Class: LogicTools::NodeAnd

Inherits:
NodeNary show all
Defined in:
lib/logic_tools/logictree.rb

Overview

Represents an AND node

Instance Attribute Summary

Attributes inherited from NodeNary

#op

Instance Method Summary collapse

Methods inherited from NodeNary

#==, #add, #cover?, #distribute, #each, #flatten, #flatten_deep, #get_variablesRecurse, #include?, #is_parent?, make, #reduce, #sort, #to_sym, #uniq

Methods inherited from Node

#cover?, #distribute, #each, #each_line, #each_maxterm, #each_minterm, #eql?, #flatten, #flatten_deep, #get_variables, #hash, #include?, #inspect, #is_parent?, #op, #reduce, #simplify, #size, #to_cover, #to_std_conjunctive, #to_std_disjunctive, #to_sym

Constructor Details

#initialize(*children) ⇒ NodeAnd

Creates a new AND node with children.



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# File 'lib/logic_tools/logictree.rb', line 739

def initialize(*children)
    super(:and,*children)
end

Instance Method Details

#dup ⇒ Object

Duplicates the node.



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# File 'lib/logic_tools/logictree.rb', line 744

def dup # :nodoc:
    return NodeAnd.new(*@children.map(&:dup))
end

#eval ⇒ Object

Computes the value of the node.



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# File 'lib/logic_tools/logictree.rb', line 749

def eval()
    return !@children.any? {|child| child.eval() == false }
end

#to_s ⇒ Object

Convert to a string.



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# File 'lib/logic_tools/logictree.rb', line 785

def to_s # :nodoc:
    return @str if @str
    @str = ""
    # Convert the children to a string
    @children.each do |child|
        if (child.op == :or) then
            # Yes, need parenthesis
            @str << ( "(" + child.to_s + ")" )
        else
            @str << child.to_s
        end
    end
    return @str
end

#to_sum_product(flattened = false) ⇒ Object

Creates a sum fo product from the tree rooted by current node.

Argument +flattened+ tells if the tree is already flattend



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# File 'lib/logic_tools/logictree.rb', line 756

def to_sum_product(flattened = false) # :nodoc:
    # Flatten if required
    node = flattened ? self : self.flatten_deep
    return node unless node.is_parent?
    # Convert each child to sum of product
    nchildren = node.map {|child| child.to_sum_product(true) }
    # Distribute
    while(nchildren.size>1)
        # print "nchildren=#{nchildren}\n"
        dist = []
        nchildren.each_slice(2) do |left,right|
            if right then
                dist << (left.op == :or ? left.distribute(:and,right) :
                                          right.distribute(:and,left))
            else
                dist << left
            end
        end
        nchildren = dist
    end
    # Generate the or
    if (nchildren.size > 1)
        return NodeOr.new(*nchildren)
    else
        return nchildren[0]
    end
end