clang 19.0.0git
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
16#include "llvm/Support/ErrorHandling.h"
17using namespace clang;
18
19
20/// IsStringPrefix - Return true if Str is a string prefix.
21/// 'L', 'u', 'U', or 'u8'. Including raw versions.
22static 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.
47bool 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().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.
128static 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 "...".
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.
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, tok::annot_embed) &&
197 "unexpected annotation in AvoidConcat");
198
199 ConcatInfo = 0;
200 if (Tok.is(tok::annot_embed))
201 return true;
202 }
203
204 if (ConcatInfo == 0)
205 return false;
206
207 // Basic algorithm: we look at the first character of the second token, and
208 // determine whether it, if appended to the first token, would form (or
209 // would contribute) to a larger token if concatenated.
210 char FirstChar = 0;
211 if (ConcatInfo & aci_custom) {
212 // If the token does not need to know the first character, don't get it.
213 } else {
214 FirstChar = GetFirstChar(PP, Tok);
215 }
216
217 switch (PrevKind) {
218 default:
219 llvm_unreachable("InitAvoidConcatTokenInfo built wrong");
220
221 case tok::raw_identifier:
222 llvm_unreachable("tok::raw_identifier in non-raw lexing mode!");
223
224 case tok::string_literal:
225 case tok::wide_string_literal:
226 case tok::utf8_string_literal:
227 case tok::utf16_string_literal:
228 case tok::utf32_string_literal:
229 case tok::char_constant:
230 case tok::wide_char_constant:
231 case tok::utf8_char_constant:
232 case tok::utf16_char_constant:
233 case tok::utf32_char_constant:
234 if (!PP.getLangOpts().CPlusPlus11)
235 return false;
236
237 // In C++11, a string or character literal followed by an identifier is a
238 // single token.
239 if (Tok.getIdentifierInfo())
240 return true;
241
242 // A ud-suffix is an identifier. If the previous token ends with one, treat
243 // it as an identifier.
244 if (!PrevTok.hasUDSuffix())
245 return false;
246 [[fallthrough]];
247 case tok::identifier: // id+id or id+number or id+L"foo".
248 // id+'.'... will not append.
249 if (Tok.is(tok::numeric_constant))
250 return GetFirstChar(PP, Tok) != '.';
251
252 if (Tok.getIdentifierInfo() ||
253 Tok.isOneOf(tok::wide_string_literal, tok::utf8_string_literal,
254 tok::utf16_string_literal, tok::utf32_string_literal,
255 tok::wide_char_constant, tok::utf8_char_constant,
256 tok::utf16_char_constant, tok::utf32_char_constant))
257 return true;
258
259 // If this isn't identifier + string, we're done.
260 if (Tok.isNot(tok::char_constant) && Tok.isNot(tok::string_literal))
261 return false;
262
263 // Otherwise, this is a narrow character or string. If the *identifier*
264 // is a literal 'L', 'u8', 'u' or 'U', avoid pasting L "foo" -> L"foo".
265 return IsIdentifierStringPrefix(PrevTok);
266
267 case tok::numeric_constant:
268 return isPreprocessingNumberBody(FirstChar) ||
269 FirstChar == '+' || FirstChar == '-';
270 case tok::period: // ..., .*, .1234
271 return (FirstChar == '.' && PrevPrevTok.is(tok::period)) ||
272 isDigit(FirstChar) ||
273 (PP.getLangOpts().CPlusPlus && FirstChar == '*');
274 case tok::amp: // &&
275 return FirstChar == '&';
276 case tok::plus: // ++
277 return FirstChar == '+';
278 case tok::minus: // --, ->, ->*
279 return FirstChar == '-' || FirstChar == '>';
280 case tok::slash: //, /*, //
281 return FirstChar == '*' || FirstChar == '/';
282 case tok::less: // <<, <<=, <:, <%
283 return FirstChar == '<' || FirstChar == ':' || FirstChar == '%';
284 case tok::greater: // >>, >>=
285 return FirstChar == '>';
286 case tok::pipe: // ||
287 return FirstChar == '|';
288 case tok::percent: // %>, %:
289 return FirstChar == '>' || FirstChar == ':';
290 case tok::colon: // ::, :>
291 return FirstChar == '>' ||
292 (PP.getLangOpts().CPlusPlus && FirstChar == ':');
293 case tok::hash: // ##, #@, %:%:
294 return FirstChar == '#' || FirstChar == '@' || FirstChar == '%';
295 case tok::arrow: // ->*
296 return PP.getLangOpts().CPlusPlus && FirstChar == '*';
297 case tok::lessequal: // <=> (C++2a)
298 return PP.getLangOpts().CPlusPlus20 && FirstChar == '>';
299 }
300}
#define SM(sm)
Definition: Cuda.cpp:83
Defines the clang::Preprocessor interface.
static char GetFirstChar(const Preprocessor &PP, const Token &Tok)
GetFirstChar - Get the first character of the token.
static bool IsStringPrefix(StringRef Str, bool CPlusPlus11)
IsStringPrefix - Return true if Str is a string prefix.
__DEVICE__ void * memset(void *__a, int __b, size_t __c)
One of these records is kept for each identifier that is lexed.
Keeps track of the various options that can be enabled, which controls the dialect of C or C++ that i...
Definition: LangOptions.h:461
Engages in a tight little dance with the lexer to efficiently preprocess tokens.
Definition: Preprocessor.h:137
SourceManager & getSourceManager() const
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 ...
const LangOptions & getLangOpts() const
Encodes a location in the source.
SourceLocation getLocWithOffset(IntTy Offset) const
Return a source location with the specified offset from this SourceLocation.
This class handles loading and caching of source files into memory.
TokenConcatenation(const Preprocessor &PP)
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...
Token - This structure provides full information about a lexed token.
Definition: Token.h:36
IdentifierInfo * getIdentifierInfo() const
Definition: Token.h:187
bool isLiteral() const
Return true if this is a "literal", like a numeric constant, string, etc.
Definition: Token.h:116
SourceLocation getLocation() const
Return a source location identifier for the specified offset in the current file.
Definition: Token.h:132
unsigned getLength() const
Definition: Token.h:135
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:99
tok::TokenKind getKind() const
Definition: Token.h:94
bool isOneOf(tok::TokenKind K1, tok::TokenKind K2) const
Definition: Token.h:101
bool isNot(tok::TokenKind K) const
Definition: Token.h:100
bool isAnnotation() const
Return true if this is any of tok::annot_* kind tokens.
Definition: Token.h:121
bool hasUDSuffix() const
Return true if this token is a string or character literal which has a ud-suffix.
Definition: Token.h:303
bool needsCleaning() const
Return true if this token has trigraphs or escaped newlines in it.
Definition: Token.h:295
const char * getLiteralData() const
getLiteralData - For a literal token (numeric constant, string, etc), this returns a pointer to the s...
Definition: Token.h:225
TokenKind
Provides a simple uniform namespace for tokens from all C languages.
Definition: TokenKinds.h:25
The JSON file list parser is used to communicate input to InstallAPI.
@ CPlusPlus11
Definition: LangStandard.h:57
LLVM_READONLY bool isDigit(unsigned char c)
Return true if this character is an ASCII digit: [0-9].
Definition: CharInfo.h:114
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:168
float __ovld __cnfn length(float)
Return the length of vector p, i.e., sqrt(p.x2 + p.y 2 + ...)