org.nineml.coffeegrinder.parser

Class ParseForest

java.lang.Object

org.nineml.coffeegrinder.parser.ParseForest

Direct Known Subclasses:

ParseForestGLL

public class ParseForest
extends java.lang.Object

An SPPF is a shared packed parse forest.

The SPPF is a graph representation of all the (possibly infinite) parses that can be used to recognize the input sequence as a sentence in the grammar.

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	logcategory

Constructor Summary

Constructors

Constructor and Description
ParseForest(ParserOptions options)

Method Summary

Modifier and Type	Method and Description
java.util.List<ForestNode>	getAmbiguousNodes()
java.util.List<ForestNode>	getNodes() Get the nodes in the graph.
ParserOptions	getOptions() Get the options for this forest.
int	getParseTreeCount() How many parse trees are there in this forest?
ForestNode	getRoot()
boolean	isAmbiguous() Is the grammar represented by this graph ambiguous?
boolean	isInfinitelyAmbiguous() Is the grammar represented by this graph infinitely ambiguous?
java.lang.String	serialize() Serialize the graph as XML.
void	serialize(java.io.PrintStream stream) Serialize the graph as XML.
void	serialize(java.lang.String filename) Serialize the graph as XML.
int	size() How big is the graph?

Methods inherited from class java.lang.Object

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

Field Detail

logcategory

public static final java.lang.String logcategory

See Also:

Constant Field Values

Constructor Detail

ParseForest

public ParseForest(ParserOptions options)

Method Detail

isAmbiguous

public boolean isAmbiguous()

Is the grammar represented by this graph ambiguous?

A grammar is ambiguous if there are more than two parses that will recognize the input.

Returns:

true if the grammar is ambiguous

isInfinitelyAmbiguous

public boolean isInfinitelyAmbiguous()

Is the grammar represented by this graph infinitely ambiguous?

If the answer is "true", then the graph is infinitely ambiguous. If the graph is ambiguous and the anwer is "false", then all that can be said is the single parse explored to check ambiguity did not encounter infinite ambiguity. It is not an assertion that no unexplored part of the graph contains a loop.

Returns:

true if the parse forest is known to be infinitely ambiguous

getParseTreeCount

public int getParseTreeCount()

How many parse trees are there in this forest?

In an infinitely ambiguous graph, there are an infinite number of parse trees. However, CoffeeGrinder will never follow the same edge twice when constructing a tree, it won't loop. So the number of available trees is always a finite number.

Returns:

the parse tree count

getAmbiguousNodes

public java.util.List<ForestNode> getAmbiguousNodes()

size

public int size()

How big is the graph?

Returns:

the number of nodes in the graph

getNodes

public java.util.List<ForestNode> getNodes()

Get the nodes in the graph.

Returns:

the nodes in the graph.

getRoot

public ForestNode getRoot()

getOptions

public ParserOptions getOptions()

Get the options for this forest.

Returns:

the options.

serialize

public java.lang.String serialize()

Serialize the graph as XML.

Returns:

an XML serialization as a string

serialize

public void serialize(java.io.PrintStream stream)

Serialize the graph as XML.

Parameters:

stream - the stream on which to write the XML serialization

serialize

public void serialize(java.lang.String filename)

Serialize the graph as XML.

This method attempts to write the XML to a file.

Parameters:

filename - the name of the file

Throws:

ForestException - if a error occurs attempt to write to the file