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llvm-project/clang/lib/Lex/TokenConcatenation.cpp

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//===--- TokenConcatenation.cpp - Token Concatenation Avoidance -----------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the TokenConcatenation class.
//
//===----------------------------------------------------------------------===//
#include "clang/Lex/TokenConcatenation.h"
#include "clang/Basic/CharInfo.h"
#include "clang/Lex/Preprocessor.h"
#include "llvm/Support/ErrorHandling.h"
using namespace clang;
/// IsStringPrefix - Return true if Str is a string prefix.
/// 'L', 'u', 'U', or 'u8'. Including raw versions.
static bool IsStringPrefix(StringRef Str, bool CPlusPlus11) {
if (Str[0] == 'L' ||
(CPlusPlus11 && (Str[0] == 'u' || Str[0] == 'U' || Str[0] == 'R'))) {
if (Str.size() == 1)
return true; // "L", "u", "U", and "R"
// Check for raw flavors. Need to make sure the first character wasn't
// already R. Need CPlusPlus11 check for "LR".
if (Str[1] == 'R' && Str[0] != 'R' && Str.size() == 2 && CPlusPlus11)
return true; // "LR", "uR", "UR"
// Check for "u8" and "u8R"
if (Str[0] == 'u' && Str[1] == '8') {
if (Str.size() == 2) return true; // "u8"
if (Str.size() == 3 && Str[2] == 'R') return true; // "u8R"
}
}
return false;
}
/// IsIdentifierStringPrefix - Return true if the spelling of the token
/// is literally 'L', 'u', 'U', or 'u8'. Including raw versions.
bool TokenConcatenation::IsIdentifierStringPrefix(const Token &Tok) const {
const LangOptions &LangOpts = PP.getLangOpts();
if (!Tok.needsCleaning()) {
if (Tok.getLength() < 1 || Tok.getLength() > 3)
return false;
SourceManager &SM = PP.getSourceManager();
const char *Ptr = SM.getCharacterData(SM.getSpellingLoc(Tok.getLocation()));
return IsStringPrefix(StringRef(Ptr, Tok.getLength()),
LangOpts.CPlusPlus11);
}
if (Tok.getLength() < 256) {
char Buffer[256];
const char *TokPtr = Buffer;
unsigned length = PP.getSpelling(Tok, TokPtr);
return IsStringPrefix(StringRef(TokPtr, length), LangOpts.CPlusPlus11);
}
return IsStringPrefix(StringRef(PP.getSpelling(Tok)), LangOpts.CPlusPlus11);
}
TokenConcatenation::TokenConcatenation(const 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 have custom code in C++11 mode.
if (PP.getLangOpts().CPlusPlus11) {
TokenInfo[tok::string_literal ] |= aci_custom;
TokenInfo[tok::wide_string_literal ] |= aci_custom;
TokenInfo[tok::utf8_string_literal ] |= aci_custom;
TokenInfo[tok::utf16_string_literal] |= aci_custom;
TokenInfo[tok::utf32_string_literal] |= aci_custom;
TokenInfo[tok::char_constant ] |= aci_custom;
TokenInfo[tok::wide_char_constant ] |= aci_custom;
TokenInfo[tok::utf16_char_constant ] |= aci_custom;
TokenInfo[tok::utf32_char_constant ] |= aci_custom;
}
// These tokens have custom code in C++17 mode.
if (PP.getLangOpts().CPlusPlus17)
TokenInfo[tok::utf8_char_constant] |= aci_custom;
// These tokens have custom code in C++2a mode.
if (PP.getLangOpts().CPlusPlus2a)
TokenInfo[tok::lessequal ] |= 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(const 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 {
// Conservatively assume that every annotation token that has a printable
// form requires whitespace.
if (PrevTok.isAnnotation())
return true;
// 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.
SourceManager &SM = PP.getSourceManager();
SourceLocation PrevSpellLoc = SM.getSpellingLoc(PrevTok.getLocation());
SourceLocation SpellLoc = SM.getSpellingLoc(Tok.getLocation());
if (PrevSpellLoc.getLocWithOffset(PrevTok.getLength()) == SpellLoc)
return false;
tok::TokenKind PrevKind = PrevTok.getKind();
if (!PrevTok.isAnnotation() && PrevTok.getIdentifierInfo())
PrevKind = tok::identifier; // Language keyword or named operator.
// 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.isOneOf(tok::equal, tok::equalequal))
return true;
ConcatInfo &= ~aci_avoid_equal;
}
if (Tok.isAnnotation()) {
// Modules annotation can show up when generated automatically for includes.
assert(Tok.isOneOf(tok::annot_module_include, tok::annot_module_begin,
tok::annot_module_end) &&
"unexpected annotation in AvoidConcat");
ConcatInfo = 0;
}
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:
llvm_unreachable("InitAvoidConcatTokenInfo built wrong");
case tok::raw_identifier:
llvm_unreachable("tok::raw_identifier in non-raw lexing mode!");
case tok::string_literal:
case tok::wide_string_literal:
case tok::utf8_string_literal:
case tok::utf16_string_literal:
case tok::utf32_string_literal:
case tok::char_constant:
case tok::wide_char_constant:
case tok::utf8_char_constant:
case tok::utf16_char_constant:
case tok::utf32_char_constant:
if (!PP.getLangOpts().CPlusPlus11)
return false;
// In C++11, a string or character literal followed by an identifier is a
// single token.
if (Tok.getIdentifierInfo())
return true;
// A ud-suffix is an identifier. If the previous token ends with one, treat
// it as an identifier.
if (!PrevTok.hasUDSuffix())
return false;
LLVM_FALLTHROUGH;
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.isOneOf(tok::wide_string_literal, tok::utf8_string_literal,
tok::utf16_string_literal, tok::utf32_string_literal,
tok::wide_char_constant, tok::utf8_char_constant,
tok::utf16_char_constant, tok::utf32_char_constant))
return true;
// If this isn't identifier + string, we're done.
if (Tok.isNot(tok::char_constant) && Tok.isNot(tok::string_literal))
return false;
// Otherwise, this is a narrow character or string. If the *identifier*
// is a literal 'L', 'u8', 'u' or 'U', avoid pasting L "foo" -> L"foo".
return IsIdentifierStringPrefix(PrevTok);
case tok::numeric_constant:
return isPreprocessingNumberBody(FirstChar) ||
FirstChar == '+' || FirstChar == '-';
case tok::period: // ..., .*, .1234
return (FirstChar == '.' && PrevPrevTok.is(tok::period)) ||
isDigit(FirstChar) ||
(PP.getLangOpts().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.getLangOpts().CPlusPlus && FirstChar == ':');
case tok::hash: // ##, #@, %:%:
return FirstChar == '#' || FirstChar == '@' || FirstChar == '%';
case tok::arrow: // ->*
return PP.getLangOpts().CPlusPlus && FirstChar == '*';
case tok::lessequal: // <=> (C++2a)
return PP.getLangOpts().CPlusPlus2a && FirstChar == '>';
}
}
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