org.antlr.runtime.tree
Class RewriteRuleElementStream

java.lang.Object
  org.antlr.runtime.tree.RewriteRuleElementStream

Direct Known Subclasses:

RewriteRuleSubtreeStream, RewriteRuleTokenStream

public abstract class RewriteRuleElementStream
extends java.lang.Object

A generic list of elements tracked in an alternative to be used in a -> rewrite rule. We need to subclass to fill in the next() method, which returns either an AST node wrapped around a token payload or an existing subtree. Once you start next()ing, do not try to add more elements. It will break the cursor tracking I believe.

See Also:

RewriteRuleSubtreeStream, TODO: add mechanism to detect/puke on modification after reading from stream

Field Summary

protected TreeAdaptor	adaptor
protected int	cursor Cursor 0..n-1.
protected java.lang.String	elementDescription The element or stream description; usually has name of the token or rule reference that this list tracks.
protected java.util.List	elements The list of tokens or subtrees we are tracking
protected java.lang.Object	singleElement Track single elements w/o creating a list.

Constructor Summary

RewriteRuleElementStream(TreeAdaptor adaptor, java.lang.String elementDescription)

RewriteRuleElementStream(TreeAdaptor adaptor, java.lang.String elementDescription, java.util.List elements)
Create a stream, but feed off an existing list

RewriteRuleElementStream(TreeAdaptor adaptor, java.lang.String elementDescription, java.lang.Object oneElement)
Create a stream with one element

Method Summary

protected java.lang.Object	_next() do the work of getting the next element, making sure that it's a tree node or subtree.
void	add(java.lang.Object el)
protected abstract java.lang.Object	dup(java.lang.Object el) When constructing trees, sometimes we need to dup a token or AST subtree.
java.lang.String	getDescription()
boolean	hasNext()
java.lang.Object	next() Return the next element in the stream.
void	reset() Reset the condition of this stream so that it appears we have not consumed any of its elements.
int	size()
protected java.lang.Object	toTree(java.lang.Object el) Ensure stream emits trees; tokens must be converted to AST nodes.

Methods inherited from class java.lang.Object

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

Field Detail

cursor

protected int cursor

Cursor 0..n-1. If singleElement!=null, cursor is 0 until you next(), which bumps it to 1 meaning no more elements.

singleElement

protected java.lang.Object singleElement

Track single elements w/o creating a list. Upon 2nd add, alloc list

elements

protected java.util.List elements

The list of tokens or subtrees we are tracking

elementDescription

protected java.lang.String elementDescription

The element or stream description; usually has name of the token or rule reference that this list tracks. Can include rulename too, but the exception would track that info.

adaptor

protected TreeAdaptor adaptor

Constructor Detail

RewriteRuleElementStream

public RewriteRuleElementStream(TreeAdaptor adaptor,
                                java.lang.String elementDescription)

RewriteRuleElementStream

public RewriteRuleElementStream(TreeAdaptor adaptor,
                                java.lang.String elementDescription,
                                java.lang.Object oneElement)

Create a stream with one element

RewriteRuleElementStream

public RewriteRuleElementStream(TreeAdaptor adaptor,
                                java.lang.String elementDescription,
                                java.util.List elements)

Create a stream, but feed off an existing list

Method Detail

reset

public void reset()

Reset the condition of this stream so that it appears we have not consumed any of its elements. Elements themselves are untouched.

add

public void add(java.lang.Object el)

next

public java.lang.Object next()

Return the next element in the stream. If out of elements, throw an exception unless size()==1. If size is 1, then return elements[0]. Return a duplicate node/subtree if stream is out of elements and size==1.

_next

protected java.lang.Object _next()

do the work of getting the next element, making sure that it's a tree node or subtree. Deal with the optimization of single- element list versus list of size > 1. Throw an exception if the stream is empty or we're out of elements and size>1. protected so you can override in a subclass if necessary.

dup

protected abstract java.lang.Object dup(java.lang.Object el)

When constructing trees, sometimes we need to dup a token or AST subtree. Dup'ing a token means just creating another AST node around it. For trees, you must call the adaptor.dupTree().

toTree

protected java.lang.Object toTree(java.lang.Object el)

Ensure stream emits trees; tokens must be converted to AST nodes. AST nodes can be passed through unmolested.

hasNext

public boolean hasNext()

size

public int size()

getDescription

public java.lang.String getDescription()