Class: Boolean::Expression

Inherits:
Object
  • Object
show all
Defined in:
lib/boolean/expression.rb

Defined Under Namespace

Classes: Group, Logic, Name

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(base = Group.new) ⇒ Expression

Returns a new instance of Expression.



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# File 'lib/boolean/expression.rb', line 125

def initialize (base = Group.new)
	@base = base
end

Class Method Details

.parse(text) ⇒ Object Also known as: []

Raises:

  • (SyntaxError) 


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# File 'lib/boolean/expression.rb', line 26

def parse (text)
	base   = Group.new
	name   = nil
	stack  = [base]
	logic  = nil
	string = false
	quoted = false

	text.to_s.chars.each_with_index {|char, index|
		begin
			if !string && char == ')' && stack.length == 1
				raise SyntaxError, 'closing an unopened parenthesis'
			end

			if !string && (char.match(/\s|\(|\)/) || (!logic && ['|', '&', '!'].member?(char)))
				if logic || (name && name.match(/^(and|or|not)$/i) && !quoted)
					stack.last << Logic.new(logic || name)
					logic       = nil
					name        = nil
				elsif name
					stack.last << Name.new(name)
					name        = nil
					quoted      = false
				end
			end

			if name
				if char == '"'
					string = false
				else
					name << char
				end
			elsif logic
				logic << char
			else
				if char == '"'
					string = true
					quoted = true

					next
				end

				if string
					name = char unless name
				else
					case char
						when '(' then stack.push Group.new
						when ')' then stack[-2] << stack.pop
						when '|' then logic = '|'
						when '&' then logic = '&'
						when '!' then stack.last << Logic.new('!')
						else          name = char if !char.match(/\s/)
					end
				end
			end
		rescue SyntaxError => e
			raise "#{e.message} near `#{text[index - 4, 8]}` at character #{index}"
		end
	}

	raise SyntaxError, 'not all parenthesis are closed' if stack.length != 1
	
	raise SyntaxError, 'the expression cannot end with a logic operator' if logic

	base << Name.new(name) if name

	base = base.first if base.length == 1 && base.first.is_a?(Group)

	_check(base)

	new(base)
end

Instance Method Details

#evaluate(*args) ⇒ Object Also known as: [] 



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# File 'lib/boolean/expression.rb', line 129

def evaluate (*args)
	_evaluate(@base, args.flatten.compact.map {|piece|
		piece.to_s
	})
end

#names ⇒ Object 



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# File 'lib/boolean/expression.rb', line 137

def names
	_names(@base).compact.uniq
end

#to_a ⇒ Object 



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# File 'lib/boolean/expression.rb', line 149

def to_a
	@base.to_a
end

#to_group ⇒ Object 



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# File 'lib/boolean/expression.rb', line 145

def to_group
	@base
end

#to_s ⇒ Object 



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# File 'lib/boolean/expression.rb', line 141

def to_s
	@base.inspect
end