| // Copyright 2013 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package types |
| |
| import ( |
| "bytes" |
| "fmt" |
| "go/constant" |
| "go/token" |
| ) |
| |
| // An Object describes a named language entity such as a package, |
| // constant, type, variable, function (incl. methods), or label. |
| // All objects implement the Object interface. |
| // |
| type Object interface { |
| Parent() *Scope // scope in which this object is declared; nil for methods and struct fields |
| Pos() token.Pos // position of object identifier in declaration |
| Pkg() *Package // package to which this object belongs; nil for labels and objects in the Universe scope |
| Name() string // package local object name |
| Type() Type // object type |
| Exported() bool // reports whether the name starts with a capital letter |
| Id() string // object name if exported, qualified name if not exported (see func Id) |
| |
| // String returns a human-readable string of the object. |
| String() string |
| |
| // order reflects a package-level object's source order: if object |
| // a is before object b in the source, then a.order() < b.order(). |
| // order returns a value > 0 for package-level objects; it returns |
| // 0 for all other objects (including objects in file scopes). |
| order() uint32 |
| |
| // color returns the object's color. |
| color() color |
| |
| // setType sets the type of the object. |
| setType(Type) |
| |
| // setOrder sets the order number of the object. It must be > 0. |
| setOrder(uint32) |
| |
| // setColor sets the object's color. It must not be white. |
| setColor(color color) |
| |
| // setParent sets the parent scope of the object. |
| setParent(*Scope) |
| |
| // sameId reports whether obj.Id() and Id(pkg, name) are the same. |
| sameId(pkg *Package, name string) bool |
| |
| // scopePos returns the start position of the scope of this Object |
| scopePos() token.Pos |
| |
| // setScopePos sets the start position of the scope for this Object. |
| setScopePos(pos token.Pos) |
| } |
| |
| // Id returns name if it is exported, otherwise it |
| // returns the name qualified with the package path. |
| func Id(pkg *Package, name string) string { |
| if token.IsExported(name) { |
| return name |
| } |
| // unexported names need the package path for differentiation |
| // (if there's no package, make sure we don't start with '.' |
| // as that may change the order of methods between a setup |
| // inside a package and outside a package - which breaks some |
| // tests) |
| path := "_" |
| // pkg is nil for objects in Universe scope and possibly types |
| // introduced via Eval (see also comment in object.sameId) |
| if pkg != nil && pkg.path != "" { |
| path = pkg.path |
| } |
| return path + "." + name |
| } |
| |
| // An object implements the common parts of an Object. |
| type object struct { |
| parent *Scope |
| pos token.Pos |
| pkg *Package |
| name string |
| typ Type |
| order_ uint32 |
| color_ color |
| scopePos_ token.Pos |
| } |
| |
| // color encodes the color of an object (see Checker.objDecl for details). |
| type color uint32 |
| |
| // An object may be painted in one of three colors. |
| // Color values other than white or black are considered grey. |
| const ( |
| white color = iota |
| black |
| grey // must be > white and black |
| ) |
| |
| func (c color) String() string { |
| switch c { |
| case white: |
| return "white" |
| case black: |
| return "black" |
| default: |
| return "grey" |
| } |
| } |
| |
| // colorFor returns the (initial) color for an object depending on |
| // whether its type t is known or not. |
| func colorFor(t Type) color { |
| if t != nil { |
| return black |
| } |
| return white |
| } |
| |
| // Parent returns the scope in which the object is declared. |
| // The result is nil for methods and struct fields. |
| func (obj *object) Parent() *Scope { return obj.parent } |
| |
| // Pos returns the declaration position of the object's identifier. |
| func (obj *object) Pos() token.Pos { return obj.pos } |
| |
| // Pkg returns the package to which the object belongs. |
| // The result is nil for labels and objects in the Universe scope. |
| func (obj *object) Pkg() *Package { return obj.pkg } |
| |
| // Name returns the object's (package-local, unqualified) name. |
| func (obj *object) Name() string { return obj.name } |
| |
| // Type returns the object's type. |
| func (obj *object) Type() Type { return obj.typ } |
| |
| // Exported reports whether the object is exported (starts with a capital letter). |
| // It doesn't take into account whether the object is in a local (function) scope |
| // or not. |
| func (obj *object) Exported() bool { return token.IsExported(obj.name) } |
| |
| // Id is a wrapper for Id(obj.Pkg(), obj.Name()). |
| func (obj *object) Id() string { return Id(obj.pkg, obj.name) } |
| |
| func (obj *object) String() string { panic("abstract") } |
| func (obj *object) order() uint32 { return obj.order_ } |
| func (obj *object) color() color { return obj.color_ } |
| func (obj *object) scopePos() token.Pos { return obj.scopePos_ } |
| |
| func (obj *object) setParent(parent *Scope) { obj.parent = parent } |
| func (obj *object) setType(typ Type) { obj.typ = typ } |
| func (obj *object) setOrder(order uint32) { assert(order > 0); obj.order_ = order } |
| func (obj *object) setColor(color color) { assert(color != white); obj.color_ = color } |
| func (obj *object) setScopePos(pos token.Pos) { obj.scopePos_ = pos } |
| |
| func (obj *object) sameId(pkg *Package, name string) bool { |
| // spec: |
| // "Two identifiers are different if they are spelled differently, |
| // or if they appear in different packages and are not exported. |
| // Otherwise, they are the same." |
| if name != obj.name { |
| return false |
| } |
| // obj.Name == name |
| if obj.Exported() { |
| return true |
| } |
| // not exported, so packages must be the same (pkg == nil for |
| // fields in Universe scope; this can only happen for types |
| // introduced via Eval) |
| if pkg == nil || obj.pkg == nil { |
| return pkg == obj.pkg |
| } |
| // pkg != nil && obj.pkg != nil |
| return pkg.path == obj.pkg.path |
| } |
| |
| // A PkgName represents an imported Go package. |
| // PkgNames don't have a type. |
| type PkgName struct { |
| object |
| imported *Package |
| used bool // set if the package was used |
| } |
| |
| // NewPkgName returns a new PkgName object representing an imported package. |
| // The remaining arguments set the attributes found with all Objects. |
| func NewPkgName(pos token.Pos, pkg *Package, name string, imported *Package) *PkgName { |
| return &PkgName{object{nil, pos, pkg, name, Typ[Invalid], 0, black, token.NoPos}, imported, false} |
| } |
| |
| // Imported returns the package that was imported. |
| // It is distinct from Pkg(), which is the package containing the import statement. |
| func (obj *PkgName) Imported() *Package { return obj.imported } |
| |
| // A Const represents a declared constant. |
| type Const struct { |
| object |
| val constant.Value |
| } |
| |
| // NewConst returns a new constant with value val. |
| // The remaining arguments set the attributes found with all Objects. |
| func NewConst(pos token.Pos, pkg *Package, name string, typ Type, val constant.Value) *Const { |
| return &Const{object{nil, pos, pkg, name, typ, 0, colorFor(typ), token.NoPos}, val} |
| } |
| |
| // Val returns the constant's value. |
| func (obj *Const) Val() constant.Value { return obj.val } |
| |
| func (*Const) isDependency() {} // a constant may be a dependency of an initialization expression |
| |
| // A TypeName represents a name for a (defined or alias) type. |
| type TypeName struct { |
| object |
| } |
| |
| // NewTypeName returns a new type name denoting the given typ. |
| // The remaining arguments set the attributes found with all Objects. |
| // |
| // The typ argument may be a defined (Named) type or an alias type. |
| // It may also be nil such that the returned TypeName can be used as |
| // argument for NewNamed, which will set the TypeName's type as a side- |
| // effect. |
| func NewTypeName(pos token.Pos, pkg *Package, name string, typ Type) *TypeName { |
| return &TypeName{object{nil, pos, pkg, name, typ, 0, colorFor(typ), token.NoPos}} |
| } |
| |
| // IsAlias reports whether obj is an alias name for a type. |
| func (obj *TypeName) IsAlias() bool { |
| switch t := obj.typ.(type) { |
| case nil: |
| return false |
| case *Basic: |
| // unsafe.Pointer is not an alias. |
| if obj.pkg == Unsafe { |
| return false |
| } |
| // Any user-defined type name for a basic type is an alias for a |
| // basic type (because basic types are pre-declared in the Universe |
| // scope, outside any package scope), and so is any type name with |
| // a different name than the name of the basic type it refers to. |
| // Additionally, we need to look for "byte" and "rune" because they |
| // are aliases but have the same names (for better error messages). |
| return obj.pkg != nil || t.name != obj.name || t == universeByte || t == universeRune |
| case *Named: |
| return obj != t.obj |
| default: |
| return true |
| } |
| } |
| |
| // A Variable represents a declared variable (including function parameters and results, and struct fields). |
| type Var struct { |
| object |
| embedded bool // if set, the variable is an embedded struct field, and name is the type name |
| isField bool // var is struct field |
| used bool // set if the variable was used |
| } |
| |
| // NewVar returns a new variable. |
| // The arguments set the attributes found with all Objects. |
| func NewVar(pos token.Pos, pkg *Package, name string, typ Type) *Var { |
| return &Var{object: object{nil, pos, pkg, name, typ, 0, colorFor(typ), token.NoPos}} |
| } |
| |
| // NewParam returns a new variable representing a function parameter. |
| func NewParam(pos token.Pos, pkg *Package, name string, typ Type) *Var { |
| return &Var{object: object{nil, pos, pkg, name, typ, 0, colorFor(typ), token.NoPos}, used: true} // parameters are always 'used' |
| } |
| |
| // NewField returns a new variable representing a struct field. |
| // For embedded fields, the name is the unqualified type name |
| /// under which the field is accessible. |
| func NewField(pos token.Pos, pkg *Package, name string, typ Type, embedded bool) *Var { |
| return &Var{object: object{nil, pos, pkg, name, typ, 0, colorFor(typ), token.NoPos}, embedded: embedded, isField: true} |
| } |
| |
| // Anonymous reports whether the variable is an embedded field. |
| // Same as Embedded; only present for backward-compatibility. |
| func (obj *Var) Anonymous() bool { return obj.embedded } |
| |
| // Embedded reports whether the variable is an embedded field. |
| func (obj *Var) Embedded() bool { return obj.embedded } |
| |
| // IsField reports whether the variable is a struct field. |
| func (obj *Var) IsField() bool { return obj.isField } |
| |
| func (*Var) isDependency() {} // a variable may be a dependency of an initialization expression |
| |
| // A Func represents a declared function, concrete method, or abstract |
| // (interface) method. Its Type() is always a *Signature. |
| // An abstract method may belong to many interfaces due to embedding. |
| type Func struct { |
| object |
| hasPtrRecv bool // only valid for methods that don't have a type yet |
| } |
| |
| // NewFunc returns a new function with the given signature, representing |
| // the function's type. |
| func NewFunc(pos token.Pos, pkg *Package, name string, sig *Signature) *Func { |
| // don't store a (typed) nil signature |
| var typ Type |
| if sig != nil { |
| typ = sig |
| } |
| return &Func{object{nil, pos, pkg, name, typ, 0, colorFor(typ), token.NoPos}, false} |
| } |
| |
| // FullName returns the package- or receiver-type-qualified name of |
| // function or method obj. |
| func (obj *Func) FullName() string { |
| var buf bytes.Buffer |
| writeFuncName(&buf, obj, nil) |
| return buf.String() |
| } |
| |
| // Scope returns the scope of the function's body block. |
| func (obj *Func) Scope() *Scope { return obj.typ.(*Signature).scope } |
| |
| func (*Func) isDependency() {} // a function may be a dependency of an initialization expression |
| |
| // A Label represents a declared label. |
| // Labels don't have a type. |
| type Label struct { |
| object |
| used bool // set if the label was used |
| } |
| |
| // NewLabel returns a new label. |
| func NewLabel(pos token.Pos, pkg *Package, name string) *Label { |
| return &Label{object{pos: pos, pkg: pkg, name: name, typ: Typ[Invalid], color_: black}, false} |
| } |
| |
| // A Builtin represents a built-in function. |
| // Builtins don't have a valid type. |
| type Builtin struct { |
| object |
| id builtinId |
| } |
| |
| func newBuiltin(id builtinId) *Builtin { |
| return &Builtin{object{name: predeclaredFuncs[id].name, typ: Typ[Invalid], color_: black}, id} |
| } |
| |
| // Nil represents the predeclared value nil. |
| type Nil struct { |
| object |
| } |
| |
| func writeObject(buf *bytes.Buffer, obj Object, qf Qualifier) { |
| var tname *TypeName |
| typ := obj.Type() |
| |
| switch obj := obj.(type) { |
| case *PkgName: |
| fmt.Fprintf(buf, "package %s", obj.Name()) |
| if path := obj.imported.path; path != "" && path != obj.name { |
| fmt.Fprintf(buf, " (%q)", path) |
| } |
| return |
| |
| case *Const: |
| buf.WriteString("const") |
| |
| case *TypeName: |
| tname = obj |
| buf.WriteString("type") |
| |
| case *Var: |
| if obj.isField { |
| buf.WriteString("field") |
| } else { |
| buf.WriteString("var") |
| } |
| |
| case *Func: |
| buf.WriteString("func ") |
| writeFuncName(buf, obj, qf) |
| if typ != nil { |
| WriteSignature(buf, typ.(*Signature), qf) |
| } |
| return |
| |
| case *Label: |
| buf.WriteString("label") |
| typ = nil |
| |
| case *Builtin: |
| buf.WriteString("builtin") |
| typ = nil |
| |
| case *Nil: |
| buf.WriteString("nil") |
| return |
| |
| default: |
| panic(fmt.Sprintf("writeObject(%T)", obj)) |
| } |
| |
| buf.WriteByte(' ') |
| |
| // For package-level objects, qualify the name. |
| if obj.Pkg() != nil && obj.Pkg().scope.Lookup(obj.Name()) == obj { |
| writePackage(buf, obj.Pkg(), qf) |
| } |
| buf.WriteString(obj.Name()) |
| |
| if typ == nil { |
| return |
| } |
| |
| if tname != nil { |
| // We have a type object: Don't print anything more for |
| // basic types since there's no more information (names |
| // are the same; see also comment in TypeName.IsAlias). |
| if _, ok := typ.(*Basic); ok { |
| return |
| } |
| if tname.IsAlias() { |
| buf.WriteString(" =") |
| } else { |
| typ = under(typ) |
| } |
| } |
| |
| buf.WriteByte(' ') |
| WriteType(buf, typ, qf) |
| } |
| |
| func writePackage(buf *bytes.Buffer, pkg *Package, qf Qualifier) { |
| if pkg == nil { |
| return |
| } |
| var s string |
| if qf != nil { |
| s = qf(pkg) |
| } else { |
| s = pkg.Path() |
| } |
| if s != "" { |
| buf.WriteString(s) |
| buf.WriteByte('.') |
| } |
| } |
| |
| // ObjectString returns the string form of obj. |
| // The Qualifier controls the printing of |
| // package-level objects, and may be nil. |
| func ObjectString(obj Object, qf Qualifier) string { |
| var buf bytes.Buffer |
| writeObject(&buf, obj, qf) |
| return buf.String() |
| } |
| |
| func (obj *PkgName) String() string { return ObjectString(obj, nil) } |
| func (obj *Const) String() string { return ObjectString(obj, nil) } |
| func (obj *TypeName) String() string { return ObjectString(obj, nil) } |
| func (obj *Var) String() string { return ObjectString(obj, nil) } |
| func (obj *Func) String() string { return ObjectString(obj, nil) } |
| func (obj *Label) String() string { return ObjectString(obj, nil) } |
| func (obj *Builtin) String() string { return ObjectString(obj, nil) } |
| func (obj *Nil) String() string { return ObjectString(obj, nil) } |
| |
| func writeFuncName(buf *bytes.Buffer, f *Func, qf Qualifier) { |
| if f.typ != nil { |
| sig := f.typ.(*Signature) |
| if recv := sig.Recv(); recv != nil { |
| buf.WriteByte('(') |
| if _, ok := recv.Type().(*Interface); ok { |
| // gcimporter creates abstract methods of |
| // named interfaces using the interface type |
| // (not the named type) as the receiver. |
| // Don't print it in full. |
| buf.WriteString("interface") |
| } else { |
| WriteType(buf, recv.Type(), qf) |
| } |
| buf.WriteByte(')') |
| buf.WriteByte('.') |
| } else if f.pkg != nil { |
| writePackage(buf, f.pkg, qf) |
| } |
| } |
| buf.WriteString(f.name) |
| } |