Golang Object.Pos方法代码示例

func (tc *typechecker) resolve(obj *ast.Object) {
	// check for declaration cycles
	if tc.cyclemap[obj] {
		tc.Errorf(obj.Pos(), "illegal cycle in declaration of %s", obj.Name)
		obj.Kind = ast.Bad
		return
	}
	tc.cyclemap[obj] = true
	defer func() {
		tc.cyclemap[obj] = false, false
	}()

	// resolve non-type objects
	typ, _ := obj.Type.(*Type)
	if typ == nil {
		switch obj.Kind {
		case ast.Bad:
			// ignore

		case ast.Con:
			tc.declConst(obj)

		case ast.Var:
			tc.declVar(obj)
			obj.Type = tc.typeFor(nil, obj.Decl.(*ast.ValueSpec).Type, false)

		case ast.Fun:
			obj.Type = NewType(Function)
			t := obj.Decl.(*ast.FuncDecl).Type
			tc.declSignature(obj.Type.(*Type), nil, t.Params, t.Results)

		default:
			// type objects have non-nil types when resolve is called
			if debug {
				fmt.Printf("kind = %s\n", obj.Kind)
			}
			panic("unreachable")
		}
		return
	}

	// resolve type objects
	if typ.Form == Unresolved {
		tc.typeFor(typ, typ.Obj.Decl.(*ast.TypeSpec).Type, false)

		// provide types for all methods
		for _, obj := range typ.Scope.Objects {
			if obj.Kind == ast.Fun {
				assert(obj.Type == nil)
				obj.Type = NewType(Method)
				f := obj.Decl.(*ast.FuncDecl)
				t := f.Type
				tc.declSignature(obj.Type.(*Type), f.Recv, t.Params, t.Results)
			}
		}
	}
}

func objDoc(fset *token.FileSet, pkg *ast.Package, tabIndent bool, tabWidth int, obj *ast.Object) *Doc {
	decl := obj.Decl
	kind := obj.Kind.String()
	tp := fset.Position(obj.Pos())
	objSrc := ""
	pkgName := ""
	if pkg != nil && pkg.Name != "builtin" {
		pkgName = pkg.Name
	}

	if obj.Kind == ast.Pkg {
		pkgName = ""
		doc := ""
		// special-case `package name` is generated as a TypeSpec
		if v, ok := obj.Decl.(*ast.TypeSpec); ok && v.Doc != nil {
			doc = "/*\n" + v.Doc.Text() + "\n*/\n"
		}
		objSrc = doc + "package " + obj.Name
	} else if af, ok := pkg.Files[tp.Filename]; ok {
		switch decl.(type) {
		case *ast.TypeSpec, *ast.ValueSpec, *ast.Field:
			line := tp.Line - 1
			for _, cg := range af.Comments {
				cgp := fset.Position(cg.End())
				if cgp.Filename == tp.Filename && cgp.Line == line {
					switch v := decl.(type) {
					case *ast.TypeSpec:
						v.Doc = cg
					case *ast.ValueSpec:
						v.Doc = cg
					case *ast.Field:
						pkgName = ""
						kind = "field"
					}
					break
				}
			}
		}
	}

	if objSrc == "" {
		objSrc, _ = printSrc(fset, decl, tabIndent, tabWidth)
	}

	return &Doc{
		Src:  objSrc,
		Pkg:  pkgName,
		Name: obj.Name,
		Kind: kind,
		Fn:   tp.Filename,
		Row:  tp.Line - 1,
		Col:  tp.Column - 1,
	}
}

// object typechecks an object by assigning it a type; obj.Type must be nil.
// Callers must check obj.Type before calling object; this eliminates a call
// for each identifier that has been typechecked already, a common scenario.
//
func (check *checker) object(obj *ast.Object, cycleOk bool) {
	assert(obj.Type == nil)

	switch obj.Kind {
	case ast.Bad, ast.Pkg:
		// nothing to do

	case ast.Con, ast.Var:
		// The obj.Data field for constants and variables is initialized
		// to the respective (hypothetical, for variables) iota value by
		// the parser. The object's fields can be in one of the following
		// states:
		// Type != nil  =>  the constant value is Data
		// Type == nil  =>  the object is not typechecked yet, and Data can be:
		// Data is int  =>  Data is the value of iota for this declaration
		// Data == nil  =>  the object's expression is being evaluated
		if obj.Data == nil {
			check.errorf(obj.Pos(), "illegal cycle in initialization of %s", obj.Name)
			obj.Type = Typ[Invalid]
			return
		}
		spec := obj.Decl.(*ast.ValueSpec)
		iota := obj.Data.(int)
		obj.Data = nil
		// determine initialization expressions
		values := spec.Values
		if len(values) == 0 && obj.Kind == ast.Con {
			values = check.initexprs[spec]
		}
		check.valueSpec(spec.Pos(), obj, spec.Names, spec.Type, values, iota)

	case ast.Typ:
		typ := &NamedType{Obj: obj}
		obj.Type = typ // "mark" object so recursion terminates
		typ.Underlying = underlying(check.typ(obj.Decl.(*ast.TypeSpec).Type, cycleOk))
		// typecheck associated method signatures
		if obj.Data != nil {
			scope := obj.Data.(*ast.Scope)
			switch t := typ.Underlying.(type) {
			case *Struct:
				// struct fields must not conflict with methods
				for _, f := range t.Fields {
					if m := scope.Lookup(f.Name); m != nil {
						check.errorf(m.Pos(), "type %s has both field and method named %s", obj.Name, f.Name)
						// ok to continue
					}
				}
			case *Interface:
				// methods cannot be associated with an interface type
				for _, m := range scope.Objects {
					recv := m.Decl.(*ast.FuncDecl).Recv.List[0].Type
					check.errorf(recv.Pos(), "invalid receiver type %s (%s is an interface type)", obj.Name, obj.Name)
					// ok to continue
				}
			}
			// typecheck method signatures
			for _, obj := range scope.Objects {
				mdecl := obj.Decl.(*ast.FuncDecl)
				sig := check.typ(mdecl.Type, cycleOk).(*Signature)
				params, _ := check.collectParams(mdecl.Recv, false)
				sig.Recv = params[0] // the parser/assocMethod ensure there is exactly one parameter
				obj.Type = sig
				check.later(obj, sig, mdecl.Body)
			}
		}

	case ast.Fun:
		fdecl := obj.Decl.(*ast.FuncDecl)
		// methods are typechecked when their receivers are typechecked
		if fdecl.Recv == nil {
			sig := check.typ(fdecl.Type, cycleOk).(*Signature)
			if obj.Name == "init" && (len(sig.Params) != 0 || len(sig.Results) != 0) {
				check.errorf(fdecl.Pos(), "func init must have no arguments and no return values")
				// ok to continue
			}
			obj.Type = sig
			check.later(obj, sig, fdecl.Body)
		}

	default:
		panic("unreachable")
	}
}

// object typechecks an object by assigning it a type; obj.Type must be nil.
// Callers must check obj.Type before calling object; this eliminates a call
// for each identifier that has been typechecked already, a common scenario.
//
func (check *checker) object(obj *ast.Object, cycleOk bool) {
	assert(obj.Type == nil)

	switch obj.Kind {
	case ast.Bad, ast.Pkg:
		// nothing to do

	case ast.Con, ast.Var:
		// The obj.Data field for constants and variables is initialized
		// to the respective (hypothetical, for variables) iota value by
		// the parser. The object's fields can be in one of the following
		// states:
		// Type != nil  =>  the constant value is Data
		// Type == nil  =>  the object is not typechecked yet, and Data can be:
		// Data is int  =>  Data is the value of iota for this declaration
		// Data == nil  =>  the object's expression is being evaluated
		if obj.Data == nil {
			check.errorf(obj.Pos(), "illegal cycle in initialization of %s", obj.Name)
			obj.Type = Typ[Invalid]
			return
		}
		spec := obj.Decl.(*ast.ValueSpec)
		iota := obj.Data.(int)
		obj.Data = nil
		// determine initialization expressions
		values := spec.Values
		if len(values) == 0 && obj.Kind == ast.Con {
			values = check.initexprs[spec]
		}
		check.valueSpec(spec.Pos(), obj, spec.Names, spec.Type, values, iota)

	case ast.Typ:
		typ := &NamedType{Obj: obj}
		obj.Type = typ // "mark" object so recursion terminates
		typ.Underlying = underlying(check.typ(obj.Decl.(*ast.TypeSpec).Type, cycleOk))
		// typecheck associated method signatures
		if obj.Data != nil {
			scope := obj.Data.(*ast.Scope)
			switch t := typ.Underlying.(type) {
			case *Struct:
				// struct fields must not conflict with methods
				for _, f := range t.Fields {
					if m := scope.Lookup(f.Name); m != nil {
						check.errorf(m.Pos(), "type %s has both field and method named %s", obj.Name, f.Name)
					}
				}
				// ok to continue
			case *Interface:
				// methods cannot be associated with an interface type
				for _, m := range scope.Objects {
					recv := m.Decl.(*ast.FuncDecl).Recv.List[0].Type
					check.errorf(recv.Pos(), "invalid receiver type %s (%s is an interface type)", obj.Name, obj.Name)
				}
				// ok to continue
			}
			// typecheck method signatures
			for _, m := range scope.Objects {
				mdecl := m.Decl.(*ast.FuncDecl)
				// TODO(gri) At the moment, the receiver is type-checked when checking
				// the method body. Also, we don't properly track if the receiver is
				// a pointer (i.e., currently, method sets are too large). FIX THIS.
				mtyp := check.typ(mdecl.Type, cycleOk).(*Signature)
				m.Type = mtyp
			}
		}

	case ast.Fun:
		fdecl := obj.Decl.(*ast.FuncDecl)
		if fdecl.Recv != nil {
			// This will ensure that the method base type is
			// type-checked
			check.collectFields(token.FUNC, fdecl.Recv, true)
		}
		ftyp := check.typ(fdecl.Type, cycleOk).(*Signature)
		obj.Type = ftyp
		check.function(ftyp, fdecl.Body)

	default:
		panic("unreachable")
	}
}

// obj type checks an object.
func (check *checker) obj(obj *ast.Object, cycleOk bool) {
	if trace {
		fmt.Printf("obj(%s)\n", obj.Name)
	}

	if obj.Type != nil {
		// object has already been type checked
		return
	}

	switch obj.Kind {
	case ast.Bad, ast.Pkg:
		// nothing to do

	case ast.Con:
		if obj.Data == nil {
			check.errorf(obj.Pos(), "illegal cycle in initialization of %s", obj.Name)
			return
		}
		spec, ok := obj.Decl.(*ast.ValueSpec)
		assert(ok)
		// The Data stored with the constant is the value of iota for that
		// ast.ValueSpec. Use it for the evaluation of the initialization
		// expressions.
		iota := obj.Data.(int)
		obj.Data = nil
		check.decl(spec.Pos(), obj, spec.Names, spec.Type, check.specValues(spec), iota)

	case ast.Var:
		// TODO(gri) missing cycle detection
		spec, ok := obj.Decl.(*ast.ValueSpec)
		if !ok {
			// TODO(gri) the assertion fails for "x, y := 1, 2, 3" it seems
			fmt.Printf("var = %s\n", obj.Name)
		}
		assert(ok)
		check.decl(spec.Pos(), obj, spec.Names, spec.Type, spec.Values, 0)

	case ast.Typ:
		typ := &NamedType{Obj: obj}
		obj.Type = typ // "mark" object so recursion terminates
		typ.Underlying = underlying(check.typ(obj.Decl.(*ast.TypeSpec).Type, cycleOk))
		// collect associated methods, if any
		if obj.Data != nil {
			scope := obj.Data.(*ast.Scope)
			// struct fields must not conflict with methods
			if t, ok := typ.Underlying.(*Struct); ok {
				for _, f := range t.Fields {
					if m := scope.Lookup(f.Name); m != nil {
						check.errorf(m.Pos(), "type %s has both field and method named %s", obj.Name, f.Name)
					}
				}
			}
			// collect methods
			methods := make(ObjList, len(scope.Objects))
			i := 0
			for _, m := range scope.Objects {
				methods[i] = m
				i++
			}
			methods.Sort()
			typ.Methods = methods
			// methods cannot be associated with an interface type
			// (do this check after sorting for reproducible error positions - needed for testing)
			if _, ok := typ.Underlying.(*Interface); ok {
				for _, m := range methods {
					recv := m.Decl.(*ast.FuncDecl).Recv.List[0].Type
					check.errorf(recv.Pos(), "invalid receiver type %s (%s is an interface type)", obj.Name, obj.Name)
				}
			}
		}

	case ast.Fun:
		fdecl := obj.Decl.(*ast.FuncDecl)
		ftyp := check.typ(fdecl.Type, cycleOk).(*Signature)
		obj.Type = ftyp
		if fdecl.Recv != nil {
			// TODO(gri) handle method receiver
		}
		check.stmt(fdecl.Body)

	default:
		panic("unreachable")
	}
}