clang/lib/Format/MacroExpander.cpp

   1 //===--- MacroExpander.cpp - Format C++ code --------------------*- 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 contains the implementation of MacroExpander, which handles macro
  11 /// configuration and expansion while formatting.
  12 ///
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "Macros.h"
  16
  17 #include "Encoding.h"
  18 #include "FormatToken.h"
  19 #include "FormatTokenLexer.h"
  20 #include "clang/Basic/TokenKinds.h"
  21 #include "clang/Format/Format.h"
  22 #include "clang/Lex/HeaderSearch.h"
  23 #include "clang/Lex/HeaderSearchOptions.h"
  24 #include "clang/Lex/Lexer.h"
  25 #include "clang/Lex/ModuleLoader.h"
  26 #include "clang/Lex/Preprocessor.h"
  27 #include "clang/Lex/PreprocessorOptions.h"
  28 #include "llvm/ADT/StringSet.h"
  29 #include "llvm/Support/ErrorHandling.h"
  30
  31 namespace clang {
  32 namespace format {
  33
  34 struct MacroExpander::Definition {
  35   StringRef Name;
  36   SmallVector<FormatToken *, 8> Params;
  37   SmallVector<FormatToken *, 8> Body;
  38
  39   // Map from each argument's name to its position in the argument list.
  40   // With "M(x, y) x + y":
  41   //   x -> 0
  42   //   y -> 1
  43   llvm::StringMap<size_t> ArgMap;
  44
  45   bool ObjectLike = true;
  46 };
  47
  48 class MacroExpander::DefinitionParser {
  49 public:
  50   DefinitionParser(ArrayRef<FormatToken *> Tokens) : Tokens(Tokens) {
  51     assert(!Tokens.empty());
  52     Current = Tokens[0];
  53   }
  54
  55   // Parse the token stream and return the corresponding Definition object.
  56   // Returns an empty definition object with a null-Name on error.
  57   MacroExpander::Definition parse() {
  58     if (!Current->is(tok::identifier))
  59       return {};
  60     Def.Name = Current->TokenText;
  61     nextToken();
  62     if (Current->is(tok::l_paren)) {
  63       Def.ObjectLike = false;
  64       if (!parseParams())
  65         return {};
  66     }
  67     if (!parseExpansion())
  68       return {};
  69
  70     return Def;
  71   }
  72
  73 private:
  74   bool parseParams() {
  75     assert(Current->is(tok::l_paren));
  76     nextToken();
  77     while (Current->is(tok::identifier)) {
  78       Def.Params.push_back(Current);
  79       Def.ArgMap[Def.Params.back()->TokenText] = Def.Params.size() - 1;
  80       nextToken();
  81       if (Current->isNot(tok::comma))
  82         break;
  83       nextToken();
  84     }
  85     if (Current->isNot(tok::r_paren))
  86       return false;
  87     nextToken();
  88     return true;
  89   }
  90
  91   bool parseExpansion() {
  92     if (!Current->isOneOf(tok::equal, tok::eof))
  93       return false;
  94     if (Current->is(tok::equal))
  95       nextToken();
  96     parseTail();
  97     return true;
  98   }
  99
 100   void parseTail() {
 101     while (Current->isNot(tok::eof)) {
 102       Def.Body.push_back(Current);
 103       nextToken();
 104     }
 105     Def.Body.push_back(Current);
 106   }
 107
 108   void nextToken() {
 109     if (Pos + 1 < Tokens.size())
 110       ++Pos;
 111     Current = Tokens[Pos];
 112     Current->Finalized = true;
 113   }
 114
 115   size_t Pos = 0;
 116   FormatToken *Current = nullptr;
 117   Definition Def;
 118   ArrayRef<FormatToken *> Tokens;
 119 };
 120
 121 MacroExpander::MacroExpander(
 122     const std::vector<std::string> &Macros, clang::SourceManager &SourceMgr,
 123     const FormatStyle &Style,
 124     llvm::SpecificBumpPtrAllocator<FormatToken> &Allocator,
 125     IdentifierTable &IdentTable)
 126     : SourceMgr(SourceMgr), Style(Style), Allocator(Allocator),
 127       IdentTable(IdentTable) {
 128   for (const std::string &Macro : Macros)
 129     parseDefinition(Macro);
 130 }
 131
 132 MacroExpander::~MacroExpander() = default;
 133
 134 void MacroExpander::parseDefinition(const std::string &Macro) {
 135   Buffers.push_back(
 136       llvm::MemoryBuffer::getMemBufferCopy(Macro, "<scratch space>"));
 137   clang::FileID FID = SourceMgr.createFileID(Buffers.back()->getMemBufferRef());
 138   FormatTokenLexer Lex(SourceMgr, FID, 0, Style, encoding::Encoding_UTF8,
 139                        Allocator, IdentTable);
 140   const auto Tokens = Lex.lex();
 141   if (!Tokens.empty()) {
 142     DefinitionParser Parser(Tokens);
 143     auto Definition = Parser.parse();
 144     if (Definition.ObjectLike) {
 145       ObjectLike[Definition.Name] = std::move(Definition);
 146     } else {
 147       FunctionLike[Definition.Name][Definition.Params.size()] =
 148           std::move(Definition);
 149     }
 150   }
 151 }
 152
 153 bool MacroExpander::defined(llvm::StringRef Name) const {
 154   return FunctionLike.contains(Name) || ObjectLike.contains(Name);
 155 }
 156
 157 bool MacroExpander::objectLike(llvm::StringRef Name) const {
 158   return ObjectLike.contains(Name);
 159 }
 160
 161 bool MacroExpander::hasArity(llvm::StringRef Name, unsigned Arity) const {
 162   auto it = FunctionLike.find(Name);
 163   return it != FunctionLike.end() && it->second.contains(Arity);
 164 }
 165
 166 llvm::SmallVector<FormatToken *, 8>
 167 MacroExpander::expand(FormatToken *ID,
 168                       std::optional<ArgsList> OptionalArgs) const {
 169   if (OptionalArgs)
 170     assert(hasArity(ID->TokenText, OptionalArgs->size()));
 171   else
 172     assert(objectLike(ID->TokenText));
 173   const Definition &Def = OptionalArgs
 174                               ? FunctionLike.find(ID->TokenText)
 175                                     ->second.find(OptionalArgs.value().size())
 176                                     ->second
 177                               : ObjectLike.find(ID->TokenText)->second;
 178   ArgsList Args = OptionalArgs ? OptionalArgs.value() : ArgsList();
 179   SmallVector<FormatToken *, 8> Result;
 180   // Expand each argument at most once.
 181   llvm::StringSet<> ExpandedArgs;
 182
 183   // Adds the given token to Result.
 184   auto pushToken = [&](FormatToken *Tok) {
 185     Tok->MacroCtx->ExpandedFrom.push_back(ID);
 186     Result.push_back(Tok);
 187   };
 188
 189   // If Tok references a parameter, adds the corresponding argument to Result.
 190   // Returns false if Tok does not reference a parameter.
 191   auto expandArgument = [&](FormatToken *Tok) -> bool {
 192     // If the current token references a parameter, expand the corresponding
 193     // argument.
 194     if (!Tok->is(tok::identifier) || ExpandedArgs.contains(Tok->TokenText))
 195       return false;
 196     ExpandedArgs.insert(Tok->TokenText);
 197     auto I = Def.ArgMap.find(Tok->TokenText);
 198     if (I == Def.ArgMap.end())
 199       return false;
 200     // If there are fewer arguments than referenced parameters, treat the
 201     // parameter as empty.
 202     // FIXME: Potentially fully abort the expansion instead.
 203     if (I->getValue() >= Args.size())
 204       return true;
 205     for (FormatToken *Arg : Args[I->getValue()]) {
 206       // A token can be part of a macro argument at multiple levels.
 207       // For example, with "ID(x) x":
 208       // in ID(ID(x)), 'x' is expanded first as argument to the inner
 209       // ID, then again as argument to the outer ID. We keep the macro
 210       // role the token had from the inner expansion.
 211       if (!Arg->MacroCtx)
 212         Arg->MacroCtx = MacroExpansion(MR_ExpandedArg);
 213       pushToken(Arg);
 214     }
 215     return true;
 216   };
 217
 218   // Expand the definition into Result.
 219   for (FormatToken *Tok : Def.Body) {
 220     if (expandArgument(Tok))
 221       continue;
 222     // Create a copy of the tokens from the macro body, i.e. were not provided
 223     // by user code.
 224     FormatToken *New = new (Allocator.Allocate()) FormatToken;
 225     New->copyFrom(*Tok);
 226     assert(!New->MacroCtx);
 227     // Tokens that are not part of the user code are not formatted.
 228     New->MacroCtx = MacroExpansion(MR_Hidden);
 229     pushToken(New);
 230   }
 231   assert(Result.size() >= 1 && Result.back()->is(tok::eof));
 232   if (Result.size() > 1) {
 233     ++Result[0]->MacroCtx->StartOfExpansion;
 234     ++Result[Result.size() - 2]->MacroCtx->EndOfExpansion;
 235   }
 236   return Result;
 237 }
 238
 239 } // namespace format
 240 } // namespace clang