clang-1/Rewrite/Rewriter.cpp

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//===--- Rewriter.cpp - Code rewriting interface --------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by Chris Lattner and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the Rewriter class, which is used for code
// transformations.
//
//===----------------------------------------------------------------------===//
#include "clang/Rewrite/Rewriter.h"
#include "clang/AST/Stmt.h"
#include "clang/Lex/Lexer.h"
#include "clang/Basic/SourceManager.h"
#include <sstream>
using namespace clang;
/// getMappedOffset - Given an offset into the original SourceBuffer that this
/// RewriteBuffer is based on, map it into the offset space of the
/// RewriteBuffer.
unsigned RewriteBuffer::getMappedOffset(unsigned OrigOffset,
bool AfterInserts) const {
unsigned ResultOffset = OrigOffset;
unsigned DeltaIdx = 0;
// Move past any deltas that are relevant.
// FIXME: binary search.
for (; DeltaIdx != Deltas.size() &&
Deltas[DeltaIdx].FileLoc < OrigOffset; ++DeltaIdx)
ResultOffset += Deltas[DeltaIdx].Delta;
if (AfterInserts && DeltaIdx != Deltas.size() &&
OrigOffset == Deltas[DeltaIdx].FileLoc)
ResultOffset += Deltas[DeltaIdx].Delta;
return ResultOffset;
}
/// AddDelta - When a change is made that shifts around the text buffer, this
/// method is used to record that info.
void RewriteBuffer::AddDelta(unsigned OrigOffset, int Change) {
assert(Change != 0 && "Not changing anything");
unsigned DeltaIdx = 0;
// Skip over any unrelated deltas.
for (; DeltaIdx != Deltas.size() &&
Deltas[DeltaIdx].FileLoc < OrigOffset; ++DeltaIdx)
;
// If there is no a delta for this offset, insert a new delta record.
if (DeltaIdx == Deltas.size() || OrigOffset != Deltas[DeltaIdx].FileLoc) {
// If this is a removal, check to see if this can be folded into
// a delta at the end of the deletion. For example, if we have:
// ABCXDEF (X inserted after C) and delete C, we want to end up with no
// delta because X basically replaced C.
if (Change < 0 && DeltaIdx != Deltas.size() &&
OrigOffset-Change == Deltas[DeltaIdx].FileLoc) {
// Adjust the start of the delta to be the start of the deleted region.
Deltas[DeltaIdx].FileLoc += Change;
Deltas[DeltaIdx].Delta += Change;
// If the delta becomes a noop, remove it.
if (Deltas[DeltaIdx].Delta == 0)
Deltas.erase(Deltas.begin()+DeltaIdx);
return;
}
// Otherwise, create an entry and return.
Deltas.insert(Deltas.begin()+DeltaIdx,
SourceDelta::get(OrigOffset, Change));
return;
}
// Otherwise, we found a delta record at this offset, adjust it.
Deltas[DeltaIdx].Delta += Change;
// If it is now dead, remove it.
if (Deltas[DeltaIdx].Delta)
Deltas.erase(Deltas.begin()+DeltaIdx);
}
void RewriteBuffer::RemoveText(unsigned OrigOffset, unsigned Size) {
// Nothing to remove, exit early.
if (Size == 0) return;
unsigned RealOffset = getMappedOffset(OrigOffset, true);
assert(RealOffset+Size < Buffer.size() && "Invalid location");
// Remove the dead characters.
Buffer.erase(Buffer.begin()+RealOffset, Buffer.begin()+RealOffset+Size);
// Add a delta so that future changes are offset correctly.
AddDelta(OrigOffset, -Size);
}
void RewriteBuffer::InsertText(unsigned OrigOffset,
const char *StrData, unsigned StrLen) {
// Nothing to insert, exit early.
if (StrLen == 0) return;
unsigned RealOffset = getMappedOffset(OrigOffset, true);
assert(RealOffset <= Buffer.size() && "Invalid location");
// Remove the dead characters.
Buffer.insert(Buffer.begin()+RealOffset, StrData, StrData+StrLen);
// Add a delta so that future changes are offset correctly.
AddDelta(OrigOffset, StrLen);
}
/// ReplaceText - This method replaces a range of characters in the input
/// buffer with a new string. This is effectively a combined "remove/insert"
/// operation.
void RewriteBuffer::ReplaceText(unsigned OrigOffset, unsigned OrigLength,
const char *NewStr, unsigned NewLength) {
unsigned RealOffset = getMappedOffset(OrigOffset);
assert(RealOffset+OrigLength <= Buffer.size() && "Invalid location");
// Overwrite the common piece.
memcpy(&Buffer[RealOffset], NewStr, std::min(OrigLength, NewLength));
// If replacing without shifting around, just overwrite the text.
if (OrigLength == NewLength)
return;
// If inserting more than existed before, this is like an insertion.
if (NewLength > OrigLength) {
Buffer.insert(Buffer.begin()+RealOffset+OrigLength,
NewStr+OrigLength, NewStr+NewLength);
} else {
// If insertion less than existed before, this is like a removal.
Buffer.erase(Buffer.begin()+RealOffset+NewLength,
Buffer.begin()+RealOffset+OrigLength);
}
AddDelta(OrigOffset, NewLength-OrigLength);
}
//===----------------------------------------------------------------------===//
// Rewriter class
//===----------------------------------------------------------------------===//
/// getRangeSize - Return the size in bytes of the specified range if they
/// are in the same file. If not, this returns -1.
int Rewriter::getRangeSize(SourceRange Range) const {
if (!isRewritable(Range.getBegin()) ||
!isRewritable(Range.getEnd())) return -1;
unsigned StartOff, StartFileID;
unsigned EndOff , EndFileID;
StartOff = getLocationOffsetAndFileID(Range.getBegin(), StartFileID);
EndOff = getLocationOffsetAndFileID(Range.getEnd(), EndFileID);
if (StartFileID != EndFileID)
return -1;
// Adjust the end offset to the end of the last token, instead of being the
// start of the last token.
EndOff += Lexer::MeasureTokenLength(Range.getEnd(), *SourceMgr);
return EndOff-StartOff;
}
unsigned Rewriter::getLocationOffsetAndFileID(SourceLocation Loc,
unsigned &FileID) const {
std::pair<unsigned,unsigned> V = SourceMgr->getDecomposedFileLoc(Loc);
FileID = V.first;
return V.second;
}
/// getEditBuffer - Get or create a RewriteBuffer for the specified FileID.
///
RewriteBuffer &Rewriter::getEditBuffer(unsigned FileID) {
std::map<unsigned, RewriteBuffer>::iterator I =
RewriteBuffers.lower_bound(FileID);
if (I != RewriteBuffers.end() && I->first == FileID)
return I->second;
I = RewriteBuffers.insert(I, std::make_pair(FileID, RewriteBuffer()));
std::pair<const char*, const char*> MB = SourceMgr->getBufferData(FileID);
I->second.Initialize(MB.first, MB.second);
return I->second;
}
/// RemoveText - Remove the specified text region. This method is only valid
/// on a rewritable source location.
void Rewriter::RemoveText(SourceLocation Start, unsigned Length) {
unsigned FileID;
unsigned StartOffs = getLocationOffsetAndFileID(Start, FileID);
getEditBuffer(FileID).RemoveText(StartOffs, Length);
}
/// ReplaceText - This method replaces a range of characters in the input
/// buffer with a new string. This is effectively a combined "remove/insert"
/// operation.
void Rewriter::ReplaceText(SourceLocation Start, unsigned OrigLength,
const char *NewStr, unsigned NewLength) {
assert(isRewritable(Start) && "Not a rewritable location!");
unsigned StartFileID;
unsigned StartOffs = getLocationOffsetAndFileID(Start, StartFileID);
getEditBuffer(StartFileID).ReplaceText(StartOffs, OrigLength,
NewStr, NewLength);
}
/// ReplaceStmt - This replaces a Stmt/Expr with another, using the pretty
/// printer to generate the replacement code. This returns true if the input
/// could not be rewritten, or false if successful.
bool Rewriter::ReplaceStmt(Stmt *From, Stmt *To) {
// Measaure the old text.
int Size = getRangeSize(From->getSourceRange());
if (Size == -1)
return true;
// Get the new text.
std::ostringstream S;
To->printPretty(S);
const std::string &Str = S.str();
ReplaceText(From->getLocStart(), Size, &Str[0], Str.size());
return false;
}