1 //===--- PPCaching.cpp - Handle caching lexed tokens ----------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements pieces of the Preprocessor interface that manage the
11 // caching of lexed tokens.
13 //===----------------------------------------------------------------------===//
15 #include "clang/Lex/Preprocessor.h"
16 using namespace clang;
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.
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.
26 void Preprocessor::EnableBacktrackAtThisPos() {
27 BacktrackPositions.push_back(CachedLexPos);
28 EnterCachingLexMode();
31 /// CommitBacktrackedTokens - Disable the last EnableBacktrackAtThisPos call.
32 void Preprocessor::CommitBacktrackedTokens() {
33 assert(!BacktrackPositions.empty()
34 && "EnableBacktrackAtThisPos was not called!");
35 BacktrackPositions.pop_back();
38 /// Backtrack - Make Preprocessor re-lex the tokens that were lexed since
39 /// EnableBacktrackAtThisPos() was previously called.
40 void Preprocessor::Backtrack() {
41 assert(!BacktrackPositions.empty()
42 && "EnableBacktrackAtThisPos was not called!");
43 CachedLexPos = BacktrackPositions.back();
44 BacktrackPositions.pop_back();
47 void Preprocessor::CachingLex(Token &Result) {
48 if (!InCachingLexMode())
51 if (CachedLexPos < CachedTokens.size()) {
52 Result = CachedTokens[CachedLexPos++];
59 if (!isBacktrackEnabled()) {
60 // All cached tokens were consumed.
66 // Cache the lexed token.
67 EnterCachingLexMode();
68 CachedTokens.push_back(Result);
72 void Preprocessor::EnterCachingLexMode() {
73 if (InCachingLexMode())
76 PushIncludeMacroStack();
77 if (CurLexerKind != CLK_LexAfterModuleImport)
78 CurLexerKind = CLK_CachingLexer;
82 const Token &Preprocessor::PeekAhead(unsigned N) {
83 assert(CachedLexPos + N > CachedTokens.size() && "Confused caching.");
85 for (unsigned C = CachedLexPos + N - CachedTokens.size(); C > 0; --C) {
86 CachedTokens.push_back(Token());
87 Lex(CachedTokens.back());
89 EnterCachingLexMode();
90 return CachedTokens.back();
93 void Preprocessor::AnnotatePreviousCachedTokens(const Token &Tok) {
94 assert(Tok.isAnnotation() && "Expected annotation token");
95 assert(CachedLexPos != 0 && "Expected to have some cached tokens");
96 assert(CachedTokens[CachedLexPos-1].getLastLoc() == Tok.getAnnotationEndLoc()
97 && "The annotation should be until the most recent cached token");
99 // Start from the end of the cached tokens list and look for the token
100 // that is the beginning of the annotation token.
101 for (CachedTokensTy::size_type i = CachedLexPos; i != 0; --i) {
102 CachedTokensTy::iterator AnnotBegin = CachedTokens.begin() + i-1;
103 if (AnnotBegin->getLocation() == Tok.getLocation()) {
104 assert((BacktrackPositions.empty() || BacktrackPositions.back() < i) &&
105 "The backtrack pos points inside the annotated tokens!");
106 // Replace the cached tokens with the single annotation token.
107 if (i < CachedLexPos)
108 CachedTokens.erase(AnnotBegin + 1, CachedTokens.begin() + CachedLexPos);