antlr
Class InputBuffer

java.lang.Object
  antlr.InputBuffer

Direct Known Subclasses:

ByteBuffer, CharBuffer, DebuggingInputBuffer

public abstract class InputBuffer

extends java.lang.Object

A Stream of characters fed to the lexer from a InputStream that can be rewound via mark()/rewind() methods.

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.

See Also:

CharQueue

Constructor Summary

InputBuffer()           Create an input buffer

 

Method Summary
void	commit()           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.
void	consume()           Mark another character for deferred consumption
abstract  void	fill(int amount)           Ensure that the input buffer is sufficiently full
java.lang.String	getLAChars()
java.lang.String	getMarkedChars()
boolean	isMarked()
char	LA(int i)           Get a lookahead character
int	mark()           Return an integer marker that can be used to rewind the buffer to its current state.
void	reset()           Reset the input buffer
void	rewind(int mark)           Rewind the character buffer to a marker.

 

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

 

Constructor Detail

InputBuffer

public InputBuffer()

Create an input buffer

commit

public void commit()

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.

consume

public void consume()

Mark another character for deferred consumption

fill

public abstract void fill(int amount)
                   throws CharStreamException

Ensure that the input buffer is sufficiently full

Throws:

CharStreamException

getLAChars

public java.lang.String getLAChars()

getMarkedChars

public java.lang.String getMarkedChars()

isMarked

public boolean isMarked()

LA

public char LA(int i)
        throws CharStreamException

Get a lookahead character

Throws:

CharStreamException

mark

public int mark()

Return an integer marker that can be used to rewind the buffer to its current state.

rewind

public void rewind(int mark)

Rewind the character buffer to a marker.

Parameters:

mark - Marker returned previously from mark()

reset

public void reset()

Reset the input buffer