antlr
Class InputBuffer

java.lang.Object
  |
  +--antlr.InputBuffer

Direct Known Subclasses:

ByteBuffer, CharBuffer, DebuggingInputBuffer

public abstract class InputBuffer

extends Object

Untamed: 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:

antlr.CharQueue

Field Summary

protected int	markerOffset
protected int	nMarkers
protected int	numToConsume
protected CharQueue	queue

Constructor Summary

InputBuffer()
Enabled: Create an input buffer

Method Summary

void	commit() Enabled: 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() Enabled: Mark another character for deferred consumption
abstract void	fill(int amount) Enabled: Ensure that the input buffer is sufficiently full
String	getLAChars() Enabled:
String	getMarkedChars() Enabled:
boolean	isMarked() Enabled:
char	LA(int i) Enabled: Get a lookahead character
int	mark() Enabled: Return an integer marker that can be used to rewind the buffer to its current state.
void	rewind(int mark) Enabled: Rewind the character buffer to a marker.
protected void	syncConsume() Sync up deferred consumption

Methods inherited from class java.lang.Object

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

Field Detail

nMarkers

protected int nMarkers

markerOffset

protected int markerOffset

numToConsume

protected int numToConsume

queue

protected CharQueue queue

Constructor Detail

InputBuffer

public InputBuffer()

Enabled: Create an input buffer

Method Detail

commit

public void commit()

Enabled: 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()

Enabled: Mark another character for deferred consumption

fill

public abstract void fill(int amount)
                   throws CharStreamException

Enabled: Ensure that the input buffer is sufficiently full

CharStreamException

getLAChars

public String getLAChars()

Enabled:

getMarkedChars

public String getMarkedChars()

Enabled:

isMarked

public boolean isMarked()

Enabled:

LA

public char LA(int i)
        throws CharStreamException

Enabled: Get a lookahead character

CharStreamException

mark

public int mark()

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

rewind

public void rewind(int mark)

Enabled: Rewind the character buffer to a marker.

Parameters:

mark - Marker returned previously from mark()

syncConsume

protected void syncConsume()

Sync up deferred consumption