Package eu.bandm.tools.lexic

Class LookaheadTokenMultiplexer<K,D,T,L>

java.lang.Object

eu.bandm.tools.lexic.LookaheadTokenMultiplexer<K,D,T,L>

Type Parameters:

K - the type of keys

D - the type of source document identifiers

T - the type of token types

L - the type of lookahead data

All Implemented Interfaces:

LookaheadTokenSource<D,T,L>, Closeable, AutoCloseable, Supplier<Token<D,T>>

public class LookaheadTokenMultiplexer<K,D,T,L>
extends Object
implements LookaheadTokenSource<D,T,L>

A multiplexer between token source channels with internal lookahead buffer, selected by a key.

Lookahead data is transferred automatically between sources upon switching.

Constructor Summary

Constructors

Constructor	Description
LookaheadTokenMultiplexer(K key, LookaheadTokenSource<D,T,L> channel)	Creates a new instance with one entry.

Method Summary

Modifier and Type	Method	Description
Token<D,T>	get()
LookaheadTokenSource<D,T,L>	getCurrentChannel()	Returns the currently selected channel.
K	getCurrentKey()	Returns the key for the currently selected channel.
LookaheadTokenMultiplexer<K,D,T,L>	put(K key, LookaheadTokenSource<D,T,L> channel)	Adds an entry to this multiplexer.
L	relinquishLookahead()	Clear the internal lookahead buffer and return its contents.
void	select(K key)	Selects a channel by key.
void	takeOverLookahead(L lookaheadData)	Fill the internal lookahead buffer with data.

Methods inherited from class java.lang.Object

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

Methods inherited from interface eu.bandm.tools.lexic.LookaheadTokenSource

close, forgetLookahead, removeTypes, removeTypes

Constructor Details

LookaheadTokenMultiplexer

public LookaheadTokenMultiplexer(K key,
 LookaheadTokenSource<D,T,L> channel)

Creates a new instance with one entry.

The given channel is also initially selected.

Parameters:

key - the key for selecting the given channel

channel - the channel associated with the key

Method Details

put

public LookaheadTokenMultiplexer<K,D,T,L> put(K key,
 LookaheadTokenSource<D,T,L> channel)

Adds an entry to this multiplexer.

Keys cannot be reused; existing entries are immutable.

The currently selected channel is not changed.

Parameters:

key - the key for selecting the given channel

channel - the channel associated with the key

Returns:

this for convenient chained method calls

Throws:

NullPointerException - if key or channel is null

IllegalArgumentException - if key is already in use

getCurrentKey

public K getCurrentKey()

Returns the key for the currently selected channel.

Returns:

the key for the currently selected channel

getCurrentChannel

public LookaheadTokenSource<D,T,L> getCurrentChannel()

Returns the currently selected channel.

Returns:

the currently selected channel

select

public void select(K key)

Selects a channel by key.

If the newly selected channel is not the same as the previously selected one, LookaheadTokenSource.transferLookahead(eu.bandm.tools.lexic.LookaheadTokenSource<?, ?, ? extends L>, eu.bandm.tools.lexic.LookaheadTokenSource<?, ?, ? super L>) is called.

Parameters:

key - the key for the channel to select

Throws:

IllegalArgumentException - if there is no entry for the given key

See Also:

• LookaheadTokenSource.transferLookahead(eu.bandm.tools.lexic.LookaheadTokenSource<?, ?, ? extends L>, eu.bandm.tools.lexic.LookaheadTokenSource<?, ?, ? super L>)

get

public Token<D,T> get()

This method delegates to the currently selected channel.

Specified by:

get in interface Supplier<K>

relinquishLookahead

public L relinquishLookahead()

Clear the internal lookahead buffer and return its contents.

This method delegates to the currently selected channel.

Specified by:

relinquishLookahead in interface LookaheadTokenSource<K,D,T>

Returns:

the former contents of the internal lookahead buffer

takeOverLookahead

public void takeOverLookahead(L lookaheadData)

Fill the internal lookahead buffer with data.

The buffer must be empty before this method is invoked. After return, the given data will be consumed from the buffer before the usual input is considered.

This method delegates to the currently selected channel.

Specified by:

takeOverLookahead in interface LookaheadTokenSource<K,D,T>

Parameters:

lookaheadData - the lookahead data to fill in