antlr

Class InputBuffer

public abstract class InputBuffer extends 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

Field Summary
protected intmarkerOffset
protected intnMarkers
protected intnumToConsume
protected CharQueuequeue
Constructor Summary
InputBuffer()
Create an input buffer
Method Summary
voidcommit()
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.
voidconsume()
Mark another character for deferred consumption
abstract voidfill(int amount)
Ensure that the input buffer is sufficiently full
StringgetLAChars()
StringgetMarkedChars()
booleanisMarked()
charLA(int i)
Get a lookahead character
intmark()
Return an integer marker that can be used to rewind the buffer to its current state.
voidreset()
Reset the input buffer
voidrewind(int mark)
Rewind the character buffer to a marker.
protected voidsyncConsume()
Sync up deferred consumption

Field Detail

markerOffset

protected int markerOffset

nMarkers

protected int nMarkers

numToConsume

protected int numToConsume

queue

protected CharQueue queue

Constructor Detail

InputBuffer

public InputBuffer()
Create an input buffer

Method Detail

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)
Ensure that the input buffer is sufficiently full

getLAChars

public String getLAChars()

getMarkedChars

public String getMarkedChars()

isMarked

public boolean isMarked()

LA

public char LA(int i)
Get a lookahead character

mark

public int mark()
Return an integer marker that can be used to rewind the buffer to its current state.

reset

public void reset()
Reset the input buffer

rewind

public void rewind(int mark)
Rewind the character buffer to a marker.

Parameters: mark Marker returned previously from mark()

syncConsume

protected void syncConsume()
Sync up deferred consumption