1 //===--- ScratchBuffer.cpp - Scratch space for forming tokens -------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the ScratchBuffer interface.
12 //===----------------------------------------------------------------------===//
14 #include "clang/Lex/ScratchBuffer.h"
15 #include "clang/Basic/SourceManager.h"
16 #include "llvm/Support/MemoryBuffer.h"
18 using namespace clang
;
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;
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
;
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
33 SourceLocation
ScratchBuffer::getToken(const char *Buf
, unsigned Len
,
34 const char *&DestPtr
) {
35 if (BytesUsed
+Len
+2 > ScratchBufSize
)
36 AllocScratchBuffer(Len
+2);
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';
42 // Return a pointer to the character data.
43 DestPtr
= CurBuffer
+BytesUsed
;
45 // Copy the token data into the buffer.
46 memcpy(CurBuffer
+BytesUsed
, Buf
, Len
);
48 // Remember that we used these bytes.
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';
56 return BufferStartLoc
.getFileLocWithOffset(BytesUsed
-Len
-1);
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
;
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());
72 CurBuffer
[0] = '0'; // Start out with a \0 for cleanliness.