func (ctxt *Context) visitExpr(f *ast.File, e ast.Expr, local bool, visitf func(*Info) bool) bool {
var info Info
info.Expr = e
switch e := e.(type) {
case *ast.Ident:
if e.Name == "_" {
return true
}
info.Pos = e.Pos()
info.Ident = e
case *ast.SelectorExpr:
info.Pos = e.Sel.Pos()
info.Ident = e.Sel
}
obj, t := types.ExprType(e, ctxt.importer)
if obj == nil {
ctxt.logf(e.Pos(), "no object for %s", pretty(e))
return true
}
info.ExprType = t
info.ReferObj = obj
if parser.Universe.Lookup(obj.Name) != obj {
info.ReferPos = types.DeclPos(obj)
if info.ReferPos == token.NoPos {
name := pretty(e)
if name != "init" {
ctxt.logf(e.Pos(), "no declaration for %s", pretty(e))
}
return true
}
} else {
info.Universe = true
}
info.Local = local
oldName := info.Ident.Name
more := visitf(&info)
if info.Ident.Name != oldName {
ctxt.ChangedFiles[ctxt.filename(f)] = f
}
return more
}
// Sets multiLine to true if the expression spans multiple lines.
func (p *printer) expr1(expr ast.Expr, prec1, depth int, multiLine *bool) {
p.print(expr.Pos())
switch x := expr.(type) {
case *ast.BadExpr:
p.print("BadExpr")
case *ast.Ident:
p.print(x)
case *ast.BinaryExpr:
if depth < 1 {
p.internalError("depth < 1:", depth)
depth = 1
}
p.binaryExpr(x, prec1, cutoff(x, depth), depth, multiLine)
case *ast.KeyValueExpr:
p.expr(x.Key, multiLine)
p.print(x.Colon, token.COLON, blank)
p.expr(x.Value, multiLine)
case *ast.StarExpr:
const prec = token.UnaryPrec
if prec < prec1 {
// parenthesis needed
p.print(token.LPAREN)
p.print(token.MUL)
p.expr(x.X, multiLine)
p.print(token.RPAREN)
} else {
// no parenthesis needed
p.print(token.MUL)
p.expr(x.X, multiLine)
}
case *ast.UnaryExpr:
const prec = token.UnaryPrec
if prec < prec1 {
// parenthesis needed
p.print(token.LPAREN)
p.expr(x, multiLine)
p.print(token.RPAREN)
} else {
// no parenthesis needed
p.print(x.Op)
if x.Op == token.RANGE {
// TODO(gri) Remove this code if it cannot be reached.
p.print(blank)
}
p.expr1(x.X, prec, depth, multiLine)
}
case *ast.BasicLit:
p.print(x)
case *ast.FuncLit:
p.expr(x.Type, multiLine)
p.funcBody(x.Body, p.distance(x.Type.Pos(), p.pos), true, multiLine)
case *ast.ParenExpr:
if _, hasParens := x.X.(*ast.ParenExpr); hasParens {
// don't print parentheses around an already parenthesized expression
// TODO(gri) consider making this more general and incorporate precedence levels
p.expr0(x.X, reduceDepth(depth), multiLine) // parentheses undo one level of depth
} else {
p.print(token.LPAREN)
p.expr0(x.X, reduceDepth(depth), multiLine) // parentheses undo one level of depth
p.print(x.Rparen, token.RPAREN)
}
case *ast.SelectorExpr:
parts := selectorExprList(expr)
p.exprList(token.NoPos, parts, depth, periodSep, multiLine, token.NoPos)
case *ast.TypeAssertExpr:
p.expr1(x.X, token.HighestPrec, depth, multiLine)
p.print(token.PERIOD, token.LPAREN)
if x.Type != nil {
p.expr(x.Type, multiLine)
} else {
p.print(token.TYPE)
}
p.print(token.RPAREN)
case *ast.IndexExpr:
// TODO(gri): should treat[] like parentheses and undo one level of depth
p.expr1(x.X, token.HighestPrec, 1, multiLine)
p.print(x.Lbrack, token.LBRACK)
p.expr0(x.Index, depth+1, multiLine)
p.print(x.Rbrack, token.RBRACK)
case *ast.SliceExpr:
// TODO(gri): should treat[] like parentheses and undo one level of depth
p.expr1(x.X, token.HighestPrec, 1, multiLine)
p.print(x.Lbrack, token.LBRACK)
if x.Low != nil {
p.expr0(x.Low, depth+1, multiLine)
}
// blanks around ":" if both sides exist and either side is a binary expression
if depth <= 1 && x.Low != nil && x.High != nil && (isBinary(x.Low) || isBinary(x.High)) {
p.print(blank, token.COLON, blank)
} else {
p.print(token.COLON)
}
if x.High != nil {
p.expr0(x.High, depth+1, multiLine)
}
p.print(x.Rbrack, token.RBRACK)
case *ast.CallExpr:
if len(x.Args) > 1 {
depth++
}
p.expr1(x.Fun, token.HighestPrec, depth, multiLine)
p.print(x.Lparen, token.LPAREN)
p.exprList(x.Lparen, x.Args, depth, commaSep|commaTerm, multiLine, x.Rparen)
if x.Ellipsis.IsValid() {
p.print(x.Ellipsis, token.ELLIPSIS)
}
p.print(x.Rparen, token.RPAREN)
case *ast.CompositeLit:
// composite literal elements that are composite literals themselves may have the type omitted
if x.Type != nil {
p.expr1(x.Type, token.HighestPrec, depth, multiLine)
}
p.print(x.Lbrace, token.LBRACE)
p.exprList(x.Lbrace, x.Elts, 1, commaSep|commaTerm, multiLine, x.Rbrace)
// do not insert extra line breaks because of comments before
// the closing '}' as it might break the code if there is no
// trailing ','
p.print(noExtraLinebreak, x.Rbrace, token.RBRACE, noExtraLinebreak)
case *ast.Ellipsis:
p.print(token.ELLIPSIS)
if x.Elt != nil {
p.expr(x.Elt, multiLine)
}
case *ast.ArrayType:
p.print(token.LBRACK)
if x.Len != nil {
p.expr(x.Len, multiLine)
}
p.print(token.RBRACK)
p.expr(x.Elt, multiLine)
case *ast.StructType:
p.print(token.STRUCT)
p.fieldList(x.Fields, true, x.Incomplete)
case *ast.FuncType:
p.print(token.FUNC)
p.signature(x.Params, x.Results, multiLine)
case *ast.InterfaceType:
p.print(token.INTERFACE)
p.fieldList(x.Methods, false, x.Incomplete)
case *ast.MapType:
p.print(token.MAP, token.LBRACK)
p.expr(x.Key, multiLine)
p.print(token.RBRACK)
p.expr(x.Value, multiLine)
case *ast.ChanType:
switch x.Dir {
case ast.SEND | ast.RECV:
p.print(token.CHAN)
case ast.RECV:
p.print(token.ARROW, token.CHAN)
case ast.SEND:
p.print(token.CHAN, token.ARROW)
}
p.print(blank)
p.expr(x.Value, multiLine)
default:
panic("unreachable")
}
return
}
func checkExprs(t *testing.T, pkg *ast.File, importer Importer) {
var visit astVisitor
stopped := false
visit = func(n ast.Node) bool {
if stopped {
return false
}
mustResolve := false
var e ast.Expr
switch n := n.(type) {
case *ast.ImportSpec:
// If the file imports a package to ".", abort
// because we don't support that (yet).
if n.Name != nil && n.Name.Name == "." {
stopped = true
return false
}
return true
case *ast.FuncDecl:
// add object for init functions
if n.Recv == nil && n.Name.Name == "init" {
n.Name.Obj = ast.NewObj(ast.Fun, "init")
}
return true
case *ast.Ident:
if n.Name == "_" {
return false
}
e = n
mustResolve = true
case *ast.KeyValueExpr:
// don't try to resolve the key part of a key-value
// because it might be a map key which doesn't
// need resolving, and we can't tell without being
// complicated with types.
ast.Walk(visit, n.Value)
return false
case *ast.SelectorExpr:
ast.Walk(visit, n.X)
e = n
mustResolve = true
case *ast.File:
for _, d := range n.Decls {
ast.Walk(visit, d)
}
return false
case ast.Expr:
e = n
default:
return true
}
defer func() {
if err := recover(); err != nil {
t.Fatalf("panic (%v) on %T", err, e)
//t.Fatalf("panic (%v) on %v at %v\n", err, e, FileSet.Position(e.Pos()))
}
}()
obj, _ := ExprType(e, importer)
if obj == nil && mustResolve {
t.Errorf("no object for %v(%p, %T) at %v\n", e, e, e, FileSet.Position(e.Pos()))
}
return false
}
ast.Walk(visit, pkg)
}