119 lines
3.9 KiB
C++
119 lines
3.9 KiB
C++
//===--- PPCaching.cpp - Handle caching lexed tokens ----------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements pieces of the Preprocessor interface that manage the
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// caching of lexed tokens.
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//
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//===----------------------------------------------------------------------===//
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#include "clang/Lex/Preprocessor.h"
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using namespace clang;
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// EnableBacktrackAtThisPos - From the point that this method is called, and
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// until CommitBacktrackedTokens() or Backtrack() is called, the Preprocessor
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// keeps track of the lexed tokens so that a subsequent Backtrack() call will
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// make the Preprocessor re-lex the same tokens.
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//
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// Nested backtracks are allowed, meaning that EnableBacktrackAtThisPos can
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// be called multiple times and CommitBacktrackedTokens/Backtrack calls will
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// be combined with the EnableBacktrackAtThisPos calls in reverse order.
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void Preprocessor::EnableBacktrackAtThisPos() {
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BacktrackPositions.push_back(CachedLexPos);
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EnterCachingLexMode();
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}
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// Disable the last EnableBacktrackAtThisPos call.
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void Preprocessor::CommitBacktrackedTokens() {
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assert(!BacktrackPositions.empty()
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&& "EnableBacktrackAtThisPos was not called!");
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BacktrackPositions.pop_back();
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}
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// Make Preprocessor re-lex the tokens that were lexed since
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// EnableBacktrackAtThisPos() was previously called.
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void Preprocessor::Backtrack() {
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assert(!BacktrackPositions.empty()
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&& "EnableBacktrackAtThisPos was not called!");
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CachedLexPos = BacktrackPositions.back();
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BacktrackPositions.pop_back();
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recomputeCurLexerKind();
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}
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void Preprocessor::CachingLex(Token &Result) {
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if (!InCachingLexMode())
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return;
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if (CachedLexPos < CachedTokens.size()) {
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Result = CachedTokens[CachedLexPos++];
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return;
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}
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ExitCachingLexMode();
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Lex(Result);
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if (isBacktrackEnabled()) {
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// Cache the lexed token.
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EnterCachingLexMode();
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CachedTokens.push_back(Result);
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++CachedLexPos;
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return;
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}
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if (CachedLexPos < CachedTokens.size()) {
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EnterCachingLexMode();
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} else {
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// All cached tokens were consumed.
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CachedTokens.clear();
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CachedLexPos = 0;
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}
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}
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void Preprocessor::EnterCachingLexMode() {
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if (InCachingLexMode())
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return;
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PushIncludeMacroStack();
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CurLexerKind = CLK_CachingLexer;
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}
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const Token &Preprocessor::PeekAhead(unsigned N) {
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assert(CachedLexPos + N > CachedTokens.size() && "Confused caching.");
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ExitCachingLexMode();
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for (unsigned C = CachedLexPos + N - CachedTokens.size(); C > 0; --C) {
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CachedTokens.push_back(Token());
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Lex(CachedTokens.back());
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}
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EnterCachingLexMode();
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return CachedTokens.back();
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}
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void Preprocessor::AnnotatePreviousCachedTokens(const Token &Tok) {
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assert(Tok.isAnnotation() && "Expected annotation token");
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assert(CachedLexPos != 0 && "Expected to have some cached tokens");
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assert(CachedTokens[CachedLexPos-1].getLastLoc() == Tok.getAnnotationEndLoc()
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&& "The annotation should be until the most recent cached token");
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// Start from the end of the cached tokens list and look for the token
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// that is the beginning of the annotation token.
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for (CachedTokensTy::size_type i = CachedLexPos; i != 0; --i) {
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CachedTokensTy::iterator AnnotBegin = CachedTokens.begin() + i-1;
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if (AnnotBegin->getLocation() == Tok.getLocation()) {
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assert((BacktrackPositions.empty() || BacktrackPositions.back() < i) &&
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"The backtrack pos points inside the annotated tokens!");
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// Replace the cached tokens with the single annotation token.
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if (i < CachedLexPos)
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CachedTokens.erase(AnnotBegin + 1, CachedTokens.begin() + CachedLexPos);
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*AnnotBegin = Tok;
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CachedLexPos = i;
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return;
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}
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}
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}
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