clang  6.0.0svn
TokenConcatenation.cpp
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1 //===--- TokenConcatenation.cpp - Token Concatenation Avoidance -----------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements the TokenConcatenation class.
11 //
12 //===----------------------------------------------------------------------===//
13 
15 #include "clang/Basic/CharInfo.h"
16 #include "clang/Lex/Preprocessor.h"
17 #include "llvm/Support/ErrorHandling.h"
18 using namespace clang;
19 
20 
21 /// IsStringPrefix - Return true if Str is a string prefix.
22 /// 'L', 'u', 'U', or 'u8'. Including raw versions.
23 static bool IsStringPrefix(StringRef Str, bool CPlusPlus11) {
24 
25  if (Str[0] == 'L' ||
26  (CPlusPlus11 && (Str[0] == 'u' || Str[0] == 'U' || Str[0] == 'R'))) {
27 
28  if (Str.size() == 1)
29  return true; // "L", "u", "U", and "R"
30 
31  // Check for raw flavors. Need to make sure the first character wasn't
32  // already R. Need CPlusPlus11 check for "LR".
33  if (Str[1] == 'R' && Str[0] != 'R' && Str.size() == 2 && CPlusPlus11)
34  return true; // "LR", "uR", "UR"
35 
36  // Check for "u8" and "u8R"
37  if (Str[0] == 'u' && Str[1] == '8') {
38  if (Str.size() == 2) return true; // "u8"
39  if (Str.size() == 3 && Str[2] == 'R') return true; // "u8R"
40  }
41  }
42 
43  return false;
44 }
45 
46 /// IsIdentifierStringPrefix - Return true if the spelling of the token
47 /// is literally 'L', 'u', 'U', or 'u8'. Including raw versions.
48 bool TokenConcatenation::IsIdentifierStringPrefix(const Token &Tok) const {
49  const LangOptions &LangOpts = PP.getLangOpts();
50 
51  if (!Tok.needsCleaning()) {
52  if (Tok.getLength() < 1 || Tok.getLength() > 3)
53  return false;
55  const char *Ptr = SM.getCharacterData(SM.getSpellingLoc(Tok.getLocation()));
56  return IsStringPrefix(StringRef(Ptr, Tok.getLength()),
57  LangOpts.CPlusPlus11);
58  }
59 
60  if (Tok.getLength() < 256) {
61  char Buffer[256];
62  const char *TokPtr = Buffer;
63  unsigned length = PP.getSpelling(Tok, TokPtr);
64  return IsStringPrefix(StringRef(TokPtr, length), LangOpts.CPlusPlus11);
65  }
66 
67  return IsStringPrefix(StringRef(PP.getSpelling(Tok)), LangOpts.CPlusPlus11);
68 }
69 
71  memset(TokenInfo, 0, sizeof(TokenInfo));
72 
73  // These tokens have custom code in AvoidConcat.
74  TokenInfo[tok::identifier ] |= aci_custom;
75  TokenInfo[tok::numeric_constant] |= aci_custom_firstchar;
76  TokenInfo[tok::period ] |= aci_custom_firstchar;
77  TokenInfo[tok::amp ] |= aci_custom_firstchar;
78  TokenInfo[tok::plus ] |= aci_custom_firstchar;
79  TokenInfo[tok::minus ] |= aci_custom_firstchar;
80  TokenInfo[tok::slash ] |= aci_custom_firstchar;
81  TokenInfo[tok::less ] |= aci_custom_firstchar;
82  TokenInfo[tok::greater ] |= aci_custom_firstchar;
83  TokenInfo[tok::pipe ] |= aci_custom_firstchar;
84  TokenInfo[tok::percent ] |= aci_custom_firstchar;
85  TokenInfo[tok::colon ] |= aci_custom_firstchar;
86  TokenInfo[tok::hash ] |= aci_custom_firstchar;
87  TokenInfo[tok::arrow ] |= aci_custom_firstchar;
88 
89  // These tokens have custom code in C++11 mode.
90  if (PP.getLangOpts().CPlusPlus11) {
91  TokenInfo[tok::string_literal ] |= aci_custom;
92  TokenInfo[tok::wide_string_literal ] |= aci_custom;
93  TokenInfo[tok::utf8_string_literal ] |= aci_custom;
94  TokenInfo[tok::utf16_string_literal] |= aci_custom;
95  TokenInfo[tok::utf32_string_literal] |= aci_custom;
96  TokenInfo[tok::char_constant ] |= aci_custom;
97  TokenInfo[tok::wide_char_constant ] |= aci_custom;
98  TokenInfo[tok::utf16_char_constant ] |= aci_custom;
99  TokenInfo[tok::utf32_char_constant ] |= aci_custom;
100  }
101 
102  // These tokens have custom code in C++1z mode.
103  if (PP.getLangOpts().CPlusPlus1z)
104  TokenInfo[tok::utf8_char_constant] |= aci_custom;
105 
106  // These tokens change behavior if followed by an '='.
107  TokenInfo[tok::amp ] |= aci_avoid_equal; // &=
108  TokenInfo[tok::plus ] |= aci_avoid_equal; // +=
109  TokenInfo[tok::minus ] |= aci_avoid_equal; // -=
110  TokenInfo[tok::slash ] |= aci_avoid_equal; // /=
111  TokenInfo[tok::less ] |= aci_avoid_equal; // <=
112  TokenInfo[tok::greater ] |= aci_avoid_equal; // >=
113  TokenInfo[tok::pipe ] |= aci_avoid_equal; // |=
114  TokenInfo[tok::percent ] |= aci_avoid_equal; // %=
115  TokenInfo[tok::star ] |= aci_avoid_equal; // *=
116  TokenInfo[tok::exclaim ] |= aci_avoid_equal; // !=
117  TokenInfo[tok::lessless ] |= aci_avoid_equal; // <<=
118  TokenInfo[tok::greatergreater] |= aci_avoid_equal; // >>=
119  TokenInfo[tok::caret ] |= aci_avoid_equal; // ^=
120  TokenInfo[tok::equal ] |= aci_avoid_equal; // ==
121 }
122 
123 /// GetFirstChar - Get the first character of the token \arg Tok,
124 /// avoiding calls to getSpelling where possible.
125 static char GetFirstChar(Preprocessor &PP, const Token &Tok) {
126  if (IdentifierInfo *II = Tok.getIdentifierInfo()) {
127  // Avoid spelling identifiers, the most common form of token.
128  return II->getNameStart()[0];
129  } else if (!Tok.needsCleaning()) {
130  if (Tok.isLiteral() && Tok.getLiteralData()) {
131  return *Tok.getLiteralData();
132  } else {
134  return *SM.getCharacterData(SM.getSpellingLoc(Tok.getLocation()));
135  }
136  } else if (Tok.getLength() < 256) {
137  char Buffer[256];
138  const char *TokPtr = Buffer;
139  PP.getSpelling(Tok, TokPtr);
140  return TokPtr[0];
141  } else {
142  return PP.getSpelling(Tok)[0];
143  }
144 }
145 
146 /// AvoidConcat - If printing PrevTok immediately followed by Tok would cause
147 /// the two individual tokens to be lexed as a single token, return true
148 /// (which causes a space to be printed between them). This allows the output
149 /// of -E mode to be lexed to the same token stream as lexing the input
150 /// directly would.
151 ///
152 /// This code must conservatively return true if it doesn't want to be 100%
153 /// accurate. This will cause the output to include extra space characters,
154 /// but the resulting output won't have incorrect concatenations going on.
155 /// Examples include "..", which we print with a space between, because we
156 /// don't want to track enough to tell "x.." from "...".
157 bool TokenConcatenation::AvoidConcat(const Token &PrevPrevTok,
158  const Token &PrevTok,
159  const Token &Tok) const {
160  // First, check to see if the tokens were directly adjacent in the original
161  // source. If they were, it must be okay to stick them together: if there
162  // were an issue, the tokens would have been lexed differently.
164  SourceLocation PrevSpellLoc = SM.getSpellingLoc(PrevTok.getLocation());
165  SourceLocation SpellLoc = SM.getSpellingLoc(Tok.getLocation());
166  if (PrevSpellLoc.getLocWithOffset(PrevTok.getLength()) == SpellLoc)
167  return false;
168 
169  tok::TokenKind PrevKind = PrevTok.getKind();
170  if (!PrevTok.isAnnotation() && PrevTok.getIdentifierInfo())
171  PrevKind = tok::identifier; // Language keyword or named operator.
172 
173  // Look up information on when we should avoid concatenation with prevtok.
174  unsigned ConcatInfo = TokenInfo[PrevKind];
175 
176  // If prevtok never causes a problem for anything after it, return quickly.
177  if (ConcatInfo == 0) return false;
178 
179  if (ConcatInfo & aci_avoid_equal) {
180  // If the next token is '=' or '==', avoid concatenation.
181  if (Tok.isOneOf(tok::equal, tok::equalequal))
182  return true;
183  ConcatInfo &= ~aci_avoid_equal;
184  }
185  if (Tok.isAnnotation()) {
186  // Modules annotation can show up when generated automatically for includes.
187  assert(Tok.isOneOf(tok::annot_module_include, tok::annot_module_begin,
188  tok::annot_module_end) &&
189  "unexpected annotation in AvoidConcat");
190  ConcatInfo = 0;
191  }
192 
193  if (ConcatInfo == 0)
194  return false;
195 
196  // Basic algorithm: we look at the first character of the second token, and
197  // determine whether it, if appended to the first token, would form (or
198  // would contribute) to a larger token if concatenated.
199  char FirstChar = 0;
200  if (ConcatInfo & aci_custom) {
201  // If the token does not need to know the first character, don't get it.
202  } else {
203  FirstChar = GetFirstChar(PP, Tok);
204  }
205 
206  switch (PrevKind) {
207  default:
208  llvm_unreachable("InitAvoidConcatTokenInfo built wrong");
209 
210  case tok::raw_identifier:
211  llvm_unreachable("tok::raw_identifier in non-raw lexing mode!");
212 
213  case tok::string_literal:
214  case tok::wide_string_literal:
215  case tok::utf8_string_literal:
216  case tok::utf16_string_literal:
217  case tok::utf32_string_literal:
218  case tok::char_constant:
219  case tok::wide_char_constant:
220  case tok::utf8_char_constant:
221  case tok::utf16_char_constant:
222  case tok::utf32_char_constant:
223  if (!PP.getLangOpts().CPlusPlus11)
224  return false;
225 
226  // In C++11, a string or character literal followed by an identifier is a
227  // single token.
228  if (Tok.getIdentifierInfo())
229  return true;
230 
231  // A ud-suffix is an identifier. If the previous token ends with one, treat
232  // it as an identifier.
233  if (!PrevTok.hasUDSuffix())
234  return false;
235  LLVM_FALLTHROUGH;
236  case tok::identifier: // id+id or id+number or id+L"foo".
237  // id+'.'... will not append.
238  if (Tok.is(tok::numeric_constant))
239  return GetFirstChar(PP, Tok) != '.';
240 
241  if (Tok.getIdentifierInfo() ||
242  Tok.isOneOf(tok::wide_string_literal, tok::utf8_string_literal,
243  tok::utf16_string_literal, tok::utf32_string_literal,
244  tok::wide_char_constant, tok::utf8_char_constant,
245  tok::utf16_char_constant, tok::utf32_char_constant))
246  return true;
247 
248  // If this isn't identifier + string, we're done.
249  if (Tok.isNot(tok::char_constant) && Tok.isNot(tok::string_literal))
250  return false;
251 
252  // Otherwise, this is a narrow character or string. If the *identifier*
253  // is a literal 'L', 'u8', 'u' or 'U', avoid pasting L "foo" -> L"foo".
254  return IsIdentifierStringPrefix(PrevTok);
255 
256  case tok::numeric_constant:
257  return isPreprocessingNumberBody(FirstChar) ||
258  FirstChar == '+' || FirstChar == '-';
259  case tok::period: // ..., .*, .1234
260  return (FirstChar == '.' && PrevPrevTok.is(tok::period)) ||
261  isDigit(FirstChar) ||
262  (PP.getLangOpts().CPlusPlus && FirstChar == '*');
263  case tok::amp: // &&
264  return FirstChar == '&';
265  case tok::plus: // ++
266  return FirstChar == '+';
267  case tok::minus: // --, ->, ->*
268  return FirstChar == '-' || FirstChar == '>';
269  case tok::slash: //, /*, //
270  return FirstChar == '*' || FirstChar == '/';
271  case tok::less: // <<, <<=, <:, <%
272  return FirstChar == '<' || FirstChar == ':' || FirstChar == '%';
273  case tok::greater: // >>, >>=
274  return FirstChar == '>';
275  case tok::pipe: // ||
276  return FirstChar == '|';
277  case tok::percent: // %>, %:
278  return FirstChar == '>' || FirstChar == ':';
279  case tok::colon: // ::, :>
280  return FirstChar == '>' ||
281  (PP.getLangOpts().CPlusPlus && FirstChar == ':');
282  case tok::hash: // ##, #@, %:%:
283  return FirstChar == '#' || FirstChar == '@' || FirstChar == '%';
284  case tok::arrow: // ->*
285  return PP.getLangOpts().CPlusPlus && FirstChar == '*';
286  }
287 }
static LLVM_READONLY bool isDigit(unsigned char c)
Return true if this character is an ASCII digit: [0-9].
Definition: CharInfo.h:94
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:95
const char * getCharacterData(SourceLocation SL, bool *Invalid=nullptr) const
Return a pointer to the start of the specified location in the appropriate spelling MemoryBuffer...
bool isAnnotation() const
Return true if this is any of tok::annot_* kind tokens.
Definition: Token.h:118
tok::TokenKind getKind() const
Definition: Token.h:90
bool isLiteral() const
Return true if this is a "literal", like a numeric constant, string, etc.
Definition: Token.h:113
static 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:148
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:35
Keeps track of the various options that can be enabled, which controls the dialect of C or C++ that i...
Definition: LangOptions.h:48
const LangOptions & getLangOpts() const
Definition: Preprocessor.h:728
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:291
const FormatToken & Tok
SourceLocation getSpellingLoc(SourceLocation Loc) const
Given a SourceLocation object, return the spelling location referenced by the ID. ...
SourceLocation getLocation() const
Return a source location identifier for the specified offset in the current file. ...
Definition: Token.h:124
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:1308
SourceManager & getSourceManager() const
Definition: Preprocessor.h:732
TokenConcatenation(Preprocessor &PP)
Encodes a location in the source.
IdentifierInfo * getIdentifierInfo() const
Definition: Token.h:177
TokenKind
Provides a simple uniform namespace for tokens from all C languages.
Definition: TokenKinds.h:25
bool isNot(tok::TokenKind K) const
Definition: Token.h:96
Dataflow Directional Tag Classes.
bool isOneOf(tok::TokenKind K1, tok::TokenKind K2) const
Definition: Token.h:97
unsigned getLength() const
Definition: Token.h:127
const char * getLiteralData() const
getLiteralData - For a literal token (numeric constant, string, etc), this returns a pointer to the s...
Definition: Token.h:215
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.
static char GetFirstChar(Preprocessor &PP, const Token &Tok)
GetFirstChar - Get the first character of the token.
bool needsCleaning() const
Return true if this token has trigraphs or escaped newlines in it.
Definition: Token.h:283
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:98