| // Copyright 2018 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 source |
| |
| import ( |
| "context" |
| "fmt" |
| "go/ast" |
| "go/token" |
| "go/types" |
| "strconv" |
| |
| "golang.org/x/tools/go/ast/astutil" |
| "golang.org/x/tools/internal/event" |
| "golang.org/x/tools/internal/lsp/protocol" |
| errors "golang.org/x/xerrors" |
| ) |
| |
| // IdentifierInfo holds information about an identifier in Go source. |
| type IdentifierInfo struct { |
| Name string |
| Snapshot Snapshot |
| mappedRange |
| |
| Type struct { |
| mappedRange |
| Object types.Object |
| } |
| |
| Declaration Declaration |
| |
| ident *ast.Ident |
| |
| // enclosing is an expression used to determine the link anchor for an identifier. |
| enclosing types.Type |
| |
| pkg Package |
| qf types.Qualifier |
| } |
| |
| type Declaration struct { |
| MappedRange []mappedRange |
| node ast.Node |
| obj types.Object |
| } |
| |
| // Identifier returns identifier information for a position |
| // in a file, accounting for a potentially incomplete selector. |
| func Identifier(ctx context.Context, snapshot Snapshot, fh FileHandle, pos protocol.Position) (*IdentifierInfo, error) { |
| ctx, done := event.Start(ctx, "source.Identifier") |
| defer done() |
| |
| pkg, pgh, err := getParsedFile(ctx, snapshot, fh, NarrowestPackageHandle) |
| if err != nil { |
| return nil, fmt.Errorf("getting file for Identifier: %w", err) |
| } |
| file, _, m, _, err := pgh.Cached() |
| if err != nil { |
| return nil, err |
| } |
| spn, err := m.PointSpan(pos) |
| if err != nil { |
| return nil, err |
| } |
| rng, err := spn.Range(m.Converter) |
| if err != nil { |
| return nil, err |
| } |
| return findIdentifier(ctx, snapshot, pkg, file, rng.Start) |
| } |
| |
| var ErrNoIdentFound = errors.New("no identifier found") |
| |
| func findIdentifier(ctx context.Context, s Snapshot, pkg Package, file *ast.File, pos token.Pos) (*IdentifierInfo, error) { |
| // Handle import specs separately, as there is no formal position for a package declaration. |
| if result, err := importSpec(s, pkg, file, pos); result != nil || err != nil { |
| return result, err |
| } |
| path := pathEnclosingObjNode(file, pos) |
| if path == nil { |
| return nil, ErrNoIdentFound |
| } |
| |
| view := s.View() |
| qf := qualifier(file, pkg.GetTypes(), pkg.GetTypesInfo()) |
| |
| ident, _ := path[0].(*ast.Ident) |
| if ident == nil { |
| return nil, ErrNoIdentFound |
| } |
| // Special case for package declarations, since they have no |
| // corresponding types.Object. |
| if ident == file.Name { |
| rng, err := posToMappedRange(view, pkg, file.Name.Pos(), file.Name.End()) |
| if err != nil { |
| return nil, err |
| } |
| var declAST *ast.File |
| for _, f := range pkg.GetSyntax() { |
| if f.Doc != nil { |
| declAST = f |
| } |
| } |
| // If there's no package documentation, just use current file. |
| if declAST == nil { |
| declAST = file |
| } |
| declRng, err := posToMappedRange(view, pkg, declAST.Name.Pos(), declAST.Name.End()) |
| if err != nil { |
| return nil, err |
| } |
| return &IdentifierInfo{ |
| Name: file.Name.Name, |
| ident: file.Name, |
| mappedRange: rng, |
| pkg: pkg, |
| qf: qf, |
| Snapshot: s, |
| Declaration: Declaration{ |
| node: declAST.Name, |
| MappedRange: []mappedRange{declRng}, |
| }, |
| }, nil |
| } |
| |
| result := &IdentifierInfo{ |
| Snapshot: s, |
| qf: qf, |
| pkg: pkg, |
| ident: ident, |
| enclosing: searchForEnclosing(pkg, path), |
| } |
| |
| var wasEmbeddedField bool |
| for _, n := range path[1:] { |
| if field, ok := n.(*ast.Field); ok { |
| wasEmbeddedField = len(field.Names) == 0 |
| break |
| } |
| } |
| |
| result.Name = result.ident.Name |
| var err error |
| if result.mappedRange, err = posToMappedRange(view, pkg, result.ident.Pos(), result.ident.End()); err != nil { |
| return nil, err |
| } |
| |
| result.Declaration.obj = pkg.GetTypesInfo().ObjectOf(result.ident) |
| if result.Declaration.obj == nil { |
| // If there was no types.Object for the declaration, there might be an implicit local variable |
| // declaration in a type switch. |
| if objs := typeSwitchImplicits(pkg, path); len(objs) > 0 { |
| // There is no types.Object for the declaration of an implicit local variable, |
| // but all of the types.Objects associated with the usages of this variable can be |
| // used to connect it back to the declaration. |
| // Preserve the first of these objects and treat it as if it were the declaring object. |
| result.Declaration.obj = objs[0] |
| } else { |
| // Probably a type error. |
| return nil, errors.Errorf("no object for ident %v", result.Name) |
| } |
| } |
| |
| // Handle builtins separately. |
| if result.Declaration.obj.Parent() == types.Universe { |
| builtin, err := view.BuiltinPackage(ctx) |
| if err != nil { |
| return nil, err |
| } |
| decl, ok := builtin.Package().Scope.Lookup(result.Name).Decl.(ast.Node) |
| if !ok { |
| return nil, errors.Errorf("no declaration for %s", result.Name) |
| } |
| result.Declaration.node = decl |
| |
| // The builtin package isn't in the dependency graph, so the usual utilities |
| // won't work here. |
| _, _, m, _, err := builtin.ParseGoHandle().Cached() |
| if err != nil { |
| return nil, err |
| } |
| rng := newMappedRange(view.Session().Cache().FileSet(), m, decl.Pos(), decl.Pos()+token.Pos(len(result.Name))) |
| result.Declaration.MappedRange = append(result.Declaration.MappedRange, rng) |
| |
| return result, nil |
| } |
| |
| if wasEmbeddedField { |
| // The original position was on the embedded field declaration, so we |
| // try to dig out the type and jump to that instead. |
| if v, ok := result.Declaration.obj.(*types.Var); ok { |
| if typObj := typeToObject(v.Type()); typObj != nil { |
| result.Declaration.obj = typObj |
| } |
| } |
| } |
| |
| rng, err := objToMappedRange(view, pkg, result.Declaration.obj) |
| if err != nil { |
| return nil, err |
| } |
| result.Declaration.MappedRange = append(result.Declaration.MappedRange, rng) |
| |
| if result.Declaration.node, err = objToNode(s.View(), pkg, result.Declaration.obj); err != nil { |
| return nil, err |
| } |
| typ := pkg.GetTypesInfo().TypeOf(result.ident) |
| if typ == nil { |
| return result, nil |
| } |
| |
| result.Type.Object = typeToObject(typ) |
| if result.Type.Object != nil { |
| // Identifiers with the type "error" are a special case with no position. |
| if hasErrorType(result.Type.Object) { |
| return result, nil |
| } |
| if result.Type.mappedRange, err = objToMappedRange(view, pkg, result.Type.Object); err != nil { |
| return nil, err |
| } |
| } |
| return result, nil |
| } |
| |
| func searchForEnclosing(pkg Package, path []ast.Node) types.Type { |
| for _, n := range path { |
| switch n := n.(type) { |
| case *ast.SelectorExpr: |
| if selection, ok := pkg.GetTypesInfo().Selections[n]; ok { |
| return deref(selection.Recv()) |
| } |
| case *ast.CompositeLit: |
| if t, ok := pkg.GetTypesInfo().Types[n]; ok { |
| return t.Type |
| } |
| case *ast.TypeSpec: |
| if _, ok := n.Type.(*ast.StructType); ok { |
| if t, ok := pkg.GetTypesInfo().Defs[n.Name]; ok { |
| return t.Type() |
| } |
| } |
| } |
| } |
| return nil |
| } |
| |
| func typeToObject(typ types.Type) types.Object { |
| switch typ := typ.(type) { |
| case *types.Named: |
| return typ.Obj() |
| case *types.Pointer: |
| return typeToObject(typ.Elem()) |
| default: |
| return nil |
| } |
| } |
| |
| func hasErrorType(obj types.Object) bool { |
| return types.IsInterface(obj.Type()) && obj.Pkg() == nil && obj.Name() == "error" |
| } |
| |
| func objToNode(v View, pkg Package, obj types.Object) (ast.Decl, error) { |
| declAST, _, err := findPosInPackage(v, pkg, obj.Pos()) |
| if err != nil { |
| return nil, err |
| } |
| path, _ := astutil.PathEnclosingInterval(declAST, obj.Pos(), obj.Pos()) |
| if path == nil { |
| return nil, errors.Errorf("no path for object %v", obj.Name()) |
| } |
| for _, node := range path { |
| switch node := node.(type) { |
| case *ast.GenDecl: |
| // Type names, fields, and methods. |
| switch obj.(type) { |
| case *types.TypeName, *types.Var, *types.Const, *types.Func: |
| return node, nil |
| } |
| case *ast.FuncDecl: |
| // Function signatures. |
| if _, ok := obj.(*types.Func); ok { |
| return node, nil |
| } |
| } |
| } |
| return nil, nil // didn't find a node, but don't fail |
| } |
| |
| // importSpec handles positions inside of an *ast.ImportSpec. |
| func importSpec(s Snapshot, pkg Package, file *ast.File, pos token.Pos) (*IdentifierInfo, error) { |
| var imp *ast.ImportSpec |
| for _, spec := range file.Imports { |
| if spec.Path.Pos() <= pos && pos < spec.Path.End() { |
| imp = spec |
| } |
| } |
| if imp == nil { |
| return nil, nil |
| } |
| importPath, err := strconv.Unquote(imp.Path.Value) |
| if err != nil { |
| return nil, errors.Errorf("import path not quoted: %s (%v)", imp.Path.Value, err) |
| } |
| result := &IdentifierInfo{ |
| Snapshot: s, |
| Name: importPath, |
| pkg: pkg, |
| } |
| if result.mappedRange, err = posToMappedRange(s.View(), pkg, imp.Path.Pos(), imp.Path.End()); err != nil { |
| return nil, err |
| } |
| // Consider the "declaration" of an import spec to be the imported package. |
| importedPkg, err := pkg.GetImport(importPath) |
| if err != nil { |
| return nil, err |
| } |
| if importedPkg.GetSyntax() == nil { |
| return nil, errors.Errorf("no syntax for for %q", importPath) |
| } |
| // Return all of the files in the package as the definition of the import spec. |
| dest := pkg.GetSyntax() |
| if len(dest) == 0 { |
| return nil, errors.Errorf("package %q has no files", importPath) |
| } |
| |
| for _, dst := range importedPkg.GetSyntax() { |
| rng, err := posToMappedRange(s.View(), pkg, dst.Pos(), dst.End()) |
| if err != nil { |
| return nil, err |
| } |
| result.Declaration.MappedRange = append(result.Declaration.MappedRange, rng) |
| } |
| |
| result.Declaration.node = imp |
| return result, nil |
| } |
| |
| // typeSwitchImplicits returns all the implicit type switch objects |
| // that correspond to the leaf *ast.Ident. |
| func typeSwitchImplicits(pkg Package, path []ast.Node) []types.Object { |
| ident, _ := path[0].(*ast.Ident) |
| if ident == nil { |
| return nil |
| } |
| |
| var ( |
| ts *ast.TypeSwitchStmt |
| assign *ast.AssignStmt |
| cc *ast.CaseClause |
| obj = pkg.GetTypesInfo().ObjectOf(ident) |
| ) |
| |
| // Walk our ancestors to determine if our leaf ident refers to a |
| // type switch variable, e.g. the "a" from "switch a := b.(type)". |
| Outer: |
| for i := 1; i < len(path); i++ { |
| switch n := path[i].(type) { |
| case *ast.AssignStmt: |
| // Check if ident is the "a" in "a := foo.(type)". The "a" in |
| // this case has no types.Object, so check for ident equality. |
| if len(n.Lhs) == 1 && n.Lhs[0] == ident { |
| assign = n |
| } |
| case *ast.CaseClause: |
| // Check if ident is a use of "a" within a case clause. Each |
| // case clause implicitly maps "a" to a different types.Object, |
| // so check if ident's object is the case clause's implicit |
| // object. |
| if obj != nil && pkg.GetTypesInfo().Implicits[n] == obj { |
| cc = n |
| } |
| case *ast.TypeSwitchStmt: |
| // Look for the type switch that owns our previously found |
| // *ast.AssignStmt or *ast.CaseClause. |
| |
| if n.Assign == assign { |
| ts = n |
| break Outer |
| } |
| |
| for _, stmt := range n.Body.List { |
| if stmt == cc { |
| ts = n |
| break Outer |
| } |
| } |
| } |
| } |
| |
| if ts == nil { |
| return nil |
| } |
| |
| // Our leaf ident refers to a type switch variable. Fan out to the |
| // type switch's implicit case clause objects. |
| var objs []types.Object |
| for _, cc := range ts.Body.List { |
| if ccObj := pkg.GetTypesInfo().Implicits[cc]; ccObj != nil { |
| objs = append(objs, ccObj) |
| } |
| } |
| return objs |
| } |