1 //===-- DataBuffer.h --------------------------------------------*- 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 #ifndef liblldb_DataBuffer_h_
11 #define liblldb_DataBuffer_h_
12 #if defined(__cplusplus)
13 
14 #include <stdint.h>
15 #include <string.h>
16 
17 #include "lldb/lldb-types.h"
18 
19 #include "llvm/ADT/ArrayRef.h"
20 
21 namespace lldb_private {
22 
23 //----------------------------------------------------------------------
24 /// @class DataBuffer DataBuffer.h "lldb/Core/DataBuffer.h"
25 /// A pure virtual protocol class for abstracted data buffers.
26 ///
27 /// DataBuffer is an abstract class that gets packaged into a shared pointer
28 /// that can use to implement various ways to store data (on the heap, memory
29 /// mapped, cached inferior memory). It gets used by DataExtractor so many
30 /// DataExtractor objects can share the same data and sub-ranges of that
31 /// shared data, and the last object that contains a reference to the shared
32 /// data will free it.
33 ///
34 /// Subclasses can implement as many different constructors or member
35 /// functions that allow data to be stored in the object's buffer prior to
36 /// handing the shared data to clients that use these buffers.
37 ///
38 /// All subclasses must override all of the pure virtual functions as they are
39 /// used by clients to access the data. Having a common interface allows
40 /// different ways of storing data, yet using it in one common way.
41 ///
42 /// This class currently expects all data to be available without any extra
43 /// calls being made, but we can modify it to optionally get data on demand
44 /// with some extra function calls to load the data before it gets accessed.
45 //----------------------------------------------------------------------
46 class DataBuffer {
47 public:
48   //------------------------------------------------------------------
49   /// Destructor
50   ///
51   /// The destructor is virtual as other classes will inherit from this class
52   /// and be downcast to the DataBuffer pure virtual interface. The virtual
53   /// destructor ensures that destructing the base class will destruct the
54   /// class that inherited from it correctly.
55   //------------------------------------------------------------------
~DataBuffer()56   virtual ~DataBuffer() {}
57 
58   //------------------------------------------------------------------
59   /// Get a pointer to the data.
60   ///
61   /// @return
62   ///     A pointer to the bytes owned by this object, or NULL if the
63   ///     object contains no bytes.
64   //------------------------------------------------------------------
65   virtual uint8_t *GetBytes() = 0;
66 
67   //------------------------------------------------------------------
68   /// Get a const pointer to the data.
69   ///
70   /// @return
71   ///     A const pointer to the bytes owned by this object, or NULL
72   ///     if the object contains no bytes.
73   //------------------------------------------------------------------
74   virtual const uint8_t *GetBytes() const = 0;
75 
76   //------------------------------------------------------------------
77   /// Get the number of bytes in the data buffer.
78   ///
79   /// @return
80   ///     The number of bytes this object currently contains.
81   //------------------------------------------------------------------
82   virtual lldb::offset_t GetByteSize() const = 0;
83 
GetData()84   llvm::ArrayRef<uint8_t> GetData() const {
85     return llvm::ArrayRef<uint8_t>(GetBytes(), GetByteSize());
86   }
87 
GetData()88   llvm::MutableArrayRef<uint8_t> GetData() {
89     return llvm::MutableArrayRef<uint8_t>(GetBytes(), GetByteSize());
90   }
91 };
92 
93 } // namespace lldb_private
94 
95 #endif /// #if defined(__cplusplus)
96 #endif /// lldb_DataBuffer_h_
97