Class: LogicTools::NodeNary

Inherits:
Node
  • Object
show all
Extended by:
Forwardable
Includes:
Enumerable
Defined in:
lib/logic_tools/logictree.rb

Overview

Represents an operator node with multiple children.

Direct Known Subclasses

NodeAnd, NodeOr

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Node

#each_line, #each_maxterm, #each_minterm, #eql?, #getVariables, #hash, #inspect, #simplify, #size, #to_std_conjunctive, #to_std_disjunctive, #to_sum_product

Instance Attribute Details

#op ⇒ Object (readonly)

Returns the value of attribute op.



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# File 'lib/logic_tools/logictree.rb', line 365

def op
  @op
end

Class Method Details

.make(op, *children) ⇒ Object

Creates a node with operator op and children (factory method).



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# File 'lib/logic_tools/logictree.rb', line 385

def NodeNary.make(op,*children)
    case op
    when :or 
        return NodeOr.new(*children)
    when :and
        return NodeAnd.new(*children)
    else 
        raise ArgumentError.new("Not a valid operator: #{op}")
    end
end

Instance Method Details

#==(node) ⇒ Object

Compares with node.



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# File 'lib/logic_tools/logictree.rb', line 440

def ==(node) # :nodoc:
    return false unless node.is_a?(Node)
    return false unless self.op == node.op
    # There is no find_with_index!
    # return ! @children.find_with_index {|child,i| child != node[i] }
    @children.each_with_index do |child,i|
        return false if child != node[i]
    end
    return true
end

#distribute(dop, node) ⇒ Object

Creates a new tree where the current node is distributed over node

according to the +dop+ operator.



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# File 'lib/logic_tools/logictree.rb', line 549

def distribute(dop,node) # :nodoc:
    fop = dop == :and ? :or : :and
    # print "dop=#{dop} fop=#{fop} self.op=#{@op}\n"
    if (@op == dop) then
        # Self operator is dop: merge node in self
        return NodeNary.make(dop,*self,node).flatten
    else
        # self operator if fop
        if (node.op == fop) then
            # node operator is also fop: (a+b)(c+d) or ab+cd case
            nchildren = []
            self.each do |child0|
                node.each do |child1|
                    # print "child0=#{child0}, child1=#{child1}\n"
                    nchildren << 
                        NodeNary.make(dop, child0, child1).flatten
                    # print "nchildren=#{nchildren}\n"
                end
            end
            return NodeNary.make(fop,*nchildren).flatten
        else
            # node operator is not fop: (a+b)c or ab+c case
            nchildren = self.map do |child|
                NodeNary.make(dop,child,node).flatten
            end
            return NodeNary.make(fop,*nchildren).flatten
        end
    end
end

#each(&blk) ⇒ Object

Iterates over the children.



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# File 'lib/logic_tools/logictree.rb', line 401

def each(&blk) # :nodoc:
    @children.each(&blk)
    return self
end

#flatten ⇒ Object

Flatten ands, ors and nots.



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# File 'lib/logic_tools/logictree.rb', line 522

def flatten # :nodoc:
    return NodeNary.make(@op,*(@children.reduce([]) do |nchildren,child|
        if (child.op == self.op) then
            nchildren.push(*child)
        else
            nchildren << child
        end
    end)).reduce
end

#flatten_deep ⇒ Object

Creates a new tree where all the and, or and not operators

from the current node are flattened.

Default: simply duplicate.



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# File 'lib/logic_tools/logictree.rb', line 536

def flatten_deep # :nodoc:
    return NodeNary.make(@op,*(@children.reduce([]) do |nchildren,child|
        child = child.flatten_deep
        if (child.op == self.op) then
            nchildren.push(*child)
        else
            nchildren << child
        end
    end)).reduce
end

#getVariablesRecurse ⇒ Object

Gets the variables, recursively, without postprocessing.

Returns the variables into sets of arrays with possible doublon



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# File 'lib/logic_tools/logictree.rb', line 433

def getVariablesRecurse() # :nodoc:
    return @children.reduce([]) do |res,child|
        res.concat(child.getVariablesRecurse)
    end
end

#reduce ⇒ Object

Reduces a node: remove its redundancies using the absbortion rules.

--
TODO consider the X~X and X+~X cases.



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# File 'lib/logic_tools/logictree.rb', line 485

def reduce
    # The operator used for the factors
    fop = @op == :and ? :or : :and
    # Gather the terms converted to a sorted string for fast
    # comparison
    terms = @children.map do |child|
        if (child.op == fop) then
            [ child, child.sort.to_s ]
        else
            [ child, child.to_s ]
        end
    end
    nchildren = []
    # Keep only the terms that do not contain another one
    terms.each_with_index do |term0,i|
        skipped = false
        terms.each_with_index do |term1,j|
            next if (i==j) # Same term
            if (term0[1].include?(term1[1])) and term0[1]!=term1[1] then
                # term0 contains term1 but is different, skip it
                skipped = true
                break
            end
        end
        nchildren << term0[0] unless skipped # Term has not been skipped
    end
    # Avoid duplicates
    nchildren.uniq!
    # Generate the result
    if (nchildren.size == 1)
        return nchildren[0]
    else
        return NodeNary.make(@op,*nchildren)
    end
end

#sort ⇒ Object

Creates a new node whose childrens are sorted.



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# File 'lib/logic_tools/logictree.rb', line 407

def sort
    return NodeNary.make(@op,*@children.sort_by {|child| child.to_sym })
end

#to_sym ⇒ Object

Converts to a symbol.



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# File 'lib/logic_tools/logictree.rb', line 426

def to_sym # :nodoc:
    return @sym
end

#uniq(&blk) ⇒ Object

Creates a new node without duplicate in the children.



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# File 'lib/logic_tools/logictree.rb', line 412

def uniq(&blk)
    if blk then
        nchildren = @children.uniq(&blk)
    else
        nchildren = @children.uniq { |child| child.to_sym }
    end
    if nchildren.size == 1 then
        return nchildren[0]
    else
        return NodeNary.make(@op,*nchildren)
    end
end