Class: Tins::Unit::UnitParser

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

Constant Summary collapse

NUMBER = 
/([+-]?
  (?:0|[1-9]\d*)
  (?:
    \.\d+(?i:e[+-]?\d+) |
    \.\d+ |
    (?i:e[+-]?\d+)
  )?
)/x

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(source, unit, prefixes = nil) ⇒ UnitParser

Returns a new instance of UnitParser.



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# File 'lib/tins/unit.rb', line 62

def initialize(source, unit, prefixes = nil)
  super source
  if prefixes
    @unit_re    = unit_re(Tins::Unit.prefixes(prefixes), unit)
    @unit_lc_re = @unit_uc_re = nil
  else
    @unit_lc_re = unit_re(Tins::Unit.prefixes(:lc), unit)
    @unit_uc_re = unit_re(Tins::Unit.prefixes(:uc), unit)
    @unit_re    = nil
  end
  @number       = 1.0
end

Instance Attribute Details

#number ⇒ Object (readonly)

Returns the value of attribute number.



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# File 'lib/tins/unit.rb', line 87

def number
  @number
end

Instance Method Details

#parse ⇒ Object

Raises:

  • (NotImplementedError) 


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# File 'lib/tins/unit.rb', line 117

def parse
  raise NotImplementedError
end

#scan(re) ⇒ Object 



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# File 'lib/tins/unit.rb', line 89

def scan(re)
  re.nil? and return
  super
end

#scan_char(char) ⇒ Object 



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# File 'lib/tins/unit.rb', line 113

def scan_char(char)
  scan(/#{char}/) or return
end

#scan_number ⇒ Object 



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# File 'lib/tins/unit.rb', line 94

def scan_number
  scan(NUMBER) or return
  @number *= BigDecimal(self[1])
end

#scan_unit ⇒ Object 



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# File 'lib/tins/unit.rb', line 99

def scan_unit
  case
  when scan(@unit_re)
    prefix = @unit_re.prefixes.find { |pre| pre.name == self[1] } or return
    @number *= prefix.multiplier
  when scan(@unit_lc_re)
    prefix = @unit_lc_re.prefixes.find { |pre| pre.name == self[1] } or return
    @number *= prefix.multiplier
  when scan(@unit_uc_re)
    prefix = @unit_uc_re.prefixes.find { |pre| pre.name == self[1] } or return
    @number *= prefix.multiplier
  end
end