src/antlr/InputBuffer.hpp

#ifndef INC_InputBuffer_hpp__
#define INC_InputBuffer_hpp__

/* ANTLR Translator Generator
 * Project led by Terence Parr at http://www.jGuru.com
 * Software rights: http://www.antlr.org/license.html
 *
 * $Id: InputBuffer.hpp,v 1.1 2005-12-02 15:38:02 tim Exp $
 */

#include <antlr/config.hpp>
#include <antlr/CircularQueue.hpp>
#include <string>

#ifdef ANTLR_CXX_SUPPORTS_NAMESPACE
namespace antlr {
#endif

/** A Stream of characters fed to the lexer from a InputStream that can
 * be rewound via mark()/rewind() methods.
 * <p>
 * A dynamic array is used to buffer up all the input characters.  Normally,
 * "k" characters are stored in the buffer.  More characters may be stored during
 * guess mode (testing syntactic predicate), or when LT(i>k) is referenced.
 * Consumption of characters is deferred.  In other words, reading the next
 * character is not done by conume(), but deferred until needed by LA or LT.
 * <p>
 *
 * @see antlr.CharQueue
 */
class ANTLR_API InputBuffer {
public:
        /** Create a character buffer */
        InputBuffer()
        : nMarkers(0)
        , markerOffset(0)
        , numToConsume(0)
        {
        }

        virtual ~InputBuffer()
        {
        }

        /// Reset the input buffer to empty state
        virtual inline void reset( void )
        {
                nMarkers = 0;
                markerOffset = 0;
                numToConsume = 0;
                queue.clear();
        }

        /** This method updates the state of the input buffer so that
         * the text matched since the most recent mark() is no longer
         * held by the buffer.  So, you either do a mark/rewind for
         * failed predicate or mark/commit to keep on parsing without
         * rewinding the input.
         */
        inline void commit( void )
        {
                nMarkers--;
        }

        /** Mark another character for deferred consumption */
        virtual inline void consume()
        {
                numToConsume++;
        }

        /** Ensure that the character buffer is sufficiently full */
        virtual void fill(unsigned int amount);

        /** Override this in subclasses to get the next character */
        virtual int getChar()=0;

        /** Get a lookahead character */
        virtual inline int LA(unsigned int i)
        {
                fill(i);
                return queue.elementAt(markerOffset + i - 1);
        }

        /** Return an integer marker that can be used to rewind the buffer to
         * its current state.
         */
        virtual unsigned int mark();
        /// Are there any marks active in the InputBuffer
        virtual inline bool isMarked() const
        {
                return (nMarkers != 0);
        }
        /** Rewind the character buffer to a marker.
         * @param mark Marker returned previously from mark()
         */
        virtual void rewind(unsigned int mark);

        /** Get the number of non-consumed characters
         */
        virtual unsigned int entries() const;

        ANTLR_USE_NAMESPACE(std)string getLAChars() const;

        ANTLR_USE_NAMESPACE(std)string getMarkedChars() const;

protected:
        // char source
        // leave to subclasses

        // Number of active markers
        unsigned int nMarkers; // = 0;

        // Additional offset used when markers are active
        unsigned int markerOffset; // = 0;

        // Number of calls to consume() since last LA() or LT() call
        unsigned int numToConsume; // = 0;

        // Circular queue
        CircularQueue<int> queue;

        /** Sync up deferred consumption */
        void syncConsume();

private:
        InputBuffer(const InputBuffer& other);
        InputBuffer& operator=(const InputBuffer& other);
};

/** Sync up deferred consumption */
inline void InputBuffer::syncConsume() {
        if (numToConsume > 0)
        {
                if (nMarkers > 0)
                        markerOffset += numToConsume;
                else
                        queue.removeItems( numToConsume );
                numToConsume = 0;
        }
}

#ifdef ANTLR_CXX_SUPPORTS_NAMESPACE
}
#endif

#endif //INC_InputBuffer_hpp__
Revision:	2469
Committed:	Fri Dec 2 15:38:03 2005 UTC (18 years, 8 months ago) by tim
File size:	3484 byte(s)
Log Message:	End of the Link --> List Return of the Oject-Oriented replace yacc/lex parser with antlr parser
#	User	Rev	Content
1	tim	2469	#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			* $Id: InputBuffer.hpp,v 1.1 2005-12-02 15:38:02 tim Exp $
9			*/
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__