clang/lib/Format/FormatTokenSource.h

   1 //===--- FormatTokenSource.h - 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 defines the \c FormatTokenSource interface, which provides a token
  11 /// stream as well as the ability to manipulate the token stream.
  12 ///
  13 //===----------------------------------------------------------------------===//
  14
  15 #ifndef LLVM_CLANG_LIB_FORMAT_FORMATTOKENSOURCE_H
  16 #define LLVM_CLANG_LIB_FORMAT_FORMATTOKENSOURCE_H
  17
  18 #include "FormatToken.h"
  19 #include "UnwrappedLineParser.h"
  20 #include "llvm/ADT/DenseMap.h"
  21 #include <cstddef>
  22
  23 #define DEBUG_TYPE "format-token-source"
  24
  25 namespace clang {
  26 namespace format {
  27
  28 // Navigate a token stream.
  29 //
  30 // Enables traversal of a token stream, resetting the position in a token
  31 // stream, as well as inserting new tokens.
  32 class FormatTokenSource {
  33 public:
  34   virtual ~FormatTokenSource() {}
  35
  36   // Returns the next token in the token stream.
  37   virtual FormatToken *getNextToken() = 0;
  38
  39   // Returns the token preceding the token returned by the last call to
  40   // getNextToken() in the token stream, or nullptr if no such token exists.
  41   //
  42   // Must not be called directly at the position directly after insertTokens()
  43   // is called.
  44   virtual FormatToken *getPreviousToken() = 0;
  45
  46   // Returns the token that would be returned by the next call to
  47   // getNextToken().
  48   virtual FormatToken *peekNextToken(bool SkipComment = false) = 0;
  49
  50   // Returns whether we are at the end of the file.
  51   // This can be different from whether getNextToken() returned an eof token
  52   // when the FormatTokenSource is a view on a part of the token stream.
  53   virtual bool isEOF() = 0;
  54
  55   // Gets the current position in the token stream, to be used by setPosition().
  56   //
  57   // Note that the value of the position is not meaningful, and specifically
  58   // should not be used to get relative token positions.
  59   virtual unsigned getPosition() = 0;
  60
  61   // Resets the token stream to the state it was in when getPosition() returned
  62   // Position, and return the token at that position in the stream.
  63   virtual FormatToken *setPosition(unsigned Position) = 0;
  64
  65   // Insert the given tokens before the current position.
  66   // Returns the first token in \c Tokens.
  67   // The next returned token will be the second token in \c Tokens.
  68   // Requires the last token in Tokens to be EOF; once the EOF token is reached,
  69   // the next token will be the last token returned by getNextToken();
  70   //
  71   // For example, given the token sequence 'a1 a2':
  72   // getNextToken() -> a1
  73   // insertTokens('b1 b2') -> b1
  74   // getNextToken() -> b2
  75   // getNextToken() -> a1
  76   // getNextToken() -> a2
  77   virtual FormatToken *insertTokens(ArrayRef<FormatToken *> Tokens) = 0;
  78 };
  79
  80 class IndexedTokenSource : public FormatTokenSource {
  81 public:
  82   IndexedTokenSource(ArrayRef<FormatToken *> Tokens)
  83       : Tokens(Tokens), Position(-1) {}
  84
  85   FormatToken *getNextToken() override {
  86     if (Position >= 0 && isEOF()) {
  87       LLVM_DEBUG({
  88         llvm::dbgs() << "Next ";
  89         dbgToken(Position);
  90       });
  91       return Tokens[Position];
  92     }
  93     Position = successor(Position);
  94     LLVM_DEBUG({
  95       llvm::dbgs() << "Next ";
  96       dbgToken(Position);
  97     });
  98     return Tokens[Position];
  99   }
 100
 101   FormatToken *getPreviousToken() override {
 102     assert(Position <= 0 || !Tokens[Position - 1]->is(tok::eof));
 103     return Position > 0 ? Tokens[Position - 1] : nullptr;
 104   }
 105
 106   FormatToken *peekNextToken(bool SkipComment = false) override {
 107     if (isEOF())
 108       return Tokens[Position];
 109     int Next = successor(Position);
 110     if (SkipComment)
 111       while (Tokens[Next]->is(tok::comment))
 112         Next = successor(Next);
 113     LLVM_DEBUG({
 114       llvm::dbgs() << "Peeking ";
 115       dbgToken(Next);
 116     });
 117     return Tokens[Next];
 118   }
 119
 120   bool isEOF() override {
 121     return Position == -1 ? false : Tokens[Position]->is(tok::eof);
 122   }
 123
 124   unsigned getPosition() override {
 125     LLVM_DEBUG(llvm::dbgs() << "Getting Position: " << Position << "\n");
 126     assert(Position >= 0);
 127     return Position;
 128   }
 129
 130   FormatToken *setPosition(unsigned P) override {
 131     LLVM_DEBUG(llvm::dbgs() << "Setting Position: " << P << "\n");
 132     Position = P;
 133     return Tokens[Position];
 134   }
 135
 136   FormatToken *insertTokens(ArrayRef<FormatToken *> New) override {
 137     assert(Position != -1);
 138     assert((*New.rbegin())->Tok.is(tok::eof));
 139     int Next = Tokens.size();
 140     Tokens.append(New.begin(), New.end());
 141     LLVM_DEBUG({
 142       llvm::dbgs() << "Inserting:\n";
 143       for (int I = Next, E = Tokens.size(); I != E; ++I)
 144         dbgToken(I, "  ");
 145       llvm::dbgs() << "  Jump from: " << (Tokens.size() - 1) << " -> "
 146                    << Position << "\n";
 147     });
 148     Jumps[Tokens.size() - 1] = Position;
 149     Position = Next;
 150     LLVM_DEBUG({
 151       llvm::dbgs() << "At inserted token ";
 152       dbgToken(Position);
 153     });
 154     return Tokens[Position];
 155   }
 156
 157   void reset() { Position = -1; }
 158
 159 private:
 160   int successor(int Current) const {
 161     int Next = Current + 1;
 162     auto it = Jumps.find(Next);
 163     if (it != Jumps.end()) {
 164       Next = it->second;
 165       assert(!Jumps.contains(Next));
 166     }
 167     return Next;
 168   }
 169
 170   void dbgToken(int Position, llvm::StringRef Indent = "") {
 171     FormatToken *Tok = Tokens[Position];
 172     llvm::dbgs() << Indent << "[" << Position
 173                  << "] Token: " << Tok->Tok.getName() << " / " << Tok->TokenText
 174                  << ", Macro: " << !!Tok->MacroCtx << "\n";
 175   }
 176
 177   SmallVector<FormatToken *> Tokens;
 178   int Position;
 179
 180   // Maps from position a to position b, so that when we reach a, the token
 181   // stream continues at position b instead.
 182   llvm::DenseMap<int, int> Jumps;
 183 };
 184
 185 class ScopedMacroState : public FormatTokenSource {
 186 public:
 187   ScopedMacroState(UnwrappedLine &Line, FormatTokenSource *&TokenSource,
 188                    FormatToken *&ResetToken)
 189       : Line(Line), TokenSource(TokenSource), ResetToken(ResetToken),
 190         PreviousLineLevel(Line.Level), PreviousTokenSource(TokenSource),
 191         Token(nullptr), PreviousToken(nullptr) {
 192     FakeEOF.Tok.startToken();
 193     FakeEOF.Tok.setKind(tok::eof);
 194     TokenSource = this;
 195     Line.Level = 0;
 196     Line.InPPDirective = true;
 197     // InMacroBody gets set after the `#define x` part.
 198   }
 199
 200   ~ScopedMacroState() override {
 201     TokenSource = PreviousTokenSource;
 202     ResetToken = Token;
 203     Line.InPPDirective = false;
 204     Line.InMacroBody = false;
 205     Line.Level = PreviousLineLevel;
 206   }
 207
 208   FormatToken *getNextToken() override {
 209     // The \c UnwrappedLineParser guards against this by never calling
 210     // \c getNextToken() after it has encountered the first eof token.
 211     assert(!eof());
 212     PreviousToken = Token;
 213     Token = PreviousTokenSource->getNextToken();
 214     if (eof())
 215       return &FakeEOF;
 216     return Token;
 217   }
 218
 219   FormatToken *getPreviousToken() override {
 220     return PreviousTokenSource->getPreviousToken();
 221   }
 222
 223   FormatToken *peekNextToken(bool SkipComment) override {
 224     if (eof())
 225       return &FakeEOF;
 226     return PreviousTokenSource->peekNextToken(SkipComment);
 227   }
 228
 229   bool isEOF() override { return PreviousTokenSource->isEOF(); }
 230
 231   unsigned getPosition() override { return PreviousTokenSource->getPosition(); }
 232
 233   FormatToken *setPosition(unsigned Position) override {
 234     PreviousToken = nullptr;
 235     Token = PreviousTokenSource->setPosition(Position);
 236     return Token;
 237   }
 238
 239   FormatToken *insertTokens(ArrayRef<FormatToken *> Tokens) override {
 240     llvm_unreachable("Cannot insert tokens while parsing a macro.");
 241     return nullptr;
 242   }
 243
 244 private:
 245   bool eof() {
 246     return Token && Token->HasUnescapedNewline &&
 247            !continuesLineComment(*Token, PreviousToken,
 248                                  /*MinColumnToken=*/PreviousToken);
 249   }
 250
 251   FormatToken FakeEOF;
 252   UnwrappedLine &Line;
 253   FormatTokenSource *&TokenSource;
 254   FormatToken *&ResetToken;
 255   unsigned PreviousLineLevel;
 256   FormatTokenSource *PreviousTokenSource;
 257
 258   FormatToken *Token;
 259   FormatToken *PreviousToken;
 260 };
 261
 262 } // namespace format
 263 } // namespace clang
 264
 265 #undef DEBUG_TYPE
 266
 267 #endif