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/**
* <b>SOFTWARE RIGHTS</b>
* <p>
* ANTLR 2.6.0 MageLang Insitute, 1998
* <p>
* We reserve no legal rights to the ANTLR--it is fully in the
* public domain. An individual or company may do whatever
* they wish with source code distributed with ANTLR or the
* code generated by ANTLR, including the incorporation of
* ANTLR, or its output, into commerical software.
* <p>
* We encourage users to develop software with ANTLR. However,
* we do ask that credit is given to us for developing
* ANTLR. By "credit", we mean that if you use ANTLR or
* incorporate any source code into one of your programs
* (commercial product, research project, or otherwise) that
* you acknowledge this fact somewhere in the documentation,
* research report, etc... If you like ANTLR and have
* developed a nice tool with the output, please mention that
* you developed it using ANTLR. In addition, we ask that the
* headers remain intact in our source code. As long as these
* guidelines are kept, we expect to continue enhancing this
* system and expect to make other tools available as they are
* completed.
* <p>
* The ANTLR gang:
* @version ANTLR 2.6.0 MageLang Insitute, 1998
* @author Terence Parr, <a href=http://www.MageLang.com>MageLang Institute</a>
* @author <br>John Lilley, <a href=http://www.Empathy.com>Empathy Software</a>
* @author <br><a href="mailto:pete@yamuna.demon.co.uk">Pete Wells</a>
*/
/**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
*/
#include "Antlr/InputBuffer.hpp"
//#include <cstring>
/** Create a character buffer */
InputBuffer::InputBuffer()
: nMarkers(0), markerOffset(0), numToConsume(0)
{}
/** 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.
*/
void InputBuffer::commit()
{
nMarkers--;
}
/** Mark another character for deferred consumption */
void InputBuffer::consume()
{
numToConsume++;
}
/** Ensure that the character buffer is sufficiently full */
void InputBuffer::fill(int amount)
{
syncConsume();
// Fill the buffer sufficiently to hold needed characters
while (queue.entries() < amount + markerOffset) {
// Append the next character
queue.append(getChar());
}
}
bool InputBuffer::isMarked() const
{
return (nMarkers != 0);
}
/** Get a lookahead character */
int InputBuffer::LA(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.
*/
int InputBuffer::mark()
{
syncConsume();
nMarkers++;
return markerOffset;
}
/**Rewind the character buffer to a marker.
* @param mark Marker returned previously from mark()
*/
void InputBuffer::rewind(int mark)
{
syncConsume();
markerOffset = mark;
nMarkers--;
}
/** Sync up deferred consumption */
void InputBuffer::syncConsume() {
while (numToConsume > 0) {
if (nMarkers > 0)
{
// guess mode -- leave leading characters and bump offset.
markerOffset++;
} else {
// normal mode -- remove first character
queue.removeFirst();
}
numToConsume--;
}
}
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