Actions associated with productions are not performed during parsing.
Rather these functions can be called during a post-processing pass of
the parse tree with the proctree
function.
The action code
is called with one argument named kids
which is a list of
right hand side elements. The value returned by the action code is
associated with the production it belongs to. When the production
is used in the right hand side of another production in the parse
tree, its value will be passed in as an elements of the kids
argument for that production's action code.
See the API reference for more details.
If action code is not specified for a production, the default
action is used. This action is simply return kids
, which
returns a list of the right hand side elements of the derivation.
Some productions in the grammar are generated internally and have
their own actions associated with them, as will be seen in the next
section.
See the PyGgy Home Page.