Class: ConstraintSolver::OneOfEqualsConstraint

Inherits:
AbstractConstraint show all
Defined in:
lib/OneOfEqualsConstraint.rb

Overview

Represents a one-of-equals constraint.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(variables, value, violationCost = 1) ⇒ OneOfEqualsConstraint

Initialises a new one-of-equals constraint. The arguments are the list of variables involved in the constraint and the value at least one of the variables should be equal to. Optionally, a cost for violating the constraint can be specified.



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# File 'lib/OneOfEqualsConstraint.rb', line 14

def initialize(variables, value, violationCost=1)
    if variables.empty?
	raise ArgumentError, "List of variables must not be empty!"
    end
    @variables = variables
    @value = value
    @violationCost = violationCost
end

Instance Attribute Details

#value ⇒ Object (readonly)

Returns the value of attribute value.



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# File 'lib/OneOfEqualsConstraint.rb', line 9

def value
  @value
end

#variables ⇒ Object (readonly)

Returns the value of attribute variables.



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# File 'lib/OneOfEqualsConstraint.rb', line 9

def variables
  @variables
end

#violationCost ⇒ Object (readonly)

Returns the value of attribute violationCost.



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# File 'lib/OneOfEqualsConstraint.rb', line 9

def violationCost
  @violationCost
end

Instance Method Details

#==(constraint) ⇒ Object 



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# File 'lib/OneOfEqualsConstraint.rb', line 50

def ==(constraint)
    return false unless constraint.kind_of?(OneOfEqualsConstraint)
    (@variables == constraint.variables) and (@value == constraint.value) and
	(@violationCost == constraint.violationCost)
end

#allAssigned? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/OneOfEqualsConstraint.rb', line 31

def allAssigned?
    @variables.each { |var|
	return false if not var.assigned?
    }
    return true
end

#each ⇒ Object 



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# File 'lib/OneOfEqualsConstraint.rb', line 56

def each
    @variables.each { |var|
	yield var
    }
end

#holds? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/OneOfEqualsConstraint.rb', line 23

def holds?
    if not allAssigned? or not @variables.find { |var| var.value == @value }.nil?
	return true
    else
	return false
    end
end

#include?(variable) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/OneOfEqualsConstraint.rb', line 38

def include?(variable)
    @variables.include?(variable)
end

#revise ⇒ Object 



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# File 'lib/OneOfEqualsConstraint.rb', line 62

def revise
    checks = 0
    revisedVariables = []
    wipeout = false
    if @variables.find_all { |var| var.assigned? and not var.value == @value }.size == @variables.size - 1
	unassigned = @variables.find { |var| not var.assigned? }
	pruneList = unassigned.domain.values - [ @value ]
	if not pruneList.empty?
	    begin
		unassigned.domain.prune(pruneList)
	    rescue DomainWipeoutException
		wipeout = true
	    end
	    revisedVariables << unassigned
	end
    end
    return revisedVariables, checks, wipeout
end

#to_s ⇒ Object 



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# File 'lib/OneOfEqualsConstraint.rb', line 42

def to_s
    @variables.collect { |var| var.name }.join(" != ")
end

#to_s_full ⇒ Object 



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# File 'lib/OneOfEqualsConstraint.rb', line 46

def to_s_full
    @variables.collect { |var| var.to_s }.join(" != ")
end