305 lines · cpp
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-exception6//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"17using namespace clang;18 19 20/// IsStringPrefix - Return true if Str is a string prefix.21/// 'L', 'u', 'U', or 'u8'. Including raw versions.22static 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't31 // 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 token46/// is literally 'L', 'u', 'U', or 'u8'. Including raw versions.47bool 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 69TokenConcatenation::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().CPlusPlus20)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.128static 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 cause150/// the two individual tokens to be lexed as a single token, return true151/// (which causes a space to be printed between them). This allows the output152/// of -E mode to be lexed to the same token stream as lexing the input153/// 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 we159/// don't want to track enough to tell "x.." from "...".160bool TokenConcatenation::AvoidConcat(const Token &PrevPrevTok,161 const Token &PrevTok,162 const Token &Tok) const {163 // No space is required between header unit name in quote and semi.164 if (PrevTok.is(tok::annot_header_unit) && Tok.is(tok::semi))165 return false;166 167 // Conservatively assume that every annotation token that has a printable168 // form requires whitespace.169 if (PrevTok.isAnnotation())170 return true;171 172 // First, check to see if the tokens were directly adjacent in the original173 // source. If they were, it must be okay to stick them together: if there174 // were an issue, the tokens would have been lexed differently.175 SourceManager &SM = PP.getSourceManager();176 SourceLocation PrevSpellLoc = SM.getSpellingLoc(PrevTok.getLocation());177 SourceLocation SpellLoc = SM.getSpellingLoc(Tok.getLocation());178 if (PrevSpellLoc.getLocWithOffset(PrevTok.getLength()) == SpellLoc)179 return false;180 181 tok::TokenKind PrevKind = PrevTok.getKind();182 if (!PrevTok.isAnnotation() && PrevTok.getIdentifierInfo())183 PrevKind = tok::identifier; // Language keyword or named operator.184 185 // Look up information on when we should avoid concatenation with prevtok.186 unsigned ConcatInfo = TokenInfo[PrevKind];187 188 // If prevtok never causes a problem for anything after it, return quickly.189 if (ConcatInfo == 0) return false;190 191 if (ConcatInfo & aci_avoid_equal) {192 // If the next token is '=' or '==', avoid concatenation.193 if (Tok.isOneOf(tok::equal, tok::equalequal))194 return true;195 ConcatInfo &= ~aci_avoid_equal;196 }197 if (Tok.isAnnotation()) {198 // Modules annotation can show up when generated automatically for includes.199 assert(Tok.isOneOf(tok::annot_module_include, tok::annot_module_begin,200 tok::annot_module_end, tok::annot_embed) &&201 "unexpected annotation in AvoidConcat");202 203 ConcatInfo = 0;204 if (Tok.is(tok::annot_embed))205 return true;206 }207 208 if (ConcatInfo == 0)209 return false;210 211 // Basic algorithm: we look at the first character of the second token, and212 // determine whether it, if appended to the first token, would form (or213 // would contribute) to a larger token if concatenated.214 char FirstChar = 0;215 if (ConcatInfo & aci_custom) {216 // If the token does not need to know the first character, don't get it.217 } else {218 FirstChar = GetFirstChar(PP, Tok);219 }220 221 switch (PrevKind) {222 default:223 llvm_unreachable("InitAvoidConcatTokenInfo built wrong");224 225 case tok::raw_identifier:226 llvm_unreachable("tok::raw_identifier in non-raw lexing mode!");227 228 case tok::string_literal:229 case tok::wide_string_literal:230 case tok::utf8_string_literal:231 case tok::utf16_string_literal:232 case tok::utf32_string_literal:233 case tok::char_constant:234 case tok::wide_char_constant:235 case tok::utf8_char_constant:236 case tok::utf16_char_constant:237 case tok::utf32_char_constant:238 if (!PP.getLangOpts().CPlusPlus11)239 return false;240 241 // In C++11, a string or character literal followed by an identifier is a242 // single token.243 if (Tok.getIdentifierInfo())244 return true;245 246 // A ud-suffix is an identifier. If the previous token ends with one, treat247 // it as an identifier.248 if (!PrevTok.hasUDSuffix())249 return false;250 [[fallthrough]];251 case tok::identifier: // id+id or id+number or id+L"foo".252 // id+'.'... will not append.253 if (Tok.is(tok::numeric_constant))254 return GetFirstChar(PP, Tok) != '.';255 256 if (Tok.getIdentifierInfo() ||257 Tok.isOneOf(tok::wide_string_literal, tok::utf8_string_literal,258 tok::utf16_string_literal, tok::utf32_string_literal,259 tok::wide_char_constant, tok::utf8_char_constant,260 tok::utf16_char_constant, tok::utf32_char_constant))261 return true;262 263 // If this isn't identifier + string, we're done.264 if (Tok.isNot(tok::char_constant) && Tok.isNot(tok::string_literal))265 return false;266 267 // Otherwise, this is a narrow character or string. If the *identifier*268 // is a literal 'L', 'u8', 'u' or 'U', avoid pasting L "foo" -> L"foo".269 return IsIdentifierStringPrefix(PrevTok);270 271 case tok::numeric_constant:272 return isPreprocessingNumberBody(FirstChar) ||273 FirstChar == '+' || FirstChar == '-';274 case tok::period: // ..., .*, .1234275 return (FirstChar == '.' && PrevPrevTok.is(tok::period)) ||276 isDigit(FirstChar) ||277 (PP.getLangOpts().CPlusPlus && FirstChar == '*');278 case tok::amp: // &&279 return FirstChar == '&';280 case tok::plus: // ++281 return FirstChar == '+';282 case tok::minus: // --, ->, ->*283 return FirstChar == '-' || FirstChar == '>';284 case tok::slash: //, /*, //285 return FirstChar == '*' || FirstChar == '/';286 case tok::less: // <<, <<=, <:, <%287 return FirstChar == '<' || FirstChar == ':' || FirstChar == '%';288 case tok::greater: // >>, >>=289 return FirstChar == '>';290 case tok::pipe: // ||291 return FirstChar == '|';292 case tok::percent: // %>, %:293 return FirstChar == '>' || FirstChar == ':';294 case tok::colon: // ::, :>295 return FirstChar == '>' ||296 (PP.getLangOpts().CPlusPlus && FirstChar == ':');297 case tok::hash: // ##, #@, %:%:298 return FirstChar == '#' || FirstChar == '@' || FirstChar == '%';299 case tok::arrow: // ->*300 return PP.getLangOpts().CPlusPlus && FirstChar == '*';301 case tok::lessequal: // <=> (C++2a)302 return PP.getLangOpts().CPlusPlus20 && FirstChar == '>';303 }304}305