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
14#include "clang/Lex/TokenConcatenation.h"
15#include "clang/Basic/CharInfo.h"
16#include "clang/Lex/Preprocessor.h"
17#include "llvm/Support/ErrorHandling.h"
18using namespace clang;
19
20
21/// IsStringPrefix - Return true if Str is a string prefix.
22/// 'L', 'u', 'U', or 'u8'. Including raw versions.
23static 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.
48bool 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;
54    SourceManager &SM = PP.getSourceManager();
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
70TokenConcatenation::TokenConcatenation(Preprocessor &pp) : PP(pp) {
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.
125static 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 {
133      SourceManager &SM = PP.getSourceManager();
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 "...".
157bool 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.
163  SourceManager &SM = PP.getSourceManager();
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    // FALL THROUGH.
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}
288