clang/utils/TableGen/ClangASTPropertiesEmitter.cpp

   1 //=== ClangASTPropsEmitter.cpp - Generate Clang AST properties --*- 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 // This tablegen backend emits code for working with Clang AST properties.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "ASTTableGen.h"
  14 #include "TableGenBackends.h"
  15
  16 #include "llvm/ADT/STLExtras.h"
  17 #include "llvm/ADT/Twine.h"
  18 #include "llvm/TableGen/Error.h"
  19 #include "llvm/TableGen/Record.h"
  20 #include "llvm/TableGen/TableGenBackend.h"
  21 #include <cctype>
  22 #include <map>
  23 #include <optional>
  24 #include <set>
  25 #include <string>
  26 using namespace llvm;
  27 using namespace clang;
  28 using namespace clang::tblgen;
  29
  30 static StringRef getReaderResultType(TypeNode _) { return "QualType"; }
  31
  32 namespace {
  33
  34 struct ReaderWriterInfo {
  35   bool IsReader;
  36
  37   /// The name of the node hierarchy.  Not actually sensitive to IsReader,
  38   /// but useful to cache here anyway.
  39   StringRef HierarchyName;
  40
  41   /// The suffix on classes: Reader/Writer
  42   StringRef ClassSuffix;
  43
  44   /// The base name of methods: read/write
  45   StringRef MethodPrefix;
  46
  47   /// The name of the property helper member: R/W
  48   StringRef HelperVariable;
  49
  50   /// The result type of methods on the class.
  51   StringRef ResultType;
  52
  53   template <class NodeClass>
  54   static ReaderWriterInfo forReader() {
  55     return ReaderWriterInfo{
  56       true,
  57       NodeClass::getASTHierarchyName(),
  58       "Reader",
  59       "read",
  60       "R",
  61       getReaderResultType(NodeClass())
  62     };
  63   }
  64
  65   template <class NodeClass>
  66   static ReaderWriterInfo forWriter() {
  67     return ReaderWriterInfo{
  68       false,
  69       NodeClass::getASTHierarchyName(),
  70       "Writer",
  71       "write",
  72       "W",
  73       "void"
  74     };
  75   }
  76 };
  77
  78 struct NodeInfo {
  79   std::vector<Property> Properties;
  80   CreationRule Creator = nullptr;
  81   OverrideRule Override = nullptr;
  82   ReadHelperRule ReadHelper = nullptr;
  83 };
  84
  85 struct CasedTypeInfo {
  86   TypeKindRule KindRule;
  87   std::vector<TypeCase> Cases;
  88 };
  89
  90 class ASTPropsEmitter {
  91         raw_ostream &Out;
  92         RecordKeeper &Records;
  93         std::map<HasProperties, NodeInfo> NodeInfos;
  94   std::vector<PropertyType> AllPropertyTypes;
  95   std::map<PropertyType, CasedTypeInfo> CasedTypeInfos;
  96
  97 public:
  98         ASTPropsEmitter(RecordKeeper &records, raw_ostream &out)
  99                 : Out(out), Records(records) {
 100
 101                 // Find all the properties.
 102                 for (Property property :
 103            records.getAllDerivedDefinitions(PropertyClassName)) {
 104                         HasProperties node = property.getClass();
 105                         NodeInfos[node].Properties.push_back(property);
 106                 }
 107
 108     // Find all the creation rules.
 109     for (CreationRule creationRule :
 110            records.getAllDerivedDefinitions(CreationRuleClassName)) {
 111       HasProperties node = creationRule.getClass();
 112
 113       auto &info = NodeInfos[node];
 114       if (info.Creator) {
 115         PrintFatalError(creationRule.getLoc(),
 116                         "multiple creator rules for \"" + node.getName()
 117                           + "\"");
 118       }
 119       info.Creator = creationRule;
 120     }
 121
 122     // Find all the override rules.
 123     for (OverrideRule overrideRule :
 124            records.getAllDerivedDefinitions(OverrideRuleClassName)) {
 125       HasProperties node = overrideRule.getClass();
 126
 127       auto &info = NodeInfos[node];
 128       if (info.Override) {
 129         PrintFatalError(overrideRule.getLoc(),
 130                         "multiple override rules for \"" + node.getName()
 131                           + "\"");
 132       }
 133       info.Override = overrideRule;
 134     }
 135
 136     // Find all the write helper rules.
 137     for (ReadHelperRule helperRule :
 138            records.getAllDerivedDefinitions(ReadHelperRuleClassName)) {
 139       HasProperties node = helperRule.getClass();
 140
 141       auto &info = NodeInfos[node];
 142       if (info.ReadHelper) {
 143         PrintFatalError(helperRule.getLoc(),
 144                         "multiple write helper rules for \"" + node.getName()
 145                           + "\"");
 146       }
 147       info.ReadHelper = helperRule;
 148     }
 149
 150     // Find all the concrete property types.
 151     for (PropertyType type :
 152            records.getAllDerivedDefinitions(PropertyTypeClassName)) {
 153       // Ignore generic specializations; they're generally not useful when
 154       // emitting basic emitters etc.
 155       if (type.isGenericSpecialization()) continue;
 156
 157       AllPropertyTypes.push_back(type);
 158     }
 159
 160     // Find all the type kind rules.
 161     for (TypeKindRule kindRule :
 162            records.getAllDerivedDefinitions(TypeKindClassName)) {
 163       PropertyType type = kindRule.getParentType();
 164       auto &info = CasedTypeInfos[type];
 165       if (info.KindRule) {
 166         PrintFatalError(kindRule.getLoc(),
 167                         "multiple kind rules for \""
 168                            + type.getCXXTypeName() + "\"");
 169       }
 170       info.KindRule = kindRule;
 171     }
 172
 173     // Find all the type cases.
 174     for (TypeCase typeCase :
 175            records.getAllDerivedDefinitions(TypeCaseClassName)) {
 176       CasedTypeInfos[typeCase.getParentType()].Cases.push_back(typeCase);
 177     }
 178
 179     Validator(*this).validate();
 180         }
 181
 182   void visitAllProperties(HasProperties derived, const NodeInfo &derivedInfo,
 183                           function_ref<void (Property)> visit) {
 184     std::set<StringRef> ignoredProperties;
 185
 186     auto overrideRule = derivedInfo.Override;
 187     if (overrideRule) {
 188       auto list = overrideRule.getIgnoredProperties();
 189       ignoredProperties.insert(list.begin(), list.end());
 190     }
 191
 192     // TODO: we should sort the properties in various ways
 193     //   - put arrays at the end to enable abbreviations
 194     //   - put conditional properties after properties used in the condition
 195
 196     visitAllNodesWithInfo(derived, derivedInfo,
 197                           [&](HasProperties node, const NodeInfo &info) {
 198       for (Property prop : info.Properties) {
 199         if (ignoredProperties.count(prop.getName()))
 200           continue;
 201
 202         visit(prop);
 203       }
 204     });
 205   }
 206
 207   void visitAllNodesWithInfo(HasProperties derivedNode,
 208                              const NodeInfo &derivedNodeInfo,
 209                              llvm::function_ref<void (HasProperties node,
 210                                                       const NodeInfo &info)>
 211                                visit) {
 212     visit(derivedNode, derivedNodeInfo);
 213
 214     // Also walk the bases if appropriate.
 215     if (ASTNode base = derivedNode.getAs<ASTNode>()) {
 216       for (base = base.getBase(); base; base = base.getBase()) {
 217         auto it = NodeInfos.find(base);
 218
 219         // Ignore intermediate nodes that don't add interesting properties.
 220         if (it == NodeInfos.end()) continue;
 221         auto &baseInfo = it->second;
 222
 223         visit(base, baseInfo);
 224       }
 225     }
 226   }
 227
 228   template <class NodeClass>
 229   void emitNodeReaderClass() {
 230     auto info = ReaderWriterInfo::forReader<NodeClass>();
 231     emitNodeReaderWriterClass<NodeClass>(info);
 232   }
 233
 234   template <class NodeClass>
 235   void emitNodeWriterClass() {
 236     auto info = ReaderWriterInfo::forWriter<NodeClass>();
 237     emitNodeReaderWriterClass<NodeClass>(info);
 238   }
 239
 240   template <class NodeClass>
 241   void emitNodeReaderWriterClass(const ReaderWriterInfo &info);
 242
 243   template <class NodeClass>
 244   void emitNodeReaderWriterMethod(NodeClass node,
 245                                   const ReaderWriterInfo &info);
 246
 247   void emitPropertiedReaderWriterBody(HasProperties node,
 248                                       const ReaderWriterInfo &info);
 249
 250   void emitReadOfProperty(StringRef readerName, Property property);
 251   void emitReadOfProperty(StringRef readerName, StringRef name,
 252                           PropertyType type, StringRef condition = "");
 253
 254   void emitWriteOfProperty(StringRef writerName, Property property);
 255   void emitWriteOfProperty(StringRef writerName, StringRef name,
 256                            PropertyType type, StringRef readCode,
 257                            StringRef condition = "");
 258
 259   void emitBasicReaderWriterFile(const ReaderWriterInfo &info);
 260   void emitDispatcherTemplate(const ReaderWriterInfo &info);
 261   void emitPackUnpackOptionalTemplate(const ReaderWriterInfo &info);
 262   void emitBasicReaderWriterTemplate(const ReaderWriterInfo &info);
 263
 264   void emitCasedReaderWriterMethodBody(PropertyType type,
 265                                        const CasedTypeInfo &typeCases,
 266                                        const ReaderWriterInfo &info);
 267
 268 private:
 269   class Validator {
 270     ASTPropsEmitter &Emitter;
 271     std::set<HasProperties> ValidatedNodes;
 272
 273   public:
 274     Validator(ASTPropsEmitter &emitter) : Emitter(emitter) {}
 275     void validate();
 276
 277   private:
 278     void validateNode(HasProperties node, const NodeInfo &nodeInfo);
 279     void validateType(PropertyType type, WrappedRecord context);
 280   };
 281 };
 282
 283 } // end anonymous namespace
 284
 285 void ASTPropsEmitter::Validator::validate() {
 286   for (auto &entry : Emitter.NodeInfos) {
 287     validateNode(entry.first, entry.second);
 288   }
 289
 290   if (ErrorsPrinted > 0) {
 291     PrintFatalError("property validation failed");
 292   }
 293 }
 294
 295 void ASTPropsEmitter::Validator::validateNode(HasProperties derivedNode,
 296                                               const NodeInfo &derivedNodeInfo) {
 297   if (!ValidatedNodes.insert(derivedNode).second) return;
 298
 299   // A map from property name to property.
 300   std::map<StringRef, Property> allProperties;
 301
 302   Emitter.visitAllNodesWithInfo(derivedNode, derivedNodeInfo,
 303                                 [&](HasProperties node,
 304                                     const NodeInfo &nodeInfo) {
 305     for (Property property : nodeInfo.Properties) {
 306       validateType(property.getType(), property);
 307
 308       auto result = allProperties.insert(
 309                       std::make_pair(property.getName(), property));
 310
 311       // Diagnose non-unique properties.
 312       if (!result.second) {
 313         // The existing property is more likely to be associated with a
 314         // derived node, so use it as the error.
 315         Property existingProperty = result.first->second;
 316         PrintError(existingProperty.getLoc(),
 317                    "multiple properties named \"" + property.getName()
 318                       + "\" in hierarchy of " + derivedNode.getName());
 319         PrintNote(property.getLoc(), "existing property");
 320       }
 321     }
 322   });
 323 }
 324
 325 void ASTPropsEmitter::Validator::validateType(PropertyType type,
 326                                               WrappedRecord context) {
 327   if (!type.isGenericSpecialization()) {
 328     if (type.getCXXTypeName() == "") {
 329       PrintError(type.getLoc(),
 330                  "type is not generic but has no C++ type name");
 331       if (context) PrintNote(context.getLoc(), "type used here");
 332     }
 333   } else if (auto eltType = type.getArrayElementType()) {
 334     validateType(eltType, context);
 335   } else if (auto valueType = type.getOptionalElementType()) {
 336     validateType(valueType, context);
 337
 338     if (valueType.getPackOptionalCode().empty()) {
 339       PrintError(valueType.getLoc(),
 340                  "type doesn't provide optional-packing code");
 341       if (context) PrintNote(context.getLoc(), "type used here");
 342     } else if (valueType.getUnpackOptionalCode().empty()) {
 343       PrintError(valueType.getLoc(),
 344                  "type doesn't provide optional-unpacking code");
 345       if (context) PrintNote(context.getLoc(), "type used here");
 346     }
 347   } else {
 348     PrintError(type.getLoc(), "unknown generic property type");
 349     if (context) PrintNote(context.getLoc(), "type used here");
 350   }
 351 }
 352
 353 /****************************************************************************/
 354 /**************************** AST READER/WRITERS ****************************/
 355 /****************************************************************************/
 356
 357 template <class NodeClass>
 358 void ASTPropsEmitter::emitNodeReaderWriterClass(const ReaderWriterInfo &info) {
 359   StringRef suffix = info.ClassSuffix;
 360   StringRef var = info.HelperVariable;
 361
 362   // Enter the class declaration.
 363   Out << "template <class Property" << suffix << ">\n"
 364          "class Abstract" << info.HierarchyName << suffix << " {\n"
 365          "public:\n"
 366          "  Property" << suffix << " &" << var << ";\n\n";
 367
 368   // Emit the constructor.
 369   Out << "  Abstract" << info.HierarchyName << suffix
 370                       << "(Property" << suffix << " &" << var << ") : "
 371                       << var << "(" << var << ") {}\n\n";
 372
 373   // Emit a method that dispatches on a kind to the appropriate node-specific
 374   // method.
 375   Out << "  " << info.ResultType << " " << info.MethodPrefix << "(";
 376   if (info.IsReader)
 377     Out       << NodeClass::getASTIdTypeName() << " kind";
 378   else
 379     Out       << "const " << info.HierarchyName << " *node";
 380   Out         << ") {\n"
 381          "    switch (";
 382   if (info.IsReader)
 383     Out         << "kind";
 384   else
 385     Out         << "node->" << NodeClass::getASTIdAccessorName() << "()";
 386   Out           << ") {\n";
 387   visitASTNodeHierarchy<NodeClass>(Records, [&](NodeClass node, NodeClass _) {
 388     if (node.isAbstract()) return;
 389     Out << "    case " << info.HierarchyName << "::" << node.getId() << ":\n"
 390            "      return " << info.MethodPrefix << node.getClassName() << "(";
 391     if (!info.IsReader)
 392       Out                  << "static_cast<const " << node.getClassName()
 393                            << " *>(node)";
 394     Out                    << ");\n";
 395   });
 396   Out << "    }\n"
 397          "    llvm_unreachable(\"bad kind\");\n"
 398          "  }\n\n";
 399
 400   // Emit node-specific methods for all the concrete nodes.
 401   visitASTNodeHierarchy<NodeClass>(Records,
 402                                    [&](NodeClass node, NodeClass base) {
 403     if (node.isAbstract()) return;
 404     emitNodeReaderWriterMethod(node, info);
 405   });
 406
 407   // Finish the class.
 408   Out << "};\n\n";
 409 }
 410
 411 /// Emit a reader method for the given concrete AST node class.
 412 template <class NodeClass>
 413 void ASTPropsEmitter::emitNodeReaderWriterMethod(NodeClass node,
 414                                            const ReaderWriterInfo &info) {
 415   // Declare and start the method.
 416   Out << "  " << info.ResultType << " "
 417               << info.MethodPrefix << node.getClassName() << "(";
 418   if (!info.IsReader)
 419     Out <<       "const " << node.getClassName() << " *node";
 420   Out <<         ") {\n";
 421   if (info.IsReader)
 422     Out << "    auto &ctx = " << info.HelperVariable << ".getASTContext();\n";
 423
 424   emitPropertiedReaderWriterBody(node, info);
 425
 426   // Finish the method declaration.
 427   Out << "  }\n\n";
 428 }
 429
 430 void ASTPropsEmitter::emitPropertiedReaderWriterBody(HasProperties node,
 431                                                const ReaderWriterInfo &info) {
 432   // Find the information for this node.
 433   auto it = NodeInfos.find(node);
 434   if (it == NodeInfos.end())
 435     PrintFatalError(node.getLoc(),
 436                     "no information about how to deserialize \""
 437                       + node.getName() + "\"");
 438   auto &nodeInfo = it->second;
 439
 440   StringRef creationCode;
 441   if (info.IsReader) {
 442     // We should have a creation rule.
 443     if (!nodeInfo.Creator)
 444       PrintFatalError(node.getLoc(),
 445                       "no " CreationRuleClassName " for \""
 446                         + node.getName() + "\"");
 447
 448     creationCode = nodeInfo.Creator.getCreationCode();
 449   }
 450
 451   // Emit the ReadHelper code, if present.
 452   if (!info.IsReader && nodeInfo.ReadHelper) {
 453     Out << "    " << nodeInfo.ReadHelper.getHelperCode() << "\n";
 454   }
 455
 456   // Emit code to read all the properties.
 457   visitAllProperties(node, nodeInfo, [&](Property prop) {
 458     // Verify that the creation code refers to this property.
 459     if (info.IsReader && !creationCode.contains(prop.getName()))
 460       PrintFatalError(nodeInfo.Creator.getLoc(),
 461                       "creation code for " + node.getName()
 462                         + " doesn't refer to property \""
 463                         + prop.getName() + "\"");
 464
 465     // Emit code to read or write this property.
 466     if (info.IsReader)
 467       emitReadOfProperty(info.HelperVariable, prop);
 468     else
 469       emitWriteOfProperty(info.HelperVariable, prop);
 470   });
 471
 472   // Emit the final creation code.
 473   if (info.IsReader)
 474     Out << "    " << creationCode << "\n";
 475 }
 476
 477 static void emitBasicReaderWriterMethodSuffix(raw_ostream &out,
 478                                               PropertyType type,
 479                                               bool isForRead) {
 480   if (!type.isGenericSpecialization()) {
 481     out << type.getAbstractTypeName();
 482   } else if (auto eltType = type.getArrayElementType()) {
 483     out << "Array";
 484     // We only include an explicit template argument for reads so that
 485     // we don't cause spurious const mismatches.
 486     if (isForRead) {
 487       out << "<";
 488       eltType.emitCXXValueTypeName(isForRead, out);
 489       out << ">";
 490     }
 491   } else if (auto valueType = type.getOptionalElementType()) {
 492     out << "Optional";
 493     // We only include an explicit template argument for reads so that
 494     // we don't cause spurious const mismatches.
 495     if (isForRead) {
 496       out << "<";
 497       valueType.emitCXXValueTypeName(isForRead, out);
 498       out << ">";
 499     }
 500   } else {
 501     PrintFatalError(type.getLoc(), "unexpected generic property type");
 502   }
 503 }
 504
 505 /// Emit code to read the given property in a node-reader method.
 506 void ASTPropsEmitter::emitReadOfProperty(StringRef readerName,
 507                                          Property property) {
 508   emitReadOfProperty(readerName, property.getName(), property.getType(),
 509                      property.getCondition());
 510 }
 511
 512 void ASTPropsEmitter::emitReadOfProperty(StringRef readerName,
 513                                          StringRef name,
 514                                          PropertyType type,
 515                                          StringRef condition) {
 516   // Declare all the necessary buffers.
 517   auto bufferTypes = type.getBufferElementTypes();
 518   for (size_t i = 0, e = bufferTypes.size(); i != e; ++i) {
 519     Out << "    llvm::SmallVector<";
 520     PropertyType(bufferTypes[i]).emitCXXValueTypeName(/*for read*/ true, Out);
 521     Out << ", 8> " << name << "_buffer_" << i << ";\n";
 522   }
 523
 524   //   T prop = R.find("prop").read##ValueType(buffers...);
 525   // We intentionally ignore shouldPassByReference here: we're going to
 526   // get a pr-value back from read(), and we should be able to forward
 527   // that in the creation rule.
 528   Out << "    ";
 529   if (!condition.empty())
 530     Out << "std::optional<";
 531   type.emitCXXValueTypeName(true, Out);
 532   if (!condition.empty()) Out << ">";
 533   Out << " " << name;
 534
 535   if (condition.empty()) {
 536     Out << " = ";
 537   } else {
 538     Out << ";\n"
 539            "    if (" << condition << ") {\n"
 540            "      " << name << ".emplace(";
 541   }
 542
 543   Out << readerName << ".find(\"" << name << "\")."
 544       << (type.isGenericSpecialization() ? "template " : "") << "read";
 545   emitBasicReaderWriterMethodSuffix(Out, type, /*for read*/ true);
 546   Out << "(";
 547   for (size_t i = 0, e = bufferTypes.size(); i != e; ++i) {
 548     Out << (i > 0 ? ", " : "") << name << "_buffer_" << i;
 549   }
 550   Out << ")";
 551
 552   if (condition.empty()) {
 553     Out << ";\n";
 554   } else {
 555     Out << ");\n"
 556            "    }\n";
 557   }
 558 }
 559
 560 /// Emit code to write the given property in a node-writer method.
 561 void ASTPropsEmitter::emitWriteOfProperty(StringRef writerName,
 562                                           Property property) {
 563   emitWriteOfProperty(writerName, property.getName(), property.getType(),
 564                       property.getReadCode(), property.getCondition());
 565 }
 566
 567 void ASTPropsEmitter::emitWriteOfProperty(StringRef writerName,
 568                                           StringRef name,
 569                                           PropertyType type,
 570                                           StringRef readCode,
 571                                           StringRef condition) {
 572   if (!condition.empty()) {
 573     Out << "    if (" << condition << ") {\n";
 574   }
 575
 576   // Focus down to the property:
 577   //   T prop = <READ>;
 578   //   W.find("prop").write##ValueType(prop);
 579   Out << "    ";
 580   type.emitCXXValueTypeName(false, Out);
 581   Out << " " << name << " = (" << readCode << ");\n"
 582          "    " << writerName << ".find(\"" << name << "\").write";
 583   emitBasicReaderWriterMethodSuffix(Out, type, /*for read*/ false);
 584   Out << "(" << name << ");\n";
 585
 586   if (!condition.empty()) {
 587     Out << "    }\n";
 588   }
 589 }
 590
 591 /// Emit an .inc file that defines the AbstractFooReader class
 592 /// for the given AST class hierarchy.
 593 template <class NodeClass>
 594 static void emitASTReader(RecordKeeper &records, raw_ostream &out,
 595                           StringRef description) {
 596   emitSourceFileHeader(description, out);
 597
 598   ASTPropsEmitter(records, out).emitNodeReaderClass<NodeClass>();
 599 }
 600
 601 void clang::EmitClangTypeReader(RecordKeeper &records, raw_ostream &out) {
 602   emitASTReader<TypeNode>(records, out, "A CRTP reader for Clang Type nodes");
 603 }
 604
 605 /// Emit an .inc file that defines the AbstractFooWriter class
 606 /// for the given AST class hierarchy.
 607 template <class NodeClass>
 608 static void emitASTWriter(RecordKeeper &records, raw_ostream &out,
 609                           StringRef description) {
 610   emitSourceFileHeader(description, out);
 611
 612   ASTPropsEmitter(records, out).emitNodeWriterClass<NodeClass>();
 613 }
 614
 615 void clang::EmitClangTypeWriter(RecordKeeper &records, raw_ostream &out) {
 616   emitASTWriter<TypeNode>(records, out, "A CRTP writer for Clang Type nodes");
 617 }
 618
 619 /****************************************************************************/
 620 /*************************** BASIC READER/WRITERS ***************************/
 621 /****************************************************************************/
 622
 623 void
 624 ASTPropsEmitter::emitDispatcherTemplate(const ReaderWriterInfo &info) {
 625   // Declare the {Read,Write}Dispatcher template.
 626   StringRef dispatcherPrefix = (info.IsReader ? "Read" : "Write");
 627   Out << "template <class ValueType>\n"
 628          "struct " << dispatcherPrefix << "Dispatcher;\n";
 629
 630   // Declare a specific specialization of the dispatcher template.
 631   auto declareSpecialization =
 632     [&](StringRef specializationParameters,
 633         const Twine &cxxTypeName,
 634         StringRef methodSuffix) {
 635     StringRef var = info.HelperVariable;
 636     Out << "template " << specializationParameters << "\n"
 637            "struct " << dispatcherPrefix << "Dispatcher<"
 638                      << cxxTypeName << "> {\n";
 639     Out << "  template <class Basic" << info.ClassSuffix << ", class... Args>\n"
 640            "  static " << (info.IsReader ? cxxTypeName : "void") << " "
 641                        << info.MethodPrefix
 642                        << "(Basic" << info.ClassSuffix << " &" << var
 643                        << ", Args &&... args) {\n"
 644            "    return " << var << "."
 645                          << info.MethodPrefix << methodSuffix
 646                          << "(std::forward<Args>(args)...);\n"
 647            "  }\n"
 648            "};\n";
 649   };
 650
 651   // Declare explicit specializations for each of the concrete types.
 652   for (PropertyType type : AllPropertyTypes) {
 653     declareSpecialization("<>",
 654                           type.getCXXTypeName(),
 655                           type.getAbstractTypeName());
 656     // Also declare a specialization for the const type when appropriate.
 657     if (!info.IsReader && type.isConstWhenWriting()) {
 658       declareSpecialization("<>",
 659                             "const " + type.getCXXTypeName(),
 660                             type.getAbstractTypeName());
 661     }
 662   }
 663   // Declare partial specializations for ArrayRef and Optional.
 664   declareSpecialization("<class T>",
 665                         "llvm::ArrayRef<T>",
 666                         "Array");
 667   declareSpecialization("<class T>", "std::optional<T>", "Optional");
 668   Out << "\n";
 669 }
 670
 671 void
 672 ASTPropsEmitter::emitPackUnpackOptionalTemplate(const ReaderWriterInfo &info) {
 673   StringRef classPrefix = (info.IsReader ? "Unpack" : "Pack");
 674   StringRef methodName = (info.IsReader ? "unpack" : "pack");
 675
 676   // Declare the {Pack,Unpack}OptionalValue template.
 677   Out << "template <class ValueType>\n"
 678          "struct " << classPrefix << "OptionalValue;\n";
 679
 680   auto declareSpecialization = [&](const Twine &typeName, StringRef code) {
 681     Out << "template <>\n"
 682            "struct "
 683         << classPrefix << "OptionalValue<" << typeName
 684         << "> {\n"
 685            "  static "
 686         << (info.IsReader ? "std::optional<" : "") << typeName
 687         << (info.IsReader ? "> " : " ") << methodName << "("
 688         << (info.IsReader ? "" : "std::optional<") << typeName
 689         << (info.IsReader ? "" : ">")
 690         << " value) {\n"
 691            "    return "
 692         << code
 693         << ";\n"
 694            "  }\n"
 695            "};\n";
 696   };
 697
 698   for (PropertyType type : AllPropertyTypes) {
 699     StringRef code = (info.IsReader ? type.getUnpackOptionalCode()
 700                                     : type.getPackOptionalCode());
 701     if (code.empty()) continue;
 702
 703     StringRef typeName = type.getCXXTypeName();
 704     declareSpecialization(typeName, code);
 705     if (type.isConstWhenWriting() && !info.IsReader)
 706       declareSpecialization("const " + typeName, code);
 707   }
 708   Out << "\n";
 709 }
 710
 711 void
 712 ASTPropsEmitter::emitBasicReaderWriterTemplate(const ReaderWriterInfo &info) {
 713   // Emit the Basic{Reader,Writer}Base template.
 714   Out << "template <class Impl>\n"
 715          "class Basic" << info.ClassSuffix << "Base {\n";
 716   Out << "  ASTContext &C;\n";
 717   Out << "protected:\n"
 718          "  Basic"
 719       << info.ClassSuffix << "Base" << ("(ASTContext &ctx) : C(ctx)")
 720       << " {}\n"
 721          "public:\n";
 722   Out << "  ASTContext &getASTContext() { return C; }\n";
 723   Out << "  Impl &asImpl() { return static_cast<Impl&>(*this); }\n";
 724
 725   auto enterReaderWriterMethod = [&](StringRef cxxTypeName,
 726                                      StringRef abstractTypeName,
 727                                      bool shouldPassByReference,
 728                                      bool constWhenWriting,
 729                                      StringRef paramName) {
 730     Out << "  " << (info.IsReader ? cxxTypeName : "void")
 731                 << " " << info.MethodPrefix << abstractTypeName << "(";
 732     if (!info.IsReader)
 733       Out       << (shouldPassByReference || constWhenWriting ? "const " : "")
 734                 << cxxTypeName
 735                 << (shouldPassByReference ? " &" : "") << " " << paramName;
 736     Out         << ") {\n";
 737   };
 738
 739   // Emit {read,write}ValueType methods for all the enum and subclass types
 740   // that default to using the integer/base-class implementations.
 741   for (PropertyType type : AllPropertyTypes) {
 742     auto enterMethod = [&](StringRef paramName) {
 743       enterReaderWriterMethod(type.getCXXTypeName(),
 744                               type.getAbstractTypeName(),
 745                               type.shouldPassByReference(),
 746                               type.isConstWhenWriting(),
 747                               paramName);
 748     };
 749     auto exitMethod = [&] {
 750       Out << "  }\n";
 751     };
 752
 753     // Handled cased types.
 754     auto casedIter = CasedTypeInfos.find(type);
 755     if (casedIter != CasedTypeInfos.end()) {
 756       enterMethod("node");
 757       emitCasedReaderWriterMethodBody(type, casedIter->second, info);
 758       exitMethod();
 759
 760     } else if (type.isEnum()) {
 761       enterMethod("value");
 762       if (info.IsReader)
 763         Out << "    return asImpl().template readEnum<"
 764             <<         type.getCXXTypeName() << ">();\n";
 765       else
 766         Out << "    asImpl().writeEnum(value);\n";
 767       exitMethod();
 768
 769     } else if (PropertyType superclass = type.getSuperclassType()) {
 770       enterMethod("value");
 771       if (info.IsReader)
 772         Out << "    return cast_or_null<" << type.getSubclassClassName()
 773                                           << ">(asImpl().read"
 774                                           << superclass.getAbstractTypeName()
 775                                           << "());\n";
 776       else
 777         Out << "    asImpl().write" << superclass.getAbstractTypeName()
 778                                     << "(value);\n";
 779       exitMethod();
 780
 781     } else {
 782       // The other types can't be handled as trivially.
 783     }
 784   }
 785   Out << "};\n\n";
 786 }
 787
 788 void ASTPropsEmitter::emitCasedReaderWriterMethodBody(PropertyType type,
 789                                              const CasedTypeInfo &typeCases,
 790                                              const ReaderWriterInfo &info) {
 791   if (typeCases.Cases.empty()) {
 792     assert(typeCases.KindRule);
 793     PrintFatalError(typeCases.KindRule.getLoc(),
 794                     "no cases found for \"" + type.getCXXTypeName() + "\"");
 795   }
 796   if (!typeCases.KindRule) {
 797     assert(!typeCases.Cases.empty());
 798     PrintFatalError(typeCases.Cases.front().getLoc(),
 799                     "no kind rule for \"" + type.getCXXTypeName() + "\"");
 800   }
 801
 802   auto var = info.HelperVariable;
 803   std::string subvar = ("sub" + var).str();
 804
 805   // Bind `ctx` for readers.
 806   if (info.IsReader)
 807     Out << "    auto &ctx = asImpl().getASTContext();\n";
 808
 809   // Start an object.
 810   Out << "    auto &&" << subvar << " = asImpl()."
 811                        << info.MethodPrefix << "Object();\n";
 812
 813   // Read/write the kind property;
 814   TypeKindRule kindRule = typeCases.KindRule;
 815   StringRef kindProperty = kindRule.getKindPropertyName();
 816   PropertyType kindType = kindRule.getKindType();
 817   if (info.IsReader) {
 818     emitReadOfProperty(subvar, kindProperty, kindType);
 819   } else {
 820     // Write the property.  Note that this will implicitly read the
 821     // kind into a local variable with the right name.
 822     emitWriteOfProperty(subvar, kindProperty, kindType,
 823                         kindRule.getReadCode());
 824   }
 825
 826   // Prepare a ReaderWriterInfo with a helper variable that will use
 827   // the sub-reader/writer.
 828   ReaderWriterInfo subInfo = info;
 829   subInfo.HelperVariable = subvar;
 830
 831   // Switch on the kind.
 832   Out << "    switch (" << kindProperty << ") {\n";
 833   for (TypeCase typeCase : typeCases.Cases) {
 834     Out << "    case " << type.getCXXTypeName() << "::"
 835                        << typeCase.getCaseName() << ": {\n";
 836     emitPropertiedReaderWriterBody(typeCase, subInfo);
 837     if (!info.IsReader)
 838       Out << "    return;\n";
 839     Out << "    }\n\n";
 840   }
 841   Out << "    }\n"
 842          "    llvm_unreachable(\"bad " << kindType.getCXXTypeName()
 843                                        << "\");\n";
 844 }
 845
 846 void ASTPropsEmitter::emitBasicReaderWriterFile(const ReaderWriterInfo &info) {
 847   emitDispatcherTemplate(info);
 848   emitPackUnpackOptionalTemplate(info);
 849   emitBasicReaderWriterTemplate(info);
 850 }
 851
 852 /// Emit an .inc file that defines some helper classes for reading
 853 /// basic values.
 854 void clang::EmitClangBasicReader(RecordKeeper &records, raw_ostream &out) {
 855   emitSourceFileHeader("Helper classes for BasicReaders", out);
 856
 857   // Use any property, we won't be using those properties.
 858   auto info = ReaderWriterInfo::forReader<TypeNode>();
 859   ASTPropsEmitter(records, out).emitBasicReaderWriterFile(info);
 860 }
 861
 862 /// Emit an .inc file that defines some helper classes for writing
 863 /// basic values.
 864 void clang::EmitClangBasicWriter(RecordKeeper &records, raw_ostream &out) {
 865   emitSourceFileHeader("Helper classes for BasicWriters", out);
 866
 867   // Use any property, we won't be using those properties.
 868   auto info = ReaderWriterInfo::forWriter<TypeNode>();
 869   ASTPropsEmitter(records, out).emitBasicReaderWriterFile(info);
 870 }