// 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 define(kind ast.ObjKind, name string) *ast.Object {
obj := ast.NewObj(kind, name)
if scope.Insert(obj) != nil {
panic("types internal error: double declaration")
}
return obj
}
// ExportedName = ImportPath "." dotIdentifier .
//
func (p *gcParser) parseExportedName(kind ast.ObjKind) *ast.Object {
pkg := p.parsePkgId()
p.expect('.')
name := p.parseDotIdent()
// a type may have been declared before - if it exists
// already in the respective package scope, return that
// type
scope := pkg.Data.(*ast.Scope)
if kind == ast.Typ {
if obj := scope.Lookup(name); obj != nil {
assert(obj.Kind == ast.Typ)
return obj
}
}
// any other object must be a newly declared object -
// create it and insert it into the package scope
obj := ast.NewObj(kind, name)
if scope.Insert(obj) != nil {
p.errorf("already declared: %s", obj.Name)
}
// a new type object is a named type and may be referred
// to before the underlying type is known - set it up
if kind == ast.Typ {
obj.Type = &Name{Obj: obj}
}
return obj
}
// ImportPath = string_lit .
//
func (p *gcParser) parsePkgId() *ast.Object {
id, err := strconv.Unquote(p.expect(scanner.String))
if err != nil {
p.error(err)
}
switch id {
case "":
// id == "" stands for the imported package id
// (only known at time of package installation)
id = p.id
case "unsafe":
// package unsafe is not in the imports map - handle explicitly
return Unsafe
}
pkg := p.imports[id]
if pkg == nil {
scope = ast.NewScope(nil)
pkg = ast.NewObj(ast.Pkg, "")
pkg.Data = scope
p.imports[id] = pkg
}
return pkg
}
func init() {
scope = ast.NewScope(nil)
Universe = scope
Bool = defType("bool")
defType("byte") // TODO(gri) should be an alias for uint8
defType("complex64")
Complex128 = defType("complex128")
defType("float32")
Float64 = defType("float64")
defType("int8")
defType("int16")
defType("int32")
defType("int64")
String = defType("string")
defType("uint8")
defType("uint16")
defType("uint32")
defType("uint64")
Int = defType("int")
defType("uint")
defType("uintptr")
defConst("true")
defConst("false")
defConst("iota")
defConst("nil")
defFun("append")
defFun("cap")
defFun("close")
defFun("complex")
defFun("copy")
defFun("imag")
defFun("len")
defFun("make")
defFun("new")
defFun("panic")
defFun("print")
defFun("println")
defFun("real")
defFun("recover")
scope = ast.NewScope(nil)
Unsafe = ast.NewObj(ast.Pkg, "unsafe")
Unsafe.Data = scope
defType("Pointer")
defFun("Alignof")
defFun("New")
defFun("NewArray")
defFun("Offsetof")
defFun("Reflect")
defFun("Sizeof")
defFun("Typeof")
defFun("Unreflect")
}
// findField returns the object with the given name if visible in the type's scope.
// If no such object is found, an error is reported and a bad object is returned instead.
func (tc *typechecker) findField(typ *Type, name *ast.Ident) (obj *ast.Object) {
// TODO(gri) This is simplistic at the moment and ignores anonymous fields.
obj = typ.Scope.Lookup(name.Name)
if obj == nil {
tc.Errorf(name.Pos(), "%s not declared", name.Name)
obj = ast.NewObj(ast.Bad, name.Name)
}
return
}
// find returns the object with the given name if visible in the current scope hierarchy.
// If no such object is found, an error is reported and a bad object is returned instead.
func (tc *typechecker) find(name *ast.Ident) (obj *ast.Object) {
for s := tc.topScope; s != nil && obj == nil; s = s.Outer {
obj = s.Lookup(name.Name)
}
if obj == nil {
tc.Errorf(name.Pos(), "%s not declared", name.Name)
obj = ast.NewObj(ast.Bad, name.Name)
}
name.Obj = obj
return
}
// declInScope declares an object of a given kind and name in scope and sets the object's Decl and N fields.
// It returns the newly allocated object. If an object with the same name already exists in scope, an error
// is reported and the object is not inserted.
func (tc *typechecker) declInScope(scope *ast.Scope, kind ast.ObjKind, name *ast.Ident, decl interface{}, n int) *ast.Object {
obj := ast.NewObj(kind, name.Name)
obj.Decl = decl
//obj.N = n
name.Obj = obj
if name.Name != "_" {
if alt := scope.Insert(obj); alt != nil {
tc.Errorf(name.Pos(), "%s already declared at %s", name.Name, tc.fset.Position(alt.Pos()).String())
}
}
return obj
}
// collectFields collects struct fields tok = token.STRUCT), interface methods
// (tok = token.INTERFACE), and function arguments/results (tok = token.FUNC).
func (c *checker) collectFields(tok token.Token, list *ast.FieldList, cycleOk bool) (fields ObjList, tags []string, isVariadic bool) {
if list != nil {
for _, field := range list.List {
ftype := field.Type
if t, ok := ftype.(*ast.Ellipsis); ok {
ftype = t.Elt
isVariadic = true
}
typ := c.makeType(ftype, cycleOk)
tag := ""
if field.Tag != nil {
assert(field.Tag.Kind == token.STRING)
tag, _ = strconv.Unquote(field.Tag.Value)
}
if len(field.Names) > 0 {
// named fields
for _, name := range field.Names {
obj := name.Obj
obj.Type = typ
fields = append(fields, obj)
if tok == token.STRUCT {
tags = append(tags, tag)
}
}
} else {
// anonymous field
switch tok {
case token.STRUCT:
tags = append(tags, tag)
fallthrough
case token.FUNC:
obj := ast.NewObj(ast.Var, "")
obj.Type = typ
fields = append(fields, obj)
case token.INTERFACE:
utyp := Underlying(typ)
if typ, ok := utyp.(*Interface); ok {
// TODO(gri) This is not good enough. Check for double declarations!
fields = append(fields, typ.Methods...)
} else if _, ok := utyp.(*Bad); !ok {
// if utyp is Bad, don't complain (the root cause was reported before)
c.errorf(ftype.Pos(), "interface contains embedded non-interface type")
}
default:
panic("unreachable")
}
}
}
}
return
}
// MethodSpec = identifier Signature .
//
func (p *gcParser) parseMethodSpec() *ast.Object {
if p.tok == scanner.Ident {
p.expect(scanner.Ident)
} else {
// TODO(gri) should this be parseExportedName here?
p.parsePkgId()
p.expect('.')
p.parseDotIdent()
}
p.parseSignature()
// TODO(gri) compute method object
return ast.NewObj(ast.Fun, "_")
}
func init() {
Universe = ast.NewScope(nil)
// basic types
for n, name := range BasicTypes {
typ := NewType(Basic)
typ.N = n
obj := ast.NewObj(ast.Typ, name)
obj.Type = typ
typ.Obj = obj
def(obj)
}
// built-in functions
// TODO(gri) implement this
}
// Field = Name Type [ ":" string_lit ] .
//
func (p *gcParser) parseField() (fld *ast.Object, tag string) {
name := p.parseName()
ftyp := p.parseType()
if name == "" {
// anonymous field - ftyp must be T or *T and T must be a type name
if _, ok := Deref(ftyp).(*Name); !ok {
p.errorf("anonymous field expected")
}
}
if p.tok == ':' {
p.next()
tag = p.expect(scanner.String)
}
fld = ast.NewObj(ast.Var, name)
fld.Type = ftyp
return
}
// Parameter = ( identifier | "?" ) [ "..." ] Type [ ":" string_lit ] .
//
func (p *gcParser) parseParameter() (par *ast.Object, isVariadic bool) {
name := p.parseName()
if name == "" {
name = "_" // cannot access unnamed identifiers
}
if p.tok == '.' {
p.expectSpecial("...")
isVariadic = true
}
ptyp := p.parseType()
// ignore argument tag
if p.tok == ':' {
p.next()
p.expect(scanner.String)
}
par = ast.NewObj(ast.Var, name)
par.Type = ptyp
return
}
// Signature = Parameters [ Result ] .
// Result = Type | Parameters .
//
func (p *gcParser) parseSignature() *Func {
params, isVariadic := p.parseParameters()
// optional result type
var results []*ast.Object
switch p.tok {
case scanner.Ident, scanner.String, '[', '*', '<':
// single, unnamed result
result := ast.NewObj(ast.Var, "_")
result.Type = p.parseType()
results = []*ast.Object{result}
case '(':
// named or multiple result(s)
var variadic bool
results, variadic = p.parseParameters()
if variadic {
p.error("... not permitted on result type")
}
}
return &Func{Params: params, Results: results, IsVariadic: isVariadic}
}