Class: Set

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/set.rb

Overview

Set implements a collection of unordered values with no duplicates. This is a hybrid of Array’s intuitive inter-operation facilities and Hash’s fast lookup.

The equality of each couple of elements is determined according to Object#eql? and Object#hash, since Set uses Hash as storage.

Set is easy to use with Enumerable objects (implementing each). Most of the initializer methods and binary operators accept generic Enumerable objects besides sets and arrays. An Enumerable object can be converted to Set using the to_set method.

Comparison

The comparison operators <, >, <= and >= are implemented as shorthand for the proper_,subset?,superset? methods. However, the <=> operator is intentionally left out because not every pair of sets is comparable. (x,y vs. x,z for example)

Example

require 'set'
s1 = Set.new [1, 2]                   # -> #<Set: {1, 2}>
s2 = [1, 2].to_set                    # -> #<Set: {1, 2}>
s1 == s2                              # -> true
s1.add("foo")                         # -> #<Set: {1, 2, "foo"}>
s1.merge([2, 6])                      # -> #<Set: {6, 1, 2, "foo"}>
s1.subset? s2                         # -> false
s2.subset? s1                         # -> true

Contact

- Akinori MUSHA <[email protected]> (current maintainer)

Direct Known Subclasses

SortedSet

Constant Summary collapse

InspectKey =

:nodoc:

:__inspect_key__

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Enumerable

#to_set

Constructor Details

#initialize(enum = nil, &block) ⇒ Set

Creates a new set containing the elements of the given enumerable object.

If a block is given, the elements of enum are preprocessed by the given block.



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# File 'lib/set.rb', line 73

def initialize(enum = nil, &block) # :yields: o
  @hash ||= Hash.new

  enum.nil? and return

  if block
    do_with_enum(enum) { |o| add(block[o]) }
  else
    merge(enum)
  end
end

Class Method Details

.[](*ary) ⇒ Object

Creates a new set containing the given objects.



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# File 'lib/set.rb', line 64

def self.[](*ary)
  new(ary)
end

Instance Method Details

#&(enum) ⇒ Object Also known as: intersection

Returns a new set containing elements common to the set and the given enumerable object.



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# File 'lib/set.rb', line 350

def &(enum)
  n = self.class.new
  do_with_enum(enum) { |o| n.add(o) if include?(o) }
  n
end

#-(enum) ⇒ Object Also known as: difference

Returns a new set built by duplicating the set, removing every element that appears in the given enumerable object.



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# File 'lib/set.rb', line 343

def -(enum)
  dup.subtract(enum)
end

#==(other) ⇒ Object

Returns true if two sets are equal. The equality of each couple of elements is defined according to Object#eql?.



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# File 'lib/set.rb', line 368

def ==(other)
  if self.equal?(other)
    true
  elsif other.instance_of?(self.class)
    @hash == other.instance_variable_get(:@hash)
  elsif other.is_a?(Set) && self.size == other.size
    other.all? { |o| @hash.include?(o) }
  else
    false
  end
end

#^(enum) ⇒ Object

Returns a new set containing elements exclusive between the set and the given enumerable object. (set ^ enum) is equivalent to ((set | enum) - (set & enum)).



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# File 'lib/set.rb', line 360

def ^(enum)
  n = Set.new(enum)
  each { |o| if n.include?(o) then n.delete(o) else n.add(o) end }
  n
end

#add(o) ⇒ Object Also known as: <<

Adds the given object to the set and returns self. Use merge to add many elements at once.



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# File 'lib/set.rb', line 238

def add(o)
  @hash[o] = true
  self
end

#add?(o) ⇒ Boolean

Adds the given object to the set and returns self. If the object is already in the set, returns nil.

Returns:

  • (Boolean) 


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# File 'lib/set.rb', line 246

def add?(o)
  if include?(o)
    nil
  else
    add(o)
  end
end

#classify ⇒ Object

Classifies the set by the return value of the given block and returns a hash of => set of elements pairs. The block is called once for each element of the set, passing the element as parameter.

e.g.:

require 'set'
files = Set.new(Dir.glob("*.rb"))
hash = files.classify { |f| File.mtime(f).year }
p hash    # => {2000=>#<Set: {"a.rb", "b.rb"}>,
          #     2001=>#<Set: {"c.rb", "d.rb", "e.rb"}>,
          #     2002=>#<Set: {"f.rb"}>}



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# File 'lib/set.rb', line 402

def classify # :yields: o
  block_given? or return enum_for(__method__)

  h = {}

  each { |i|
    x = yield(i)
    (h[x] ||= self.class.new).add(i)
  }

  h
end

#clear ⇒ Object

Removes all elements and returns self.



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# File 'lib/set.rb', line 131

def clear
  @hash.clear
  self
end

#collect! ⇒ Object Also known as: map!

Replaces the elements with ones returned by collect().



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# File 'lib/set.rb', line 288

def collect!
  block_given? or return enum_for(__method__)
  set = self.class.new
  each { |o| set << yield(o) }
  replace(set)
end

#delete(o) ⇒ Object

Deletes the given object from the set and returns self. Use subtract to delete many items at once.



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# File 'lib/set.rb', line 256

def delete(o)
  @hash.delete(o)
  self
end

#delete?(o) ⇒ Boolean

Deletes the given object from the set and returns self. If the object is not in the set, returns nil.

Returns:

  • (Boolean) 


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# File 'lib/set.rb', line 263

def delete?(o)
  if include?(o)
    delete(o)
  else
    nil
  end
end

#delete_if ⇒ Object

Deletes every element of the set for which block evaluates to true, and returns self.



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# File 'lib/set.rb', line 273

def delete_if
  block_given? or return enum_for(__method__)
  to_a.each { |o| @hash.delete(o) if yield(o) }
  self
end

#divide(&func) ⇒ Object

Divides the set into a set of subsets according to the commonality defined by the given block.

If the arity of the block is 2, elements o1 and o2 are in common if block.call(o1, o2) is true. Otherwise, elements o1 and o2 are in common if block.call(o1) == block.call(o2).

e.g.:

require 'set'
numbers = Set[1, 3, 4, 6, 9, 10, 11]
set = numbers.divide { |i,j| (i - j).abs == 1 }
p set     # => #<Set: {#<Set: {1}>,
          #            #<Set: {11, 9, 10}>,
          #            #<Set: {3, 4}>,
          #            #<Set: {6}>}>



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# File 'lib/set.rb', line 431

def divide(&func)
  func or return enum_for(__method__)

  if func.arity == 2
    require 'tsort'

    class << dig = {}         # :nodoc:
      include TSort

      alias tsort_each_node each_key
      def tsort_each_child(node, &block)
        fetch(node).each(&block)
      end
    end

    each { |u|
      dig[u] = a = []
      each{ |v| func.call(u, v) and a << v }
    }

    set = Set.new()
    dig.each_strongly_connected_component { |css|
      set.add(self.class.new(css))
    }
    set
  else
    Set.new(classify(&func).values)
  end
end

#each(&block) ⇒ Object

Calls the given block once for each element in the set, passing the element as parameter. Returns an enumerator if no block is given.



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# File 'lib/set.rb', line 230

def each(&block)
  block or return enum_for(__method__)
  @hash.each_key(&block)
  self
end

#empty? ⇒ Boolean

Returns true if the set contains no elements.

Returns:

  • (Boolean) 


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# File 'lib/set.rb', line 126

def empty?
  @hash.empty?
end

#eql?(o) ⇒ Boolean

:nodoc:

Returns:

  • (Boolean) 


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# File 'lib/set.rb', line 384

def eql?(o)   # :nodoc:
  return false unless o.is_a?(Set)
  @hash.eql?(o.instance_variable_get(:@hash))
end

#flatten ⇒ Object

Returns a new set that is a copy of the set, flattening each containing set recursively.



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# File 'lib/set.rb', line 175

def flatten
  self.class.new.flatten_merge(self)
end

#flatten! ⇒ Object

Equivalent to Set#flatten, but replaces the receiver with the result in place. Returns nil if no modifications were made.



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# File 'lib/set.rb', line 181

def flatten!
  if detect { |e| e.is_a?(Set) }
    replace(flatten())
  else
    nil
  end
end

#freeze ⇒ Object

:nodoc:



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# File 'lib/set.rb', line 101

def freeze    # :nodoc:
  super
  @hash.freeze
  self
end

#hash ⇒ Object

:nodoc:



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# File 'lib/set.rb', line 380

def hash      # :nodoc:
  @hash.hash
end

#include?(o) ⇒ Boolean Also known as: member?

Returns true if the set contains the given object.

Returns:

  • (Boolean) 


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# File 'lib/set.rb', line 190

def include?(o)
  @hash.include?(o)
end

#initialize_copy(orig) ⇒ Object

Copy internal hash.



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# File 'lib/set.rb', line 97

def initialize_copy(orig)
  @hash = orig.instance_variable_get(:@hash).dup
end

#inspect ⇒ Object

Returns a string containing a human-readable representation of the set. (“#<Set: element2, …>”)



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# File 'lib/set.rb', line 465

def inspect
  ids = (Thread.current[InspectKey] ||= [])

  if ids.include?(object_id)
    return sprintf('#<%s: {...}>', self.class.name)
  end

  begin
    ids << object_id
    return sprintf('#<%s: {%s}>', self.class, to_a.inspect[1..-2])
  ensure
    ids.pop
  end
end

#keep_if ⇒ Object

Deletes every element of the set for which block evaluates to false, and returns self.



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# File 'lib/set.rb', line 281

def keep_if
  block_given? or return enum_for(__method__)
  to_a.each { |o| @hash.delete(o) unless yield(o) }
  self
end

#merge(enum) ⇒ Object

Merges the elements of the given enumerable object to the set and returns self.



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# File 'lib/set.rb', line 316

def merge(enum)
  if enum.instance_of?(self.class)
    @hash.update(enum.instance_variable_get(:@hash))
  else
    do_with_enum(enum) { |o| add(o) }
  end

  self
end

#pretty_print(pp) ⇒ Object

:nodoc:



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# File 'lib/set.rb', line 480

def pretty_print(pp)  # :nodoc:
  pp.text sprintf('#<%s: {', self.class.name)
  pp.nest(1) {
    pp.seplist(self) { |o|
      pp.pp o
    }
  }
  pp.text "}>"
end

#pretty_print_cycle(pp) ⇒ Object

:nodoc:



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# File 'lib/set.rb', line 490

def pretty_print_cycle(pp)    # :nodoc:
  pp.text sprintf('#<%s: {%s}>', self.class.name, empty? ? '' : '...')
end

#proper_subset?(set) ⇒ Boolean Also known as: <

Returns true if the set is a proper subset of the given set.

Returns:

  • (Boolean) 


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# File 'lib/set.rb', line 220

def proper_subset?(set)
  set.is_a?(Set) or raise ArgumentError, "value must be a set"
  return false if set.size <= size
  all? { |o| set.include?(o) }
end

#proper_superset?(set) ⇒ Boolean Also known as: >

Returns true if the set is a proper superset of the given set.

Returns:

  • (Boolean) 


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# File 'lib/set.rb', line 204

def proper_superset?(set)
  set.is_a?(Set) or raise ArgumentError, "value must be a set"
  return false if size <= set.size
  set.all? { |o| include?(o) }
end

#reject!(&block) ⇒ Object

Equivalent to Set#delete_if, but returns nil if no changes were made.



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# File 'lib/set.rb', line 298

def reject!(&block)
  block or return enum_for(__method__)
  n = size
  delete_if(&block)
  size == n ? nil : self
end

#replace(enum) ⇒ Object

Replaces the contents of the set with the contents of the given enumerable object and returns self.



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# File 'lib/set.rb', line 138

def replace(enum)
  if enum.instance_of?(self.class)
    @hash.replace(enum.instance_variable_get(:@hash))
  else
    clear
    merge(enum)
  end

  self
end

#select!(&block) ⇒ Object

Equivalent to Set#keep_if, but returns nil if no changes were made.



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# File 'lib/set.rb', line 307

def select!(&block)
  block or return enum_for(__method__)
  n = size
  keep_if(&block)
  size == n ? nil : self
end

#size ⇒ Object Also known as: length

Returns the number of elements.



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# File 'lib/set.rb', line 120

def size
  @hash.size
end

#subset?(set) ⇒ Boolean Also known as: <=

Returns true if the set is a subset of the given set.

Returns:

  • (Boolean) 


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# File 'lib/set.rb', line 212

def subset?(set)
  set.is_a?(Set) or raise ArgumentError, "value must be a set"
  return false if set.size < size
  all? { |o| set.include?(o) }
end

#subtract(enum) ⇒ Object

Deletes every element that appears in the given enumerable object and returns self.



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# File 'lib/set.rb', line 328

def subtract(enum)
  do_with_enum(enum) { |o| delete(o) }
  self
end

#superset?(set) ⇒ Boolean Also known as: >=

Returns true if the set is a superset of the given set.

Returns:

  • (Boolean) 


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# File 'lib/set.rb', line 196

def superset?(set)
  set.is_a?(Set) or raise ArgumentError, "value must be a set"
  return false if size < set.size
  set.all? { |o| include?(o) }
end

#taint ⇒ Object

:nodoc:



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# File 'lib/set.rb', line 107

def taint     # :nodoc:
  super
  @hash.taint
  self
end

#to_a ⇒ Object

Converts the set to an array. The order of elements is uncertain.



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# File 'lib/set.rb', line 150

def to_a
  @hash.keys
end

#untaint ⇒ Object

:nodoc:



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# File 'lib/set.rb', line 113

def untaint   # :nodoc:
  super
  @hash.untaint
  self
end

#|(enum) ⇒ Object Also known as: +, union

Returns a new set built by merging the set and the elements of the given enumerable object.



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# File 'lib/set.rb', line 335

def |(enum)
  dup.merge(enum)
end