lib/Lex/TokenConcatenation.cpp

   1 //===--- TokenConcatenation.cpp - Token Concatenation Avoidance -----------===//
   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 the TokenConcatenation class.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "clang/Lex/TokenConcatenation.h"
  15 #include "clang/Lex/Preprocessor.h"
  16 #include "llvm/Support/ErrorHandling.h"
  17 using namespace clang;
  18
  19
  20 /// StartsWithL - Return true if the spelling of this token starts with 'L'.
  21 bool TokenConcatenation::StartsWithL(const Token &Tok) const {
  22   if (!Tok.needsCleaning()) {
  23     SourceManager &SM = PP.getSourceManager();
  24     return *SM.getCharacterData(SM.getSpellingLoc(Tok.getLocation())) == 'L';
  25   }
  26
  27   if (Tok.getLength() < 256) {
  28     char Buffer[256];
  29     const char *TokPtr = Buffer;
  30     PP.getSpelling(Tok, TokPtr);
  31     return TokPtr[0] == 'L';
  32   }
  33
  34   return PP.getSpelling(Tok)[0] == 'L';
  35 }
  36
  37 /// IsIdentifierL - Return true if the spelling of this token is literally
  38 /// 'L'.
  39 bool TokenConcatenation::IsIdentifierL(const Token &Tok) const {
  40   if (!Tok.needsCleaning()) {
  41     if (Tok.getLength() != 1)
  42       return false;
  43     SourceManager &SM = PP.getSourceManager();
  44     return *SM.getCharacterData(SM.getSpellingLoc(Tok.getLocation())) == 'L';
  45   }
  46
  47   if (Tok.getLength() < 256) {
  48     char Buffer[256];
  49     const char *TokPtr = Buffer;
  50     if (PP.getSpelling(Tok, TokPtr) != 1)
  51       return false;
  52     return TokPtr[0] == 'L';
  53   }
  54
  55   return PP.getSpelling(Tok) == "L";
  56 }
  57
  58 TokenConcatenation::TokenConcatenation(Preprocessor &pp) : PP(pp) {
  59   memset(TokenInfo, 0, sizeof(TokenInfo));
  60
  61   // These tokens have custom code in AvoidConcat.
  62   TokenInfo[tok::identifier      ] |= aci_custom;
  63   TokenInfo[tok::numeric_constant] |= aci_custom_firstchar;
  64   TokenInfo[tok::period          ] |= aci_custom_firstchar;
  65   TokenInfo[tok::amp             ] |= aci_custom_firstchar;
  66   TokenInfo[tok::plus            ] |= aci_custom_firstchar;
  67   TokenInfo[tok::minus           ] |= aci_custom_firstchar;
  68   TokenInfo[tok::slash           ] |= aci_custom_firstchar;
  69   TokenInfo[tok::less            ] |= aci_custom_firstchar;
  70   TokenInfo[tok::greater         ] |= aci_custom_firstchar;
  71   TokenInfo[tok::pipe            ] |= aci_custom_firstchar;
  72   TokenInfo[tok::percent         ] |= aci_custom_firstchar;
  73   TokenInfo[tok::colon           ] |= aci_custom_firstchar;
  74   TokenInfo[tok::hash            ] |= aci_custom_firstchar;
  75   TokenInfo[tok::arrow           ] |= aci_custom_firstchar;
  76
  77   // These tokens change behavior if followed by an '='.
  78   TokenInfo[tok::amp         ] |= aci_avoid_equal;           // &=
  79   TokenInfo[tok::plus        ] |= aci_avoid_equal;           // +=
  80   TokenInfo[tok::minus       ] |= aci_avoid_equal;           // -=
  81   TokenInfo[tok::slash       ] |= aci_avoid_equal;           // /=
  82   TokenInfo[tok::less        ] |= aci_avoid_equal;           // <=
  83   TokenInfo[tok::greater     ] |= aci_avoid_equal;           // >=
  84   TokenInfo[tok::pipe        ] |= aci_avoid_equal;           // |=
  85   TokenInfo[tok::percent     ] |= aci_avoid_equal;           // %=
  86   TokenInfo[tok::star        ] |= aci_avoid_equal;           // *=
  87   TokenInfo[tok::exclaim     ] |= aci_avoid_equal;           // !=
  88   TokenInfo[tok::lessless    ] |= aci_avoid_equal;           // <<=
  89   TokenInfo[tok::greatergreater] |= aci_avoid_equal;         // >>=
  90   TokenInfo[tok::caret       ] |= aci_avoid_equal;           // ^=
  91   TokenInfo[tok::equal       ] |= aci_avoid_equal;           // ==
  92 }
  93
  94 /// GetFirstChar - Get the first character of the token \arg Tok,
  95 /// avoiding calls to getSpelling where possible.
  96 static char GetFirstChar(Preprocessor &PP, const Token &Tok) {
  97   if (IdentifierInfo *II = Tok.getIdentifierInfo()) {
  98     // Avoid spelling identifiers, the most common form of token.
  99     return II->getNameStart()[0];
 100   } else if (!Tok.needsCleaning()) {
 101     if (Tok.isLiteral() && Tok.getLiteralData()) {
 102       return *Tok.getLiteralData();
 103     } else {
 104       SourceManager &SM = PP.getSourceManager();
 105       return *SM.getCharacterData(SM.getSpellingLoc(Tok.getLocation()));
 106     }
 107   } else if (Tok.getLength() < 256) {
 108     char Buffer[256];
 109     const char *TokPtr = Buffer;
 110     PP.getSpelling(Tok, TokPtr);
 111     return TokPtr[0];
 112   } else {
 113     return PP.getSpelling(Tok)[0];
 114   }
 115 }
 116
 117 /// AvoidConcat - If printing PrevTok immediately followed by Tok would cause
 118 /// the two individual tokens to be lexed as a single token, return true
 119 /// (which causes a space to be printed between them).  This allows the output
 120 /// of -E mode to be lexed to the same token stream as lexing the input
 121 /// directly would.
 122 ///
 123 /// This code must conservatively return true if it doesn't want to be 100%
 124 /// accurate.  This will cause the output to include extra space characters,
 125 /// but the resulting output won't have incorrect concatenations going on.
 126 /// Examples include "..", which we print with a space between, because we
 127 /// don't want to track enough to tell "x.." from "...".
 128 bool TokenConcatenation::AvoidConcat(const Token &PrevPrevTok,
 129                                      const Token &PrevTok,
 130                                      const Token &Tok) const {
 131   // First, check to see if the tokens were directly adjacent in the original
 132   // source.  If they were, it must be okay to stick them together: if there
 133   // were an issue, the tokens would have been lexed differently.
 134   if (PrevTok.getLocation().isFileID() && Tok.getLocation().isFileID() &&
 135       PrevTok.getLocation().getFileLocWithOffset(PrevTok.getLength()) ==
 136         Tok.getLocation())
 137     return false;
 138
 139   tok::TokenKind PrevKind = PrevTok.getKind();
 140   if (PrevTok.getIdentifierInfo())  // Language keyword or named operator.
 141     PrevKind = tok::identifier;
 142
 143   // Look up information on when we should avoid concatenation with prevtok.
 144   unsigned ConcatInfo = TokenInfo[PrevKind];
 145
 146   // If prevtok never causes a problem for anything after it, return quickly.
 147   if (ConcatInfo == 0) return false;
 148
 149   if (ConcatInfo & aci_avoid_equal) {
 150     // If the next token is '=' or '==', avoid concatenation.
 151     if (Tok.is(tok::equal) || Tok.is(tok::equalequal))
 152       return true;
 153     ConcatInfo &= ~aci_avoid_equal;
 154   }
 155
 156   if (ConcatInfo == 0) return false;
 157
 158   // Basic algorithm: we look at the first character of the second token, and
 159   // determine whether it, if appended to the first token, would form (or
 160   // would contribute) to a larger token if concatenated.
 161   char FirstChar = 0;
 162   if (ConcatInfo & aci_custom) {
 163     // If the token does not need to know the first character, don't get it.
 164   } else {
 165     FirstChar = GetFirstChar(PP, Tok);
 166   }
 167
 168   switch (PrevKind) {
 169   default:
 170     llvm_unreachable("InitAvoidConcatTokenInfo built wrong");
 171     return true;
 172
 173   case tok::raw_identifier:
 174     llvm_unreachable("tok::raw_identifier in non-raw lexing mode!");
 175     return true;
 176
 177   case tok::identifier:   // id+id or id+number or id+L"foo".
 178     // id+'.'... will not append.
 179     if (Tok.is(tok::numeric_constant))
 180       return GetFirstChar(PP, Tok) != '.';
 181
 182     if (Tok.getIdentifierInfo() || Tok.is(tok::wide_string_literal) /* ||
 183      Tok.is(tok::wide_char_literal)*/)
 184       return true;
 185
 186     // If this isn't identifier + string, we're done.
 187     if (Tok.isNot(tok::char_constant) && Tok.isNot(tok::string_literal))
 188       return false;
 189
 190     // FIXME: need a wide_char_constant!
 191
 192     // If the string was a wide string L"foo" or wide char L'f', it would
 193     // concat with the previous identifier into fooL"bar".  Avoid this.
 194     if (StartsWithL(Tok))
 195       return true;
 196
 197     // Otherwise, this is a narrow character or string.  If the *identifier*
 198     // is a literal 'L', avoid pasting L "foo" -> L"foo".
 199     return IsIdentifierL(PrevTok);
 200   case tok::numeric_constant:
 201     return isalnum(FirstChar) || Tok.is(tok::numeric_constant) ||
 202     FirstChar == '+' || FirstChar == '-' || FirstChar == '.';
 203   case tok::period:          // ..., .*, .1234
 204     return (FirstChar == '.' && PrevPrevTok.is(tok::period)) ||
 205     isdigit(FirstChar) ||
 206     (PP.getLangOptions().CPlusPlus && FirstChar == '*');
 207   case tok::amp:             // &&
 208     return FirstChar == '&';
 209   case tok::plus:            // ++
 210     return FirstChar == '+';
 211   case tok::minus:           // --, ->, ->*
 212     return FirstChar == '-' || FirstChar == '>';
 213   case tok::slash:           //, /*, //
 214     return FirstChar == '*' || FirstChar == '/';
 215   case tok::less:            // <<, <<=, <:, <%
 216     return FirstChar == '<' || FirstChar == ':' || FirstChar == '%';
 217   case tok::greater:         // >>, >>=
 218     return FirstChar == '>';
 219   case tok::pipe:            // ||
 220     return FirstChar == '|';
 221   case tok::percent:         // %>, %:
 222     return FirstChar == '>' || FirstChar == ':';
 223   case tok::colon:           // ::, :>
 224     return FirstChar == '>' ||
 225     (PP.getLangOptions().CPlusPlus && FirstChar == ':');
 226   case tok::hash:            // ##, #@, %:%:
 227     return FirstChar == '#' || FirstChar == '@' || FirstChar == '%';
 228   case tok::arrow:           // ->*
 229     return PP.getLangOptions().CPlusPlus && FirstChar == '*';
 230   }
 231 }