1//===--- MacroArgs.cpp - Formal argument info for Macros ------------------===//
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 MacroArgs interface.
11//
12//===----------------------------------------------------------------------===//
13
14#include "clang/Lex/MacroArgs.h"
15#include "clang/Lex/LexDiagnostic.h"
16#include "clang/Lex/MacroInfo.h"
17#include "clang/Lex/Preprocessor.h"
18#include "llvm/ADT/SmallString.h"
19#include "llvm/Support/SaveAndRestore.h"
20#include <algorithm>
21
22using namespace clang;
23
24/// MacroArgs ctor function - This destroys the vector passed in.
25MacroArgs *MacroArgs::create(const MacroInfo *MI,
26                             ArrayRef<Token> UnexpArgTokens,
27                             bool VarargsElided, Preprocessor &PP) {
28  assert(MI->isFunctionLike() &&
29         "Can't have args for an object-like macro!");
30  MacroArgs **ResultEnt = nullptr;
31  unsigned ClosestMatch = ~0U;
32
33  // See if we have an entry with a big enough argument list to reuse on the
34  // free list.  If so, reuse it.
35  for (MacroArgs **Entry = &PP.MacroArgCache; *Entry;
36       Entry = &(*Entry)->ArgCache)
37    if ((*Entry)->NumUnexpArgTokens >= UnexpArgTokens.size() &&
38        (*Entry)->NumUnexpArgTokens < ClosestMatch) {
39      ResultEnt = Entry;
40
41      // If we have an exact match, use it.
42      if ((*Entry)->NumUnexpArgTokens == UnexpArgTokens.size())
43        break;
44      // Otherwise, use the best fit.
45      ClosestMatch = (*Entry)->NumUnexpArgTokens;
46    }
47
48  MacroArgs *Result;
49  if (!ResultEnt) {
50    // Allocate memory for a MacroArgs object with the lexer tokens at the end.
51    Result = (MacroArgs*)malloc(sizeof(MacroArgs) +
52                                UnexpArgTokens.size() * sizeof(Token));
53    // Construct the MacroArgs object.
54    new (Result) MacroArgs(UnexpArgTokens.size(), VarargsElided);
55  } else {
56    Result = *ResultEnt;
57    // Unlink this node from the preprocessors singly linked list.
58    *ResultEnt = Result->ArgCache;
59    Result->NumUnexpArgTokens = UnexpArgTokens.size();
60    Result->VarargsElided = VarargsElided;
61  }
62
63  // Copy the actual unexpanded tokens to immediately after the result ptr.
64  if (!UnexpArgTokens.empty())
65    std::copy(UnexpArgTokens.begin(), UnexpArgTokens.end(),
66              const_cast<Token*>(Result->getUnexpArgument(0)));
67
68  return Result;
69}
70
71/// destroy - Destroy and deallocate the memory for this object.
72///
73void MacroArgs::destroy(Preprocessor &PP) {
74  StringifiedArgs.clear();
75
76  // Don't clear PreExpArgTokens, just clear the entries.  Clearing the entries
77  // would deallocate the element vectors.
78  for (unsigned i = 0, e = PreExpArgTokens.size(); i != e; ++i)
79    PreExpArgTokens[i].clear();
80
81  // Add this to the preprocessor's free list.
82  ArgCache = PP.MacroArgCache;
83  PP.MacroArgCache = this;
84}
85
86/// deallocate - This should only be called by the Preprocessor when managing
87/// its freelist.
88MacroArgs *MacroArgs::deallocate() {
89  MacroArgs *Next = ArgCache;
90
91  // Run the dtor to deallocate the vectors.
92  this->~MacroArgs();
93  // Release the memory for the object.
94  free(this);
95
96  return Next;
97}
98
99
100/// getArgLength - Given a pointer to an expanded or unexpanded argument,
101/// return the number of tokens, not counting the EOF, that make up the
102/// argument.
103unsigned MacroArgs::getArgLength(const Token *ArgPtr) {
104  unsigned NumArgTokens = 0;
105  for (; ArgPtr->isNot(tok::eof); ++ArgPtr)
106    ++NumArgTokens;
107  return NumArgTokens;
108}
109
110
111/// getUnexpArgument - Return the unexpanded tokens for the specified formal.
112///
113const Token *MacroArgs::getUnexpArgument(unsigned Arg) const {
114  // The unexpanded argument tokens start immediately after the MacroArgs object
115  // in memory.
116  const Token *Start = (const Token *)(this+1);
117  const Token *Result = Start;
118  // Scan to find Arg.
119  for (; Arg; ++Result) {
120    assert(Result < Start+NumUnexpArgTokens && "Invalid arg #");
121    if (Result->is(tok::eof))
122      --Arg;
123  }
124  assert(Result < Start+NumUnexpArgTokens && "Invalid arg #");
125  return Result;
126}
127
128
129/// ArgNeedsPreexpansion - If we can prove that the argument won't be affected
130/// by pre-expansion, return false.  Otherwise, conservatively return true.
131bool MacroArgs::ArgNeedsPreexpansion(const Token *ArgTok,
132                                     Preprocessor &PP) const {
133  // If there are no identifiers in the argument list, or if the identifiers are
134  // known to not be macros, pre-expansion won't modify it.
135  for (; ArgTok->isNot(tok::eof); ++ArgTok)
136    if (IdentifierInfo *II = ArgTok->getIdentifierInfo()) {
137      if (II->hasMacroDefinition() && PP.getMacroInfo(II)->isEnabled())
138        // Return true even though the macro could be a function-like macro
139        // without a following '(' token.
140        return true;
141    }
142  return false;
143}
144
145/// getPreExpArgument - Return the pre-expanded form of the specified
146/// argument.
147const std::vector<Token> &
148MacroArgs::getPreExpArgument(unsigned Arg, const MacroInfo *MI,
149                             Preprocessor &PP) {
150  assert(Arg < MI->getNumArgs() && "Invalid argument number!");
151
152  // If we have already computed this, return it.
153  if (PreExpArgTokens.size() < MI->getNumArgs())
154    PreExpArgTokens.resize(MI->getNumArgs());
155
156  std::vector<Token> &Result = PreExpArgTokens[Arg];
157  if (!Result.empty()) return Result;
158
159  SaveAndRestore<bool> PreExpandingMacroArgs(PP.InMacroArgPreExpansion, true);
160
161  const Token *AT = getUnexpArgument(Arg);
162  unsigned NumToks = getArgLength(AT)+1;  // Include the EOF.
163
164  // Otherwise, we have to pre-expand this argument, populating Result.  To do
165  // this, we set up a fake TokenLexer to lex from the unexpanded argument
166  // list.  With this installed, we lex expanded tokens until we hit the EOF
167  // token at the end of the unexp list.
168  PP.EnterTokenStream(AT, NumToks, false /*disable expand*/,
169                      false /*owns tokens*/);
170
171  // Lex all of the macro-expanded tokens into Result.
172  do {
173    Result.push_back(Token());
174    Token &Tok = Result.back();
175    PP.Lex(Tok);
176  } while (Result.back().isNot(tok::eof));
177
178  // Pop the token stream off the top of the stack.  We know that the internal
179  // pointer inside of it is to the "end" of the token stream, but the stack
180  // will not otherwise be popped until the next token is lexed.  The problem is
181  // that the token may be lexed sometime after the vector of tokens itself is
182  // destroyed, which would be badness.
183  if (PP.InCachingLexMode())
184    PP.ExitCachingLexMode();
185  PP.RemoveTopOfLexerStack();
186  return Result;
187}
188
189
190/// StringifyArgument - Implement C99 6.10.3.2p2, converting a sequence of
191/// tokens into the literal string token that should be produced by the C #
192/// preprocessor operator.  If Charify is true, then it should be turned into
193/// a character literal for the Microsoft charize (#@) extension.
194///
195Token MacroArgs::StringifyArgument(const Token *ArgToks,
196                                   Preprocessor &PP, bool Charify,
197                                   SourceLocation ExpansionLocStart,
198                                   SourceLocation ExpansionLocEnd) {
199  Token Tok;
200  Tok.startToken();
201  Tok.setKind(Charify ? tok::char_constant : tok::string_literal);
202
203  const Token *ArgTokStart = ArgToks;
204
205  // Stringify all the tokens.
206  SmallString<128> Result;
207  Result += "\"";
208
209  bool isFirst = true;
210  for (; ArgToks->isNot(tok::eof); ++ArgToks) {
211    const Token &Tok = *ArgToks;
212    if (!isFirst && (Tok.hasLeadingSpace() || Tok.isAtStartOfLine()))
213      Result += ' ';
214    isFirst = false;
215
216    // If this is a string or character constant, escape the token as specified
217    // by 6.10.3.2p2.
218    if (tok::isStringLiteral(Tok.getKind()) || // "foo", u8R"x(foo)x"_bar, etc.
219        Tok.is(tok::char_constant) ||          // 'x'
220        Tok.is(tok::wide_char_constant) ||     // L'x'.
221        Tok.is(tok::utf16_char_constant) ||    // u'x'.
222        Tok.is(tok::utf32_char_constant)) {    // U'x'.
223      bool Invalid = false;
224      std::string TokStr = PP.getSpelling(Tok, &Invalid);
225      if (!Invalid) {
226        std::string Str = Lexer::Stringify(TokStr);
227        Result.append(Str.begin(), Str.end());
228      }
229    } else if (Tok.is(tok::code_completion)) {
230      PP.CodeCompleteNaturalLanguage();
231    } else {
232      // Otherwise, just append the token.  Do some gymnastics to get the token
233      // in place and avoid copies where possible.
234      unsigned CurStrLen = Result.size();
235      Result.resize(CurStrLen+Tok.getLength());
236      const char *BufPtr = &Result[CurStrLen];
237      bool Invalid = false;
238      unsigned ActualTokLen = PP.getSpelling(Tok, BufPtr, &Invalid);
239
240      if (!Invalid) {
241        // If getSpelling returned a pointer to an already uniqued version of
242        // the string instead of filling in BufPtr, memcpy it onto our string.
243        if (BufPtr != &Result[CurStrLen])
244          memcpy(&Result[CurStrLen], BufPtr, ActualTokLen);
245
246        // If the token was dirty, the spelling may be shorter than the token.
247        if (ActualTokLen != Tok.getLength())
248          Result.resize(CurStrLen+ActualTokLen);
249      }
250    }
251  }
252
253  // If the last character of the string is a \, and if it isn't escaped, this
254  // is an invalid string literal, diagnose it as specified in C99.
255  if (Result.back() == '\\') {
256    // Count the number of consequtive \ characters.  If even, then they are
257    // just escaped backslashes, otherwise it's an error.
258    unsigned FirstNonSlash = Result.size()-2;
259    // Guaranteed to find the starting " if nothing else.
260    while (Result[FirstNonSlash] == '\\')
261      --FirstNonSlash;
262    if ((Result.size()-1-FirstNonSlash) & 1) {
263      // Diagnose errors for things like: #define F(X) #X   /   F(\)
264      PP.Diag(ArgToks[-1], diag::pp_invalid_string_literal);
265      Result.pop_back();  // remove one of the \'s.
266    }
267  }
268  Result += '"';
269
270  // If this is the charify operation and the result is not a legal character
271  // constant, diagnose it.
272  if (Charify) {
273    // First step, turn double quotes into single quotes:
274    Result[0] = '\'';
275    Result[Result.size()-1] = '\'';
276
277    // Check for bogus character.
278    bool isBad = false;
279    if (Result.size() == 3)
280      isBad = Result[1] == '\'';   // ''' is not legal. '\' already fixed above.
281    else
282      isBad = (Result.size() != 4 || Result[1] != '\\');  // Not '\x'
283
284    if (isBad) {
285      PP.Diag(ArgTokStart[0], diag::err_invalid_character_to_charify);
286      Result = "' '";  // Use something arbitrary, but legal.
287    }
288  }
289
290  PP.CreateString(Result, Tok,
291                  ExpansionLocStart, ExpansionLocEnd);
292  return Tok;
293}
294
295/// getStringifiedArgument - Compute, cache, and return the specified argument
296/// that has been 'stringified' as required by the # operator.
297const Token &MacroArgs::getStringifiedArgument(unsigned ArgNo,
298                                               Preprocessor &PP,
299                                               SourceLocation ExpansionLocStart,
300                                               SourceLocation ExpansionLocEnd) {
301  assert(ArgNo < NumUnexpArgTokens && "Invalid argument number!");
302  if (StringifiedArgs.empty()) {
303    StringifiedArgs.resize(getNumArguments());
304    memset((void*)&StringifiedArgs[0], 0,
305           sizeof(StringifiedArgs[0])*getNumArguments());
306  }
307  if (StringifiedArgs[ArgNo].isNot(tok::string_literal))
308    StringifiedArgs[ArgNo] = StringifyArgument(getUnexpArgument(ArgNo), PP,
309                                               /*Charify=*/false,
310                                               ExpansionLocStart,
311                                               ExpansionLocEnd);
312  return StringifiedArgs[ArgNo];
313}
314