MemoryBuffer.h revision 199511 
1//===--- MemoryBuffer.h - Memory Buffer Interface ---------------*- C++ -*-===//
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 defines the MemoryBuffer interface.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_SUPPORT_MEMORYBUFFER_H
15#define LLVM_SUPPORT_MEMORYBUFFER_H
16
17#include "llvm/ADT/StringRef.h"
18#include "llvm/System/DataTypes.h"
19#include <string>
20
21namespace llvm {
22
23/// MemoryBuffer - This interface provides simple read-only access to a block
24/// of memory, and provides simple methods for reading files and standard input
25/// into a memory buffer.  In addition to basic access to the characters in the
26/// file, this interface guarantees you can read one character past the end of
27/// the file, and that this character will read as '\0'.
28class MemoryBuffer {
29  const char *BufferStart; // Start of the buffer.
30  const char *BufferEnd;   // End of the buffer.
31
32  /// MustDeleteBuffer - True if we allocated this buffer.  If so, the
33  /// destructor must know the delete[] it.
34  bool MustDeleteBuffer;
35protected:
36  MemoryBuffer() : MustDeleteBuffer(false) {}
37  void init(const char *BufStart, const char *BufEnd);
38  void initCopyOf(const char *BufStart, const char *BufEnd);
39public:
40  virtual ~MemoryBuffer();
41
42  const char *getBufferStart() const { return BufferStart; }
43  const char *getBufferEnd() const   { return BufferEnd; }
44  size_t getBufferSize() const { return BufferEnd-BufferStart; }
45
46  StringRef getBuffer() const {
47    return StringRef(BufferStart, getBufferSize());
48  }
49
50  /// getBufferIdentifier - Return an identifier for this buffer, typically the
51  /// filename it was read from.
52  virtual const char *getBufferIdentifier() const {
53    return "Unknown buffer";
54  }
55
56  /// getFile - Open the specified file as a MemoryBuffer, returning a new
57  /// MemoryBuffer if successful, otherwise returning null.  If FileSize is
58  /// specified, this means that the client knows that the file exists and that
59  /// it has the specified size.
60  static MemoryBuffer *getFile(StringRef Filename,
61                               std::string *ErrStr = 0,
62                               int64_t FileSize = -1);
63
64  /// getMemBuffer - Open the specified memory range as a MemoryBuffer.  Note
65  /// that EndPtr[0] must be a null byte and be accessible!
66  static MemoryBuffer *getMemBuffer(const char *StartPtr, const char *EndPtr,
67                                    const char *BufferName = "");
68
69  /// getMemBufferCopy - Open the specified memory range as a MemoryBuffer,
70  /// copying the contents and taking ownership of it.  This has no requirements
71  /// on EndPtr[0].
72  static MemoryBuffer *getMemBufferCopy(const char *StartPtr,const char *EndPtr,
73                                        const char *BufferName = "");
74
75  /// getNewMemBuffer - Allocate a new MemoryBuffer of the specified size that
76  /// is completely initialized to zeros.  Note that the caller should
77  /// initialize the memory allocated by this method.  The memory is owned by
78  /// the MemoryBuffer object.
79  static MemoryBuffer *getNewMemBuffer(size_t Size,
80                                       const char *BufferName = "");
81
82  /// getNewUninitMemBuffer - Allocate a new MemoryBuffer of the specified size
83  /// that is not initialized.  Note that the caller should initialize the
84  /// memory allocated by this method.  The memory is owned by the MemoryBuffer
85  /// object.
86  static MemoryBuffer *getNewUninitMemBuffer(size_t Size,
87                                             StringRef BufferName = "");
88
89  /// getSTDIN - Read all of stdin into a file buffer, and return it.
90  static MemoryBuffer *getSTDIN();
91
92
93  /// getFileOrSTDIN - Open the specified file as a MemoryBuffer, or open stdin
94  /// if the Filename is "-".  If an error occurs, this returns null and fills
95  /// in *ErrStr with a reason.
96  static MemoryBuffer *getFileOrSTDIN(StringRef Filename,
97                                      std::string *ErrStr = 0,
98                                      int64_t FileSize = -1);
99};
100
101} // end namespace llvm
102
103#endif
104