1 //===--- TokenConcatenation.cpp - Token Concatenation Avoidance -----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the TokenConcatenation class.
12 //===----------------------------------------------------------------------===//
14 #include "clang/Lex/TokenConcatenation.h"
15 #include "clang/Lex/Preprocessor.h"
16 #include "llvm/Support/ErrorHandling.h"
17 using namespace clang;
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 CPlusPlus0x) {
25 (CPlusPlus0x && (Str[0] == 'u' || Str[0] == 'U' || Str[0] == 'R'))) {
28 return true; // "L", "u", "U", and "R"
30 // Check for raw flavors. Need to make sure the first character wasn't
31 // already R. Need CPlusPlus0x check for "LR".
32 if (Str[1] == 'R' && Str[0] != 'R' && Str.size() == 2 && CPlusPlus0x)
33 return true; // "LR", "uR", "UR"
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"
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.getLangOptions();
50 if (!Tok.needsCleaning()) {
51 if (Tok.getLength() < 1 || Tok.getLength() > 3)
53 SourceManager &SM = PP.getSourceManager();
54 const char *Ptr = SM.getCharacterData(SM.getSpellingLoc(Tok.getLocation()));
55 return IsStringPrefix(StringRef(Ptr, Tok.getLength()),
56 LangOpts.CPlusPlus0x);
59 if (Tok.getLength() < 256) {
61 const char *TokPtr = Buffer;
62 unsigned length = PP.getSpelling(Tok, TokPtr);
63 return IsStringPrefix(StringRef(TokPtr, length), LangOpts.CPlusPlus0x);
66 return IsStringPrefix(StringRef(PP.getSpelling(Tok)), LangOpts.CPlusPlus0x);
69 TokenConcatenation::TokenConcatenation(Preprocessor &pp) : PP(pp) {
70 memset(TokenInfo, 0, sizeof(TokenInfo));
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;
88 // These tokens change behavior if followed by an '='.
89 TokenInfo[tok::amp ] |= aci_avoid_equal; // &=
90 TokenInfo[tok::plus ] |= aci_avoid_equal; // +=
91 TokenInfo[tok::minus ] |= aci_avoid_equal; // -=
92 TokenInfo[tok::slash ] |= aci_avoid_equal; // /=
93 TokenInfo[tok::less ] |= aci_avoid_equal; // <=
94 TokenInfo[tok::greater ] |= aci_avoid_equal; // >=
95 TokenInfo[tok::pipe ] |= aci_avoid_equal; // |=
96 TokenInfo[tok::percent ] |= aci_avoid_equal; // %=
97 TokenInfo[tok::star ] |= aci_avoid_equal; // *=
98 TokenInfo[tok::exclaim ] |= aci_avoid_equal; // !=
99 TokenInfo[tok::lessless ] |= aci_avoid_equal; // <<=
100 TokenInfo[tok::greatergreater] |= aci_avoid_equal; // >>=
101 TokenInfo[tok::caret ] |= aci_avoid_equal; // ^=
102 TokenInfo[tok::equal ] |= aci_avoid_equal; // ==
105 /// GetFirstChar - Get the first character of the token \arg Tok,
106 /// avoiding calls to getSpelling where possible.
107 static char GetFirstChar(Preprocessor &PP, const Token &Tok) {
108 if (IdentifierInfo *II = Tok.getIdentifierInfo()) {
109 // Avoid spelling identifiers, the most common form of token.
110 return II->getNameStart()[0];
111 } else if (!Tok.needsCleaning()) {
112 if (Tok.isLiteral() && Tok.getLiteralData()) {
113 return *Tok.getLiteralData();
115 SourceManager &SM = PP.getSourceManager();
116 return *SM.getCharacterData(SM.getSpellingLoc(Tok.getLocation()));
118 } else if (Tok.getLength() < 256) {
120 const char *TokPtr = Buffer;
121 PP.getSpelling(Tok, TokPtr);
124 return PP.getSpelling(Tok)[0];
128 /// AvoidConcat - If printing PrevTok immediately followed by Tok would cause
129 /// the two individual tokens to be lexed as a single token, return true
130 /// (which causes a space to be printed between them). This allows the output
131 /// of -E mode to be lexed to the same token stream as lexing the input
134 /// This code must conservatively return true if it doesn't want to be 100%
135 /// accurate. This will cause the output to include extra space characters,
136 /// but the resulting output won't have incorrect concatenations going on.
137 /// Examples include "..", which we print with a space between, because we
138 /// don't want to track enough to tell "x.." from "...".
139 bool TokenConcatenation::AvoidConcat(const Token &PrevPrevTok,
140 const Token &PrevTok,
141 const Token &Tok) const {
142 // First, check to see if the tokens were directly adjacent in the original
143 // source. If they were, it must be okay to stick them together: if there
144 // were an issue, the tokens would have been lexed differently.
145 if (PrevTok.getLocation().isFileID() && Tok.getLocation().isFileID() &&
146 PrevTok.getLocation().getLocWithOffset(PrevTok.getLength()) ==
150 tok::TokenKind PrevKind = PrevTok.getKind();
151 if (PrevTok.getIdentifierInfo()) // Language keyword or named operator.
152 PrevKind = tok::identifier;
154 // Look up information on when we should avoid concatenation with prevtok.
155 unsigned ConcatInfo = TokenInfo[PrevKind];
157 // If prevtok never causes a problem for anything after it, return quickly.
158 if (ConcatInfo == 0) return false;
160 if (ConcatInfo & aci_avoid_equal) {
161 // If the next token is '=' or '==', avoid concatenation.
162 if (Tok.is(tok::equal) || Tok.is(tok::equalequal))
164 ConcatInfo &= ~aci_avoid_equal;
167 if (ConcatInfo == 0) return false;
169 // Basic algorithm: we look at the first character of the second token, and
170 // determine whether it, if appended to the first token, would form (or
171 // would contribute) to a larger token if concatenated.
173 if (ConcatInfo & aci_custom) {
174 // If the token does not need to know the first character, don't get it.
176 FirstChar = GetFirstChar(PP, Tok);
181 llvm_unreachable("InitAvoidConcatTokenInfo built wrong");
184 case tok::raw_identifier:
185 llvm_unreachable("tok::raw_identifier in non-raw lexing mode!");
188 case tok::identifier: // id+id or id+number or id+L"foo".
189 // id+'.'... will not append.
190 if (Tok.is(tok::numeric_constant))
191 return GetFirstChar(PP, Tok) != '.';
193 if (Tok.getIdentifierInfo() || Tok.is(tok::wide_string_literal) ||
194 Tok.is(tok::utf8_string_literal) || Tok.is(tok::utf16_string_literal) ||
195 Tok.is(tok::utf32_string_literal) || Tok.is(tok::wide_char_constant) ||
196 Tok.is(tok::utf16_char_constant) || Tok.is(tok::utf32_char_constant))
199 // If this isn't identifier + string, we're done.
200 if (Tok.isNot(tok::char_constant) && Tok.isNot(tok::string_literal))
203 // Otherwise, this is a narrow character or string. If the *identifier*
204 // is a literal 'L', 'u8', 'u' or 'U', avoid pasting L "foo" -> L"foo".
205 return IsIdentifierStringPrefix(PrevTok);
206 case tok::numeric_constant:
207 return isalnum(FirstChar) || Tok.is(tok::numeric_constant) ||
208 FirstChar == '+' || FirstChar == '-' || FirstChar == '.';
209 case tok::period: // ..., .*, .1234
210 return (FirstChar == '.' && PrevPrevTok.is(tok::period)) ||
211 isdigit(FirstChar) ||
212 (PP.getLangOptions().CPlusPlus && FirstChar == '*');
214 return FirstChar == '&';
215 case tok::plus: // ++
216 return FirstChar == '+';
217 case tok::minus: // --, ->, ->*
218 return FirstChar == '-' || FirstChar == '>';
219 case tok::slash: //, /*, //
220 return FirstChar == '*' || FirstChar == '/';
221 case tok::less: // <<, <<=, <:, <%
222 return FirstChar == '<' || FirstChar == ':' || FirstChar == '%';
223 case tok::greater: // >>, >>=
224 return FirstChar == '>';
225 case tok::pipe: // ||
226 return FirstChar == '|';
227 case tok::percent: // %>, %:
228 return FirstChar == '>' || FirstChar == ':';
229 case tok::colon: // ::, :>
230 return FirstChar == '>' ||
231 (PP.getLangOptions().CPlusPlus && FirstChar == ':');
232 case tok::hash: // ##, #@, %:%:
233 return FirstChar == '#' || FirstChar == '@' || FirstChar == '%';
234 case tok::arrow: // ->*
235 return PP.getLangOptions().CPlusPlus && FirstChar == '*';