clang  3.9.0
PPCaching.cpp
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1 //===--- PPCaching.cpp - Handle caching lexed tokens ----------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements pieces of the Preprocessor interface that manage the
11 // caching of lexed tokens.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "clang/Lex/Preprocessor.h"
16 using namespace clang;
17 
18 // EnableBacktrackAtThisPos - From the point that this method is called, and
19 // until CommitBacktrackedTokens() or Backtrack() is called, the Preprocessor
20 // keeps track of the lexed tokens so that a subsequent Backtrack() call will
21 // make the Preprocessor re-lex the same tokens.
22 //
23 // Nested backtracks are allowed, meaning that EnableBacktrackAtThisPos can
24 // be called multiple times and CommitBacktrackedTokens/Backtrack calls will
25 // be combined with the EnableBacktrackAtThisPos calls in reverse order.
27  BacktrackPositions.push_back(CachedLexPos);
28  EnterCachingLexMode();
29 }
30 
31 // Disable the last EnableBacktrackAtThisPos call.
33  assert(!BacktrackPositions.empty()
34  && "EnableBacktrackAtThisPos was not called!");
35  BacktrackPositions.pop_back();
36 }
37 
38 // Make Preprocessor re-lex the tokens that were lexed since
39 // EnableBacktrackAtThisPos() was previously called.
41  assert(!BacktrackPositions.empty()
42  && "EnableBacktrackAtThisPos was not called!");
43  CachedLexPos = BacktrackPositions.back();
44  BacktrackPositions.pop_back();
46 }
47 
48 void Preprocessor::CachingLex(Token &Result) {
49  if (!InCachingLexMode())
50  return;
51 
52  if (CachedLexPos < CachedTokens.size()) {
53  Result = CachedTokens[CachedLexPos++];
54  return;
55  }
56 
57  ExitCachingLexMode();
58  Lex(Result);
59 
60  if (isBacktrackEnabled()) {
61  // Cache the lexed token.
62  EnterCachingLexMode();
63  CachedTokens.push_back(Result);
64  ++CachedLexPos;
65  return;
66  }
67 
68  if (CachedLexPos < CachedTokens.size()) {
69  EnterCachingLexMode();
70  } else {
71  // All cached tokens were consumed.
72  CachedTokens.clear();
73  CachedLexPos = 0;
74  }
75 }
76 
77 void Preprocessor::EnterCachingLexMode() {
78  if (InCachingLexMode())
79  return;
80 
81  PushIncludeMacroStack();
82  CurLexerKind = CLK_CachingLexer;
83 }
84 
85 
86 const Token &Preprocessor::PeekAhead(unsigned N) {
87  assert(CachedLexPos + N > CachedTokens.size() && "Confused caching.");
88  ExitCachingLexMode();
89  for (unsigned C = CachedLexPos + N - CachedTokens.size(); C > 0; --C) {
90  CachedTokens.push_back(Token());
91  Lex(CachedTokens.back());
92  }
93  EnterCachingLexMode();
94  return CachedTokens.back();
95 }
96 
97 void Preprocessor::AnnotatePreviousCachedTokens(const Token &Tok) {
98  assert(Tok.isAnnotation() && "Expected annotation token");
99  assert(CachedLexPos != 0 && "Expected to have some cached tokens");
100  assert(CachedTokens[CachedLexPos-1].getLastLoc() == Tok.getAnnotationEndLoc()
101  && "The annotation should be until the most recent cached token");
102 
103  // Start from the end of the cached tokens list and look for the token
104  // that is the beginning of the annotation token.
105  for (CachedTokensTy::size_type i = CachedLexPos; i != 0; --i) {
106  CachedTokensTy::iterator AnnotBegin = CachedTokens.begin() + i-1;
107  if (AnnotBegin->getLocation() == Tok.getLocation()) {
108  assert((BacktrackPositions.empty() || BacktrackPositions.back() < i) &&
109  "The backtrack pos points inside the annotated tokens!");
110  // Replace the cached tokens with the single annotation token.
111  if (i < CachedLexPos)
112  CachedTokens.erase(AnnotBegin + 1, CachedTokens.begin() + CachedLexPos);
113  *AnnotBegin = Tok;
114  CachedLexPos = i;
115  return;
116  }
117  }
118 }
119 
121  // There's currently no cached token...
122  if (!CachedLexPos)
123  return false;
124 
125  const Token LastCachedTok = CachedTokens[CachedLexPos - 1];
126  if (LastCachedTok.getKind() != Tok.getKind())
127  return false;
128 
129  int RelOffset = 0;
130  if ((!getSourceManager().isInSameSLocAddrSpace(
131  Tok.getLocation(), getLastCachedTokenLocation(), &RelOffset)) ||
132  RelOffset)
133  return false;
134 
135  return true;
136 }
137 
139  assert(CachedLexPos != 0 && "Expected to have some cached tokens");
140  CachedTokens.insert(CachedTokens.begin() + CachedLexPos - 1, NewToks.begin(),
141  NewToks.end());
142  CachedTokens.erase(CachedTokens.begin() + CachedLexPos - 1 + NewToks.size());
143  CachedLexPos += NewToks.size() - 1;
144 }
SourceManager & getSourceManager() const
Definition: Preprocessor.h:694
void ReplacePreviousCachedToken(ArrayRef< Token > NewToks)
Replace token in CachedLexPos - 1 in CachedTokens by the tokens in NewToks.
Definition: PPCaching.cpp:138
SourceLocation getLastCachedTokenLocation() const
Get the location of the last cached token, suitable for setting the end location of an annotation tok...
Token - This structure provides full information about a lexed token.
Definition: Token.h:35
void CommitBacktrackedTokens()
Disable the last EnableBacktrackAtThisPos call.
Definition: PPCaching.cpp:32
tok::TokenKind getKind() const
Definition: Token.h:89
void recomputeCurLexerKind()
Recompute the current lexer kind based on the CurLexer/CurPTHLexer/ CurTokenLexer pointers...
void Backtrack()
Make Preprocessor re-lex the tokens that were lexed since EnableBacktrackAtThisPos() was previously c...
Definition: PPCaching.cpp:40
void EnableBacktrackAtThisPos()
From the point that this method is called, and until CommitBacktrackedTokens() or Backtrack() is call...
Definition: PPCaching.cpp:26
Defines the clang::Preprocessor interface.
FormatToken * Token
SourceLocation getLocation() const
Return a source location identifier for the specified offset in the current file. ...
Definition: Token.h:123
SourceLocation getAnnotationEndLoc() const
Definition: Token.h:137
const TemplateArgument * iterator
Definition: Type.h:4233
void Lex(Token &Result)
Lex the next token for this preprocessor.
bool IsPreviousCachedToken(const Token &Tok) const
Whether Tok is the most recent token (CachedLexPos - 1) in CachedTokens.
Definition: PPCaching.cpp:120
bool isAnnotation() const
Return true if this is any of tok::annot_* kind tokens.
Definition: Token.h:117
bool isBacktrackEnabled() const
True if EnableBacktrackAtThisPos() was called and caching of tokens is on.