Package nltk :: Module cfg :: Class Grammar

Class Grammar

object --+
         |
        Grammar

Known Subclasses:

WeightedGrammar

A context-free grammar. A Grammar consists of a start state and a set of productions. The set of terminals and nonterminals is implicitly specified by the productions.

If you need efficient key-based access to productions, you can use a subclass to implement it.

Instance Methods

[hide private]

__init__(self, start, productions, lexicon=None)
Create a new context-free grammar, from the given start state and set of Productions. source code

start(self)

source code

productions(self, lhs=None, rhs=None)

source code

lexicon(self)

source code

check_coverage(self, tokens)
Check whether the grammar rules cover the given list of tokens.

source code

covers(self, tokens)
Check whether the grammar rules cover the given list of tokens.

source code

__repr__(self)
repr(x)

source code

__str__(self)
str(x)

source code

Inherited from object: __delattr__, __getattribute__, __hash__, __new__, __reduce__, __reduce_ex__, __setattr__

Properties

[hide private]

Inherited from object: __class__

Method Details

[hide private]

init(self, start, productions, lexicon=None)
(Constructor)

source code

Create a new context-free grammar, from the given start state and set of Productions.

Parameters:

start (Nonterminal) - The start symbol
productions (list of Production) - The list of productions that defines the grammar

Overrides: object.__init__

check_coverage(self, tokens)

source code

Check whether the grammar rules cover the given list of tokens. If not, then raise an exception.

covers(self, tokens)

source code

Check whether the grammar rules cover the given list of tokens.

Parameters:

tokens (a list of string objects.) - the given list of tokens.

Returns:

True/False

repr(self)
(Representation operator)

source code

repr(x)

Overrides: object.__repr__: (inherited documentation)

str(self)
(Informal representation operator)

source code

str(x)

Overrides: object.__str__: (inherited documentation)

Class Grammar

__init__(self, start, productions, lexicon=None) (Constructor)

check_coverage(self, tokens)

covers(self, tokens)

__repr__(self) (Representation operator)

__str__(self) (Informal representation operator)

init(self, start, productions, lexicon=None)
(Constructor)

repr(self)
(Representation operator)

str(self)
(Informal representation operator)