+++ /dev/null
-// Copyright 2013 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 astutil contains common utilities for working with the Go AST.
-package astutil // import "golang.org/x/tools/go/ast/astutil"
-
-import (
- "fmt"
- "go/ast"
- "go/token"
- "strconv"
- "strings"
-)
-
-// AddImport adds the import path to the file f, if absent.
-func AddImport(fset *token.FileSet, f *ast.File, path string) (added bool) {
- return AddNamedImport(fset, f, "", path)
-}
-
-// AddNamedImport adds the import with the given name and path to the file f, if absent.
-// If name is not empty, it is used to rename the import.
-//
-// For example, calling
-// AddNamedImport(fset, f, "pathpkg", "path")
-// adds
-// import pathpkg "path"
-func AddNamedImport(fset *token.FileSet, f *ast.File, name, path string) (added bool) {
- if imports(f, name, path) {
- return false
- }
-
- newImport := &ast.ImportSpec{
- Path: &ast.BasicLit{
- Kind: token.STRING,
- Value: strconv.Quote(path),
- },
- }
- if name != "" {
- newImport.Name = &ast.Ident{Name: name}
- }
-
- // Find an import decl to add to.
- // The goal is to find an existing import
- // whose import path has the longest shared
- // prefix with path.
- var (
- bestMatch = -1 // length of longest shared prefix
- lastImport = -1 // index in f.Decls of the file's final import decl
- impDecl *ast.GenDecl // import decl containing the best match
- impIndex = -1 // spec index in impDecl containing the best match
-
- isThirdPartyPath = isThirdParty(path)
- )
- for i, decl := range f.Decls {
- gen, ok := decl.(*ast.GenDecl)
- if ok && gen.Tok == token.IMPORT {
- lastImport = i
- // Do not add to import "C", to avoid disrupting the
- // association with its doc comment, breaking cgo.
- if declImports(gen, "C") {
- continue
- }
-
- // Match an empty import decl if that's all that is available.
- if len(gen.Specs) == 0 && bestMatch == -1 {
- impDecl = gen
- }
-
- // Compute longest shared prefix with imports in this group and find best
- // matched import spec.
- // 1. Always prefer import spec with longest shared prefix.
- // 2. While match length is 0,
- // - for stdlib package: prefer first import spec.
- // - for third party package: prefer first third party import spec.
- // We cannot use last import spec as best match for third party package
- // because grouped imports are usually placed last by goimports -local
- // flag.
- // See issue #19190.
- seenAnyThirdParty := false
- for j, spec := range gen.Specs {
- impspec := spec.(*ast.ImportSpec)
- p := importPath(impspec)
- n := matchLen(p, path)
- if n > bestMatch || (bestMatch == 0 && !seenAnyThirdParty && isThirdPartyPath) {
- bestMatch = n
- impDecl = gen
- impIndex = j
- }
- seenAnyThirdParty = seenAnyThirdParty || isThirdParty(p)
- }
- }
- }
-
- // If no import decl found, add one after the last import.
- if impDecl == nil {
- impDecl = &ast.GenDecl{
- Tok: token.IMPORT,
- }
- if lastImport >= 0 {
- impDecl.TokPos = f.Decls[lastImport].End()
- } else {
- // There are no existing imports.
- // Our new import, preceded by a blank line, goes after the package declaration
- // and after the comment, if any, that starts on the same line as the
- // package declaration.
- impDecl.TokPos = f.Package
-
- file := fset.File(f.Package)
- pkgLine := file.Line(f.Package)
- for _, c := range f.Comments {
- if file.Line(c.Pos()) > pkgLine {
- break
- }
- // +2 for a blank line
- impDecl.TokPos = c.End() + 2
- }
- }
- f.Decls = append(f.Decls, nil)
- copy(f.Decls[lastImport+2:], f.Decls[lastImport+1:])
- f.Decls[lastImport+1] = impDecl
- }
-
- // Insert new import at insertAt.
- insertAt := 0
- if impIndex >= 0 {
- // insert after the found import
- insertAt = impIndex + 1
- }
- impDecl.Specs = append(impDecl.Specs, nil)
- copy(impDecl.Specs[insertAt+1:], impDecl.Specs[insertAt:])
- impDecl.Specs[insertAt] = newImport
- pos := impDecl.Pos()
- if insertAt > 0 {
- // If there is a comment after an existing import, preserve the comment
- // position by adding the new import after the comment.
- if spec, ok := impDecl.Specs[insertAt-1].(*ast.ImportSpec); ok && spec.Comment != nil {
- pos = spec.Comment.End()
- } else {
- // Assign same position as the previous import,
- // so that the sorter sees it as being in the same block.
- pos = impDecl.Specs[insertAt-1].Pos()
- }
- }
- if newImport.Name != nil {
- newImport.Name.NamePos = pos
- }
- newImport.Path.ValuePos = pos
- newImport.EndPos = pos
-
- // Clean up parens. impDecl contains at least one spec.
- if len(impDecl.Specs) == 1 {
- // Remove unneeded parens.
- impDecl.Lparen = token.NoPos
- } else if !impDecl.Lparen.IsValid() {
- // impDecl needs parens added.
- impDecl.Lparen = impDecl.Specs[0].Pos()
- }
-
- f.Imports = append(f.Imports, newImport)
-
- if len(f.Decls) <= 1 {
- return true
- }
-
- // Merge all the import declarations into the first one.
- var first *ast.GenDecl
- for i := 0; i < len(f.Decls); i++ {
- decl := f.Decls[i]
- gen, ok := decl.(*ast.GenDecl)
- if !ok || gen.Tok != token.IMPORT || declImports(gen, "C") {
- continue
- }
- if first == nil {
- first = gen
- continue // Don't touch the first one.
- }
- // We now know there is more than one package in this import
- // declaration. Ensure that it ends up parenthesized.
- first.Lparen = first.Pos()
- // Move the imports of the other import declaration to the first one.
- for _, spec := range gen.Specs {
- spec.(*ast.ImportSpec).Path.ValuePos = first.Pos()
- first.Specs = append(first.Specs, spec)
- }
- f.Decls = append(f.Decls[:i], f.Decls[i+1:]...)
- i--
- }
-
- return true
-}
-
-func isThirdParty(importPath string) bool {
- // Third party package import path usually contains "." (".com", ".org", ...)
- // This logic is taken from golang.org/x/tools/imports package.
- return strings.Contains(importPath, ".")
-}
-
-// DeleteImport deletes the import path from the file f, if present.
-// If there are duplicate import declarations, all matching ones are deleted.
-func DeleteImport(fset *token.FileSet, f *ast.File, path string) (deleted bool) {
- return DeleteNamedImport(fset, f, "", path)
-}
-
-// DeleteNamedImport deletes the import with the given name and path from the file f, if present.
-// If there are duplicate import declarations, all matching ones are deleted.
-func DeleteNamedImport(fset *token.FileSet, f *ast.File, name, path string) (deleted bool) {
- var delspecs []*ast.ImportSpec
- var delcomments []*ast.CommentGroup
-
- // Find the import nodes that import path, if any.
- for i := 0; i < len(f.Decls); i++ {
- decl := f.Decls[i]
- gen, ok := decl.(*ast.GenDecl)
- if !ok || gen.Tok != token.IMPORT {
- continue
- }
- for j := 0; j < len(gen.Specs); j++ {
- spec := gen.Specs[j]
- impspec := spec.(*ast.ImportSpec)
- if importName(impspec) != name || importPath(impspec) != path {
- continue
- }
-
- // We found an import spec that imports path.
- // Delete it.
- delspecs = append(delspecs, impspec)
- deleted = true
- copy(gen.Specs[j:], gen.Specs[j+1:])
- gen.Specs = gen.Specs[:len(gen.Specs)-1]
-
- // If this was the last import spec in this decl,
- // delete the decl, too.
- if len(gen.Specs) == 0 {
- copy(f.Decls[i:], f.Decls[i+1:])
- f.Decls = f.Decls[:len(f.Decls)-1]
- i--
- break
- } else if len(gen.Specs) == 1 {
- if impspec.Doc != nil {
- delcomments = append(delcomments, impspec.Doc)
- }
- if impspec.Comment != nil {
- delcomments = append(delcomments, impspec.Comment)
- }
- for _, cg := range f.Comments {
- // Found comment on the same line as the import spec.
- if cg.End() < impspec.Pos() && fset.Position(cg.End()).Line == fset.Position(impspec.Pos()).Line {
- delcomments = append(delcomments, cg)
- break
- }
- }
-
- spec := gen.Specs[0].(*ast.ImportSpec)
-
- // Move the documentation right after the import decl.
- if spec.Doc != nil {
- for fset.Position(gen.TokPos).Line+1 < fset.Position(spec.Doc.Pos()).Line {
- fset.File(gen.TokPos).MergeLine(fset.Position(gen.TokPos).Line)
- }
- }
- for _, cg := range f.Comments {
- if cg.End() < spec.Pos() && fset.Position(cg.End()).Line == fset.Position(spec.Pos()).Line {
- for fset.Position(gen.TokPos).Line+1 < fset.Position(spec.Pos()).Line {
- fset.File(gen.TokPos).MergeLine(fset.Position(gen.TokPos).Line)
- }
- break
- }
- }
- }
- if j > 0 {
- lastImpspec := gen.Specs[j-1].(*ast.ImportSpec)
- lastLine := fset.Position(lastImpspec.Path.ValuePos).Line
- line := fset.Position(impspec.Path.ValuePos).Line
-
- // We deleted an entry but now there may be
- // a blank line-sized hole where the import was.
- if line-lastLine > 1 || !gen.Rparen.IsValid() {
- // There was a blank line immediately preceding the deleted import,
- // so there's no need to close the hole. The right parenthesis is
- // invalid after AddImport to an import statement without parenthesis.
- // Do nothing.
- } else if line != fset.File(gen.Rparen).LineCount() {
- // There was no blank line. Close the hole.
- fset.File(gen.Rparen).MergeLine(line)
- }
- }
- j--
- }
- }
-
- // Delete imports from f.Imports.
- for i := 0; i < len(f.Imports); i++ {
- imp := f.Imports[i]
- for j, del := range delspecs {
- if imp == del {
- copy(f.Imports[i:], f.Imports[i+1:])
- f.Imports = f.Imports[:len(f.Imports)-1]
- copy(delspecs[j:], delspecs[j+1:])
- delspecs = delspecs[:len(delspecs)-1]
- i--
- break
- }
- }
- }
-
- // Delete comments from f.Comments.
- for i := 0; i < len(f.Comments); i++ {
- cg := f.Comments[i]
- for j, del := range delcomments {
- if cg == del {
- copy(f.Comments[i:], f.Comments[i+1:])
- f.Comments = f.Comments[:len(f.Comments)-1]
- copy(delcomments[j:], delcomments[j+1:])
- delcomments = delcomments[:len(delcomments)-1]
- i--
- break
- }
- }
- }
-
- if len(delspecs) > 0 {
- panic(fmt.Sprintf("deleted specs from Decls but not Imports: %v", delspecs))
- }
-
- return
-}
-
-// RewriteImport rewrites any import of path oldPath to path newPath.
-func RewriteImport(fset *token.FileSet, f *ast.File, oldPath, newPath string) (rewrote bool) {
- for _, imp := range f.Imports {
- if importPath(imp) == oldPath {
- rewrote = true
- // record old End, because the default is to compute
- // it using the length of imp.Path.Value.
- imp.EndPos = imp.End()
- imp.Path.Value = strconv.Quote(newPath)
- }
- }
- return
-}
-
-// UsesImport reports whether a given import is used.
-func UsesImport(f *ast.File, path string) (used bool) {
- spec := importSpec(f, path)
- if spec == nil {
- return
- }
-
- name := spec.Name.String()
- switch name {
- case "<nil>":
- // If the package name is not explicitly specified,
- // make an educated guess. This is not guaranteed to be correct.
- lastSlash := strings.LastIndex(path, "/")
- if lastSlash == -1 {
- name = path
- } else {
- name = path[lastSlash+1:]
- }
- case "_", ".":
- // Not sure if this import is used - err on the side of caution.
- return true
- }
-
- ast.Walk(visitFn(func(n ast.Node) {
- sel, ok := n.(*ast.SelectorExpr)
- if ok && isTopName(sel.X, name) {
- used = true
- }
- }), f)
-
- return
-}
-
-type visitFn func(node ast.Node)
-
-func (fn visitFn) Visit(node ast.Node) ast.Visitor {
- fn(node)
- return fn
-}
-
-// imports reports whether f has an import with the specified name and path.
-func imports(f *ast.File, name, path string) bool {
- for _, s := range f.Imports {
- if importName(s) == name && importPath(s) == path {
- return true
- }
- }
- return false
-}
-
-// importSpec returns the import spec if f imports path,
-// or nil otherwise.
-func importSpec(f *ast.File, path string) *ast.ImportSpec {
- for _, s := range f.Imports {
- if importPath(s) == path {
- return s
- }
- }
- return nil
-}
-
-// importName returns the name of s,
-// or "" if the import is not named.
-func importName(s *ast.ImportSpec) string {
- if s.Name == nil {
- return ""
- }
- return s.Name.Name
-}
-
-// importPath returns the unquoted import path of s,
-// or "" if the path is not properly quoted.
-func importPath(s *ast.ImportSpec) string {
- t, err := strconv.Unquote(s.Path.Value)
- if err != nil {
- return ""
- }
- return t
-}
-
-// declImports reports whether gen contains an import of path.
-func declImports(gen *ast.GenDecl, path string) bool {
- if gen.Tok != token.IMPORT {
- return false
- }
- for _, spec := range gen.Specs {
- impspec := spec.(*ast.ImportSpec)
- if importPath(impspec) == path {
- return true
- }
- }
- return false
-}
-
-// matchLen returns the length of the longest path segment prefix shared by x and y.
-func matchLen(x, y string) int {
- n := 0
- for i := 0; i < len(x) && i < len(y) && x[i] == y[i]; i++ {
- if x[i] == '/' {
- n++
- }
- }
- return n
-}
-
-// isTopName returns true if n is a top-level unresolved identifier with the given name.
-func isTopName(n ast.Expr, name string) bool {
- id, ok := n.(*ast.Ident)
- return ok && id.Name == name && id.Obj == nil
-}
-
-// Imports returns the file imports grouped by paragraph.
-func Imports(fset *token.FileSet, f *ast.File) [][]*ast.ImportSpec {
- var groups [][]*ast.ImportSpec
-
- for _, decl := range f.Decls {
- genDecl, ok := decl.(*ast.GenDecl)
- if !ok || genDecl.Tok != token.IMPORT {
- break
- }
-
- group := []*ast.ImportSpec{}
-
- var lastLine int
- for _, spec := range genDecl.Specs {
- importSpec := spec.(*ast.ImportSpec)
- pos := importSpec.Path.ValuePos
- line := fset.Position(pos).Line
- if lastLine > 0 && pos > 0 && line-lastLine > 1 {
- groups = append(groups, group)
- group = []*ast.ImportSpec{}
- }
- group = append(group, importSpec)
- lastLine = line
- }
- groups = append(groups, group)
- }
-
- return groups
-}
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