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/Support/Compiler.h"
19#include "llvm/Support/DataTypes.h"
20
21namespace llvm {
22
23class error_code;
24template<class T> class OwningPtr;
25
26/// MemoryBuffer - This interface provides simple read-only access to a block
27/// of memory, and provides simple methods for reading files and standard input
28/// into a memory buffer.  In addition to basic access to the characters in the
29/// file, this interface guarantees you can read one character past the end of
30/// the file, and that this character will read as '\0'.
31///
32/// The '\0' guarantee is needed to support an optimization -- it's intended to
33/// be more efficient for clients which are reading all the data to stop
34/// reading when they encounter a '\0' than to continually check the file
35/// position to see if it has reached the end of the file.
36class MemoryBuffer {
37  const char *BufferStart; // Start of the buffer.
38  const char *BufferEnd;   // End of the buffer.
39
40  MemoryBuffer(const MemoryBuffer &) LLVM_DELETED_FUNCTION;
41  MemoryBuffer &operator=(const MemoryBuffer &) LLVM_DELETED_FUNCTION;
42protected:
43  MemoryBuffer() {}
44  void init(const char *BufStart, const char *BufEnd,
45            bool RequiresNullTerminator);
46public:
47  virtual ~MemoryBuffer();
48
49  const char *getBufferStart() const { return BufferStart; }
50  const char *getBufferEnd() const   { return BufferEnd; }
51  size_t getBufferSize() const { return BufferEnd-BufferStart; }
52
53  StringRef getBuffer() const {
54    return StringRef(BufferStart, getBufferSize());
55  }
56
57  /// getBufferIdentifier - Return an identifier for this buffer, typically the
58  /// filename it was read from.
59  virtual const char *getBufferIdentifier() const {
60    return "Unknown buffer";
61  }
62
63  /// getFile - Open the specified file as a MemoryBuffer, returning a new
64  /// MemoryBuffer if successful, otherwise returning null.  If FileSize is
65  /// specified, this means that the client knows that the file exists and that
66  /// it has the specified size.
67  static error_code getFile(StringRef Filename, OwningPtr<MemoryBuffer> &result,
68                            int64_t FileSize = -1,
69                            bool RequiresNullTerminator = true);
70  static error_code getFile(const char *Filename,
71                            OwningPtr<MemoryBuffer> &result,
72                            int64_t FileSize = -1,
73                            bool RequiresNullTerminator = true);
74
75  /// getOpenFile - Given an already-open file descriptor, read the file and
76  /// return a MemoryBuffer.
77  static error_code getOpenFile(int FD, const char *Filename,
78                                OwningPtr<MemoryBuffer> &result,
79                                uint64_t FileSize = -1,
80                                uint64_t MapSize = -1,
81                                int64_t Offset = 0,
82                                bool RequiresNullTerminator = true);
83
84  /// getMemBuffer - Open the specified memory range as a MemoryBuffer.  Note
85  /// that InputData must be null terminated if RequiresNullTerminator is true.
86  static MemoryBuffer *getMemBuffer(StringRef InputData,
87                                    StringRef BufferName = "",
88                                    bool RequiresNullTerminator = true);
89
90  /// getMemBufferCopy - Open the specified memory range as a MemoryBuffer,
91  /// copying the contents and taking ownership of it.  InputData does not
92  /// have to be null terminated.
93  static MemoryBuffer *getMemBufferCopy(StringRef InputData,
94                                        StringRef BufferName = "");
95
96  /// getNewMemBuffer - Allocate a new MemoryBuffer of the specified size that
97  /// is completely initialized to zeros.  Note that the caller should
98  /// initialize the memory allocated by this method.  The memory is owned by
99  /// the MemoryBuffer object.
100  static MemoryBuffer *getNewMemBuffer(size_t Size, StringRef BufferName = "");
101
102  /// getNewUninitMemBuffer - Allocate a new MemoryBuffer of the specified size
103  /// that is not initialized.  Note that the caller should initialize the
104  /// memory allocated by this method.  The memory is owned by the MemoryBuffer
105  /// object.
106  static MemoryBuffer *getNewUninitMemBuffer(size_t Size,
107                                             StringRef BufferName = "");
108
109  /// getSTDIN - Read all of stdin into a file buffer, and return it.
110  /// If an error occurs, this returns null and sets ec.
111  static error_code getSTDIN(OwningPtr<MemoryBuffer> &result);
112
113
114  /// getFileOrSTDIN - Open the specified file as a MemoryBuffer, or open stdin
115  /// if the Filename is "-".  If an error occurs, this returns null and sets
116  /// ec.
117  static error_code getFileOrSTDIN(StringRef Filename,
118                                   OwningPtr<MemoryBuffer> &result,
119                                   int64_t FileSize = -1);
120  static error_code getFileOrSTDIN(const char *Filename,
121                                   OwningPtr<MemoryBuffer> &result,
122                                   int64_t FileSize = -1);
123
124
125  //===--------------------------------------------------------------------===//
126  // Provided for performance analysis.
127  //===--------------------------------------------------------------------===//
128
129  /// The kind of memory backing used to support the MemoryBuffer.
130  enum BufferKind {
131    MemoryBuffer_Malloc,
132    MemoryBuffer_MMap
133  };
134
135  /// Return information on the memory mechanism used to support the
136  /// MemoryBuffer.
137  virtual BufferKind getBufferKind() const = 0;
138};
139
140} // end namespace llvm
141
142#endif
143