clang  16.0.0git
TokenConcatenation.cpp
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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().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.
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  // Conservatively assume that every annotation token that has a printable
164  // form requires whitespace.
165  if (PrevTok.isAnnotation())
166  return true;
167 
168  // First, check to see if the tokens were directly adjacent in the original
169  // source. If they were, it must be okay to stick them together: if there
170  // were an issue, the tokens would have been lexed differently.
171  SourceManager &SM = PP.getSourceManager();
172  SourceLocation PrevSpellLoc = SM.getSpellingLoc(PrevTok.getLocation());
173  SourceLocation SpellLoc = SM.getSpellingLoc(Tok.getLocation());
174  if (PrevSpellLoc.getLocWithOffset(PrevTok.getLength()) == SpellLoc)
175  return false;
176 
177  tok::TokenKind PrevKind = PrevTok.getKind();
178  if (!PrevTok.isAnnotation() && PrevTok.getIdentifierInfo())
179  PrevKind = tok::identifier; // Language keyword or named operator.
180 
181  // Look up information on when we should avoid concatenation with prevtok.
182  unsigned ConcatInfo = TokenInfo[PrevKind];
183 
184  // If prevtok never causes a problem for anything after it, return quickly.
185  if (ConcatInfo == 0) return false;
186 
187  if (ConcatInfo & aci_avoid_equal) {
188  // If the next token is '=' or '==', avoid concatenation.
189  if (Tok.isOneOf(tok::equal, tok::equalequal))
190  return true;
191  ConcatInfo &= ~aci_avoid_equal;
192  }
193  if (Tok.isAnnotation()) {
194  // Modules annotation can show up when generated automatically for includes.
195  assert(Tok.isOneOf(tok::annot_module_include, tok::annot_module_begin,
196  tok::annot_module_end) &&
197  "unexpected annotation in AvoidConcat");
198  ConcatInfo = 0;
199  }
200 
201  if (ConcatInfo == 0)
202  return false;
203 
204  // Basic algorithm: we look at the first character of the second token, and
205  // determine whether it, if appended to the first token, would form (or
206  // would contribute) to a larger token if concatenated.
207  char FirstChar = 0;
208  if (ConcatInfo & aci_custom) {
209  // If the token does not need to know the first character, don't get it.
210  } else {
211  FirstChar = GetFirstChar(PP, Tok);
212  }
213 
214  switch (PrevKind) {
215  default:
216  llvm_unreachable("InitAvoidConcatTokenInfo built wrong");
217 
218  case tok::raw_identifier:
219  llvm_unreachable("tok::raw_identifier in non-raw lexing mode!");
220 
221  case tok::string_literal:
222  case tok::wide_string_literal:
223  case tok::utf8_string_literal:
224  case tok::utf16_string_literal:
225  case tok::utf32_string_literal:
226  case tok::char_constant:
227  case tok::wide_char_constant:
228  case tok::utf8_char_constant:
229  case tok::utf16_char_constant:
230  case tok::utf32_char_constant:
231  if (!PP.getLangOpts().CPlusPlus11)
232  return false;
233 
234  // In C++11, a string or character literal followed by an identifier is a
235  // single token.
236  if (Tok.getIdentifierInfo())
237  return true;
238 
239  // A ud-suffix is an identifier. If the previous token ends with one, treat
240  // it as an identifier.
241  if (!PrevTok.hasUDSuffix())
242  return false;
243  [[fallthrough]];
244  case tok::identifier: // id+id or id+number or id+L"foo".
245  // id+'.'... will not append.
246  if (Tok.is(tok::numeric_constant))
247  return GetFirstChar(PP, Tok) != '.';
248 
249  if (Tok.getIdentifierInfo() ||
250  Tok.isOneOf(tok::wide_string_literal, tok::utf8_string_literal,
251  tok::utf16_string_literal, tok::utf32_string_literal,
252  tok::wide_char_constant, tok::utf8_char_constant,
253  tok::utf16_char_constant, tok::utf32_char_constant))
254  return true;
255 
256  // If this isn't identifier + string, we're done.
257  if (Tok.isNot(tok::char_constant) && Tok.isNot(tok::string_literal))
258  return false;
259 
260  // Otherwise, this is a narrow character or string. If the *identifier*
261  // is a literal 'L', 'u8', 'u' or 'U', avoid pasting L "foo" -> L"foo".
262  return IsIdentifierStringPrefix(PrevTok);
263 
264  case tok::numeric_constant:
265  return isPreprocessingNumberBody(FirstChar) ||
266  FirstChar == '+' || FirstChar == '-';
267  case tok::period: // ..., .*, .1234
268  return (FirstChar == '.' && PrevPrevTok.is(tok::period)) ||
269  isDigit(FirstChar) ||
270  (PP.getLangOpts().CPlusPlus && FirstChar == '*');
271  case tok::amp: // &&
272  return FirstChar == '&';
273  case tok::plus: // ++
274  return FirstChar == '+';
275  case tok::minus: // --, ->, ->*
276  return FirstChar == '-' || FirstChar == '>';
277  case tok::slash: //, /*, //
278  return FirstChar == '*' || FirstChar == '/';
279  case tok::less: // <<, <<=, <:, <%
280  return FirstChar == '<' || FirstChar == ':' || FirstChar == '%';
281  case tok::greater: // >>, >>=
282  return FirstChar == '>';
283  case tok::pipe: // ||
284  return FirstChar == '|';
285  case tok::percent: // %>, %:
286  return FirstChar == '>' || FirstChar == ':';
287  case tok::colon: // ::, :>
288  return FirstChar == '>' ||
289  (PP.getLangOpts().CPlusPlus && FirstChar == ':');
290  case tok::hash: // ##, #@, %:%:
291  return FirstChar == '#' || FirstChar == '@' || FirstChar == '%';
292  case tok::arrow: // ->*
293  return PP.getLangOpts().CPlusPlus && FirstChar == '*';
294  case tok::lessequal: // <=> (C++2a)
295  return PP.getLangOpts().CPlusPlus20 && FirstChar == '>';
296  }
297 }
GetFirstChar
static char GetFirstChar(const Preprocessor &PP, const Token &Tok)
GetFirstChar - Get the first character of the token.
Definition: TokenConcatenation.cpp:128
clang::Token::getLiteralData
const char * getLiteralData() const
getLiteralData - For a literal token (numeric constant, string, etc), this returns a pointer to the s...
Definition: Token.h:219
clang::SourceLocation
Encodes a location in the source.
Definition: SourceLocation.h:86
clang::SourceLocation::getLocWithOffset
SourceLocation getLocWithOffset(IntTy Offset) const
Return a source location with the specified offset from this SourceLocation.
Definition: SourceLocation.h:134
clang::Token::getIdentifierInfo
IdentifierInfo * getIdentifierInfo() const
Definition: Token.h:181
IsStringPrefix
static bool IsStringPrefix(StringRef Str, bool CPlusPlus11)
IsStringPrefix - Return true if Str is a string prefix.
Definition: TokenConcatenation.cpp:22
TokenConcatenation.h
clang::Token
Token - This structure provides full information about a lexed token.
Definition: Token.h:35
clang::isPreprocessingNumberBody
LLVM_READONLY bool isPreprocessingNumberBody(unsigned char c)
Return true if this is the body character of a C preprocessing number, which is [a-zA-Z0-9_.
Definition: CharInfo.h:153
clang::SourceManager
This class handles loading and caching of source files into memory.
Definition: SourceManager.h:637
clang::Preprocessor::getLangOpts
const LangOptions & getLangOpts() const
Definition: Preprocessor.h:1061
Preprocessor.h
length
float __ovld __cnfn length(float)
Return the length of vector p, i.e., sqrt(p.x2 + p.y 2 + ...)
clang::Token::getKind
tok::TokenKind getKind() const
Definition: Token.h:93
clang::TokenConcatenation::TokenConcatenation
TokenConcatenation(const Preprocessor &PP)
Definition: TokenConcatenation.cpp:69
clang::Token::is
bool is(tok::TokenKind K) const
is/isNot - Predicates to check if this token is a specific kind, as in "if (Tok.is(tok::l_brace)) {....
Definition: Token.h:98
clang::Token::needsCleaning
bool needsCleaning() const
Return true if this token has trigraphs or escaped newlines in it.
Definition: Token.h:287
clang::Token::isNot
bool isNot(tok::TokenKind K) const
Definition: Token.h:99
clang::Token::isLiteral
bool isLiteral() const
Return true if this is a "literal", like a numeric constant, string, etc.
Definition: Token.h:115
clang::Token::getLength
unsigned getLength() const
Definition: Token.h:129
clang::Preprocessor::getSourceManager
SourceManager & getSourceManager() const
Definition: Preprocessor.h:1065
clang::Preprocessor::getSpelling
StringRef getSpelling(SourceLocation loc, SmallVectorImpl< char > &buffer, bool *invalid=nullptr) const
Return the 'spelling' of the token at the given location; does not go up to the spelling location or ...
Definition: Preprocessor.h:1913
clang::tok::TokenKind
TokenKind
Provides a simple uniform namespace for tokens from all C languages.
Definition: TokenKinds.h:25
CharInfo.h
clang::IdentifierInfo
One of these records is kept for each identifier that is lexed.
Definition: IdentifierTable.h:85
clang::Token::getLocation
SourceLocation getLocation() const
Return a source location identifier for the specified offset in the current file.
Definition: Token.h:126
clang::LangOptions
Keeps track of the various options that can be enabled, which controls the dialect of C or C++ that i...
Definition: LangOptions.h:81
clang::Token::isAnnotation
bool isAnnotation() const
Return true if this is any of tok::annot_* kind tokens.
Definition: Token.h:120
clang::TokenConcatenation::AvoidConcat
bool AvoidConcat(const Token &PrevPrevTok, const Token &PrevTok, const Token &Tok) const
AvoidConcat - If printing PrevTok immediately followed by Tok would cause the two individual tokens t...
Definition: TokenConcatenation.cpp:160
clang
Definition: CalledOnceCheck.h:17
memset
__DEVICE__ void * memset(void *__a, int __b, size_t __c)
Definition: __clang_cuda_device_functions.h:1552
clang::isDigit
LLVM_READONLY bool isDigit(unsigned char c)
Return true if this character is an ASCII digit: [0-9].
Definition: CharInfo.h:99
clang::Token::isOneOf
bool isOneOf(tok::TokenKind K1, tok::TokenKind K2) const
Definition: Token.h:100
clang::CPlusPlus11
@ CPlusPlus11
Definition: LangStandard.h:54
clang::Preprocessor
Engages in a tight little dance with the lexer to efficiently preprocess tokens.
Definition: Preprocessor.h:129
SM
#define SM(sm)
Definition: Cuda.cpp:79
clang::Token::hasUDSuffix
bool hasUDSuffix() const
Return true if this token is a string or character literal which has a ud-suffix.
Definition: Token.h:295
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