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1 //===--- TokenLexer.cpp - Lex from a token stream -------------------------===//
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 TokenLexer interface.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "MacroArgs.h"
15 #include "clang/Lex/MacroInfo.h"
16 #include "clang/Lex/Preprocessor.h"
17 #include "clang/Lex/LexDiagnostic.h"
18 using namespace clang;
19 
20 /// MacroArgs ctor function - This destroys the vector passed in.
create(const MacroInfo * MI,const Token * UnexpArgTokens,unsigned NumToks,bool VarargsElided,Preprocessor & PP)21 MacroArgs *MacroArgs::create(const MacroInfo *MI,
22                              const Token *UnexpArgTokens,
23                              unsigned NumToks, bool VarargsElided,
24                              Preprocessor &PP) {
25   assert(MI->isFunctionLike() &&
26          "Can't have args for an object-like macro!");
27   MacroArgs **ResultEnt = 0;
28   unsigned ClosestMatch = ~0U;
29 
30   // See if we have an entry with a big enough argument list to reuse on the
31   // free list.  If so, reuse it.
32   for (MacroArgs **Entry = &PP.MacroArgCache; *Entry;
33        Entry = &(*Entry)->ArgCache)
34     if ((*Entry)->NumUnexpArgTokens >= NumToks &&
35         (*Entry)->NumUnexpArgTokens < ClosestMatch) {
36       ResultEnt = Entry;
37 
38       // If we have an exact match, use it.
39       if ((*Entry)->NumUnexpArgTokens == NumToks)
40         break;
41       // Otherwise, use the best fit.
42       ClosestMatch = (*Entry)->NumUnexpArgTokens;
43     }
44 
45   MacroArgs *Result;
46   if (ResultEnt == 0) {
47     // Allocate memory for a MacroArgs object with the lexer tokens at the end.
48     Result = (MacroArgs*)malloc(sizeof(MacroArgs) + NumToks*sizeof(Token));
49     // Construct the MacroArgs object.
50     new (Result) MacroArgs(NumToks, VarargsElided);
51   } else {
52     Result = *ResultEnt;
53     // Unlink this node from the preprocessors singly linked list.
54     *ResultEnt = Result->ArgCache;
55     Result->NumUnexpArgTokens = NumToks;
56     Result->VarargsElided = VarargsElided;
57   }
58 
59   // Copy the actual unexpanded tokens to immediately after the result ptr.
60   if (NumToks)
61     memcpy(const_cast<Token*>(Result->getUnexpArgument(0)),
62            UnexpArgTokens, NumToks*sizeof(Token));
63 
64   return Result;
65 }
66 
67 /// destroy - Destroy and deallocate the memory for this object.
68 ///
destroy(Preprocessor & PP)69 void MacroArgs::destroy(Preprocessor &PP) {
70   StringifiedArgs.clear();
71 
72   // Don't clear PreExpArgTokens, just clear the entries.  Clearing the entries
73   // would deallocate the element vectors.
74   for (unsigned i = 0, e = PreExpArgTokens.size(); i != e; ++i)
75     PreExpArgTokens[i].clear();
76 
77   // Add this to the preprocessor's free list.
78   ArgCache = PP.MacroArgCache;
79   PP.MacroArgCache = this;
80 }
81 
82 /// deallocate - This should only be called by the Preprocessor when managing
83 /// its freelist.
deallocate()84 MacroArgs *MacroArgs::deallocate() {
85   MacroArgs *Next = ArgCache;
86 
87   // Run the dtor to deallocate the vectors.
88   this->~MacroArgs();
89   // Release the memory for the object.
90   free(this);
91 
92   return Next;
93 }
94 
95 
96 /// getArgLength - Given a pointer to an expanded or unexpanded argument,
97 /// return the number of tokens, not counting the EOF, that make up the
98 /// argument.
getArgLength(const Token * ArgPtr)99 unsigned MacroArgs::getArgLength(const Token *ArgPtr) {
100   unsigned NumArgTokens = 0;
101   for (; ArgPtr->isNot(tok::eof); ++ArgPtr)
102     ++NumArgTokens;
103   return NumArgTokens;
104 }
105 
106 
107 /// getUnexpArgument - Return the unexpanded tokens for the specified formal.
108 ///
getUnexpArgument(unsigned Arg) const109 const Token *MacroArgs::getUnexpArgument(unsigned Arg) const {
110   // The unexpanded argument tokens start immediately after the MacroArgs object
111   // in memory.
112   const Token *Start = (const Token *)(this+1);
113   const Token *Result = Start;
114   // Scan to find Arg.
115   for (; Arg; ++Result) {
116     assert(Result < Start+NumUnexpArgTokens && "Invalid arg #");
117     if (Result->is(tok::eof))
118       --Arg;
119   }
120   assert(Result < Start+NumUnexpArgTokens && "Invalid arg #");
121   return Result;
122 }
123 
124 
125 /// ArgNeedsPreexpansion - If we can prove that the argument won't be affected
126 /// by pre-expansion, return false.  Otherwise, conservatively return true.
ArgNeedsPreexpansion(const Token * ArgTok,Preprocessor & PP) const127 bool MacroArgs::ArgNeedsPreexpansion(const Token *ArgTok,
128                                      Preprocessor &PP) const {
129   // If there are no identifiers in the argument list, or if the identifiers are
130   // known to not be macros, pre-expansion won't modify it.
131   for (; ArgTok->isNot(tok::eof); ++ArgTok)
132     if (IdentifierInfo *II = ArgTok->getIdentifierInfo()) {
133       if (II->hasMacroDefinition() && PP.getMacroInfo(II)->isEnabled())
134         // Return true even though the macro could be a function-like macro
135         // without a following '(' token.
136         return true;
137     }
138   return false;
139 }
140 
141 /// getPreExpArgument - Return the pre-expanded form of the specified
142 /// argument.
143 const std::vector<Token> &
getPreExpArgument(unsigned Arg,const MacroInfo * MI,Preprocessor & PP)144 MacroArgs::getPreExpArgument(unsigned Arg, const MacroInfo *MI,
145                              Preprocessor &PP) {
146   assert(Arg < MI->getNumArgs() && "Invalid argument number!");
147 
148   // If we have already computed this, return it.
149   if (PreExpArgTokens.size() < MI->getNumArgs())
150     PreExpArgTokens.resize(MI->getNumArgs());
151 
152   std::vector<Token> &Result = PreExpArgTokens[Arg];
153   if (!Result.empty()) return Result;
154 
155   const Token *AT = getUnexpArgument(Arg);
156   unsigned NumToks = getArgLength(AT)+1;  // Include the EOF.
157 
158   // Otherwise, we have to pre-expand this argument, populating Result.  To do
159   // this, we set up a fake TokenLexer to lex from the unexpanded argument
160   // list.  With this installed, we lex expanded tokens until we hit the EOF
161   // token at the end of the unexp list.
162   PP.EnterTokenStream(AT, NumToks, false /*disable expand*/,
163                       false /*owns tokens*/);
164 
165   // Lex all of the macro-expanded tokens into Result.
166   do {
167     Result.push_back(Token());
168     Token &Tok = Result.back();
169     PP.Lex(Tok);
170   } while (Result.back().isNot(tok::eof));
171 
172   // Pop the token stream off the top of the stack.  We know that the internal
173   // pointer inside of it is to the "end" of the token stream, but the stack
174   // will not otherwise be popped until the next token is lexed.  The problem is
175   // that the token may be lexed sometime after the vector of tokens itself is
176   // destroyed, which would be badness.
177   PP.RemoveTopOfLexerStack();
178   return Result;
179 }
180 
181 
182 /// StringifyArgument - Implement C99 6.10.3.2p2, converting a sequence of
183 /// tokens into the literal string token that should be produced by the C #
184 /// preprocessor operator.  If Charify is true, then it should be turned into
185 /// a character literal for the Microsoft charize (#@) extension.
186 ///
StringifyArgument(const Token * ArgToks,Preprocessor & PP,bool Charify,SourceLocation hashInstLoc)187 Token MacroArgs::StringifyArgument(const Token *ArgToks,
188                                    Preprocessor &PP, bool Charify,
189                                    SourceLocation hashInstLoc) {
190   Token Tok;
191   Tok.startToken();
192   Tok.setKind(Charify ? tok::char_constant : tok::string_literal);
193 
194   const Token *ArgTokStart = ArgToks;
195 
196   // Stringify all the tokens.
197   llvm::SmallString<128> Result;
198   Result += "\"";
199 
200   bool isFirst = true;
201   for (; ArgToks->isNot(tok::eof); ++ArgToks) {
202     const Token &Tok = *ArgToks;
203     if (!isFirst && (Tok.hasLeadingSpace() || Tok.isAtStartOfLine()))
204       Result += ' ';
205     isFirst = false;
206 
207     // If this is a string or character constant, escape the token as specified
208     // by 6.10.3.2p2.
209     if (Tok.is(tok::string_literal) ||       // "foo"
210         Tok.is(tok::wide_string_literal) ||  // L"foo"
211         Tok.is(tok::char_constant)) {        // 'x' and L'x'.
212       bool Invalid = false;
213       std::string TokStr = PP.getSpelling(Tok, &Invalid);
214       if (!Invalid) {
215         std::string Str = Lexer::Stringify(TokStr);
216         Result.append(Str.begin(), Str.end());
217       }
218     } else {
219       // Otherwise, just append the token.  Do some gymnastics to get the token
220       // in place and avoid copies where possible.
221       unsigned CurStrLen = Result.size();
222       Result.resize(CurStrLen+Tok.getLength());
223       const char *BufPtr = &Result[CurStrLen];
224       bool Invalid = false;
225       unsigned ActualTokLen = PP.getSpelling(Tok, BufPtr, &Invalid);
226 
227       if (!Invalid) {
228         // If getSpelling returned a pointer to an already uniqued version of
229         // the string instead of filling in BufPtr, memcpy it onto our string.
230         if (BufPtr != &Result[CurStrLen])
231           memcpy(&Result[CurStrLen], BufPtr, ActualTokLen);
232 
233         // If the token was dirty, the spelling may be shorter than the token.
234         if (ActualTokLen != Tok.getLength())
235           Result.resize(CurStrLen+ActualTokLen);
236       }
237     }
238   }
239 
240   // If the last character of the string is a \, and if it isn't escaped, this
241   // is an invalid string literal, diagnose it as specified in C99.
242   if (Result.back() == '\\') {
243     // Count the number of consequtive \ characters.  If even, then they are
244     // just escaped backslashes, otherwise it's an error.
245     unsigned FirstNonSlash = Result.size()-2;
246     // Guaranteed to find the starting " if nothing else.
247     while (Result[FirstNonSlash] == '\\')
248       --FirstNonSlash;
249     if ((Result.size()-1-FirstNonSlash) & 1) {
250       // Diagnose errors for things like: #define F(X) #X   /   F(\)
251       PP.Diag(ArgToks[-1], diag::pp_invalid_string_literal);
252       Result.pop_back();  // remove one of the \'s.
253     }
254   }
255   Result += '"';
256 
257   // If this is the charify operation and the result is not a legal character
258   // constant, diagnose it.
259   if (Charify) {
260     // First step, turn double quotes into single quotes:
261     Result[0] = '\'';
262     Result[Result.size()-1] = '\'';
263 
264     // Check for bogus character.
265     bool isBad = false;
266     if (Result.size() == 3)
267       isBad = Result[1] == '\'';   // ''' is not legal. '\' already fixed above.
268     else
269       isBad = (Result.size() != 4 || Result[1] != '\\');  // Not '\x'
270 
271     if (isBad) {
272       PP.Diag(ArgTokStart[0], diag::err_invalid_character_to_charify);
273       Result = "' '";  // Use something arbitrary, but legal.
274     }
275   }
276 
277   PP.CreateString(&Result[0], Result.size(), Tok, hashInstLoc);
278   return Tok;
279 }
280 
281 /// getStringifiedArgument - Compute, cache, and return the specified argument
282 /// that has been 'stringified' as required by the # operator.
getStringifiedArgument(unsigned ArgNo,Preprocessor & PP,SourceLocation hashInstLoc)283 const Token &MacroArgs::getStringifiedArgument(unsigned ArgNo,
284                                                Preprocessor &PP,
285                                                SourceLocation hashInstLoc) {
286   assert(ArgNo < NumUnexpArgTokens && "Invalid argument number!");
287   if (StringifiedArgs.empty()) {
288     StringifiedArgs.resize(getNumArguments());
289     memset((void*)&StringifiedArgs[0], 0,
290            sizeof(StringifiedArgs[0])*getNumArguments());
291   }
292   if (StringifiedArgs[ArgNo].isNot(tok::string_literal))
293     StringifiedArgs[ArgNo] = StringifyArgument(getUnexpArgument(ArgNo), PP,
294                                                /*Charify=*/false, hashInstLoc);
295   return StringifiedArgs[ArgNo];
296 }
297