// parseOperand may return an expression or a raw type (incl. array
// types of the form [...]T. Callers must verify the result.
// If lhs is set and the result is an identifier, it is not resolved.
//
func (p *parser) parseOperand(lhs bool) ast.Expr {
switch p.tok {
case token.IDENT:
x := p.parseIdent()
// if !lhs {
// p.resolve(x)
// }
return x
case token.INT, token.FLOAT, token.IMAG, token.CHAR, token.STRING:
x := &ast.BasicLit{ValuePos: p.pos, Kind: p.tok, Value: p.lit}
p.next()
return x
case token.LPAREN:
lparen := p.pos
p.next()
p.exprLev++
x := p.parseOperand(false)
p.exprLev--
rparen := p.expect(token.RPAREN)
return &ast.ParenExpr{Lparen: lparen, X: x, Rparen: rparen}
default:
p.errorExpected(p.pos, "operand")
return &ast.BadExpr{From: p.pos - 10, To: p.pos + 10}
}
}
func (p *parser) expect(tok token.Token) token.Pos {
pos := p.pos
if p.tok != tok {
p.errorExpected(pos, "'"+tok.String()+"'")
}
p.next() // make progress
return pos
}
func (p *parser) init(fset *token.FileSet, filename string, src []byte) {
p.file = fset.AddFile(filename, -1, len(src))
var m scanner.Mode
eh := func(pos token.Position, msg string) { p.errors.Add(pos, msg) }
p.scanner.Init(p.file, src, eh, m)
p.next()
}
func (p *parser) parseIdent() *ast.Ident {
pos := p.pos
name := "_"
if p.tok == token.IDENT {
name = p.lit
p.next()
} else {
p.expect(token.IDENT) // use expect() error handling
}
return &ast.Ident{NamePos: pos, Name: name}
}