Class: CommerceUnits::UnitLexer

Inherits:
Object
  • Object
show all
Defined in:
lib/commerce_units/unit_lexer.rb

Defined Under Namespace

Classes: UnexpectedCharacter

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ UnitLexer

Returns a new instance of UnitLexer.



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# File 'lib/commerce_units/unit_lexer.rb', line 22

def initialize
  @tokens = []
  @mode = :new_character
end

Instance Attribute Details

#tokens ⇒ Object

Returns the value of attribute tokens.



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# File 'lib/commerce_units/unit_lexer.rb', line 21

def tokens
  @tokens
end

Class Method Details

.tokenize(string) ⇒ Object 



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# File 'lib/commerce_units/unit_lexer.rb', line 4

def tokenize(string)
  string.split("").inject(new) do |lexer, character|
    case character
    when "*"
      lexer.multiply_token
    when "/"
      lexer.divide_token
    when " "
      lexer.white_space
    when /[a-zA-Z0-9]/
      lexer.character character
    else
      raise UnexpectedCharacter, character
    end
  end.tokens
end

Instance Method Details

#character(character) ⇒ Object 



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# File 'lib/commerce_units/unit_lexer.rb', line 39

def character(character)
  case @mode
  when :new_character
    @tokens << character
    @mode = :character
  when :character, :space
    @tokens[-1] += character
    @mode = :character
  else
    raise UnexpectedCharacter, "character #{character} doesn't belong here"
  end
  self
end

#divide_token ⇒ Object 



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# File 'lib/commerce_units/unit_lexer.rb', line 29

def divide_token
  _operator_token "/"
end

#multiply_token ⇒ Object 



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# File 'lib/commerce_units/unit_lexer.rb', line 26

def multiply_token
  _operator_token "*"
end

#white_space ⇒ Object 



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# File 'lib/commerce_units/unit_lexer.rb', line 32

def white_space
  if :character == @mode
    @tokens[-1] += " "
    @mode = :space
  end
  self
end