clang  9.0.0svn
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 
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;
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 
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 {
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.
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 }
SourceLocation getLocWithOffset(int Offset) const
Return a source location with the specified offset from this SourceLocation.
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:94
const char * getCharacterData(SourceLocation SL, bool *Invalid=nullptr) const
Return a pointer to the start of the specified location in the appropriate spelling MemoryBuffer...
TokenConcatenation(const Preprocessor &PP)
bool isAnnotation() const
Return true if this is any of tok::annot_* kind tokens.
Definition: Token.h:117
tok::TokenKind getKind() const
Definition: Token.h:89
bool isLiteral() const
Return true if this is a "literal", like a numeric constant, string, etc.
Definition: Token.h:112
One of these records is kept for each identifier that is lexed.
Token - This structure provides full information about a lexed token.
Definition: Token.h:34
Keeps track of the various options that can be enabled, which controls the dialect of C or C++ that i...
Definition: LangOptions.h:49
const LangOptions & getLangOpts() const
Definition: Preprocessor.h:814
StringRef getSpelling(SourceLocation loc, SmallVectorImpl< char > &buffer, bool *invalid=nullptr) const
Return the &#39;spelling&#39; of the token at the given location; does not go up to the spelling location or ...
bool hasUDSuffix() const
Return true if this token is a string or character literal which has a ud-suffix. ...
Definition: Token.h:290
const FormatToken & Tok
SourceLocation getSpellingLoc(SourceLocation Loc) const
Given a SourceLocation object, return the spelling location referenced by the ID. ...
__DEVICE__ void * memset(void *__a, int __b, size_t __c)
SourceLocation getLocation() const
Return a source location identifier for the specified offset in the current file. ...
Definition: Token.h:123
Defines the clang::Preprocessor interface.
float __ovld __cnfn length(float p)
Return the length of vector p, i.e., sqrt(p.x2 + p.y 2 + ...)
const SourceManager & SM
Definition: Format.cpp:1535
SourceManager & getSourceManager() const
Definition: Preprocessor.h:818
Encodes a location in the source.
IdentifierInfo * getIdentifierInfo() const
Definition: Token.h:176
TokenKind
Provides a simple uniform namespace for tokens from all C languages.
Definition: TokenKinds.h:24
bool isNot(tok::TokenKind K) const
Definition: Token.h:95
Dataflow Directional Tag Classes.
static char GetFirstChar(const Preprocessor &PP, const Token &Tok)
GetFirstChar - Get the first character of the token.
bool isOneOf(tok::TokenKind K1, tok::TokenKind K2) const
Definition: Token.h:96
unsigned getLength() const
Definition: Token.h:126
const char * getLiteralData() const
getLiteralData - For a literal token (numeric constant, string, etc), this returns a pointer to the s...
Definition: Token.h:214
LLVM_READONLY bool isDigit(unsigned char c)
Return true if this character is an ASCII digit: [0-9].
Definition: CharInfo.h:93
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...
static bool IsStringPrefix(StringRef Str, bool CPlusPlus11)
IsStringPrefix - Return true if Str is a string prefix.
bool needsCleaning() const
Return true if this token has trigraphs or escaped newlines in it.
Definition: Token.h:282
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:147
This class handles loading and caching of source files into memory.
Engages in a tight little dance with the lexer to efficiently preprocess tokens.
Definition: Preprocessor.h:123