Class: Boolean::Expression

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

Defined Under Namespace

Classes: Group, Logic, Name

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(base = Group.new) ⇒ Expression

Returns a new instance of Expression.



83
84
85
 
# File 'lib/boolean/expression.rb', line 83

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

Instance Attribute Details

#base ⇒ Object (readonly)

Returns the value of attribute base.



81
82
83
 
# File 'lib/boolean/expression.rb', line 81

def base
  @base
end

Class Method Details

.[](*args) ⇒ Object 



77
78
79
 
# File 'lib/boolean/expression.rb', line 77

def self.[] (*args)
	parse(*args)
end

.parse(text) ⇒ Object

Raises:

  • (SyntaxError) 


25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
 
# File 'lib/boolean/expression.rb', line 25

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

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

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

			if name || logic
				name  << char if name
				logic << char if logic
			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
		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)

	new(base)
end

Instance Method Details

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



87
88
89
90
91
 
# File 'lib/boolean/expression.rb', line 87

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

#to_s ⇒ Object 



95
96
97
 
# File 'lib/boolean/expression.rb', line 95

def to_s
	@base.inspect
end