mvpkg.go

Documentation: golang.org/x/tools/refactor/rename

     1  // Copyright 2015 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // This file contains the implementation of the 'gomvpkg' command
     6  // whose main function is in golang.org/x/tools/cmd/gomvpkg.
     7  
     8  package rename
     9  
    10  // TODO(matloob):
    11  // - think about what happens if the package is moving across version control systems.
    12  // - dot imports are not supported. Make sure it's clearly documented.
    13  
    14  import (
    15  	"bytes"
    16  	"fmt"
    17  	"go/ast"
    18  	"go/build"
    19  	"go/format"
    20  	"go/token"
    21  	exec "golang.org/x/sys/execabs"
    22  	"log"
    23  	"os"
    24  	"path"
    25  	"path/filepath"
    26  	"regexp"
    27  	"runtime"
    28  	"strconv"
    29  	"strings"
    30  	"text/template"
    31  
    32  	"golang.org/x/tools/go/buildutil"
    33  	"golang.org/x/tools/go/loader"
    34  	"golang.org/x/tools/refactor/importgraph"
    35  )
    36  
    37  // Move, given a package path and a destination package path, will try
    38  // to move the given package to the new path. The Move function will
    39  // first check for any conflicts preventing the move, such as a
    40  // package already existing at the destination package path. If the
    41  // move can proceed, it builds an import graph to find all imports of
    42  // the packages whose paths need to be renamed. This includes uses of
    43  // the subpackages of the package to be moved as those packages will
    44  // also need to be moved. It then renames all imports to point to the
    45  // new paths, and then moves the packages to their new paths.
    46  func Move(ctxt *build.Context, from, to, moveTmpl string) error {
    47  	srcDir, err := srcDir(ctxt, from)
    48  	if err != nil {
    49  		return err
    50  	}
    51  
    52  	// This should be the only place in the program that constructs
    53  	// file paths.
    54  	fromDir := buildutil.JoinPath(ctxt, srcDir, filepath.FromSlash(from))
    55  	toDir := buildutil.JoinPath(ctxt, srcDir, filepath.FromSlash(to))
    56  	toParent := filepath.Dir(toDir)
    57  	if !buildutil.IsDir(ctxt, toParent) {
    58  		return fmt.Errorf("parent directory does not exist for path %s", toDir)
    59  	}
    60  
    61  	// Build the import graph and figure out which packages to update.
    62  	_, rev, errors := importgraph.Build(ctxt)
    63  	if len(errors) > 0 {
    64  		// With a large GOPATH tree, errors are inevitable.
    65  		// Report them but proceed.
    66  		fmt.Fprintf(os.Stderr, "While scanning Go workspace:\n")
    67  		for path, err := range errors {
    68  			fmt.Fprintf(os.Stderr, "Package %q: %s.\n", path, err)
    69  		}
    70  	}
    71  
    72  	// Determine the affected packages---the set of packages whose import
    73  	// statements need updating.
    74  	affectedPackages := map[string]bool{from: true}
    75  	destinations := make(map[string]string) // maps old import path to new import path
    76  	for pkg := range subpackages(ctxt, srcDir, from) {
    77  		for r := range rev[pkg] {
    78  			affectedPackages[r] = true
    79  		}
    80  		destinations[pkg] = strings.Replace(pkg, from, to, 1)
    81  	}
    82  
    83  	// Load all the affected packages.
    84  	iprog, err := loadProgram(ctxt, affectedPackages)
    85  	if err != nil {
    86  		return err
    87  	}
    88  
    89  	// Prepare the move command, if one was supplied.
    90  	var cmd string
    91  	if moveTmpl != "" {
    92  		if cmd, err = moveCmd(moveTmpl, fromDir, toDir); err != nil {
    93  			return err
    94  		}
    95  	}
    96  
    97  	m := mover{
    98  		ctxt:             ctxt,
    99  		rev:              rev,
   100  		iprog:            iprog,
   101  		from:             from,
   102  		to:               to,
   103  		fromDir:          fromDir,
   104  		toDir:            toDir,
   105  		affectedPackages: affectedPackages,
   106  		destinations:     destinations,
   107  		cmd:              cmd,
   108  	}
   109  
   110  	if err := m.checkValid(); err != nil {
   111  		return err
   112  	}
   113  
   114  	m.move()
   115  
   116  	return nil
   117  }
   118  
   119  // srcDir returns the absolute path of the srcdir containing pkg.
   120  func srcDir(ctxt *build.Context, pkg string) (string, error) {
   121  	for _, srcDir := range ctxt.SrcDirs() {
   122  		path := buildutil.JoinPath(ctxt, srcDir, pkg)
   123  		if buildutil.IsDir(ctxt, path) {
   124  			return srcDir, nil
   125  		}
   126  	}
   127  	return "", fmt.Errorf("src dir not found for package: %s", pkg)
   128  }
   129  
   130  // subpackages returns the set of packages in the given srcDir whose
   131  // import path equals to root, or has "root/" as the prefix.
   132  func subpackages(ctxt *build.Context, srcDir string, root string) map[string]bool {
   133  	var subs = make(map[string]bool)
   134  	buildutil.ForEachPackage(ctxt, func(pkg string, err error) {
   135  		if err != nil {
   136  			log.Fatalf("unexpected error in ForEachPackage: %v", err)
   137  		}
   138  
   139  		// Only process the package root, or a sub-package of it.
   140  		if !(strings.HasPrefix(pkg, root) &&
   141  			(len(pkg) == len(root) || pkg[len(root)] == '/')) {
   142  			return
   143  		}
   144  
   145  		p, err := ctxt.Import(pkg, "", build.FindOnly)
   146  		if err != nil {
   147  			log.Fatalf("unexpected: package %s can not be located by build context: %s", pkg, err)
   148  		}
   149  		if p.SrcRoot == "" {
   150  			log.Fatalf("unexpected: could not determine srcDir for package %s: %s", pkg, err)
   151  		}
   152  		if p.SrcRoot != srcDir {
   153  			return
   154  		}
   155  
   156  		subs[pkg] = true
   157  	})
   158  	return subs
   159  }
   160  
   161  type mover struct {
   162  	// iprog contains all packages whose contents need to be updated
   163  	// with new package names or import paths.
   164  	iprog *loader.Program
   165  	ctxt  *build.Context
   166  	// rev is the reverse import graph.
   167  	rev importgraph.Graph
   168  	// from and to are the source and destination import
   169  	// paths. fromDir and toDir are the source and destination
   170  	// absolute paths that package source files will be moved between.
   171  	from, to, fromDir, toDir string
   172  	// affectedPackages is the set of all packages whose contents need
   173  	// to be updated to reflect new package names or import paths.
   174  	affectedPackages map[string]bool
   175  	// destinations maps each subpackage to be moved to its
   176  	// destination path.
   177  	destinations map[string]string
   178  	// cmd, if not empty, will be executed to move fromDir to toDir.
   179  	cmd string
   180  }
   181  
   182  func (m *mover) checkValid() error {
   183  	const prefix = "invalid move destination"
   184  
   185  	match, err := regexp.MatchString("^[_\\pL][_\\pL\\p{Nd}]*$", path.Base(m.to))
   186  	if err != nil {
   187  		panic("regexp.MatchString failed")
   188  	}
   189  	if !match {
   190  		return fmt.Errorf("%s: %s; gomvpkg does not support move destinations "+
   191  			"whose base names are not valid go identifiers", prefix, m.to)
   192  	}
   193  
   194  	if buildutil.FileExists(m.ctxt, m.toDir) {
   195  		return fmt.Errorf("%s: %s conflicts with file %s", prefix, m.to, m.toDir)
   196  	}
   197  	if buildutil.IsDir(m.ctxt, m.toDir) {
   198  		return fmt.Errorf("%s: %s conflicts with directory %s", prefix, m.to, m.toDir)
   199  	}
   200  
   201  	for _, toSubPkg := range m.destinations {
   202  		if _, err := m.ctxt.Import(toSubPkg, "", build.FindOnly); err == nil {
   203  			return fmt.Errorf("%s: %s; package or subpackage %s already exists",
   204  				prefix, m.to, toSubPkg)
   205  		}
   206  	}
   207  
   208  	return nil
   209  }
   210  
   211  // moveCmd produces the version control move command used to move fromDir to toDir by
   212  // executing the given template.
   213  func moveCmd(moveTmpl, fromDir, toDir string) (string, error) {
   214  	tmpl, err := template.New("movecmd").Parse(moveTmpl)
   215  	if err != nil {
   216  		return "", err
   217  	}
   218  
   219  	var buf bytes.Buffer
   220  	err = tmpl.Execute(&buf, struct {
   221  		Src string
   222  		Dst string
   223  	}{fromDir, toDir})
   224  	return buf.String(), err
   225  }
   226  
   227  func (m *mover) move() error {
   228  	filesToUpdate := make(map[*ast.File]bool)
   229  
   230  	// Change the moved package's "package" declaration to its new base name.
   231  	pkg, ok := m.iprog.Imported[m.from]
   232  	if !ok {
   233  		log.Fatalf("unexpected: package %s is not in import map", m.from)
   234  	}
   235  	newName := filepath.Base(m.to)
   236  	for _, f := range pkg.Files {
   237  		// Update all import comments.
   238  		for _, cg := range f.Comments {
   239  			c := cg.List[0]
   240  			if c.Slash >= f.Name.End() &&
   241  				sameLine(m.iprog.Fset, c.Slash, f.Name.End()) &&
   242  				(f.Decls == nil || c.Slash < f.Decls[0].Pos()) {
   243  				if strings.HasPrefix(c.Text, `// import "`) {
   244  					c.Text = `// import "` + m.to + `"`
   245  					break
   246  				}
   247  				if strings.HasPrefix(c.Text, `/* import "`) {
   248  					c.Text = `/* import "` + m.to + `" */`
   249  					break
   250  				}
   251  			}
   252  		}
   253  		f.Name.Name = newName // change package decl
   254  		filesToUpdate[f] = true
   255  	}
   256  
   257  	// Look through the external test packages (m.iprog.Created contains the external test packages).
   258  	for _, info := range m.iprog.Created {
   259  		// Change the "package" declaration of the external test package.
   260  		if info.Pkg.Path() == m.from+"_test" {
   261  			for _, f := range info.Files {
   262  				f.Name.Name = newName + "_test" // change package decl
   263  				filesToUpdate[f] = true
   264  			}
   265  		}
   266  
   267  		// Mark all the loaded external test packages, which import the "from" package,
   268  		// as affected packages and update the imports.
   269  		for _, imp := range info.Pkg.Imports() {
   270  			if imp.Path() == m.from {
   271  				m.affectedPackages[info.Pkg.Path()] = true
   272  				m.iprog.Imported[info.Pkg.Path()] = info
   273  				if err := importName(m.iprog, info, m.from, path.Base(m.from), newName); err != nil {
   274  					return err
   275  				}
   276  			}
   277  		}
   278  	}
   279  
   280  	// Update imports of that package to use the new import name.
   281  	// None of the subpackages will change their name---only the from package
   282  	// itself will.
   283  	for p := range m.rev[m.from] {
   284  		if err := importName(m.iprog, m.iprog.Imported[p], m.from, path.Base(m.from), newName); err != nil {
   285  			return err
   286  		}
   287  	}
   288  
   289  	// Update import paths for all imports by affected packages.
   290  	for ap := range m.affectedPackages {
   291  		info, ok := m.iprog.Imported[ap]
   292  		if !ok {
   293  			log.Fatalf("unexpected: package %s is not in import map", ap)
   294  		}
   295  		for _, f := range info.Files {
   296  			for _, imp := range f.Imports {
   297  				importPath, _ := strconv.Unquote(imp.Path.Value)
   298  				if newPath, ok := m.destinations[importPath]; ok {
   299  					imp.Path.Value = strconv.Quote(newPath)
   300  
   301  					oldName := path.Base(importPath)
   302  					if imp.Name != nil {
   303  						oldName = imp.Name.Name
   304  					}
   305  
   306  					newName := path.Base(newPath)
   307  					if imp.Name == nil && oldName != newName {
   308  						imp.Name = ast.NewIdent(oldName)
   309  					} else if imp.Name == nil || imp.Name.Name == newName {
   310  						imp.Name = nil
   311  					}
   312  					filesToUpdate[f] = true
   313  				}
   314  			}
   315  		}
   316  	}
   317  
   318  	for f := range filesToUpdate {
   319  		var buf bytes.Buffer
   320  		if err := format.Node(&buf, m.iprog.Fset, f); err != nil {
   321  			log.Printf("failed to pretty-print syntax tree: %v", err)
   322  			continue
   323  		}
   324  		tokenFile := m.iprog.Fset.File(f.Pos())
   325  		writeFile(tokenFile.Name(), buf.Bytes())
   326  	}
   327  
   328  	// Move the directories.
   329  	// If either the fromDir or toDir are contained under version control it is
   330  	// the user's responsibility to provide a custom move command that updates
   331  	// version control to reflect the move.
   332  	// TODO(matloob): If the parent directory of toDir does not exist, create it.
   333  	//      For now, it's required that it does exist.
   334  
   335  	if m.cmd != "" {
   336  		// TODO(matloob): Verify that the windows and plan9 cases are correct.
   337  		var cmd *exec.Cmd
   338  		switch runtime.GOOS {
   339  		case "windows":
   340  			cmd = exec.Command("cmd", "/c", m.cmd)
   341  		case "plan9":
   342  			cmd = exec.Command("rc", "-c", m.cmd)
   343  		default:
   344  			cmd = exec.Command("sh", "-c", m.cmd)
   345  		}
   346  		cmd.Stderr = os.Stderr
   347  		cmd.Stdout = os.Stdout
   348  		if err := cmd.Run(); err != nil {
   349  			return fmt.Errorf("version control system's move command failed: %v", err)
   350  		}
   351  
   352  		return nil
   353  	}
   354  
   355  	return moveDirectory(m.fromDir, m.toDir)
   356  }
   357  
   358  // sameLine reports whether two positions in the same file are on the same line.
   359  func sameLine(fset *token.FileSet, x, y token.Pos) bool {
   360  	return fset.Position(x).Line == fset.Position(y).Line
   361  }
   362  
   363  var moveDirectory = func(from, to string) error {
   364  	return os.Rename(from, to)
   365  }
   366
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