Rule

import mathy_core.rule

BaseRule¶

BaseRule(self, args, kwargs)

Basic rule class that visits a tree with a specified visit order.

apply_to¶

BaseRule.apply_to(
    self, 
    node: mathy_core.expressions.MathExpression, 
) -> 'ExpressionChangeRule'

Apply the rule transformation to the given node, and return a ExpressionChangeRule object that captures the input/output states for the change.

can_apply_to¶

BaseRule.can_apply_to(self, node: mathy_core.expressions.MathExpression) -> bool

User-specified function that returns True/False if a rule can be applied to a given node.

Performance Point

can_apply_to is called very frequently during normal operation and should be implemented as efficiently as possible.

code¶

Short code for debug rendering. Should be two letters.

find_node¶

BaseRule.find_node(
    self, 
    expression: mathy_core.expressions.MathExpression, 
) -> Optional[mathy_core.expressions.MathExpression]

Find the first node that can have this rule applied to it.

find_nodes¶

BaseRule.find_nodes(
    self, 
    expression: mathy_core.expressions.MathExpression, 
) -> List[mathy_core.expressions.MathExpression]

Find all nodes in an expression that can have this rule applied to them. Each node is marked with it's token index in the expression, according to the visit strategy, and stored as node.r_index starting with index 0

name¶

Readable rule name used for debug rendering and description outputs

ExpressionChangeRule¶

ExpressionChangeRule(
    self, 
    rule: mathy_core.rule.BaseRule, 
    node: Optional[mathy_core.expressions.MathExpression] = None, 
)

Object describing the change to an expression tree from a rule transformation

done¶

ExpressionChangeRule.done(
    self, 
    node: mathy_core.expressions.MathExpression, 
) -> 'ExpressionChangeRule'

Set the result of a change to the given node. Restore the parent if save_parent was called.

save_parent¶

ExpressionChangeRule.save_parent(
    self, 
    parent: Optional[mathy_core.expressions.MathExpression] = None, 
    side: Optional[Literal['left', 'right']] = None, 
) -> 'ExpressionChangeRule'

Note the parent of the node being modified, and set it as the parent of the rule output automatically.