267 lines
10 KiB
C
267 lines
10 KiB
C
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//===--- MemoryBuffer.h - Memory Buffer Interface ---------------*- C++ -*-===//
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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 defines the MemoryBuffer interface.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_MEMORYBUFFER_H
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#define LLVM_SUPPORT_MEMORYBUFFER_H
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#include "llvm-c/Types.h"
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#include "llvm/ADT/ArrayRef.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/Support/CBindingWrapping.h"
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#include "llvm/Support/ErrorOr.h"
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#include "llvm/Support/MemoryBufferRef.h"
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#include <cstddef>
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#include <cstdint>
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#include <memory>
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namespace llvm {
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namespace sys {
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namespace fs {
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// Duplicated from FileSystem.h to avoid a dependency.
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#if defined(_WIN32)
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// A Win32 HANDLE is a typedef of void*
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using file_t = void *;
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#else
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using file_t = int;
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#endif
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} // namespace fs
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} // namespace sys
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/// This interface provides simple read-only access to a block of memory, and
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/// provides simple methods for reading files and standard input into a memory
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/// buffer. In addition to basic access to the characters in the file, this
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/// interface guarantees you can read one character past the end of the file,
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/// and that this character will read as '\0'.
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///
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/// The '\0' guarantee is needed to support an optimization -- it's intended to
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/// be more efficient for clients which are reading all the data to stop
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/// reading when they encounter a '\0' than to continually check the file
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/// position to see if it has reached the end of the file.
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class MemoryBuffer {
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const char *BufferStart; // Start of the buffer.
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const char *BufferEnd; // End of the buffer.
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protected:
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MemoryBuffer() = default;
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void init(const char *BufStart, const char *BufEnd,
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bool RequiresNullTerminator);
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public:
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MemoryBuffer(const MemoryBuffer &) = delete;
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MemoryBuffer &operator=(const MemoryBuffer &) = delete;
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virtual ~MemoryBuffer();
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const char *getBufferStart() const { return BufferStart; }
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const char *getBufferEnd() const { return BufferEnd; }
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size_t getBufferSize() const { return BufferEnd-BufferStart; }
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StringRef getBuffer() const {
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return StringRef(BufferStart, getBufferSize());
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}
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/// Return an identifier for this buffer, typically the filename it was read
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/// from.
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virtual StringRef getBufferIdentifier() const { return "Unknown buffer"; }
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/// Open the specified file as a MemoryBuffer, returning a new MemoryBuffer
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/// if successful, otherwise returning null. If FileSize is specified, this
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/// means that the client knows that the file exists and that it has the
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/// specified size.
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///
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/// \param IsVolatile Set to true to indicate that the contents of the file
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/// can change outside the user's control, e.g. when libclang tries to parse
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/// while the user is editing/updating the file or if the file is on an NFS.
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static ErrorOr<std::unique_ptr<MemoryBuffer>>
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getFile(const Twine &Filename, int64_t FileSize = -1,
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bool RequiresNullTerminator = true, bool IsVolatile = false);
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/// Read all of the specified file into a MemoryBuffer as a stream
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/// (i.e. until EOF reached). This is useful for special files that
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/// look like a regular file but have 0 size (e.g. /proc/cpuinfo on Linux).
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static ErrorOr<std::unique_ptr<MemoryBuffer>>
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getFileAsStream(const Twine &Filename);
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/// Given an already-open file descriptor, map some slice of it into a
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/// MemoryBuffer. The slice is specified by an \p Offset and \p MapSize.
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/// Since this is in the middle of a file, the buffer is not null terminated.
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static ErrorOr<std::unique_ptr<MemoryBuffer>>
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getOpenFileSlice(sys::fs::file_t FD, const Twine &Filename, uint64_t MapSize,
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int64_t Offset, bool IsVolatile = false);
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/// Given an already-open file descriptor, read the file and return a
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/// MemoryBuffer.
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///
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/// \param IsVolatile Set to true to indicate that the contents of the file
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/// can change outside the user's control, e.g. when libclang tries to parse
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/// while the user is editing/updating the file or if the file is on an NFS.
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static ErrorOr<std::unique_ptr<MemoryBuffer>>
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getOpenFile(sys::fs::file_t FD, const Twine &Filename, uint64_t FileSize,
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bool RequiresNullTerminator = true, bool IsVolatile = false);
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/// Open the specified memory range as a MemoryBuffer. Note that InputData
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/// must be null terminated if RequiresNullTerminator is true.
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static std::unique_ptr<MemoryBuffer>
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getMemBuffer(StringRef InputData, StringRef BufferName = "",
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bool RequiresNullTerminator = true);
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static std::unique_ptr<MemoryBuffer>
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getMemBuffer(MemoryBufferRef Ref, bool RequiresNullTerminator = true);
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/// Open the specified memory range as a MemoryBuffer, copying the contents
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/// and taking ownership of it. InputData does not have to be null terminated.
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static std::unique_ptr<MemoryBuffer>
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getMemBufferCopy(StringRef InputData, const Twine &BufferName = "");
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/// Read all of stdin into a file buffer, and return it.
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static ErrorOr<std::unique_ptr<MemoryBuffer>> getSTDIN();
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/// Open the specified file as a MemoryBuffer, or open stdin if the Filename
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/// is "-".
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static ErrorOr<std::unique_ptr<MemoryBuffer>>
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getFileOrSTDIN(const Twine &Filename, int64_t FileSize = -1,
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bool RequiresNullTerminator = true);
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/// Map a subrange of the specified file as a MemoryBuffer.
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static ErrorOr<std::unique_ptr<MemoryBuffer>>
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getFileSlice(const Twine &Filename, uint64_t MapSize, uint64_t Offset,
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bool IsVolatile = false);
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//===--------------------------------------------------------------------===//
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// Provided for performance analysis.
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//===--------------------------------------------------------------------===//
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/// The kind of memory backing used to support the MemoryBuffer.
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enum BufferKind {
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MemoryBuffer_Malloc,
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MemoryBuffer_MMap
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};
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/// Return information on the memory mechanism used to support the
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/// MemoryBuffer.
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virtual BufferKind getBufferKind() const = 0;
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MemoryBufferRef getMemBufferRef() const;
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};
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/// This class is an extension of MemoryBuffer, which allows copy-on-write
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/// access to the underlying contents. It only supports creation methods that
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/// are guaranteed to produce a writable buffer. For example, mapping a file
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/// read-only is not supported.
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class WritableMemoryBuffer : public MemoryBuffer {
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protected:
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WritableMemoryBuffer() = default;
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public:
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using MemoryBuffer::getBuffer;
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using MemoryBuffer::getBufferEnd;
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using MemoryBuffer::getBufferStart;
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// const_cast is well-defined here, because the underlying buffer is
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// guaranteed to have been initialized with a mutable buffer.
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char *getBufferStart() {
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return const_cast<char *>(MemoryBuffer::getBufferStart());
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}
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char *getBufferEnd() {
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return const_cast<char *>(MemoryBuffer::getBufferEnd());
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}
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MutableArrayRef<char> getBuffer() {
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return {getBufferStart(), getBufferEnd()};
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}
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static ErrorOr<std::unique_ptr<WritableMemoryBuffer>>
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getFile(const Twine &Filename, int64_t FileSize = -1,
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bool IsVolatile = false);
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/// Map a subrange of the specified file as a WritableMemoryBuffer.
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static ErrorOr<std::unique_ptr<WritableMemoryBuffer>>
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getFileSlice(const Twine &Filename, uint64_t MapSize, uint64_t Offset,
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bool IsVolatile = false);
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/// Allocate a new MemoryBuffer of the specified size that is not initialized.
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/// Note that the caller should initialize the memory allocated by this
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/// method. The memory is owned by the MemoryBuffer object.
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static std::unique_ptr<WritableMemoryBuffer>
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getNewUninitMemBuffer(size_t Size, const Twine &BufferName = "");
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/// Allocate a new zero-initialized MemoryBuffer of the specified size. Note
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/// that the caller need not initialize the memory allocated by this method.
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/// The memory is owned by the MemoryBuffer object.
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static std::unique_ptr<WritableMemoryBuffer>
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getNewMemBuffer(size_t Size, const Twine &BufferName = "");
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private:
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// Hide these base class factory function so one can't write
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// WritableMemoryBuffer::getXXX()
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// and be surprised that he got a read-only Buffer.
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using MemoryBuffer::getFileAsStream;
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using MemoryBuffer::getFileOrSTDIN;
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using MemoryBuffer::getMemBuffer;
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using MemoryBuffer::getMemBufferCopy;
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using MemoryBuffer::getOpenFile;
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using MemoryBuffer::getOpenFileSlice;
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using MemoryBuffer::getSTDIN;
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};
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/// This class is an extension of MemoryBuffer, which allows write access to
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/// the underlying contents and committing those changes to the original source.
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/// It only supports creation methods that are guaranteed to produce a writable
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/// buffer. For example, mapping a file read-only is not supported.
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class WriteThroughMemoryBuffer : public MemoryBuffer {
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protected:
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WriteThroughMemoryBuffer() = default;
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public:
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using MemoryBuffer::getBuffer;
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using MemoryBuffer::getBufferEnd;
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using MemoryBuffer::getBufferStart;
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// const_cast is well-defined here, because the underlying buffer is
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// guaranteed to have been initialized with a mutable buffer.
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char *getBufferStart() {
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return const_cast<char *>(MemoryBuffer::getBufferStart());
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}
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char *getBufferEnd() {
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return const_cast<char *>(MemoryBuffer::getBufferEnd());
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}
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MutableArrayRef<char> getBuffer() {
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return {getBufferStart(), getBufferEnd()};
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}
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static ErrorOr<std::unique_ptr<WriteThroughMemoryBuffer>>
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getFile(const Twine &Filename, int64_t FileSize = -1);
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/// Map a subrange of the specified file as a ReadWriteMemoryBuffer.
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static ErrorOr<std::unique_ptr<WriteThroughMemoryBuffer>>
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getFileSlice(const Twine &Filename, uint64_t MapSize, uint64_t Offset);
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private:
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// Hide these base class factory function so one can't write
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// WritableMemoryBuffer::getXXX()
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// and be surprised that he got a read-only Buffer.
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using MemoryBuffer::getFileAsStream;
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using MemoryBuffer::getFileOrSTDIN;
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using MemoryBuffer::getMemBuffer;
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using MemoryBuffer::getMemBufferCopy;
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using MemoryBuffer::getOpenFile;
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using MemoryBuffer::getOpenFileSlice;
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using MemoryBuffer::getSTDIN;
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};
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// Create wrappers for C Binding types (see CBindingWrapping.h).
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DEFINE_SIMPLE_CONVERSION_FUNCTIONS(MemoryBuffer, LLVMMemoryBufferRef)
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} // end namespace llvm
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#endif // LLVM_SUPPORT_MEMORYBUFFER_H
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