gopls/internal/golang/util.go - tools - Git at Google

 // Copyright 2019 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 golang

 import (
 	"context"
 	"go/ast"
 	"go/printer"
 	"go/token"
 	"go/types"
 	"regexp"
 	"strings"

 	"golang.org/x/tools/gopls/internal/cache"
 	"golang.org/x/tools/gopls/internal/cache/metadata"
 	"golang.org/x/tools/gopls/internal/cache/parsego"
 	"golang.org/x/tools/gopls/internal/protocol"
 	"golang.org/x/tools/gopls/internal/util/astutil"
 	"golang.org/x/tools/gopls/internal/util/bug"
 	"golang.org/x/tools/gopls/internal/util/safetoken"
 	"golang.org/x/tools/internal/tokeninternal"
 )

 // IsGenerated gets and reads the file denoted by uri and reports
 // whether it contains a "generated file" comment as described at
 // https://golang.org/s/generatedcode.
 //
 // TODO(adonovan): opt: this function does too much.
 // Move snapshot.ReadFile into the caller (most of which have already done it).
 func IsGenerated(ctx context.Context, snapshot *cache.Snapshot, uri protocol.DocumentURI) bool {
 	fh, err := snapshot.ReadFile(ctx, uri)
 	if err != nil {
 		return false
 	}
 	pgf, err := snapshot.ParseGo(ctx, fh, parsego.Header)
 	if err != nil {
 		return false
 	}
 	for _, commentGroup := range pgf.File.Comments {
 		for _, comment := range commentGroup.List {
 			if matched := generatedRx.MatchString(comment.Text); matched {
 				// Check if comment is at the beginning of the line in source.
 				if safetoken.Position(pgf.Tok, comment.Slash).Column == 1 {
 					return true
 				}
 			}
 		}
 	}
 	return false
 }

 // adjustedObjEnd returns the end position of obj, possibly modified for
 // package names.
 //
 // TODO(rfindley): eliminate this function, by inlining it at callsites where
 // it makes sense.
 func adjustedObjEnd(obj types.Object) token.Pos {
 	nameLen := len(obj.Name())
 	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 import path, including quotes.
 		if pkgName.Imported().Name() == pkgName.Name() {
 			nameLen = len(pkgName.Imported().Path()) + len(`""`)
 		}
 	}
 	return obj.Pos() + token.Pos(nameLen)
 }

 // Matches cgo generated comment as well as the proposed standard:
 //
 //	https://golang.org/s/generatedcode
 var generatedRx = regexp.MustCompile(`// .*DO NOT EDIT\.?`)

 // nodeAtPos returns the index and the node whose position is contained inside
 // the node list.
 func nodeAtPos(nodes []ast.Node, pos token.Pos) (ast.Node, int) {
 	if nodes == nil {
 		return nil, -1
 	}
 	for i, node := range nodes {
 		if node.Pos() <= pos && pos <= node.End() {
 			return node, i
 		}
 	}
 	return nil, -1
 }

 // FormatNode returns the "pretty-print" output for an ast node.
 func FormatNode(fset *token.FileSet, n ast.Node) string {
 	var buf strings.Builder
 	if err := printer.Fprint(&buf, fset, n); err != nil {
 		// TODO(rfindley): we should use bug.Reportf here.
 		// We encounter this during completion.resolveInvalid.
 		return ""
 	}
 	return buf.String()
 }

 // FormatNodeFile is like FormatNode, but requires only the token.File for the
 // syntax containing the given ast node.
 func FormatNodeFile(file *token.File, n ast.Node) string {
 	fset := tokeninternal.FileSetFor(file)
 	return FormatNode(fset, n)
 }

 // findFileInDeps finds package metadata containing URI in the transitive
 // dependencies of m. When using the Go command, the answer is unique.
 func findFileInDeps(s metadata.Source, mp *metadata.Package, uri protocol.DocumentURI) *metadata.Package {
 	seen := make(map[PackageID]bool)
 	var search func(*metadata.Package) *metadata.Package
 	search = func(mp *metadata.Package) *metadata.Package {
 		if seen[mp.ID] {
 			return nil
 		}
 		seen[mp.ID] = true
 		for _, cgf := range mp.CompiledGoFiles {
 			if cgf == uri {
 				return mp
 			}
 		}
 		for _, dep := range mp.DepsByPkgPath {
 			mp := s.Metadata(dep)
 			if mp == nil {
 				bug.Reportf("nil metadata for %q", dep)
 				continue
 			}
 			if found := search(mp); found != nil {
 				return found
 			}
 		}
 		return nil
 	}
 	return search(mp)
 }

 // CollectScopes returns all scopes in an ast path, ordered as innermost scope
 // first.
 func CollectScopes(info *types.Info, path []ast.Node, pos token.Pos) []*types.Scope {
 	// scopes[i], where i<len(path), is the possibly nil Scope of path[i].
 	var scopes []*types.Scope
 	for _, n := range path {
 		// Include *FuncType scope if pos is inside the function body.
 		switch node := n.(type) {
 		case *ast.FuncDecl:
 			if node.Body != nil && astutil.NodeContains(node.Body, pos) {
 				n = node.Type
 			}
 		case *ast.FuncLit:
 			if node.Body != nil && astutil.NodeContains(node.Body, pos) {
 				n = node.Type
 			}
 		}
 		scopes = append(scopes, info.Scopes[n])
 	}
 	return scopes
 }

 // requalifier returns a function that re-qualifies identifiers and qualified
 // identifiers contained in targetFile using the given metadata qualifier.
 func requalifier(s metadata.Source, targetFile *ast.File, targetMeta *metadata.Package, mq MetadataQualifier) func(string) string {
 	qm := map[string]string{
 		"": mq(targetMeta.Name, "", targetMeta.PkgPath),
 	}

 	// Construct mapping of import paths to their defined or implicit names.
 	for _, imp := range targetFile.Imports {
 		name, pkgName, impPath, pkgPath := importInfo(s, imp, targetMeta)

 		// Re-map the target name for the source file.
 		qm[name] = mq(pkgName, impPath, pkgPath)
 	}

 	return func(name string) string {
 		if newName, ok := qm[name]; ok {
 			return newName
 		}
 		return name
 	}
 }

 // A MetadataQualifier is a function that qualifies an identifier declared in a
 // package with the given package name, import path, and package path.
 //
 // In scenarios where metadata is missing the provided PackageName and
 // PackagePath may be empty, but ImportPath must always be non-empty.
 type MetadataQualifier func(PackageName, ImportPath, PackagePath) string

 // MetadataQualifierForFile returns a metadata qualifier that chooses the best
 // qualification of an imported package relative to the file f in package with
 // metadata m.
 func MetadataQualifierForFile(s metadata.Source, f *ast.File, mp *metadata.Package) MetadataQualifier {
 	// Record local names for import paths.
 	localNames := make(map[ImportPath]string) // local names for imports in f
 	for _, imp := range f.Imports {
 		name, _, impPath, _ := importInfo(s, imp, mp)
 		localNames[impPath] = name
 	}

 	// Record a package path -> import path mapping.
 	inverseDeps := make(map[PackageID]PackagePath)
 	for path, id := range mp.DepsByPkgPath {
 		inverseDeps[id] = path
 	}
 	importsByPkgPath := make(map[PackagePath]ImportPath) // best import paths by pkgPath
 	for impPath, id := range mp.DepsByImpPath {
 		if id == "" {
 			continue
 		}
 		pkgPath := inverseDeps[id]
 		_, hasPath := importsByPkgPath[pkgPath]
 		_, hasImp := localNames[impPath]
 		// In rare cases, there may be multiple import paths with the same package
 		// path. In such scenarios, prefer an import path that already exists in
 		// the file.
 		if !hasPath || hasImp {
 			importsByPkgPath[pkgPath] = impPath
 		}
 	}

 	return func(pkgName PackageName, impPath ImportPath, pkgPath PackagePath) string {
 		// If supplied, translate the package path to an import path in the source
 		// package.
 		if pkgPath != "" {
 			if srcImp := importsByPkgPath[pkgPath]; srcImp != "" {
 				impPath = srcImp
 			}
 			if pkgPath == mp.PkgPath {
 				return ""
 			}
 		}
 		if localName, ok := localNames[impPath]; ok && impPath != "" {
 			return localName
 		}
 		if pkgName != "" {
 			return string(pkgName)
 		}
 		idx := strings.LastIndexByte(string(impPath), '/')
 		return string(impPath[idx+1:])
 	}
 }

 // importInfo collects information about the import specified by imp,
 // extracting its file-local name, package name, import path, and package path.
 //
 // If metadata is missing for the import, the resulting package name and
 // package path may be empty, and the file local name may be guessed based on
 // the import path.
 //
 // Note: previous versions of this helper used a PackageID->PackagePath map
 // extracted from m, for extracting package path even in the case where
 // metadata for a dep was missing. This should not be necessary, as we should
 // always have metadata for IDs contained in DepsByPkgPath.
 func importInfo(s metadata.Source, imp *ast.ImportSpec, mp *metadata.Package) (string, PackageName, ImportPath, PackagePath) {
 	var (
 		name    string // local name
 		pkgName PackageName
 		impPath = metadata.UnquoteImportPath(imp)
 		pkgPath PackagePath
 	)

 	// If the import has a local name, use it.
 	if imp.Name != nil {
 		name = imp.Name.Name
 	}

 	// Try to find metadata for the import. If successful and there is no local
 	// name, the package name is the local name.
 	if depID := mp.DepsByImpPath[impPath]; depID != "" {
 		if depMP := s.Metadata(depID); depMP != nil {
 			if name == "" {
 				name = string(depMP.Name)
 			}
 			pkgName = depMP.Name
 			pkgPath = depMP.PkgPath
 		}
 	}

 	// If the local name is still unknown, guess it based on the import path.
 	if name == "" {
 		idx := strings.LastIndexByte(string(impPath), '/')
 		name = string(impPath[idx+1:])
 	}
 	return name, pkgName, impPath, pkgPath
 }

 // isDirective reports whether c is a comment directive.
 //
 // Copied and adapted from go/src/go/ast/ast.go.
 func isDirective(c string) bool {
 	if len(c) < 3 {
 		return false
 	}
 	if c[1] != '/' {
 		return false
 	}
 	//-style comment (no newline at the end)
 	c = c[2:]
 	if len(c) == 0 {
 		// empty line
 		return false
 	}
 	// "//line " is a line directive.
 	// (The // has been removed.)
 	if strings.HasPrefix(c, "line ") {
 		return true
 	}

 	// "//[a-z0-9]+:[a-z0-9]"
 	// (The // has been removed.)
 	colon := strings.Index(c, ":")
 	if colon <= 0 || colon+1 >= len(c) {
 		return false
 	}
 	for i := 0; i <= colon+1; i++ {
 		if i == colon {
 			continue
 		}
 		b := c[i]
 		if !('a' <= b && b <= 'z' || '0' <= b && b <= '9') {
 			return false
 		}
 	}
 	return true
 }

 // embeddedIdent returns the type name identifier for an embedding x, if x in a
 // valid embedding. Otherwise, it returns nil.
 //
 // Spec: An embedded field must be specified as a type name T or as a pointer
 // to a non-interface type name *T
 func embeddedIdent(x ast.Expr) *ast.Ident {
 	if star, ok := x.(*ast.StarExpr); ok {
 		x = star.X
 	}
 	switch ix := x.(type) { // check for instantiated receivers
 	case *ast.IndexExpr:
 		x = ix.X
 	case *ast.IndexListExpr:
 		x = ix.X
 	}
 	switch x := x.(type) {
 	case *ast.Ident:
 		return x
 	case *ast.SelectorExpr:
 		if _, ok := x.X.(*ast.Ident); ok {
 			return x.Sel
 		}
 	}
 	return nil
 }

 // An importFunc is an implementation of the single-method
 // types.Importer interface based on a function value.
 type ImporterFunc func(path string) (*types.Package, error)

 func (f ImporterFunc) Import(path string) (*types.Package, error) { return f(path) }
	// Copyright 2019 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 golang

	import (
	"context"
	"go/ast"
	"go/printer"
	"go/token"
	"go/types"
	"regexp"
	"strings"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/astutil"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/tokeninternal"
	)

	// IsGenerated gets and reads the file denoted by uri and reports
	// whether it contains a "generated file" comment as described at
	// https://golang.org/s/generatedcode.
	//
	// TODO(adonovan): opt: this function does too much.
	// Move snapshot.ReadFile into the caller (most of which have already done it).
	func IsGenerated(ctx context.Context, snapshot *cache.Snapshot, uri protocol.DocumentURI) bool {
	fh, err := snapshot.ReadFile(ctx, uri)
	if err != nil {
	return false
	}
	pgf, err := snapshot.ParseGo(ctx, fh, parsego.Header)
	if err != nil {
	return false
	}
	for _, commentGroup := range pgf.File.Comments {
	for _, comment := range commentGroup.List {
	if matched := generatedRx.MatchString(comment.Text); matched {
	// Check if comment is at the beginning of the line in source.
	if safetoken.Position(pgf.Tok, comment.Slash).Column == 1 {
	return true
	}
	}
	}
	}
	return false
	}

	// adjustedObjEnd returns the end position of obj, possibly modified for
	// package names.
	//
	// TODO(rfindley): eliminate this function, by inlining it at callsites where
	// it makes sense.
	func adjustedObjEnd(obj types.Object) token.Pos {
	nameLen := len(obj.Name())
	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 import path, including quotes.
	if pkgName.Imported().Name() == pkgName.Name() {
	nameLen = len(pkgName.Imported().Path()) + len(`""`)
	}
	}
	return obj.Pos() + token.Pos(nameLen)
	}

	// Matches cgo generated comment as well as the proposed standard:
	//
	// https://golang.org/s/generatedcode
	var generatedRx = regexp.MustCompile(`// .*DO NOT EDIT\.?`)

	// nodeAtPos returns the index and the node whose position is contained inside
	// the node list.
	func nodeAtPos(nodes []ast.Node, pos token.Pos) (ast.Node, int) {
	if nodes == nil {
	return nil, -1
	}
	for i, node := range nodes {
	if node.Pos() <= pos && pos <= node.End() {
	return node, i
	}
	}
	return nil, -1
	}

	// FormatNode returns the "pretty-print" output for an ast node.
	func FormatNode(fset *token.FileSet, n ast.Node) string {
	var buf strings.Builder
	if err := printer.Fprint(&buf, fset, n); err != nil {
	// TODO(rfindley): we should use bug.Reportf here.
	// We encounter this during completion.resolveInvalid.
	return ""
	}
	return buf.String()
	}

	// FormatNodeFile is like FormatNode, but requires only the token.File for the
	// syntax containing the given ast node.
	func FormatNodeFile(file *token.File, n ast.Node) string {
	fset := tokeninternal.FileSetFor(file)
	return FormatNode(fset, n)
	}

	// findFileInDeps finds package metadata containing URI in the transitive
	// dependencies of m. When using the Go command, the answer is unique.
	func findFileInDeps(s metadata.Source, mp metadata.Package, uri protocol.DocumentURI) metadata.Package {
	seen := make(map[PackageID]bool)
	var search func(metadata.Package) metadata.Package
	search = func(mp metadata.Package) metadata.Package {
	if seen[mp.ID] {
	return nil
	}
	seen[mp.ID] = true
	for _, cgf := range mp.CompiledGoFiles {
	if cgf == uri {
	return mp
	}
	}
	for _, dep := range mp.DepsByPkgPath {
	mp := s.Metadata(dep)
	if mp == nil {
	bug.Reportf("nil metadata for %q", dep)
	continue
	}
	if found := search(mp); found != nil {
	return found
	}
	}
	return nil
	}
	return search(mp)
	}

	// CollectScopes returns all scopes in an ast path, ordered as innermost scope
	// first.
	func CollectScopes(info types.Info, path []ast.Node, pos token.Pos) []types.Scope {
	// scopes[i], where i<len(path), is the possibly nil Scope of path[i].
	var scopes []*types.Scope
	for _, n := range path {
	// Include *FuncType scope if pos is inside the function body.
	switch node := n.(type) {
	case *ast.FuncDecl:
	if node.Body != nil && astutil.NodeContains(node.Body, pos) {
	n = node.Type
	}
	case *ast.FuncLit:
	if node.Body != nil && astutil.NodeContains(node.Body, pos) {
	n = node.Type
	}
	}
	scopes = append(scopes, info.Scopes[n])
	}
	return scopes
	}

	// requalifier returns a function that re-qualifies identifiers and qualified
	// identifiers contained in targetFile using the given metadata qualifier.
	func requalifier(s metadata.Source, targetFile ast.File, targetMeta metadata.Package, mq MetadataQualifier) func(string) string {
	qm := map[string]string{
	"": mq(targetMeta.Name, "", targetMeta.PkgPath),
	}

	// Construct mapping of import paths to their defined or implicit names.
	for _, imp := range targetFile.Imports {
	name, pkgName, impPath, pkgPath := importInfo(s, imp, targetMeta)

	// Re-map the target name for the source file.
	qm[name] = mq(pkgName, impPath, pkgPath)
	}

	return func(name string) string {
	if newName, ok := qm[name]; ok {
	return newName
	}
	return name
	}
	}

	// A MetadataQualifier is a function that qualifies an identifier declared in a
	// package with the given package name, import path, and package path.
	//
	// In scenarios where metadata is missing the provided PackageName and
	// PackagePath may be empty, but ImportPath must always be non-empty.
	type MetadataQualifier func(PackageName, ImportPath, PackagePath) string

	// MetadataQualifierForFile returns a metadata qualifier that chooses the best
	// qualification of an imported package relative to the file f in package with
	// metadata m.
	func MetadataQualifierForFile(s metadata.Source, f ast.File, mp metadata.Package) MetadataQualifier {
	// Record local names for import paths.
	localNames := make(map[ImportPath]string) // local names for imports in f
	for _, imp := range f.Imports {
	name, _, impPath, _ := importInfo(s, imp, mp)
	localNames[impPath] = name
	}

	// Record a package path -> import path mapping.
	inverseDeps := make(map[PackageID]PackagePath)
	for path, id := range mp.DepsByPkgPath {
	inverseDeps[id] = path
	}
	importsByPkgPath := make(map[PackagePath]ImportPath) // best import paths by pkgPath
	for impPath, id := range mp.DepsByImpPath {
	if id == "" {
	continue
	}
	pkgPath := inverseDeps[id]
	_, hasPath := importsByPkgPath[pkgPath]
	_, hasImp := localNames[impPath]
	// In rare cases, there may be multiple import paths with the same package
	// path. In such scenarios, prefer an import path that already exists in
	// the file.
	if !hasPath \|\| hasImp {
	importsByPkgPath[pkgPath] = impPath
	}
	}

	return func(pkgName PackageName, impPath ImportPath, pkgPath PackagePath) string {
	// If supplied, translate the package path to an import path in the source
	// package.
	if pkgPath != "" {
	if srcImp := importsByPkgPath[pkgPath]; srcImp != "" {
	impPath = srcImp
	}
	if pkgPath == mp.PkgPath {
	return ""
	}
	}
	if localName, ok := localNames[impPath]; ok && impPath != "" {
	return localName
	}
	if pkgName != "" {
	return string(pkgName)
	}
	idx := strings.LastIndexByte(string(impPath), '/')
	return string(impPath[idx+1:])
	}
	}

	// importInfo collects information about the import specified by imp,
	// extracting its file-local name, package name, import path, and package path.
	//
	// If metadata is missing for the import, the resulting package name and
	// package path may be empty, and the file local name may be guessed based on
	// the import path.
	//
	// Note: previous versions of this helper used a PackageID->PackagePath map
	// extracted from m, for extracting package path even in the case where
	// metadata for a dep was missing. This should not be necessary, as we should
	// always have metadata for IDs contained in DepsByPkgPath.
	func importInfo(s metadata.Source, imp ast.ImportSpec, mp metadata.Package) (string, PackageName, ImportPath, PackagePath) {
	var (
	name string // local name
	pkgName PackageName
	impPath = metadata.UnquoteImportPath(imp)
	pkgPath PackagePath
	)

	// If the import has a local name, use it.
	if imp.Name != nil {
	name = imp.Name.Name
	}

	// Try to find metadata for the import. If successful and there is no local
	// name, the package name is the local name.
	if depID := mp.DepsByImpPath[impPath]; depID != "" {
	if depMP := s.Metadata(depID); depMP != nil {
	if name == "" {
	name = string(depMP.Name)
	}
	pkgName = depMP.Name
	pkgPath = depMP.PkgPath
	}
	}

	// If the local name is still unknown, guess it based on the import path.
	if name == "" {
	idx := strings.LastIndexByte(string(impPath), '/')
	name = string(impPath[idx+1:])
	}
	return name, pkgName, impPath, pkgPath
	}

	// isDirective reports whether c is a comment directive.
	//
	// Copied and adapted from go/src/go/ast/ast.go.
	func isDirective(c string) bool {
	if len(c) < 3 {
	return false
	}
	if c[1] != '/' {
	return false
	}
	//-style comment (no newline at the end)
	c = c[2:]
	if len(c) == 0 {
	// empty line
	return false
	}
	// "//line " is a line directive.
	// (The // has been removed.)
	if strings.HasPrefix(c, "line ") {
	return true
	}

	// "//[a-z0-9]+:[a-z0-9]"
	// (The // has been removed.)
	colon := strings.Index(c, ":")
	if colon <= 0 \|\| colon+1 >= len(c) {
	return false
	}
	for i := 0; i <= colon+1; i++ {
	if i == colon {
	continue
	}
	b := c[i]
	if !('a' <= b && b <= 'z' \|\| '0' <= b && b <= '9') {
	return false
	}
	}
	return true
	}

	// embeddedIdent returns the type name identifier for an embedding x, if x in a
	// valid embedding. Otherwise, it returns nil.
	//
	// Spec: An embedded field must be specified as a type name T or as a pointer
	// to a non-interface type name *T
	func embeddedIdent(x ast.Expr) *ast.Ident {
	if star, ok := x.(*ast.StarExpr); ok {
	x = star.X
	}
	switch ix := x.(type) { // check for instantiated receivers
	case *ast.IndexExpr:
	x = ix.X
	case *ast.IndexListExpr:
	x = ix.X
	}
	switch x := x.(type) {
	case *ast.Ident:
	return x
	case *ast.SelectorExpr:
	if _, ok := x.X.(*ast.Ident); ok {
	return x.Sel
	}
	}
	return nil
	}

	// An importFunc is an implementation of the single-method
	// types.Importer interface based on a function value.
	type ImporterFunc func(path string) (*types.Package, error)

	func (f ImporterFunc) Import(path string) (*types.Package, error) { return f(path) }