1 //===--- TokenConcatenation.cpp - Token Concatenation Avoidance -----------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file implements the TokenConcatenation class. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "clang/Lex/TokenConcatenation.h" 14 #include "clang/Basic/CharInfo.h" 15 #include "clang/Lex/Preprocessor.h" 16 #include "llvm/Support/ErrorHandling.h" 17 using namespace clang; 18 19 20 /// IsStringPrefix - Return true if Str is a string prefix. 21 /// 'L', 'u', 'U', or 'u8'. Including raw versions. 22 static bool IsStringPrefix(StringRef Str, bool CPlusPlus11) { 23 24 if (Str[0] == 'L' || 25 (CPlusPlus11 && (Str[0] == 'u' || Str[0] == 'U' || Str[0] == 'R'))) { 26 27 if (Str.size() == 1) 28 return true; // "L", "u", "U", and "R" 29 30 // Check for raw flavors. Need to make sure the first character wasn't 31 // already R. Need CPlusPlus11 check for "LR". 32 if (Str[1] == 'R' && Str[0] != 'R' && Str.size() == 2 && CPlusPlus11) 33 return true; // "LR", "uR", "UR" 34 35 // Check for "u8" and "u8R" 36 if (Str[0] == 'u' && Str[1] == '8') { 37 if (Str.size() == 2) return true; // "u8" 38 if (Str.size() == 3 && Str[2] == 'R') return true; // "u8R" 39 } 40 } 41 42 return false; 43 } 44 45 /// IsIdentifierStringPrefix - Return true if the spelling of the token 46 /// is literally 'L', 'u', 'U', or 'u8'. Including raw versions. 47 bool TokenConcatenation::IsIdentifierStringPrefix(const Token &Tok) const { 48 const LangOptions &LangOpts = PP.getLangOpts(); 49 50 if (!Tok.needsCleaning()) { 51 if (Tok.getLength() < 1 || Tok.getLength() > 3) 52 return false; 53 SourceManager &SM = PP.getSourceManager(); 54 const char *Ptr = SM.getCharacterData(SM.getSpellingLoc(Tok.getLocation())); 55 return IsStringPrefix(StringRef(Ptr, Tok.getLength()), 56 LangOpts.CPlusPlus11); 57 } 58 59 if (Tok.getLength() < 256) { 60 char Buffer[256]; 61 const char *TokPtr = Buffer; 62 unsigned length = PP.getSpelling(Tok, TokPtr); 63 return IsStringPrefix(StringRef(TokPtr, length), LangOpts.CPlusPlus11); 64 } 65 66 return IsStringPrefix(StringRef(PP.getSpelling(Tok)), LangOpts.CPlusPlus11); 67 } 68 69 TokenConcatenation::TokenConcatenation(const Preprocessor &pp) : PP(pp) { 70 memset(TokenInfo, 0, sizeof(TokenInfo)); 71 72 // These tokens have custom code in AvoidConcat. 73 TokenInfo[tok::identifier ] |= aci_custom; 74 TokenInfo[tok::numeric_constant] |= aci_custom_firstchar; 75 TokenInfo[tok::period ] |= aci_custom_firstchar; 76 TokenInfo[tok::amp ] |= aci_custom_firstchar; 77 TokenInfo[tok::plus ] |= aci_custom_firstchar; 78 TokenInfo[tok::minus ] |= aci_custom_firstchar; 79 TokenInfo[tok::slash ] |= aci_custom_firstchar; 80 TokenInfo[tok::less ] |= aci_custom_firstchar; 81 TokenInfo[tok::greater ] |= aci_custom_firstchar; 82 TokenInfo[tok::pipe ] |= aci_custom_firstchar; 83 TokenInfo[tok::percent ] |= aci_custom_firstchar; 84 TokenInfo[tok::colon ] |= aci_custom_firstchar; 85 TokenInfo[tok::hash ] |= aci_custom_firstchar; 86 TokenInfo[tok::arrow ] |= aci_custom_firstchar; 87 88 // These tokens have custom code in C++11 mode. 89 if (PP.getLangOpts().CPlusPlus11) { 90 TokenInfo[tok::string_literal ] |= aci_custom; 91 TokenInfo[tok::wide_string_literal ] |= aci_custom; 92 TokenInfo[tok::utf8_string_literal ] |= aci_custom; 93 TokenInfo[tok::utf16_string_literal] |= aci_custom; 94 TokenInfo[tok::utf32_string_literal] |= aci_custom; 95 TokenInfo[tok::char_constant ] |= aci_custom; 96 TokenInfo[tok::wide_char_constant ] |= aci_custom; 97 TokenInfo[tok::utf16_char_constant ] |= aci_custom; 98 TokenInfo[tok::utf32_char_constant ] |= aci_custom; 99 } 100 101 // These tokens have custom code in C++17 mode. 102 if (PP.getLangOpts().CPlusPlus17) 103 TokenInfo[tok::utf8_char_constant] |= aci_custom; 104 105 // These tokens have custom code in C++2a mode. 106 if (PP.getLangOpts().CPlusPlus2a) 107 TokenInfo[tok::lessequal ] |= aci_custom_firstchar; 108 109 // These tokens change behavior if followed by an '='. 110 TokenInfo[tok::amp ] |= aci_avoid_equal; // &= 111 TokenInfo[tok::plus ] |= aci_avoid_equal; // += 112 TokenInfo[tok::minus ] |= aci_avoid_equal; // -= 113 TokenInfo[tok::slash ] |= aci_avoid_equal; // /= 114 TokenInfo[tok::less ] |= aci_avoid_equal; // <= 115 TokenInfo[tok::greater ] |= aci_avoid_equal; // >= 116 TokenInfo[tok::pipe ] |= aci_avoid_equal; // |= 117 TokenInfo[tok::percent ] |= aci_avoid_equal; // %= 118 TokenInfo[tok::star ] |= aci_avoid_equal; // *= 119 TokenInfo[tok::exclaim ] |= aci_avoid_equal; // != 120 TokenInfo[tok::lessless ] |= aci_avoid_equal; // <<= 121 TokenInfo[tok::greatergreater] |= aci_avoid_equal; // >>= 122 TokenInfo[tok::caret ] |= aci_avoid_equal; // ^= 123 TokenInfo[tok::equal ] |= aci_avoid_equal; // == 124 } 125 126 /// GetFirstChar - Get the first character of the token \arg Tok, 127 /// avoiding calls to getSpelling where possible. 128 static char GetFirstChar(const Preprocessor &PP, const Token &Tok) { 129 if (IdentifierInfo *II = Tok.getIdentifierInfo()) { 130 // Avoid spelling identifiers, the most common form of token. 131 return II->getNameStart()[0]; 132 } else if (!Tok.needsCleaning()) { 133 if (Tok.isLiteral() && Tok.getLiteralData()) { 134 return *Tok.getLiteralData(); 135 } else { 136 SourceManager &SM = PP.getSourceManager(); 137 return *SM.getCharacterData(SM.getSpellingLoc(Tok.getLocation())); 138 } 139 } else if (Tok.getLength() < 256) { 140 char Buffer[256]; 141 const char *TokPtr = Buffer; 142 PP.getSpelling(Tok, TokPtr); 143 return TokPtr[0]; 144 } else { 145 return PP.getSpelling(Tok)[0]; 146 } 147 } 148 149 /// AvoidConcat - If printing PrevTok immediately followed by Tok would cause 150 /// the two individual tokens to be lexed as a single token, return true 151 /// (which causes a space to be printed between them). This allows the output 152 /// of -E mode to be lexed to the same token stream as lexing the input 153 /// directly would. 154 /// 155 /// This code must conservatively return true if it doesn't want to be 100% 156 /// accurate. This will cause the output to include extra space characters, 157 /// but the resulting output won't have incorrect concatenations going on. 158 /// Examples include "..", which we print with a space between, because we 159 /// don't want to track enough to tell "x.." from "...". 160 bool TokenConcatenation::AvoidConcat(const Token &PrevPrevTok, 161 const Token &PrevTok, 162 const Token &Tok) const { 163 // First, check to see if the tokens were directly adjacent in the original 164 // source. If they were, it must be okay to stick them together: if there 165 // were an issue, the tokens would have been lexed differently. 166 SourceManager &SM = PP.getSourceManager(); 167 SourceLocation PrevSpellLoc = SM.getSpellingLoc(PrevTok.getLocation()); 168 SourceLocation SpellLoc = SM.getSpellingLoc(Tok.getLocation()); 169 if (PrevSpellLoc.getLocWithOffset(PrevTok.getLength()) == SpellLoc) 170 return false; 171 172 tok::TokenKind PrevKind = PrevTok.getKind(); 173 if (!PrevTok.isAnnotation() && PrevTok.getIdentifierInfo()) 174 PrevKind = tok::identifier; // Language keyword or named operator. 175 176 // Look up information on when we should avoid concatenation with prevtok. 177 unsigned ConcatInfo = TokenInfo[PrevKind]; 178 179 // If prevtok never causes a problem for anything after it, return quickly. 180 if (ConcatInfo == 0) return false; 181 182 if (ConcatInfo & aci_avoid_equal) { 183 // If the next token is '=' or '==', avoid concatenation. 184 if (Tok.isOneOf(tok::equal, tok::equalequal)) 185 return true; 186 ConcatInfo &= ~aci_avoid_equal; 187 } 188 if (Tok.isAnnotation()) { 189 // Modules annotation can show up when generated automatically for includes. 190 assert(Tok.isOneOf(tok::annot_module_include, tok::annot_module_begin, 191 tok::annot_module_end) && 192 "unexpected annotation in AvoidConcat"); 193 ConcatInfo = 0; 194 } 195 196 if (ConcatInfo == 0) 197 return false; 198 199 // Basic algorithm: we look at the first character of the second token, and 200 // determine whether it, if appended to the first token, would form (or 201 // would contribute) to a larger token if concatenated. 202 char FirstChar = 0; 203 if (ConcatInfo & aci_custom) { 204 // If the token does not need to know the first character, don't get it. 205 } else { 206 FirstChar = GetFirstChar(PP, Tok); 207 } 208 209 switch (PrevKind) { 210 default: 211 llvm_unreachable("InitAvoidConcatTokenInfo built wrong"); 212 213 case tok::raw_identifier: 214 llvm_unreachable("tok::raw_identifier in non-raw lexing mode!"); 215 216 case tok::string_literal: 217 case tok::wide_string_literal: 218 case tok::utf8_string_literal: 219 case tok::utf16_string_literal: 220 case tok::utf32_string_literal: 221 case tok::char_constant: 222 case tok::wide_char_constant: 223 case tok::utf8_char_constant: 224 case tok::utf16_char_constant: 225 case tok::utf32_char_constant: 226 if (!PP.getLangOpts().CPlusPlus11) 227 return false; 228 229 // In C++11, a string or character literal followed by an identifier is a 230 // single token. 231 if (Tok.getIdentifierInfo()) 232 return true; 233 234 // A ud-suffix is an identifier. If the previous token ends with one, treat 235 // it as an identifier. 236 if (!PrevTok.hasUDSuffix()) 237 return false; 238 LLVM_FALLTHROUGH; 239 case tok::identifier: // id+id or id+number or id+L"foo". 240 // id+'.'... will not append. 241 if (Tok.is(tok::numeric_constant)) 242 return GetFirstChar(PP, Tok) != '.'; 243 244 if (Tok.getIdentifierInfo() || 245 Tok.isOneOf(tok::wide_string_literal, tok::utf8_string_literal, 246 tok::utf16_string_literal, tok::utf32_string_literal, 247 tok::wide_char_constant, tok::utf8_char_constant, 248 tok::utf16_char_constant, tok::utf32_char_constant)) 249 return true; 250 251 // If this isn't identifier + string, we're done. 252 if (Tok.isNot(tok::char_constant) && Tok.isNot(tok::string_literal)) 253 return false; 254 255 // Otherwise, this is a narrow character or string. If the *identifier* 256 // is a literal 'L', 'u8', 'u' or 'U', avoid pasting L "foo" -> L"foo". 257 return IsIdentifierStringPrefix(PrevTok); 258 259 case tok::numeric_constant: 260 return isPreprocessingNumberBody(FirstChar) || 261 FirstChar == '+' || FirstChar == '-'; 262 case tok::period: // ..., .*, .1234 263 return (FirstChar == '.' && PrevPrevTok.is(tok::period)) || 264 isDigit(FirstChar) || 265 (PP.getLangOpts().CPlusPlus && FirstChar == '*'); 266 case tok::amp: // && 267 return FirstChar == '&'; 268 case tok::plus: // ++ 269 return FirstChar == '+'; 270 case tok::minus: // --, ->, ->* 271 return FirstChar == '-' || FirstChar == '>'; 272 case tok::slash: //, /*, // 273 return FirstChar == '*' || FirstChar == '/'; 274 case tok::less: // <<, <<=, <:, <% 275 return FirstChar == '<' || FirstChar == ':' || FirstChar == '%'; 276 case tok::greater: // >>, >>= 277 return FirstChar == '>'; 278 case tok::pipe: // || 279 return FirstChar == '|'; 280 case tok::percent: // %>, %: 281 return FirstChar == '>' || FirstChar == ':'; 282 case tok::colon: // ::, :> 283 return FirstChar == '>' || 284 (PP.getLangOpts().CPlusPlus && FirstChar == ':'); 285 case tok::hash: // ##, #@, %:%: 286 return FirstChar == '#' || FirstChar == '@' || FirstChar == '%'; 287 case tok::arrow: // ->* 288 return PP.getLangOpts().CPlusPlus && FirstChar == '*'; 289 case tok::lessequal: // <=> (C++2a) 290 return PP.getLangOpts().CPlusPlus2a && FirstChar == '>'; 291 } 292 } 293