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//===--- RewriteMacros.cpp - Rewrite macros into their expansions ---------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This code rewrites macro invocations into their expansions. This gives you
// a macro expanded file that retains comments and #includes.
//
//===----------------------------------------------------------------------===//
#include "clang/Rewrite/Frontend/Rewriters.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Rewrite/Core/Rewriter.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/raw_ostream.h"
#include <cstdio>
#include <memory>
using namespace clang;
/// isSameToken - Return true if the two specified tokens start have the same
/// content.
static bool isSameToken(Token &RawTok, Token &PPTok) {
// If two tokens have the same kind and the same identifier info, they are
// obviously the same.
if (PPTok.getKind() == RawTok.getKind() &&
PPTok.getIdentifierInfo() == RawTok.getIdentifierInfo())
return true;
// Otherwise, if they are different but have the same identifier info, they
// are also considered to be the same. This allows keywords and raw lexed
// identifiers with the same name to be treated the same.
if (PPTok.getIdentifierInfo() &&
PPTok.getIdentifierInfo() == RawTok.getIdentifierInfo())
return true;
return false;
}
/// GetNextRawTok - Return the next raw token in the stream, skipping over
/// comments if ReturnComment is false.
static const Token &GetNextRawTok(const std::vector<Token> &RawTokens,
unsigned &CurTok, bool ReturnComment) {
assert(CurTok < RawTokens.size() && "Overran eof!");
// If the client doesn't want comments and we have one, skip it.
if (!ReturnComment && RawTokens[CurTok].is(tok::comment))
++CurTok;
return RawTokens[CurTok++];
}
/// LexRawTokensFromMainFile - Lets all the raw tokens from the main file into
/// the specified vector.
static void LexRawTokensFromMainFile(Preprocessor &PP,
std::vector<Token> &RawTokens) {
SourceManager &SM = PP.getSourceManager();
// Create a lexer to lex all the tokens of the main file in raw mode. Even
// though it is in raw mode, it will not return comments.
llvm::MemoryBufferRef FromFile = SM.getBufferOrFake(SM.getMainFileID());
Lexer RawLex(SM.getMainFileID(), FromFile, SM, PP.getLangOpts());
// Switch on comment lexing because we really do want them.
RawLex.SetCommentRetentionState(true);
Token RawTok;
do {
RawLex.LexFromRawLexer(RawTok);
// If we have an identifier with no identifier info for our raw token, look
// up the identifier info. This is important for equality comparison of
// identifier tokens.
if (RawTok.is(tok::raw_identifier))
PP.LookUpIdentifierInfo(RawTok);
RawTokens.push_back(RawTok);
} while (RawTok.isNot(tok::eof));
}
/// RewriteMacrosInInput - Implement -rewrite-macros mode.
void clang::RewriteMacrosInInput(Preprocessor &PP, raw_ostream *OS) {
SourceManager &SM = PP.getSourceManager();
Rewriter Rewrite;
Rewrite.setSourceMgr(SM, PP.getLangOpts());
RewriteBuffer &RB = Rewrite.getEditBuffer(SM.getMainFileID());
std::vector<Token> RawTokens;
LexRawTokensFromMainFile(PP, RawTokens);
unsigned CurRawTok = 0;
Token RawTok = GetNextRawTok(RawTokens, CurRawTok, false);
// Get the first preprocessing token.
PP.EnterMainSourceFile();
Token PPTok;
PP.Lex(PPTok);
// Preprocess the input file in parallel with raw lexing the main file. Ignore
// all tokens that are preprocessed from a file other than the main file (e.g.
// a header). If we see tokens that are in the preprocessed file but not the
// lexed file, we have a macro expansion. If we see tokens in the lexed file
// that aren't in the preprocessed view, we have macros that expand to no
// tokens, or macro arguments etc.
while (RawTok.isNot(tok::eof) || PPTok.isNot(tok::eof)) {
SourceLocation PPLoc = SM.getExpansionLoc(PPTok.getLocation());
// If PPTok is from a different source file, ignore it.
if (!SM.isWrittenInMainFile(PPLoc)) {
PP.Lex(PPTok);
continue;
}
// If the raw file hits a preprocessor directive, they will be extra tokens
// in the raw file that don't exist in the preprocsesed file. However, we
// choose to preserve them in the output file and otherwise handle them
// specially.
if (RawTok.is(tok::hash) && RawTok.isAtStartOfLine()) {
// If this is a #warning directive or #pragma mark (GNU extensions),
// comment the line out.
if (RawTokens[CurRawTok].is(tok::identifier)) {
const IdentifierInfo *II = RawTokens[CurRawTok].getIdentifierInfo();
if (II->getName() == "warning") {
// Comment out #warning.
RB.InsertTextAfter(SM.getFileOffset(RawTok.getLocation()), "//");
} else if (II->getName() == "pragma" &&
RawTokens[CurRawTok+1].is(tok::identifier) &&
(RawTokens[CurRawTok+1].getIdentifierInfo()->getName() ==
"mark")) {
// Comment out #pragma mark.
RB.InsertTextAfter(SM.getFileOffset(RawTok.getLocation()), "//");
}
}
// Otherwise, if this is a #include or some other directive, just leave it
// in the file by skipping over the line.
RawTok = GetNextRawTok(RawTokens, CurRawTok, false);
while (!RawTok.isAtStartOfLine() && RawTok.isNot(tok::eof))
RawTok = GetNextRawTok(RawTokens, CurRawTok, false);
continue;
}
// Okay, both tokens are from the same file. Get their offsets from the
// start of the file.
unsigned PPOffs = SM.getFileOffset(PPLoc);
unsigned RawOffs = SM.getFileOffset(RawTok.getLocation());
// If the offsets are the same and the token kind is the same, ignore them.
if (PPOffs == RawOffs && isSameToken(RawTok, PPTok)) {
RawTok = GetNextRawTok(RawTokens, CurRawTok, false);
PP.Lex(PPTok);
continue;
}
// If the PP token is farther along than the raw token, something was
// deleted. Comment out the raw token.
if (RawOffs <= PPOffs) {
// Comment out a whole run of tokens instead of bracketing each one with
// comments. Add a leading space if RawTok didn't have one.
bool HasSpace = RawTok.hasLeadingSpace();
RB.InsertTextAfter(RawOffs, &" /*"[HasSpace]);
unsigned EndPos;
do {
EndPos = RawOffs+RawTok.getLength();
RawTok = GetNextRawTok(RawTokens, CurRawTok, true);
RawOffs = SM.getFileOffset(RawTok.getLocation());
if (RawTok.is(tok::comment)) {
// Skip past the comment.
RawTok = GetNextRawTok(RawTokens, CurRawTok, false);
break;
}
} while (RawOffs <= PPOffs && !RawTok.isAtStartOfLine() &&
(PPOffs != RawOffs || !isSameToken(RawTok, PPTok)));
RB.InsertTextBefore(EndPos, "*/");
continue;
}
// Otherwise, there was a replacement an expansion. Insert the new token
// in the output buffer. Insert the whole run of new tokens at once to get
// them in the right order.
unsigned InsertPos = PPOffs;
std::string Expansion;
while (PPOffs < RawOffs) {
Expansion += ' ' + PP.getSpelling(PPTok);
PP.Lex(PPTok);
PPLoc = SM.getExpansionLoc(PPTok.getLocation());
PPOffs = SM.getFileOffset(PPLoc);
}
Expansion += ' ';
RB.InsertTextBefore(InsertPos, Expansion);
}
// Get the buffer corresponding to MainFileID. If we haven't changed it, then
// we are done.
if (const RewriteBuffer *RewriteBuf =
Rewrite.getRewriteBufferFor(SM.getMainFileID())) {
//printf("Changed:\n");
*OS << std::string(RewriteBuf->begin(), RewriteBuf->end());
} else {
fprintf(stderr, "No changes\n");
}
OS->flush();
}
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