statements)[i]
switch s.(type) {
case *ast.CaseClause, *ast.CommClause, *ast.BlockStmt:
break
default:
start, end := v.fset.Position(s.Pos()), v.fset.Position(s.End())
stmtObj := v.functions[len(v.functions)-1].RegisterStatement(start.Offset, end.Offset)
expr := makeCall(fmt.Sprint(stmtObj, ".At"))
stmt := &ast.ExprStmt{X: expr}
item := []ast.Stmt{stmt}
*statements = append((*statements)[:i], append(item, (*statements)[i:]...)...)
i++
}
v.VisitStmt(s)
}
}
func (c *funcContext) translateStmt(stmt ast.Stmt, label string) {
c.Write([]byte{'\b'})
binary.Write(c, binary.BigEndian, uint32(stmt.Pos()))
switch s := stmt.(type) {
case *ast.BlockStmt:
c.translateStmtList(s.List)
case *ast.IfStmt:
c.printLabel(label)
if s.Init != nil {
c.translateStmt(s.Init, "")
}
var caseClauses []ast.Stmt
ifStmt := s
for {
caseClauses = append(caseClauses, &ast.CaseClause{List: []ast.Expr{ifStmt.Cond}, Body: ifStmt.Body.List})
switch elseStmt := ifStmt.Else.(type) {
case *ast.IfStmt:
if elseStmt.Init != nil {
caseClauses = append(caseClauses, &ast.CaseClause{List: nil, Body: []ast.Stmt{elseStmt}})
break
}
ifStmt = elseStmt
continue
case *ast.BlockStmt:
caseClauses = append(caseClauses, &ast.CaseClause{List: nil, Body: elseStmt.List})
case *ast.EmptyStmt, nil:
// no else clause
default:
panic(fmt.Sprintf("Unhandled else: %T\n", elseStmt))
}
break
}
c.translateBranchingStmt(caseClauses, false, c.translateExpr, nil, "", c.hasGoto[s])
case *ast.SwitchStmt:
if s.Init != nil {
c.translateStmt(s.Init, "")
}
translateCond := func(cond ast.Expr) *expression {
return c.translateExpr(cond)
}
if s.Tag != nil {
refVar := c.newVariable("_ref")
c.Printf("%s = %s;", refVar, c.translateExpr(s.Tag))
translateCond = func(cond ast.Expr) *expression {
refIdent := c.newIdent(refVar, c.p.info.Types[s.Tag].Type)
return c.translateExpr(&ast.BinaryExpr{
X: refIdent,
Op: token.EQL,
Y: cond,
})
}
}
c.translateBranchingStmt(s.Body.List, true, translateCond, nil, label, c.hasGoto[s])
case *ast.TypeSwitchStmt:
if s.Init != nil {
c.translateStmt(s.Init, "")
}
var expr ast.Expr
var typeSwitchVar string
switch a := s.Assign.(type) {
case *ast.AssignStmt:
expr = a.Rhs[0].(*ast.TypeAssertExpr).X
typeSwitchVar = c.newVariable(a.Lhs[0].(*ast.Ident).Name)
for _, caseClause := range s.Body.List {
c.p.objectVars[c.p.info.Implicits[caseClause]] = typeSwitchVar
}
case *ast.ExprStmt:
expr = a.X.(*ast.TypeAssertExpr).X
}
refVar := c.newVariable("_ref")
typeVar := c.newVariable("_type")
c.Printf("%s = %s;", refVar, c.translateExpr(expr))
c.Printf("%s = %s !== null ? %s.constructor : null;", typeVar, refVar, refVar)
translateCond := func(cond ast.Expr) *expression {
return c.formatExpr("%s", c.typeCheck(typeVar, c.p.info.Types[cond].Type))
}
printCaseBodyPrefix := func(conds []ast.Expr) {
if typeSwitchVar == "" {
return
}
value := refVar
if len(conds) == 1 {
t := c.p.info.Types[conds[0]].Type
if _, isInterface := t.Underlying().(*types.Interface); !isInterface && !types.Identical(t, types.Typ[types.UntypedNil]) {
value += ".go$val"
}
}
c.Printf("%s = %s;", typeSwitchVar, value)
}
c.translateBranchingStmt(s.Body.List, true, translateCond, printCaseBodyPrefix, label, c.hasGoto[s])
case *ast.ForStmt:
if s.Init != nil {
c.translateStmt(s.Init, "")
}
cond := "true"
if s.Cond != nil {
cond = c.translateExpr(s.Cond).String()
}
c.translateLoopingStmt(cond, s.Body, nil, func() {
if s.Post != nil {
c.translateStmt(s.Post, "")
}
}, label, c.hasGoto[s])
case *ast.RangeStmt:
refVar := c.newVariable("_ref")
c.Printf("%s = %s;", refVar, c.translateExpr(s.X))
iVar := c.newVariable("_i")
c.Printf("%s = 0;", iVar)
switch t := c.p.info.Types[s.X].Type.Underlying().(type) {
case *types.Basic:
runeVar := c.newVariable("_rune")
c.translateLoopingStmt(iVar+" < "+refVar+".length", s.Body, func() {
c.Printf("%s = go$decodeRune(%s, %s);", runeVar, refVar, iVar)
if !isBlank(s.Value) {
c.Printf("%s", c.translateAssign(s.Value, runeVar+"[0]"))
}
if !isBlank(s.Key) {
c.Printf("%s", c.translateAssign(s.Key, iVar))
}
}, func() {
c.Printf("%s += %s[1];", iVar, runeVar)
}, label, c.hasGoto[s])
case *types.Map:
keysVar := c.newVariable("_keys")
c.Printf("%s = go$keys(%s);", keysVar, refVar)
c.translateLoopingStmt(iVar+" < "+keysVar+".length", s.Body, func() {
entryVar := c.newVariable("_entry")
c.Printf("%s = %s[%s[%s]];", entryVar, refVar, keysVar, iVar)
if !isBlank(s.Value) {
c.Printf("%s", c.translateAssign(s.Value, entryVar+".v"))
}
if !isBlank(s.Key) {
c.Printf("%s", c.translateAssign(s.Key, entryVar+".k"))
}
}, func() {
c.Printf("%s++;", iVar)
}, label, c.hasGoto[s])
case *types.Array, *types.Pointer, *types.Slice:
var length string
switch t2 := t.(type) {
case *types.Array:
length = fmt.Sprintf("%d", t2.Len())
case *types.Pointer:
length = fmt.Sprintf("%d", t2.Elem().Underlying().(*types.Array).Len())
case *types.Slice:
length = refVar + ".length"
}
c.translateLoopingStmt(iVar+" < "+length, s.Body, func() {
if !isBlank(s.Value) {
indexExpr := &ast.IndexExpr{
X: c.newIdent(refVar, t),
Index: c.newIdent(iVar, types.Typ[types.Int]),
}
et := elemType(t)
c.p.info.Types[indexExpr] = types.TypeAndValue{Type: et}
c.Printf("%s", c.translateAssign(s.Value, c.translateImplicitConversion(indexExpr, et).String()))
}
if !isBlank(s.Key) {
c.Printf("%s", c.translateAssign(s.Key, iVar))
}
}, func() {
c.Printf("%s++;", iVar)
}, label, c.hasGoto[s])
case *types.Chan:
c.printLabel(label)
// skip
default:
panic("")
}
case *ast.BranchStmt:
c.printLabel(label)
labelSuffix := ""
data := c.flowDatas[""]
if s.Label != nil {
labelSuffix = " " + s.Label.Name
data = c.flowDatas[s.Label.Name]
}
switch s.Tok {
case token.BREAK:
c.PrintCond(data.endCase == 0, fmt.Sprintf("break%s;", labelSuffix), fmt.Sprintf("go$s = %d; continue;", data.endCase))
case token.CONTINUE:
data.postStmt()
c.PrintCond(data.beginCase == 0, fmt.Sprintf("continue%s;", labelSuffix), fmt.Sprintf("go$s = %d; continue;", data.beginCase))
case token.GOTO:
c.PrintCond(false, "goto "+s.Label.Name, fmt.Sprintf("go$s = %d; continue;", c.labelCases[s.Label.Name]))
case token.FALLTHROUGH:
// handled in CaseClause
default:
panic("Unhandled branch statment: " + s.Tok.String())
}
case *ast.ReturnStmt:
c.printLabel(label)
results := s.Results
if c.resultNames != nil {
if len(s.Results) != 0 {
c.translateStmt(&ast.AssignStmt{
Lhs: c.resultNames,
Tok: token.ASSIGN,
Rhs: s.Results,
}, "")
}
results = c.resultNames
}
switch len(results) {
case 0:
c.Printf("return;")
case 1:
if c.sig.Results().Len() > 1 {
c.Printf("return %s;", c.translateExpr(results[0]))
break
}
v := c.translateImplicitConversion(results[0], c.sig.Results().At(0).Type())
c.delayedOutput = nil
c.Printf("return %s;", v)
default:
values := make([]string, len(results))
for i, result := range results {
values[i] = c.translateImplicitConversion(result, c.sig.Results().At(i).Type()).String()
}
c.delayedOutput = nil
c.Printf("return [%s];", strings.Join(values, ", "))
}
case *ast.DeferStmt:
c.printLabel(label)
if ident, isIdent := s.Call.Fun.(*ast.Ident); isIdent {
if builtin, isBuiltin := c.p.info.Uses[ident].(*types.Builtin); isBuiltin {
if builtin.Name() == "recover" {
c.Printf("go$deferred.push({ fun: go$recover, args: [] });")
return
}
args := make([]ast.Expr, len(s.Call.Args))
for i, arg := range s.Call.Args {
args[i] = c.newIdent(c.newVariable("_arg"), c.p.info.Types[arg].Type)
}
call := c.translateExpr(&ast.CallExpr{
Fun: s.Call.Fun,
Args: args,
Ellipsis: s.Call.Ellipsis,
})
c.Printf("go$deferred.push({ fun: function(%s) { %s; }, args: [%s] });", strings.Join(c.translateExprSlice(args, nil), ", "), call, strings.Join(c.translateExprSlice(s.Call.Args, nil), ", "))
return
}
}
sig := c.p.info.Types[s.Call.Fun].Type.Underlying().(*types.Signature)
args := strings.Join(c.translateArgs(sig, s.Call.Args, s.Call.Ellipsis.IsValid()), ", ")
if sel, isSelector := s.Call.Fun.(*ast.SelectorExpr); isSelector {
obj := c.p.info.Selections[sel].Obj()
if !obj.Exported() {
c.p.dependencies[obj] = true
}
c.Printf(`go$deferred.push({ recv: %s, method: "%s", args: [%s] });`, c.translateExpr(sel.X), sel.Sel.Name, args)
return
}
c.Printf("go$deferred.push({ fun: %s, args: [%s] });", c.translateExpr(s.Call.Fun), args)
case *ast.AssignStmt:
c.printLabel(label)
if s.Tok != token.ASSIGN && s.Tok != token.DEFINE {
var op token.Token
switch s.Tok {
case token.ADD_ASSIGN:
op = token.ADD
case token.SUB_ASSIGN:
op = token.SUB
case token.MUL_ASSIGN:
op = token.MUL
case token.QUO_ASSIGN:
op = token.QUO
case token.REM_ASSIGN:
op = token.REM
case token.AND_ASSIGN:
op = token.AND
case token.OR_ASSIGN:
op = token.OR
case token.XOR_ASSIGN:
op = token.XOR
case token.SHL_ASSIGN:
op = token.SHL
case token.SHR_ASSIGN:
op = token.SHR
case token.AND_NOT_ASSIGN:
op = token.AND_NOT
default:
panic(s.Tok)
}
var parts []string
lhs := s.Lhs[0]
switch l := lhs.(type) {
case *ast.IndexExpr:
lhsVar := c.newVariable("_lhs")
indexVar := c.newVariable("_index")
parts = append(parts, lhsVar+" = "+c.translateExpr(l.X).String()+";")
parts = append(parts, indexVar+" = "+c.translateExpr(l.Index).String()+";")
lhs = &ast.IndexExpr{
X: c.newIdent(lhsVar, c.p.info.Types[l.X].Type),
Index: c.newIdent(indexVar, c.p.info.Types[l.Index].Type),
}
c.p.info.Types[lhs] = c.p.info.Types[l]
case *ast.StarExpr:
lhsVar := c.newVariable("_lhs")
parts = append(parts, lhsVar+" = "+c.translateExpr(l.X).String()+";")
lhs = &ast.StarExpr{
X: c.newIdent(lhsVar, c.p.info.Types[l.X].Type),
}
c.p.info.Types[lhs] = c.p.info.Types[l]
case *ast.SelectorExpr:
v := hasCallVisitor{c.p.info, false}
ast.Walk(&v, l.X)
if v.hasCall {
lhsVar := c.newVariable("_lhs")
parts = append(parts, lhsVar+" = "+c.translateExpr(l.X).String()+";")
lhs = &ast.SelectorExpr{
X: c.newIdent(lhsVar, c.p.info.Types[l.X].Type),
Sel: l.Sel,
}
c.p.info.Types[lhs] = c.p.info.Types[l]
c.p.info.Selections[lhs.(*ast.SelectorExpr)] = c.p.info.Selections[l]
}
}
parenExpr := &ast.ParenExpr{X: s.Rhs[0]}
c.p.info.Types[parenExpr] = c.p.info.Types[s.Rhs[0]]
binaryExpr := &ast.BinaryExpr{
X: lhs,
Op: op,
Y: parenExpr,
}
c.p.info.Types[binaryExpr] = c.p.info.Types[s.Lhs[0]]
parts = append(parts, c.translateAssign(lhs, c.translateExpr(binaryExpr).String()))
c.Printf("%s", strings.Join(parts, " "))
return
}
if s.Tok == token.DEFINE {
for _, lhs := range s.Lhs {
if !isBlank(lhs) {
c.p.info.Types[lhs] = types.TypeAndValue{Type: c.p.info.Defs[lhs.(*ast.Ident)].Type()}
}
}
}
removeParens := func(e ast.Expr) ast.Expr {
for {
if p, isParen := e.(*ast.ParenExpr); isParen {
e = p.X
continue
}
break
}
return e
}
switch {
case len(s.Lhs) == 1 && len(s.Rhs) == 1:
lhs := removeParens(s.Lhs[0])
if isBlank(lhs) {
v := hasCallVisitor{c.p.info, false}
ast.Walk(&v, s.Rhs[0])
if v.hasCall {
c.Printf("%s;", c.translateExpr(s.Rhs[0]).String())
}
return
}
c.Printf("%s", c.translateAssign(lhs, c.translateImplicitConversion(s.Rhs[0], c.p.info.Types[s.Lhs[0]].Type).String()))
case len(s.Lhs) > 1 && len(s.Rhs) == 1:
tupleVar := c.newVariable("_tuple")
out := tupleVar + " = " + c.translateExpr(s.Rhs[0]).String() + ";"
tuple := c.p.info.Types[s.Rhs[0]].Type.(*types.Tuple)
for i, lhs := range s.Lhs {
lhs = removeParens(lhs)
if !isBlank(lhs) {
out += " " + c.translateAssign(lhs, c.translateImplicitConversion(c.newIdent(fmt.Sprintf("%s[%d]", tupleVar, i), tuple.At(i).Type()), c.p.info.Types[s.Lhs[i]].Type).String())
}
}
c.Printf("%s", out)
case len(s.Lhs) == len(s.Rhs):
parts := make([]string, len(s.Rhs))
for i, rhs := range s.Rhs {
parts[i] = c.translateImplicitConversion(rhs, c.p.info.Types[s.Lhs[i]].Type).String()
}
tupleVar := c.newVariable("_tuple")
out := tupleVar + " = [" + strings.Join(parts, ", ") + "];"
for i, lhs := range s.Lhs {
lhs = removeParens(lhs)
if !isBlank(lhs) {
out += " " + c.translateAssign(lhs, fmt.Sprintf("%s[%d]", tupleVar, i))
}
}
c.Printf("%s", out)
default:
panic("Invalid arity of AssignStmt.")
}
case *ast.IncDecStmt:
t := c.p.info.Types[s.X].Type
if iExpr, isIExpr := s.X.(*ast.IndexExpr); isIExpr {
switch u := c.p.info.Types[iExpr.X].Type.Underlying().(type) {
case *types.Array:
t = u.Elem()
case *types.Slice:
t = u.Elem()
case *types.Map:
t = u.Elem()
}
}
tok := token.ADD_ASSIGN
if s.Tok == token.DEC {
tok = token.SUB_ASSIGN
}
one := &ast.BasicLit{
Kind: token.INT,
Value: "1",
}
c.p.info.Types[one] = types.TypeAndValue{Type: t, Value: exact.MakeInt64(1)}
c.translateStmt(&ast.AssignStmt{
Lhs: []ast.Expr{s.X},
Tok: tok,
Rhs: []ast.Expr{one},
}, label)
case *ast.ExprStmt:
c.printLabel(label)
c.Printf("%s;", c.translateExpr(s.X).String())
case *ast.DeclStmt:
c.printLabel(label)
decl := s.Decl.(*ast.GenDecl)
switch decl.Tok {
case token.VAR:
for _, spec := range s.Decl.(*ast.GenDecl).Specs {
valueSpec := spec.(*ast.ValueSpec)
lhs := make([]ast.Expr, len(valueSpec.Names))
for i, name := range valueSpec.Names {
lhs[i] = name
}
rhs := valueSpec.Values
isTuple := false
if len(rhs) == 1 {
_, isTuple = c.p.info.Types[rhs[0]].Type.(*types.Tuple)
}
for len(rhs) < len(lhs) && !isTuple {
rhs = append(rhs, nil)
}
c.translateStmt(&ast.AssignStmt{
Lhs: lhs,
Tok: token.DEFINE,
Rhs: rhs,
}, "")
}
case token.TYPE:
for _, spec := range decl.Specs {
o := c.p.info.Defs[spec.(*ast.TypeSpec).Name].(*types.TypeName)
c.translateType(o, false)
c.initType(o)
}
case token.CONST:
// skip, constants are inlined
}
case *ast.LabeledStmt:
c.printLabel(label)
c.translateStmt(s.Stmt, s.Label.Name)
case *ast.SelectStmt:
c.printLabel(label)
c.Printf(`go$notSupported("select");`)
case *ast.GoStmt:
c.printLabel(label)
c.Printf(`go$notSupported("go");`)
case *ast.SendStmt:
c.printLabel(label)
c.Printf(`go$notSupported("send");`)
case *ast.EmptyStmt:
// skip
default:
panic(fmt.Sprintf("Unhandled statement: %T\n", s))
}
}
func (a *blockCompiler) compileStmt(s ast.Stmt) {
sc := &stmtCompiler{a, s.Pos(), nil}
sc.compile(s)
}
// stmt typechecks statement s.
func (check *checker) stmt(s ast.Stmt) {
switch s := s.(type) {
case *ast.BadStmt, *ast.EmptyStmt:
// ignore
case *ast.DeclStmt:
d, _ := s.Decl.(*ast.GenDecl)
if d == nil || (d.Tok != token.CONST && d.Tok != token.TYPE && d.Tok != token.VAR) {
check.invalidAST(token.NoPos, "const, type, or var declaration expected")
return
}
if d.Tok == token.CONST {
check.assocInitvals(d)
}
check.decl(d)
case *ast.LabeledStmt:
// TODO(gri) anything to do with label itself?
check.stmt(s.Stmt)
case *ast.ExprStmt:
var x operand
used := false
switch e := unparen(s.X).(type) {
case *ast.CallExpr:
// function calls are permitted
used = true
// but some builtins are excluded
// (Caution: This evaluates e.Fun twice, once here and once
// below as part of s.X. This has consequences for
// check.register. Perhaps this can be avoided.)
check.expr(&x, e.Fun, nil, -1)
if x.mode != invalid {
if b, ok := x.typ.(*builtin); ok && !b.isStatement {
used = false
}
}
case *ast.UnaryExpr:
// receive operations are permitted
if e.Op == token.ARROW {
used = true
}
}
if !used {
check.errorf(s.Pos(), "%s not used", s.X)
// ok to continue
}
check.rawExpr(&x, s.X, nil, -1, false)
if x.mode == typexpr {
check.errorf(x.pos(), "%s is not an expression", &x)
}
case *ast.SendStmt:
var ch, x operand
check.expr(&ch, s.Chan, nil, -1)
check.expr(&x, s.Value, nil, -1)
if ch.mode == invalid || x.mode == invalid {
return
}
if tch, ok := underlying(ch.typ).(*Chan); !ok || tch.Dir&ast.SEND == 0 || !check.assignment(&x, tch.Elt) {
if x.mode != invalid {
check.invalidOp(ch.pos(), "cannot send %s to channel %s", &x, &ch)
}
}
case *ast.IncDecStmt:
var op token.Token
switch s.Tok {
case token.INC:
op = token.ADD
case token.DEC:
op = token.SUB
default:
check.invalidAST(s.TokPos, "unknown inc/dec operation %s", s.Tok)
return
}
var x operand
Y := &ast.BasicLit{ValuePos: s.X.Pos(), Kind: token.INT, Value: "1"} // use x's position
check.binary(&x, s.X, Y, op, -1)
if x.mode == invalid {
return
}
check.assign1to1(s.X, nil, &x, false, -1)
case *ast.AssignStmt:
switch s.Tok {
case token.ASSIGN, token.DEFINE:
if len(s.Lhs) == 0 {
check.invalidAST(s.Pos(), "missing lhs in assignment")
return
}
check.assignNtoM(s.Lhs, s.Rhs, s.Tok == token.DEFINE, -1)
default:
// assignment operations
if len(s.Lhs) != 1 || len(s.Rhs) != 1 {
check.errorf(s.TokPos, "assignment operation %s requires single-valued expressions", s.Tok)
return
}
// TODO(gri) make this conversion more efficient
var op token.Token
switch s.Tok {
case token.ADD_ASSIGN:
op = token.ADD
case token.SUB_ASSIGN:
op = token.SUB
case token.MUL_ASSIGN:
op = token.MUL
case token.QUO_ASSIGN:
op = token.QUO
case token.REM_ASSIGN:
op = token.REM
case token.AND_ASSIGN:
op = token.AND
case token.OR_ASSIGN:
op = token.OR
case token.XOR_ASSIGN:
op = token.XOR
case token.SHL_ASSIGN:
op = token.SHL
case token.SHR_ASSIGN:
op = token.SHR
case token.AND_NOT_ASSIGN:
op = token.AND_NOT
default:
check.invalidAST(s.TokPos, "unknown assignment operation %s", s.Tok)
return
}
var x operand
check.binary(&x, s.Lhs[0], s.Rhs[0], op, -1)
if x.mode == invalid {
return
}
check.assign1to1(s.Lhs[0], nil, &x, false, -1)
}
case *ast.GoStmt:
check.call(s.Call)
case *ast.DeferStmt:
check.call(s.Call)
case *ast.ReturnStmt:
sig := check.funcsig
if n := len(sig.Results); n > 0 {
// TODO(gri) should not have to compute lhs, named every single time - clean this up
lhs := make([]ast.Expr, n)
named := false // if set, function has named results
for i, res := range sig.Results {
if len(res.Name) > 0 {
// a blank (_) result parameter is a named result
named = true
}
name := ast.NewIdent(res.Name)
name.NamePos = s.Pos()
check.register(name, &Var{Name: res.Name, Type: res.Type}) // Pkg == nil
lhs[i] = name
}
if len(s.Results) > 0 || !named {
// TODO(gri) assignNtoM should perhaps not require len(lhs) > 0
check.assignNtoM(lhs, s.Results, false, -1)
}
} else if len(s.Results) > 0 {
check.errorf(s.Pos(), "no result values expected")
}
case *ast.BranchStmt:
// TODO(gri) implement this
case *ast.BlockStmt:
check.stmtList(s.List)
case *ast.IfStmt:
check.optionalStmt(s.Init)
var x operand
check.expr(&x, s.Cond, nil, -1)
if x.mode != invalid && !isBoolean(x.typ) {
check.errorf(s.Cond.Pos(), "non-boolean condition in if statement")
}
check.stmt(s.Body)
check.optionalStmt(s.Else)
case *ast.SwitchStmt:
check.optionalStmt(s.Init)
var x operand
tag := s.Tag
if tag == nil {
// use fake true tag value and position it at the opening { of the switch
ident := &ast.Ident{NamePos: s.Body.Lbrace, Name: "true"}
check.register(ident, Universe.Lookup("true"))
tag = ident
}
check.expr(&x, tag, nil, -1)
check.multipleDefaults(s.Body.List)
// TODO(gri) check also correct use of fallthrough
seen := make(map[interface{}]token.Pos)
for _, s := range s.Body.List {
clause, _ := s.(*ast.CaseClause)
if clause == nil {
continue // error reported before
}
if x.mode != invalid {
for _, expr := range clause.List {
x := x // copy of x (don't modify original)
var y operand
check.expr(&y, expr, nil, -1)
if y.mode == invalid {
continue // error reported before
}
// If we have a constant case value, it must appear only
// once in the switch statement. Determine if there is a
// duplicate entry, but only report an error if there are
// no other errors.
var dupl token.Pos
var yy operand
if y.mode == constant {
// TODO(gri) This code doesn't work correctly for
// large integer, floating point, or
// complex values - the respective struct
// comparisons are shallow. Need to use a
// hash function to index the map.
dupl = seen[y.val]
seen[y.val] = y.pos()
yy = y // remember y
}
// TODO(gri) The convertUntyped call pair below appears in other places. Factor!
// Order matters: By comparing y against x, error positions are at the case values.
check.convertUntyped(&y, x.typ)
if y.mode == invalid {
continue // error reported before
}
check.convertUntyped(&x, y.typ)
if x.mode == invalid {
continue // error reported before
}
check.comparison(&y, &x, token.EQL)
if y.mode != invalid && dupl.IsValid() {
check.errorf(yy.pos(), "%s is duplicate case (previous at %s)",
&yy, check.fset.Position(dupl))
}
}
}
check.stmtList(clause.Body)
}
case *ast.TypeSwitchStmt:
check.optionalStmt(s.Init)
// A type switch guard must be of the form:
//
// TypeSwitchGuard = [ identifier ":=" ] PrimaryExpr "." "(" "type" ")" .
//
// The parser is checking syntactic correctness;
// remaining syntactic errors are considered AST errors here.
// TODO(gri) better factoring of error handling (invalid ASTs)
//
var lhs *Var // lhs variable or nil
var rhs ast.Expr
switch guard := s.Assign.(type) {
case *ast.ExprStmt:
rhs = guard.X
case *ast.AssignStmt:
if len(guard.Lhs) != 1 || guard.Tok != token.DEFINE || len(guard.Rhs) != 1 {
check.invalidAST(s.Pos(), "incorrect form of type switch guard")
return
}
ident, _ := guard.Lhs[0].(*ast.Ident)
if ident == nil {
check.invalidAST(s.Pos(), "incorrect form of type switch guard")
return
}
lhs = check.lookup(ident).(*Var)
rhs = guard.Rhs[0]
default:
check.invalidAST(s.Pos(), "incorrect form of type switch guard")
return
}
// rhs must be of the form: expr.(type) and expr must be an interface
expr, _ := rhs.(*ast.TypeAssertExpr)
if expr == nil || expr.Type != nil {
check.invalidAST(s.Pos(), "incorrect form of type switch guard")
return
}
var x operand
check.expr(&x, expr.X, nil, -1)
if x.mode == invalid {
return
}
var T *Interface
if T, _ = underlying(x.typ).(*Interface); T == nil {
check.errorf(x.pos(), "%s is not an interface", &x)
return
}
check.multipleDefaults(s.Body.List)
for _, s := range s.Body.List {
clause, _ := s.(*ast.CaseClause)
if clause == nil {
continue // error reported before
}
// Check each type in this type switch case.
var typ Type
for _, expr := range clause.List {
typ = check.typOrNil(expr, false)
if typ != nil && typ != Typ[Invalid] {
if method, wrongType := missingMethod(typ, T); method != nil {
var msg string
if wrongType {
msg = "%s cannot have dynamic type %s (wrong type for method %s)"
} else {
msg = "%s cannot have dynamic type %s (missing method %s)"
}
check.errorf(expr.Pos(), msg, &x, typ, method.Name)
// ok to continue
}
}
}
// If lhs exists, set its type for each clause.
if lhs != nil {
// In clauses with a case listing exactly one type, the variable has that type;
// otherwise, the variable has the type of the expression in the TypeSwitchGuard.
if len(clause.List) != 1 || typ == nil {
typ = x.typ
}
lhs.Type = typ
}
check.stmtList(clause.Body)
}
// There is only one object (lhs) associated with a lhs identifier, but that object
// assumes different types for different clauses. Set it back to the type of the
// TypeSwitchGuard expression so that that variable always has a valid type.
if lhs != nil {
lhs.Type = x.typ
}
case *ast.SelectStmt:
check.multipleDefaults(s.Body.List)
for _, s := range s.Body.List {
clause, _ := s.(*ast.CommClause)
if clause == nil {
continue // error reported before
}
check.optionalStmt(clause.Comm) // TODO(gri) check correctness of c.Comm (must be Send/RecvStmt)
check.stmtList(clause.Body)
}
case *ast.ForStmt:
check.optionalStmt(s.Init)
if s.Cond != nil {
var x operand
check.expr(&x, s.Cond, nil, -1)
if x.mode != invalid && !isBoolean(x.typ) {
check.errorf(s.Cond.Pos(), "non-boolean condition in for statement")
}
}
check.optionalStmt(s.Post)
check.stmt(s.Body)
case *ast.RangeStmt:
// check expression to iterate over
decl := s.Tok == token.DEFINE
var x operand
check.expr(&x, s.X, nil, -1)
if x.mode == invalid {
// if we don't have a declaration, we can still check the loop's body
if !decl {
check.stmt(s.Body)
}
return
}
// determine key/value types
var key, val Type
switch typ := underlying(x.typ).(type) {
case *Basic:
if isString(typ) {
key = Typ[UntypedInt]
val = Typ[UntypedRune]
}
case *Array:
key = Typ[UntypedInt]
val = typ.Elt
case *Slice:
key = Typ[UntypedInt]
val = typ.Elt
case *Pointer:
if typ, _ := underlying(typ.Base).(*Array); typ != nil {
key = Typ[UntypedInt]
val = typ.Elt
}
case *Map:
key = typ.Key
val = typ.Elt
case *Chan:
key = typ.Elt
if typ.Dir&ast.RECV == 0 {
check.errorf(x.pos(), "cannot range over send-only channel %s", &x)
// ok to continue
}
if s.Value != nil {
check.errorf(s.Value.Pos(), "iteration over %s permits only one iteration variable", &x)
// ok to continue
}
}
if key == nil {
check.errorf(x.pos(), "cannot range over %s", &x)
// if we don't have a declaration, we can still check the loop's body
if !decl {
check.stmt(s.Body)
}
return
}
// check assignment to/declaration of iteration variables
// TODO(gri) The error messages/positions are not great here,
// they refer to the expression in the range clause.
// Should give better messages w/o too much code
// duplication (assignment checking).
x.mode = value
if s.Key != nil {
x.typ = key
x.expr = s.Key
check.assign1to1(s.Key, nil, &x, decl, -1)
} else {
check.invalidAST(s.Pos(), "range clause requires index iteration variable")
// ok to continue
}
if s.Value != nil {
x.typ = val
x.expr = s.Value
check.assign1to1(s.Value, nil, &x, decl, -1)
}
check.stmt(s.Body)
default:
check.errorf(s.Pos(), "invalid statement")
}
}
// stmt typechecks statement s.
func (check *checker) stmt(ctxt stmtContext, s ast.Stmt) {
// statements cannot use iota in general
// (constant declarations set it explicitly)
assert(check.iota == nil)
// statements must end with the same top scope as they started with
if debug {
defer func(scope *Scope) {
// don't check if code is panicking
if p := recover(); p != nil {
panic(p)
}
assert(scope == check.topScope)
}(check.topScope)
}
inner := ctxt &^ fallthroughOk
switch s := s.(type) {
case *ast.BadStmt, *ast.EmptyStmt:
// ignore
case *ast.DeclStmt:
check.declStmt(s.Decl)
case *ast.LabeledStmt:
check.hasLabel = true
check.stmt(ctxt, s.Stmt)
case *ast.ExprStmt:
// spec: "With the exception of specific built-in functions,
// function and method calls and receive operations can appear
// in statement context. Such statements may be parenthesized."
var x operand
kind := check.rawExpr(&x, s.X, nil)
var msg string
switch x.mode {
default:
if kind == statement {
return
}
msg = "is not used"
case builtin:
msg = "must be called"
case typexpr:
msg = "is not an expression"
}
check.errorf(x.pos(), "%s %s", &x, msg)
case *ast.SendStmt:
var ch, x operand
check.expr(&ch, s.Chan)
check.expr(&x, s.Value)
if ch.mode == invalid || x.mode == invalid {
return
}
if tch, ok := ch.typ.Underlying().(*Chan); !ok || tch.dir&ast.SEND == 0 || !check.assignment(&x, tch.elem) {
if x.mode != invalid {
check.invalidOp(ch.pos(), "cannot send %s to channel %s", &x, &ch)
}
}
case *ast.IncDecStmt:
var op token.Token
switch s.Tok {
case token.INC:
op = token.ADD
case token.DEC:
op = token.SUB
default:
check.invalidAST(s.TokPos, "unknown inc/dec operation %s", s.Tok)
return
}
var x operand
Y := &ast.BasicLit{ValuePos: s.X.Pos(), Kind: token.INT, Value: "1"} // use x's position
check.binary(&x, s.X, Y, op)
if x.mode == invalid {
return
}
check.assignVar(s.X, &x)
case *ast.AssignStmt:
switch s.Tok {
case token.ASSIGN, token.DEFINE:
if len(s.Lhs) == 0 {
check.invalidAST(s.Pos(), "missing lhs in assignment")
return
}
if s.Tok == token.DEFINE {
check.shortVarDecl(s.TokPos, s.Lhs, s.Rhs)
} else {
// regular assignment
check.assignVars(s.Lhs, s.Rhs)
}
default:
// assignment operations
if len(s.Lhs) != 1 || len(s.Rhs) != 1 {
check.errorf(s.TokPos, "assignment operation %s requires single-valued expressions", s.Tok)
return
}
op := assignOp(s.Tok)
if op == token.ILLEGAL {
check.invalidAST(s.TokPos, "unknown assignment operation %s", s.Tok)
return
}
var x operand
check.binary(&x, s.Lhs[0], s.Rhs[0], op)
if x.mode == invalid {
return
}
check.assignVar(s.Lhs[0], &x)
}
case *ast.GoStmt:
check.suspendedCall("go", s.Call)
case *ast.DeferStmt:
check.suspendedCall("defer", s.Call)
case *ast.ReturnStmt:
sig := check.funcSig
if n := sig.results.Len(); n > 0 {
// determine if the function has named results
named := false
lhs := make([]*Var, n)
for i, res := range sig.results.vars {
if res.name != "" {
// a blank (_) result parameter is a named result
named = true
}
lhs[i] = res
}
if len(s.Results) > 0 || !named {
check.initVars(lhs, s.Results, s.Return)
return
}
} else if len(s.Results) > 0 {
check.errorf(s.Pos(), "no result values expected")
}
case *ast.BranchStmt:
if s.Label != nil {
check.hasLabel = true
return // checked in 2nd pass (check.labels)
}
switch s.Tok {
case token.BREAK:
if ctxt&inBreakable == 0 {
check.errorf(s.Pos(), "break not in for, switch, or select statement")
}
case token.CONTINUE:
if ctxt&inContinuable == 0 {
check.errorf(s.Pos(), "continue not in for statement")
}
case token.FALLTHROUGH:
if ctxt&fallthroughOk == 0 {
check.errorf(s.Pos(), "fallthrough statement out of place")
}
default:
check.invalidAST(s.Pos(), "branch statement: %s", s.Tok)
}
case *ast.BlockStmt:
check.openScope(s)
defer check.closeScope()
check.stmtList(inner, s.List)
case *ast.IfStmt:
check.openScope(s)
defer check.closeScope()
check.initStmt(s.Init)
var x operand
check.expr(&x, s.Cond)
if x.mode != invalid && !isBoolean(x.typ) {
check.errorf(s.Cond.Pos(), "non-boolean condition in if statement")
}
check.stmt(inner, s.Body)
if s.Else != nil {
check.stmt(inner, s.Else)
}
case *ast.SwitchStmt:
inner |= inBreakable
check.openScope(s)
defer check.closeScope()
check.initStmt(s.Init)
var x operand
tag := s.Tag
if tag == nil {
// use fake true tag value and position it at the opening { of the switch
ident := &ast.Ident{NamePos: s.Body.Lbrace, Name: "true"}
check.recordObject(ident, Universe.Lookup("true"))
tag = ident
}
check.expr(&x, tag)
check.multipleDefaults(s.Body.List)
for i, c := range s.Body.List {
clause, _ := c.(*ast.CaseClause)
if clause == nil {
check.invalidAST(c.Pos(), "incorrect expression switch case")
continue
}
if x.mode != invalid {
check.caseValues(x, clause.List)
}
check.openScope(clause)
inner := inner
if i+1 < len(s.Body.List) {
inner |= fallthroughOk
}
check.stmtList(inner, clause.Body)
check.closeScope()
}
case *ast.TypeSwitchStmt:
inner |= inBreakable
check.openScope(s)
defer check.closeScope()
check.initStmt(s.Init)
// A type switch guard must be of the form:
//
// TypeSwitchGuard = [ identifier ":=" ] PrimaryExpr "." "(" "type" ")" .
//
// The parser is checking syntactic correctness;
// remaining syntactic errors are considered AST errors here.
// TODO(gri) better factoring of error handling (invalid ASTs)
//
var lhs *ast.Ident // lhs identifier or nil
var rhs ast.Expr
switch guard := s.Assign.(type) {
case *ast.ExprStmt:
rhs = guard.X
case *ast.AssignStmt:
if len(guard.Lhs) != 1 || guard.Tok != token.DEFINE || len(guard.Rhs) != 1 {
check.invalidAST(s.Pos(), "incorrect form of type switch guard")
return
}
lhs, _ = guard.Lhs[0].(*ast.Ident)
if lhs == nil {
check.invalidAST(s.Pos(), "incorrect form of type switch guard")
return
}
check.recordObject(lhs, nil) // lhs variable is implicitly declared in each cause clause
rhs = guard.Rhs[0]
default:
check.invalidAST(s.Pos(), "incorrect form of type switch guard")
return
}
// rhs must be of the form: expr.(type) and expr must be an interface
expr, _ := rhs.(*ast.TypeAssertExpr)
if expr == nil || expr.Type != nil {
check.invalidAST(s.Pos(), "incorrect form of type switch guard")
return
}
var x operand
check.expr(&x, expr.X)
if x.mode == invalid {
return
}
xtyp, _ := x.typ.Underlying().(*Interface)
if xtyp == nil {
check.errorf(x.pos(), "%s is not an interface", &x)
return
}
check.multipleDefaults(s.Body.List)
var lhsVars []*Var // set of implicitly declared lhs variables
seen := make(map[Type]token.Pos) // map of seen types to positions
for _, s := range s.Body.List {
clause, _ := s.(*ast.CaseClause)
if clause == nil {
check.invalidAST(s.Pos(), "incorrect type switch case")
continue
}
// Check each type in this type switch case.
T := check.caseTypes(&x, xtyp, clause.List, seen)
check.openScope(clause)
// If lhs exists, declare a corresponding variable in the case-local scope if necessary.
if lhs != nil {
// spec: "The TypeSwitchGuard may include a short variable declaration.
// When that form is used, the variable is declared at the beginning of
// the implicit block in each clause. In clauses with a case listing
// exactly one type, the variable has that type; otherwise, the variable
// has the type of the expression in the TypeSwitchGuard."
if len(clause.List) != 1 || T == nil {
T = x.typ
}
obj := NewVar(lhs.Pos(), check.pkg, lhs.Name, T)
// For the "declared but not used" error, all lhs variables act as
// one; i.e., if any one of them is 'used', all of them are 'used'.
// Collect them for later analysis.
lhsVars = append(lhsVars, obj)
check.declare(check.topScope, nil, obj)
check.recordImplicit(clause, obj)
}
check.stmtList(inner, clause.Body)
check.closeScope()
}
// If a lhs variable was declared but there were no case clauses, make sure
// we have at least one (dummy) 'unused' variable to force an error message.
if len(lhsVars) == 0 && lhs != nil {
lhsVars = []*Var{NewVar(lhs.Pos(), check.pkg, lhs.Name, x.typ)}
}
// Record lhs variables for this type switch, if any.
if len(lhsVars) > 0 {
check.lhsVarsList = append(check.lhsVarsList, lhsVars)
}
case *ast.SelectStmt:
inner |= inBreakable
check.multipleDefaults(s.Body.List)
for _, s := range s.Body.List {
clause, _ := s.(*ast.CommClause)
if clause == nil {
continue // error reported before
}
// clause.Comm must be a SendStmt, RecvStmt, or default case
valid := false
var rhs ast.Expr // rhs of RecvStmt, or nil
switch s := clause.Comm.(type) {
case nil, *ast.SendStmt:
valid = true
case *ast.AssignStmt:
if len(s.Rhs) == 1 {
rhs = s.Rhs[0]
}
case *ast.ExprStmt:
rhs = s.X
}
// if present, rhs must be a receive operation
if rhs != nil {
if x, _ := unparen(rhs).(*ast.UnaryExpr); x != nil && x.Op == token.ARROW {
valid = true
}
}
if !valid {
check.errorf(clause.Comm.Pos(), "select case must be send or receive (possibly with assignment)")
continue
}
check.openScope(s)
defer check.closeScope()
if clause.Comm != nil {
check.stmt(inner, clause.Comm)
}
check.stmtList(inner, clause.Body)
}
case *ast.ForStmt:
inner |= inBreakable | inContinuable
check.openScope(s)
defer check.closeScope()
check.initStmt(s.Init)
if s.Cond != nil {
var x operand
check.expr(&x, s.Cond)
if x.mode != invalid && !isBoolean(x.typ) {
check.errorf(s.Cond.Pos(), "non-boolean condition in for statement")
}
}
check.initStmt(s.Post)
check.stmt(inner, s.Body)
case *ast.RangeStmt:
inner |= inBreakable | inContinuable
check.openScope(s)
defer check.closeScope()
// check expression to iterate over
decl := s.Tok == token.DEFINE
var x operand
check.expr(&x, s.X)
if x.mode == invalid {
// if we don't have a declaration, we can still check the loop's body
// (otherwise we can't because we are missing the declared variables)
if !decl {
check.stmt(inner, s.Body)
}
return
}
// determine key/value types
var key, val Type
switch typ := x.typ.Underlying().(type) {
case *Basic:
if isString(typ) {
key = Typ[Int]
val = Typ[Rune]
}
case *Array:
key = Typ[Int]
val = typ.elem
case *Slice:
key = Typ[Int]
val = typ.elem
case *Pointer:
if typ, _ := typ.base.Underlying().(*Array); typ != nil {
key = Typ[Int]
val = typ.elem
}
case *Map:
key = typ.key
val = typ.elem
case *Chan:
key = typ.elem
val = Typ[Invalid]
if typ.dir&ast.RECV == 0 {
check.errorf(x.pos(), "cannot range over send-only channel %s", &x)
// ok to continue
}
if s.Value != nil {
check.errorf(s.Value.Pos(), "iteration over %s permits only one iteration variable", &x)
// ok to continue
}
}
if key == nil {
check.errorf(x.pos(), "cannot range over %s", &x)
// if we don't have a declaration, we can still check the loop's body
if !decl {
check.stmt(inner, s.Body)
}
return
}
// check assignment to/declaration of iteration variables
// (irregular assignment, cannot easily map to existing assignment checks)
if s.Key == nil {
check.invalidAST(s.Pos(), "range clause requires index iteration variable")
// ok to continue
}
// lhs expressions and initialization value (rhs) types
lhs := [2]ast.Expr{s.Key, s.Value}
rhs := [2]Type{key, val}
if decl {
// short variable declaration; variable scope starts after the range clause
// (the for loop opens a new scope, so variables on the lhs never redeclare
// previously declared variables)
var vars []*Var
for i, lhs := range lhs {
if lhs == nil {
continue
}
// determine lhs variable
var obj *Var
if ident, _ := lhs.(*ast.Ident); ident != nil {
// declare new variable
name := ident.Name
obj = NewVar(ident.Pos(), check.pkg, name, nil)
check.recordObject(ident, obj)
// _ variables don't count as new variables
if name != "_" {
vars = append(vars, obj)
}
} else {
check.errorf(lhs.Pos(), "cannot declare %s", lhs)
obj = NewVar(lhs.Pos(), check.pkg, "_", nil) // dummy variable
}
// initialize lhs variable
x.mode = value
x.expr = lhs // we don't have a better rhs expression to use here
x.typ = rhs[i]
check.initVar(obj, &x)
}
// declare variables
if len(vars) > 0 {
for _, obj := range vars {
check.declare(check.topScope, nil, obj) // recordObject already called
}
} else {
check.errorf(s.TokPos, "no new variables on left side of :=")
}
} else {
// ordinary assignment
for i, lhs := range lhs {
if lhs == nil {
continue
}
x.mode = value
x.expr = lhs // we don't have a better rhs expression to use here
x.typ = rhs[i]
check.assignVar(lhs, &x)
}
}
check.stmt(inner, s.Body)
default:
check.errorf(s.Pos(), "invalid statement")
}
}
func (check *Checker) openScope(s ast.Stmt, comment string) {
scope := NewScope(check.scope, s.Pos(), s.End(), comment)
check.recordScope(s, scope)
check.scope = scope
}
// Returns true if a separating semicolon is optional.
// Sets multiLine to true if the statements spans multiple lines.
func (p *printer) stmt(stmt ast.Stmt, multiLine *bool) (optSemi bool) {
p.print(stmt.Pos())
switch s := stmt.(type) {
case *ast.BadStmt:
p.print("BadStmt")
case *ast.DeclStmt:
p.decl(s.Decl, inStmtList, multiLine)
optSemi = true // decl prints terminating semicolon if necessary
case *ast.EmptyStmt:
// nothing to do
case *ast.LabeledStmt:
// a "correcting" unindent immediately following a line break
// is applied before the line break if there is no comment
// between (see writeWhitespace)
p.print(unindent)
p.expr(s.Label, multiLine)
p.print(token.COLON, vtab, indent)
p.linebreak(s.Stmt.Pos().Line, 0, 1, ignore, true)
optSemi = p.stmt(s.Stmt, multiLine)
case *ast.ExprStmt:
p.expr(s.X, multiLine)
case *ast.IncDecStmt:
p.expr(s.X, multiLine)
p.print(s.Tok)
case *ast.AssignStmt:
p.exprList(s.Pos(), s.Lhs, commaSep, multiLine)
p.print(blank, s.TokPos, s.Tok)
p.exprList(s.TokPos, s.Rhs, blankStart|commaSep, multiLine)
case *ast.GoStmt:
p.print(token.GO, blank)
p.expr(s.Call, multiLine)
case *ast.DeferStmt:
p.print(token.DEFER, blank)
p.expr(s.Call, multiLine)
case *ast.ReturnStmt:
p.print(token.RETURN)
if s.Results != nil {
p.exprList(s.Pos(), s.Results, blankStart|commaSep, multiLine)
}
case *ast.BranchStmt:
p.print(s.Tok)
if s.Label != nil {
p.print(blank)
p.expr(s.Label, multiLine)
}
case *ast.BlockStmt:
p.block(s, 1)
*multiLine = true
optSemi = true
case *ast.IfStmt:
p.print(token.IF)
p.controlClause(false, s.Init, s.Cond, nil)
p.block(s.Body, 1)
*multiLine = true
optSemi = true
if s.Else != nil {
p.print(blank, token.ELSE, blank)
switch s.Else.(type) {
case *ast.BlockStmt, *ast.IfStmt:
optSemi = p.stmt(s.Else, ignoreMultiLine)
default:
p.print(token.LBRACE, indent, formfeed)
p.stmt(s.Else, ignoreMultiLine)
p.print(unindent, formfeed, token.RBRACE)
}
}
case *ast.CaseClause:
if s.Values != nil {
p.print(token.CASE)
p.exprList(s.Pos(), s.Values, blankStart|commaSep, multiLine)
} else {
p.print(token.DEFAULT)
}
p.print(s.Colon, token.COLON)
p.stmtList(s.Body, 1)
optSemi = true // "block" without {}'s
case *ast.SwitchStmt:
p.print(token.SWITCH)
p.controlClause(false, s.Init, s.Tag, nil)
p.block(s.Body, 0)
*multiLine = true
optSemi = true
case *ast.TypeCaseClause:
if s.Types != nil {
p.print(token.CASE)
p.exprList(s.Pos(), s.Types, blankStart|commaSep, multiLine)
} else {
p.print(token.DEFAULT)
}
p.print(s.Colon, token.COLON)
p.stmtList(s.Body, 1)
optSemi = true // "block" without {}'s
case *ast.TypeSwitchStmt:
p.print(token.SWITCH)
if s.Init != nil {
p.print(blank)
p.stmt(s.Init, ignoreMultiLine)
p.print(token.SEMICOLON)
}
p.print(blank)
p.stmt(s.Assign, ignoreMultiLine)
p.print(blank)
p.block(s.Body, 0)
*multiLine = true
optSemi = true
case *ast.CommClause:
if s.Rhs != nil {
p.print(token.CASE, blank)
if s.Lhs != nil {
p.expr(s.Lhs, multiLine)
p.print(blank, s.Tok, blank)
}
p.expr(s.Rhs, multiLine)
} else {
p.print(token.DEFAULT)
}
p.print(s.Colon, token.COLON)
p.stmtList(s.Body, 1)
optSemi = true // "block" without {}'s
case *ast.SelectStmt:
p.print(token.SELECT, blank)
p.block(s.Body, 0)
*multiLine = true
optSemi = true
case *ast.ForStmt:
p.print(token.FOR)
p.controlClause(true, s.Init, s.Cond, s.Post)
p.block(s.Body, 1)
*multiLine = true
optSemi = true
case *ast.RangeStmt:
p.print(token.FOR, blank)
p.expr(s.Key, multiLine)
if s.Value != nil {
p.print(token.COMMA, blank)
p.expr(s.Value, multiLine)
}
p.print(blank, s.TokPos, s.Tok, blank, token.RANGE, blank)
p.expr(s.X, multiLine)
p.print(blank)
p.block(s.Body, 1)
*multiLine = true
optSemi = true
default:
panic("unreachable")
}
return
}
// stmt typechecks statement s.
func (check *checker) stmt(s ast.Stmt) {
switch s := s.(type) {
case *ast.BadStmt, *ast.EmptyStmt:
// ignore
case *ast.DeclStmt:
check.decl(s.Decl)
case *ast.LabeledStmt:
// TODO(gri) anything to do with label itself?
check.stmt(s.Stmt)
case *ast.ExprStmt:
var x operand
used := false
switch e := unparen(s.X).(type) {
case *ast.CallExpr:
// function calls are permitted
used = true
// but some builtins are excluded
check.expr(&x, e.Fun, nil, -1)
if x.mode != invalid {
if b, ok := x.typ.(*builtin); ok && !b.isStatement {
used = false
}
}
case *ast.UnaryExpr:
// receive operations are permitted
if e.Op == token.ARROW {
used = true
}
}
if !used {
check.errorf(s.Pos(), "%s not used", s.X)
// ok to continue
}
check.rawExpr(&x, s.X, nil, -1, false)
if x.mode == typexpr {
check.errorf(x.pos(), "%s is not an expression", x)
}
case *ast.SendStmt:
var ch, x operand
check.expr(&ch, s.Chan, nil, -1)
check.expr(&x, s.Value, nil, -1)
if ch.mode == invalid || x.mode == invalid {
return
}
if tch, ok := underlying(ch.typ).(*Chan); !ok || tch.Dir&ast.SEND == 0 || !x.isAssignable(tch.Elt) {
check.invalidOp(ch.pos(), "cannot send %s to channel %s", &x, &ch)
}
case *ast.IncDecStmt:
var op token.Token
switch s.Tok {
case token.INC:
op = token.ADD
case token.DEC:
op = token.SUB
default:
check.invalidAST(s.TokPos, "unknown inc/dec operation %s", s.Tok)
return
}
var x, y operand
check.expr(&x, s.X, nil, -1)
check.expr(&y, &ast.BasicLit{ValuePos: x.pos(), Kind: token.INT, Value: "1"}, nil, -1) // use x's position
check.binary(&x, &y, op, nil)
check.assign1to1(s.X, nil, &x, false, -1)
case *ast.AssignStmt:
switch s.Tok {
case token.ASSIGN, token.DEFINE:
if len(s.Lhs) == 0 {
check.invalidAST(s.Pos(), "missing lhs in assignment")
return
}
check.assignNtoM(s.Lhs, s.Rhs, s.Tok == token.DEFINE, -1)
default:
// assignment operations
if len(s.Lhs) != 1 || len(s.Rhs) != 1 {
check.errorf(s.TokPos, "assignment operation %s requires single-valued expressions", s.Tok)
return
}
// TODO(gri) make this conversion more efficient
var op token.Token
switch s.Tok {
case token.ADD_ASSIGN:
op = token.ADD
case token.SUB_ASSIGN:
op = token.SUB
case token.MUL_ASSIGN:
op = token.MUL
case token.QUO_ASSIGN:
op = token.QUO
case token.REM_ASSIGN:
op = token.REM
case token.AND_ASSIGN:
op = token.AND
case token.OR_ASSIGN:
op = token.OR
case token.XOR_ASSIGN:
op = token.XOR
case token.SHL_ASSIGN:
op = token.SHL
case token.SHR_ASSIGN:
op = token.SHR
case token.AND_NOT_ASSIGN:
op = token.AND_NOT
default:
check.invalidAST(s.TokPos, "unknown assignment operation %s", s.Tok)
return
}
var x, y operand
check.expr(&x, s.Lhs[0], nil, -1)
check.expr(&y, s.Rhs[0], nil, -1)
check.binary(&x, &y, op, nil)
check.assign1to1(s.Lhs[0], nil, &x, false, -1)
}
case *ast.GoStmt:
unimplemented()
case *ast.DeferStmt:
unimplemented()
case *ast.ReturnStmt:
sig := check.functypes[len(check.functypes)-1]
if n := len(sig.Results); n > 0 {
// TODO(gri) should not have to compute lhs, named every single time - clean this up
lhs := make([]ast.Expr, n)
named := false // if set, function has named results
for i, res := range sig.Results {
if len(res.Name) > 0 {
// a blank (_) result parameter is a named result parameter!
named = true
}
name := ast.NewIdent(res.Name)
name.NamePos = s.Pos()
name.Obj = res
lhs[i] = name
}
if len(s.Results) > 0 || !named {
// TODO(gri) assignNtoM should perhaps not require len(lhs) > 0
check.assignNtoM(lhs, s.Results, false, -1)
}
} else if len(s.Results) > 0 {
check.errorf(s.Pos(), "no result values expected")
}
case *ast.BranchStmt:
unimplemented()
case *ast.BlockStmt:
check.stmtList(s.List)
case *ast.IfStmt:
check.optionalStmt(s.Init)
var x operand
check.expr(&x, s.Cond, nil, -1)
if !isBoolean(x.typ) {
check.errorf(s.Cond.Pos(), "non-boolean condition in if statement")
}
check.stmt(s.Body)
check.optionalStmt(s.Else)
case *ast.SwitchStmt:
check.optionalStmt(s.Init)
var x operand
if s.Tag != nil {
check.expr(&x, s.Tag, nil, -1)
} else {
// TODO(gri) should provide a position (see IncDec) for good error messages
x.mode = constant
x.typ = Typ[UntypedBool]
x.val = true
}
for _, s := range s.Body.List {
if clause, ok := s.(*ast.CaseClause); ok {
for _, expr := range clause.List {
var y operand
check.expr(&y, expr, nil, -1)
// TODO(gri) x and y must be comparable
}
check.stmtList(clause.Body)
} else {
check.errorf(s.Pos(), "invalid AST: case clause expected")
}
}
case *ast.TypeSwitchStmt:
unimplemented()
case *ast.SelectStmt:
for _, s := range s.Body.List {
c, ok := s.(*ast.CommClause)
if !ok {
check.invalidAST(s.Pos(), "communication clause expected")
continue
}
check.optionalStmt(c.Comm) // TODO(gri) check correctness of c.Comm (must be Send/RecvStmt)
check.stmtList(c.Body)
}
case *ast.ForStmt:
check.optionalStmt(s.Init)
if s.Cond != nil {
var x operand
check.expr(&x, s.Cond, nil, -1)
if !isBoolean(x.typ) {
check.errorf(s.Cond.Pos(), "non-boolean condition in for statement")
}
}
check.optionalStmt(s.Post)
check.stmt(s.Body)
case *ast.RangeStmt:
unimplemented()
default:
check.errorf(s.Pos(), "invalid statement")
}
}
// stmt typechecks statement s.
func (check *Checker) stmt(ctxt stmtContext, s ast.Stmt) {
// statements cannot use iota in general
// (constant declarations set it explicitly)
assert(check.iota == nil)
// statements must end with the same top scope as they started with
if debug {
defer func(scope *Scope) {
// don't check if code is panicking
if p := recover(); p != nil {
panic(p)
}
assert(scope == check.scope)
}(check.scope)
}
inner := ctxt &^ fallthroughOk
switch s := s.(type) {
case *ast.BadStmt, *ast.EmptyStmt:
// ignore
case *ast.DeclStmt:
check.declStmt(s.Decl)
case *ast.LabeledStmt:
check.hasLabel = true
check.stmt(ctxt, s.Stmt)
case *ast.ExprStmt:
// spec: "With the exception of specific built-in functions,
// function and method calls and receive operations can appear
// in statement context. Such statements may be parenthesized."
var x operand
kind := check.rawExpr(&x, s.X, nil)
var msg string
switch x.mode {
default:
if kind == statement {
return
}
msg = "is not used"
case builtin:
msg = "must be called"
case typexpr:
msg = "is not an expression"
}
check.errorf(x.pos(), "%s %s", &x, msg)
case *ast.SendStmt:
var ch, x operand
check.expr(&ch, s.Chan)
check.expr(&x, s.Value)
if ch.mode == invalid || x.mode == invalid {
return
}
tch, ok := ch.typ.Underlying().(*Chan)
if !ok {
check.invalidOp(s.Arrow, "cannot send to non-chan type %s", ch.typ)
return
}
if tch.dir == RecvOnly {
check.invalidOp(s.Arrow, "cannot send to receive-only type %s", tch)
return
}
check.assignment(&x, tch.elem, "send")
case *ast.IncDecStmt:
var op token.Token
switch s.Tok {
case token.INC:
op = token.ADD
case token.DEC:
op = token.SUB
default:
check.invalidAST(s.TokPos, "unknown inc/dec operation %s", s.Tok)
return
}
var x operand
check.expr(&x, s.X)
if x.mode == invalid {
return
}
if !isNumeric(x.typ) {
check.invalidOp(s.X.Pos(), "%s%s (non-numeric type %s)", s.X, s.Tok, x.typ)
return
}
Y := &ast.BasicLit{ValuePos: s.X.Pos(), Kind: token.INT, Value: "1"} // use x's position
check.binary(&x, nil, s.X, Y, op)
if x.mode == invalid {
return
}
check.assignVar(s.X, &x)
case *ast.AssignStmt:
switch s.Tok {
case token.ASSIGN, token.DEFINE:
if len(s.Lhs) == 0 {
check.invalidAST(s.Pos(), "missing lhs in assignment")
return
}
if s.Tok == token.DEFINE {
check.shortVarDecl(s.TokPos, s.Lhs, s.Rhs)
} else {
// regular assignment
check.assignVars(s.Lhs, s.Rhs)
}
default:
// assignment operations
if len(s.Lhs) != 1 || len(s.Rhs) != 1 {
check.errorf(s.TokPos, "assignment operation %s requires single-valued expressions", s.Tok)
return
}
op := assignOp(s.Tok)
if op == token.ILLEGAL {
check.invalidAST(s.TokPos, "unknown assignment operation %s", s.Tok)
return
}
var x operand
check.binary(&x, nil, s.Lhs[0], s.Rhs[0], op)
if x.mode == invalid {
return
}
check.assignVar(s.Lhs[0], &x)
}
case *ast.GoStmt:
check.suspendedCall("go", s.Call)
case *ast.DeferStmt:
check.suspendedCall("defer", s.Call)
case *ast.ReturnStmt:
res := check.sig.results
if res.Len() > 0 {
// function returns results
// (if one, say the first, result parameter is named, all of them are named)
if len(s.Results) == 0 && res.vars[0].name != "" {
// spec: "Implementation restriction: A compiler may disallow an empty expression
// list in a "return" statement if a different entity (constant, type, or variable)
// with the same name as a result parameter is in scope at the place of the return."
for _, obj := range res.vars {
if _, alt := check.scope.LookupParent(obj.name, check.pos); alt != nil && alt != obj {
check.errorf(s.Pos(), "result parameter %s not in scope at return", obj.name)
check.errorf(alt.Pos(), "\tinner declaration of %s", obj)
// ok to continue
}
}
} else {
// return has results or result parameters are unnamed
check.initVars(res.vars, s.Results, s.Return)
}
} else if len(s.Results) > 0 {
check.error(s.Results[0].Pos(), "no result values expected")
check.use(s.Results...)
}
case *ast.BranchStmt:
if s.Label != nil {
check.hasLabel = true
return // checked in 2nd pass (check.labels)
}
switch s.Tok {
case token.BREAK:
if ctxt&breakOk == 0 {
check.error(s.Pos(), "break not in for, switch, or select statement")
}
case token.CONTINUE:
if ctxt&continueOk == 0 {
check.error(s.Pos(), "continue not in for statement")
}
case token.FALLTHROUGH:
if ctxt&fallthroughOk == 0 {
check.error(s.Pos(), "fallthrough statement out of place")
}
default:
check.invalidAST(s.Pos(), "branch statement: %s", s.Tok)
}
case *ast.BlockStmt:
check.openScope(s, "block")
defer check.closeScope()
check.stmtList(inner, s.List)
case *ast.IfStmt:
check.openScope(s, "if")
defer check.closeScope()
check.simpleStmt(s.Init)
var x operand
check.expr(&x, s.Cond)
if x.mode != invalid && !isBoolean(x.typ) {
check.error(s.Cond.Pos(), "non-boolean condition in if statement")
}
check.stmt(inner, s.Body)
// The parser produces a correct AST but if it was modified
// elsewhere the else branch may be invalid. Check again.
switch s.Else.(type) {
case nil, *ast.BadStmt:
// valid or error already reported
case *ast.IfStmt, *ast.BlockStmt:
check.stmt(inner, s.Else)
default:
check.error(s.Else.Pos(), "invalid else branch in if statement")
}
case *ast.SwitchStmt:
inner |= breakOk
check.openScope(s, "switch")
defer check.closeScope()
check.simpleStmt(s.Init)
var x operand
if s.Tag != nil {
check.expr(&x, s.Tag)
// By checking assignment of x to an invisible temporary
// (as a compiler would), we get all the relevant checks.
check.assignment(&x, nil, "switch expression")
} else {
// spec: "A missing switch expression is
// equivalent to the boolean value true."
x.mode = constant_
x.typ = Typ[Bool]
x.val = constant.MakeBool(true)
x.expr = &ast.Ident{NamePos: s.Body.Lbrace, Name: "true"}
}
check.multipleDefaults(s.Body.List)
seen := make(valueMap) // map of seen case values to positions and types
for i, c := range s.Body.List {
clause, _ := c.(*ast.CaseClause)
if clause == nil {
check.invalidAST(c.Pos(), "incorrect expression switch case")
continue
}
check.caseValues(&x, clause.List, seen)
check.openScope(clause, "case")
inner := inner
if i+1 < len(s.Body.List) {
inner |= fallthroughOk
}
check.stmtList(inner, clause.Body)
check.closeScope()
}
case *ast.TypeSwitchStmt:
inner |= breakOk
check.openScope(s, "type switch")
defer check.closeScope()
check.simpleStmt(s.Init)
// A type switch guard must be of the form:
//
// TypeSwitchGuard = [ identifier ":=" ] PrimaryExpr "." "(" "type" ")" .
//
// The parser is checking syntactic correctness;
// remaining syntactic errors are considered AST errors here.
// TODO(gri) better factoring of error handling (invalid ASTs)
//
var lhs *ast.Ident // lhs identifier or nil
var rhs ast.Expr
switch guard := s.Assign.(type) {
case *ast.ExprStmt:
rhs = guard.X
case *ast.AssignStmt:
if len(guard.Lhs) != 1 || guard.Tok != token.DEFINE || len(guard.Rhs) != 1 {
check.invalidAST(s.Pos(), "incorrect form of type switch guard")
return
}
lhs, _ = guard.Lhs[0].(*ast.Ident)
if lhs == nil {
check.invalidAST(s.Pos(), "incorrect form of type switch guard")
return
}
if lhs.Name == "_" {
// _ := x.(type) is an invalid short variable declaration
check.softErrorf(lhs.Pos(), "no new variable on left side of :=")
lhs = nil // avoid declared but not used error below
} else {
check.recordDef(lhs, nil) // lhs variable is implicitly declared in each cause clause
}
rhs = guard.Rhs[0]
default:
check.invalidAST(s.Pos(), "incorrect form of type switch guard")
return
}
// rhs must be of the form: expr.(type) and expr must be an interface
expr, _ := rhs.(*ast.TypeAssertExpr)
if expr == nil || expr.Type != nil {
check.invalidAST(s.Pos(), "incorrect form of type switch guard")
return
}
var x operand
check.expr(&x, expr.X)
if x.mode == invalid {
return
}
xtyp, _ := x.typ.Underlying().(*Interface)
if xtyp == nil {
check.errorf(x.pos(), "%s is not an interface", &x)
return
}
check.multipleDefaults(s.Body.List)
var lhsVars []*Var // list of implicitly declared lhs variables
seen := make(map[Type]token.Pos) // map of seen types to positions
for _, s := range s.Body.List {
clause, _ := s.(*ast.CaseClause)
if clause == nil {
check.invalidAST(s.Pos(), "incorrect type switch case")
continue
}
// Check each type in this type switch case.
T := check.caseTypes(&x, xtyp, clause.List, seen)
check.openScope(clause, "case")
// If lhs exists, declare a corresponding variable in the case-local scope.
if lhs != nil {
// spec: "The TypeSwitchGuard may include a short variable declaration.
// When that form is used, the variable is declared at the beginning of
// the implicit block in each clause. In clauses with a case listing
// exactly one type, the variable has that type; otherwise, the variable
// has the type of the expression in the TypeSwitchGuard."
if len(clause.List) != 1 || T == nil {
T = x.typ
}
obj := NewVar(lhs.Pos(), check.pkg, lhs.Name, T)
scopePos := clause.End()
if len(clause.Body) > 0 {
scopePos = clause.Body[0].Pos()
}
check.declare(check.scope, nil, obj, scopePos)
check.recordImplicit(clause, obj)
// For the "declared but not used" error, all lhs variables act as
// one; i.e., if any one of them is 'used', all of them are 'used'.
// Collect them for later analysis.
lhsVars = append(lhsVars, obj)
}
check.stmtList(inner, clause.Body)
check.closeScope()
}
// If lhs exists, we must have at least one lhs variable that was used.
if lhs != nil {
var used bool
for _, v := range lhsVars {
if v.used {
used = true
}
v.used = true // avoid usage error when checking entire function
}
if !used {
check.softErrorf(lhs.Pos(), "%s declared but not used", lhs.Name)
}
}
case *ast.SelectStmt:
inner |= breakOk
check.multipleDefaults(s.Body.List)
for _, s := range s.Body.List {
clause, _ := s.(*ast.CommClause)
if clause == nil {
continue // error reported before
}
// clause.Comm must be a SendStmt, RecvStmt, or default case
valid := false
var rhs ast.Expr // rhs of RecvStmt, or nil
switch s := clause.Comm.(type) {
case nil, *ast.SendStmt:
valid = true
case *ast.AssignStmt:
if len(s.Rhs) == 1 {
rhs = s.Rhs[0]
}
case *ast.ExprStmt:
rhs = s.X
}
// if present, rhs must be a receive operation
if rhs != nil {
if x, _ := unparen(rhs).(*ast.UnaryExpr); x != nil && x.Op == token.ARROW {
valid = true
}
}
if !valid {
check.error(clause.Comm.Pos(), "select case must be send or receive (possibly with assignment)")
continue
}
check.openScope(s, "case")
if clause.Comm != nil {
check.stmt(inner, clause.Comm)
}
check.stmtList(inner, clause.Body)
check.closeScope()
}
case *ast.ForStmt:
inner |= breakOk | continueOk
check.openScope(s, "for")
defer check.closeScope()
check.simpleStmt(s.Init)
if s.Cond != nil {
var x operand
check.expr(&x, s.Cond)
if x.mode != invalid && !isBoolean(x.typ) {
check.error(s.Cond.Pos(), "non-boolean condition in for statement")
}
}
check.simpleStmt(s.Post)
// spec: "The init statement may be a short variable
// declaration, but the post statement must not."
if s, _ := s.Post.(*ast.AssignStmt); s != nil && s.Tok == token.DEFINE {
check.softErrorf(s.Pos(), "cannot declare in post statement")
check.use(s.Lhs...) // avoid follow-up errors
}
check.stmt(inner, s.Body)
case *ast.RangeStmt:
inner |= breakOk | continueOk
check.openScope(s, "for")
defer check.closeScope()
// check expression to iterate over
var x operand
check.expr(&x, s.X)
// determine key/value types
var key, val Type
if x.mode != invalid {
switch typ := x.typ.Underlying().(type) {
case *Basic:
if isString(typ) {
key = Typ[Int]
val = universeRune // use 'rune' name
}
case *Array:
key = Typ[Int]
val = typ.elem
case *Slice:
key = Typ[Int]
val = typ.elem
case *Pointer:
if typ, _ := typ.base.Underlying().(*Array); typ != nil {
key = Typ[Int]
val = typ.elem
}
case *Map:
key = typ.key
val = typ.elem
case *Chan:
key = typ.elem
val = Typ[Invalid]
if typ.dir == SendOnly {
check.errorf(x.pos(), "cannot range over send-only channel %s", &x)
// ok to continue
}
if s.Value != nil {
check.errorf(s.Value.Pos(), "iteration over %s permits only one iteration variable", &x)
// ok to continue
}
}
}
if key == nil {
check.errorf(x.pos(), "cannot range over %s", &x)
// ok to continue
}
// check assignment to/declaration of iteration variables
// (irregular assignment, cannot easily map to existing assignment checks)
// lhs expressions and initialization value (rhs) types
lhs := [2]ast.Expr{s.Key, s.Value}
rhs := [2]Type{key, val} // key, val may be nil
if s.Tok == token.DEFINE {
// short variable declaration; variable scope starts after the range clause
// (the for loop opens a new scope, so variables on the lhs never redeclare
// previously declared variables)
var vars []*Var
for i, lhs := range lhs {
if lhs == nil {
continue
}
// determine lhs variable
var obj *Var
if ident, _ := lhs.(*ast.Ident); ident != nil {
// declare new variable
name := ident.Name
obj = NewVar(ident.Pos(), check.pkg, name, nil)
check.recordDef(ident, obj)
// _ variables don't count as new variables
if name != "_" {
vars = append(vars, obj)
}
} else {
check.errorf(lhs.Pos(), "cannot declare %s", lhs)
obj = NewVar(lhs.Pos(), check.pkg, "_", nil) // dummy variable
}
// initialize lhs variable
if typ := rhs[i]; typ != nil {
x.mode = value
x.expr = lhs // we don't have a better rhs expression to use here
x.typ = typ
check.initVar(obj, &x, "range clause")
} else {
obj.typ = Typ[Invalid]
obj.used = true // don't complain about unused variable
}
}
// declare variables
if len(vars) > 0 {
for _, obj := range vars {
// spec: "The scope of a constant or variable identifier declared inside
// a function begins at the end of the ConstSpec or VarSpec (ShortVarDecl
// for short variable declarations) and ends at the end of the innermost
// containing block."
scopePos := s.End()
check.declare(check.scope, nil /* recordDef already called */, obj, scopePos)
}
} else {
check.error(s.TokPos, "no new variables on left side of :=")
}
} else {
// ordinary assignment
for i, lhs := range lhs {
if lhs == nil {
continue
}
if typ := rhs[i]; typ != nil {
x.mode = value
x.expr = lhs // we don't have a better rhs expression to use here
x.typ = typ
check.assignVar(lhs, &x)
}
}
}
check.stmt(inner, s.Body)
default:
check.error(s.Pos(), "invalid statement")
}
}
// Sets multiLine to true if the statements spans multiple lines.
func (p *printer) stmt(stmt ast.Stmt, nextIsRBrace bool, multiLine *bool) {
p.print(stmt.Pos())
switch s := stmt.(type) {
case *ast.BadStmt:
p.print("BadStmt")
case *ast.DeclStmt:
p.decl(s.Decl, multiLine)
case *ast.EmptyStmt:
// nothing to do
case *ast.LabeledStmt:
// a "correcting" unindent immediately following a line break
// is applied before the line break if there is no comment
// between (see writeWhitespace)
p.print(unindent)
p.expr(s.Label, multiLine)
p.print(token.COLON, indent)
if e, isEmpty := s.Stmt.(*ast.EmptyStmt); isEmpty {
if !nextIsRBrace {
p.print(newline, e.Pos(), token.SEMICOLON)
break
}
} else {
p.linebreak(s.Stmt.Pos().Line, 1, ignore, true)
}
p.stmt(s.Stmt, nextIsRBrace, multiLine)
case *ast.ExprStmt:
const depth = 1
p.expr0(s.X, depth, multiLine)
case *ast.IncDecStmt:
const depth = 1
p.expr0(s.X, depth+1, multiLine)
p.print(s.Tok)
case *ast.AssignStmt:
var depth = 1
if len(s.Lhs) > 1 && len(s.Rhs) > 1 {
depth++
}
p.exprList(s.Pos(), s.Lhs, depth, commaSep, multiLine, s.TokPos)
p.print(blank, s.TokPos, s.Tok)
p.exprList(s.TokPos, s.Rhs, depth, blankStart|commaSep, multiLine, noPos)
case *ast.GoStmt:
p.print(token.GO, blank)
p.expr(s.Call, multiLine)
case *ast.DeferStmt:
p.print(token.DEFER, blank)
p.expr(s.Call, multiLine)
case *ast.ReturnStmt:
p.print(token.RETURN)
if s.Results != nil {
p.exprList(s.Pos(), s.Results, 1, blankStart|commaSep, multiLine, noPos)
}
case *ast.BranchStmt:
p.print(s.Tok)
if s.Label != nil {
p.print(blank)
p.expr(s.Label, multiLine)
}
case *ast.BlockStmt:
p.block(s, 1)
*multiLine = true
case *ast.IfStmt:
p.print(token.IF)
p.controlClause(false, s.Init, s.Cond, nil)
p.block(s.Body, 1)
*multiLine = true
if s.Else != nil {
p.print(blank, token.ELSE, blank)
switch s.Else.(type) {
case *ast.BlockStmt, *ast.IfStmt:
p.stmt(s.Else, nextIsRBrace, ignoreMultiLine)
default:
p.print(token.LBRACE, indent, formfeed)
p.stmt(s.Else, true, ignoreMultiLine)
p.print(unindent, formfeed, token.RBRACE)
}
}
case *ast.CaseClause:
if s.Values != nil {
p.print(token.CASE)
p.exprList(s.Pos(), s.Values, 1, blankStart|commaSep, multiLine, s.Colon)
} else {
p.print(token.DEFAULT)
}
p.print(s.Colon, token.COLON)
p.stmtList(s.Body, 1, nextIsRBrace)
case *ast.SwitchStmt:
p.print(token.SWITCH)
p.controlClause(false, s.Init, s.Tag, nil)
p.block(s.Body, 0)
*multiLine = true
case *ast.TypeCaseClause:
if s.Types != nil {
p.print(token.CASE)
p.exprList(s.Pos(), s.Types, 1, blankStart|commaSep, multiLine, s.Colon)
} else {
p.print(token.DEFAULT)
}
p.print(s.Colon, token.COLON)
p.stmtList(s.Body, 1, nextIsRBrace)
case *ast.TypeSwitchStmt:
p.print(token.SWITCH)
if s.Init != nil {
p.print(blank)
p.stmt(s.Init, false, ignoreMultiLine)
p.print(token.SEMICOLON)
}
p.print(blank)
p.stmt(s.Assign, false, ignoreMultiLine)
p.print(blank)
p.block(s.Body, 0)
*multiLine = true
case *ast.CommClause:
if s.Rhs != nil {
p.print(token.CASE, blank)
if s.Lhs != nil {
p.expr(s.Lhs, multiLine)
p.print(blank, s.Tok, blank)
}
p.expr(s.Rhs, multiLine)
} else {
p.print(token.DEFAULT)
}
p.print(s.Colon, token.COLON)
p.stmtList(s.Body, 1, nextIsRBrace)
case *ast.SelectStmt:
p.print(token.SELECT, blank)
p.block(s.Body, 0)
*multiLine = true
case *ast.ForStmt:
p.print(token.FOR)
p.controlClause(true, s.Init, s.Cond, s.Post)
p.block(s.Body, 1)
*multiLine = true
case *ast.RangeStmt:
p.print(token.FOR, blank)
p.expr(s.Key, multiLine)
if s.Value != nil {
p.print(token.COMMA, blank)
p.expr(s.Value, multiLine)
}
p.print(blank, s.TokPos, s.Tok, blank, token.RANGE, blank)
p.expr(stripParens(s.X), multiLine)
p.print(blank)
p.block(s.Body, 1)
*multiLine = true
default:
panic("unreachable")
}
return
}
// stmt typechecks statement s.
func (check *checker) stmt(s ast.Stmt, fallthroughOk bool) {
// statements cannot use iota in general
// (constant declarations set it explicitly)
assert(check.iota == nil)
switch s := s.(type) {
case *ast.BadStmt, *ast.EmptyStmt:
// ignore
case *ast.DeclStmt:
check.declStmt(s.Decl)
case *ast.LabeledStmt:
scope := check.labels
if scope == nil {
scope = NewScope(nil) // no label scope chain
check.labels = scope
}
label := s.Label
l := NewLabel(label.Pos(), label.Name)
// Labels are not resolved yet - mark them as used to avoid errors.
// TODO(gri) fix this
l.used = true
check.declareObj(scope, label, l)
check.stmt(s.Stmt, fallthroughOk)
case *ast.ExprStmt:
// spec: "With the exception of specific built-in functions,
// function and method calls and receive operations can appear
// in statement context. Such statements may be parenthesized."
var x operand
kind := check.rawExpr(&x, s.X, nil)
var msg string
switch x.mode {
default:
if kind == statement {
return
}
msg = "is not used"
case builtin:
msg = "must be called"
case typexpr:
msg = "is not an expression"
}
check.errorf(x.pos(), "%s %s", &x, msg)
case *ast.SendStmt:
var ch, x operand
check.expr(&ch, s.Chan)
check.expr(&x, s.Value)
if ch.mode == invalid || x.mode == invalid {
return
}
if tch, ok := ch.typ.Underlying().(*Chan); !ok || tch.dir&ast.SEND == 0 || !check.assignment(&x, tch.elt) {
if x.mode != invalid {
check.invalidOp(ch.pos(), "cannot send %s to channel %s", &x, &ch)
}
}
case *ast.IncDecStmt:
var op token.Token
switch s.Tok {
case token.INC:
op = token.ADD
case token.DEC:
op = token.SUB
default:
check.invalidAST(s.TokPos, "unknown inc/dec operation %s", s.Tok)
return
}
var x operand
Y := &ast.BasicLit{ValuePos: s.X.Pos(), Kind: token.INT, Value: "1"} // use x's position
check.binary(&x, s.X, Y, op)
if x.mode == invalid {
return
}
check.assignVar(s.X, &x)
case *ast.AssignStmt:
switch s.Tok {
case token.ASSIGN, token.DEFINE:
if len(s.Lhs) == 0 {
check.invalidAST(s.Pos(), "missing lhs in assignment")
return
}
if s.Tok == token.DEFINE {
check.shortVarDecl(s.Lhs, s.Rhs)
} else {
// regular assignment
check.assignVars(s.Lhs, s.Rhs)
}
default:
// assignment operations
if len(s.Lhs) != 1 || len(s.Rhs) != 1 {
check.errorf(s.TokPos, "assignment operation %s requires single-valued expressions", s.Tok)
return
}
op := assignOp(s.Tok)
if op == token.ILLEGAL {
check.invalidAST(s.TokPos, "unknown assignment operation %s", s.Tok)
return
}
var x operand
check.binary(&x, s.Lhs[0], s.Rhs[0], op)
if x.mode == invalid {
return
}
check.assignVar(s.Lhs[0], &x)
}
case *ast.GoStmt:
check.suspendedCall("go", s.Call)
case *ast.DeferStmt:
check.suspendedCall("defer", s.Call)
case *ast.ReturnStmt:
sig := check.funcSig
if n := sig.results.Len(); n > 0 {
// determine if the function has named results
named := false
lhs := make([]*Var, n)
for i, res := range sig.results.vars {
if res.name != "" {
// a blank (_) result parameter is a named result
named = true
}
lhs[i] = res
}
if len(s.Results) > 0 || !named {
check.initVars(lhs, s.Results, s.Return)
return
}
} else if len(s.Results) > 0 {
check.errorf(s.Pos(), "no result values expected")
}
case *ast.BranchStmt:
switch s.Tok {
case token.BREAK:
// TODO(gri) implement checks
case token.CONTINUE:
// TODO(gri) implement checks
case token.GOTO:
// TODO(gri) implement checks
case token.FALLTHROUGH:
if s.Label != nil {
check.invalidAST(s.Label.Pos(), "fallthrough statement cannot have label")
// ok to continue
}
if !fallthroughOk {
check.errorf(s.Pos(), "fallthrough statement out of place")
}
default:
check.invalidAST(s.Pos(), "unknown branch statement (%s)", s.Tok)
}
case *ast.BlockStmt:
check.openScope(s)
check.stmtList(s.List, false)
check.closeScope()
case *ast.IfStmt:
check.openScope(s)
check.optionalStmt(s.Init)
var x operand
check.expr(&x, s.Cond)
if x.mode != invalid && !isBoolean(x.typ) {
check.errorf(s.Cond.Pos(), "non-boolean condition in if statement")
}
check.stmt(s.Body, false)
check.optionalStmt(s.Else)
check.closeScope()
case *ast.SwitchStmt:
check.openScope(s)
check.optionalStmt(s.Init)
var x operand
tag := s.Tag
if tag == nil {
// use fake true tag value and position it at the opening { of the switch
ident := &ast.Ident{NamePos: s.Body.Lbrace, Name: "true"}
check.recordObject(ident, Universe.Lookup("true"))
tag = ident
}
check.expr(&x, tag)
check.multipleDefaults(s.Body.List)
// TODO(gri) check also correct use of fallthrough
seen := make(map[interface{}]token.Pos)
for i, c := range s.Body.List {
clause, _ := c.(*ast.CaseClause)
if clause == nil {
continue // error reported before
}
if x.mode != invalid {
for _, expr := range clause.List {
x := x // copy of x (don't modify original)
var y operand
check.expr(&y, expr)
if y.mode == invalid {
continue // error reported before
}
// If we have a constant case value, it must appear only
// once in the switch statement. Determine if there is a
// duplicate entry, but only report an error if there are
// no other errors.
var dupl token.Pos
var yy operand
if y.mode == constant {
// TODO(gri) This code doesn't work correctly for
// large integer, floating point, or
// complex values - the respective struct
// comparisons are shallow. Need to use a
// hash function to index the map.
dupl = seen[y.val]
seen[y.val] = y.pos()
yy = y // remember y
}
// TODO(gri) The convertUntyped call pair below appears in other places. Factor!
// Order matters: By comparing y against x, error positions are at the case values.
check.convertUntyped(&y, x.typ)
if y.mode == invalid {
continue // error reported before
}
check.convertUntyped(&x, y.typ)
if x.mode == invalid {
continue // error reported before
}
check.comparison(&y, &x, token.EQL)
if y.mode != invalid && dupl.IsValid() {
check.errorf(yy.pos(), "%s is duplicate case (previous at %s)",
&yy, check.fset.Position(dupl))
}
}
}
check.openScope(clause)
check.stmtList(clause.Body, i+1 < len(s.Body.List))
check.closeScope()
}
check.closeScope()
case *ast.TypeSwitchStmt:
check.openScope(s)
defer check.closeScope()
check.optionalStmt(s.Init)
// A type switch guard must be of the form:
//
// TypeSwitchGuard = [ identifier ":=" ] PrimaryExpr "." "(" "type" ")" .
//
// The parser is checking syntactic correctness;
// remaining syntactic errors are considered AST errors here.
// TODO(gri) better factoring of error handling (invalid ASTs)
//
var lhs *ast.Ident // lhs identifier or nil
var rhs ast.Expr
switch guard := s.Assign.(type) {
case *ast.ExprStmt:
rhs = guard.X
case *ast.AssignStmt:
if len(guard.Lhs) != 1 || guard.Tok != token.DEFINE || len(guard.Rhs) != 1 {
check.invalidAST(s.Pos(), "incorrect form of type switch guard")
return
}
lhs, _ = guard.Lhs[0].(*ast.Ident)
if lhs == nil {
check.invalidAST(s.Pos(), "incorrect form of type switch guard")
return
}
check.recordObject(lhs, nil) // lhs variable is implicitly declared in each cause clause
rhs = guard.Rhs[0]
default:
check.invalidAST(s.Pos(), "incorrect form of type switch guard")
return
}
// rhs must be of the form: expr.(type) and expr must be an interface
expr, _ := rhs.(*ast.TypeAssertExpr)
if expr == nil || expr.Type != nil {
check.invalidAST(s.Pos(), "incorrect form of type switch guard")
return
}
var x operand
check.expr(&x, expr.X)
if x.mode == invalid {
return
}
xtyp, _ := x.typ.Underlying().(*Interface)
if xtyp == nil {
check.errorf(x.pos(), "%s is not an interface", &x)
return
}
check.multipleDefaults(s.Body.List)
var lhsVars []*Var // set of implicitly declared lhs variables
for _, s := range s.Body.List {
clause, _ := s.(*ast.CaseClause)
if clause == nil {
continue // error reported before
}
// Check each type in this type switch case.
var T Type
for _, expr := range clause.List {
T = check.typOrNil(expr)
if T != nil && T != Typ[Invalid] {
check.typeAssertion(expr.Pos(), &x, xtyp, T)
}
}
check.openScope(clause)
// If lhs exists, declare a corresponding variable in the case-local scope if necessary.
if lhs != nil {
// spec: "The TypeSwitchGuard may include a short variable declaration.
// When that form is used, the variable is declared at the beginning of
// the implicit block in each clause. In clauses with a case listing
// exactly one type, the variable has that type; otherwise, the variable
// has the type of the expression in the TypeSwitchGuard."
if len(clause.List) != 1 || T == nil {
T = x.typ
}
obj := NewVar(lhs.Pos(), check.pkg, lhs.Name, T)
// For the "declared but not used" error, all lhs variables act as
// one; i.e., if any one of them is 'used', all of them are 'used'.
// Collect them for later analysis.
lhsVars = append(lhsVars, obj)
check.declareObj(check.topScope, nil, obj)
check.recordImplicit(clause, obj)
}
check.stmtList(clause.Body, false)
check.closeScope()
}
// If a lhs variable was declared but there were no case clauses, make sure
// we have at least one (dummy) 'unused' variable to force an error message.
if len(lhsVars) == 0 && lhs != nil {
lhsVars = []*Var{NewVar(lhs.Pos(), check.pkg, lhs.Name, x.typ)}
}
// Record lhs variables for this type switch, if any.
if len(lhsVars) > 0 {
check.lhsVarsList = append(check.lhsVarsList, lhsVars)
}
case *ast.SelectStmt:
check.multipleDefaults(s.Body.List)
for _, s := range s.Body.List {
clause, _ := s.(*ast.CommClause)
if clause == nil {
continue // error reported before
}
check.openScope(clause)
check.optionalStmt(clause.Comm) // TODO(gri) check correctness of c.Comm (must be Send/RecvStmt)
check.stmtList(clause.Body, false)
check.closeScope()
}
case *ast.ForStmt:
check.openScope(s)
check.optionalStmt(s.Init)
if s.Cond != nil {
var x operand
check.expr(&x, s.Cond)
if x.mode != invalid && !isBoolean(x.typ) {
check.errorf(s.Cond.Pos(), "non-boolean condition in for statement")
}
}
check.optionalStmt(s.Post)
check.stmt(s.Body, false)
check.closeScope()
case *ast.RangeStmt:
check.openScope(s)
defer check.closeScope()
// check expression to iterate over
decl := s.Tok == token.DEFINE
var x operand
check.expr(&x, s.X)
if x.mode == invalid {
// if we don't have a declaration, we can still check the loop's body
// (otherwise we can't because we are missing the declared variables)
if !decl {
check.stmt(s.Body, false)
}
return
}
// determine key/value types
var key, val Type
switch typ := x.typ.Underlying().(type) {
case *Basic:
if isString(typ) {
key = Typ[UntypedInt]
val = Typ[UntypedRune]
}
case *Array:
key = Typ[UntypedInt]
val = typ.elt
case *Slice:
key = Typ[UntypedInt]
val = typ.elt
case *Pointer:
if typ, _ := typ.base.Underlying().(*Array); typ != nil {
key = Typ[UntypedInt]
val = typ.elt
}
case *Map:
key = typ.key
val = typ.elt
case *Chan:
key = typ.elt
val = Typ[Invalid]
if typ.dir&ast.RECV == 0 {
check.errorf(x.pos(), "cannot range over send-only channel %s", &x)
// ok to continue
}
if s.Value != nil {
check.errorf(s.Value.Pos(), "iteration over %s permits only one iteration variable", &x)
// ok to continue
}
}
if key == nil {
check.errorf(x.pos(), "cannot range over %s", &x)
// if we don't have a declaration, we can still check the loop's body
if !decl {
check.stmt(s.Body, false)
}
return
}
// check assignment to/declaration of iteration variables
// (irregular assignment, cannot easily map to existing assignment checks)
if s.Key == nil {
check.invalidAST(s.Pos(), "range clause requires index iteration variable")
// ok to continue
}
// lhs expressions and initialization value (rhs) types
lhs := [2]ast.Expr{s.Key, s.Value}
rhs := [2]Type{key, val}
if decl {
// declaration; variable scope starts after the range clause
var idents []*ast.Ident
var vars []*Var
for i, lhs := range lhs {
if lhs == nil {
continue
}
// determine lhs variable
name := "_" // dummy, in case lhs is not an identifier
ident, _ := lhs.(*ast.Ident)
if ident != nil {
name = ident.Name
} else {
check.errorf(lhs.Pos(), "cannot declare %s", lhs)
}
idents = append(idents, ident)
obj := NewVar(lhs.Pos(), check.pkg, name, nil)
vars = append(vars, obj)
// initialize lhs variable
x.mode = value
x.expr = lhs // we don't have a better rhs expression to use here
x.typ = rhs[i]
check.initVar(obj, &x)
}
// declare variables
for i, ident := range idents {
check.declareObj(check.topScope, ident, vars[i])
}
} else {
// ordinary assignment
for i, lhs := range lhs {
if lhs == nil {
continue
}
x.mode = value
x.expr = lhs // we don't have a better rhs expression to use here
x.typ = rhs[i]
check.assignVar(lhs, &x)
}
}
check.stmt(s.Body, false)
default:
check.errorf(s.Pos(), "invalid statement")
}
}
func (v *StmtVisitor) VisitStmt(s ast.Stmt) {
var statements *[]ast.Stmt
switch s := s.(type) {
case *ast.BlockStmt:
statements = &s.List
case *ast.CaseClause:
statements = &s.Body
case *ast.CommClause:
statements = &s.Body
case *ast.ForStmt:
if s.Init != nil {
v.VisitStmt(s.Init)
}
if s.Post != nil {
v.VisitStmt(s.Post)
}
v.VisitStmt(s.Body)
case *ast.IfStmt:
if s.Init != nil {
v.VisitStmt(s.Init)
}
v.VisitStmt(s.Body)
if s.Else != nil {
// Code copied from go.tools/cmd/cover, to deal with "if x {} else if y {}"
const backupToElse = token.Pos(len("else ")) // The AST doesn't remember the else location. We can make an accurate guess.
switch stmt := s.Else.(type) {
case *ast.IfStmt:
block := &ast.BlockStmt{
Lbrace: stmt.If - backupToElse, // So the covered part looks like it starts at the "else".
List: []ast.Stmt{stmt},
Rbrace: stmt.End(),
}
s.Else = block
case *ast.BlockStmt:
stmt.Lbrace -= backupToElse // So the block looks like it starts at the "else".
default:
panic("unexpected node type in if")
}
v.VisitStmt(s.Else)
}
case *ast.LabeledStmt:
v.VisitStmt(s.Stmt)
case *ast.RangeStmt:
v.VisitStmt(s.Body)
case *ast.SelectStmt:
v.VisitStmt(s.Body)
case *ast.SwitchStmt:
if s.Init != nil {
v.VisitStmt(s.Init)
}
v.VisitStmt(s.Body)
case *ast.TypeSwitchStmt:
if s.Init != nil {
v.VisitStmt(s.Init)
}
v.VisitStmt(s.Assign)
v.VisitStmt(s.Body)
}
if statements == nil {
return
}
for i := 0; i < len(*statements); i++ {
s := (*statements)[i]
switch s.(type) {
case *ast.CaseClause, *ast.CommClause, *ast.BlockStmt:
break
default:
start, end := v.fset.Position(s.Pos()), v.fset.Position(s.End())
se := &StmtExtent{
startOffset: start.Offset,
startLine: start.Line,
startCol: start.Column,
endOffset: end.Offset,
endLine: end.Line,
endCol: end.Column,
}
v.function.stmts = append(v.function.stmts, se)
}
v.VisitStmt(s)
}
}
func (c *funcContext) translateStmt(stmt ast.Stmt, label *types.Label) {
c.SetPos(stmt.Pos())
stmt = filter.IncDecStmt(stmt, c.p.Info)
stmt = filter.Assign(stmt, c.p.Info)
switch s := stmt.(type) {
case *ast.BlockStmt:
c.translateStmtList(s.List)
case *ast.IfStmt:
if s.Init != nil {
c.translateStmt(s.Init, nil)
}
var caseClauses []ast.Stmt
ifStmt := s
for {
caseClauses = append(caseClauses, &ast.CaseClause{List: []ast.Expr{ifStmt.Cond}, Body: ifStmt.Body.List})
switch elseStmt := ifStmt.Else.(type) {
case *ast.IfStmt:
if elseStmt.Init != nil {
caseClauses = append(caseClauses, &ast.CaseClause{List: nil, Body: []ast.Stmt{elseStmt}})
break
}
ifStmt = elseStmt
continue
case *ast.BlockStmt:
caseClauses = append(caseClauses, &ast.CaseClause{List: nil, Body: elseStmt.List})
case *ast.EmptyStmt, nil:
// no else clause
default:
panic(fmt.Sprintf("Unhandled else: %T\n", elseStmt))
}
break
}
c.translateBranchingStmt(caseClauses, false, nil, nil, nil, c.Flattened[s])
case *ast.SwitchStmt:
if s.Init != nil {
c.translateStmt(s.Init, nil)
}
tag := s.Tag
if tag == nil {
tag = ast.NewIdent("true")
c.p.Types[tag] = types.TypeAndValue{Type: types.Typ[types.Bool], Value: exact.MakeBool(true)}
}
if c.p.Types[tag].Value == nil {
refVar := c.newVariable("_ref")
c.Printf("%s = %s;", refVar, c.translateExpr(tag))
tag = c.newIdent(refVar, c.p.Types[tag].Type)
}
translateCond := func(cond ast.Expr) *expression {
return c.translateExpr(&ast.BinaryExpr{
X: tag,
Op: token.EQL,
Y: cond,
})
}
c.translateBranchingStmt(s.Body.List, true, translateCond, nil, label, c.Flattened[s])
case *ast.TypeSwitchStmt:
if s.Init != nil {
c.translateStmt(s.Init, nil)
}
refVar := c.newVariable("_ref")
var expr ast.Expr
var printCaseBodyPrefix func(index int)
switch a := s.Assign.(type) {
case *ast.AssignStmt:
expr = a.Rhs[0].(*ast.TypeAssertExpr).X
printCaseBodyPrefix = func(index int) {
value := refVar
caseClause := s.Body.List[index].(*ast.CaseClause)
if len(caseClause.List) == 1 {
t := c.p.Types[caseClause.List[0]].Type
if _, isInterface := t.Underlying().(*types.Interface); !isInterface && !types.Identical(t, types.Typ[types.UntypedNil]) {
value += ".$val"
}
}
c.Printf("%s = %s;", c.objectName(c.p.Implicits[caseClause]), value)
}
case *ast.ExprStmt:
expr = a.X.(*ast.TypeAssertExpr).X
}
c.Printf("%s = %s;", refVar, c.translateExpr(expr))
translateCond := func(cond ast.Expr) *expression {
if types.Identical(c.p.Types[cond].Type, types.Typ[types.UntypedNil]) {
return c.formatExpr("%s === $ifaceNil", refVar)
}
return c.formatExpr("$assertType(%s, %s, true)[1]", refVar, c.typeName(c.p.Types[cond].Type))
}
c.translateBranchingStmt(s.Body.List, true, translateCond, printCaseBodyPrefix, label, c.Flattened[s])
case *ast.ForStmt:
if s.Init != nil {
c.translateStmt(s.Init, nil)
}
cond := func() string {
if s.Cond == nil {
return "true"
}
return c.translateExpr(s.Cond).String()
}
c.translateLoopingStmt(cond, s.Body, nil, func() {
if s.Post != nil {
c.translateStmt(s.Post, nil)
}
}, label, c.Flattened[s])
case *ast.RangeStmt:
refVar := c.newVariable("_ref")
c.Printf("%s = %s;", refVar, c.translateExpr(s.X))
switch t := c.p.Types[s.X].Type.Underlying().(type) {
case *types.Basic:
iVar := c.newVariable("_i")
c.Printf("%s = 0;", iVar)
runeVar := c.newVariable("_rune")
c.translateLoopingStmt(func() string { return iVar + " < " + refVar + ".length" }, s.Body, func() {
c.Printf("%s = $decodeRune(%s, %s);", runeVar, refVar, iVar)
if !isBlank(s.Key) {
c.Printf("%s", c.translateAssign(s.Key, iVar, types.Typ[types.Int], s.Tok == token.DEFINE))
}
if !isBlank(s.Value) {
c.Printf("%s", c.translateAssign(s.Value, runeVar+"[0]", types.Typ[types.Rune], s.Tok == token.DEFINE))
}
}, func() {
c.Printf("%s += %s[1];", iVar, runeVar)
}, label, c.Flattened[s])
case *types.Map:
iVar := c.newVariable("_i")
c.Printf("%s = 0;", iVar)
keysVar := c.newVariable("_keys")
c.Printf("%s = $keys(%s);", keysVar, refVar)
c.translateLoopingStmt(func() string { return iVar + " < " + keysVar + ".length" }, s.Body, func() {
entryVar := c.newVariable("_entry")
c.Printf("%s = %s[%s[%s]];", entryVar, refVar, keysVar, iVar)
c.translateStmt(&ast.IfStmt{
Cond: c.newIdent(entryVar+" === undefined", types.Typ[types.Bool]),
Body: &ast.BlockStmt{List: []ast.Stmt{&ast.BranchStmt{Tok: token.CONTINUE}}},
}, nil)
if !isBlank(s.Key) {
c.Printf("%s", c.translateAssign(s.Key, entryVar+".k", t.Key(), s.Tok == token.DEFINE))
}
if !isBlank(s.Value) {
c.Printf("%s", c.translateAssign(s.Value, entryVar+".v", t.Elem(), s.Tok == token.DEFINE))
}
}, func() {
c.Printf("%s++;", iVar)
}, label, c.Flattened[s])
case *types.Array, *types.Pointer, *types.Slice:
var length string
var elemType types.Type
switch t2 := t.(type) {
case *types.Array:
length = fmt.Sprintf("%d", t2.Len())
elemType = t2.Elem()
case *types.Pointer:
length = fmt.Sprintf("%d", t2.Elem().Underlying().(*types.Array).Len())
elemType = t2.Elem().Underlying().(*types.Array).Elem()
case *types.Slice:
length = refVar + ".$length"
elemType = t2.Elem()
}
iVar := c.newVariable("_i")
c.Printf("%s = 0;", iVar)
c.translateLoopingStmt(func() string { return iVar + " < " + length }, s.Body, func() {
if !isBlank(s.Key) {
c.Printf("%s", c.translateAssign(s.Key, iVar, types.Typ[types.Int], s.Tok == token.DEFINE))
}
if !isBlank(s.Value) {
c.Printf("%s", c.translateAssign(s.Value, c.translateImplicitConversion(c.setType(&ast.IndexExpr{
X: c.newIdent(refVar, t),
Index: c.newIdent(iVar, types.Typ[types.Int]),
}, elemType), elemType).String(), elemType, s.Tok == token.DEFINE))
}
}, func() {
c.Printf("%s++;", iVar)
}, label, c.Flattened[s])
case *types.Chan:
okVar := c.newIdent(c.newVariable("_ok"), types.Typ[types.Bool])
key := s.Key
tok := s.Tok
if key == nil {
key = ast.NewIdent("_")
tok = token.ASSIGN
}
forStmt := &ast.ForStmt{
Body: &ast.BlockStmt{
List: []ast.Stmt{
&ast.AssignStmt{
Lhs: []ast.Expr{
key,
okVar,
},
Rhs: []ast.Expr{
c.setType(&ast.UnaryExpr{X: c.newIdent(refVar, t), Op: token.ARROW}, types.NewTuple(types.NewVar(0, nil, "", t.Elem()), types.NewVar(0, nil, "", types.Typ[types.Bool]))),
},
Tok: tok,
},
&ast.IfStmt{
Cond: &ast.UnaryExpr{X: okVar, Op: token.NOT},
Body: &ast.BlockStmt{List: []ast.Stmt{&ast.BranchStmt{Tok: token.BREAK}}},
},
s.Body,
},
},
}
c.Flattened[forStmt] = true
c.translateStmt(forStmt, label)
default:
panic("")
}
case *ast.BranchStmt:
normalLabel := ""
blockingLabel := ""
data := c.flowDatas[nil]
if s.Label != nil {
normalLabel = " " + s.Label.Name
blockingLabel = " s" // use explicit label "s", because surrounding loop may not be flattened
data = c.flowDatas[c.p.Uses[s.Label].(*types.Label)]
}
switch s.Tok {
case token.BREAK:
c.PrintCond(data.endCase == 0, fmt.Sprintf("break%s;", normalLabel), fmt.Sprintf("$s = %d; continue%s;", data.endCase, blockingLabel))
case token.CONTINUE:
data.postStmt()
c.PrintCond(data.beginCase == 0, fmt.Sprintf("continue%s;", normalLabel), fmt.Sprintf("$s = %d; continue%s;", data.beginCase, blockingLabel))
case token.GOTO:
c.PrintCond(false, "goto "+s.Label.Name, fmt.Sprintf("$s = %d; continue;", c.labelCase(c.p.Uses[s.Label].(*types.Label))))
case token.FALLTHROUGH:
// handled in CaseClause
default:
panic("Unhandled branch statment: " + s.Tok.String())
}
case *ast.ReturnStmt:
results := s.Results
if c.resultNames != nil {
if len(s.Results) != 0 {
c.translateStmt(&ast.AssignStmt{
Lhs: c.resultNames,
Tok: token.ASSIGN,
Rhs: s.Results,
}, nil)
}
results = c.resultNames
}
c.Printf("return%s;", c.translateResults(results))
case *ast.DeferStmt:
isBuiltin := false
isJs := false
switch fun := s.Call.Fun.(type) {
case *ast.Ident:
var builtin *types.Builtin
builtin, isBuiltin = c.p.Uses[fun].(*types.Builtin)
if isBuiltin && builtin.Name() == "recover" {
c.Printf("$deferred.push([$recover, []]);")
return
}
case *ast.SelectorExpr:
isJs = typesutil.IsJsPackage(c.p.Uses[fun.Sel].Pkg())
}
sig := c.p.Types[s.Call.Fun].Type.Underlying().(*types.Signature)
args := c.translateArgs(sig, s.Call.Args, s.Call.Ellipsis.IsValid(), true)
if isBuiltin || isJs {
vars := make([]string, len(s.Call.Args))
callArgs := make([]ast.Expr, len(s.Call.Args))
for i, arg := range s.Call.Args {
v := c.newVariable("_arg")
vars[i] = v
callArgs[i] = c.newIdent(v, c.p.Types[arg].Type)
}
call := c.translateExpr(&ast.CallExpr{
Fun: s.Call.Fun,
Args: callArgs,
Ellipsis: s.Call.Ellipsis,
})
c.Printf("$deferred.push([function(%s) { %s; }, [%s]]);", strings.Join(vars, ", "), call, strings.Join(args, ", "))
return
}
c.Printf("$deferred.push([%s, [%s]]);", c.translateExpr(s.Call.Fun), strings.Join(args, ", "))
case *ast.AssignStmt:
if s.Tok != token.ASSIGN && s.Tok != token.DEFINE {
panic(s.Tok)
}
if s.Tok == token.DEFINE {
for _, lhs := range s.Lhs {
if !isBlank(lhs) {
obj := c.p.Defs[lhs.(*ast.Ident)]
if obj == nil {
obj = c.p.Uses[lhs.(*ast.Ident)]
}
c.setType(lhs, obj.Type())
}
}
}
switch {
case len(s.Lhs) == 1 && len(s.Rhs) == 1:
lhs := astutil.RemoveParens(s.Lhs[0])
if isBlank(lhs) {
if analysis.HasSideEffect(s.Rhs[0], c.p.Info.Info) {
c.Printf("%s;", c.translateExpr(s.Rhs[0]).String())
}
return
}
lhsType := c.p.Types[s.Lhs[0]].Type
c.Printf("%s", c.translateAssignOfExpr(lhs, s.Rhs[0], lhsType, s.Tok == token.DEFINE))
case len(s.Lhs) > 1 && len(s.Rhs) == 1:
tupleVar := c.newVariable("_tuple")
out := tupleVar + " = " + c.translateExpr(s.Rhs[0]).String() + ";"
tuple := c.p.Types[s.Rhs[0]].Type.(*types.Tuple)
for i, lhs := range s.Lhs {
lhs = astutil.RemoveParens(lhs)
if !isBlank(lhs) {
lhsType := c.p.Types[s.Lhs[i]].Type
out += " " + c.translateAssignOfExpr(lhs, c.newIdent(fmt.Sprintf("%s[%d]", tupleVar, i), tuple.At(i).Type()), lhsType, s.Tok == token.DEFINE)
}
}
c.Printf("%s", out)
case len(s.Lhs) == len(s.Rhs):
tmpVars := make([]string, len(s.Rhs))
var parts []string
for i, rhs := range s.Rhs {
tmpVars[i] = c.newVariable("_tmp")
if isBlank(astutil.RemoveParens(s.Lhs[i])) {
if analysis.HasSideEffect(rhs, c.p.Info.Info) {
c.Printf("%s;", c.translateExpr(rhs).String())
}
continue
}
lhsType := c.p.Types[s.Lhs[i]].Type
parts = append(parts, c.translateAssignOfExpr(c.newIdent(tmpVars[i], c.p.Types[s.Lhs[i]].Type), rhs, lhsType, true))
}
for i, lhs := range s.Lhs {
lhs = astutil.RemoveParens(lhs)
if !isBlank(lhs) {
t := c.p.Types[lhs].Type
parts = append(parts, c.translateAssignOfExpr(lhs, c.newIdent(tmpVars[i], t), t, s.Tok == token.DEFINE))
}
}
c.Printf("%s", strings.Join(parts, " "))
default:
panic("Invalid arity of AssignStmt.")
}
case *ast.DeclStmt:
decl := s.Decl.(*ast.GenDecl)
switch decl.Tok {
case token.VAR:
for _, spec := range s.Decl.(*ast.GenDecl).Specs {
valueSpec := spec.(*ast.ValueSpec)
lhs := make([]ast.Expr, len(valueSpec.Names))
for i, name := range valueSpec.Names {
lhs[i] = name
}
rhs := valueSpec.Values
isTuple := false
if len(rhs) == 1 {
_, isTuple = c.p.Types[rhs[0]].Type.(*types.Tuple)
}
for len(rhs) < len(lhs) && !isTuple {
rhs = append(rhs, nil)
}
c.translateStmt(&ast.AssignStmt{
Lhs: lhs,
Tok: token.DEFINE,
Rhs: rhs,
}, nil)
}
case token.TYPE:
for _, spec := range decl.Specs {
o := c.p.Defs[spec.(*ast.TypeSpec).Name].(*types.TypeName)
c.p.typeNames = append(c.p.typeNames, o)
c.p.objectNames[o] = c.newVariableWithLevel(o.Name(), true)
c.p.dependencies[o] = true
}
case token.CONST:
// skip, constants are inlined
}
case *ast.ExprStmt:
expr := c.translateExpr(s.X)
if expr != nil && expr.String() != "" {
c.Printf("%s;", expr)
}
case *ast.LabeledStmt:
label := c.p.Defs[s.Label].(*types.Label)
if c.GotoLabel[label] {
c.PrintCond(false, s.Label.Name+":", fmt.Sprintf("case %d:", c.labelCase(label)))
}
c.translateStmt(s.Stmt, label)
case *ast.GoStmt:
c.Printf("$go(%s, [%s]);", c.translateExpr(s.Call.Fun), strings.Join(c.translateArgs(c.p.Types[s.Call.Fun].Type.Underlying().(*types.Signature), s.Call.Args, s.Call.Ellipsis.IsValid(), false), ", "))
case *ast.SendStmt:
chanType := c.p.Types[s.Chan].Type.Underlying().(*types.Chan)
call := &ast.CallExpr{
Fun: c.newIdent("$send", types.NewSignature(nil, types.NewTuple(types.NewVar(0, nil, "", chanType), types.NewVar(0, nil, "", chanType.Elem())), nil, false)),
Args: []ast.Expr{s.Chan, s.Value},
}
c.Blocking[call] = true
c.translateStmt(&ast.ExprStmt{X: call}, label)
case *ast.SelectStmt:
var channels []string
var caseClauses []ast.Stmt
flattened := false
hasDefault := false
for i, s := range s.Body.List {
clause := s.(*ast.CommClause)
switch comm := clause.Comm.(type) {
case nil:
channels = append(channels, "[]")
hasDefault = true
case *ast.ExprStmt:
channels = append(channels, c.formatExpr("[%e]", astutil.RemoveParens(comm.X).(*ast.UnaryExpr).X).String())
case *ast.AssignStmt:
channels = append(channels, c.formatExpr("[%e]", astutil.RemoveParens(comm.Rhs[0]).(*ast.UnaryExpr).X).String())
case *ast.SendStmt:
channels = append(channels, c.formatExpr("[%e, %e]", comm.Chan, comm.Value).String())
default:
panic(fmt.Sprintf("unhandled: %T", comm))
}
indexLit := &ast.BasicLit{Kind: token.INT}
c.p.Types[indexLit] = types.TypeAndValue{Type: types.Typ[types.Int], Value: exact.MakeInt64(int64(i))}
caseClauses = append(caseClauses, &ast.CaseClause{
List: []ast.Expr{indexLit},
Body: clause.Body,
})
flattened = flattened || c.Flattened[clause]
}
selectCall := c.setType(&ast.CallExpr{
Fun: c.newIdent("$select", types.NewSignature(nil, types.NewTuple(types.NewVar(0, nil, "", types.NewInterface(nil, nil))), types.NewTuple(types.NewVar(0, nil, "", types.Typ[types.Int])), false)),
Args: []ast.Expr{c.newIdent(fmt.Sprintf("[%s]", strings.Join(channels, ", ")), types.NewInterface(nil, nil))},
}, types.Typ[types.Int])
c.Blocking[selectCall] = !hasDefault
selectionVar := c.newVariable("_selection")
c.Printf("%s = %s;", selectionVar, c.translateExpr(selectCall))
translateCond := func(cond ast.Expr) *expression {
return c.formatExpr("%s[0] === %e", selectionVar, cond)
}
printCaseBodyPrefix := func(index int) {
if assign, ok := s.Body.List[index].(*ast.CommClause).Comm.(*ast.AssignStmt); ok {
switch rhsType := c.p.Types[assign.Rhs[0]].Type.(type) {
case *types.Tuple:
c.translateStmt(&ast.AssignStmt{Lhs: assign.Lhs, Rhs: []ast.Expr{c.newIdent(selectionVar+"[1]", rhsType)}, Tok: assign.Tok}, nil)
default:
c.translateStmt(&ast.AssignStmt{Lhs: assign.Lhs, Rhs: []ast.Expr{c.newIdent(selectionVar+"[1][0]", rhsType)}, Tok: assign.Tok}, nil)
}
}
}
c.translateBranchingStmt(caseClauses, true, translateCond, printCaseBodyPrefix, label, flattened)
case *ast.EmptyStmt:
// skip
default:
panic(fmt.Sprintf("Unhandled statement: %T\n", s))
}
}
// checkStmt type checks a statement.
func (c *checker) checkStmt(s ast.Stmt) {
if debug {
fmt.Printf("Check statement: %T @ %s\n", s, c.fset.Position(s.Pos()))
}
switch s := s.(type) {
case *ast.AssignStmt:
// TODO Each left-hand side operand must be addressable,
// a map index expression, or the blank identifier. Operands
// may be parenthesized.
if len(s.Rhs) < len(s.Lhs) {
idents := make([]*ast.Ident, len(s.Lhs))
for i, e := range s.Lhs {
if ident, ok := e.(*ast.Ident); ok {
if ident.Obj != nil {
idents[i] = ident
}
} else {
c.checkExpr(e, nil)
}
}
c.checkExpr(s.Rhs[0], idents)
for _, ident := range idents {
if ident != nil {
maybeConvertUntyped(ident.Obj)
}
}
} else {
idents := make([]*ast.Ident, 1)
for i, e := range s.Rhs {
lhs := s.Lhs[i]
if ident, ok := lhs.(*ast.Ident); ok && ident.Obj != nil {
idents[0] = ident
rhstyp := c.checkExpr(e, idents)
if !maybeConvertUntyped(ident.Obj) {
lhstyp := ident.Obj.Type.(Type)
if _, untyped := rhstyp.(*Basic); untyped {
c.types[e] = lhstyp
}
}
} else {
lhstyp := c.checkExpr(lhs, nil)
rhstyp := c.checkExpr(e, nil)
if _, untyped := rhstyp.(*Basic); untyped {
c.types[e] = lhstyp
}
}
}
}
case *ast.BlockStmt:
for _, s := range s.List {
c.checkStmt(s)
}
case *ast.ExprStmt:
c.checkExpr(s.X, nil)
case *ast.BranchStmt:
// no-op
case *ast.DeclStmt:
// Only a GenDecl/ValueSpec is permissible in a statement.
decl := s.Decl.(*ast.GenDecl)
if decl.Tok == token.CONST {
c.decomposeRepeatConsts(decl)
}
for _, spec := range decl.Specs {
spec := spec.(*ast.ValueSpec)
for _, name := range spec.Names {
c.checkObj(name.Obj, true)
}
}
case *ast.EmptyStmt:
// no-op
case *ast.ForStmt:
if s.Init != nil {
c.checkStmt(s.Init)
}
// TODO make sure cond expr is some sort of bool.
if s.Cond != nil {
c.checkExpr(s.Cond, nil)
}
if s.Post != nil {
c.checkStmt(s.Post)
}
c.checkStmt(s.Body)
case *ast.GoStmt:
c.checkExpr(s.Call, nil)
case *ast.IfStmt:
if s.Init != nil {
c.checkStmt(s.Init)
}
// TODO make sure cond expr is some sort of bool.
c.checkExpr(s.Cond, nil)
c.checkStmt(s.Body)
if s.Else != nil {
c.checkStmt(s.Else)
}
case *ast.IncDecStmt:
// TODO check operand is addressable.
// TODO check operand type is suitable for inc/dec.
c.checkExpr(s.X, nil)
case *ast.LabeledStmt:
c.checkStmt(s.Stmt)
case *ast.RangeStmt:
var k, v Type
switch x := Underlying(c.checkExpr(s.X, nil)).(type) {
case *Pointer:
if x, ok := Underlying(x.Base).(*Array); ok {
k, v = Int, x.Elt
} else {
c.errorf(s.Pos(), "invalid type for range")
return
}
case *Array:
k, v = Int, x.Elt
case *Slice:
k, v = Int, x.Elt
case *Map:
k, v = x.Key, x.Elt
case *Chan:
k = x.Elt
if s.Value != nil {
c.errorf(s.Pos(), "too many variables in range")
return
}
case *Name:
if x != String {
c.errorf(s.Pos(), "invalid type for range")
return
}
k, v = Int, Rune
case *Basic:
if x.Kind != StringKind {
c.errorf(s.Pos(), "invalid type for range")
return
}
k, v = Int, Rune
default:
c.errorf(s.Pos(), "invalid type for range")
return
}
// TODO check key, value are addressable and assignable from range
// values.
if s.Key != nil {
if ident, ok := s.Key.(*ast.Ident); ok && ident.Obj != nil && ident.Obj.Type == nil {
ident.Obj.Type = k
} else {
c.checkExpr(s.Key, nil)
}
}
if s.Value != nil {
if ident, ok := s.Value.(*ast.Ident); ok && ident.Obj != nil && ident.Obj.Type == nil {
ident.Obj.Type = v
} else {
c.checkExpr(s.Value, nil)
}
}
c.checkStmt(s.Body)
case *ast.ReturnStmt:
// TODO we need to check the result type(s) against the
// current function's declared return type(s). We need
// context for that.
if c.function != nil {
// Propagate the return type of the current function
// so we implicitly convert constants.
if len(s.Results) == len(c.function.Results) {
for i, res := range c.function.Results {
c.types[s.Results[i]] = res.Type.(Type)
}
}
}
for _, e := range s.Results {
c.checkExpr(e, nil)
}
case *ast.SelectStmt:
if s.Body != nil {
for _, s_ := range s.Body.List {
cc := s_.(*ast.CommClause)
if cc.Comm != nil {
c.checkStmt(cc.Comm)
}
for _, s := range cc.Body {
c.checkStmt(s)
}
}
}
case *ast.SendStmt:
c.checkExpr(s.Chan, nil)
c.checkExpr(s.Value, nil)
case *ast.SwitchStmt:
if s.Init != nil {
c.checkStmt(s.Init)
}
tag := Bool.Underlying // omitted tag == "true"
if s.Tag != nil {
tag = c.checkExpr(s.Tag, nil)
}
for _, s_ := range s.Body.List {
cc := s_.(*ast.CaseClause)
for _, e := range cc.List {
// TODO check type is comparable to tag.
t := c.checkExpr(e, nil)
_, _ = t, tag
}
for _, s := range cc.Body {
c.checkStmt(s)
}
}
case *ast.TypeSwitchStmt:
if s.Init != nil {
c.checkStmt(s.Init)
}
var assignident *ast.Ident
var assigntyp Type
c.checkStmt(s.Assign)
if assign, ok := s.Assign.(*ast.AssignStmt); ok {
assignident = assign.Lhs[0].(*ast.Ident)
assigntyp = assignident.Obj.Type.(Type)
}
for _, s_ := range s.Body.List {
cc := s_.(*ast.CaseClause)
for _, e := range cc.List {
// TODO check expression is a type that could
// satisfy the interface.
if id, ok := e.(*ast.Ident); ok && id.Obj == Nil {
// ...
} else {
typ := c.makeType(e, true)
c.types[e] = typ
}
}
// In clauses with a case listing exactly one type, the variable
// has that type; otherwise, the variable has the type of the
// expression in the TypeSwitchGuard.
if assignident != nil {
if len(cc.List) == 1 {
assignident.Obj.Type = c.types[cc.List[0]]
} else {
assignident.Obj.Type = assigntyp
}
}
for _, s := range cc.Body {
c.checkStmt(s)
}
}
case *ast.DeferStmt:
c.checkExpr(s.Call, nil)
default:
panic(fmt.Sprintf("unimplemented %T", s))
}
}
func (c *funcContext) translateStmt(stmt ast.Stmt, label string) {
c.WritePos(stmt.Pos())
switch s := stmt.(type) {
case *ast.BlockStmt:
c.printLabel(label)
c.translateStmtList(s.List)
case *ast.IfStmt:
c.printLabel(label)
if s.Init != nil {
c.translateStmt(s.Init, "")
}
var caseClauses []ast.Stmt
ifStmt := s
for {
caseClauses = append(caseClauses, &ast.CaseClause{List: []ast.Expr{ifStmt.Cond}, Body: ifStmt.Body.List})
switch elseStmt := ifStmt.Else.(type) {
case *ast.IfStmt:
if elseStmt.Init != nil {
caseClauses = append(caseClauses, &ast.CaseClause{List: nil, Body: []ast.Stmt{elseStmt}})
break
}
ifStmt = elseStmt
continue
case *ast.BlockStmt:
caseClauses = append(caseClauses, &ast.CaseClause{List: nil, Body: elseStmt.List})
case *ast.EmptyStmt, nil:
// no else clause
default:
panic(fmt.Sprintf("Unhandled else: %T\n", elseStmt))
}
break
}
c.translateBranchingStmt(caseClauses, false, c.translateExpr, nil, "", c.flattened[s])
case *ast.SwitchStmt:
if s.Init != nil {
c.translateStmt(s.Init, "")
}
translateCond := func(cond ast.Expr) *expression {
return c.translateExpr(cond)
}
if s.Tag != nil {
refVar := c.newVariable("_ref")
c.Printf("%s = %s;", refVar, c.translateExpr(s.Tag))
translateCond = func(cond ast.Expr) *expression {
return c.translateExpr(&ast.BinaryExpr{
X: c.newIdent(refVar, c.p.info.Types[s.Tag].Type),
Op: token.EQL,
Y: cond,
})
}
}
c.translateBranchingStmt(s.Body.List, true, translateCond, nil, label, c.flattened[s])
case *ast.TypeSwitchStmt:
if s.Init != nil {
c.translateStmt(s.Init, "")
}
var expr ast.Expr
var typeSwitchVar string
switch a := s.Assign.(type) {
case *ast.AssignStmt:
expr = a.Rhs[0].(*ast.TypeAssertExpr).X
typeSwitchVar = c.newVariable(a.Lhs[0].(*ast.Ident).Name)
for _, caseClause := range s.Body.List {
c.p.objectVars[c.p.info.Implicits[caseClause]] = typeSwitchVar
}
case *ast.ExprStmt:
expr = a.X.(*ast.TypeAssertExpr).X
}
refVar := c.newVariable("_ref")
c.Printf("%s = %s;", refVar, c.translateExpr(expr))
translateCond := func(cond ast.Expr) *expression {
if types.Identical(c.p.info.Types[cond].Type, types.Typ[types.UntypedNil]) {
return c.formatExpr("%s === $ifaceNil", refVar)
}
return c.formatExpr("$assertType(%s, %s, true)[1]", refVar, c.typeName(c.p.info.Types[cond].Type))
}
printCaseBodyPrefix := func(index int) {
if typeSwitchVar == "" {
return
}
value := refVar
if conds := s.Body.List[index].(*ast.CaseClause).List; len(conds) == 1 {
t := c.p.info.Types[conds[0]].Type
if _, isInterface := t.Underlying().(*types.Interface); !isInterface && !types.Identical(t, types.Typ[types.UntypedNil]) {
value += ".$val"
}
}
c.Printf("%s = %s;", typeSwitchVar, value)
}
c.translateBranchingStmt(s.Body.List, true, translateCond, printCaseBodyPrefix, label, c.flattened[s])
case *ast.ForStmt:
if s.Init != nil {
c.translateStmt(s.Init, "")
}
cond := "true"
if s.Cond != nil {
cond = c.translateExpr(s.Cond).String()
}
c.translateLoopingStmt(cond, s.Body, nil, func() {
if s.Post != nil {
c.translateStmt(s.Post, "")
}
}, label, c.flattened[s])
case *ast.RangeStmt:
refVar := c.newVariable("_ref")
c.Printf("%s = %s;", refVar, c.translateExpr(s.X))
switch t := c.p.info.Types[s.X].Type.Underlying().(type) {
case *types.Basic:
iVar := c.newVariable("_i")
c.Printf("%s = 0;", iVar)
runeVar := c.newVariable("_rune")
c.translateLoopingStmt(iVar+" < "+refVar+".length", s.Body, func() {
c.Printf("%s = $decodeRune(%s, %s);", runeVar, refVar, iVar)
if !isBlank(s.Key) {
c.Printf("%s", c.translateAssign(s.Key, iVar, types.Typ[types.Int], s.Tok == token.DEFINE))
}
if !isBlank(s.Value) {
c.Printf("%s", c.translateAssign(s.Value, runeVar+"[0]", types.Typ[types.Rune], s.Tok == token.DEFINE))
}
}, func() {
c.Printf("%s += %s[1];", iVar, runeVar)
}, label, c.flattened[s])
case *types.Map:
iVar := c.newVariable("_i")
c.Printf("%s = 0;", iVar)
keysVar := c.newVariable("_keys")
c.Printf("%s = $keys(%s);", keysVar, refVar)
c.translateLoopingStmt(iVar+" < "+keysVar+".length", s.Body, func() {
entryVar := c.newVariable("_entry")
c.Printf("%s = %s[%s[%s]];", entryVar, refVar, keysVar, iVar)
if !isBlank(s.Key) {
c.Printf("%s", c.translateAssign(s.Key, entryVar+".k", t.Key(), s.Tok == token.DEFINE))
}
if !isBlank(s.Value) {
c.Printf("%s", c.translateAssign(s.Value, entryVar+".v", t.Elem(), s.Tok == token.DEFINE))
}
}, func() {
c.Printf("%s++;", iVar)
}, label, c.flattened[s])
case *types.Array, *types.Pointer, *types.Slice:
var length string
var elemType types.Type
switch t2 := t.(type) {
case *types.Array:
length = fmt.Sprintf("%d", t2.Len())
elemType = t2.Elem()
case *types.Pointer:
length = fmt.Sprintf("%d", t2.Elem().Underlying().(*types.Array).Len())
elemType = t2.Elem().Underlying().(*types.Array).Elem()
case *types.Slice:
length = refVar + ".$length"
elemType = t2.Elem()
}
iVar := c.newVariable("_i")
c.Printf("%s = 0;", iVar)
c.translateLoopingStmt(iVar+" < "+length, s.Body, func() {
if !isBlank(s.Key) {
c.Printf("%s", c.translateAssign(s.Key, iVar, types.Typ[types.Int], s.Tok == token.DEFINE))
}
if !isBlank(s.Value) {
c.Printf("%s", c.translateAssign(s.Value, c.translateImplicitConversion(c.setType(&ast.IndexExpr{
X: c.newIdent(refVar, t),
Index: c.newIdent(iVar, types.Typ[types.Int]),
}, elemType), elemType).String(), elemType, s.Tok == token.DEFINE))
}
}, func() {
c.Printf("%s++;", iVar)
}, label, c.flattened[s])
case *types.Chan:
okVar := c.newIdent(c.newVariable("_ok"), types.Typ[types.Bool])
forStmt := &ast.ForStmt{
Body: &ast.BlockStmt{
List: []ast.Stmt{
&ast.AssignStmt{
Lhs: []ast.Expr{
s.Key,
okVar,
},
Rhs: []ast.Expr{
c.setType(&ast.UnaryExpr{X: c.newIdent(refVar, t), Op: token.ARROW}, types.NewTuple(types.NewVar(0, nil, "", t.Elem()), types.NewVar(0, nil, "", types.Typ[types.Bool]))),
},
Tok: s.Tok,
},
&ast.IfStmt{
Cond: &ast.UnaryExpr{X: okVar, Op: token.NOT},
Body: &ast.BlockStmt{List: []ast.Stmt{&ast.BranchStmt{Tok: token.BREAK}}},
},
s.Body,
},
},
}
c.flattened[forStmt] = true
c.translateStmt(forStmt, label)
default:
panic("")
}
case *ast.BranchStmt:
c.printLabel(label)
labelSuffix := ""
data := c.flowDatas[""]
if s.Label != nil {
labelSuffix = " " + s.Label.Name
data = c.flowDatas[s.Label.Name]
}
switch s.Tok {
case token.BREAK:
c.PrintCond(data.endCase == 0, fmt.Sprintf("break%s;", labelSuffix), fmt.Sprintf("$s = %d; continue;", data.endCase))
case token.CONTINUE:
data.postStmt()
c.PrintCond(data.beginCase == 0, fmt.Sprintf("continue%s;", labelSuffix), fmt.Sprintf("$s = %d; continue;", data.beginCase))
case token.GOTO:
c.PrintCond(false, "goto "+s.Label.Name, fmt.Sprintf("$s = %d; continue;", c.labelCases[s.Label.Name]))
case token.FALLTHROUGH:
// handled in CaseClause
default:
panic("Unhandled branch statment: " + s.Tok.String())
}
case *ast.ReturnStmt:
c.printLabel(label)
results := s.Results
if c.resultNames != nil {
if len(s.Results) != 0 {
c.translateStmt(&ast.AssignStmt{
Lhs: c.resultNames,
Tok: token.ASSIGN,
Rhs: s.Results,
}, "")
}
results = c.resultNames
}
switch len(results) {
case 0:
c.Printf("return;")
case 1:
if c.sig.Results().Len() > 1 {
c.Printf("return %s;", c.translateExpr(results[0]))
return
}
v := c.translateImplicitConversion(results[0], c.sig.Results().At(0).Type())
c.delayedOutput = nil
c.Printf("return %s;", v)
default:
values := make([]string, len(results))
for i, result := range results {
values[i] = c.translateImplicitConversion(result, c.sig.Results().At(i).Type()).String()
}
c.delayedOutput = nil
c.Printf("return [%s];", strings.Join(values, ", "))
}
case *ast.DeferStmt:
c.printLabel(label)
isBuiltin := false
isJs := false
switch fun := s.Call.Fun.(type) {
case *ast.Ident:
var builtin *types.Builtin
builtin, isBuiltin = c.p.info.Uses[fun].(*types.Builtin)
if isBuiltin && builtin.Name() == "recover" {
c.Printf("$deferred.push([$recover, []]);")
return
}
case *ast.SelectorExpr:
isJs = isJsPackage(c.p.info.Uses[fun.Sel].Pkg())
}
if isBuiltin || isJs {
args := make([]ast.Expr, len(s.Call.Args))
for i, arg := range s.Call.Args {
args[i] = c.newIdent(c.newVariable("_arg"), c.p.info.Types[arg].Type)
}
call := c.translateExpr(&ast.CallExpr{
Fun: s.Call.Fun,
Args: args,
Ellipsis: s.Call.Ellipsis,
})
c.Printf("$deferred.push([function(%s) { %s; }, [%s]]);", strings.Join(c.translateExprSlice(args, nil), ", "), call, strings.Join(c.translateExprSlice(s.Call.Args, nil), ", "))
return
}
sig := c.p.info.Types[s.Call.Fun].Type.Underlying().(*types.Signature)
args := c.translateArgs(sig, s.Call.Args, s.Call.Ellipsis.IsValid())
if len(c.blocking) != 0 {
args = append(args, "true")
}
c.Printf("$deferred.push([%s, [%s]]);", c.translateExpr(s.Call.Fun), strings.Join(args, ", "))
case *ast.AssignStmt:
c.printLabel(label)
if s.Tok != token.ASSIGN && s.Tok != token.DEFINE {
var op token.Token
switch s.Tok {
case token.ADD_ASSIGN:
op = token.ADD
case token.SUB_ASSIGN:
op = token.SUB
case token.MUL_ASSIGN:
op = token.MUL
case token.QUO_ASSIGN:
op = token.QUO
case token.REM_ASSIGN:
op = token.REM
case token.AND_ASSIGN:
op = token.AND
case token.OR_ASSIGN:
op = token.OR
case token.XOR_ASSIGN:
op = token.XOR
case token.SHL_ASSIGN:
op = token.SHL
case token.SHR_ASSIGN:
op = token.SHR
case token.AND_NOT_ASSIGN:
op = token.AND_NOT
default:
panic(s.Tok)
}
var parts []string
lhs := s.Lhs[0]
switch l := lhs.(type) {
case *ast.IndexExpr:
lhsVar := c.newVariable("_lhs")
indexVar := c.newVariable("_index")
parts = append(parts, lhsVar+" = "+c.translateExpr(l.X).String()+";")
parts = append(parts, indexVar+" = "+c.translateExpr(l.Index).String()+";")
lhs = c.setType(&ast.IndexExpr{
X: c.newIdent(lhsVar, c.p.info.Types[l.X].Type),
Index: c.newIdent(indexVar, c.p.info.Types[l.Index].Type),
}, c.p.info.Types[l].Type)
case *ast.StarExpr:
lhsVar := c.newVariable("_lhs")
parts = append(parts, lhsVar+" = "+c.translateExpr(l.X).String()+";")
lhs = c.setType(&ast.StarExpr{
X: c.newIdent(lhsVar, c.p.info.Types[l.X].Type),
}, c.p.info.Types[l].Type)
case *ast.SelectorExpr:
v := hasCallVisitor{c.p.info, false}
ast.Walk(&v, l.X)
if v.hasCall {
lhsVar := c.newVariable("_lhs")
parts = append(parts, lhsVar+" = "+c.translateExpr(l.X).String()+";")
lhs = c.setType(&ast.SelectorExpr{
X: c.newIdent(lhsVar, c.p.info.Types[l.X].Type),
Sel: l.Sel,
}, c.p.info.Types[l].Type)
c.p.info.Selections[lhs.(*ast.SelectorExpr)] = c.p.info.Selections[l]
}
}
lhsType := c.p.info.Types[s.Lhs[0]].Type
parts = append(parts, c.translateAssign(lhs, c.translateExpr(c.setType(&ast.BinaryExpr{
X: lhs,
Op: op,
Y: c.setType(&ast.ParenExpr{X: s.Rhs[0]}, c.p.info.Types[s.Rhs[0]].Type),
}, lhsType)).String(), lhsType, s.Tok == token.DEFINE))
c.Printf("%s", strings.Join(parts, " "))
return
}
if s.Tok == token.DEFINE {
for _, lhs := range s.Lhs {
if !isBlank(lhs) {
obj := c.p.info.Defs[lhs.(*ast.Ident)]
if obj == nil {
obj = c.p.info.Uses[lhs.(*ast.Ident)]
}
c.setType(lhs, obj.Type())
}
}
}
switch {
case len(s.Lhs) == 1 && len(s.Rhs) == 1:
lhs := removeParens(s.Lhs[0])
if isBlank(lhs) {
v := hasCallVisitor{c.p.info, false}
ast.Walk(&v, s.Rhs[0])
if v.hasCall {
c.Printf("%s;", c.translateExpr(s.Rhs[0]).String())
}
return
}
lhsType := c.p.info.Types[s.Lhs[0]].Type
c.Printf("%s", c.translateAssignOfExpr(lhs, s.Rhs[0], lhsType, s.Tok == token.DEFINE))
case len(s.Lhs) > 1 && len(s.Rhs) == 1:
tupleVar := c.newVariable("_tuple")
out := tupleVar + " = " + c.translateExpr(s.Rhs[0]).String() + ";"
tuple := c.p.info.Types[s.Rhs[0]].Type.(*types.Tuple)
for i, lhs := range s.Lhs {
lhs = removeParens(lhs)
if !isBlank(lhs) {
lhsType := c.p.info.Types[s.Lhs[i]].Type
out += " " + c.translateAssignOfExpr(lhs, c.newIdent(fmt.Sprintf("%s[%d]", tupleVar, i), tuple.At(i).Type()), lhsType, s.Tok == token.DEFINE)
}
}
c.Printf("%s", out)
case len(s.Lhs) == len(s.Rhs):
tmpVars := make([]string, len(s.Rhs))
var parts []string
for i, rhs := range s.Rhs {
tmpVars[i] = c.newVariable("_tmp")
if isBlank(removeParens(s.Lhs[i])) {
v := hasCallVisitor{c.p.info, false}
ast.Walk(&v, rhs)
if v.hasCall {
c.Printf("%s;", c.translateExpr(rhs).String())
}
continue
}
lhsType := c.p.info.Types[s.Lhs[i]].Type
parts = append(parts, c.translateAssignOfExpr(c.newIdent(tmpVars[i], c.p.info.Types[s.Lhs[i]].Type), rhs, lhsType, true))
}
for i, lhs := range s.Lhs {
lhs = removeParens(lhs)
if !isBlank(lhs) {
parts = append(parts, c.translateAssign(lhs, tmpVars[i], c.p.info.Types[lhs].Type, s.Tok == token.DEFINE))
}
}
c.Printf("%s", strings.Join(parts, " "))
default:
panic("Invalid arity of AssignStmt.")
}
case *ast.IncDecStmt:
t := c.p.info.Types[s.X].Type
if iExpr, isIExpr := s.X.(*ast.IndexExpr); isIExpr {
switch u := c.p.info.Types[iExpr.X].Type.Underlying().(type) {
case *types.Array:
t = u.Elem()
case *types.Slice:
t = u.Elem()
case *types.Map:
t = u.Elem()
}
}
tok := token.ADD_ASSIGN
if s.Tok == token.DEC {
tok = token.SUB_ASSIGN
}
c.translateStmt(&ast.AssignStmt{
Lhs: []ast.Expr{s.X},
Tok: tok,
Rhs: []ast.Expr{c.newInt(1, t)},
}, label)
case *ast.DeclStmt:
c.printLabel(label)
decl := s.Decl.(*ast.GenDecl)
switch decl.Tok {
case token.VAR:
for _, spec := range s.Decl.(*ast.GenDecl).Specs {
valueSpec := spec.(*ast.ValueSpec)
lhs := make([]ast.Expr, len(valueSpec.Names))
for i, name := range valueSpec.Names {
lhs[i] = name
}
rhs := valueSpec.Values
isTuple := false
if len(rhs) == 1 {
_, isTuple = c.p.info.Types[rhs[0]].Type.(*types.Tuple)
}
for len(rhs) < len(lhs) && !isTuple {
rhs = append(rhs, nil)
}
c.translateStmt(&ast.AssignStmt{
Lhs: lhs,
Tok: token.DEFINE,
Rhs: rhs,
}, "")
}
case token.TYPE:
for _, spec := range decl.Specs {
o := c.p.info.Defs[spec.(*ast.TypeSpec).Name].(*types.TypeName)
c.translateType(o, false)
c.initType(o)
}
case token.CONST:
// skip, constants are inlined
}
case *ast.ExprStmt:
c.printLabel(label)
expr := c.translateExpr(s.X)
if expr != nil {
c.Printf("%s;", expr)
}
case *ast.LabeledStmt:
c.printLabel(label)
c.translateStmt(s.Stmt, s.Label.Name)
case *ast.GoStmt:
c.printLabel(label)
c.Printf("$go(%s, [%s]);", c.translateExpr(s.Call.Fun), strings.Join(c.translateArgs(c.p.info.Types[s.Call.Fun].Type.Underlying().(*types.Signature), s.Call.Args, s.Call.Ellipsis.IsValid()), ", "))
case *ast.SendStmt:
chanType := c.p.info.Types[s.Chan].Type.Underlying().(*types.Chan)
call := &ast.CallExpr{
Fun: c.newIdent("$send", types.NewSignature(nil, nil, types.NewTuple(types.NewVar(0, nil, "", chanType), types.NewVar(0, nil, "", chanType.Elem())), nil, false)),
Args: []ast.Expr{s.Chan, s.Value},
}
c.blocking[call] = true
c.translateStmt(&ast.ExprStmt{call}, label)
case *ast.SelectStmt:
var channels []string
var caseClauses []ast.Stmt
flattened := false
hasDefault := false
for i, s := range s.Body.List {
clause := s.(*ast.CommClause)
switch comm := clause.Comm.(type) {
case nil:
channels = append(channels, "[]")
hasDefault = true
case *ast.ExprStmt:
channels = append(channels, c.formatExpr("[%e]", removeParens(comm.X).(*ast.UnaryExpr).X).String())
case *ast.AssignStmt:
channels = append(channels, c.formatExpr("[%e]", removeParens(comm.Rhs[0]).(*ast.UnaryExpr).X).String())
case *ast.SendStmt:
channels = append(channels, c.formatExpr("[%e, %e]", comm.Chan, comm.Value).String())
default:
panic(fmt.Sprintf("unhandled: %T", comm))
}
caseClauses = append(caseClauses, &ast.CaseClause{
List: []ast.Expr{c.newInt(i, types.Typ[types.Int])},
Body: clause.Body,
})
flattened = flattened || c.flattened[clause]
}
selectCall := c.setType(&ast.CallExpr{
Fun: c.newIdent("$select", types.NewSignature(nil, nil, types.NewTuple(types.NewVar(0, nil, "", types.NewInterface(nil, nil))), types.NewTuple(types.NewVar(0, nil, "", types.Typ[types.Int])), false)),
Args: []ast.Expr{c.newIdent(fmt.Sprintf("[%s]", strings.Join(channels, ", ")), types.NewInterface(nil, nil))},
}, types.Typ[types.Int])
c.blocking[selectCall] = !hasDefault
selectionVar := c.newVariable("_selection")
c.Printf("%s = %s;", selectionVar, c.translateExpr(selectCall))
translateCond := func(cond ast.Expr) *expression {
return c.formatExpr("%s[0] === %e", selectionVar, cond)
}
printCaseBodyPrefix := func(index int) {
if assign, ok := s.Body.List[index].(*ast.CommClause).Comm.(*ast.AssignStmt); ok {
switch rhsType := c.p.info.Types[assign.Rhs[0]].Type.(type) {
case *types.Tuple:
c.translateStmt(&ast.AssignStmt{Lhs: assign.Lhs, Rhs: []ast.Expr{c.newIdent(selectionVar+"[1]", rhsType)}, Tok: assign.Tok}, "")
default:
c.translateStmt(&ast.AssignStmt{Lhs: assign.Lhs, Rhs: []ast.Expr{c.newIdent(selectionVar+"[1][0]", rhsType)}, Tok: assign.Tok}, "")
}
}
}
c.translateBranchingStmt(caseClauses, true, translateCond, printCaseBodyPrefix, label, flattened)
case *ast.EmptyStmt:
// skip
default:
panic(fmt.Sprintf("Unhandled statement: %T\n", s))
}
}
// findDead walks the statement looking for dead code.
// If d.reachable is false on entry, stmt itself is dead.
// When findDead returns, d.reachable tells whether the
// statement following stmt is reachable.
func (d *deadState) findDead(stmt ast.Stmt) {
// Is this a labeled goto target?
// If so, assume it is reachable due to the goto.
// This is slightly conservative, in that we don't
// check that the goto is reachable, so
// L: goto L
// will not provoke a warning.
// But it's good enough.
if x, isLabel := stmt.(*ast.LabeledStmt); isLabel && d.hasGoto[x.Label.Name] {
d.reachable = true
}
if !d.reachable {
switch stmt.(type) {
case *ast.EmptyStmt:
// do not warn about unreachable empty statements
default:
d.f.Bad(stmt.Pos(), "unreachable code")
d.reachable = true // silence error about next statement
}
}
switch x := stmt.(type) {
default:
d.f.Warnf(x.Pos(), "internal error in findDead: unexpected statement %T", x)
case *ast.AssignStmt,
*ast.BadStmt,
*ast.DeclStmt,
*ast.DeferStmt,
*ast.EmptyStmt,
*ast.GoStmt,
*ast.IncDecStmt,
*ast.SendStmt:
// no control flow
case *ast.BlockStmt:
for _, stmt := range x.List {
d.findDead(stmt)
}
case *ast.BranchStmt:
switch x.Tok {
case token.BREAK, token.GOTO, token.FALLTHROUGH:
d.reachable = false
case token.CONTINUE:
// NOTE: We accept "continue" statements as terminating.
// They are not necessary in the spec definition of terminating,
// because a continue statement cannot be the final statement
// before a return. But for the more general problem of syntactically
// identifying dead code, continue redirects control flow just
// like the other terminating statements.
d.reachable = false
}
case *ast.ExprStmt:
// Call to panic?
call, ok := x.X.(*ast.CallExpr)
if ok {
name, ok := call.Fun.(*ast.Ident)
if ok && name.Name == "panic" && name.Obj == nil {
d.reachable = false
}
}
case *ast.ForStmt:
d.findDead(x.Body)
d.reachable = x.Cond != nil || d.hasBreak[x]
case *ast.IfStmt:
d.findDead(x.Body)
if x.Else != nil {
r := d.reachable
d.reachable = true
d.findDead(x.Else)
d.reachable = d.reachable || r
} else {
// might not have executed if statement
d.reachable = true
}
case *ast.LabeledStmt:
d.findDead(x.Stmt)
case *ast.RangeStmt:
d.findDead(x.Body)
d.reachable = true
case *ast.ReturnStmt:
d.reachable = false
case *ast.SelectStmt:
// NOTE: Unlike switch and type switch below, we don't care
// whether a select has a default, because a select without a
// default blocks until one of the cases can run. That's different
// from a switch without a default, which behaves like it has
// a default with an empty body.
anyReachable := false
for _, comm := range x.Body.List {
d.reachable = true
for _, stmt := range comm.(*ast.CommClause).Body {
d.findDead(stmt)
}
anyReachable = anyReachable || d.reachable
}
d.reachable = anyReachable || d.hasBreak[x]
case *ast.SwitchStmt:
anyReachable := false
hasDefault := false
for _, cas := range x.Body.List {
cc := cas.(*ast.CaseClause)
if cc.List == nil {
hasDefault = true
}
d.reachable = true
for _, stmt := range cc.Body {
d.findDead(stmt)
}
anyReachable = anyReachable || d.reachable
}
d.reachable = anyReachable || d.hasBreak[x] || !hasDefault
case *ast.TypeSwitchStmt:
anyReachable := false
hasDefault := false
for _, cas := range x.Body.List {
cc := cas.(*ast.CaseClause)
if cc.List == nil {
hasDefault = true
}
d.reachable = true
for _, stmt := range cc.Body {
d.findDead(stmt)
}
anyReachable = anyReachable || d.reachable
}
d.reachable = anyReachable || d.hasBreak[x] || !hasDefault
}
}