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Diffstat (limited to 'poxml/antlr/src/InputBuffer.cpp')
| -rw-r--r-- | poxml/antlr/src/InputBuffer.cpp | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/poxml/antlr/src/InputBuffer.cpp b/poxml/antlr/src/InputBuffer.cpp new file mode 100644 index 00000000..058c32ab --- /dev/null +++ b/poxml/antlr/src/InputBuffer.cpp @@ -0,0 +1,109 @@ +/** + * <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" + +ANTLR_BEGIN_NAMESPACE(antlr) + +/** 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); +} + +/**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--; +} + +ANTLR_END_NAMESPACE + |