func (p *gcParser) expect(tok int) string {
lit := p.lit
if p.tok != tok {
p.errorf("expected %q, got %q (%q)", scanner.TokenString(tok), scanner.TokenString(p.tok), lit)
}
p.next()
return lit
}
// Export = "PackageClause { Decl } "$$" .
// PackageClause = "package" identifier [ "safe" ] "\n" .
//
func (p *gcParser) parseExport() *ast.Object {
p.expectKeyword("package")
name := p.expect(scanner.Ident)
if p.tok != '\n' {
// A package is safe if it was compiled with the -u flag,
// which disables the unsafe package.
// TODO(gri) remember "safe" package
p.expectKeyword("safe")
}
p.expect('\n')
assert(p.imports[p.id] == nil)
pkg := ast.NewObj(ast.Pkg, name)
pkg.Data = ast.NewScope(nil)
p.imports[p.id] = pkg
for p.tok != '$' && p.tok != scanner.EOF {
p.parseDecl()
}
if ch := p.scanner.Peek(); p.tok != '$' || ch != '$' {
// don't call next()/expect() since reading past the
// export data may cause scanner errors (e.g. NUL chars)
p.errorf("expected '$$', got %s %c", scanner.TokenString(p.tok), ch)
}
if n := p.scanner.ErrorCount; n != 0 {
p.errorf("expected no scanner errors, got %d", n)
}
return pkg
}
func (p *parser) expect(tok rune) scanner.Position {
pos := p.pos
if p.tok != tok {
p.errorExpected(pos, scanner.TokenString(tok))
}
p.next() // make progress in any case
return pos
}
func (p *gcParser) next() {
p.tok = p.scanner.Scan()
switch p.tok {
case scanner.Ident, scanner.Int, scanner.String:
p.lit = p.scanner.TokenText()
default:
p.lit = ""
}
if trace {
fmt.Printf("%s: %q -> %q\n", scanner.TokenString(p.tok), p.scanner.TokenText(), p.lit)
}
}
func (p *parser) errorExpected(pos scanner.Position, msg string) {
msg = `expected "` + msg + `"`
if pos.Offset == p.pos.Offset {
// the error happened at the current position;
// make the error message more specific
msg += ", found " + scanner.TokenString(p.tok)
if p.tok < 0 {
msg += " " + p.lit
}
}
p.error(pos, msg)
}
// Type =
// BasicType | TypeName | ArrayType | SliceType | StructType |
// PointerType | FuncType | InterfaceType | MapType | ChanType |
// "(" Type ")" .
// BasicType = ident .
// TypeName = ExportedName .
// SliceType = "[" "]" Type .
// PointerType = "*" Type .
// FuncType = "func" Signature .
//
func (p *gcParser) parseType() Type {
switch p.tok {
case scanner.Ident:
switch p.lit {
default:
return p.parseBasicType()
case "struct":
return p.parseStructType()
case "func":
// FuncType
p.next()
return p.parseSignature()
case "interface":
return p.parseInterfaceType()
case "map":
return p.parseMapType()
case "chan":
return p.parseChanType()
}
case '@':
// TypeName
pkg, name := p.parseExportedName()
return p.declare(pkg.Data.(*ast.Scope), ast.Typ, name).Type.(Type)
case '[':
p.next() // look ahead
if p.tok == ']' {
// SliceType
p.next()
return &Slice{Elt: p.parseType()}
}
return p.parseArrayType()
case '*':
// PointerType
p.next()
return &Pointer{Base: p.parseType()}
case '<':
return p.parseChanType()
case '(':
// "(" Type ")"
p.next()
typ := p.parseType()
p.expect(')')
return typ
}
p.errorf("expected type, got %s (%q)", scanner.TokenString(p.tok), p.lit)
return nil
}
// Type =
// BasicType | TypeName | ArrayType | SliceType | StructType |
// PointerType | FuncType | InterfaceType | MapType | ChanType |
// "(" Type ")" .
// BasicType = ident .
// TypeName = ExportedName .
// SliceType = "[" "]" Type .
// PointerType = "*" Type .
//
func (p *gcParser) parseType() Type {
switch p.tok {
case scanner.Ident:
switch p.lit {
default:
return p.parseBasicType()
case "struct":
return p.parseStructType()
case "func":
p.next() // parseFuncType assumes "func" is already consumed
return p.parseFuncType()
case "interface":
return p.parseInterfaceType()
case "map":
return p.parseMapType()
case "chan":
return p.parseChanType()
}
case scanner.String:
// TypeName
return p.parseExportedName(ast.Typ).Type.(Type)
case '[':
p.next() // look ahead
if p.tok == ']' {
// SliceType
p.next()
return &Slice{Elt: p.parseType()}
}
return p.parseArrayType()
case '*':
// PointerType
p.next()
return &Pointer{Base: p.parseType()}
case '<':
return p.parseChanType()
case '(':
// "(" Type ")"
p.next()
typ := p.parseType()
p.expect(')')
return typ
}
p.errorf("expected type, got %s (%q)", scanner.TokenString(p.tok), p.lit)
return nil
}
// Type =
// BasicType | TypeName | ArrayType | SliceType | StructType |
// PointerType | FuncType | InterfaceType | MapType | ChanType |
// "(" Type ")" .
// BasicType = ident .
// TypeName = ExportedName .
// SliceType = "[" "]" Type .
// PointerType = "*" Type .
// FuncType = "func" Signature .
func (p *gcParser) parseType() ast.Expr {
switch p.tok {
case scanner.Ident:
switch p.lit {
case "struct":
return p.parseStrucType()
case "func":
p.next()
return p.parseSignature()
case "interface":
return p.parseInterfaceType()
case "map":
return p.parseMapType()
case "chan":
return p.parseChanType()
default:
lit := p.lit
p.next()
return ast.NewIdent(lit)
}
case '@':
return p.parseExportedName()
case '[':
return p.parseArrayOrSliceType()
case '*':
p.next()
return &ast.StarExpr{X: p.parseType()}
case '<':
return p.parseChanType()
case '(':
p.next()
typ := p.parseType()
p.expect(')')
return typ
}
p.errorf("unexpected token: %s", scanner.TokenString(p.tok))
return nil
}
/*func (d *Decoder) decode(src io.Reader) {
}
*/
func main() {
flag.Parse()
if flag.NArg() != 1 {
fmt.Println("wrong number of arguments")
os.Exit(1)
}
file, err := os.Open(flag.Arg(0), os.O_RDONLY, 0)
if file == nil {
fmt.Printf("can't open file; err=%s\n", err.String())
os.Exit(1)
}
var s scanner.Scanner
s.Init(file)
tok := s.Scan()
for tok != scanner.EOF {
fmt.Println(scanner.TokenString(tok))
tok = s.Scan()
}
fmt.Println()
file.Close()
}