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to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
84 lines
3.3 KiB
C++
84 lines
3.3 KiB
C++
//===--- ScratchBuffer.cpp - Scratch space for forming tokens -------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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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)
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: SourceMgr(SM), CurBuffer(nullptr) {
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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+2 > ScratchBufSize)
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AllocScratchBuffer(Len+2);
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else {
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// Clear out the source line cache if it's already been computed.
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// FIXME: Allow this to be incrementally extended.
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auto *ContentCache = const_cast<SrcMgr::ContentCache *>(
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SourceMgr.getSLocEntry(SourceMgr.getFileID(BufferStartLoc))
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.getFile().getContentCache());
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ContentCache->SourceLineCache = nullptr;
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}
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// Prefix the token with a \n, so that it looks like it is the first thing on
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// its own virtual line in caret diagnostics.
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CurBuffer[BytesUsed++] = '\n';
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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+1;
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// Add a NUL terminator to the token. This keeps the tokens separated, in
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// case they get relexed, and puts them on their own virtual lines in case a
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// diagnostic points to one.
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CurBuffer[BytesUsed-1] = '\0';
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return BufferStartLoc.getLocWithOffset(BytesUsed-Len-1);
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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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// Get scratch buffer. Zero-initialize it so it can be dumped into a PCH file
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// deterministically.
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std::unique_ptr<llvm::WritableMemoryBuffer> OwnBuf =
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llvm::WritableMemoryBuffer::getNewMemBuffer(RequestLen,
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"<scratch space>");
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CurBuffer = OwnBuf->getBufferStart();
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FileID FID = SourceMgr.createFileID(std::move(OwnBuf));
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BufferStartLoc = SourceMgr.getLocForStartOfFile(FID);
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BytesUsed = 0;
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}
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