MemoryBuffer.h revision 9f9bd8e4af8c5e7ae02eb5de418a49a6fdafb3f1 
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'.
28///
29/// The '\0' guarantee is needed to support an optimization -- it's intended to
30/// be more efficient for clients which are reading all the data to stop
31/// reading when they encounter a '\0' than to continually check the file
32/// position to see if it has reached the end of the file.
33class MemoryBuffer {
34  const char *BufferStart; // Start of the buffer.
35  const char *BufferEnd;   // End of the buffer.
36
37  MemoryBuffer(const MemoryBuffer &); // DO NOT IMPLEMENT
38  MemoryBuffer &operator=(const MemoryBuffer &); // DO NOT IMPLEMENT
39protected:
40  MemoryBuffer() {}
41  void init(const char *BufStart, const char *BufEnd);
42public:
43  virtual ~MemoryBuffer();
44
45  const char *getBufferStart() const { return BufferStart; }
46  const char *getBufferEnd() const   { return BufferEnd; }
47  size_t getBufferSize() const { return BufferEnd-BufferStart; }
48
49  StringRef getBuffer() const {
50    return StringRef(BufferStart, getBufferSize());
51  }
52
53  /// getBufferIdentifier - Return an identifier for this buffer, typically the
54  /// filename it was read from.
55  virtual const char *getBufferIdentifier() const {
56    return "Unknown buffer";
57  }
58
59  /// getFile - Open the specified file as a MemoryBuffer, returning a new
60  /// MemoryBuffer if successful, otherwise returning null.  If FileSize is
61  /// specified, this means that the client knows that the file exists and that
62  /// it has the specified size.
63  static MemoryBuffer *getFile(StringRef Filename,
64                               std::string *ErrStr = 0,
65                               int64_t FileSize = -1);
66  static MemoryBuffer *getFile(const char *Filename,
67                               std::string *ErrStr = 0,
68                               int64_t FileSize = -1);
69
70  /// getMemBuffer - Open the specified memory range as a MemoryBuffer.  Note
71  /// that InputData must be null terminated.
72  static MemoryBuffer *getMemBuffer(StringRef InputData,
73                                    StringRef BufferName = "");
74
75  /// getMemBufferCopy - Open the specified memory range as a MemoryBuffer,
76  /// copying the contents and taking ownership of it.  InputData does not
77  /// have to be null terminated.
78  static MemoryBuffer *getMemBufferCopy(StringRef InputData,
79                                        StringRef BufferName = "");
80
81  /// getNewMemBuffer - Allocate a new MemoryBuffer of the specified size that
82  /// is completely initialized to zeros.  Note that the caller should
83  /// initialize the memory allocated by this method.  The memory is owned by
84  /// the MemoryBuffer object.
85  static MemoryBuffer *getNewMemBuffer(size_t Size, StringRef BufferName = "");
86
87  /// getNewUninitMemBuffer - Allocate a new MemoryBuffer of the specified size
88  /// that is not initialized.  Note that the caller should initialize the
89  /// memory allocated by this method.  The memory is owned by the MemoryBuffer
90  /// object.
91  static MemoryBuffer *getNewUninitMemBuffer(size_t Size,
92                                             StringRef BufferName = "");
93
94  /// getSTDIN - Read all of stdin into a file buffer, and return it.
95  /// If an error occurs, this returns null and fills in *ErrStr with a reason.
96  static MemoryBuffer *getSTDIN(std::string *ErrStr = 0);
97
98
99  /// getFileOrSTDIN - Open the specified file as a MemoryBuffer, or open stdin
100  /// if the Filename is "-".  If an error occurs, this returns null and fills
101  /// in *ErrStr with a reason.
102  static MemoryBuffer *getFileOrSTDIN(StringRef Filename,
103                                      std::string *ErrStr = 0,
104                                      int64_t FileSize = -1);
105  static MemoryBuffer *getFileOrSTDIN(const char *Filename,
106                                      std::string *ErrStr = 0,
107                                      int64_t FileSize = -1);
108};
109
110} // end namespace llvm
111
112#endif
113