Module: Enumerable

Included in:
Xqsr3::Containers::FrequencyMap, Xqsr3::Containers::MultiMap
Defined in:
lib/xqsr3/extensions/enumerable/unique.rb,
lib/xqsr3/extensions/enumerable/detect_map.rb,
lib/xqsr3/extensions/enumerable/collect_with_index.rb

Instance Method Summary collapse

Instance Method Details

#collect_with_index(base = 0) ⇒ Object

Two-parameter #collect, where the second parameter is a #base-based index, which increments by 1 for each enumerated element.



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# File 'lib/xqsr3/extensions/enumerable/collect_with_index.rb', line 57

def collect_with_index(base = 0)

	a = []

	self.each_with_index do |element, index|

		a.push yield(element, base + index)
	end

	a
end

#detect_map(&block) ⇒ Object

Note:

The block is required (for technical reasons), and must have

The Enumerable#detect method provides a way to detect the presence of a particular value in a collection. The only constraint is that you get back the object unchanged.

The Enumerable#map method provides a way to transform the contents of a collection. The only constraint is that you get back another collection.

This extension method, Enumerable#detect_map combines the features of both, in that it detects the presence of a particular value in a collection and transform the detected value.

[ 1, 2, 3 ].detect_map { |v| -2 * v if v > 2 } # => -6

{ :ab => 'cd', :ef => 'gh' }.detect_map { |k, v| v.upcase if k == :ef } # => 'GH'

arity 1 for sequences or 2 for associations



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# File 'lib/xqsr3/extensions/enumerable/detect_map.rb', line 70

def detect_map &block

	case block.arity
	when 1

		self.each do |v|

			r = yield(v) and return r
		end
	when 2

		self.each do |k, v|

			r = yield(k, v) and return r
		end
	else

		raise ArgumentError, "detect_map requires block with arity of 1 (for sequences) or 2 (for associations); block with arity #{block.arity} given to instance of #{self.class}"
	end

	nil
end

#unique(&block) ⇒ Object

Removes all duplicate elements in a sequence subject to an optional two-parameter block in order to return an array containing unique elements



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# File 'lib/xqsr3/extensions/enumerable/unique.rb', line 58

def unique(&block)

	if not block

		return unique { |a, b| a == b }
	else

		if block.arity != 2

			raise ArgumentError, "block requires two parameters"
		end

		ar	=	self.to_a

		return ar if ar.length < 2

		ar	=	ar.clone

		i	=	0

		while i < ar.length do

			j = i + 1

			while j < ar.length do

				if yield ar[i], ar[j]

					ar.delete_at(j)
				else

					j = j + 1
				end
			end

			i = i + 1
		end

		return ar
	end
end