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