Class: Unit::System

Inherits:

Object

• Object
• Unit::System

show all

Defined in:

lib/unit/system.rb

Constant Summary

Instance Attribute Summary (collapse)

• - (Object) factor readonly

  Returns the value of attribute factor.

• - (Object) factor_symbol readonly

  Returns the value of attribute factor_symbol.

• - (Object) factor_value readonly

  Returns the value of attribute factor_value.

• - (Object) name readonly

  Returns the value of attribute name.

• - (Object) unit readonly

  Returns the value of attribute unit.

• - (Object) unit_symbol readonly

  Returns the value of attribute unit_symbol.

Instance Method Summary (collapse)

• - (System) initialize(name) {|_self| ... } constructor

  A new instance of System.

• - (Object) load(input)
• - (Object) parse_unit(expr)
• - (Object) validate_unit(units)

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# File 'lib/unit/system.rb', line 8

def initialize(name)
  @name = name
  @unit = {}
  @unit_symbol = {}

  # one is internal trivial factor
  @factor = {:one => {:symbol => 'one', :value => 1} }
  @factor_symbol = {'one' => :one}
  @factor_value = {1 => :one}

  @loaded_systems = []
  @loaded_filenames = []

  yield(self) if block_given?
end

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# File 'lib/unit/system.rb', line 6

def factor
  @factor
end

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# File 'lib/unit/system.rb', line 6

def factor_symbol
  @factor_symbol
end

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# File 'lib/unit/system.rb', line 6

def factor_value
  @factor_value
end

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# File 'lib/unit/system.rb', line 6

def name
  @name
end

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# File 'lib/unit/system.rb', line 6

def unit
  @unit
end

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# File 'lib/unit/system.rb', line 6

def unit_symbol
  @unit_symbol
end

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# File 'lib/unit/system.rb', line 24

def load(input)
  case input
  when Hash
    data = input
  when IO
    data = YAML.load(input.read)
  when String
    if File.exist?(input)
      return if @loaded_filenames.include?(input)
      data = YAML.load_file(input)
      @loaded_filenames << input
    else
      load(input.to_sym)
      return
    end
  when Symbol
    return if @loaded_systems.include?(input)
    data = YAML.load_file(File.join(File.dirname(__FILE__), 'systems', "#{input}.yml"))
    @loaded_systems << input
  end

  load_factors(data['factors']) if data['factors']
  load_units(data['units']) if data['units']

  @unit.each {|name, unit| validate_unit(unit[:def]) }

  true
end

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# File 'lib/unit/system.rb', line 63

def parse_unit(expr)
  stack, result, implicit_mul = [], [], false
  expr.to_s.scan(TOKENIZER).each do |tok|
    if tok == '('
      stack << '('
      implicit_mul = false
    elsif tok == ')'
      compute(result, stack.pop) while !stack.empty? && stack.last != '('
      raise(SyntaxError, 'Unexpected token )') if stack.empty?
      stack.pop
      implicit_mul = true
    elsif OPERATOR.key?(tok)
      compute(result, stack.pop) while !stack.empty? && stack.last != '(' && OPERATOR[stack.last][1] >= OPERATOR[tok][1]
      stack << OPERATOR[tok][0]
      implicit_mul = false
    else
      val = case tok
            when REAL   then [[:one, tok.to_f, 1]]
            when DEC    then [[:one, tok.to_i, 1]]
            when SYMBOL then symbol_to_unit(tok)
            end
      stack << '*' if implicit_mul
      implicit_mul = true
      result << val
    end
  end
  compute(result, stack.pop) while !stack.empty?
  result.last
end

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# File 'lib/unit/system.rb', line 53

def validate_unit(units)
  units.each do |factor, unit, exp|
    #raise TypeError, 'Factor must be symbol' if !(Symbol === factor)
    #raise TypeError, 'Unit must be symbol' if !(Numeric === unit || Symbol === unit)
    #raise TypeError, 'Exponent must be numeric' if !(Numeric === exp)
    raise TypeError, "Undefined factor #{factor}" if !@factor[factor]
    raise TypeError, "Undefined unit #{unit}" if !(Numeric === unit || @unit[unit])
  end
end