+++ /dev/null
-// 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"
- "sort"
- "strconv"
-
- "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. If it's a named type, it should be exported.
- enclosing types.Type
-
- pkg Package
- qf types.Qualifier
-}
-
-type Declaration struct {
- MappedRange []MappedRange
- node ast.Node
- obj types.Object
-
- // typeSwitchImplicit indicates that the declaration is in an implicit
- // type switch. Its type is the type of the variable on the right-hand
- // side of the type switch.
- typeSwitchImplicit types.Type
-}
-
-// 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()
-
- pkgs, err := snapshot.PackagesForFile(ctx, fh.URI(), TypecheckAll)
- if err != nil {
- return nil, err
- }
- if len(pkgs) == 0 {
- return nil, fmt.Errorf("no packages for file %v", fh.URI())
- }
- sort.Slice(pkgs, func(i, j int) bool {
- return len(pkgs[i].CompiledGoFiles()) < len(pkgs[j].CompiledGoFiles())
- })
- var findErr error
- for _, pkg := range pkgs {
- pgf, err := pkg.File(fh.URI())
- if err != nil {
- return nil, err
- }
- spn, err := pgf.Mapper.PointSpan(pos)
- if err != nil {
- return nil, err
- }
- rng, err := spn.Range(pgf.Mapper.Converter)
- if err != nil {
- return nil, err
- }
- var ident *IdentifierInfo
- ident, findErr = findIdentifier(ctx, snapshot, pkg, pgf.File, rng.Start)
- if findErr == nil {
- return ident, nil
- }
- }
- return nil, findErr
-}
-
-// ErrNoIdentFound is error returned when no identifer is found at a particular position
-var ErrNoIdentFound = errors.New("no identifier found")
-
-func findIdentifier(ctx context.Context, snapshot 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(snapshot, pkg, file, pos); result != nil || err != nil {
- if snapshot.View().Options().ImportShortcut.ShowDefinition() {
- return result, err
- }
- return nil, nil
- }
- path := pathEnclosingObjNode(file, pos)
- if path == nil {
- return nil, ErrNoIdentFound
- }
-
- 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(snapshot, pkg, file.Name.Pos(), file.Name.End())
- if err != nil {
- return nil, err
- }
- var declAST *ast.File
- for _, pgf := range pkg.CompiledGoFiles() {
- if pgf.File.Doc != nil {
- declAST = pgf.File
- }
- }
- // If there's no package documentation, just use current file.
- if declAST == nil {
- declAST = file
- }
- declRng, err := posToMappedRange(snapshot, 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: snapshot,
- Declaration: Declaration{
- node: declAST.Name,
- MappedRange: []MappedRange{declRng},
- },
- }, nil
- }
-
- result := &IdentifierInfo{
- Snapshot: snapshot,
- qf: qf,
- pkg: pkg,
- ident: ident,
- enclosing: searchForEnclosing(pkg.GetTypesInfo(), 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(snapshot, 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, typ := 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]
- result.Declaration.typeSwitchImplicit = typ
- } else {
- // Probably a type error.
- return nil, errors.Errorf("%w for ident %v", errNoObjectFound, result.Name)
- }
- }
-
- // Handle builtins separately.
- if result.Declaration.obj.Parent() == types.Universe {
- builtin, err := snapshot.BuiltinPackage(ctx)
- if err != nil {
- return nil, err
- }
- builtinObj := builtin.Package.Scope.Lookup(result.Name)
- if builtinObj == nil {
- return nil, fmt.Errorf("no builtin object for %s", result.Name)
- }
- decl, ok := builtinObj.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.
- rng := NewMappedRange(snapshot.FileSet(), builtin.ParsedFile.Mapper, decl.Pos(), decl.Pos()+token.Pos(len(result.Name)))
- result.Declaration.MappedRange = append(result.Declaration.MappedRange, rng)
- return result, nil
- }
-
- // (error).Error is a special case of builtin. Lots of checks to confirm
- // that this is the builtin Error.
- if obj := result.Declaration.obj; obj.Parent() == nil && obj.Pkg() == nil && obj.Name() == "Error" {
- if _, ok := obj.Type().(*types.Signature); ok {
- builtin, err := snapshot.BuiltinPackage(ctx)
- if err != nil {
- return nil, err
- }
- // Look up "error" and then navigate to its only method.
- // The Error method does not appear in the builtin package's scope.log.Pri
- const errorName = "error"
- builtinObj := builtin.Package.Scope.Lookup(errorName)
- if builtinObj == nil {
- return nil, fmt.Errorf("no builtin object for %s", errorName)
- }
- decl, ok := builtinObj.Decl.(ast.Node)
- if !ok {
- return nil, errors.Errorf("no declaration for %s", errorName)
- }
- spec, ok := decl.(*ast.TypeSpec)
- if !ok {
- return nil, fmt.Errorf("no type spec for %s", errorName)
- }
- iface, ok := spec.Type.(*ast.InterfaceType)
- if !ok {
- return nil, fmt.Errorf("%s is not an interface", errorName)
- }
- if iface.Methods.NumFields() != 1 {
- return nil, fmt.Errorf("expected 1 method for %s, got %v", errorName, iface.Methods.NumFields())
- }
- method := iface.Methods.List[0]
- if len(method.Names) != 1 {
- return nil, fmt.Errorf("expected 1 name for %v, got %v", method, len(method.Names))
- }
- name := method.Names[0].Name
- result.Declaration.node = method
- rng := NewMappedRange(snapshot.FileSet(), builtin.ParsedFile.Mapper, method.Pos(), method.Pos()+token.Pos(len(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(snapshot, pkg, result.Declaration.obj)
- if err != nil {
- return nil, err
- }
- result.Declaration.MappedRange = append(result.Declaration.MappedRange, rng)
-
- if result.Declaration.node, err = objToDecl(ctx, snapshot, 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(snapshot, pkg, result.Type.Object); err != nil {
- return nil, err
- }
- }
- return result, nil
-}
-
-func searchForEnclosing(info *types.Info, path []ast.Node) types.Type {
- for _, n := range path {
- switch n := n.(type) {
- case *ast.SelectorExpr:
- if sel, ok := info.Selections[n]; ok {
- recv := Deref(sel.Recv())
-
- // Keep track of the last exported type seen.
- var exported types.Type
- if named, ok := recv.(*types.Named); ok && named.Obj().Exported() {
- exported = named
- }
- // We don't want the last element, as that's the field or
- // method itself.
- for _, index := range sel.Index()[:len(sel.Index())-1] {
- if r, ok := recv.Underlying().(*types.Struct); ok {
- recv = Deref(r.Field(index).Type())
- if named, ok := recv.(*types.Named); ok && named.Obj().Exported() {
- exported = named
- }
- }
- }
- return exported
- }
- case *ast.CompositeLit:
- if t, ok := info.Types[n]; ok {
- return t.Type
- }
- case *ast.TypeSpec:
- if _, ok := n.Type.(*ast.StructType); ok {
- if t, ok := info.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 objToDecl(ctx context.Context, snapshot Snapshot, srcPkg Package, obj types.Object) (ast.Decl, error) {
- pgf, _, err := FindPosInPackage(snapshot, srcPkg, obj.Pos())
- if err != nil {
- return nil, err
- }
- posToDecl, err := snapshot.PosToDecl(ctx, pgf)
- if err != nil {
- return nil, err
- }
- return posToDecl[obj.Pos()], nil
-}
-
-// importSpec handles positions inside of an *ast.ImportSpec.
-func importSpec(snapshot 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: snapshot,
- Name: importPath,
- pkg: pkg,
- }
- if result.MappedRange, err = posToMappedRange(snapshot, 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
- }
- // Return all of the files in the package as the definition of the import spec.
- for _, dst := range importedPkg.GetSyntax() {
- rng, err := posToMappedRange(snapshot, 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. It also returns the original type
-// associated with the identifier (outside of a case clause).
-func typeSwitchImplicits(pkg Package, path []ast.Node) ([]types.Object, types.Type) {
- ident, _ := path[0].(*ast.Ident)
- if ident == nil {
- return nil, 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, 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)
- }
- }
- // The right-hand side of a type switch should only have one
- // element, and we need to track its type in order to generate
- // hover information for implicit type switch variables.
- var typ types.Type
- if assign, ok := ts.Assign.(*ast.AssignStmt); ok && len(assign.Rhs) == 1 {
- if rhs := assign.Rhs[0].(*ast.TypeAssertExpr); ok {
- typ = pkg.GetTypesInfo().TypeOf(rhs.X)
- }
- }
- return objs, typ
-}
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