# class Set

This library provides the `Set` class, which implements a collection of unordered values with no duplicates. It is a hybrid of Array’s intuitive inter-operation facilities and Hash’s fast lookup.

The method `to_set` is added to `Enumerable` for convenience.

`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.

`Set` uses `Hash` as storage, so you must note the following points:

- Equality of elements is determined according to `Object#eql?` and `Object#hash`. Use `Set#compare_by_identity` to make a set compare its elements by their identity.

- `Set` assumes that the identity of each element does not change while it is stored. Modifying an element of a set will render the set to an unreliable state.

- When a string is to be stored, a frozen copy of the string is stored instead unless the original string is already frozen.

## Comparison¶ ↑

The comparison operators `<`, `>`, `<=`, and `>=` are implemented as shorthand for the {proper_,}{subset?,superset?} methods. The `<=>` operator reflects this order, or return `nil` for sets that both have distinct elements (`{x, y}` vs. `{x, z}` for example).

## Example¶ ↑

    require 'set'
    s1 = Set[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: {1, 2, "foo", 6}>
    s1.subset?(s2)                        #=> false
    s2.subset?(s1)                        #=> true

## Contact¶ ↑

- Akinori MUSHA <knu@iDaemons.org> (current maintainer)

## What’s Here¶ ↑

First, what’s elsewhere. Class Set:

- Inherits from class Object.

- Includes module Enumerable, which provides dozens of additional methods.

In particular, class Set does not have many methods of its own for fetching or for iterating. Instead, it relies on those in Enumerable.

Here, class Set provides methods that are useful for:

- Creating a Set

- Set Operations

- Comparing

- Querying

- Assigning

- Deleting

- Converting

- Iterating

- And more.…

### Methods for Creating a Set¶ ↑

- `::[]`: Returns a new set containing the given objects.

- `::new`: Returns a new set containing either the given objects (if no block given) or the return values from the called block (if a block given).

### Methods for Set Operations¶ ↑

- | (aliased as `union` and `+`): Returns a new set containing all elements from `self` and all elements from a given enumerable (no duplicates).

- & (aliased as `intersection`): Returns a new set containing all elements common to `self` and a given enumerable.

- - (aliased as `difference`): Returns a copy of `self` with all elements in a given enumerable removed.

- ^: Returns a new set containing all elements from `self` and a given enumerable except those common to both.

### Methods for Comparing¶ ↑

- <=>: Returns -1, 0, or 1 as `self` is less than, equal to, or greater than a given object.

- ==: Returns whether `self` and a given enumerable are equal, as determined by `Object#eql?`.

- `compare_by_identity?`: Returns whether the set considers only identity when comparing elements.

### Methods for Querying¶ ↑

- `length` (aliased as `size`): Returns the count of elements.

- `empty?`: Returns whether the set has no elements.

- `include?` (aliased as `member?` and `===`): Returns whether a given object is an element in the set.

- `subset?` (aliased as <=): Returns whether a given object is a subset of the set.

- `proper_subset?` (aliased as <): Returns whether a given enumerable is a proper subset of the set.

- `superset?` (aliased as >=]): Returns whether a given enumerable is a superset of the set.

- `proper_superset?` (aliased as >): Returns whether a given enumerable is a proper superset of the set.

- `disjoint?`: Returns `true` if the set and a given enumerable have no common elements, `false` otherwise.

- `intersect?`: Returns `true` if the set and a given enumerable: have any common elements, `false` otherwise.

- `compare_by_identity?`: Returns whether the set considers only identity when comparing elements.

### Methods for Assigning¶ ↑

- `add` (aliased as `<<`): Adds a given object to the set; returns `self`.

- `add?`: If the given object is not an element in the set, adds it and returns `self`; otherwise, returns `nil`.

- `merge`: Merges the elements of each given enumerable object to the set; returns `self`.

- `replace`: Replaces the contents of the set with the contents of a given enumerable.

### Methods for Deleting¶ ↑

- `clear`: Removes all elements in the set; returns `self`.

- `delete`: Removes a given object from the set; returns `self`.

- `delete?`: If the given object is an element in the set, removes it and returns `self`; otherwise, returns `nil`.

- `subtract`: Removes each given object from the set; returns `self`.

- `delete_if` - Removes elements specified by a given block.

- `select!` (aliased as `filter!`): Removes elements not specified by a given block.

- `keep_if`: Removes elements not specified by a given block.

- `reject!` Removes elements specified by a given block.

### Methods for Converting¶ ↑

- `classify`: Returns a hash that classifies the elements, as determined by the given block.

- `collect!` (aliased as `map!`): Replaces each element with a block return-value.

- `divide`: Returns a hash that classifies the elements, as determined by the given block; differs from `classify` in that the block may accept either one or two arguments.

- `flatten`: Returns a new set that is a recursive flattening of `self`. `flatten!`: Replaces each nested set in `self` with the elements from that set.

- `inspect` (aliased as `to_s`): Returns a string displaying the elements.

- `join`: Returns a string containing all elements, converted to strings as needed, and joined by the given record separator.

- `to_a`: Returns an array containing all set elements.

- `to_set`: Returns `self` if given no arguments and no block; with a block given, returns a new set consisting of block return values.

### Methods for Iterating¶ ↑

- `each`: Calls the block with each successive element; returns `self`.

### Other Methods¶ ↑

- `reset`: Resets the internal state; useful if an object has been modified while an element in the set.

### Constants

VERSION

### Public Class Methods

[](*ary) click to toggle source

Creates a new set containing the given objects.

    Set[1, 2]                   # => #<Set: {1, 2}>
    Set[1, 2, 1]                # => #<Set: {1, 2}>
    Set[1, 'c', :s]             # => #<Set: {1, "c", :s}>

    # File lib/set.rb, line 228
    def self.[](*ary)
      new(ary)
    end

json_create(object) click to toggle source

See `as_json`.

    # File ext/json/lib/json/add/set.rb, line 9
    def self.json_create(object)
      new object['a']
    end

new(enum = nil) { |o| ... } click to toggle source

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.

    Set.new([1, 2])                       #=> #<Set: {1, 2}>
    Set.new([1, 2, 1])                    #=> #<Set: {1, 2}>
    Set.new([1, 'c', :s])                 #=> #<Set: {1, "c", :s}>
    Set.new(1..5)                         #=> #<Set: {1, 2, 3, 4, 5}>
    Set.new([1, 2, 3]) { |x| x * x }      #=> #<Set: {1, 4, 9}>

    # File lib/set.rb, line 243
    def initialize(enum = nil, &block) # :yields: o
      @hash ||= Hash.new(false)

      enum.nil? and return

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

### Public Instance Methods

&(enum) click to toggle source

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

    Set[1, 3, 5] & Set[3, 2, 1]             #=> #<Set: {3, 1}>
    Set['a', 'b', 'z'] & ['a', 'b', 'c']    #=> #<Set: {"a", "b"}>

    # File lib/set.rb, line 640
    def &(enum)
      n = self.class.new
      if enum.is_a?(Set)
        if enum.size > size
          each { |o| n.add(o) if enum.include?(o) }
        else
          enum.each { |o| n.add(o) if include?(o) }
        end
      else
        do_with_enum(enum) { |o| n.add(o) if include?(o) }
      end
      n
    end

Also aliased as: intersection
+(enum)
Alias for: |
-(enum) click to toggle source

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

    Set[1, 3, 5] - Set[1, 5]                #=> #<Set: {3}>
    Set['a', 'b', 'z'] - ['a', 'c']         #=> #<Set: {"b", "z"}>

    # File lib/set.rb, line 630
    def -(enum)
      dup.subtract(enum)
    end

Also aliased as: difference
<(set)
Alias for: proper_subset?
<<(o)
Alias for: add
<=(set)
Alias for: subset?
<=>(set) click to toggle source

Returns 0 if the set are equal, -1 / +1 if the set is a proper subset / superset of the given set, or nil if they both have unique elements.

    # File lib/set.rb, line 453
    def <=>(set)
      return unless set.is_a?(Set)

      case size <=> set.size
      when -1 then -1 if proper_subset?(set)
      when +1 then +1 if proper_superset?(set)
      else 0 if self.==(set)
      end
    end

==(other) click to toggle source

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

    Set[1, 2] == Set[2, 1]                       #=> true
    Set[1, 3, 5] == Set[1, 5]                    #=> false
    Set['a', 'b', 'c'] == Set['a', 'c', 'b']     #=> true
    Set['a', 'b', 'c'] == ['a', 'c', 'b']        #=> false

    # File lib/set.rb, line 674
    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

===(o)

Returns true if the given object is a member of the set, and false otherwise.

Used in case statements:

    require 'set'

    case :apple
    when Set[:potato, :carrot]
      "vegetable"
    when Set[:apple, :banana]
      "fruit"
    end
    # => "fruit"

Or by itself:

    Set[1, 2, 3] === 2   #=> true
    Set[1, 2, 3] === 4   #=> false

Alias for: include?
>(set)
Alias for: proper_superset?
>=(set)
Alias for: superset?
^(enum) click to toggle source

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

    Set[1, 2] ^ Set[2, 3]                   #=> #<Set: {3, 1}>
    Set[1, 'b', 'c'] ^ ['b', 'd']           #=> #<Set: {"d", 1, "c"}>

    # File lib/set.rb, line 661
    def ^(enum)
      n = Set.new(enum)
      each { |o| n.add(o) unless n.delete?(o) }
      n
    end

add(o) click to toggle source

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

    Set[1, 2].add(3)                    #=> #<Set: {1, 2, 3}>
    Set[1, 2].add([3, 4])               #=> #<Set: {1, 2, [3, 4]}>
    Set[1, 2].add(2)                    #=> #<Set: {1, 2}>

    # File lib/set.rb, line 511
    def add(o)
      @hash[o] = true
      self
    end

Also aliased as: <<
add?(o) click to toggle source

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

    Set[1, 2].add?(3)                    #=> #<Set: {1, 2, 3}>
    Set[1, 2].add?([3, 4])               #=> #<Set: {1, 2, [3, 4]}>
    Set[1, 2].add?(2)                    #=> nil

    # File lib/set.rb, line 523
    def add?(o)
      add(o) unless include?(o)
    end

as_json(*) click to toggle source

Methods `Set#as_json` and `Set.json_create` may be used to serialize and deserialize a Set object; see `Marshal`.

Method `Set#as_json` serializes `self`, returning a 2-element hash representing `self`:

    require 'json/add/set'
    x = Set.new(%w/foo bar baz/).as_json
    # => {"json_class"=>"Set", "a"=>["foo", "bar", "baz"]}

Method `JSON.create` deserializes such a hash, returning a Set object:

    Set.json_create(x) # => #<Set: {"foo", "bar", "baz"}>

    # File ext/json/lib/json/add/set.rb, line 28
    def as_json(*)
      {
        JSON.create_id => self.class.name,
        'a'            => to_a,
      }
    end

classify() { |o| ... } click to toggle source

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

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

Returns an enumerator if no block is given.

    # File lib/set.rb, line 743
    def classify # :yields: o
      block_given? or return enum_for(__method__) { size }

      h = {}

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

      h
    end

clear() click to toggle source

Removes all elements and returns self.

    set = Set[1, 'c', :s]             #=> #<Set: {1, "c", :s}>
    set.clear                         #=> #<Set: {}>
    set                               #=> #<Set: {}>

    # File lib/set.rb, line 316
    def clear
      @hash.clear
      self
    end

collect!() { |o| ... } click to toggle source

Replaces the elements with ones returned by `collect()`. Returns an enumerator if no block is given.

    # File lib/set.rb, line 564
    def collect!
      block_given? or return enum_for(__method__) { size }
      set = self.class.new
      each { |o| set << yield(o) }
      replace(set)
    end

Also aliased as: map!
compare_by_identity() click to toggle source

Makes the set compare its elements by their identity and returns self. This method may not be supported by all subclasses of `Set`.

    # File lib/set.rb, line 257
    def compare_by_identity
      if @hash.respond_to?(:compare_by_identity)
        @hash.compare_by_identity
        self
      else
        raise NotImplementedError, "#{self.class.name}\##{__method__} is not implemented"
      end
    end

compare_by_identity?() click to toggle source

Returns true if the set will compare its elements by their identity. Also see `Set#compare_by_identity`.

    # File lib/set.rb, line 268
    def compare_by_identity?
      @hash.respond_to?(:compare_by_identity?) && @hash.compare_by_identity?
    end

delete(o) click to toggle source

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

    # File lib/set.rb, line 529
    def delete(o)
      @hash.delete(o)
      self
    end

delete?(o) click to toggle source

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

    # File lib/set.rb, line 536
    def delete?(o)
      delete(o) if include?(o)
    end

delete_if() { |o| ... } click to toggle source

Deletes every element of the set for which block evaluates to true, and returns self. Returns an enumerator if no block is given.

    # File lib/set.rb, line 543
    def delete_if
      block_given? or return enum_for(__method__) { size }
      # @hash.delete_if should be faster, but using it breaks the order
      # of enumeration in subclasses.
      select { |o| yield o }.each { |o| @hash.delete(o) }
      self
    end

difference(enum)
Alias for: -
disjoint?(set) click to toggle source

Returns true if the set and the given enumerable have no element in common. This method is the opposite of `intersect?`.

    Set[1, 2, 3].disjoint? Set[3, 4]   #=> false
    Set[1, 2, 3].disjoint? Set[4, 5]   #=> true
    Set[1, 2, 3].disjoint? [3, 4]      #=> false
    Set[1, 2, 3].disjoint? 4..5        #=> true

    # File lib/set.rb, line 492
    def disjoint?(set)
      !intersect?(set)
    end

divide(&func) click to toggle source

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).

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

Returns an enumerator if no block is given.

    # File lib/set.rb, line 771
    def divide(&func)
      func or return enum_for(__method__) { size }

      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) click to toggle source

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

    # File lib/set.rb, line 499
    def each(&block)
      block_given? or return enum_for(__method__) { size }
      @hash.each_key(&block)
      self
    end

empty?() click to toggle source

Returns true if the set contains no elements.

    # File lib/set.rb, line 307
    def empty?
      @hash.empty?
    end

filter!(&block)

Equivalent to `Set#select!`

Alias for: select!
flatten() click to toggle source

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

    # File lib/set.rb, line 377
    def flatten
      self.class.new.flatten_merge(self)
    end

flatten!() click to toggle source

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

    # File lib/set.rb, line 383
    def flatten!
      replace(flatten()) if any?(Set)
    end

include?(o) click to toggle source

Returns true if the set contains the given object.

Note that `include?` and `member?` do not test member equality using `==` as do other Enumerables.

See also `Enumerable#include?`

    # File lib/set.rb, line 393
    def include?(o)
      @hash[o]
    end

Also aliased as: member?, ===
initialize_clone(orig, **options) click to toggle source

Clone internal hash.

Calls superclass method

    # File lib/set.rb, line 290
    def initialize_clone(orig, **options)
      super
      @hash = orig.instance_variable_get(:@hash).clone(**options)
    end

initialize_dup(orig) click to toggle source

Dup internal hash.

Calls superclass method

    # File lib/set.rb, line 284
    def initialize_dup(orig)
      super
      @hash = orig.instance_variable_get(:@hash).dup
    end

inspect() click to toggle source

Returns a string containing a human-readable representation of the set (“#<Set: {element1, element2, …}>”).

    # File lib/set.rb, line 811
    def inspect
      ids = (Thread.current[InspectKey] ||= [])

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

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

Also aliased as: to_s
intersect?(set) click to toggle source

Returns true if the set and the given enumerable have at least one element in common.

    Set[1, 2, 3].intersect? Set[4, 5]   #=> false
    Set[1, 2, 3].intersect? Set[3, 4]   #=> true
    Set[1, 2, 3].intersect? 4..5        #=> false
    Set[1, 2, 3].intersect? [3, 4]      #=> true

    # File lib/set.rb, line 470
    def intersect?(set)
      case set
      when Set
        if size < set.size
          any?(set)
        else
          set.any?(self)
        end
      when Enumerable
        set.any?(self)
      else
        raise ArgumentError, "value must be enumerable"
      end
    end

intersection(enum)
Alias for: &
join(separator=nil) click to toggle source

Returns a string created by converting each element of the set to a string See also: `Array#join`

    # File lib/set.rb, line 803
    def join(separator=nil)
      to_a.join(separator)
    end

keep_if() { |o| ... } click to toggle source

Deletes every element of the set for which block evaluates to false, and returns self. Returns an enumerator if no block is given.

    # File lib/set.rb, line 554
    def keep_if
      block_given? or return enum_for(__method__) { size }
      # @hash.keep_if should be faster, but using it breaks the order of
      # enumeration in subclasses.
      reject { |o| yield o }.each { |o| @hash.delete(o) }
      self
    end

length()
Alias for: size
map!()
Alias for: collect!
member?(o)
Alias for: include?
merge(*enums, **nil) click to toggle source

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

    # File lib/set.rb, line 595
    def merge(*enums, **nil)
      enums.each do |enum|
        if enum.instance_of?(self.class)
          @hash.update(enum.instance_variable_get(:@hash))
        else
          do_with_enum(enum) { |o| add(o) }
        end
      end

      self
    end

proper_subset?(set) click to toggle source

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

    # File lib/set.rb, line 438
    def proper_subset?(set)
      case
      when set.instance_of?(self.class) && @hash.respond_to?(:<)
        @hash < set.instance_variable_get(:@hash)
      when set.is_a?(Set)
        size < set.size && all?(set)
      else
        raise ArgumentError, "value must be a set"
      end
    end

Also aliased as: <
proper_superset?(set) click to toggle source

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

    # File lib/set.rb, line 412
    def proper_superset?(set)
      case
      when set.instance_of?(self.class) && @hash.respond_to?(:>)
        @hash > set.instance_variable_get(:@hash)
      when set.is_a?(Set)
        size > set.size && set.all?(self)
      else
        raise ArgumentError, "value must be a set"
      end
    end

Also aliased as: >
reject!(&block) click to toggle source

Equivalent to `Set#delete_if`, but returns nil if no changes were made. Returns an enumerator if no block is given.

    # File lib/set.rb, line 574
    def reject!(&block)
      block_given? or return enum_for(__method__) { size }
      n = size
      delete_if(&block)
      self if size != n
    end

replace(enum) click to toggle source

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

    set = Set[1, 'c', :s]             #=> #<Set: {1, "c", :s}>
    set.replace([1, 2])               #=> #<Set: {1, 2}>
    set                               #=> #<Set: {1, 2}>

    # File lib/set.rb, line 327
    def replace(enum)
      if enum.instance_of?(self.class)
        @hash.replace(enum.instance_variable_get(:@hash))
        self
      else
        do_with_enum(enum)  # make sure enum is enumerable before calling clear
        clear
        merge(enum)
      end
    end

reset() click to toggle source

Resets the internal state after modification to existing elements and returns self.

Elements will be reindexed and deduplicated.

    # File lib/set.rb, line 699
    def reset
      if @hash.respond_to?(:rehash)
        @hash.rehash # This should perform frozenness check.
      else
        raise FrozenError, "can't modify frozen #{self.class.name}" if frozen?
      end
      self
    end

select!(&block) click to toggle source

Equivalent to `Set#keep_if`, but returns nil if no changes were made. Returns an enumerator if no block is given.

    # File lib/set.rb, line 583
    def select!(&block)
      block_given? or return enum_for(__method__) { size }
      n = size
      keep_if(&block)
      self if size != n
    end

Also aliased as: filter!
size() click to toggle source

Returns the number of elements.

    # File lib/set.rb, line 301
    def size
      @hash.size
    end

Also aliased as: length
subset?(set) click to toggle source

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

    # File lib/set.rb, line 425
    def subset?(set)
      case
      when set.instance_of?(self.class) && @hash.respond_to?(:<=)
        @hash <= set.instance_variable_get(:@hash)
      when set.is_a?(Set)
        size <= set.size && all?(set)
      else
        raise ArgumentError, "value must be a set"
      end
    end

Also aliased as: <=
subtract(enum) click to toggle source

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

    # File lib/set.rb, line 609
    def subtract(enum)
      do_with_enum(enum) { |o| delete(o) }
      self
    end

superset?(set) click to toggle source

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

    # File lib/set.rb, line 399
    def superset?(set)
      case
      when set.instance_of?(self.class) && @hash.respond_to?(:>=)
        @hash >= set.instance_variable_get(:@hash)
      when set.is_a?(Set)
        size >= set.size && set.all?(self)
      else
        raise ArgumentError, "value must be a set"
      end
    end

Also aliased as: >=
to_a() click to toggle source

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

    Set[1, 2].to_a                    #=> [1, 2]
    Set[1, 'c', :s].to_a              #=> [1, "c", :s]

    # File lib/set.rb, line 342
    def to_a
      @hash.keys
    end

to_json(*args) click to toggle source

Returns a `JSON` string representing `self`:

    require 'json/add/set'
    puts Set.new(%w/foo bar baz/).to_json

Output:

    {"json_class":"Set","a":["foo","bar","baz"]}

    # File ext/json/lib/json/add/set.rb, line 44
    def to_json(*args)
      as_json.to_json(*args)
    end

to_s()
Alias for: inspect
to_set(klass = Set, *args, &block) click to toggle source

Returns self if no arguments are given. Otherwise, converts the set to another with `klass.new(self, *args, &block)`.

In subclasses, returns `klass.new(self, *args, &block)` unless overridden.

    # File lib/set.rb, line 351
    def to_set(klass = Set, *args, &block)
      return self if instance_of?(Set) && klass == Set && block.nil? && args.empty?
      klass.new(self, *args, &block)
    end

union(enum)
Alias for: |
|(enum) click to toggle source

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

    Set[1, 2, 3] | Set[2, 4, 5]         #=> #<Set: {1, 2, 3, 4, 5}>
    Set[1, 5, 'z'] | (1..6)             #=> #<Set: {1, 5, "z", 2, 3, 4, 6}>

    # File lib/set.rb, line 619
    def |(enum)
      dup.merge(enum)
    end

Also aliased as: +, union