1 // Copyright 2013 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
9 "cmd/compile/internal/syntax"
16 // An Object describes a named language entity such as a package,
17 // constant, type, variable, function (incl. methods), or label.
18 // All objects implement the Object interface.
19 type Object interface {
20 Parent() *Scope // scope in which this object is declared; nil for methods and struct fields
21 Pos() syntax.Pos // position of object identifier in declaration
22 Pkg() *Package // package to which this object belongs; nil for labels and objects in the Universe scope
23 Name() string // package local object name
24 Type() Type // object type
25 Exported() bool // reports whether the name starts with a capital letter
26 Id() string // object name if exported, qualified name if not exported (see func Id)
28 // String returns a human-readable string of the object.
31 // order reflects a package-level object's source order: if object
32 // a is before object b in the source, then a.order() < b.order().
33 // order returns a value > 0 for package-level objects; it returns
34 // 0 for all other objects (including objects in file scopes).
37 // color returns the object's color.
40 // setType sets the type of the object.
43 // setOrder sets the order number of the object. It must be > 0.
46 // setColor sets the object's color. It must not be white.
49 // setParent sets the parent scope of the object.
52 // sameId reports whether obj.Id() and Id(pkg, name) are the same.
53 sameId(pkg *Package, name string) bool
55 // scopePos returns the start position of the scope of this Object
58 // setScopePos sets the start position of the scope for this Object.
59 setScopePos(pos syntax.Pos)
62 func isExported(name string) bool {
63 ch, _ := utf8.DecodeRuneInString(name)
64 return unicode.IsUpper(ch)
67 // Id returns name if it is exported, otherwise it
68 // returns the name qualified with the package path.
69 func Id(pkg *Package, name string) string {
73 // unexported names need the package path for differentiation
74 // (if there's no package, make sure we don't start with '.'
75 // as that may change the order of methods between a setup
76 // inside a package and outside a package - which breaks some
79 // pkg is nil for objects in Universe scope and possibly types
80 // introduced via Eval (see also comment in object.sameId)
81 if pkg != nil && pkg.path != "" {
84 return path + "." + name
87 // An object implements the common parts of an Object.
99 // color encodes the color of an object (see Checker.objDecl for details).
102 // An object may be painted in one of three colors.
103 // Color values other than white or black are considered grey.
107 grey // must be > white and black
110 func (c color) String() string {
121 // colorFor returns the (initial) color for an object depending on
122 // whether its type t is known or not.
123 func colorFor(t Type) color {
130 // Parent returns the scope in which the object is declared.
131 // The result is nil for methods and struct fields.
132 func (obj *object) Parent() *Scope { return obj.parent }
134 // Pos returns the declaration position of the object's identifier.
135 func (obj *object) Pos() syntax.Pos { return obj.pos }
137 // Pkg returns the package to which the object belongs.
138 // The result is nil for labels and objects in the Universe scope.
139 func (obj *object) Pkg() *Package { return obj.pkg }
141 // Name returns the object's (package-local, unqualified) name.
142 func (obj *object) Name() string { return obj.name }
144 // Type returns the object's type.
145 func (obj *object) Type() Type { return obj.typ }
147 // Exported reports whether the object is exported (starts with a capital letter).
148 // It doesn't take into account whether the object is in a local (function) scope
150 func (obj *object) Exported() bool { return isExported(obj.name) }
152 // Id is a wrapper for Id(obj.Pkg(), obj.Name()).
153 func (obj *object) Id() string { return Id(obj.pkg, obj.name) }
155 func (obj *object) String() string { panic("abstract") }
156 func (obj *object) order() uint32 { return obj.order_ }
157 func (obj *object) color() color { return obj.color_ }
158 func (obj *object) scopePos() syntax.Pos { return obj.scopePos_ }
160 func (obj *object) setParent(parent *Scope) { obj.parent = parent }
161 func (obj *object) setType(typ Type) { obj.typ = typ }
162 func (obj *object) setOrder(order uint32) { assert(order > 0); obj.order_ = order }
163 func (obj *object) setColor(color color) { assert(color != white); obj.color_ = color }
164 func (obj *object) setScopePos(pos syntax.Pos) { obj.scopePos_ = pos }
166 func (obj *object) sameId(pkg *Package, name string) bool {
168 // "Two identifiers are different if they are spelled differently,
169 // or if they appear in different packages and are not exported.
170 // Otherwise, they are the same."
171 if name != obj.name {
178 // not exported, so packages must be the same (pkg == nil for
179 // fields in Universe scope; this can only happen for types
180 // introduced via Eval)
181 if pkg == nil || obj.pkg == nil {
182 return pkg == obj.pkg
184 // pkg != nil && obj.pkg != nil
185 return pkg.path == obj.pkg.path
188 // less reports whether object a is ordered before object b.
190 // Objects are ordered nil before non-nil, exported before
191 // non-exported, then by name, and finally (for non-exported
192 // functions) by package path.
193 func (a *object) less(b *object) bool {
198 // Nil before non-nil.
206 // Exported functions before non-exported.
207 ea := isExported(a.name)
208 eb := isExported(b.name)
213 // Order by name and then (for non-exported names) by package.
214 if a.name != b.name {
215 return a.name < b.name
218 return a.pkg.path < b.pkg.path
224 // A PkgName represents an imported Go package.
225 // PkgNames don't have a type.
226 type PkgName struct {
229 used bool // set if the package was used
232 // NewPkgName returns a new PkgName object representing an imported package.
233 // The remaining arguments set the attributes found with all Objects.
234 func NewPkgName(pos syntax.Pos, pkg *Package, name string, imported *Package) *PkgName {
235 return &PkgName{object{nil, pos, pkg, name, Typ[Invalid], 0, black, nopos}, imported, false}
238 // Imported returns the package that was imported.
239 // It is distinct from Pkg(), which is the package containing the import statement.
240 func (obj *PkgName) Imported() *Package { return obj.imported }
242 // A Const represents a declared constant.
248 // NewConst returns a new constant with value val.
249 // The remaining arguments set the attributes found with all Objects.
250 func NewConst(pos syntax.Pos, pkg *Package, name string, typ Type, val constant.Value) *Const {
251 return &Const{object{nil, pos, pkg, name, typ, 0, colorFor(typ), nopos}, val}
254 // Val returns the constant's value.
255 func (obj *Const) Val() constant.Value { return obj.val }
257 func (*Const) isDependency() {} // a constant may be a dependency of an initialization expression
259 // A TypeName represents a name for a (defined or alias) type.
260 type TypeName struct {
264 // NewTypeName returns a new type name denoting the given typ.
265 // The remaining arguments set the attributes found with all Objects.
267 // The typ argument may be a defined (Named) type or an alias type.
268 // It may also be nil such that the returned TypeName can be used as
269 // argument for NewNamed, which will set the TypeName's type as a side-
271 func NewTypeName(pos syntax.Pos, pkg *Package, name string, typ Type) *TypeName {
272 return &TypeName{object{nil, pos, pkg, name, typ, 0, colorFor(typ), nopos}}
275 // NewTypeNameLazy returns a new defined type like NewTypeName, but it
276 // lazily calls resolve to finish constructing the Named object.
277 func NewTypeNameLazy(pos syntax.Pos, pkg *Package, name string, load func(named *Named) (tparams []*TypeParam, underlying Type, methods []*Func)) *TypeName {
278 obj := NewTypeName(pos, pkg, name, nil)
279 NewNamed(obj, nil, nil).loader = load
283 // IsAlias reports whether obj is an alias name for a type.
284 func (obj *TypeName) IsAlias() bool {
285 switch t := obj.typ.(type) {
289 // unsafe.Pointer is not an alias.
290 if obj.pkg == Unsafe {
293 // Any user-defined type name for a basic type is an alias for a
294 // basic type (because basic types are pre-declared in the Universe
295 // scope, outside any package scope), and so is any type name with
296 // a different name than the name of the basic type it refers to.
297 // Additionally, we need to look for "byte" and "rune" because they
298 // are aliases but have the same names (for better error messages).
299 return obj.pkg != nil || t.name != obj.name || t == universeByte || t == universeRune
309 // A Variable represents a declared variable (including function parameters and results, and struct fields).
312 embedded bool // if set, the variable is an embedded struct field, and name is the type name
313 isField bool // var is struct field
314 used bool // set if the variable was used
315 origin *Var // if non-nil, the Var from which this one was instantiated
318 // NewVar returns a new variable.
319 // The arguments set the attributes found with all Objects.
320 func NewVar(pos syntax.Pos, pkg *Package, name string, typ Type) *Var {
321 return &Var{object: object{nil, pos, pkg, name, typ, 0, colorFor(typ), nopos}}
324 // NewParam returns a new variable representing a function parameter.
325 func NewParam(pos syntax.Pos, pkg *Package, name string, typ Type) *Var {
326 return &Var{object: object{nil, pos, pkg, name, typ, 0, colorFor(typ), nopos}, used: true} // parameters are always 'used'
329 // NewField returns a new variable representing a struct field.
330 // For embedded fields, the name is the unqualified type name
331 // under which the field is accessible.
332 func NewField(pos syntax.Pos, pkg *Package, name string, typ Type, embedded bool) *Var {
333 return &Var{object: object{nil, pos, pkg, name, typ, 0, colorFor(typ), nopos}, embedded: embedded, isField: true}
336 // Anonymous reports whether the variable is an embedded field.
337 // Same as Embedded; only present for backward-compatibility.
338 func (obj *Var) Anonymous() bool { return obj.embedded }
340 // Embedded reports whether the variable is an embedded field.
341 func (obj *Var) Embedded() bool { return obj.embedded }
343 // IsField reports whether the variable is a struct field.
344 func (obj *Var) IsField() bool { return obj.isField }
346 // Origin returns the canonical Var for its receiver, i.e. the Var object
347 // recorded in Info.Defs.
349 // For synthetic Vars created during instantiation (such as struct fields or
350 // function parameters that depend on type arguments), this will be the
351 // corresponding Var on the generic (uninstantiated) type. For all other Vars
352 // Origin returns the receiver.
353 func (obj *Var) Origin() *Var {
354 if obj.origin != nil {
360 func (*Var) isDependency() {} // a variable may be a dependency of an initialization expression
362 // A Func represents a declared function, concrete method, or abstract
363 // (interface) method. Its Type() is always a *Signature.
364 // An abstract method may belong to many interfaces due to embedding.
367 hasPtrRecv_ bool // only valid for methods that don't have a type yet; use hasPtrRecv() to read
368 origin *Func // if non-nil, the Func from which this one was instantiated
371 // NewFunc returns a new function with the given signature, representing
372 // the function's type.
373 func NewFunc(pos syntax.Pos, pkg *Package, name string, sig *Signature) *Func {
374 // don't store a (typed) nil signature
379 return &Func{object{nil, pos, pkg, name, typ, 0, colorFor(typ), nopos}, false, nil}
382 // FullName returns the package- or receiver-type-qualified name of
383 // function or method obj.
384 func (obj *Func) FullName() string {
386 writeFuncName(&buf, obj, nil)
390 // Scope returns the scope of the function's body block.
391 // The result is nil for imported or instantiated functions and methods
392 // (but there is also no mechanism to get to an instantiated function).
393 func (obj *Func) Scope() *Scope { return obj.typ.(*Signature).scope }
395 // Origin returns the canonical Func for its receiver, i.e. the Func object
396 // recorded in Info.Defs.
398 // For synthetic functions created during instantiation (such as methods on an
399 // instantiated Named type or interface methods that depend on type arguments),
400 // this will be the corresponding Func on the generic (uninstantiated) type.
401 // For all other Funcs Origin returns the receiver.
402 func (obj *Func) Origin() *Func {
403 if obj.origin != nil {
409 // Pkg returns the package to which the function belongs.
411 // The result is nil for methods of types in the Universe scope,
412 // like method Error of the error built-in interface type.
413 func (obj *Func) Pkg() *Package { return obj.object.Pkg() }
415 // hasPtrRecv reports whether the receiver is of the form *T for the given method obj.
416 func (obj *Func) hasPtrRecv() bool {
417 // If a method's receiver type is set, use that as the source of truth for the receiver.
418 // Caution: Checker.funcDecl (decl.go) marks a function by setting its type to an empty
419 // signature. We may reach here before the signature is fully set up: we must explicitly
420 // check if the receiver is set (we cannot just look for non-nil obj.typ).
421 if sig, _ := obj.typ.(*Signature); sig != nil && sig.recv != nil {
422 _, isPtr := deref(sig.recv.typ)
426 // If a method's type is not set it may be a method/function that is:
427 // 1) client-supplied (via NewFunc with no signature), or
428 // 2) internally created but not yet type-checked.
429 // For case 1) we can't do anything; the client must know what they are doing.
430 // For case 2) we can use the information gathered by the resolver.
431 return obj.hasPtrRecv_
434 func (*Func) isDependency() {} // a function may be a dependency of an initialization expression
436 // A Label represents a declared label.
437 // Labels don't have a type.
440 used bool // set if the label was used
443 // NewLabel returns a new label.
444 func NewLabel(pos syntax.Pos, pkg *Package, name string) *Label {
445 return &Label{object{pos: pos, pkg: pkg, name: name, typ: Typ[Invalid], color_: black}, false}
448 // A Builtin represents a built-in function.
449 // Builtins don't have a valid type.
450 type Builtin struct {
455 func newBuiltin(id builtinId) *Builtin {
456 return &Builtin{object{name: predeclaredFuncs[id].name, typ: Typ[Invalid], color_: black}, id}
459 // Nil represents the predeclared value nil.
464 func writeObject(buf *bytes.Buffer, obj Object, qf Qualifier) {
468 switch obj := obj.(type) {
470 fmt.Fprintf(buf, "package %s", obj.Name())
471 if path := obj.imported.path; path != "" && path != obj.name {
472 fmt.Fprintf(buf, " (%q)", path)
477 buf.WriteString("const")
481 buf.WriteString("type")
482 if isTypeParam(typ) {
483 buf.WriteString(" parameter")
488 buf.WriteString("field")
490 buf.WriteString("var")
494 buf.WriteString("func ")
495 writeFuncName(buf, obj, qf)
497 WriteSignature(buf, typ.(*Signature), qf)
502 buf.WriteString("label")
506 buf.WriteString("builtin")
510 buf.WriteString("nil")
514 panic(fmt.Sprintf("writeObject(%T)", obj))
519 // For package-level objects, qualify the name.
520 if obj.Pkg() != nil && obj.Pkg().scope.Lookup(obj.Name()) == obj {
521 buf.WriteString(packagePrefix(obj.Pkg(), qf))
523 buf.WriteString(obj.Name())
530 switch t := typ.(type) {
532 // Don't print anything more for basic types since there's
533 // no more information.
536 if t.TypeParams().Len() > 0 {
537 newTypeWriter(buf, qf).tParamList(t.TypeParams().list())
541 buf.WriteString(" =")
542 } else if t, _ := typ.(*TypeParam); t != nil {
545 // TODO(gri) should this be fromRHS for *Named?
550 // Special handling for any: because WriteType will format 'any' as 'any',
551 // resulting in the object string `type any = any` rather than `type any =
552 // interface{}`. To avoid this, swap in a different empty interface.
553 if obj == universeAny {
554 assert(Identical(typ, &emptyInterface))
555 typ = &emptyInterface
559 WriteType(buf, typ, qf)
562 func packagePrefix(pkg *Package, qf Qualifier) string {
578 // ObjectString returns the string form of obj.
579 // The Qualifier controls the printing of
580 // package-level objects, and may be nil.
581 func ObjectString(obj Object, qf Qualifier) string {
583 writeObject(&buf, obj, qf)
587 func (obj *PkgName) String() string { return ObjectString(obj, nil) }
588 func (obj *Const) String() string { return ObjectString(obj, nil) }
589 func (obj *TypeName) String() string { return ObjectString(obj, nil) }
590 func (obj *Var) String() string { return ObjectString(obj, nil) }
591 func (obj *Func) String() string { return ObjectString(obj, nil) }
592 func (obj *Label) String() string { return ObjectString(obj, nil) }
593 func (obj *Builtin) String() string { return ObjectString(obj, nil) }
594 func (obj *Nil) String() string { return ObjectString(obj, nil) }
596 func writeFuncName(buf *bytes.Buffer, f *Func, qf Qualifier) {
598 sig := f.typ.(*Signature)
599 if recv := sig.Recv(); recv != nil {
601 if _, ok := recv.Type().(*Interface); ok {
602 // gcimporter creates abstract methods of
603 // named interfaces using the interface type
604 // (not the named type) as the receiver.
605 // Don't print it in full.
606 buf.WriteString("interface")
608 WriteType(buf, recv.Type(), qf)
612 } else if f.pkg != nil {
613 buf.WriteString(packagePrefix(f.pkg, qf))
616 buf.WriteString(f.name)