Class: Stream::FromArray

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

Overview

A stream implemented based on an Array. This class is immutable and thread-safe.

Author

Mihai Andronache ([email protected])

Since

0.0.1

Instance Method Summary collapse

Constructor Details

#initialize(array) ⇒ FromArray

Returns a new instance of FromArray.



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# File 'lib/fromarray.rb', line 31

def initialize(array)
  @array = array
end

Instance Method Details

#all_match(&test) ⇒ Object

Returns true if all the elements of the Stream are matching the given predicate (a function which performs a test on the value and should return a boolean).

If the stream is empty, the returned value is true and the predicate is not called at all.

This is a terminal operation.

test

A function which should perform some boolean test on the

given value.



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# File 'lib/fromarray.rb', line 110

def all_match(&test)
  @array.each do |val|
    return false unless test.call(val)
  end
  true
end

#any_match(&test) ⇒ Object

Returns true if any of the elements of the Stream are matching the given predicate (a function which performs a test on the value and should return a boolean). Iteration will stop at the first match.

If the stream is empty, the returned value is false and the predicate is not called at all.

This is a terminal operation.

test

A function which should perform some boolean test on the

given value.



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# File 'lib/fromarray.rb', line 128

def any_match(&test)
  @array.each do |val|
    return true if test.call(val)
  end
  false
end

#collect ⇒ Object

Collect the stream’s data into an array and return it. This is a terminal operation.



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# File 'lib/fromarray.rb', line 137

def collect
  @array.dup
end

#count ⇒ Object

Return the number of elements in this stream. This is a terminal operation.



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# File 'lib/fromarray.rb', line 37

def count
  @array.length
end

#distinct ⇒ Object

Remove all the duplicates from the stream. This is an intermediary operation.



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# File 'lib/fromarray.rb', line 79

def distinct
  unique = []
  @array.each do |val|
    unique.push(val) unless unique.include? val
  end
  FromArray.new(unique)
end

#filter(&condition) ⇒ Object

Filter out the elements which are not satisfying the given condition. Example:

stream = Stream::FromArray.new([1, 2, 3, 4, 5]) collected = stream.filter {|num| num % 2 == 0}.collect puts collected # [2, 4]

This is an intermediary operation.

condition

Ruby Block taking one parameter (the stream element) and returning a boolean check on it.



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# File 'lib/fromarray.rb', line 51

def filter(&condition)
  filtered = []
  @array.each do |val|
    filtered.push(val) unless condition.call(val) == false
  end
  FromArray.new(filtered)
end

#map(&function) ⇒ Object

Map the stream’s elements to a given value using a function. Example (map int to string):

stream = Stream::FromArray.new([1, 2, 3]) collected = stream.map {|num| num.to_s}.collect puts collected # [‘1’, ‘2’, ‘3’]

This is an intermediary operation.

function

Ruby Block function taking one parameter (the element in the stream).



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# File 'lib/fromarray.rb', line 69

def map(&function)
  mapped = []
  @array.each do |val|
    mapped.push(function.call(val))
  end
  FromArray.new(mapped)
end

#skip(count) ⇒ Object

Skip the first n elements of the stream. This is an intermediary operation.

count

Number of elements to skip from the beginning of the stream.

Raises:

  • (ArgumentError) 


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# File 'lib/fromarray.rb', line 90

def skip(count)
  raise ArgumentError, 'count has to be positive integer' unless count.positive? and count.is_a? Integer

  skipped = []
  @array.each_with_index do |val, index|
    skipped.push(val) unless index + 1 <= count
  end
  FromArray.new(skipped)
end