Package nltk :: Package parse :: Module chart :: Class TopDownInitRule

type TopDownInitRule

   object --+        
            |        
   ChartRuleI --+    
                |    
AbstractChartRule --+
                    |
                   TopDownInitRule

Known Subclasses:

featurechart.FeatureTopDownInitRule

A rule licensing edges corresponding to the grammar productions for the grammar's start symbol. In particular, this rule specifies that:

[S → * α][0:i]

is licensed for each grammar production S → α, where S is the grammar's start symbol.

Instance Methods

[hide private]

iter of EdgeI

apply_iter(self, chart, grammar)
Returns: A generator that will add edges licensed by this rule and the given edges to the chart, one at a time.

source code

Inherited from AbstractChartRule: __str__, apply, apply_everywhere, apply_everywhere_iter

Class Variables

[hide private]

int NUM_EDGES = 0
The number of existing edges that this rule uses to license new edges.

Method Details

[hide private]

apply_iter(self, chart, grammar)

source code

Parameters:

edges - A set of existing edges. The number of edges that should be passed to apply is specified by the NUM_EDGES class variable.

Returns: iter of EdgeI

A generator that will add edges licensed by this rule and the given edges to the chart, one at a time. Each time the generator is resumed, it will either add a new edge and yield that edge; or return.

Overrides: ChartRuleI.apply_iter

(inherited documentation)