PTHEntry PTHWriter::LexTokens(Lexer& L) {
// Pad 0's so that we emit tokens to a 4-byte alignment.
// This speed up reading them back in.
Pad(Out, 4);
Offset TokenOff = (Offset) Out.tell();
// Keep track of matching '#if' ... '#endif'.
typedef std::vector<std::pair<Offset, unsigned> > PPCondTable;
PPCondTable PPCond;
std::vector<unsigned> PPStartCond;
bool ParsingPreprocessorDirective = false;
Token Tok;
do {
L.LexFromRawLexer(Tok);
NextToken:
if ((Tok.isAtStartOfLine() || Tok.is(tok::eof)) &&
ParsingPreprocessorDirective) {
// Insert an eod token into the token cache. It has the same
// position as the next token that is not on the same line as the
// preprocessor directive. Observe that we continue processing
// 'Tok' when we exit this branch.
Token Tmp = Tok;
Tmp.setKind(tok::eod);
Tmp.clearFlag(Token::StartOfLine);
Tmp.setIdentifierInfo(0);
EmitToken(Tmp);
ParsingPreprocessorDirective = false;
}
if (Tok.is(tok::raw_identifier)) {
PP.LookUpIdentifierInfo(Tok);
EmitToken(Tok);
continue;
}
if (Tok.is(tok::hash) && Tok.isAtStartOfLine()) {
// Special processing for #include. Store the '#' token and lex
// the next token.
assert(!ParsingPreprocessorDirective);
Offset HashOff = (Offset) Out.tell();
// Get the next token.
Token NextTok;
L.LexFromRawLexer(NextTok);
// If we see the start of line, then we had a null directive "#". In
// this case, discard both tokens.
if (NextTok.isAtStartOfLine())
goto NextToken;
// The token is the start of a directive. Emit it.
EmitToken(Tok);
Tok = NextTok;
// Did we see 'include'/'import'/'include_next'?
if (Tok.isNot(tok::raw_identifier)) {
EmitToken(Tok);
continue;
}
IdentifierInfo* II = PP.LookUpIdentifierInfo(Tok);
tok::PPKeywordKind K = II->getPPKeywordID();
ParsingPreprocessorDirective = true;
switch (K) {
case tok::pp_not_keyword:
// Invalid directives "#foo" can occur in #if 0 blocks etc, just pass
// them through.
default:
break;
case tok::pp_include:
case tok::pp_import:
case tok::pp_include_next: {
// Save the 'include' token.
EmitToken(Tok);
// Lex the next token as an include string.
L.setParsingPreprocessorDirective(true);
L.LexIncludeFilename(Tok);
L.setParsingPreprocessorDirective(false);
assert(!Tok.isAtStartOfLine());
if (Tok.is(tok::raw_identifier))
PP.LookUpIdentifierInfo(Tok);
break;
}
case tok::pp_if:
case tok::pp_ifdef:
case tok::pp_ifndef: {
// Add an entry for '#if' and friends. We initially set the target
// index to 0. This will get backpatched when we hit #endif.
PPStartCond.push_back(PPCond.size());
PPCond.push_back(std::make_pair(HashOff, 0U));
break;
}
case tok::pp_endif: {
// Add an entry for '#endif'. We set the target table index to itself.
// This will later be set to zero when emitting to the PTH file. We
// use 0 for uninitialized indices because that is easier to debug.
unsigned index = PPCond.size();
// Backpatch the opening '#if' entry.
assert(!PPStartCond.empty());
assert(PPCond.size() > PPStartCond.back());
assert(PPCond[PPStartCond.back()].second == 0);
PPCond[PPStartCond.back()].second = index;
PPStartCond.pop_back();
// Add the new entry to PPCond.
PPCond.push_back(std::make_pair(HashOff, index));
EmitToken(Tok);
// Some files have gibberish on the same line as '#endif'.
// Discard these tokens.
do
L.LexFromRawLexer(Tok);
while (Tok.isNot(tok::eof) && !Tok.isAtStartOfLine());
// We have the next token in hand.
// Don't immediately lex the next one.
goto NextToken;
}
case tok::pp_elif:
case tok::pp_else: {
// Add an entry for #elif or #else.
// This serves as both a closing and opening of a conditional block.
// This means that its entry will get backpatched later.
unsigned index = PPCond.size();
// Backpatch the previous '#if' entry.
assert(!PPStartCond.empty());
assert(PPCond.size() > PPStartCond.back());
assert(PPCond[PPStartCond.back()].second == 0);
PPCond[PPStartCond.back()].second = index;
PPStartCond.pop_back();
// Now add '#elif' as a new block opening.
PPCond.push_back(std::make_pair(HashOff, 0U));
PPStartCond.push_back(index);
break;
}
}
}
EmitToken(Tok);
}
while (Tok.isNot(tok::eof));
assert(PPStartCond.empty() && "Error: imblanced preprocessor conditionals.");
// Next write out PPCond.
Offset PPCondOff = (Offset) Out.tell();
// Write out the size of PPCond so that clients can identifer empty tables.
Emit32(PPCond.size());
for (unsigned i = 0, e = PPCond.size(); i!=e; ++i) {
Emit32(PPCond[i].first - TokenOff);
uint32_t x = PPCond[i].second;
assert(x != 0 && "PPCond entry not backpatched.");
// Emit zero for #endifs. This allows us to do checking when
// we read the PTH file back in.
Emit32(x == i ? 0 : x);
}
return PTHEntry(TokenOff, PPCondOff);
}
