Package td_parser
source code
Code and classes for top down recursive descent parser. Currently just
a recognizer is actually implemented.
>>> from td_parser import *
>>> demo(['John likes Mary'])
This will recognize 'John likes Mary' with the first default grammar
defined in the demo function at the bottom of the module
file.
>>> g = Grammar('s')
defines a grammar g with start symbol 's'
>>> g.add_production('s', ['np','vp'])
adds the rule s -> np vp.
>>> p = Parser(g)
creates a parser instance p with grammar g.
>>> p.trace()
>>> p.recognize_string('The boy likes the girl')
Turn verbose trace output on for p and recognize the
string 'The boy likes the girl.'
For more examples of all of the above see the demo
function in td_parser.td_parser.
>>> strings = ['John likes Mary', 'The boy likes the girl', 'Eat beans']
>>> demo(strings)
Run the demo with these 3 strings.
td_parser.td_parser includes a class for a top down
recursive descent parser, a class for context-free grammars, and parser
states. There are two grammars defined in the demo function, declared as
globals g1 and g2.