33 lines
847 B
Ruby
33 lines
847 B
Ruby
module UnitConversion
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UNIT_PARSING_REGEX = /^(?<value>(?:-?[0-9]+)?(?:\.?[0-9]*)?)\s*(?<unit>[a-z\/.\-()0-9]+)$/
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class UnparseableUnitError < StandardError
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end
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class UnknownUnitError < UnparseableUnitError
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end
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class << self
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def parse(unit_string)
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match = UNIT_PARSING_REGEX.match(unit_string.to_s.strip)
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if match && match[:value].present? && match[:unit].present?
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begin
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Unitwise(match[:value].to_f, match[:unit])
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rescue Unitwise::ExpressionError => err
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raise UnknownUnitError, err.message
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end
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else
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raise UnparseableUnitError, "'#{unit_string}' does not appear to be a valid measurement of the form <value> <units> (ie '5 cup' or '223 gram/cup')"
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end
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end
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def density?(unit)
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unit.compatible_with? Unitwise(1, 'g/ml')
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end
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end
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end
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