| //===--- ScratchBuffer.cpp - Scratch space for forming tokens -------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file 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/SourceManager.h" |
| #include "llvm/Support/MemoryBuffer.h" |
| #include <cstring> |
| 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; |
| } |
| |
| /// getToken - Splat the specified text into a temporary MemoryBuffer 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, |
| const char *&DestPtr) { |
| if (BytesUsed+Len > ScratchBufSize) |
| AllocScratchBuffer(Len); |
| |
| // Return a pointer to the character data. |
| DestPtr = CurBuffer+BytesUsed; |
| |
| // Copy the token data into the buffer. |
| memcpy(CurBuffer+BytesUsed, Buf, Len); |
| |
| // Remember that we used these bytes. |
| BytesUsed += Len; |
| |
| return BufferStartLoc.getFileLocWithOffset(BytesUsed-Len); |
| } |
| |
| 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; |
| |
| llvm::MemoryBuffer *Buf = |
| llvm::MemoryBuffer::getNewMemBuffer(RequestLen, "<scratch space>"); |
| FileID FID = SourceMgr.createFileIDForMemBuffer(Buf); |
| BufferStartLoc = SourceMgr.getLocForStartOfFile(FID); |
| CurBuffer = const_cast<char*>(Buf->getBufferStart()); |
| BytesUsed = 0; |
| } |