//===--- TokenLexer.cpp - Lex from a token stream -------------------------===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This file implements the TokenLexer interface. // //===----------------------------------------------------------------------===// #include "clang/Lex/TokenLexer.h" #include "MacroArgs.h" #include "clang/Lex/MacroInfo.h" #include "clang/Lex/Preprocessor.h" #include "clang/Basic/SourceManager.h" #include "clang/Basic/Diagnostic.h" #include "llvm/ADT/SmallVector.h" using namespace clang; /// Create a TokenLexer for the specified macro with the specified actual /// arguments. Note that this ctor takes ownership of the ActualArgs pointer. void TokenLexer::Init(Token &Tok, MacroArgs *Actuals) { // If the client is reusing a TokenLexer, make sure to free any memory // associated with it. destroy(); Macro = PP.getMacroInfo(Tok.getIdentifierInfo()); ActualArgs = Actuals; CurToken = 0; InstantiateLoc = Tok.getLocation(); AtStartOfLine = Tok.isAtStartOfLine(); HasLeadingSpace = Tok.hasLeadingSpace(); Tokens = &*Macro->tokens_begin(); OwnsTokens = false; DisableMacroExpansion = false; NumTokens = Macro->tokens_end()-Macro->tokens_begin(); // If this is a function-like macro, expand the arguments and change // Tokens to point to the expanded tokens. if (Macro->isFunctionLike() && Macro->getNumArgs()) ExpandFunctionArguments(); // Mark the macro as currently disabled, so that it is not recursively // expanded. The macro must be disabled only after argument pre-expansion of // function-like macro arguments occurs. Macro->DisableMacro(); } /// Create a TokenLexer for the specified token stream. This does not /// take ownership of the specified token vector. void TokenLexer::Init(const Token *TokArray, unsigned NumToks, bool disableMacroExpansion, bool ownsTokens) { // If the client is reusing a TokenLexer, make sure to free any memory // associated with it. destroy(); Macro = 0; ActualArgs = 0; Tokens = TokArray; OwnsTokens = ownsTokens; DisableMacroExpansion = disableMacroExpansion; NumTokens = NumToks; CurToken = 0; InstantiateLoc = SourceLocation(); AtStartOfLine = false; HasLeadingSpace = false; // Set HasLeadingSpace/AtStartOfLine so that the first token will be // returned unmodified. if (NumToks != 0) { AtStartOfLine = TokArray[0].isAtStartOfLine(); HasLeadingSpace = TokArray[0].hasLeadingSpace(); } } void TokenLexer::destroy() { // If this was a function-like macro that actually uses its arguments, delete // the expanded tokens. if (OwnsTokens) { delete [] Tokens; Tokens = 0; } // TokenLexer owns its formal arguments. if (ActualArgs) ActualArgs->destroy(); } /// Expand the arguments of a function-like macro so that we can quickly /// return preexpanded tokens from Tokens. void TokenLexer::ExpandFunctionArguments() { llvm::SmallVector ResultToks; // Loop through 'Tokens', expanding them into ResultToks. Keep // track of whether we change anything. If not, no need to keep them. If so, // we install the newly expanded sequence as the new 'Tokens' list. bool MadeChange = false; // NextTokGetsSpace - When this is true, the next token appended to the // output list will get a leading space, regardless of whether it had one to // begin with or not. This is used for placemarker support. bool NextTokGetsSpace = false; for (unsigned i = 0, e = NumTokens; i != e; ++i) { // If we found the stringify operator, get the argument stringified. The // preprocessor already verified that the following token is a macro name // when the #define was parsed. const Token &CurTok = Tokens[i]; if (CurTok.is(tok::hash) || CurTok.is(tok::hashat)) { int ArgNo = Macro->getArgumentNum(Tokens[i+1].getIdentifierInfo()); assert(ArgNo != -1 && "Token following # is not an argument?"); Token Res; if (CurTok.is(tok::hash)) // Stringify Res = ActualArgs->getStringifiedArgument(ArgNo, PP); else { // 'charify': don't bother caching these. Res = MacroArgs::StringifyArgument(ActualArgs->getUnexpArgument(ArgNo), PP, true); } // The stringified/charified string leading space flag gets set to match // the #/#@ operator. if (CurTok.hasLeadingSpace() || NextTokGetsSpace) Res.setFlag(Token::LeadingSpace); ResultToks.push_back(Res); MadeChange = true; ++i; // Skip arg name. NextTokGetsSpace = false; continue; } // Otherwise, if this is not an argument token, just add the token to the // output buffer. IdentifierInfo *II = CurTok.getIdentifierInfo(); int ArgNo = II ? Macro->getArgumentNum(II) : -1; if (ArgNo == -1) { // This isn't an argument, just add it. ResultToks.push_back(CurTok); if (NextTokGetsSpace) { ResultToks.back().setFlag(Token::LeadingSpace); NextTokGetsSpace = false; } continue; } // An argument is expanded somehow, the result is different than the // input. MadeChange = true; // Otherwise, this is a use of the argument. Find out if there is a paste // (##) operator before or after the argument. bool PasteBefore = !ResultToks.empty() && ResultToks.back().is(tok::hashhash); bool PasteAfter = i+1 != e && Tokens[i+1].is(tok::hashhash); // If it is not the LHS/RHS of a ## operator, we must pre-expand the // argument and substitute the expanded tokens into the result. This is // C99 6.10.3.1p1. if (!PasteBefore && !PasteAfter) { const Token *ResultArgToks; // Only preexpand the argument if it could possibly need it. This // avoids some work in common cases. const Token *ArgTok = ActualArgs->getUnexpArgument(ArgNo); if (ActualArgs->ArgNeedsPreexpansion(ArgTok, PP)) ResultArgToks = &ActualArgs->getPreExpArgument(ArgNo, PP)[0]; else ResultArgToks = ArgTok; // Use non-preexpanded tokens. // If the arg token expanded into anything, append it. if (ResultArgToks->isNot(tok::eof)) { unsigned FirstResult = ResultToks.size(); unsigned NumToks = MacroArgs::getArgLength(ResultArgToks); ResultToks.append(ResultArgToks, ResultArgToks+NumToks); // If any tokens were substituted from the argument, the whitespace // before the first token should match the whitespace of the arg // identifier. ResultToks[FirstResult].setFlagValue(Token::LeadingSpace, CurTok.hasLeadingSpace() || NextTokGetsSpace); NextTokGetsSpace = false; } else { // If this is an empty argument, and if there was whitespace before the // formal token, make sure the next token gets whitespace before it. NextTokGetsSpace = CurTok.hasLeadingSpace(); } continue; } // Okay, we have a token that is either the LHS or RHS of a paste (##) // argument. It gets substituted as its non-pre-expanded tokens. const Token *ArgToks = ActualArgs->getUnexpArgument(ArgNo); unsigned NumToks = MacroArgs::getArgLength(ArgToks); if (NumToks) { // Not an empty argument? // If this is the GNU ", ## __VA_ARG__" extension, and we just learned // that __VA_ARG__ expands to multiple tokens, avoid a pasting error when // the expander trys to paste ',' with the first token of the __VA_ARG__ // expansion. if (PasteBefore && ResultToks.size() >= 2 && ResultToks[ResultToks.size()-2].is(tok::comma) && (unsigned)ArgNo == Macro->getNumArgs()-1 && Macro->isVariadic()) { // Remove the paste operator, report use of the extension. PP.Diag(ResultToks.back().getLocation(), diag::ext_paste_comma); ResultToks.pop_back(); } ResultToks.append(ArgToks, ArgToks+NumToks); // If the next token was supposed to get leading whitespace, ensure it has // it now. if (NextTokGetsSpace) { ResultToks[ResultToks.size()-NumToks].setFlag(Token::LeadingSpace); NextTokGetsSpace = false; } continue; } // If an empty argument is on the LHS or RHS of a paste, the standard (C99 // 6.10.3.3p2,3) calls for a bunch of placemarker stuff to occur. We // implement this by eating ## operators when a LHS or RHS expands to // empty. NextTokGetsSpace |= CurTok.hasLeadingSpace(); if (PasteAfter) { // Discard the argument token and skip (don't copy to the expansion // buffer) the paste operator after it. NextTokGetsSpace |= Tokens[i+1].hasLeadingSpace(); ++i; continue; } // If this is on the RHS of a paste operator, we've already copied the // paste operator to the ResultToks list. Remove it. assert(PasteBefore && ResultToks.back().is(tok::hashhash)); NextTokGetsSpace |= ResultToks.back().hasLeadingSpace(); ResultToks.pop_back(); // If this is the __VA_ARGS__ token, and if the argument wasn't provided, // and if the macro had at least one real argument, and if the token before // the ## was a comma, remove the comma. if ((unsigned)ArgNo == Macro->getNumArgs()-1 && // is __VA_ARGS__ ActualArgs->isVarargsElidedUse() && // Argument elided. !ResultToks.empty() && ResultToks.back().is(tok::comma)) { // Never add a space, even if the comma, ##, or arg had a space. NextTokGetsSpace = false; // Remove the paste operator, report use of the extension. PP.Diag(ResultToks.back().getLocation(), diag::ext_paste_comma); ResultToks.pop_back(); } continue; } // If anything changed, install this as the new Tokens list. if (MadeChange) { // This is deleted in the dtor. NumTokens = ResultToks.size(); Token *Res = new Token[ResultToks.size()]; if (NumTokens) memcpy(Res, &ResultToks[0], NumTokens*sizeof(Token)); Tokens = Res; OwnsTokens = true; } } /// Lex - Lex and return a token from this macro stream. /// void TokenLexer::Lex(Token &Tok) { // Lexing off the end of the macro, pop this macro off the expansion stack. if (isAtEnd()) { // If this is a macro (not a token stream), mark the macro enabled now // that it is no longer being expanded. if (Macro) Macro->EnableMacro(); // Pop this context off the preprocessors lexer stack and get the next // token. This will delete "this" so remember the PP instance var. Preprocessor &PPCache = PP; if (PP.HandleEndOfTokenLexer(Tok)) return; // HandleEndOfTokenLexer may not return a token. If it doesn't, lex // whatever is next. return PPCache.Lex(Tok); } // If this is the first token of the expanded result, we inherit spacing // properties later. bool isFirstToken = CurToken == 0; // Get the next token to return. Tok = Tokens[CurToken++]; // If this token is followed by a token paste (##) operator, paste the tokens! if (!isAtEnd() && Tokens[CurToken].is(tok::hashhash)) if (PasteTokens(Tok)) { // When handling the microsoft /##/ extension, the final token is // returned by PasteTokens, not the pasted token. return; } // The token's current location indicate where the token was lexed from. We // need this information to compute the spelling of the token, but any // diagnostics for the expanded token should appear as if they came from // InstantiationLoc. Pull this information together into a new SourceLocation // that captures all of this. if (InstantiateLoc.isValid()) { // Don't do this for token streams. SourceManager &SrcMgr = PP.getSourceManager(); Tok.setLocation(SrcMgr.getInstantiationLoc(Tok.getLocation(), InstantiateLoc)); } // If this is the first token, set the lexical properties of the token to // match the lexical properties of the macro identifier. if (isFirstToken) { Tok.setFlagValue(Token::StartOfLine , AtStartOfLine); Tok.setFlagValue(Token::LeadingSpace, HasLeadingSpace); } // Handle recursive expansion! if (Tok.getIdentifierInfo() && !DisableMacroExpansion) return PP.HandleIdentifier(Tok); // Otherwise, return a normal token. } /// PasteTokens - Tok is the LHS of a ## operator, and CurToken is the ## /// operator. Read the ## and RHS, and paste the LHS/RHS together. If there /// are more ## after it, chomp them iteratively. Return the result as Tok. /// If this returns true, the caller should immediately return the token. bool TokenLexer::PasteTokens(Token &Tok) { llvm::SmallVector Buffer; do { // Consume the ## operator. SourceLocation PasteOpLoc = Tokens[CurToken].getLocation(); ++CurToken; assert(!isAtEnd() && "No token on the RHS of a paste operator!"); // Get the RHS token. const Token &RHS = Tokens[CurToken]; bool isInvalid = false; // Allocate space for the result token. This is guaranteed to be enough for // the two tokens and a null terminator. Buffer.resize(Tok.getLength() + RHS.getLength() + 1); // Get the spelling of the LHS token in Buffer. const char *BufPtr = &Buffer[0]; unsigned LHSLen = PP.getSpelling(Tok, BufPtr); if (BufPtr != &Buffer[0]) // Really, we want the chars in Buffer! memcpy(&Buffer[0], BufPtr, LHSLen); BufPtr = &Buffer[LHSLen]; unsigned RHSLen = PP.getSpelling(RHS, BufPtr); if (BufPtr != &Buffer[LHSLen]) // Really, we want the chars in Buffer! memcpy(&Buffer[LHSLen], BufPtr, RHSLen); // Add null terminator. Buffer[LHSLen+RHSLen] = '\0'; // Trim excess space. Buffer.resize(LHSLen+RHSLen+1); // Plop the pasted result (including the trailing newline and null) into a // scratch buffer where we can lex it. SourceLocation ResultTokLoc = PP.CreateString(&Buffer[0], Buffer.size()); // Lex the resultant pasted token into Result. Token Result; if (Tok.is(tok::identifier) && RHS.is(tok::identifier)) { // Common paste case: identifier+identifier = identifier. Avoid creating // a lexer and other overhead. PP.IncrementPasteCounter(true); Result.startToken(); Result.setKind(tok::identifier); Result.setLocation(ResultTokLoc); Result.setLength(LHSLen+RHSLen); } else { PP.IncrementPasteCounter(false); // Make a lexer to lex this string from. SourceManager &SourceMgr = PP.getSourceManager(); const char *ResultStrData = SourceMgr.getCharacterData(ResultTokLoc); const llvm::MemoryBuffer *Buffer = SourceMgr.getBuffer(ResultTokLoc.getFileID()); // Make a lexer object so that we lex and expand the paste result. Lexer TL(ResultTokLoc, PP.getLangOptions(), ResultStrData, ResultStrData+LHSLen+RHSLen /*don't include null*/, Buffer); // Lex a token in raw mode. This way it won't look up identifiers // automatically, lexing off the end will return an eof token, and // warnings are disabled. This returns true if the result token is the // entire buffer. bool IsComplete = TL.LexFromRawLexer(Result); // If we got an EOF token, we didn't form even ONE token. For example, we // did "/ ## /" to get "//". IsComplete &= Result.isNot(tok::eof); isInvalid = !IsComplete; } // If pasting the two tokens didn't form a full new token, this is an error. // This occurs with "x ## +" and other stuff. Return with Tok unmodified // and with RHS as the next token to lex. if (isInvalid) { // Test for the Microsoft extension of /##/ turning into // here on the // error path. if (PP.getLangOptions().Microsoft && Tok.is(tok::slash) && RHS.is(tok::slash)) { HandleMicrosoftCommentPaste(Tok); return true; } else { // TODO: If not in assembler language mode. PP.Diag(PasteOpLoc, diag::err_pp_bad_paste) << std::string(Buffer.begin(), Buffer.end()-1); return false; } } // Turn ## into 'unknown' to avoid # ## # from looking like a paste // operator. if (Result.is(tok::hashhash)) Result.setKind(tok::unknown); // FIXME: Turn __VA_ARGS__ into "not a token"? // Transfer properties of the LHS over the the Result. Result.setFlagValue(Token::StartOfLine , Tok.isAtStartOfLine()); Result.setFlagValue(Token::LeadingSpace, Tok.hasLeadingSpace()); // Finally, replace LHS with the result, consume the RHS, and iterate. ++CurToken; Tok = Result; } while (!isAtEnd() && Tokens[CurToken].is(tok::hashhash)); // Now that we got the result token, it will be subject to expansion. Since // token pasting re-lexes the result token in raw mode, identifier information // isn't looked up. As such, if the result is an identifier, look up id info. if (Tok.is(tok::identifier)) { // Look up the identifier info for the token. We disabled identifier lookup // by saying we're skipping contents, so we need to do this manually. Tok.setIdentifierInfo(PP.LookUpIdentifierInfo(Tok)); } return false; } /// isNextTokenLParen - If the next token lexed will pop this macro off the /// expansion stack, return 2. If the next unexpanded token is a '(', return /// 1, otherwise return 0. unsigned TokenLexer::isNextTokenLParen() const { // Out of tokens? if (isAtEnd()) return 2; return Tokens[CurToken].is(tok::l_paren); } /// HandleMicrosoftCommentPaste - In microsoft compatibility mode, /##/ pastes /// together to form a comment that comments out everything in the current /// macro, other active macros, and anything left on the current physical /// source line of the instantiated buffer. Handle this by returning the /// first token on the next line. void TokenLexer::HandleMicrosoftCommentPaste(Token &Tok) { // We 'comment out' the rest of this macro by just ignoring the rest of the // tokens that have not been lexed yet, if any. // Since this must be a macro, mark the macro enabled now that it is no longer // being expanded. assert(Macro && "Token streams can't paste comments"); Macro->EnableMacro(); PP.HandleMicrosoftCommentPaste(Tok); }