Class: Unit::System

Inherits:
Object
  • Object
show all
Defined in:
lib/unit/system.rb

Constant Summary collapse

SI = 
new('SI') do |system|
  system.load(:si)
  system.load(:binary)
  system.load(:degree)
  system.load(:time)
end

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(name) {|_self| ... } ⇒ System

Returns a new instance of System.

Yields:

  • (_self)

Yield Parameters:

  • _self (Unit::System) —

    the object that the method was called on



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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}

  yield(self) if block_given?
end

Instance Attribute Details

#factor ⇒ Object (readonly)

Returns the value of attribute factor.



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

def factor
  @factor
end

#factor_symbol ⇒ Object (readonly)

Returns the value of attribute factor_symbol.



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

def factor_symbol
  @factor_symbol
end

#factor_value ⇒ Object (readonly)

Returns the value of attribute factor_value.



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

def factor_value
  @factor_value
end

#name ⇒ Object (readonly)

Returns the value of attribute name.



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

def name
  @name
end

#unit ⇒ Object (readonly)

Returns the value of attribute unit.



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

def unit
  @unit
end

#unit_symbol ⇒ Object (readonly)

Returns the value of attribute unit_symbol.



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

def unit_symbol
  @unit_symbol
end

Instance Method Details

#load(input) ⇒ Object 



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# File 'lib/unit/system.rb', line 21

def load(input)
  case input
  when Hash
    raise "Invalid hash format to load system" unless (input["units"] && input["units"].first.last['def']) || input.first.last['def']
    data = input['units'] || input
  when IO
    data = YAML.load(input.read)
  when String
    if File.exist?(input)
      data = YAML.load_file(input)
    else
      data = YAML.load_file(File.join(File.dirname(__FILE__), 'systems', "#{input}.yml"))
    end
  when Symbol
    data = YAML.load_file(File.join(File.dirname(__FILE__), 'systems', "#{input}.yml"))
  end

  (data['factors'] || {}).each do |name, factor|
    name = name.to_sym
    symbols = [factor['sym'] || []].flatten
    factor['def'] =~ /^(\d+)\^(-?\d+)$/
    base = $1.to_i
    exp = $2.to_i
    value = base ** exp
    $stderr.puts "Factor #{name} already defined" if @factor[name]
    @factor[name] = { :symbol => symbols.first, :value => value }
    symbols.each do |sym|
      $stderr.puts "Factor symbol #{sym} for #{name} already defined" if @factor_symbol[name]
      @factor_symbol[sym] = name
    end
    @factor_symbol[name.to_s] = @factor_value[value] = name
  end

  (data['units'] || {}).each do |name, unit|
    name = name.to_sym
    symbols = [unit['sym'] || []].flatten
    $stderr.puts "Unit #{name} already defined" if @unit[name]
    @unit[name] = { :symbol => symbols.first, :def => parse_unit(unit['def'])  }
    symbols.each do |sym|
      $stderr.puts "Unit symbol #{sym} for #{name} already defined" if @unit_symbol[name]
      @unit_symbol[sym] = name
    end
    @unit_symbol[name.to_s] = name
  end

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

  true
end

#parse_unit(expr) ⇒ Object 



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# File 'lib/unit/system.rb', line 81

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

#validate_unit(units) ⇒ Object 



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# File 'lib/unit/system.rb', line 71

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