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(), s.End()}
}
// 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(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.fset.Position(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.SendStmt:
const depth = 1
p.expr0(s.Chan, depth, multiLine)
p.print(blank, s.Arrow, token.ARROW, blank)
p.expr0(s.Value, depth, multiLine)
case *ast.IncDecStmt:
const depth = 1
p.expr0(s.X, depth+1, multiLine)
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, commaSep, multiLine, s.TokPos)
p.print(blank, s.TokPos, s.Tok)
p.exprList(s.TokPos, s.Rhs, depth, blankStart|commaSep, multiLine, token.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:
*multiLine = false
p.print(token.RETURN)
if s.Results != nil {
p.exprList(s.Pos(), s.Results, 1, blankStart|commaSep, multiLine, token.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.Comm != nil {
p.print(token.CASE, blank)
p.stmt(s.Comm, false, ignoreMultiLine)
} 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
}
func (p *parser) parseForStmt() ast.Stmt {
if p.trace {
defer un(trace(p, "ForStmt"))
}
pos := p.expect(token.FOR)
var s1, s2, s3 ast.Stmt
if p.tok != token.LBRACE {
prevLev := p.exprLev
p.exprLev = -1
if p.tok != token.SEMICOLON {
s2 = p.parseSimpleStmt(false)
}
if p.tok == token.SEMICOLON {
p.next()
s1 = s2
s2 = nil
if p.tok != token.SEMICOLON {
s2 = p.parseSimpleStmt(false)
}
p.expectSemi()
if p.tok != token.LBRACE {
s3 = p.parseSimpleStmt(false)
}
}
p.exprLev = prevLev
}
body := p.parseBlockStmt()
p.expectSemi()
if as, isAssign := s2.(*ast.AssignStmt); isAssign {
// possibly a for statement with a range clause; check assignment operator
if as.Tok != token.ASSIGN && as.Tok != token.DEFINE {
p.errorExpected(as.TokPos, "'=' or ':='")
return &ast.BadStmt{pos, body.End()}
}
// check lhs
var key, value ast.Expr
switch len(as.Lhs) {
case 2:
key, value = as.Lhs[0], as.Lhs[1]
case 1:
key = as.Lhs[0]
default:
p.errorExpected(as.Lhs[0].Pos(), "1 or 2 expressions")
return &ast.BadStmt{pos, body.End()}
}
// check rhs
if len(as.Rhs) != 1 {
p.errorExpected(as.Rhs[0].Pos(), "1 expression")
return &ast.BadStmt{pos, body.End()}
}
if rhs, isUnary := as.Rhs[0].(*ast.UnaryExpr); isUnary && rhs.Op == token.RANGE {
// rhs is range expression; check lhs
return &ast.RangeStmt{pos, key, value, as.TokPos, as.Tok, rhs.X, body}
} else {
p.errorExpected(s2.Pos(), "range clause")
return &ast.BadStmt{pos, body.End()}
}
} else {
// regular for statement
return &ast.ForStmt{pos, s1, p.makeExpr(s2), s3, body}
}
panic("unreachable")
}