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//===--- TokenConcatenation.cpp - Token Concatenation Avoidance -----------===//
//
// 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 TokenConcatenation class.
//
//===----------------------------------------------------------------------===//
#include "clang/Lex/TokenConcatenation.h"
#include "clang/Lex/Preprocessor.h"
using namespace clang;
/// StartsWithL - Return true if the spelling of this token starts with 'L'.
bool TokenConcatenation::StartsWithL(const Token &Tok) const {
if (!Tok.needsCleaning()) {
SourceManager &SM = PP.getSourceManager();
return *SM.getCharacterData(SM.getSpellingLoc(Tok.getLocation())) == 'L';
}
if (Tok.getLength() < 256) {
char Buffer[256];
const char *TokPtr = Buffer;
PP.getSpelling(Tok, TokPtr);
return TokPtr[0] == 'L';
}
return PP.getSpelling(Tok)[0] == 'L';
}
/// IsIdentifierL - Return true if the spelling of this token is literally
/// 'L'.
bool TokenConcatenation::IsIdentifierL(const Token &Tok) const {
if (!Tok.needsCleaning()) {
if (Tok.getLength() != 1)
return false;
SourceManager &SM = PP.getSourceManager();
return *SM.getCharacterData(SM.getSpellingLoc(Tok.getLocation())) == 'L';
}
if (Tok.getLength() < 256) {
char Buffer[256];
const char *TokPtr = Buffer;
if (PP.getSpelling(Tok, TokPtr) != 1)
return false;
return TokPtr[0] == 'L';
}
return PP.getSpelling(Tok) == "L";
}
TokenConcatenation::TokenConcatenation(Preprocessor &pp) : PP(pp) {
memset(TokenInfo, 0, sizeof(TokenInfo));
// These tokens have custom code in AvoidConcat.
TokenInfo[tok::identifier ] |= aci_custom;
TokenInfo[tok::numeric_constant] |= aci_custom_firstchar;
TokenInfo[tok::period ] |= aci_custom_firstchar;
TokenInfo[tok::amp ] |= aci_custom_firstchar;
TokenInfo[tok::plus ] |= aci_custom_firstchar;
TokenInfo[tok::minus ] |= aci_custom_firstchar;
TokenInfo[tok::slash ] |= aci_custom_firstchar;
TokenInfo[tok::less ] |= aci_custom_firstchar;
TokenInfo[tok::greater ] |= aci_custom_firstchar;
TokenInfo[tok::pipe ] |= aci_custom_firstchar;
TokenInfo[tok::percent ] |= aci_custom_firstchar;
TokenInfo[tok::colon ] |= aci_custom_firstchar;
TokenInfo[tok::hash ] |= aci_custom_firstchar;
TokenInfo[tok::arrow ] |= aci_custom_firstchar;
// These tokens change behavior if followed by an '='.
TokenInfo[tok::amp ] |= aci_avoid_equal; // &=
TokenInfo[tok::plus ] |= aci_avoid_equal; // +=
TokenInfo[tok::minus ] |= aci_avoid_equal; // -=
TokenInfo[tok::slash ] |= aci_avoid_equal; // /=
TokenInfo[tok::less ] |= aci_avoid_equal; // <=
TokenInfo[tok::greater ] |= aci_avoid_equal; // >=
TokenInfo[tok::pipe ] |= aci_avoid_equal; // |=
TokenInfo[tok::percent ] |= aci_avoid_equal; // %=
TokenInfo[tok::star ] |= aci_avoid_equal; // *=
TokenInfo[tok::exclaim ] |= aci_avoid_equal; // !=
TokenInfo[tok::lessless ] |= aci_avoid_equal; // <<=
TokenInfo[tok::greatergreater] |= aci_avoid_equal; // >>=
TokenInfo[tok::caret ] |= aci_avoid_equal; // ^=
TokenInfo[tok::equal ] |= aci_avoid_equal; // ==
}
/// GetFirstChar - Get the first character of the token \arg Tok,
/// avoiding calls to getSpelling where possible.
static char GetFirstChar(Preprocessor &PP, const Token &Tok) {
if (IdentifierInfo *II = Tok.getIdentifierInfo()) {
// Avoid spelling identifiers, the most common form of token.
return II->getNameStart()[0];
} else if (!Tok.needsCleaning()) {
if (Tok.isLiteral() && Tok.getLiteralData()) {
return *Tok.getLiteralData();
} else {
SourceManager &SM = PP.getSourceManager();
return *SM.getCharacterData(SM.getSpellingLoc(Tok.getLocation()));
}
} else if (Tok.getLength() < 256) {
char Buffer[256];
const char *TokPtr = Buffer;
PP.getSpelling(Tok, TokPtr);
return TokPtr[0];
} else {
return PP.getSpelling(Tok)[0];
}
}
/// AvoidConcat - If printing PrevTok immediately followed by Tok would cause
/// the two individual tokens to be lexed as a single token, return true
/// (which causes a space to be printed between them). This allows the output
/// of -E mode to be lexed to the same token stream as lexing the input
/// directly would.
///
/// This code must conservatively return true if it doesn't want to be 100%
/// accurate. This will cause the output to include extra space characters,
/// but the resulting output won't have incorrect concatenations going on.
/// Examples include "..", which we print with a space between, because we
/// don't want to track enough to tell "x.." from "...".
bool TokenConcatenation::AvoidConcat(const Token &PrevPrevTok,
const Token &PrevTok,
const Token &Tok) const {
// First, check to see if the tokens were directly adjacent in the original
// source. If they were, it must be okay to stick them together: if there
// were an issue, the tokens would have been lexed differently.
if (PrevTok.getLocation().isFileID() && Tok.getLocation().isFileID() &&
PrevTok.getLocation().getFileLocWithOffset(PrevTok.getLength()) ==
Tok.getLocation())
return false;
tok::TokenKind PrevKind = PrevTok.getKind();
if (PrevTok.getIdentifierInfo()) // Language keyword or named operator.
PrevKind = tok::identifier;
// Look up information on when we should avoid concatenation with prevtok.
unsigned ConcatInfo = TokenInfo[PrevKind];
// If prevtok never causes a problem for anything after it, return quickly.
if (ConcatInfo == 0) return false;
if (ConcatInfo & aci_avoid_equal) {
// If the next token is '=' or '==', avoid concatenation.
if (Tok.is(tok::equal) || Tok.is(tok::equalequal))
return true;
ConcatInfo &= ~aci_avoid_equal;
}
if (ConcatInfo == 0) return false;
// Basic algorithm: we look at the first character of the second token, and
// determine whether it, if appended to the first token, would form (or
// would contribute) to a larger token if concatenated.
char FirstChar = 0;
if (ConcatInfo & aci_custom) {
// If the token does not need to know the first character, don't get it.
} else {
FirstChar = GetFirstChar(PP, Tok);
}
switch (PrevKind) {
default: assert(0 && "InitAvoidConcatTokenInfo built wrong");
case tok::identifier: // id+id or id+number or id+L"foo".
// id+'.'... will not append.
if (Tok.is(tok::numeric_constant))
return GetFirstChar(PP, Tok) != '.';
if (Tok.getIdentifierInfo() || Tok.is(tok::wide_string_literal) /* ||
Tok.is(tok::wide_char_literal)*/)
return true;
// If this isn't identifier + string, we're done.
if (Tok.isNot(tok::char_constant) && Tok.isNot(tok::string_literal))
return false;
// FIXME: need a wide_char_constant!
// If the string was a wide string L"foo" or wide char L'f', it would
// concat with the previous identifier into fooL"bar". Avoid this.
if (StartsWithL(Tok))
return true;
// Otherwise, this is a narrow character or string. If the *identifier*
// is a literal 'L', avoid pasting L "foo" -> L"foo".
return IsIdentifierL(PrevTok);
case tok::numeric_constant:
return isalnum(FirstChar) || Tok.is(tok::numeric_constant) ||
FirstChar == '+' || FirstChar == '-' || FirstChar == '.';
case tok::period: // ..., .*, .1234
return (FirstChar == '.' && PrevPrevTok.is(tok::period)) ||
isdigit(FirstChar) ||
(PP.getLangOptions().CPlusPlus && FirstChar == '*');
case tok::amp: // &&
return FirstChar == '&';
case tok::plus: // ++
return FirstChar == '+';
case tok::minus: // --, ->, ->*
return FirstChar == '-' || FirstChar == '>';
case tok::slash: //, /*, //
return FirstChar == '*' || FirstChar == '/';
case tok::less: // <<, <<=, <:, <%
return FirstChar == '<' || FirstChar == ':' || FirstChar == '%';
case tok::greater: // >>, >>=
return FirstChar == '>';
case tok::pipe: // ||
return FirstChar == '|';
case tok::percent: // %>, %:
return FirstChar == '>' || FirstChar == ':';
case tok::colon: // ::, :>
return FirstChar == '>' ||
(PP.getLangOptions().CPlusPlus && FirstChar == ':');
case tok::hash: // ##, #@, %:%:
return FirstChar == '#' || FirstChar == '@' || FirstChar == '%';
case tok::arrow: // ->*
return PP.getLangOptions().CPlusPlus && FirstChar == '*';
}
}