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// Copyright 2015 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.
// This file contains the implementation of the 'gomvpkg' command
// whose main function is in golang.org/x/tools/cmd/gomvpkg.
package rename
// TODO(matloob):
// - think about what happens if the package is moving across version control systems.
// - dot imports are not supported. Make sure it's clearly documented.
import (
"bytes"
"fmt"
"go/ast"
"go/build"
"go/format"
"go/token"
"log"
"os"
"os/exec"
"path"
"path/filepath"
"regexp"
"runtime"
"strconv"
"strings"
"text/template"
"golang.org/x/tools/go/buildutil"
"golang.org/x/tools/go/loader"
"golang.org/x/tools/refactor/importgraph"
)
// Move, given a package path and a destination package path, will try
// to move the given package to the new path. The Move function will
// first check for any conflicts preventing the move, such as a
// package already existing at the destination package path. If the
// move can proceed, it builds an import graph to find all imports of
// the packages whose paths need to be renamed. This includes uses of
// the subpackages of the package to be moved as those packages will
// also need to be moved. It then renames all imports to point to the
// new paths, and then moves the packages to their new paths.
func Move(ctxt *build.Context, from, to, moveTmpl string) error {
srcDir, err := srcDir(ctxt, from)
if err != nil {
return err
}
// This should be the only place in the program that constructs
// file paths.
fromDir := buildutil.JoinPath(ctxt, srcDir, filepath.FromSlash(from))
toDir := buildutil.JoinPath(ctxt, srcDir, filepath.FromSlash(to))
toParent := filepath.Dir(toDir)
if !buildutil.IsDir(ctxt, toParent) {
return fmt.Errorf("parent directory does not exist for path %s", toDir)
}
// Build the import graph and figure out which packages to update.
_, rev, errors := importgraph.Build(ctxt)
if len(errors) > 0 {
// With a large GOPATH tree, errors are inevitable.
// Report them but proceed.
fmt.Fprintf(os.Stderr, "While scanning Go workspace:\n")
for path, err := range errors {
fmt.Fprintf(os.Stderr, "Package %q: %s.\n", path, err)
}
}
// Determine the affected packages---the set of packages whose import
// statements need updating.
affectedPackages := map[string]bool{from: true}
destinations := make(map[string]string) // maps old import path to new import path
for pkg := range subpackages(ctxt, srcDir, from) {
for r := range rev[pkg] {
affectedPackages[r] = true
}
destinations[pkg] = strings.Replace(pkg, from, to, 1)
}
// Load all the affected packages.
iprog, err := loadProgram(ctxt, affectedPackages)
if err != nil {
return err
}
// Prepare the move command, if one was supplied.
var cmd string
if moveTmpl != "" {
if cmd, err = moveCmd(moveTmpl, fromDir, toDir); err != nil {
return err
}
}
m := mover{
ctxt: ctxt,
rev: rev,
iprog: iprog,
from: from,
to: to,
fromDir: fromDir,
toDir: toDir,
affectedPackages: affectedPackages,
destinations: destinations,
cmd: cmd,
}
if err := m.checkValid(); err != nil {
return err
}
m.move()
return nil
}
// srcDir returns the absolute path of the srcdir containing pkg.
func srcDir(ctxt *build.Context, pkg string) (string, error) {
for _, srcDir := range ctxt.SrcDirs() {
path := buildutil.JoinPath(ctxt, srcDir, pkg)
if buildutil.IsDir(ctxt, path) {
return srcDir, nil
}
}
return "", fmt.Errorf("src dir not found for package: %s", pkg)
}
// subpackages returns the set of packages in the given srcDir whose
// import path equals to root, or has "root/" as the prefix.
func subpackages(ctxt *build.Context, srcDir string, root string) map[string]bool {
var subs = make(map[string]bool)
buildutil.ForEachPackage(ctxt, func(pkg string, err error) {
if err != nil {
log.Fatalf("unexpected error in ForEachPackage: %v", err)
}
// Only process the package root, or a sub-package of it.
if !(strings.HasPrefix(pkg, root) &&
(len(pkg) == len(root) || pkg[len(root)] == '/')) {
return
}
p, err := ctxt.Import(pkg, "", build.FindOnly)
if err != nil {
log.Fatalf("unexpected: package %s can not be located by build context: %s", pkg, err)
}
if p.SrcRoot == "" {
log.Fatalf("unexpected: could not determine srcDir for package %s: %s", pkg, err)
}
if p.SrcRoot != srcDir {
return
}
subs[pkg] = true
})
return subs
}
type mover struct {
// iprog contains all packages whose contents need to be updated
// with new package names or import paths.
iprog *loader.Program
ctxt *build.Context
// rev is the reverse import graph.
rev importgraph.Graph
// from and to are the source and destination import
// paths. fromDir and toDir are the source and destination
// absolute paths that package source files will be moved between.
from, to, fromDir, toDir string
// affectedPackages is the set of all packages whose contents need
// to be updated to reflect new package names or import paths.
affectedPackages map[string]bool
// destinations maps each subpackage to be moved to its
// destination path.
destinations map[string]string
// cmd, if not empty, will be executed to move fromDir to toDir.
cmd string
}
func (m *mover) checkValid() error {
const prefix = "invalid move destination"
match, err := regexp.MatchString("^[_\\pL][_\\pL\\p{Nd}]*$", path.Base(m.to))
if err != nil {
panic("regexp.MatchString failed")
}
if !match {
return fmt.Errorf("%s: %s; gomvpkg does not support move destinations "+
"whose base names are not valid go identifiers", prefix, m.to)
}
if buildutil.FileExists(m.ctxt, m.toDir) {
return fmt.Errorf("%s: %s conflicts with file %s", prefix, m.to, m.toDir)
}
if buildutil.IsDir(m.ctxt, m.toDir) {
return fmt.Errorf("%s: %s conflicts with directory %s", prefix, m.to, m.toDir)
}
for _, toSubPkg := range m.destinations {
if _, err := m.ctxt.Import(toSubPkg, "", build.FindOnly); err == nil {
return fmt.Errorf("%s: %s; package or subpackage %s already exists",
prefix, m.to, toSubPkg)
}
}
return nil
}
// moveCmd produces the version control move command used to move fromDir to toDir by
// executing the given template.
func moveCmd(moveTmpl, fromDir, toDir string) (string, error) {
tmpl, err := template.New("movecmd").Parse(moveTmpl)
if err != nil {
return "", err
}
var buf bytes.Buffer
err = tmpl.Execute(&buf, struct {
Src string
Dst string
}{fromDir, toDir})
return buf.String(), err
}
func (m *mover) move() error {
filesToUpdate := make(map[*ast.File]bool)
// Change the moved package's "package" declaration to its new base name.
pkg, ok := m.iprog.Imported[m.from]
if !ok {
log.Fatalf("unexpected: package %s is not in import map", m.from)
}
newName := filepath.Base(m.to)
for _, f := range pkg.Files {
// Update all import comments.
for _, cg := range f.Comments {
c := cg.List[0]
if c.Slash >= f.Name.End() &&
sameLine(m.iprog.Fset, c.Slash, f.Name.End()) &&
(f.Decls == nil || c.Slash < f.Decls[0].Pos()) {
if strings.HasPrefix(c.Text, `// import "`) {
c.Text = `// import "` + m.to + `"`
break
}
if strings.HasPrefix(c.Text, `/* import "`) {
c.Text = `/* import "` + m.to + `" */`
break
}
}
}
f.Name.Name = newName // change package decl
filesToUpdate[f] = true
}
// Look through the external test packages (m.iprog.Created contains the external test packages).
for _, info := range m.iprog.Created {
// Change the "package" declaration of the external test package.
if info.Pkg.Path() == m.from+"_test" {
for _, f := range info.Files {
f.Name.Name = newName + "_test" // change package decl
filesToUpdate[f] = true
}
}
// Mark all the loaded external test packages, which import the "from" package,
// as affected packages and update the imports.
for _, imp := range info.Pkg.Imports() {
if imp.Path() == m.from {
m.affectedPackages[info.Pkg.Path()] = true
m.iprog.Imported[info.Pkg.Path()] = info
if err := importName(m.iprog, info, m.from, path.Base(m.from), newName); err != nil {
return err
}
}
}
}
// Update imports of that package to use the new import name.
// None of the subpackages will change their name---only the from package
// itself will.
for p := range m.rev[m.from] {
if err := importName(m.iprog, m.iprog.Imported[p], m.from, path.Base(m.from), newName); err != nil {
return err
}
}
// Update import paths for all imports by affected packages.
for ap := range m.affectedPackages {
info, ok := m.iprog.Imported[ap]
if !ok {
log.Fatalf("unexpected: package %s is not in import map", ap)
}
for _, f := range info.Files {
for _, imp := range f.Imports {
importPath, _ := strconv.Unquote(imp.Path.Value)
if newPath, ok := m.destinations[importPath]; ok {
imp.Path.Value = strconv.Quote(newPath)
oldName := path.Base(importPath)
if imp.Name != nil {
oldName = imp.Name.Name
}
newName := path.Base(newPath)
if imp.Name == nil && oldName != newName {
imp.Name = ast.NewIdent(oldName)
} else if imp.Name == nil || imp.Name.Name == newName {
imp.Name = nil
}
filesToUpdate[f] = true
}
}
}
}
for f := range filesToUpdate {
var buf bytes.Buffer
if err := format.Node(&buf, m.iprog.Fset, f); err != nil {
log.Printf("failed to pretty-print syntax tree: %v", err)
continue
}
tokenFile := m.iprog.Fset.File(f.Pos())
writeFile(tokenFile.Name(), buf.Bytes())
}
// Move the directories.
// If either the fromDir or toDir are contained under version control it is
// the user's responsibility to provide a custom move command that updates
// version control to reflect the move.
// TODO(matloob): If the parent directory of toDir does not exist, create it.
// For now, it's required that it does exist.
if m.cmd != "" {
// TODO(matloob): Verify that the windows and plan9 cases are correct.
var cmd *exec.Cmd
switch runtime.GOOS {
case "windows":
cmd = exec.Command("cmd", "/c", m.cmd)
case "plan9":
cmd = exec.Command("rc", "-c", m.cmd)
default:
cmd = exec.Command("sh", "-c", m.cmd)
}
cmd.Stderr = os.Stderr
cmd.Stdout = os.Stdout
if err := cmd.Run(); err != nil {
return fmt.Errorf("version control system's move command failed: %v", err)
}
return nil
}
return moveDirectory(m.fromDir, m.toDir)
}
// sameLine reports whether two positions in the same file are on the same line.
func sameLine(fset *token.FileSet, x, y token.Pos) bool {
return fset.Position(x).Line == fset.Position(y).Line
}
var moveDirectory = func(from, to string) error {
return os.Rename(from, to)
}