Class: Metamorphosis::Engine

Inherits:
Object
  • Object
show all
Includes:
Singleton
Defined in:
lib/metamorphosis/engine.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Engine

Returns a new instance of Engine.



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# File 'lib/metamorphosis/engine.rb', line 15

def initialize
  reset!
end

Instance Attribute Details

#registry ⇒ Object (readonly)

Returns the value of attribute registry.



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# File 'lib/metamorphosis/engine.rb', line 7

def registry
  @registry
end

Instance Method Details

#common_unit_category(source, dest) ⇒ Object 



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# File 'lib/metamorphosis/engine.rb', line 24

def common_unit_category(source, dest)
  source_categories = @registry.unit_categories(source)
  dest_categories   = @registry.unit_categories(dest)

  category = (source_categories & dest_categories).first
end

#convert_to(dest_unit_name, source) ⇒ Object 



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# File 'lib/metamorphosis/engine.rb', line 31

def convert_to(dest_unit_name, source)
  return source if dest_unit_name.to_sym == source.unit_symbol

  exponent, dest_unit_symbol = @parser.parse(dest_unit_name)
  return unless @registry.include?(dest_unit_symbol)

  category = common_unit_category(source.unit_symbol, dest_unit_symbol)
  unless category
    raise IncompatibleUnitsError,
      "Cannot convert from #{source.unit_symbol} to #{dest_unit_symbol}"
  end

  value = to_base_value(category, source)

  from_base_value(category, dest_unit_symbol, value, exponent)
end

#from_base_value(category, dest_unit_symbol, value, exponent) ⇒ Object 



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# File 'lib/metamorphosis/engine.rb', line 48

def from_base_value(category, dest_unit_symbol, value, exponent)
  conversion_factor = @registry.conversion_factor(category, dest_unit_symbol)
  if conversion_factor.is_a?(Array)
    new_unit_value = conversion_factor[1].call(value)
  else
    new_unit_value = value / (exponent * conversion_factor)
  end
  UnitValue.new(dest_unit_symbol, new_unit_value)
end

#numeric_to_unit_value(numeric, unit_name) ⇒ Object 



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# File 'lib/metamorphosis/engine.rb', line 9

def numeric_to_unit_value(numeric, unit_name)
  exponent, unit_symbol = @parser.parse(unit_name)
  return nil unless @registry.include?(unit_symbol)
  UnitValue.new(unit_symbol, numeric, exponent)
end

#register_unit(category, symbols, value) ⇒ Object 



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# File 'lib/metamorphosis/engine.rb', line 67

def register_unit(category, symbols, value)
  value = value.is_a?(UnitValue) ? to_base_value(category, value) : value
  symbols = Array(symbols)
  symbols.each do |unit_symbol|
    @registry.register(category, unit_symbol, value)
  end
end

#reset! ⇒ Object 



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# File 'lib/metamorphosis/engine.rb', line 19

def reset!
  @registry = UnitRegistry.new
  @parser = PrefixParser.new(DEFAULT_PREFIXES, @registry)
end

#to_base_value(category, source_unit) ⇒ Object 



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# File 'lib/metamorphosis/engine.rb', line 58

def to_base_value(category, source_unit)
  conversion_factor = @registry.conversion_factor(category, source_unit.unit_symbol)
  if(conversion_factor.is_a?(Array))
    conversion_factor[0].call(source_unit.value) * source_unit.exponent
  else
    source_unit.to_f * conversion_factor
  end
end