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class Predicate
module And
include NadicBool
def operator_symbol
:'&&'
end
def &(other)
case other
when Tautology then self
when Contradiction then other
when And then sexpr(dup + other[1..-1])
else dup << other
end
end
def and_split(attr_list)
# Say we are X = X1 & X2 & X3
# We will split each term: X = (X1 & Y1) & (X2 & Y2) & (X3 & Y3)
# ... such that Y1, Y2, and Y2 makes no reference to attr_list
# ... which is equivalent to (X1 & X2 & X3) & (Y1 & Y2 & Y3)
# ... hence P1 & P2, that we return
sexpr_body.inject([tautology, tautology]) do |(top,down),term|
p1, p2 = term.and_split(attr_list)
[top & p1, down & p2]
end
end
def attr_split
# Similar to and_split above, but the reasonning applies on
# attribute names this time.
sexpr_body.each_with_object({}) do |term, h|
term.attr_split.each_pair do |a,p|
h[a] = (h[a] || tautology) & p
end
end
end
def constant_variables
sexpr_body.inject([]) do |cvars,expr|
cvars | expr.constant_variables
end
end
def constants
sexpr_body.each_with_object({}) do |op, cs|
cs.merge!(op.constants){|k,v1,v2| v1 }
end
end
def evaluate(tuple)
sexpr_body.all?{|operand| operand.evaluate(tuple) }
end
end
end
Version data entries
14 entries across 14 versions & 1 rubygems