|Modifier and Type||Method and Description|
Who's using this axe?
Is this a specialist axe?
Select a branch from a list of branches.
Was the previous selection ambiguous?
A specialist axe can consider every tree in the forest differently every time it is used. A non-specialist axe considers every tree at most once and returns all the trees that are selected.
java.util.List<Family> select(ParseTree tree, ForestNode forestNode, int count, java.util.List<Family> choices)
In an ambiguous forest, some nodes will have more than one possible choice. In any given tree, only one choice may be selected. This function is called to make the selection.
There will always be at least one element in the choices list when the method is called. The method must return at least one.
The first node in the list returned is the choice selected for the tree currently under construction. If only one choice is returned, the node becomes unambiguous on subsequent parses, the same selection will always be used. If additional choices are returned, they will be considered on subsequent parses. Note that if you want the selected choice to be considered on future parses, it must appear in the list twice. It is the only node that may appear twice.
tree- the parent node in the parse tree
forestNode- the forest node
count- the number of times node has occurred in this parse
choices- the possible paths
java.lang.NullPointerException- if null is returned
TreeWalkerException- if an invalid choice is made
This method asks if the previous selection was ambiguous. If the axe ever indicates that
an ambiguous selection was made, the resulting parse is considered ambiguous. For example, the
SequentialAxe always returns true because it treats all choices as equivalent.
PriorityAxe only considers a selection ambiguous if there wasn't a uniquely highest