Class: Computable

Inherits:
Object
  • Object
show all
Defined in:
lib/computable.rb,
lib/computable/version.rb

Defined Under Namespace

Classes: Error, InvalidFormat, RecursionDetected, UndefinedValue, Variable

Constant Summary collapse

Unknown =

This is a special value to mark a variable to be computed.

Object.new
VERSION = 
"0.1.0"
@@debug = 
false

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Computable

Returns a new instance of Computable.



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# File 'lib/computable.rb', line 122

def initialize
  @variables = {}
  @caller = nil
end

Class Method Details

.calc_value(name, format = nil, params = {}, &block) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/computable.rb', line 134

def self.calc_value name, format=nil, params={}, &block
  freeze = params.delete(:freeze){ true }
  raise ArgumentError, "invalid params #{params.inspect}" unless params.empty?

  calc_method_id = "calc_#{name}".intern
  define_method(calc_method_id, &block)

  calc_method2_id = "calc_#{name}_with_tracking".intern
  define_method(calc_method2_id) do |v|
    begin
      v.value_calced = true
      @caller, old_caller = v, @caller
      begin
        puts "do calc #{v.inspect}" if @@debug
        res = send(calc_method_id)
        Computable.verify_format(name, res, format)
        res.freeze if freeze
        res
      ensure
        @caller = old_caller
      end
    end
  end

  define_method("#{name}=") do |value|
    Computable.verify_format(name, value, format)
    v = @variables[name]
    puts "set #{name}: #{value.inspect} #{v.inspect}" if @@debug
    v = @variables[name] = Variable.new(name, method(calc_method2_id)) unless v

    unless v.value == value
      v.expire_value
      v.expired_from.clear
      v.used_for.clear
      value.freeze if freeze
      v.value = value
    end
    v.value_calced = false
  end

  define_method(name) do
    v = @variables[name]
    puts "called #{name} #{v.inspect}" if @@debug
    v = @variables[name] = Variable.new(name, method(calc_method2_id)) unless v

    if @caller
      v2 = v.used_for[@caller.name]
      if v2
        if v.value==Unknown && v2.value==Unknown && v.value_calced && v2.value_calced
          raise RecursionDetected, "#{v2.name} depends on #{name}, but #{name} could not be computed without #{v2.name}"
        end
      else
        v.used_for[@caller.name] = @caller
      end
    end

    v.recalc_value

    v.value = v.calc! if v.value==Unknown
    v.value
  end
end

.computable_debug ⇒ Object 



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# File 'lib/computable.rb', line 86

def self.computable_debug
  @@debug
end

.computable_debug=(v) ⇒ Object 



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# File 'lib/computable.rb', line 83

def self.computable_debug=(v)
  @@debug = v
end

.input_value(name, format = nil, params = {}) ⇒ Object 



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# File 'lib/computable.rb', line 197

def self.input_value name, format=nil, params={}
  calc_value name, format, params do
    raise UndefinedValue, "input variable '#{name}' is not assigned"
  end
end

.verify_format(name, value, format) ⇒ Object 



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# File 'lib/computable.rb', line 128

def self.verify_format(name, value, format)
  if format && value!=Unknown && !(format === value)
    raise InvalidFormat, "variable '#{name}': value #{value.inspect} is not in format #{format.inspect}"
  end
end

Instance Method Details

#computable_display_dot(params = {}) ⇒ Object 



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# File 'lib/computable.rb', line 90

def computable_display_dot(params={})
  IO.popen("dot -Tpng | display -", "w") do |fd|
    fd.puts computable_to_dot(params)
  end
end

#computable_to_dot(params = {}) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/computable.rb', line 96

def computable_to_dot(params={})
  rankdir = params.delete(:rankdir){ "TB" }
  multiline = params.delete(:multiline){ true }
  raise ArgumentError, "invalid params #{params.inspect}" unless params.empty?

  dot = "digraph #{self.class.name.inspect} {\n"
  dot << "graph [ dpi = 45, rankdir=#{rankdir} ];\n"
  @variables.each do |name, v|
    col = case
      when !v.value_calced then "color = red,"
      when !v.used_for.empty? then "color = green,"
      else "color = blue,"
    end
    label = if multiline
      "#{name.to_s.gsub("_","\n")}\n(#{v.count})"
    else
      "#{name.to_s} (#{v.count})"
    end
    dot << "#{name.to_s.inspect} [#{col} label=#{label.inspect}];\n"
    v.used_for.each do |name2, v2|
      dot << "#{name.to_s.inspect} -> #{name2.to_s.inspect};\n"
    end
  end
  dot << "}\n"
end