| 1 |
tim |
770 |
#ifndef INC_InputBuffer_hpp__ |
| 2 |
|
|
#define INC_InputBuffer_hpp__ |
| 3 |
|
|
|
| 4 |
|
|
/* ANTLR Translator Generator |
| 5 |
|
|
* Project led by Terence Parr at http://www.jGuru.com |
| 6 |
|
|
* Software rights: http://www.antlr.org/license.html |
| 7 |
|
|
* |
| 8 |
gezelter |
1442 |
* $Id$ |
| 9 |
tim |
770 |
*/ |
| 10 |
|
|
|
| 11 |
|
|
#include <antlr/config.hpp> |
| 12 |
|
|
#include <antlr/CircularQueue.hpp> |
| 13 |
|
|
#include <string> |
| 14 |
|
|
|
| 15 |
|
|
#ifdef ANTLR_CXX_SUPPORTS_NAMESPACE |
| 16 |
|
|
namespace antlr { |
| 17 |
|
|
#endif |
| 18 |
|
|
|
| 19 |
|
|
/** A Stream of characters fed to the lexer from a InputStream that can |
| 20 |
|
|
* be rewound via mark()/rewind() methods. |
| 21 |
|
|
* <p> |
| 22 |
|
|
* A dynamic array is used to buffer up all the input characters. Normally, |
| 23 |
|
|
* "k" characters are stored in the buffer. More characters may be stored during |
| 24 |
|
|
* guess mode (testing syntactic predicate), or when LT(i>k) is referenced. |
| 25 |
|
|
* Consumption of characters is deferred. In other words, reading the next |
| 26 |
|
|
* character is not done by conume(), but deferred until needed by LA or LT. |
| 27 |
|
|
* <p> |
| 28 |
|
|
* |
| 29 |
|
|
* @see antlr.CharQueue |
| 30 |
|
|
*/ |
| 31 |
|
|
class ANTLR_API InputBuffer { |
| 32 |
|
|
public: |
| 33 |
|
|
/** Create a character buffer */ |
| 34 |
|
|
InputBuffer() |
| 35 |
|
|
: nMarkers(0) |
| 36 |
|
|
, markerOffset(0) |
| 37 |
|
|
, numToConsume(0) |
| 38 |
|
|
{ |
| 39 |
|
|
} |
| 40 |
|
|
|
| 41 |
|
|
virtual ~InputBuffer() |
| 42 |
|
|
{ |
| 43 |
|
|
} |
| 44 |
|
|
|
| 45 |
|
|
/// Reset the input buffer to empty state |
| 46 |
|
|
virtual inline void reset( void ) |
| 47 |
|
|
{ |
| 48 |
|
|
nMarkers = 0; |
| 49 |
|
|
markerOffset = 0; |
| 50 |
|
|
numToConsume = 0; |
| 51 |
|
|
queue.clear(); |
| 52 |
|
|
} |
| 53 |
|
|
|
| 54 |
|
|
/** This method updates the state of the input buffer so that |
| 55 |
|
|
* the text matched since the most recent mark() is no longer |
| 56 |
|
|
* held by the buffer. So, you either do a mark/rewind for |
| 57 |
|
|
* failed predicate or mark/commit to keep on parsing without |
| 58 |
|
|
* rewinding the input. |
| 59 |
|
|
*/ |
| 60 |
|
|
inline void commit( void ) |
| 61 |
|
|
{ |
| 62 |
|
|
nMarkers--; |
| 63 |
|
|
} |
| 64 |
|
|
|
| 65 |
|
|
/** Mark another character for deferred consumption */ |
| 66 |
|
|
virtual inline void consume() |
| 67 |
|
|
{ |
| 68 |
|
|
numToConsume++; |
| 69 |
|
|
} |
| 70 |
|
|
|
| 71 |
|
|
/** Ensure that the character buffer is sufficiently full */ |
| 72 |
|
|
virtual void fill(unsigned int amount); |
| 73 |
|
|
|
| 74 |
|
|
/** Override this in subclasses to get the next character */ |
| 75 |
|
|
virtual int getChar()=0; |
| 76 |
|
|
|
| 77 |
|
|
/** Get a lookahead character */ |
| 78 |
|
|
virtual inline int LA(unsigned int i) |
| 79 |
|
|
{ |
| 80 |
|
|
fill(i); |
| 81 |
|
|
return queue.elementAt(markerOffset + i - 1); |
| 82 |
|
|
} |
| 83 |
|
|
|
| 84 |
|
|
/** Return an integer marker that can be used to rewind the buffer to |
| 85 |
|
|
* its current state. |
| 86 |
|
|
*/ |
| 87 |
|
|
virtual unsigned int mark(); |
| 88 |
|
|
/// Are there any marks active in the InputBuffer |
| 89 |
|
|
virtual inline bool isMarked() const |
| 90 |
|
|
{ |
| 91 |
|
|
return (nMarkers != 0); |
| 92 |
|
|
} |
| 93 |
|
|
/** Rewind the character buffer to a marker. |
| 94 |
|
|
* @param mark Marker returned previously from mark() |
| 95 |
|
|
*/ |
| 96 |
|
|
virtual void rewind(unsigned int mark); |
| 97 |
|
|
|
| 98 |
|
|
/** Get the number of non-consumed characters |
| 99 |
|
|
*/ |
| 100 |
|
|
virtual unsigned int entries() const; |
| 101 |
|
|
|
| 102 |
|
|
ANTLR_USE_NAMESPACE(std)string getLAChars() const; |
| 103 |
|
|
|
| 104 |
|
|
ANTLR_USE_NAMESPACE(std)string getMarkedChars() const; |
| 105 |
|
|
|
| 106 |
|
|
protected: |
| 107 |
|
|
// char source |
| 108 |
|
|
// leave to subclasses |
| 109 |
|
|
|
| 110 |
|
|
// Number of active markers |
| 111 |
|
|
unsigned int nMarkers; // = 0; |
| 112 |
|
|
|
| 113 |
|
|
// Additional offset used when markers are active |
| 114 |
|
|
unsigned int markerOffset; // = 0; |
| 115 |
|
|
|
| 116 |
|
|
// Number of calls to consume() since last LA() or LT() call |
| 117 |
|
|
unsigned int numToConsume; // = 0; |
| 118 |
|
|
|
| 119 |
|
|
// Circular queue |
| 120 |
|
|
CircularQueue<int> queue; |
| 121 |
|
|
|
| 122 |
|
|
/** Sync up deferred consumption */ |
| 123 |
|
|
void syncConsume(); |
| 124 |
|
|
|
| 125 |
|
|
private: |
| 126 |
|
|
InputBuffer(const InputBuffer& other); |
| 127 |
|
|
InputBuffer& operator=(const InputBuffer& other); |
| 128 |
|
|
}; |
| 129 |
|
|
|
| 130 |
|
|
/** Sync up deferred consumption */ |
| 131 |
|
|
inline void InputBuffer::syncConsume() { |
| 132 |
|
|
if (numToConsume > 0) |
| 133 |
|
|
{ |
| 134 |
|
|
if (nMarkers > 0) |
| 135 |
|
|
markerOffset += numToConsume; |
| 136 |
|
|
else |
| 137 |
|
|
queue.removeItems( numToConsume ); |
| 138 |
|
|
numToConsume = 0; |
| 139 |
|
|
} |
| 140 |
|
|
} |
| 141 |
|
|
|
| 142 |
|
|
#ifdef ANTLR_CXX_SUPPORTS_NAMESPACE |
| 143 |
|
|
} |
| 144 |
|
|
#endif |
| 145 |
|
|
|
| 146 |
|
|
#endif //INC_InputBuffer_hpp__ |
