1 //===--- SortJavaScriptImports.cpp - Sort ES6 Imports -----------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 /// 9 /// \file 10 /// This file implements a sort operation for JavaScript ES6 imports. 11 /// 12 //===----------------------------------------------------------------------===// 13 14 #include "SortJavaScriptImports.h" 15 #include "TokenAnalyzer.h" 16 #include "TokenAnnotator.h" 17 #include "clang/Basic/Diagnostic.h" 18 #include "clang/Basic/DiagnosticOptions.h" 19 #include "clang/Basic/LLVM.h" 20 #include "clang/Basic/SourceLocation.h" 21 #include "clang/Basic/SourceManager.h" 22 #include "clang/Basic/TokenKinds.h" 23 #include "clang/Format/Format.h" 24 #include "llvm/ADT/STLExtras.h" 25 #include "llvm/ADT/SmallVector.h" 26 #include "llvm/Support/Debug.h" 27 #include <algorithm> 28 #include <string> 29 30 #define DEBUG_TYPE "format-formatter" 31 32 namespace clang { 33 namespace format { 34 35 class FormatTokenLexer; 36 37 using clang::format::FormatStyle; 38 39 // An imported symbol in a JavaScript ES6 import/export, possibly aliased. 40 struct JsImportedSymbol { 41 StringRef Symbol; 42 StringRef Alias; 43 SourceRange Range; 44 45 bool operator==(const JsImportedSymbol &RHS) const { 46 // Ignore Range for comparison, it is only used to stitch code together, 47 // but imports at different code locations are still conceptually the same. 48 return Symbol == RHS.Symbol && Alias == RHS.Alias; 49 } 50 }; 51 52 // An ES6 module reference. 53 // 54 // ES6 implements a module system, where individual modules (~= source files) 55 // can reference other modules, either importing symbols from them, or exporting 56 // symbols from them: 57 // import {foo} from 'foo'; 58 // export {foo}; 59 // export {bar} from 'bar'; 60 // 61 // `export`s with URLs are syntactic sugar for an import of the symbol from the 62 // URL, followed by an export of the symbol, allowing this code to treat both 63 // statements more or less identically, with the exception being that `export`s 64 // are sorted last. 65 // 66 // imports and exports support individual symbols, but also a wildcard syntax: 67 // import * as prefix from 'foo'; 68 // export * from 'bar'; 69 // 70 // This struct represents both exports and imports to build up the information 71 // required for sorting module references. 72 struct JsModuleReference { 73 bool FormattingOff = false; 74 bool IsExport = false; 75 bool IsTypeOnly = false; 76 // Module references are sorted into these categories, in order. 77 enum ReferenceCategory { 78 SIDE_EFFECT, // "import 'something';" 79 ABSOLUTE, // from 'something' 80 RELATIVE_PARENT, // from '../*' 81 RELATIVE, // from './*' 82 ALIAS, // import X = A.B; 83 }; 84 ReferenceCategory Category = ReferenceCategory::SIDE_EFFECT; 85 // The URL imported, e.g. `import .. from 'url';`. Empty for `export {a, b};`. 86 StringRef URL; 87 // Prefix from "import * as prefix". Empty for symbol imports and `export *`. 88 // Implies an empty names list. 89 StringRef Prefix; 90 // Default import from "import DefaultName from '...';". 91 StringRef DefaultImport; 92 // Symbols from `import {SymbolA, SymbolB, ...} from ...;`. 93 SmallVector<JsImportedSymbol, 1> Symbols; 94 // Whether some symbols were merged into this one. Controls if the module 95 // reference needs re-formatting. 96 bool SymbolsMerged = false; 97 // The source location just after { and just before } in the import. 98 // Extracted eagerly to allow modification of Symbols later on. 99 SourceLocation SymbolsStart, SymbolsEnd; 100 // Textual position of the import/export, including preceding and trailing 101 // comments. 102 SourceRange Range; 103 }; 104 105 bool operator<(const JsModuleReference &LHS, const JsModuleReference &RHS) { 106 if (LHS.IsExport != RHS.IsExport) 107 return LHS.IsExport < RHS.IsExport; 108 if (LHS.Category != RHS.Category) 109 return LHS.Category < RHS.Category; 110 if (LHS.Category == JsModuleReference::ReferenceCategory::SIDE_EFFECT || 111 LHS.Category == JsModuleReference::ReferenceCategory::ALIAS) { 112 // Side effect imports and aliases might be ordering sensitive. Consider 113 // them equal so that they maintain their relative order in the stable sort 114 // below. This retains transitivity because LHS.Category == RHS.Category 115 // here. 116 return false; 117 } 118 // Empty URLs sort *last* (for export {...};). 119 if (LHS.URL.empty() != RHS.URL.empty()) 120 return LHS.URL.empty() < RHS.URL.empty(); 121 if (int Res = LHS.URL.compare_insensitive(RHS.URL)) 122 return Res < 0; 123 // '*' imports (with prefix) sort before {a, b, ...} imports. 124 if (LHS.Prefix.empty() != RHS.Prefix.empty()) 125 return LHS.Prefix.empty() < RHS.Prefix.empty(); 126 if (LHS.Prefix != RHS.Prefix) 127 return LHS.Prefix > RHS.Prefix; 128 return false; 129 } 130 131 // JavaScriptImportSorter sorts JavaScript ES6 imports and exports. It is 132 // implemented as a TokenAnalyzer because ES6 imports have substantial syntactic 133 // structure, making it messy to sort them using regular expressions. 134 class JavaScriptImportSorter : public TokenAnalyzer { 135 public: 136 JavaScriptImportSorter(const Environment &Env, const FormatStyle &Style) 137 : TokenAnalyzer(Env, Style), 138 FileContents(Env.getSourceManager().getBufferData(Env.getFileID())) { 139 // FormatToken.Tok starts out in an uninitialized state. 140 invalidToken.Tok.startToken(); 141 } 142 143 std::pair<tooling::Replacements, unsigned> 144 analyze(TokenAnnotator &Annotator, 145 SmallVectorImpl<AnnotatedLine *> &AnnotatedLines, 146 FormatTokenLexer &Tokens) override { 147 tooling::Replacements Result; 148 AffectedRangeMgr.computeAffectedLines(AnnotatedLines); 149 150 const AdditionalKeywords &Keywords = Tokens.getKeywords(); 151 SmallVector<JsModuleReference, 16> References; 152 AnnotatedLine *FirstNonImportLine; 153 std::tie(References, FirstNonImportLine) = 154 parseModuleReferences(Keywords, AnnotatedLines); 155 156 if (References.empty()) 157 return {Result, 0}; 158 159 // The text range of all parsed imports, to be replaced later. 160 SourceRange InsertionPoint = References[0].Range; 161 InsertionPoint.setEnd(References[References.size() - 1].Range.getEnd()); 162 163 References = sortModuleReferences(References); 164 165 std::string ReferencesText; 166 for (unsigned I = 0, E = References.size(); I != E; ++I) { 167 JsModuleReference Reference = References[I]; 168 appendReference(ReferencesText, Reference); 169 if (I + 1 < E) { 170 // Insert breaks between imports and exports. 171 ReferencesText += "\n"; 172 // Separate imports groups with two line breaks, but keep all exports 173 // in a single group. 174 if (!Reference.IsExport && 175 (Reference.IsExport != References[I + 1].IsExport || 176 Reference.Category != References[I + 1].Category)) { 177 ReferencesText += "\n"; 178 } 179 } 180 } 181 llvm::StringRef PreviousText = getSourceText(InsertionPoint); 182 if (ReferencesText == PreviousText) 183 return {Result, 0}; 184 185 // The loop above might collapse previously existing line breaks between 186 // import blocks, and thus shrink the file. SortIncludes must not shrink 187 // overall source length as there is currently no re-calculation of ranges 188 // after applying source sorting. 189 // This loop just backfills trailing spaces after the imports, which are 190 // harmless and will be stripped by the subsequent formatting pass. 191 // FIXME: A better long term fix is to re-calculate Ranges after sorting. 192 unsigned PreviousSize = PreviousText.size(); 193 while (ReferencesText.size() < PreviousSize) 194 ReferencesText += " "; 195 196 // Separate references from the main code body of the file. 197 if (FirstNonImportLine && FirstNonImportLine->First->NewlinesBefore < 2 && 198 !(FirstNonImportLine->First->is(tok::comment) && 199 isClangFormatOn(FirstNonImportLine->First->TokenText.trim()))) { 200 ReferencesText += "\n"; 201 } 202 203 LLVM_DEBUG(llvm::dbgs() << "Replacing imports:\n" 204 << PreviousText << "\nwith:\n" 205 << ReferencesText << "\n"); 206 auto Err = Result.add(tooling::Replacement( 207 Env.getSourceManager(), CharSourceRange::getCharRange(InsertionPoint), 208 ReferencesText)); 209 // FIXME: better error handling. For now, just print error message and skip 210 // the replacement for the release version. 211 if (Err) { 212 llvm::errs() << llvm::toString(std::move(Err)) << "\n"; 213 assert(false); 214 } 215 216 return {Result, 0}; 217 } 218 219 private: 220 FormatToken *Current = nullptr; 221 FormatToken *LineEnd = nullptr; 222 223 FormatToken invalidToken; 224 225 StringRef FileContents; 226 227 void skipComments() { Current = skipComments(Current); } 228 229 FormatToken *skipComments(FormatToken *Tok) { 230 while (Tok && Tok->is(tok::comment)) 231 Tok = Tok->Next; 232 return Tok; 233 } 234 235 void nextToken() { 236 Current = Current->Next; 237 skipComments(); 238 if (!Current || Current == LineEnd->Next) { 239 // Set the current token to an invalid token, so that further parsing on 240 // this line fails. 241 Current = &invalidToken; 242 } 243 } 244 245 StringRef getSourceText(SourceRange Range) { 246 return getSourceText(Range.getBegin(), Range.getEnd()); 247 } 248 249 StringRef getSourceText(SourceLocation Begin, SourceLocation End) { 250 const SourceManager &SM = Env.getSourceManager(); 251 return FileContents.substr(SM.getFileOffset(Begin), 252 SM.getFileOffset(End) - SM.getFileOffset(Begin)); 253 } 254 255 // Sorts the given module references. 256 // Imports can have formatting disabled (FormattingOff), so the code below 257 // skips runs of "no-formatting" module references, and sorts/merges the 258 // references that have formatting enabled in individual chunks. 259 SmallVector<JsModuleReference, 16> 260 sortModuleReferences(const SmallVector<JsModuleReference, 16> &References) { 261 // Sort module references. 262 // Imports can have formatting disabled (FormattingOff), so the code below 263 // skips runs of "no-formatting" module references, and sorts other 264 // references per group. 265 const auto *Start = References.begin(); 266 SmallVector<JsModuleReference, 16> ReferencesSorted; 267 while (Start != References.end()) { 268 while (Start != References.end() && Start->FormattingOff) { 269 // Skip over all imports w/ disabled formatting. 270 ReferencesSorted.push_back(*Start); 271 ++Start; 272 } 273 SmallVector<JsModuleReference, 16> SortChunk; 274 while (Start != References.end() && !Start->FormattingOff) { 275 // Skip over all imports w/ disabled formatting. 276 SortChunk.push_back(*Start); 277 ++Start; 278 } 279 llvm::stable_sort(SortChunk); 280 mergeModuleReferences(SortChunk); 281 ReferencesSorted.insert(ReferencesSorted.end(), SortChunk.begin(), 282 SortChunk.end()); 283 } 284 return ReferencesSorted; 285 } 286 287 // Merge module references. 288 // After sorting, find all references that import named symbols from the 289 // same URL and merge their names. E.g. 290 // import {X} from 'a'; 291 // import {Y} from 'a'; 292 // should be rewritten to: 293 // import {X, Y} from 'a'; 294 // Note: this modifies the passed in ``References`` vector (by removing no 295 // longer needed references). 296 void mergeModuleReferences(SmallVector<JsModuleReference, 16> &References) { 297 if (References.empty()) 298 return; 299 JsModuleReference *PreviousReference = References.begin(); 300 auto *Reference = std::next(References.begin()); 301 while (Reference != References.end()) { 302 // Skip: 303 // import 'foo'; 304 // import * as foo from 'foo'; on either previous or this. 305 // import Default from 'foo'; on either previous or this. 306 // mismatching 307 if (Reference->Category == JsModuleReference::SIDE_EFFECT || 308 PreviousReference->Category == JsModuleReference::SIDE_EFFECT || 309 Reference->IsExport != PreviousReference->IsExport || 310 Reference->IsTypeOnly != PreviousReference->IsTypeOnly || 311 !PreviousReference->Prefix.empty() || !Reference->Prefix.empty() || 312 !PreviousReference->DefaultImport.empty() || 313 !Reference->DefaultImport.empty() || Reference->Symbols.empty() || 314 PreviousReference->URL != Reference->URL) { 315 PreviousReference = Reference; 316 ++Reference; 317 continue; 318 } 319 // Merge symbols from identical imports. 320 PreviousReference->Symbols.append(Reference->Symbols); 321 PreviousReference->SymbolsMerged = true; 322 // Remove the merged import. 323 Reference = References.erase(Reference); 324 } 325 } 326 327 // Appends ``Reference`` to ``Buffer``. 328 void appendReference(std::string &Buffer, JsModuleReference &Reference) { 329 if (Reference.FormattingOff) { 330 Buffer += 331 getSourceText(Reference.Range.getBegin(), Reference.Range.getEnd()); 332 return; 333 } 334 // Sort the individual symbols within the import. 335 // E.g. `import {b, a} from 'x';` -> `import {a, b} from 'x';` 336 SmallVector<JsImportedSymbol, 1> Symbols = Reference.Symbols; 337 llvm::stable_sort( 338 Symbols, [&](const JsImportedSymbol &LHS, const JsImportedSymbol &RHS) { 339 return LHS.Symbol.compare_insensitive(RHS.Symbol) < 0; 340 }); 341 if (!Reference.SymbolsMerged && Symbols == Reference.Symbols) { 342 // Symbols didn't change, just emit the entire module reference. 343 StringRef ReferenceStmt = getSourceText(Reference.Range); 344 Buffer += ReferenceStmt; 345 return; 346 } 347 // Stitch together the module reference start... 348 Buffer += getSourceText(Reference.Range.getBegin(), Reference.SymbolsStart); 349 // ... then the references in order ... 350 if (!Symbols.empty()) { 351 Buffer += getSourceText(Symbols.front().Range); 352 for (const JsImportedSymbol &Symbol : llvm::drop_begin(Symbols)) { 353 Buffer += ","; 354 Buffer += getSourceText(Symbol.Range); 355 } 356 } 357 // ... followed by the module reference end. 358 Buffer += getSourceText(Reference.SymbolsEnd, Reference.Range.getEnd()); 359 } 360 361 // Parses module references in the given lines. Returns the module references, 362 // and a pointer to the first "main code" line if that is adjacent to the 363 // affected lines of module references, nullptr otherwise. 364 std::pair<SmallVector<JsModuleReference, 16>, AnnotatedLine *> 365 parseModuleReferences(const AdditionalKeywords &Keywords, 366 SmallVectorImpl<AnnotatedLine *> &AnnotatedLines) { 367 SmallVector<JsModuleReference, 16> References; 368 SourceLocation Start; 369 AnnotatedLine *FirstNonImportLine = nullptr; 370 bool AnyImportAffected = false; 371 bool FormattingOff = false; 372 for (auto *Line : AnnotatedLines) { 373 assert(Line->First); 374 Current = Line->First; 375 LineEnd = Line->Last; 376 // clang-format comments toggle formatting on/off. 377 // This is tracked in FormattingOff here and on JsModuleReference. 378 while (Current && Current->is(tok::comment)) { 379 StringRef CommentText = Current->TokenText.trim(); 380 if (isClangFormatOff(CommentText)) { 381 FormattingOff = true; 382 } else if (isClangFormatOn(CommentText)) { 383 FormattingOff = false; 384 // Special case: consider a trailing "clang-format on" line to be part 385 // of the module reference, so that it gets moved around together with 386 // it (as opposed to the next module reference, which might get sorted 387 // around). 388 if (!References.empty()) { 389 References.back().Range.setEnd(Current->Tok.getEndLoc()); 390 Start = Current->Tok.getEndLoc().getLocWithOffset(1); 391 } 392 } 393 // Handle all clang-format comments on a line, e.g. for an empty block. 394 Current = Current->Next; 395 } 396 skipComments(); 397 if (Start.isInvalid() || References.empty()) { 398 // After the first file level comment, consider line comments to be part 399 // of the import that immediately follows them by using the previously 400 // set Start. 401 Start = Line->First->Tok.getLocation(); 402 } 403 if (!Current) { 404 // Only comments on this line. Could be the first non-import line. 405 FirstNonImportLine = Line; 406 continue; 407 } 408 JsModuleReference Reference; 409 Reference.FormattingOff = FormattingOff; 410 Reference.Range.setBegin(Start); 411 // References w/o a URL, e.g. export {A}, groups with RELATIVE. 412 Reference.Category = JsModuleReference::ReferenceCategory::RELATIVE; 413 if (!parseModuleReference(Keywords, Reference)) { 414 if (!FirstNonImportLine) 415 FirstNonImportLine = Line; // if no comment before. 416 break; 417 } 418 FirstNonImportLine = nullptr; 419 AnyImportAffected = AnyImportAffected || Line->Affected; 420 Reference.Range.setEnd(LineEnd->Tok.getEndLoc()); 421 LLVM_DEBUG({ 422 llvm::dbgs() << "JsModuleReference: {" 423 << "formatting_off: " << Reference.FormattingOff 424 << ", is_export: " << Reference.IsExport 425 << ", cat: " << Reference.Category 426 << ", url: " << Reference.URL 427 << ", prefix: " << Reference.Prefix; 428 for (const JsImportedSymbol &Symbol : Reference.Symbols) 429 llvm::dbgs() << ", " << Symbol.Symbol << " as " << Symbol.Alias; 430 llvm::dbgs() << ", text: " << getSourceText(Reference.Range); 431 llvm::dbgs() << "}\n"; 432 }); 433 References.push_back(Reference); 434 Start = SourceLocation(); 435 } 436 // Sort imports if any import line was affected. 437 if (!AnyImportAffected) 438 References.clear(); 439 return std::make_pair(References, FirstNonImportLine); 440 } 441 442 // Parses a JavaScript/ECMAScript 6 module reference. 443 // See http://www.ecma-international.org/ecma-262/6.0/#sec-scripts-and-modules 444 // for grammar EBNF (production ModuleItem). 445 bool parseModuleReference(const AdditionalKeywords &Keywords, 446 JsModuleReference &Reference) { 447 if (!Current || !Current->isOneOf(Keywords.kw_import, tok::kw_export)) 448 return false; 449 Reference.IsExport = Current->is(tok::kw_export); 450 451 nextToken(); 452 if (Current->isStringLiteral() && !Reference.IsExport) { 453 // "import 'side-effect';" 454 Reference.Category = JsModuleReference::ReferenceCategory::SIDE_EFFECT; 455 Reference.URL = 456 Current->TokenText.substr(1, Current->TokenText.size() - 2); 457 return true; 458 } 459 460 if (!parseModuleBindings(Keywords, Reference)) 461 return false; 462 463 if (Current->is(Keywords.kw_from)) { 464 // imports have a 'from' clause, exports might not. 465 nextToken(); 466 if (!Current->isStringLiteral()) 467 return false; 468 // URL = TokenText without the quotes. 469 Reference.URL = 470 Current->TokenText.substr(1, Current->TokenText.size() - 2); 471 if (Reference.URL.startswith("..")) { 472 Reference.Category = 473 JsModuleReference::ReferenceCategory::RELATIVE_PARENT; 474 } else if (Reference.URL.startswith(".")) { 475 Reference.Category = JsModuleReference::ReferenceCategory::RELATIVE; 476 } else { 477 Reference.Category = JsModuleReference::ReferenceCategory::ABSOLUTE; 478 } 479 } 480 return true; 481 } 482 483 bool parseModuleBindings(const AdditionalKeywords &Keywords, 484 JsModuleReference &Reference) { 485 if (parseStarBinding(Keywords, Reference)) 486 return true; 487 return parseNamedBindings(Keywords, Reference); 488 } 489 490 bool parseStarBinding(const AdditionalKeywords &Keywords, 491 JsModuleReference &Reference) { 492 // * as prefix from '...'; 493 if (Current->is(Keywords.kw_type) && Current->Next && 494 Current->Next->is(tok::star)) { 495 Reference.IsTypeOnly = true; 496 nextToken(); 497 } 498 if (Current->isNot(tok::star)) 499 return false; 500 nextToken(); 501 if (Current->isNot(Keywords.kw_as)) 502 return false; 503 nextToken(); 504 if (Current->isNot(tok::identifier)) 505 return false; 506 Reference.Prefix = Current->TokenText; 507 nextToken(); 508 return true; 509 } 510 511 bool parseNamedBindings(const AdditionalKeywords &Keywords, 512 JsModuleReference &Reference) { 513 if (Current->is(Keywords.kw_type) && Current->Next && 514 Current->Next->isOneOf(tok::identifier, tok::l_brace)) { 515 Reference.IsTypeOnly = true; 516 nextToken(); 517 } 518 519 // eat a potential "import X, " prefix. 520 if (!Reference.IsExport && Current->is(tok::identifier)) { 521 Reference.DefaultImport = Current->TokenText; 522 nextToken(); 523 if (Current->is(Keywords.kw_from)) 524 return true; 525 // import X = A.B.C; 526 if (Current->is(tok::equal)) { 527 Reference.Category = JsModuleReference::ReferenceCategory::ALIAS; 528 nextToken(); 529 while (Current->is(tok::identifier)) { 530 nextToken(); 531 if (Current->is(tok::semi)) 532 return true; 533 if (!Current->is(tok::period)) 534 return false; 535 nextToken(); 536 } 537 } 538 if (Current->isNot(tok::comma)) 539 return false; 540 nextToken(); // eat comma. 541 } 542 if (Current->isNot(tok::l_brace)) 543 return false; 544 545 // {sym as alias, sym2 as ...} from '...'; 546 Reference.SymbolsStart = Current->Tok.getEndLoc(); 547 while (Current->isNot(tok::r_brace)) { 548 nextToken(); 549 if (Current->is(tok::r_brace)) 550 break; 551 bool isTypeOnly = 552 Current->is(Keywords.kw_type) && Current->Next && 553 Current->Next->isOneOf(tok::identifier, tok::kw_default); 554 if (!isTypeOnly && !Current->isOneOf(tok::identifier, tok::kw_default)) 555 return false; 556 557 JsImportedSymbol Symbol; 558 // Make sure to include any preceding comments. 559 Symbol.Range.setBegin( 560 Current->getPreviousNonComment()->Next->WhitespaceRange.getBegin()); 561 if (isTypeOnly) 562 nextToken(); 563 Symbol.Symbol = Current->TokenText; 564 nextToken(); 565 566 if (Current->is(Keywords.kw_as)) { 567 nextToken(); 568 if (!Current->isOneOf(tok::identifier, tok::kw_default)) 569 return false; 570 Symbol.Alias = Current->TokenText; 571 nextToken(); 572 } 573 Symbol.Range.setEnd(Current->Tok.getLocation()); 574 Reference.Symbols.push_back(Symbol); 575 576 if (!Current->isOneOf(tok::r_brace, tok::comma)) 577 return false; 578 } 579 Reference.SymbolsEnd = Current->Tok.getLocation(); 580 // For named imports with a trailing comma ("import {X,}"), consider the 581 // comma to be the end of the import list, so that it doesn't get removed. 582 if (Current->Previous->is(tok::comma)) 583 Reference.SymbolsEnd = Current->Previous->Tok.getLocation(); 584 nextToken(); // consume r_brace 585 return true; 586 } 587 }; 588 589 tooling::Replacements sortJavaScriptImports(const FormatStyle &Style, 590 StringRef Code, 591 ArrayRef<tooling::Range> Ranges, 592 StringRef FileName) { 593 // FIXME: Cursor support. 594 auto Env = Environment::make(Code, FileName, Ranges); 595 if (!Env) 596 return {}; 597 return JavaScriptImportSorter(*Env, Style).process().first; 598 } 599 600 } // end namespace format 601 } // end namespace clang 602