1 //===--- ScratchBuffer.cpp - Scratch space for forming tokens -------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file implements the ScratchBuffer interface. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "clang/Lex/ScratchBuffer.h" 15 #include "clang/Basic/SourceManager.h" 16 #include "llvm/Support/MemoryBuffer.h" 17 #include <cstring> 18 using namespace clang; 19 20 // ScratchBufSize - The size of each chunk of scratch memory. Slightly less 21 //than a page, almost certainly enough for anything. :) 22 static const unsigned ScratchBufSize = 4060; 23 24 ScratchBuffer::ScratchBuffer(SourceManager &SM) : SourceMgr(SM), CurBuffer(0) { 25 // Set BytesUsed so that the first call to getToken will require an alloc. 26 BytesUsed = ScratchBufSize; 27 } 28 29 /// getToken - Splat the specified text into a temporary MemoryBuffer and 30 /// return a SourceLocation that refers to the token. This is just like the 31 /// method below, but returns a location that indicates the physloc of the 32 /// token. 33 SourceLocation ScratchBuffer::getToken(const char *Buf, unsigned Len, 34 const char *&DestPtr) { 35 if (BytesUsed+Len+2 > ScratchBufSize) 36 AllocScratchBuffer(Len+2); 37 38 // Prefix the token with a \n, so that it looks like it is the first thing on 39 // its own virtual line in caret diagnostics. 40 CurBuffer[BytesUsed++] = '\n'; 41 42 // Return a pointer to the character data. 43 DestPtr = CurBuffer+BytesUsed; 44 45 // Copy the token data into the buffer. 46 memcpy(CurBuffer+BytesUsed, Buf, Len); 47 48 // Remember that we used these bytes. 49 BytesUsed += Len+1; 50 51 // Add a NUL terminator to the token. This keeps the tokens separated, in 52 // case they get relexed, and puts them on their own virtual lines in case a 53 // diagnostic points to one. 54 CurBuffer[BytesUsed-1] = '\0'; 55 56 return BufferStartLoc.getLocWithOffset(BytesUsed-Len-1); 57 } 58 59 void ScratchBuffer::AllocScratchBuffer(unsigned RequestLen) { 60 // Only pay attention to the requested length if it is larger than our default 61 // page size. If it is, we allocate an entire chunk for it. This is to 62 // support gigantic tokens, which almost certainly won't happen. :) 63 if (RequestLen < ScratchBufSize) 64 RequestLen = ScratchBufSize; 65 66 llvm::MemoryBuffer *Buf = 67 llvm::MemoryBuffer::getNewMemBuffer(RequestLen, "<scratch space>"); 68 FileID FID = SourceMgr.createFileIDForMemBuffer(Buf); 69 BufferStartLoc = SourceMgr.getLocForStartOfFile(FID); 70 CurBuffer = const_cast<char*>(Buf->getBufferStart()); 71 BytesUsed = 1; 72 CurBuffer[0] = '0'; // Start out with a \0 for cleanliness. 73 } 74
