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//===--- ScratchBuffer.cpp - Scratch space for forming tokens -------------===//
//
// 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 implements the ScratchBuffer interface.
//
//===----------------------------------------------------------------------===//
#include "clang/Lex/ScratchBuffer.h"
#include "clang/Basic/SourceBuffer.h"
#include "clang/Basic/SourceManager.h"
using namespace llvm;
using namespace clang;
// ScratchBufSize - The size of each chunk of scratch memory. Slightly less
//than a page, almost certainly enough for anything. :)
static const unsigned ScratchBufSize = 4060;
ScratchBuffer::ScratchBuffer(SourceManager &SM) : SourceMgr(SM), CurBuffer(0) {
// Set BytesUsed so that the first call to getToken will require an alloc.
BytesUsed = ScratchBufSize;
FileID = 0;
}
/// getToken - Splat the specified text into a temporary SourceBuffer and
/// return a SourceLocation that refers to the token. This is just like the
/// method below, but returns a location that indicates the physloc of the
/// token.
SourceLocation ScratchBuffer::getToken(const char *Buf, unsigned Len) {
if (BytesUsed+Len > ScratchBufSize)
AllocScratchBuffer(Len);
// Copy the token data into the buffer.
memcpy(CurBuffer+BytesUsed, Buf, Len);
// Remember that we used these bytes.
BytesUsed += Len;
assert(BytesUsed-Len < (1 << SourceLocation::FilePosBits) &&
"Out of range file position!");
return SourceLocation(FileID, BytesUsed-Len);
}
/// getToken - Splat the specified text into a temporary SourceBuffer and
/// return a SourceLocation that refers to the token. The SourceLoc value
/// gives a virtual location that the token will appear to be from.
SourceLocation ScratchBuffer::getToken(const char *Buf, unsigned Len,
SourceLocation SourceLoc) {
SourceLocation PhysLoc = getToken(Buf, Len);
// Map the physloc to the specified sourceloc.
unsigned InstantiationFileID =
SourceMgr.createFileIDForMacroExp(SourceLoc, PhysLoc.getFileID());
return SourceLocation(InstantiationFileID, PhysLoc.getRawFilePos());
}
void ScratchBuffer::AllocScratchBuffer(unsigned RequestLen) {
// Only pay attention to the requested length if it is larger than our default
// page size. If it is, we allocate an entire chunk for it. This is to
// support gigantic tokens, which almost certainly won't happen. :)
if (RequestLen < ScratchBufSize)
RequestLen = ScratchBufSize;
SourceBuffer *Buf =
SourceBuffer::getNewMemBuffer(RequestLen, "<scratch space>");
FileID = SourceMgr.createFileIDForMemBuffer(Buf);
CurBuffer = const_cast<char*>(Buf->getBufferStart());
BytesUsed = 0;
}
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