| // 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/span" |
| ) |
| |
| // IdentifierInfo holds information about an identifier in Go source. |
| type IdentifierInfo struct { |
| Name string |
| Range span.Range |
| File GoFile |
| Type struct { |
| Range span.Range |
| Object types.Object |
| } |
| decl declaration |
| |
| pkg Package |
| ident *ast.Ident |
| wasEmbeddedField bool |
| qf types.Qualifier |
| } |
| |
| type declaration struct { |
| rng span.Range |
| node ast.Node |
| obj types.Object |
| wasImplicit bool |
| } |
| |
| func (i *IdentifierInfo) DeclarationRange() span.Range { |
| return i.decl.rng |
| } |
| |
| // Identifier returns identifier information for a position |
| // in a file, accounting for a potentially incomplete selector. |
| func Identifier(ctx context.Context, view View, f GoFile, pos token.Pos) (*IdentifierInfo, error) { |
| if result, err := identifier(ctx, view, f, pos); err != nil || result != nil { |
| return result, err |
| } |
| // If the position is not an identifier but immediately follows |
| // an identifier or selector period (as is common when |
| // requesting a completion), use the path to the preceding node. |
| result, err := identifier(ctx, view, f, pos-1) |
| if result == nil && err == nil { |
| err = fmt.Errorf("no identifier found") |
| } |
| return result, err |
| } |
| |
| // identifier checks a single position for a potential identifier. |
| func identifier(ctx context.Context, view View, f GoFile, pos token.Pos) (*IdentifierInfo, error) { |
| file := f.GetAST(ctx) |
| if file == nil { |
| return nil, fmt.Errorf("no AST for %s", f.URI()) |
| } |
| pkg := f.GetPackage(ctx) |
| if pkg == nil || pkg.IsIllTyped() { |
| return nil, fmt.Errorf("pkg for %s is ill-typed", f.URI()) |
| } |
| // Handle import specs separately, as there is no formal position for a package declaration. |
| if result, err := importSpec(ctx, f, file, pkg, pos); result != nil || err != nil { |
| return result, err |
| } |
| path, _ := astutil.PathEnclosingInterval(file, pos, pos) |
| if path == nil { |
| return nil, fmt.Errorf("can't find node enclosing position") |
| } |
| result := &IdentifierInfo{ |
| File: f, |
| qf: qualifier(file, pkg.GetTypes(), pkg.GetTypesInfo()), |
| pkg: pkg, |
| } |
| |
| switch node := path[0].(type) { |
| case *ast.Ident: |
| result.ident = node |
| case *ast.SelectorExpr: |
| result.ident = node.Sel |
| } |
| if result.ident == nil { |
| return nil, nil |
| } |
| for _, n := range path[1:] { |
| if field, ok := n.(*ast.Field); ok { |
| result.wasEmbeddedField = len(field.Names) == 0 |
| break |
| } |
| } |
| result.Name = result.ident.Name |
| result.Range = span.NewRange(f.FileSet(), result.ident.Pos(), result.ident.End()) |
| result.decl.obj = pkg.GetTypesInfo().ObjectOf(result.ident) |
| if result.decl.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 := typeSwitchVar(pkg.GetTypesInfo(), 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.decl.obj = objs[0] |
| result.decl.wasImplicit = true |
| } else { |
| // Probably a type error. |
| return nil, fmt.Errorf("no object for ident %v", result.Name) |
| } |
| } |
| |
| var err error |
| |
| // Handle builtins separately. |
| if result.decl.obj.Parent() == types.Universe { |
| decl, ok := lookupBuiltinDecl(f.View(), result.Name).(ast.Node) |
| if !ok { |
| return nil, fmt.Errorf("no declaration for %s", result.Name) |
| } |
| result.decl.node = decl |
| if result.decl.rng, err = posToRange(ctx, f.FileSet(), result.Name, decl.Pos()); err != nil { |
| return nil, err |
| } |
| return result, nil |
| } |
| |
| if result.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.decl.obj.(*types.Var); ok { |
| if typObj := typeToObject(v.Type()); typObj != nil { |
| result.decl.obj = typObj |
| } |
| } |
| } |
| |
| for _, obj := range pkg.GetTypesInfo().Implicits { |
| if obj.Pos() == result.decl.obj.Pos() { |
| // Mark this declaration as implicit, since it will not |
| // appear in a (*types.Info).Defs map. |
| result.decl.wasImplicit = true |
| break |
| } |
| } |
| |
| if result.decl.rng, err = objToRange(ctx, f.FileSet(), result.decl.obj); err != nil { |
| return nil, err |
| } |
| if result.decl.node, err = objToNode(ctx, view, pkg.GetTypes(), result.decl.obj, result.decl.rng); 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.Range, err = objToRange(ctx, f.FileSet(), result.Type.Object); err != nil { |
| return nil, err |
| } |
| } |
| return result, 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 objToRange(ctx context.Context, fset *token.FileSet, obj types.Object) (span.Range, error) { |
| if pkgName, ok := obj.(*types.PkgName); ok { |
| // An imported Go package has a package-local, unqualified name. |
| // When the name matches the imported package name, there is no |
| // identifier in the import spec with the local package name. |
| // |
| // For example: |
| // import "go/ast" // name "ast" matches package name |
| // import a "go/ast" // name "a" does not match package name |
| // |
| // When the identifier does not appear in the source, have the range |
| // of the object be the point at the beginning of the declaration. |
| if pkgName.Imported().Name() == pkgName.Name() { |
| return posToRange(ctx, fset, "", obj.Pos()) |
| } |
| } |
| return posToRange(ctx, fset, obj.Name(), obj.Pos()) |
| } |
| |
| func posToRange(ctx context.Context, fset *token.FileSet, name string, pos token.Pos) (span.Range, error) { |
| if !pos.IsValid() { |
| return span.Range{}, fmt.Errorf("invalid position for %v", name) |
| } |
| return span.NewRange(fset, pos, pos+token.Pos(len(name))), nil |
| } |
| |
| func objToNode(ctx context.Context, view View, originPkg *types.Package, obj types.Object, rng span.Range) (ast.Decl, error) { |
| s, err := rng.Span() |
| if err != nil { |
| return nil, err |
| } |
| f, err := view.GetFile(ctx, s.URI()) |
| if err != nil { |
| return nil, err |
| } |
| declFile, ok := f.(GoFile) |
| if !ok { |
| return nil, fmt.Errorf("%s is not a Go file", s.URI()) |
| } |
| // If the object is exported from a different package, |
| // we don't need its full AST to find the definition. |
| var declAST *ast.File |
| if obj.Exported() && obj.Pkg() != originPkg { |
| declAST = declFile.GetAnyAST(ctx) |
| } else { |
| declAST = declFile.GetAST(ctx) |
| } |
| if declAST == nil { |
| return nil, fmt.Errorf("no AST for %s", f.URI()) |
| } |
| path, _ := astutil.PathEnclosingInterval(declAST, rng.Start, rng.End) |
| if path == nil { |
| return nil, fmt.Errorf("no path for range %v", rng) |
| } |
| 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(ctx context.Context, f GoFile, fAST *ast.File, pkg Package, pos token.Pos) (*IdentifierInfo, error) { |
| var imp *ast.ImportSpec |
| for _, spec := range fAST.Imports { |
| if spec.Pos() <= pos && pos < spec.End() { |
| imp = spec |
| } |
| } |
| if imp == nil { |
| return nil, nil |
| } |
| importPath, err := strconv.Unquote(imp.Path.Value) |
| if err != nil { |
| return nil, fmt.Errorf("import path not quoted: %s (%v)", imp.Path.Value, err) |
| } |
| result := &IdentifierInfo{ |
| File: f, |
| Name: importPath, |
| Range: span.NewRange(f.FileSet(), imp.Pos(), imp.End()), |
| pkg: pkg, |
| } |
| // Consider the "declaration" of an import spec to be the imported package. |
| importedPkg := pkg.GetImport(importPath) |
| if importedPkg == nil { |
| return nil, fmt.Errorf("no import for %q", importPath) |
| } |
| if importedPkg.GetSyntax() == nil { |
| return nil, fmt.Errorf("no syntax for for %q", importPath) |
| } |
| // Heuristic: Jump to the longest (most "interesting") file of the package. |
| var dest *ast.File |
| for _, f := range importedPkg.GetSyntax() { |
| if dest == nil || f.End()-f.Pos() > dest.End()-dest.Pos() { |
| dest = f |
| } |
| } |
| if dest == nil { |
| return nil, fmt.Errorf("package %q has no files", importPath) |
| } |
| result.decl.rng = span.NewRange(f.FileSet(), dest.Name.Pos(), dest.Name.End()) |
| return result, nil |
| } |
| |
| // typeSwitchVar handles the special case of a local variable implicitly defined in a type switch. |
| // In such cases, the definition of the implicit variable will not be recorded in the *types.Info.Defs map, |
| // but rather in the *types.Info.Implicits map. |
| func typeSwitchVar(info *types.Info, path []ast.Node) []types.Object { |
| if len(path) < 3 { |
| return nil |
| } |
| // Check for [Ident AssignStmt TypeSwitchStmt...] |
| if _, ok := path[0].(*ast.Ident); !ok { |
| return nil |
| } |
| if _, ok := path[1].(*ast.AssignStmt); !ok { |
| return nil |
| } |
| sw, ok := path[2].(*ast.TypeSwitchStmt) |
| if !ok { |
| return nil |
| } |
| |
| var res []types.Object |
| for _, stmt := range sw.Body.List { |
| obj := info.Implicits[stmt.(*ast.CaseClause)] |
| if obj != nil { |
| res = append(res, obj) |
| } |
| } |
| return res |
| } |