| 1 | // Copyright 2013 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 astutil contains common utilities for working with the Go AST. |
| 6 | package astutil // import "golang.org/x/tools/go/ast/astutil" |
| 7 | |
| 8 | import ( |
| 9 | "fmt" |
| 10 | "go/ast" |
| 11 | "go/token" |
| 12 | "strconv" |
| 13 | "strings" |
| 14 | ) |
| 15 | |
| 16 | // AddImport adds the import path to the file f, if absent. |
| 17 | func AddImport(fset *token.FileSet, f *ast.File, path string) (added bool) { |
| 18 | return AddNamedImport(fset, f, "", path) |
| 19 | } |
| 20 | |
| 21 | // AddNamedImport adds the import with the given name and path to the file f, if absent. |
| 22 | // If name is not empty, it is used to rename the import. |
| 23 | // |
| 24 | // For example, calling |
| 25 | // |
| 26 | // AddNamedImport(fset, f, "pathpkg", "path") |
| 27 | // |
| 28 | // adds |
| 29 | // |
| 30 | // import pathpkg "path" |
| 31 | func AddNamedImport(fset *token.FileSet, f *ast.File, name, path string) (added bool) { |
| 32 | if imports(f, name, path) { |
| 33 | return false |
| 34 | } |
| 35 | |
| 36 | newImport := &ast.ImportSpec{ |
| 37 | Path: &ast.BasicLit{ |
| 38 | Kind: token.STRING, |
| 39 | Value: strconv.Quote(path), |
| 40 | }, |
| 41 | } |
| 42 | if name != "" { |
| 43 | newImport.Name = &ast.Ident{Name: name} |
| 44 | } |
| 45 | |
| 46 | // Find an import decl to add to. |
| 47 | // The goal is to find an existing import |
| 48 | // whose import path has the longest shared |
| 49 | // prefix with path. |
| 50 | var ( |
| 51 | bestMatch = -1 // length of longest shared prefix |
| 52 | lastImport = -1 // index in f.Decls of the file's final import decl |
| 53 | impDecl *ast.GenDecl // import decl containing the best match |
| 54 | impIndex = -1 // spec index in impDecl containing the best match |
| 55 | |
| 56 | isThirdPartyPath = isThirdParty(path) |
| 57 | ) |
| 58 | for i, decl := range f.Decls { |
| 59 | gen, ok := decl.(*ast.GenDecl) |
| 60 | if ok && gen.Tok == token.IMPORT { |
| 61 | lastImport = i |
| 62 | // Do not add to import "C", to avoid disrupting the |
| 63 | // association with its doc comment, breaking cgo. |
| 64 | if declImports(gen, "C") { |
| 65 | continue |
| 66 | } |
| 67 | |
| 68 | // Match an empty import decl if that's all that is available. |
| 69 | if len(gen.Specs) == 0 && bestMatch == -1 { |
| 70 | impDecl = gen |
| 71 | } |
| 72 | |
| 73 | // Compute longest shared prefix with imports in this group and find best |
| 74 | // matched import spec. |
| 75 | // 1. Always prefer import spec with longest shared prefix. |
| 76 | // 2. While match length is 0, |
| 77 | // - for stdlib package: prefer first import spec. |
| 78 | // - for third party package: prefer first third party import spec. |
| 79 | // We cannot use last import spec as best match for third party package |
| 80 | // because grouped imports are usually placed last by goimports -local |
| 81 | // flag. |
| 82 | // See issue #19190. |
| 83 | seenAnyThirdParty := false |
| 84 | for j, spec := range gen.Specs { |
| 85 | impspec := spec.(*ast.ImportSpec) |
| 86 | p := importPath(impspec) |
| 87 | n := matchLen(p, path) |
| 88 | if n > bestMatch || (bestMatch == 0 && !seenAnyThirdParty && isThirdPartyPath) { |
| 89 | bestMatch = n |
| 90 | impDecl = gen |
| 91 | impIndex = j |
| 92 | } |
| 93 | seenAnyThirdParty = seenAnyThirdParty || isThirdParty(p) |
| 94 | } |
| 95 | } |
| 96 | } |
| 97 | |
| 98 | // If no import decl found, add one after the last import. |
| 99 | if impDecl == nil { |
| 100 | impDecl = &ast.GenDecl{ |
| 101 | Tok: token.IMPORT, |
| 102 | } |
| 103 | if lastImport >= 0 { |
| 104 | impDecl.TokPos = f.Decls[lastImport].End() |
| 105 | } else { |
| 106 | // There are no existing imports. |
| 107 | // Our new import, preceded by a blank line, goes after the package declaration |
| 108 | // and after the comment, if any, that starts on the same line as the |
| 109 | // package declaration. |
| 110 | impDecl.TokPos = f.Package |
| 111 | |
| 112 | file := fset.File(f.Package) |
| 113 | pkgLine := file.Line(f.Package) |
| 114 | for _, c := range f.Comments { |
| 115 | if file.Line(c.Pos()) > pkgLine { |
| 116 | break |
| 117 | } |
| 118 | // +2 for a blank line |
| 119 | impDecl.TokPos = c.End() + 2 |
| 120 | } |
| 121 | } |
| 122 | f.Decls = append(f.Decls, nil) |
| 123 | copy(f.Decls[lastImport+2:], f.Decls[lastImport+1:]) |
| 124 | f.Decls[lastImport+1] = impDecl |
| 125 | } |
| 126 | |
| 127 | // Insert new import at insertAt. |
| 128 | insertAt := 0 |
| 129 | if impIndex >= 0 { |
| 130 | // insert after the found import |
| 131 | insertAt = impIndex + 1 |
| 132 | } |
| 133 | impDecl.Specs = append(impDecl.Specs, nil) |
| 134 | copy(impDecl.Specs[insertAt+1:], impDecl.Specs[insertAt:]) |
| 135 | impDecl.Specs[insertAt] = newImport |
| 136 | pos := impDecl.Pos() |
| 137 | if insertAt > 0 { |
| 138 | // If there is a comment after an existing import, preserve the comment |
| 139 | // position by adding the new import after the comment. |
| 140 | if spec, ok := impDecl.Specs[insertAt-1].(*ast.ImportSpec); ok && spec.Comment != nil { |
| 141 | pos = spec.Comment.End() |
| 142 | } else { |
| 143 | // Assign same position as the previous import, |
| 144 | // so that the sorter sees it as being in the same block. |
| 145 | pos = impDecl.Specs[insertAt-1].Pos() |
| 146 | } |
| 147 | } |
| 148 | if newImport.Name != nil { |
| 149 | newImport.Name.NamePos = pos |
| 150 | } |
| 151 | newImport.Path.ValuePos = pos |
| 152 | newImport.EndPos = pos |
| 153 | |
| 154 | // Clean up parens. impDecl contains at least one spec. |
| 155 | if len(impDecl.Specs) == 1 { |
| 156 | // Remove unneeded parens. |
| 157 | impDecl.Lparen = token.NoPos |
| 158 | } else if !impDecl.Lparen.IsValid() { |
| 159 | // impDecl needs parens added. |
| 160 | impDecl.Lparen = impDecl.Specs[0].Pos() |
| 161 | } |
| 162 | |
| 163 | f.Imports = append(f.Imports, newImport) |
| 164 | |
| 165 | if len(f.Decls) <= 1 { |
| 166 | return true |
| 167 | } |
| 168 | |
| 169 | // Merge all the import declarations into the first one. |
| 170 | var first *ast.GenDecl |
| 171 | for i := 0; i < len(f.Decls); i++ { |
| 172 | decl := f.Decls[i] |
| 173 | gen, ok := decl.(*ast.GenDecl) |
| 174 | if !ok || gen.Tok != token.IMPORT || declImports(gen, "C") { |
| 175 | continue |
| 176 | } |
| 177 | if first == nil { |
| 178 | first = gen |
| 179 | continue // Don't touch the first one. |
| 180 | } |
| 181 | // We now know there is more than one package in this import |
| 182 | // declaration. Ensure that it ends up parenthesized. |
| 183 | first.Lparen = first.Pos() |
| 184 | // Move the imports of the other import declaration to the first one. |
| 185 | for _, spec := range gen.Specs { |
| 186 | spec.(*ast.ImportSpec).Path.ValuePos = first.Pos() |
| 187 | first.Specs = append(first.Specs, spec) |
| 188 | } |
| 189 | f.Decls = append(f.Decls[:i], f.Decls[i+1:]...) |
| 190 | i-- |
| 191 | } |
| 192 | |
| 193 | return true |
| 194 | } |
| 195 | |
| 196 | func isThirdParty(importPath string) bool { |
| 197 | // Third party package import path usually contains "." (".com", ".org", ...) |
| 198 | // This logic is taken from golang.org/x/tools/imports package. |
| 199 | return strings.Contains(importPath, ".") |
| 200 | } |
| 201 | |
| 202 | // DeleteImport deletes the import path from the file f, if present. |
| 203 | // If there are duplicate import declarations, all matching ones are deleted. |
| 204 | func DeleteImport(fset *token.FileSet, f *ast.File, path string) (deleted bool) { |
| 205 | return DeleteNamedImport(fset, f, "", path) |
| 206 | } |
| 207 | |
| 208 | // DeleteNamedImport deletes the import with the given name and path from the file f, if present. |
| 209 | // If there are duplicate import declarations, all matching ones are deleted. |
| 210 | func DeleteNamedImport(fset *token.FileSet, f *ast.File, name, path string) (deleted bool) { |
| 211 | var delspecs []*ast.ImportSpec |
| 212 | var delcomments []*ast.CommentGroup |
| 213 | |
| 214 | // Find the import nodes that import path, if any. |
| 215 | for i := 0; i < len(f.Decls); i++ { |
| 216 | decl := f.Decls[i] |
| 217 | gen, ok := decl.(*ast.GenDecl) |
| 218 | if !ok || gen.Tok != token.IMPORT { |
| 219 | continue |
| 220 | } |
| 221 | for j := 0; j < len(gen.Specs); j++ { |
| 222 | spec := gen.Specs[j] |
| 223 | impspec := spec.(*ast.ImportSpec) |
| 224 | if importName(impspec) != name || importPath(impspec) != path { |
| 225 | continue |
| 226 | } |
| 227 | |
| 228 | // We found an import spec that imports path. |
| 229 | // Delete it. |
| 230 | delspecs = append(delspecs, impspec) |
| 231 | deleted = true |
| 232 | copy(gen.Specs[j:], gen.Specs[j+1:]) |
| 233 | gen.Specs = gen.Specs[:len(gen.Specs)-1] |
| 234 | |
| 235 | // If this was the last import spec in this decl, |
| 236 | // delete the decl, too. |
| 237 | if len(gen.Specs) == 0 { |
| 238 | copy(f.Decls[i:], f.Decls[i+1:]) |
| 239 | f.Decls = f.Decls[:len(f.Decls)-1] |
| 240 | i-- |
| 241 | break |
| 242 | } else if len(gen.Specs) == 1 { |
| 243 | if impspec.Doc != nil { |
| 244 | delcomments = append(delcomments, impspec.Doc) |
| 245 | } |
| 246 | if impspec.Comment != nil { |
| 247 | delcomments = append(delcomments, impspec.Comment) |
| 248 | } |
| 249 | for _, cg := range f.Comments { |
| 250 | // Found comment on the same line as the import spec. |
| 251 | if cg.End() < impspec.Pos() && fset.Position(cg.End()).Line == fset.Position(impspec.Pos()).Line { |
| 252 | delcomments = append(delcomments, cg) |
| 253 | break |
| 254 | } |
| 255 | } |
| 256 | |
| 257 | spec := gen.Specs[0].(*ast.ImportSpec) |
| 258 | |
| 259 | // Move the documentation right after the import decl. |
| 260 | if spec.Doc != nil { |
| 261 | for fset.Position(gen.TokPos).Line+1 < fset.Position(spec.Doc.Pos()).Line { |
| 262 | fset.File(gen.TokPos).MergeLine(fset.Position(gen.TokPos).Line) |
| 263 | } |
| 264 | } |
| 265 | for _, cg := range f.Comments { |
| 266 | if cg.End() < spec.Pos() && fset.Position(cg.End()).Line == fset.Position(spec.Pos()).Line { |
| 267 | for fset.Position(gen.TokPos).Line+1 < fset.Position(spec.Pos()).Line { |
| 268 | fset.File(gen.TokPos).MergeLine(fset.Position(gen.TokPos).Line) |
| 269 | } |
| 270 | break |
| 271 | } |
| 272 | } |
| 273 | } |
| 274 | if j > 0 { |
| 275 | lastImpspec := gen.Specs[j-1].(*ast.ImportSpec) |
| 276 | lastLine := fset.PositionFor(lastImpspec.Path.ValuePos, false).Line |
| 277 | line := fset.PositionFor(impspec.Path.ValuePos, false).Line |
| 278 | |
| 279 | // We deleted an entry but now there may be |
| 280 | // a blank line-sized hole where the import was. |
| 281 | if line-lastLine > 1 || !gen.Rparen.IsValid() { |
| 282 | // There was a blank line immediately preceding the deleted import, |
| 283 | // so there's no need to close the hole. The right parenthesis is |
| 284 | // invalid after AddImport to an import statement without parenthesis. |
| 285 | // Do nothing. |
| 286 | } else if line != fset.File(gen.Rparen).LineCount() { |
| 287 | // There was no blank line. Close the hole. |
| 288 | fset.File(gen.Rparen).MergeLine(line) |
| 289 | } |
| 290 | } |
| 291 | j-- |
| 292 | } |
| 293 | } |
| 294 | |
| 295 | // Delete imports from f.Imports. |
| 296 | for i := 0; i < len(f.Imports); i++ { |
| 297 | imp := f.Imports[i] |
| 298 | for j, del := range delspecs { |
| 299 | if imp == del { |
| 300 | copy(f.Imports[i:], f.Imports[i+1:]) |
| 301 | f.Imports = f.Imports[:len(f.Imports)-1] |
| 302 | copy(delspecs[j:], delspecs[j+1:]) |
| 303 | delspecs = delspecs[:len(delspecs)-1] |
| 304 | i-- |
| 305 | break |
| 306 | } |
| 307 | } |
| 308 | } |
| 309 | |
| 310 | // Delete comments from f.Comments. |
| 311 | for i := 0; i < len(f.Comments); i++ { |
| 312 | cg := f.Comments[i] |
| 313 | for j, del := range delcomments { |
| 314 | if cg == del { |
| 315 | copy(f.Comments[i:], f.Comments[i+1:]) |
| 316 | f.Comments = f.Comments[:len(f.Comments)-1] |
| 317 | copy(delcomments[j:], delcomments[j+1:]) |
| 318 | delcomments = delcomments[:len(delcomments)-1] |
| 319 | i-- |
| 320 | break |
| 321 | } |
| 322 | } |
| 323 | } |
| 324 | |
| 325 | if len(delspecs) > 0 { |
| 326 | panic(fmt.Sprintf("deleted specs from Decls but not Imports: %v", delspecs)) |
| 327 | } |
| 328 | |
| 329 | return |
| 330 | } |
| 331 | |
| 332 | // RewriteImport rewrites any import of path oldPath to path newPath. |
| 333 | func RewriteImport(fset *token.FileSet, f *ast.File, oldPath, newPath string) (rewrote bool) { |
| 334 | for _, imp := range f.Imports { |
| 335 | if importPath(imp) == oldPath { |
| 336 | rewrote = true |
| 337 | // record old End, because the default is to compute |
| 338 | // it using the length of imp.Path.Value. |
| 339 | imp.EndPos = imp.End() |
| 340 | imp.Path.Value = strconv.Quote(newPath) |
| 341 | } |
| 342 | } |
| 343 | return |
| 344 | } |
| 345 | |
| 346 | // UsesImport reports whether a given import is used. |
| 347 | func UsesImport(f *ast.File, path string) (used bool) { |
| 348 | spec := importSpec(f, path) |
| 349 | if spec == nil { |
| 350 | return |
| 351 | } |
| 352 | |
| 353 | name := spec.Name.String() |
| 354 | switch name { |
| 355 | case "<nil>": |
| 356 | // If the package name is not explicitly specified, |
| 357 | // make an educated guess. This is not guaranteed to be correct. |
| 358 | lastSlash := strings.LastIndex(path, "/") |
| 359 | if lastSlash == -1 { |
| 360 | name = path |
| 361 | } else { |
| 362 | name = path[lastSlash+1:] |
| 363 | } |
| 364 | case "_", ".": |
| 365 | // Not sure if this import is used - err on the side of caution. |
| 366 | return true |
| 367 | } |
| 368 | |
| 369 | ast.Walk(visitFn(func(n ast.Node) { |
| 370 | sel, ok := n.(*ast.SelectorExpr) |
| 371 | if ok && isTopName(sel.X, name) { |
| 372 | used = true |
| 373 | } |
| 374 | }), f) |
| 375 | |
| 376 | return |
| 377 | } |
| 378 | |
| 379 | type visitFn func(node ast.Node) |
| 380 | |
| 381 | func (fn visitFn) Visit(node ast.Node) ast.Visitor { |
| 382 | fn(node) |
| 383 | return fn |
| 384 | } |
| 385 | |
| 386 | // imports reports whether f has an import with the specified name and path. |
| 387 | func imports(f *ast.File, name, path string) bool { |
| 388 | for _, s := range f.Imports { |
| 389 | if importName(s) == name && importPath(s) == path { |
| 390 | return true |
| 391 | } |
| 392 | } |
| 393 | return false |
| 394 | } |
| 395 | |
| 396 | // importSpec returns the import spec if f imports path, |
| 397 | // or nil otherwise. |
| 398 | func importSpec(f *ast.File, path string) *ast.ImportSpec { |
| 399 | for _, s := range f.Imports { |
| 400 | if importPath(s) == path { |
| 401 | return s |
| 402 | } |
| 403 | } |
| 404 | return nil |
| 405 | } |
| 406 | |
| 407 | // importName returns the name of s, |
| 408 | // or "" if the import is not named. |
| 409 | func importName(s *ast.ImportSpec) string { |
| 410 | if s.Name == nil { |
| 411 | return "" |
| 412 | } |
| 413 | return s.Name.Name |
| 414 | } |
| 415 | |
| 416 | // importPath returns the unquoted import path of s, |
| 417 | // or "" if the path is not properly quoted. |
| 418 | func importPath(s *ast.ImportSpec) string { |
| 419 | t, err := strconv.Unquote(s.Path.Value) |
| 420 | if err != nil { |
| 421 | return "" |
| 422 | } |
| 423 | return t |
| 424 | } |
| 425 | |
| 426 | // declImports reports whether gen contains an import of path. |
| 427 | func declImports(gen *ast.GenDecl, path string) bool { |
| 428 | if gen.Tok != token.IMPORT { |
| 429 | return false |
| 430 | } |
| 431 | for _, spec := range gen.Specs { |
| 432 | impspec := spec.(*ast.ImportSpec) |
| 433 | if importPath(impspec) == path { |
| 434 | return true |
| 435 | } |
| 436 | } |
| 437 | return false |
| 438 | } |
| 439 | |
| 440 | // matchLen returns the length of the longest path segment prefix shared by x and y. |
| 441 | func matchLen(x, y string) int { |
| 442 | n := 0 |
| 443 | for i := 0; i < len(x) && i < len(y) && x[i] == y[i]; i++ { |
| 444 | if x[i] == '/' { |
| 445 | n++ |
| 446 | } |
| 447 | } |
| 448 | return n |
| 449 | } |
| 450 | |
| 451 | // isTopName returns true if n is a top-level unresolved identifier with the given name. |
| 452 | func isTopName(n ast.Expr, name string) bool { |
| 453 | id, ok := n.(*ast.Ident) |
| 454 | return ok && id.Name == name && id.Obj == nil |
| 455 | } |
| 456 | |
| 457 | // Imports returns the file imports grouped by paragraph. |
| 458 | func Imports(fset *token.FileSet, f *ast.File) [][]*ast.ImportSpec { |
| 459 | var groups [][]*ast.ImportSpec |
| 460 | |
| 461 | for _, decl := range f.Decls { |
| 462 | genDecl, ok := decl.(*ast.GenDecl) |
| 463 | if !ok || genDecl.Tok != token.IMPORT { |
| 464 | break |
| 465 | } |
| 466 | |
| 467 | group := []*ast.ImportSpec{} |
| 468 | |
| 469 | var lastLine int |
| 470 | for _, spec := range genDecl.Specs { |
| 471 | importSpec := spec.(*ast.ImportSpec) |
| 472 | pos := importSpec.Path.ValuePos |
| 473 | line := fset.Position(pos).Line |
| 474 | if lastLine > 0 && pos > 0 && line-lastLine > 1 { |
| 475 | groups = append(groups, group) |
| 476 | group = []*ast.ImportSpec{} |
| 477 | } |
| 478 | group = append(group, importSpec) |
| 479 | lastLine = line |
| 480 | } |
| 481 | groups = append(groups, group) |
| 482 | } |
| 483 | |
| 484 | return groups |
| 485 | } |
| 486 |
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