yeanpypa.Rule

Module yeanpypa :: Class Rule

[show private | hide private]

Class Rule

Known Subclasses:: AndRule, AnyOf, CallbackParser, Combine, IgnoreWhite, Literal, MatchWhite, NoneOf, OneOrMore, Optional, OrRule, ZeroOrMore

The basic entity of a grammar: the rule. This class doesn't provide any parsing functionality on it's own. It merely provides some basic functions shared by all Rule classes.

Method Summary
	`__add__(self, second_rule)` Define an operator to concat two rules.
	`__or__(self, second_rule)` Define an operator to concat two rules via OR.
	`callAction(self, param)` Call the action attached to this rule.
	`hide(self)` Tell this rule to not produce any token output.
	`match(input_reader)` Match the given rule in the string from the given position on.
	`returnToken(self, token)` Helper function encapsulating the hide()-functionality.
	`setAction(self, action)` Set the action to execute on a rule match.

Class Variable Summary
`NoneType`	`action` = None
`bool`	`hide_token` = `False`

Method Details

add(self, second_rule)
(Addition operator)

Define an operator to concat two rules. The expressivness of the 'pseudo-language' defined by the framework heavily relies on operator overloading. The +-operator serves as a 'followed by' expression.

Parameters:: second_rule - The right operand of the +-operator which follows this object in grammar terms.
(type=Rule @return An AndRule-object connecting these two rule appropriately.)

or(self, second_rule)
(Or operator)

Define an operator to concat two rules via OR. The expressivness of the 'pseudo-language' defined by the framework heavily relies on operator overloading. The |-operator serves as a 'OR' expression, defining two alternative matches.

Parameters:: second_rule - The right operand of the +-operator which follows this object in grammar terms.
(type=Rule @return An OrRule-object connecting these two rule appropriately.)

callAction(self, param)

Call the action attached to this rule. The given parameter is passed to the action.

Parameters:: param - The parameter (token list) to pass to the action.
(type=list)

hide(self)

Tell this rule to not produce any token output. The rule matches its token as normal but does not return any of them

@return self

match(input_reader)

Match the given rule in the string from the given position on.

Parameters:: input_reader - The InputReader to read the input from.
(type=InputReader)

Returns:: a list of token the rule matched.

returnToken(self, token)

Helper function encapsulating the hide()-functionality. This method returns the token if self.hide is False and None otherwise.

Parameters:: token - The toden to return

Returns:: token if self.hide==False, None otherwise

setAction(self, action)

Set the action to execute on a rule match. Action may be any callable that takes a one parameter. The parameter is a list of token the rule matched. The action may manipulate the token returned by returning a different token list.

Parameters:: action - The callable to execute if the rule matched.
(type=Callable)

Returns:: a reference to the rule itself

Class Variable Details

action

Type:: NoneType
Value:: None

hide_token

Type:: bool
Value:: False

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