1 | // Copyright 2014 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 | package rename |
6 | |
7 | // This file contains logic related to specifying a renaming: parsing of |
8 | // the flags as a form of query, and finding the object(s) it denotes. |
9 | // See Usage for flag details. |
10 | |
11 | import ( |
12 | "bytes" |
13 | "fmt" |
14 | "go/ast" |
15 | "go/build" |
16 | "go/parser" |
17 | "go/token" |
18 | "go/types" |
19 | "log" |
20 | "os" |
21 | "path/filepath" |
22 | "regexp" |
23 | "strconv" |
24 | "strings" |
25 | |
26 | "golang.org/x/tools/go/buildutil" |
27 | "golang.org/x/tools/go/loader" |
28 | ) |
29 | |
30 | // A spec specifies an entity to rename. |
31 | // |
32 | // It is populated from an -offset flag or -from query; |
33 | // see Usage for the allowed -from query forms. |
34 | type spec struct { |
35 | // pkg is the package containing the position |
36 | // specified by the -from or -offset flag. |
37 | // If filename == "", our search for the 'from' entity |
38 | // is restricted to this package. |
39 | pkg string |
40 | |
41 | // The original name of the entity being renamed. |
42 | // If the query had a ::from component, this is that; |
43 | // otherwise it's the last segment, e.g. |
44 | // (encoding/json.Decoder).from |
45 | // encoding/json.from |
46 | fromName string |
47 | |
48 | // -- The remaining fields are private to this file. All are optional. -- |
49 | |
50 | // The query's ::x suffix, if any. |
51 | searchFor string |
52 | |
53 | // e.g. "Decoder" in "(encoding/json.Decoder).fieldOrMethod" |
54 | // or "encoding/json.Decoder |
55 | pkgMember string |
56 | |
57 | // e.g. fieldOrMethod in "(encoding/json.Decoder).fieldOrMethod" |
58 | typeMember string |
59 | |
60 | // Restricts the query to this file. |
61 | // Implied by -from="file.go::x" and -offset flags. |
62 | filename string |
63 | |
64 | // Byte offset of the 'from' identifier within the file named 'filename'. |
65 | // -offset mode only. |
66 | offset int |
67 | } |
68 | |
69 | // parseFromFlag interprets the "-from" flag value as a renaming specification. |
70 | // See Usage in rename.go for valid formats. |
71 | func parseFromFlag(ctxt *build.Context, fromFlag string) (*spec, error) { |
72 | var spec spec |
73 | var main string // sans "::x" suffix |
74 | switch parts := strings.Split(fromFlag, "::"); len(parts) { |
75 | case 1: |
76 | main = parts[0] |
77 | case 2: |
78 | main = parts[0] |
79 | spec.searchFor = parts[1] |
80 | if parts[1] == "" { |
81 | // error |
82 | } |
83 | default: |
84 | return nil, fmt.Errorf("-from %q: invalid identifier specification (see -help for formats)", fromFlag) |
85 | } |
86 | |
87 | if strings.HasSuffix(main, ".go") { |
88 | // main is "filename.go" |
89 | if spec.searchFor == "" { |
90 | return nil, fmt.Errorf("-from: filename %q must have a ::name suffix", main) |
91 | } |
92 | spec.filename = main |
93 | if !buildutil.FileExists(ctxt, spec.filename) { |
94 | return nil, fmt.Errorf("no such file: %s", spec.filename) |
95 | } |
96 | |
97 | bp, err := buildutil.ContainingPackage(ctxt, wd, spec.filename) |
98 | if err != nil { |
99 | return nil, err |
100 | } |
101 | spec.pkg = bp.ImportPath |
102 | |
103 | } else { |
104 | // main is one of: |
105 | // "importpath" |
106 | // "importpath".member |
107 | // (*"importpath".type).fieldormethod (parens and star optional) |
108 | if err := parseObjectSpec(&spec, main); err != nil { |
109 | return nil, err |
110 | } |
111 | } |
112 | |
113 | if spec.searchFor != "" { |
114 | spec.fromName = spec.searchFor |
115 | } |
116 | |
117 | cwd, err := os.Getwd() |
118 | if err != nil { |
119 | return nil, err |
120 | } |
121 | |
122 | // Sanitize the package. |
123 | bp, err := ctxt.Import(spec.pkg, cwd, build.FindOnly) |
124 | if err != nil { |
125 | return nil, fmt.Errorf("can't find package %q", spec.pkg) |
126 | } |
127 | spec.pkg = bp.ImportPath |
128 | |
129 | if !isValidIdentifier(spec.fromName) { |
130 | return nil, fmt.Errorf("-from: invalid identifier %q", spec.fromName) |
131 | } |
132 | |
133 | if Verbose { |
134 | log.Printf("-from spec: %+v", spec) |
135 | } |
136 | |
137 | return &spec, nil |
138 | } |
139 | |
140 | // parseObjectSpec parses main as one of the non-filename forms of |
141 | // object specification. |
142 | func parseObjectSpec(spec *spec, main string) error { |
143 | // Parse main as a Go expression, albeit a strange one. |
144 | e, _ := parser.ParseExpr(main) |
145 | |
146 | if pkg := parseImportPath(e); pkg != "" { |
147 | // e.g. bytes or "encoding/json": a package |
148 | spec.pkg = pkg |
149 | if spec.searchFor == "" { |
150 | return fmt.Errorf("-from %q: package import path %q must have a ::name suffix", |
151 | main, main) |
152 | } |
153 | return nil |
154 | } |
155 | |
156 | if e, ok := e.(*ast.SelectorExpr); ok { |
157 | x := unparen(e.X) |
158 | |
159 | // Strip off star constructor, if any. |
160 | if star, ok := x.(*ast.StarExpr); ok { |
161 | x = star.X |
162 | } |
163 | |
164 | if pkg := parseImportPath(x); pkg != "" { |
165 | // package member e.g. "encoding/json".HTMLEscape |
166 | spec.pkg = pkg // e.g. "encoding/json" |
167 | spec.pkgMember = e.Sel.Name // e.g. "HTMLEscape" |
168 | spec.fromName = e.Sel.Name |
169 | return nil |
170 | } |
171 | |
172 | if x, ok := x.(*ast.SelectorExpr); ok { |
173 | // field/method of type e.g. ("encoding/json".Decoder).Decode |
174 | y := unparen(x.X) |
175 | if pkg := parseImportPath(y); pkg != "" { |
176 | spec.pkg = pkg // e.g. "encoding/json" |
177 | spec.pkgMember = x.Sel.Name // e.g. "Decoder" |
178 | spec.typeMember = e.Sel.Name // e.g. "Decode" |
179 | spec.fromName = e.Sel.Name |
180 | return nil |
181 | } |
182 | } |
183 | } |
184 | |
185 | return fmt.Errorf("-from %q: invalid expression", main) |
186 | } |
187 | |
188 | // parseImportPath returns the import path of the package denoted by e. |
189 | // Any import path may be represented as a string literal; |
190 | // single-segment import paths (e.g. "bytes") may also be represented as |
191 | // ast.Ident. parseImportPath returns "" for all other expressions. |
192 | func parseImportPath(e ast.Expr) string { |
193 | switch e := e.(type) { |
194 | case *ast.Ident: |
195 | return e.Name // e.g. bytes |
196 | |
197 | case *ast.BasicLit: |
198 | if e.Kind == token.STRING { |
199 | pkgname, _ := strconv.Unquote(e.Value) |
200 | return pkgname // e.g. "encoding/json" |
201 | } |
202 | } |
203 | return "" |
204 | } |
205 | |
206 | // parseOffsetFlag interprets the "-offset" flag value as a renaming specification. |
207 | func parseOffsetFlag(ctxt *build.Context, offsetFlag string) (*spec, error) { |
208 | var spec spec |
209 | // Validate -offset, e.g. file.go:#123 |
210 | parts := strings.Split(offsetFlag, ":#") |
211 | if len(parts) != 2 { |
212 | return nil, fmt.Errorf("-offset %q: invalid offset specification", offsetFlag) |
213 | } |
214 | |
215 | spec.filename = parts[0] |
216 | if !buildutil.FileExists(ctxt, spec.filename) { |
217 | return nil, fmt.Errorf("no such file: %s", spec.filename) |
218 | } |
219 | |
220 | bp, err := buildutil.ContainingPackage(ctxt, wd, spec.filename) |
221 | if err != nil { |
222 | return nil, err |
223 | } |
224 | spec.pkg = bp.ImportPath |
225 | |
226 | for _, r := range parts[1] { |
227 | if !isDigit(r) { |
228 | return nil, fmt.Errorf("-offset %q: non-numeric offset", offsetFlag) |
229 | } |
230 | } |
231 | spec.offset, err = strconv.Atoi(parts[1]) |
232 | if err != nil { |
233 | return nil, fmt.Errorf("-offset %q: non-numeric offset", offsetFlag) |
234 | } |
235 | |
236 | // Parse the file and check there's an identifier at that offset. |
237 | fset := token.NewFileSet() |
238 | f, err := buildutil.ParseFile(fset, ctxt, nil, wd, spec.filename, parser.ParseComments) |
239 | if err != nil { |
240 | return nil, fmt.Errorf("-offset %q: cannot parse file: %s", offsetFlag, err) |
241 | } |
242 | |
243 | id := identAtOffset(fset, f, spec.offset) |
244 | if id == nil { |
245 | return nil, fmt.Errorf("-offset %q: no identifier at this position", offsetFlag) |
246 | } |
247 | |
248 | spec.fromName = id.Name |
249 | |
250 | return &spec, nil |
251 | } |
252 | |
253 | var wd = func() string { |
254 | wd, err := os.Getwd() |
255 | if err != nil { |
256 | panic("cannot get working directory: " + err.Error()) |
257 | } |
258 | return wd |
259 | }() |
260 | |
261 | // For source trees built with 'go build', the -from or -offset |
262 | // spec identifies exactly one initial 'from' object to rename , |
263 | // but certain proprietary build systems allow a single file to |
264 | // appear in multiple packages (e.g. the test package contains a |
265 | // copy of its library), so there may be multiple objects for |
266 | // the same source entity. |
267 | |
268 | func findFromObjects(iprog *loader.Program, spec *spec) ([]types.Object, error) { |
269 | if spec.filename != "" { |
270 | return findFromObjectsInFile(iprog, spec) |
271 | } |
272 | |
273 | // Search for objects defined in specified package. |
274 | |
275 | // TODO(adonovan): the iprog.ImportMap has an entry {"main": ...} |
276 | // for main packages, even though that's not an import path. |
277 | // Seems like a bug. |
278 | // |
279 | // pkg := iprog.ImportMap[spec.pkg] |
280 | // if pkg == nil { |
281 | // return fmt.Errorf("cannot find package %s", spec.pkg) // can't happen? |
282 | // } |
283 | // info := iprog.AllPackages[pkg] |
284 | |
285 | // Workaround: lookup by value. |
286 | var info *loader.PackageInfo |
287 | var pkg *types.Package |
288 | for pkg, info = range iprog.AllPackages { |
289 | if pkg.Path() == spec.pkg { |
290 | break |
291 | } |
292 | } |
293 | if info == nil { |
294 | return nil, fmt.Errorf("package %q was not loaded", spec.pkg) |
295 | } |
296 | |
297 | objects, err := findObjects(info, spec) |
298 | if err != nil { |
299 | return nil, err |
300 | } |
301 | if len(objects) > 1 { |
302 | // ambiguous "*" scope query |
303 | return nil, ambiguityError(iprog.Fset, objects) |
304 | } |
305 | return objects, nil |
306 | } |
307 | |
308 | func findFromObjectsInFile(iprog *loader.Program, spec *spec) ([]types.Object, error) { |
309 | var fromObjects []types.Object |
310 | for _, info := range iprog.AllPackages { |
311 | // restrict to specified filename |
312 | // NB: under certain proprietary build systems, a given |
313 | // filename may appear in multiple packages. |
314 | for _, f := range info.Files { |
315 | thisFile := iprog.Fset.File(f.Pos()) |
316 | if !sameFile(thisFile.Name(), spec.filename) { |
317 | continue |
318 | } |
319 | // This package contains the query file. |
320 | |
321 | if spec.offset != 0 { |
322 | // We cannot refactor generated files since position information is invalidated. |
323 | if generated(f, thisFile) { |
324 | return nil, fmt.Errorf("cannot rename identifiers in generated file containing DO NOT EDIT marker: %s", thisFile.Name()) |
325 | } |
326 | |
327 | // Search for a specific ident by file/offset. |
328 | id := identAtOffset(iprog.Fset, f, spec.offset) |
329 | if id == nil { |
330 | // can't happen? |
331 | return nil, fmt.Errorf("identifier not found") |
332 | } |
333 | obj := info.Uses[id] |
334 | if obj == nil { |
335 | obj = info.Defs[id] |
336 | if obj == nil { |
337 | // Ident without Object. |
338 | |
339 | // Package clause? |
340 | pos := thisFile.Pos(spec.offset) |
341 | _, path, _ := iprog.PathEnclosingInterval(pos, pos) |
342 | if len(path) == 2 { // [Ident File] |
343 | // TODO(adonovan): support this case. |
344 | return nil, fmt.Errorf("cannot rename %q: renaming package clauses is not yet supported", |
345 | path[1].(*ast.File).Name.Name) |
346 | } |
347 | |
348 | // Implicit y in "switch y := x.(type) {"? |
349 | if obj := typeSwitchVar(&info.Info, path); obj != nil { |
350 | return []types.Object{obj}, nil |
351 | } |
352 | |
353 | // Probably a type error. |
354 | return nil, fmt.Errorf("cannot find object for %q", id.Name) |
355 | } |
356 | } |
357 | if obj.Pkg() == nil { |
358 | return nil, fmt.Errorf("cannot rename predeclared identifiers (%s)", obj) |
359 | |
360 | } |
361 | |
362 | fromObjects = append(fromObjects, obj) |
363 | } else { |
364 | // do a package-wide query |
365 | objects, err := findObjects(info, spec) |
366 | if err != nil { |
367 | return nil, err |
368 | } |
369 | |
370 | // filter results: only objects defined in thisFile |
371 | var filtered []types.Object |
372 | for _, obj := range objects { |
373 | if iprog.Fset.File(obj.Pos()) == thisFile { |
374 | filtered = append(filtered, obj) |
375 | } |
376 | } |
377 | if len(filtered) == 0 { |
378 | return nil, fmt.Errorf("no object %q declared in file %s", |
379 | spec.fromName, spec.filename) |
380 | } else if len(filtered) > 1 { |
381 | return nil, ambiguityError(iprog.Fset, filtered) |
382 | } |
383 | fromObjects = append(fromObjects, filtered[0]) |
384 | } |
385 | break |
386 | } |
387 | } |
388 | if len(fromObjects) == 0 { |
389 | // can't happen? |
390 | return nil, fmt.Errorf("file %s was not part of the loaded program", spec.filename) |
391 | } |
392 | return fromObjects, nil |
393 | } |
394 | |
395 | func typeSwitchVar(info *types.Info, path []ast.Node) types.Object { |
396 | if len(path) > 3 { |
397 | // [Ident AssignStmt TypeSwitchStmt...] |
398 | if sw, ok := path[2].(*ast.TypeSwitchStmt); ok { |
399 | // choose the first case. |
400 | if len(sw.Body.List) > 0 { |
401 | obj := info.Implicits[sw.Body.List[0].(*ast.CaseClause)] |
402 | if obj != nil { |
403 | return obj |
404 | } |
405 | } |
406 | } |
407 | } |
408 | return nil |
409 | } |
410 | |
411 | // On success, findObjects returns the list of objects named |
412 | // spec.fromName matching the spec. On success, the result has exactly |
413 | // one element unless spec.searchFor!="", in which case it has at least one |
414 | // element. |
415 | func findObjects(info *loader.PackageInfo, spec *spec) ([]types.Object, error) { |
416 | if spec.pkgMember == "" { |
417 | if spec.searchFor == "" { |
418 | panic(spec) |
419 | } |
420 | objects := searchDefs(&info.Info, spec.searchFor) |
421 | if objects == nil { |
422 | return nil, fmt.Errorf("no object %q declared in package %q", |
423 | spec.searchFor, info.Pkg.Path()) |
424 | } |
425 | return objects, nil |
426 | } |
427 | |
428 | pkgMember := info.Pkg.Scope().Lookup(spec.pkgMember) |
429 | if pkgMember == nil { |
430 | return nil, fmt.Errorf("package %q has no member %q", |
431 | info.Pkg.Path(), spec.pkgMember) |
432 | } |
433 | |
434 | var searchFunc *types.Func |
435 | if spec.typeMember == "" { |
436 | // package member |
437 | if spec.searchFor == "" { |
438 | return []types.Object{pkgMember}, nil |
439 | } |
440 | |
441 | // Search within pkgMember, which must be a function. |
442 | searchFunc, _ = pkgMember.(*types.Func) |
443 | if searchFunc == nil { |
444 | return nil, fmt.Errorf("cannot search for %q within %s %q", |
445 | spec.searchFor, objectKind(pkgMember), pkgMember) |
446 | } |
447 | } else { |
448 | // field/method of type |
449 | // e.g. (encoding/json.Decoder).Decode |
450 | // or ::x within it. |
451 | |
452 | tName, _ := pkgMember.(*types.TypeName) |
453 | if tName == nil { |
454 | return nil, fmt.Errorf("%s.%s is a %s, not a type", |
455 | info.Pkg.Path(), pkgMember.Name(), objectKind(pkgMember)) |
456 | } |
457 | |
458 | // search within named type. |
459 | obj, _, _ := types.LookupFieldOrMethod(tName.Type(), true, info.Pkg, spec.typeMember) |
460 | if obj == nil { |
461 | return nil, fmt.Errorf("cannot find field or method %q of %s %s.%s", |
462 | spec.typeMember, typeKind(tName.Type()), info.Pkg.Path(), tName.Name()) |
463 | } |
464 | |
465 | if spec.searchFor == "" { |
466 | // If it is an embedded field, return the type of the field. |
467 | if v, ok := obj.(*types.Var); ok && v.Anonymous() { |
468 | switch t := v.Type().(type) { |
469 | case *types.Pointer: |
470 | return []types.Object{t.Elem().(*types.Named).Obj()}, nil |
471 | case *types.Named: |
472 | return []types.Object{t.Obj()}, nil |
473 | } |
474 | } |
475 | return []types.Object{obj}, nil |
476 | } |
477 | |
478 | searchFunc, _ = obj.(*types.Func) |
479 | if searchFunc == nil { |
480 | return nil, fmt.Errorf("cannot search for local name %q within %s (%s.%s).%s; need a function", |
481 | spec.searchFor, objectKind(obj), info.Pkg.Path(), tName.Name(), |
482 | obj.Name()) |
483 | } |
484 | if isInterface(tName.Type()) { |
485 | return nil, fmt.Errorf("cannot search for local name %q within abstract method (%s.%s).%s", |
486 | spec.searchFor, info.Pkg.Path(), tName.Name(), searchFunc.Name()) |
487 | } |
488 | } |
489 | |
490 | // -- search within function or method -- |
491 | |
492 | decl := funcDecl(info, searchFunc) |
493 | if decl == nil { |
494 | return nil, fmt.Errorf("cannot find syntax for %s", searchFunc) // can't happen? |
495 | } |
496 | |
497 | var objects []types.Object |
498 | for _, obj := range searchDefs(&info.Info, spec.searchFor) { |
499 | // We use positions, not scopes, to determine whether |
500 | // the obj is within searchFunc. This is clumsy, but the |
501 | // alternative, using the types.Scope tree, doesn't |
502 | // account for non-lexical objects like fields and |
503 | // interface methods. |
504 | if decl.Pos() <= obj.Pos() && obj.Pos() < decl.End() && obj != searchFunc { |
505 | objects = append(objects, obj) |
506 | } |
507 | } |
508 | if objects == nil { |
509 | return nil, fmt.Errorf("no local definition of %q within %s", |
510 | spec.searchFor, searchFunc) |
511 | } |
512 | return objects, nil |
513 | } |
514 | |
515 | func funcDecl(info *loader.PackageInfo, fn *types.Func) *ast.FuncDecl { |
516 | for _, f := range info.Files { |
517 | for _, d := range f.Decls { |
518 | if d, ok := d.(*ast.FuncDecl); ok && info.Defs[d.Name] == fn { |
519 | return d |
520 | } |
521 | } |
522 | } |
523 | return nil |
524 | } |
525 | |
526 | func searchDefs(info *types.Info, name string) []types.Object { |
527 | var objects []types.Object |
528 | for id, obj := range info.Defs { |
529 | if obj == nil { |
530 | // e.g. blank ident. |
531 | // TODO(adonovan): but also implicit y in |
532 | // switch y := x.(type) |
533 | // Needs some thought. |
534 | continue |
535 | } |
536 | if id.Name == name { |
537 | objects = append(objects, obj) |
538 | } |
539 | } |
540 | return objects |
541 | } |
542 | |
543 | func identAtOffset(fset *token.FileSet, f *ast.File, offset int) *ast.Ident { |
544 | var found *ast.Ident |
545 | ast.Inspect(f, func(n ast.Node) bool { |
546 | if id, ok := n.(*ast.Ident); ok { |
547 | idpos := fset.Position(id.Pos()).Offset |
548 | if idpos <= offset && offset < idpos+len(id.Name) { |
549 | found = id |
550 | } |
551 | } |
552 | return found == nil // keep traversing only until found |
553 | }) |
554 | return found |
555 | } |
556 | |
557 | // ambiguityError returns an error describing an ambiguous "*" scope query. |
558 | func ambiguityError(fset *token.FileSet, objects []types.Object) error { |
559 | var buf bytes.Buffer |
560 | for i, obj := range objects { |
561 | if i > 0 { |
562 | buf.WriteString(", ") |
563 | } |
564 | posn := fset.Position(obj.Pos()) |
565 | fmt.Fprintf(&buf, "%s at %s:%d:%d", |
566 | objectKind(obj), filepath.Base(posn.Filename), posn.Line, posn.Column) |
567 | } |
568 | return fmt.Errorf("ambiguous specifier %s matches %s", |
569 | objects[0].Name(), buf.String()) |
570 | } |
571 | |
572 | // Matches cgo generated comment as well as the proposed standard: |
573 | // |
574 | // https://golang.org/s/generatedcode |
575 | var generatedRx = regexp.MustCompile(`// .*DO NOT EDIT\.?`) |
576 | |
577 | // generated reports whether ast.File is a generated file. |
578 | func generated(f *ast.File, tokenFile *token.File) bool { |
579 | |
580 | // Iterate over the comments in the file |
581 | for _, commentGroup := range f.Comments { |
582 | for _, comment := range commentGroup.List { |
583 | if matched := generatedRx.MatchString(comment.Text); matched { |
584 | // Check if comment is at the beginning of the line in source |
585 | if pos := tokenFile.Position(comment.Slash); pos.Column == 1 { |
586 | return true |
587 | } |
588 | } |
589 | } |
590 | } |
591 | return false |
592 | } |
593 |
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