Class: PubGrub::PartialSolution

Inherits:
Object
  • Object
show all
Defined in:
lib/pub_grub/partial_solution.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ PartialSolution

Returns a new instance of PartialSolution.



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# File 'lib/pub_grub/partial_solution.rb', line 9

def initialize
  reset!

  @attempted_solutions = 1
  @backtracking = false
end

Instance Attribute Details

#assignments ⇒ Object (readonly)

Returns the value of attribute assignments.



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# File 'lib/pub_grub/partial_solution.rb', line 6

def assignments
  @assignments
end

#attempted_solutions ⇒ Object (readonly)

Returns the value of attribute attempted_solutions.



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# File 'lib/pub_grub/partial_solution.rb', line 7

def attempted_solutions
  @attempted_solutions
end

#decisions ⇒ Object (readonly)

Returns the value of attribute decisions.



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# File 'lib/pub_grub/partial_solution.rb', line 6

def decisions
  @decisions
end

Instance Method Details

#backtrack(previous_level) ⇒ Object 



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# File 'lib/pub_grub/partial_solution.rb', line 63

def backtrack(previous_level)
  @backtracking = true

  new_assignments = assignments.select do |assignment|
    assignment.decision_level <= previous_level
  end

  new_decisions = Hash[decisions.first(previous_level)]

  reset!

  @decisions = new_decisions

  new_assignments.each do |assignment|
    add_assignment(assignment)
  end
end

#decide(package, version) ⇒ Object 



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# File 'lib/pub_grub/partial_solution.rb', line 54

def decide(package, version)
  @attempted_solutions += 1 if @backtracking
  @backtracking = false;

  decisions[package] = version
  assignment = Assignment.decision(package, version, decision_level, assignments.length)
  add_assignment(assignment)
end

#decision_level ⇒ Object 



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# File 'lib/pub_grub/partial_solution.rb', line 16

def decision_level
  @decisions.length
end

#derive(term, cause) ⇒ Object 



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# File 'lib/pub_grub/partial_solution.rb', line 32

def derive(term, cause)
  add_assignment(Assignment.new(term, cause, decision_level, assignments.length))
end

#relation(term) ⇒ Object 



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# File 'lib/pub_grub/partial_solution.rb', line 20

def relation(term)
  package = term.package
  return :overlap if !@terms.key?(package)

  @relation_cache[package][term] ||=
    @terms[package].relation(term)
end

#satisfier(term) ⇒ Object 



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# File 'lib/pub_grub/partial_solution.rb', line 36

def satisfier(term)
  assignment =
    @assignments_by[term.package].bsearch do |assignment|
      @cumulative_assignments[assignment].satisfies?(term)
    end

  assignment || raise("#{term} unsatisfied")
end

#satisfies?(term) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/pub_grub/partial_solution.rb', line 28

def satisfies?(term)
  relation(term) == :subset
end

#unsatisfied ⇒ Object

A list of unsatisfied terms



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# File 'lib/pub_grub/partial_solution.rb', line 46

def unsatisfied
  @required.reject do |package|
    @decisions.key?(package)
  end.map do |package|
    @terms[package]
  end
end