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-c/Support.h"
18#include "llvm/ADT/Twine.h"
19#include "llvm/Support/CBindingWrapping.h"
20#include "llvm/Support/DataTypes.h"
21#include "llvm/Support/ErrorOr.h"
22#include <memory>
23
24namespace llvm {
25class MemoryBufferRef;
26
27/// This interface provides simple read-only access to a block of memory, and
28/// provides simple methods for reading files and standard input into a memory
29/// buffer.  In addition to basic access to the characters in the file, this
30/// interface guarantees you can read one character past the end of the file,
31/// and that this character will read as '\0'.
32///
33/// The '\0' guarantee is needed to support an optimization -- it's intended to
34/// be more efficient for clients which are reading all the data to stop
35/// reading when they encounter a '\0' than to continually check the file
36/// position to see if it has reached the end of the file.
37class MemoryBuffer {
38  const char *BufferStart; // Start of the buffer.
39  const char *BufferEnd;   // End of the buffer.
40
41  MemoryBuffer(const MemoryBuffer &) = delete;
42  MemoryBuffer &operator=(const MemoryBuffer &) = delete;
43protected:
44  MemoryBuffer() {}
45  void init(const char *BufStart, const char *BufEnd,
46            bool RequiresNullTerminator);
47public:
48  virtual ~MemoryBuffer();
49
50  const char *getBufferStart() const { return BufferStart; }
51  const char *getBufferEnd() const   { return BufferEnd; }
52  size_t getBufferSize() const { return BufferEnd-BufferStart; }
53
54  StringRef getBuffer() const {
55    return StringRef(BufferStart, getBufferSize());
56  }
57
58  /// Return an identifier for this buffer, typically the filename it was read
59  /// from.
60  virtual const char *getBufferIdentifier() const {
61    return "Unknown buffer";
62  }
63
64  /// Open the specified file as a MemoryBuffer, returning a new MemoryBuffer
65  /// if successful, otherwise returning null. If FileSize is specified, this
66  /// means that the client knows that the file exists and that it has the
67  /// specified size.
68  ///
69  /// \param IsVolatileSize Set to true to indicate that the file size may be
70  /// changing, e.g. when libclang tries to parse while the user is
71  /// editing/updating the file.
72  static ErrorOr<std::unique_ptr<MemoryBuffer>>
73  getFile(const Twine &Filename, int64_t FileSize = -1,
74          bool RequiresNullTerminator = true, bool IsVolatileSize = false);
75
76  /// Given an already-open file descriptor, map some slice of it into a
77  /// MemoryBuffer. The slice is specified by an \p Offset and \p MapSize.
78  /// Since this is in the middle of a file, the buffer is not null terminated.
79  static ErrorOr<std::unique_ptr<MemoryBuffer>>
80  getOpenFileSlice(int FD, const Twine &Filename, uint64_t MapSize,
81                   int64_t Offset);
82
83  /// Given an already-open file descriptor, read the file and return a
84  /// MemoryBuffer.
85  ///
86  /// \param IsVolatileSize Set to true to indicate that the file size may be
87  /// changing, e.g. when libclang tries to parse while the user is
88  /// editing/updating the file.
89  static ErrorOr<std::unique_ptr<MemoryBuffer>>
90  getOpenFile(int FD, const Twine &Filename, uint64_t FileSize,
91              bool RequiresNullTerminator = true, bool IsVolatileSize = false);
92
93  /// Open the specified memory range as a MemoryBuffer. Note that InputData
94  /// must be null terminated if RequiresNullTerminator is true.
95  static std::unique_ptr<MemoryBuffer>
96  getMemBuffer(StringRef InputData, StringRef BufferName = "",
97               bool RequiresNullTerminator = true);
98
99  static std::unique_ptr<MemoryBuffer>
100  getMemBuffer(MemoryBufferRef Ref, bool RequiresNullTerminator = true);
101
102  /// Open the specified memory range as a MemoryBuffer, copying the contents
103  /// and taking ownership of it. InputData does not have to be null terminated.
104  static std::unique_ptr<MemoryBuffer>
105  getMemBufferCopy(StringRef InputData, const Twine &BufferName = "");
106
107  /// Allocate a new zero-initialized MemoryBuffer of the specified size. Note
108  /// that the caller need not initialize the memory allocated by this method.
109  /// The memory is owned by the MemoryBuffer object.
110  static std::unique_ptr<MemoryBuffer>
111  getNewMemBuffer(size_t Size, StringRef BufferName = "");
112
113  /// Allocate a new MemoryBuffer of the specified size that is not initialized.
114  /// Note that the caller should initialize the memory allocated by this
115  /// method. The memory is owned by the MemoryBuffer object.
116  static std::unique_ptr<MemoryBuffer>
117  getNewUninitMemBuffer(size_t Size, const Twine &BufferName = "");
118
119  /// Read all of stdin into a file buffer, and return it.
120  static ErrorOr<std::unique_ptr<MemoryBuffer>> getSTDIN();
121
122  /// Open the specified file as a MemoryBuffer, or open stdin if the Filename
123  /// is "-".
124  static ErrorOr<std::unique_ptr<MemoryBuffer>>
125  getFileOrSTDIN(const Twine &Filename, int64_t FileSize = -1);
126
127  /// Map a subrange of the the specified file as a MemoryBuffer.
128  static ErrorOr<std::unique_ptr<MemoryBuffer>>
129  getFileSlice(const Twine &Filename, uint64_t MapSize, uint64_t Offset);
130
131  //===--------------------------------------------------------------------===//
132  // Provided for performance analysis.
133  //===--------------------------------------------------------------------===//
134
135  /// The kind of memory backing used to support the MemoryBuffer.
136  enum BufferKind {
137    MemoryBuffer_Malloc,
138    MemoryBuffer_MMap
139  };
140
141  /// Return information on the memory mechanism used to support the
142  /// MemoryBuffer.
143  virtual BufferKind getBufferKind() const = 0;
144
145  MemoryBufferRef getMemBufferRef() const;
146};
147
148class MemoryBufferRef {
149  StringRef Buffer;
150  StringRef Identifier;
151
152public:
153  MemoryBufferRef() {}
154  MemoryBufferRef(StringRef Buffer, StringRef Identifier)
155      : Buffer(Buffer), Identifier(Identifier) {}
156
157  StringRef getBuffer() const { return Buffer; }
158
159  StringRef getBufferIdentifier() const { return Identifier; }
160
161  const char *getBufferStart() const { return Buffer.begin(); }
162  const char *getBufferEnd() const { return Buffer.end(); }
163  size_t getBufferSize() const { return Buffer.size(); }
164};
165
166// Create wrappers for C Binding types (see CBindingWrapping.h).
167DEFINE_SIMPLE_CONVERSION_FUNCTIONS(MemoryBuffer, LLVMMemoryBufferRef)
168
169} // end namespace llvm
170
171#endif
172