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5a7971e0c3
Token now has a class of kinds for "literals", which include numeric constants, strings, etc. These tokens can optionally have a pointer to the start of the token in the lexer buffer. This makes it faster to get spelling and do other gymnastics, because we don't have to go through source locations. This change is performance neutral, but will make other changes more feasible down the road. llvm-svn: 63028
64 lines
2.3 KiB
C++
64 lines
2.3 KiB
C++
//===--- ScratchBuffer.cpp - Scratch space for forming tokens -------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the ScratchBuffer interface.
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//
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//===----------------------------------------------------------------------===//
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#include "clang/Lex/ScratchBuffer.h"
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#include "clang/Basic/SourceManager.h"
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#include "llvm/Support/MemoryBuffer.h"
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#include <cstring>
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using namespace clang;
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// ScratchBufSize - The size of each chunk of scratch memory. Slightly less
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//than a page, almost certainly enough for anything. :)
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static const unsigned ScratchBufSize = 4060;
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ScratchBuffer::ScratchBuffer(SourceManager &SM) : SourceMgr(SM), CurBuffer(0) {
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// Set BytesUsed so that the first call to getToken will require an alloc.
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BytesUsed = ScratchBufSize;
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}
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/// getToken - Splat the specified text into a temporary MemoryBuffer and
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/// return a SourceLocation that refers to the token. This is just like the
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/// method below, but returns a location that indicates the physloc of the
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/// token.
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SourceLocation ScratchBuffer::getToken(const char *Buf, unsigned Len,
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const char *&DestPtr) {
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if (BytesUsed+Len > ScratchBufSize)
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AllocScratchBuffer(Len);
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// Return a pointer to the character data.
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DestPtr = CurBuffer+BytesUsed;
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// Copy the token data into the buffer.
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memcpy(CurBuffer+BytesUsed, Buf, Len);
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// Remember that we used these bytes.
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BytesUsed += Len;
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return BufferStartLoc.getFileLocWithOffset(BytesUsed-Len);
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}
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void ScratchBuffer::AllocScratchBuffer(unsigned RequestLen) {
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// Only pay attention to the requested length if it is larger than our default
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// page size. If it is, we allocate an entire chunk for it. This is to
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// support gigantic tokens, which almost certainly won't happen. :)
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if (RequestLen < ScratchBufSize)
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RequestLen = ScratchBufSize;
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llvm::MemoryBuffer *Buf =
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llvm::MemoryBuffer::getNewMemBuffer(RequestLen, "<scratch space>");
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FileID FID = SourceMgr.createFileIDForMemBuffer(Buf);
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BufferStartLoc = SourceMgr.getLocForStartOfFile(FID);
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CurBuffer = const_cast<char*>(Buf->getBufferStart());
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BytesUsed = 0;
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}
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