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diff --git a/lib/immutable/_core.rb b/lib/immutable/_core.rb new file mode 100644 index 0000000..a7bb58e --- /dev/null +++ b/lib/immutable/_core.rb @@ -0,0 +1,3067 @@ +require 'immutable/undefined' +require 'immutable/enumerable' +require 'immutable/trie' +require 'immutable/sorted_set' +require 'set' + +module Immutable + + # An `Immutable::Hash` maps a set of unique keys to corresponding values, much + # like a dictionary maps from words to definitions. Given a key, it can store + # and retrieve an associated value in constant time. If an existing key is + # stored again, the new value will replace the old. It behaves much like + # Ruby's built-in Hash, which we will call RubyHash for clarity. Like + # RubyHash, two keys that are `#eql?` to each other and have the same + # `#hash` are considered identical in an `Immutable::Hash`. + # + # An `Immutable::Hash` can be created in a couple of ways: + # + # Immutable::Hash.new(font_size: 10, font_family: 'Arial') + # Immutable::Hash[first_name: 'John', last_name: 'Smith'] + # + # Any `Enumerable` object which yields two-element `[key, value]` arrays + # can be used to initialize an `Immutable::Hash`: + # + # Immutable::Hash.new([[:first_name, 'John'], [:last_name, 'Smith']]) + # + # Key/value pairs can be added using {#put}. A new hash is returned and the + # existing one is left unchanged: + # + # hash = Immutable::Hash[a: 100, b: 200] + # hash.put(:c, 500) # => Immutable::Hash[:a => 100, :b => 200, :c => 500] + # hash # => Immutable::Hash[:a => 100, :b => 200] + # + # {#put} can also take a block, which is used to calculate the value to be + # stored. + # + # hash.put(:a) { |current| current + 200 } # => Immutable::Hash[:a => 300, :b => 200] + # + # Since it is immutable, all methods which you might expect to "modify" a + # `Immutable::Hash` actually return a new hash and leave the existing one + # unchanged. This means that the `hash[key] = value` syntax from RubyHash + # *cannot* be used with `Immutable::Hash`. + # + # Nested data structures can easily be updated using {#update_in}: + # + # hash = Immutable::Hash["a" => Immutable::Vector[Immutable::Hash["c" => 42]]] + # hash.update_in("a", 0, "c") { |value| value + 5 } + # # => Immutable::Hash["a" => Immutable::Hash["b" => Immutable::Hash["c" => 47]]] + # + # While an `Immutable::Hash` can iterate over its keys or values, it does not + # guarantee any specific iteration order (unlike RubyHash). Methods like + # {#flatten} do not guarantee the order of returned key/value pairs. + # + # Like RubyHash, an `Immutable::Hash` can have a default block which is used + # when looking up a key that does not exist. Unlike RubyHash, the default + # block will only be passed the missing key, without the hash itself: + # + # hash = Immutable::Hash.new { |missing_key| missing_key * 10 } + # hash[5] # => 50 + class Hash + include Immutable::Enumerable + + class << self + # Create a new `Hash` populated with the given key/value pairs. + # + # @example + # Immutable::Hash["A" => 1, "B" => 2] # => Immutable::Hash["A" => 1, "B" => 2] + # Immutable::Hash[["A", 1], ["B", 2]] # => Immutable::Hash["A" => 1, "B" => 2] + # + # @param pairs [::Enumerable] initial content of hash. An empty hash is returned if not provided. + # @return [Hash] + def [](pairs = nil) + (pairs.nil? || pairs.empty?) ? empty : new(pairs) + end + + # Return an empty `Hash`. If used on a subclass, returns an empty instance + # of that class. + # + # @return [Hash] + def empty + @empty ||= new + end + + # "Raw" allocation of a new `Hash`. Used internally to create a new + # instance quickly after obtaining a modified {Trie}. + # + # @return [Hash] + # @private + def alloc(trie = EmptyTrie, block = nil) + obj = allocate + obj.instance_variable_set(:@trie, trie) + obj.instance_variable_set(:@default, block) + obj.freeze + end + end + + # @param pairs [::Enumerable] initial content of hash. An empty hash is returned if not provided. + # @yield [key] Optional _default block_ to be stored and used to calculate the default value of a missing key. It will not be yielded during this method. It will not be preserved when marshalling. + # @yieldparam key Key that was not present in the hash. + def initialize(pairs = nil, &block) + @trie = pairs ? Trie[pairs] : EmptyTrie + @default = block + freeze + end + + # Return the default block if there is one. Otherwise, return `nil`. + # + # @return [Proc] + def default_proc + @default + end + + # Return the number of key/value pairs in this `Hash`. + # + # @example + # Immutable::Hash["A" => 1, "B" => 2, "C" => 3].size # => 3 + # + # @return [Integer] + def size + @trie.size + end + alias length size + + # Return `true` if this `Hash` contains no key/value pairs. + # + # @return [Boolean] + def empty? + @trie.empty? + end + + # Return `true` if the given key object is present in this `Hash`. More precisely, + # return `true` if a key with the same `#hash` code, and which is also `#eql?` + # to the given key object is present. + # + # @example + # Immutable::Hash["A" => 1, "B" => 2, "C" => 3].key?("B") # => true + # + # @param key [Object] The key to check for + # @return [Boolean] + def key?(key) + @trie.key?(key) + end + alias has_key? key? + alias include? key? + alias member? key? + + # Return `true` if this `Hash` has one or more keys which map to the provided value. + # + # @example + # Immutable::Hash["A" => 1, "B" => 2, "C" => 3].value?(2) # => true + # + # @param value [Object] The value to check for + # @return [Boolean] + def value?(value) + each { |k,v| return true if value == v } + false + end + alias has_value? value? + + # Retrieve the value corresponding to the provided key object. If not found, and + # this `Hash` has a default block, the default block is called to provide the + # value. Otherwise, return `nil`. + # + # @example + # h = Immutable::Hash["A" => 1, "B" => 2, "C" => 3] + # h["B"] # => 2 + # h.get("B") # => 2 + # h.get("Elephant") # => nil + # + # # Immutable Hash with a default proc: + # h = Immutable::Hash.new("A" => 1, "B" => 2, "C" => 3) { |key| key.size } + # h.get("B") # => 2 + # h.get("Elephant") # => 8 + # + # @param key [Object] The key to look up + # @return [Object] + def get(key) + entry = @trie.get(key) + if entry + entry[1] + elsif @default + @default.call(key) + end + end + alias [] get + + # Retrieve the value corresponding to the given key object, or use the provided + # default value or block, or otherwise raise a `KeyError`. + # + # @overload fetch(key) + # Retrieve the value corresponding to the given key, or raise a `KeyError` + # if it is not found. + # @param key [Object] The key to look up + # @overload fetch(key) { |key| ... } + # Retrieve the value corresponding to the given key, or call the optional + # code block (with the missing key) and get its return value. + # @yield [key] The key which was not found + # @yieldreturn [Object] Object to return since the key was not found + # @param key [Object] The key to look up + # @overload fetch(key, default) + # Retrieve the value corresponding to the given key, or else return + # the provided `default` value. + # @param key [Object] The key to look up + # @param default [Object] Object to return if the key is not found + # + # @example + # h = Immutable::Hash["A" => 1, "B" => 2, "C" => 3] + # h.fetch("B") # => 2 + # h.fetch("Elephant") # => KeyError: key not found: "Elephant" + # + # # with a default value: + # h.fetch("B", 99) # => 2 + # h.fetch("Elephant", 99) # => 99 + # + # # with a block: + # h.fetch("B") { |key| key.size } # => 2 + # h.fetch("Elephant") { |key| key.size } # => 8 + # + # @return [Object] + def fetch(key, default = Undefined) + entry = @trie.get(key) + if entry + entry[1] + elsif block_given? + yield(key) + elsif default != Undefined + default + else + raise KeyError, "key not found: #{key.inspect}" + end + end + + # Return a new `Hash` with the existing key/value associations, plus an association + # between the provided key and value. If an equivalent key is already present, its + # associated value will be replaced with the provided one. + # + # If the `value` argument is missing, but an optional code block is provided, + # it will be passed the existing value (or `nil` if there is none) and what it + # returns will replace the existing value. This is useful for "transforming" + # the value associated with a certain key. + # + # Avoid mutating objects which are used as keys. `String`s are an exception: + # unfrozen `String`s which are used as keys are internally duplicated and + # frozen. This matches RubyHash's behaviour. + # + # @example + # h = Immutable::Hash["A" => 1, "B" => 2] + # h.put("C", 3) + # # => Immutable::Hash["A" => 1, "B" => 2, "C" => 3] + # h.put("B") { |value| value * 10 } + # # => Immutable::Hash["A" => 1, "B" => 20] + # + # @param key [Object] The key to store + # @param value [Object] The value to associate it with + # @yield [value] The previously stored value, or `nil` if none. + # @yieldreturn [Object] The new value to store + # @return [Hash] + def put(key, value = yield(get(key))) + new_trie = @trie.put(key, value) + if new_trie.equal?(@trie) + self + else + self.class.alloc(new_trie, @default) + end + end + + # @private + # @raise NoMethodError + def []=(*) + raise NoMethodError, "Immutable::Hash doesn't support `[]='; use `put' instead" + end + + # Return a new `Hash` with a deeply nested value modified to the result of + # the given code block. When traversing the nested `Hash`es and `Vector`s, + # non-existing keys are created with empty `Hash` values. + # + # The code block receives the existing value of the deeply nested key (or + # `nil` if it doesn't exist). This is useful for "transforming" the value + # associated with a certain key. + # + # Note that the original `Hash` and sub-`Hash`es and sub-`Vector`s are left + # unmodified; new data structure copies are created along the path wherever + # needed. + # + # @example + # hash = Immutable::Hash["a" => Immutable::Hash["b" => Immutable::Hash["c" => 42]]] + # hash.update_in("a", "b", "c") { |value| value + 5 } + # # => Immutable::Hash["a" => Immutable::Hash["b" => Immutable::Hash["c" => 47]]] + # + # @param key_path [::Array<Object>] List of keys which form the path to the key to be modified + # @yield [value] The previously stored value + # @yieldreturn [Object] The new value to store + # @return [Hash] + def update_in(*key_path, &block) + if key_path.empty? + raise ArgumentError, 'must have at least one key in path' + end + key = key_path[0] + if key_path.size == 1 + new_value = block.call(get(key)) + else + value = fetch(key, EmptyHash) + new_value = value.update_in(*key_path[1..-1], &block) + end + put(key, new_value) + end + + # An alias for {#put} to match RubyHash's API. Does not support {#put}'s + # block form. + # + # @see #put + # @param key [Object] The key to store + # @param value [Object] The value to associate it with + # @return [Hash] + def store(key, value) + put(key, value) + end + + # Return a new `Hash` with `key` removed. If `key` is not present, return + # `self`. + # + # @example + # Immutable::Hash["A" => 1, "B" => 2, "C" => 3].delete("B") + # # => Immutable::Hash["A" => 1, "C" => 3] + # + # @param key [Object] The key to remove + # @return [Hash] + def delete(key) + derive_new_hash(@trie.delete(key)) + end + + # Call the block once for each key/value pair in this `Hash`, passing the key/value + # pair as parameters. No specific iteration order is guaranteed, though the order will + # be stable for any particular `Hash`. + # + # @example + # Immutable::Hash["A" => 1, "B" => 2, "C" => 3].each { |k, v| puts "k=#{k} v=#{v}" } + # + # k=A v=1 + # k=C v=3 + # k=B v=2 + # # => Immutable::Hash["A" => 1, "B" => 2, "C" => 3] + # + # @yield [key, value] Once for each key/value pair. + # @return [self] + def each(&block) + return to_enum if not block_given? + @trie.each(&block) + self + end + alias each_pair each + + # Call the block once for each key/value pair in this `Hash`, passing the key/value + # pair as parameters. Iteration order will be the opposite of {#each}. + # + # @example + # Immutable::Hash["A" => 1, "B" => 2, "C" => 3].reverse_each { |k, v| puts "k=#{k} v=#{v}" } + # + # k=B v=2 + # k=C v=3 + # k=A v=1 + # # => Immutable::Hash["A" => 1, "B" => 2, "C" => 3] + # + # @yield [key, value] Once for each key/value pair. + # @return [self] + def reverse_each(&block) + return enum_for(:reverse_each) if not block_given? + @trie.reverse_each(&block) + self + end + + # Call the block once for each key/value pair in this `Hash`, passing the key as a + # parameter. Ordering guarantees are the same as {#each}. + # + # @example + # Immutable::Hash["A" => 1, "B" => 2, "C" => 3].each_key { |k| puts "k=#{k}" } + # + # k=A + # k=C + # k=B + # # => Immutable::Hash["A" => 1, "B" => 2, "C" => 3] + # + # @yield [key] Once for each key/value pair. + # @return [self] + def each_key + return enum_for(:each_key) if not block_given? + @trie.each { |k,v| yield k } + self + end + + # Call the block once for each key/value pair in this `Hash`, passing the value as a + # parameter. Ordering guarantees are the same as {#each}. + # + # @example + # Immutable::Hash["A" => 1, "B" => 2, "C" => 3].each_value { |v| puts "v=#{v}" } + # + # v=1 + # v=3 + # v=2 + # # => Immutable::Hash["A" => 1, "B" => 2, "C" => 3] + # + # @yield [value] Once for each key/value pair. + # @return [self] + def each_value + return enum_for(:each_value) if not block_given? + @trie.each { |k,v| yield v } + self + end + + # Call the block once for each key/value pair in this `Hash`, passing the key/value + # pair as parameters. The block should return a `[key, value]` array each time. + # All the returned `[key, value]` arrays will be gathered into a new `Hash`. + # + # @example + # h = Immutable::Hash["A" => 1, "B" => 2, "C" => 3] + # h.map { |k, v| ["new-#{k}", v * v] } + # # => Hash["new-C" => 9, "new-B" => 4, "new-A" => 1] + # + # @yield [key, value] Once for each key/value pair. + # @return [Hash] + def map + return enum_for(:map) unless block_given? + return self if empty? + self.class.new(super, &@default) + end + alias collect map + + # Return a new `Hash` with all the key/value pairs for which the block returns true. + # + # @example + # h = Immutable::Hash["A" => 1, "B" => 2, "C" => 3] + # h.select { |k, v| v >= 2 } + # # => Immutable::Hash["B" => 2, "C" => 3] + # + # @yield [key, value] Once for each key/value pair. + # @yieldreturn Truthy if this pair should be present in the new `Hash`. + # @return [Hash] + def select(&block) + return enum_for(:select) unless block_given? + derive_new_hash(@trie.select(&block)) + end + alias find_all select + alias keep_if select + + # Yield `[key, value]` pairs until one is found for which the block returns true. + # Return that `[key, value]` pair. If the block never returns true, return `nil`. + # + # @example + # h = Immutable::Hash["A" => 1, "B" => 2, "C" => 3] + # h.find { |k, v| v.even? } + # # => ["B", 2] + # + # @return [Array] + # @yield [key, value] At most once for each key/value pair, until the block returns `true`. + # @yieldreturn Truthy to halt iteration and return the yielded key/value pair. + def find + return enum_for(:find) unless block_given? + each { |entry| return entry if yield entry } + nil + end + alias detect find + + # Return a new `Hash` containing all the key/value pairs from this `Hash` and + # `other`. If no block is provided, the value for entries with colliding keys + # will be that from `other`. Otherwise, the value for each duplicate key is + # determined by calling the block. + # + # `other` can be an `Immutable::Hash`, a built-in Ruby `Hash`, or any `Enumerable` + # object which yields `[key, value]` pairs. + # + # @example + # h1 = Immutable::Hash["A" => 1, "B" => 2, "C" => 3] + # h2 = Immutable::Hash["C" => 70, "D" => 80] + # h1.merge(h2) + # # => Immutable::Hash["C" => 70, "A" => 1, "D" => 80, "B" => 2] + # h1.merge(h2) { |key, v1, v2| v1 + v2 } + # # => Immutable::Hash["C" => 73, "A" => 1, "D" => 80, "B" => 2] + # + # @param other [::Enumerable] The collection to merge with + # @yieldparam key [Object] The key which was present in both collections + # @yieldparam my_value [Object] The associated value from this `Hash` + # @yieldparam other_value [Object] The associated value from the other collection + # @yieldreturn [Object] The value to associate this key with in the new `Hash` + # @return [Hash] + def merge(other) + trie = if block_given? + other.reduce(@trie) do |trie, (key, value)| + if (entry = trie.get(key)) + trie.put(key, yield(key, entry[1], value)) + else + trie.put(key, value) + end + end + else + @trie.bulk_put(other) + end + + derive_new_hash(trie) + end + + # Retrieve the value corresponding to the given key object, or use the provided + # default value or block, or otherwise raise a `KeyError`. + # + # @overload fetch(key) + # Retrieve the value corresponding to the given key, or raise a `KeyError` + # if it is not found. + # @param key [Object] The key to look up + # @overload fetch(key) { |key| ... } + + # Return a sorted {Vector} which contains all the `[key, value]` pairs in + # this `Hash` as two-element `Array`s. + # + # @overload sort + # Uses `#<=>` to determine sorted order. + # @overload sort { |(k1, v1), (k2, v2)| ... } + # Uses the block as a comparator to determine sorted order. + # + # @example + # h = Immutable::Hash["Dog" => 1, "Elephant" => 2, "Lion" => 3] + # h.sort { |(k1, v1), (k2, v2)| k1.size <=> k2.size } + # # => Immutable::Vector[["Dog", 1], ["Lion", 3], ["Elephant", 2]] + # @yield [(k1, v1), (k2, v2)] Any number of times with different pairs of key/value associations. + # @yieldreturn [Integer] Negative if the first pair should be sorted + # lower, positive if the latter pair, or 0 if equal. + # + # @see ::Enumerable#sort + # + # @return [Vector] + def sort + Vector.new(super) + end + + # Return a {Vector} which contains all the `[key, value]` pairs in this `Hash` + # as two-element Arrays. The order which the pairs will appear in is determined by + # passing each pair to the code block to obtain a sort key object, and comparing + # the sort keys using `#<=>`. + # + # @see ::Enumerable#sort_by + # + # @example + # h = Immutable::Hash["Dog" => 1, "Elephant" => 2, "Lion" => 3] + # h.sort_by { |key, value| key.size } + # # => Immutable::Vector[["Dog", 1], ["Lion", 3], ["Elephant", 2]] + # + # @yield [key, value] Once for each key/value pair. + # @yieldreturn a sort key object for the yielded pair. + # @return [Vector] + def sort_by + Vector.new(super) + end + + # Return a new `Hash` with the associations for all of the given `keys` removed. + # + # @example + # h = Immutable::Hash["A" => 1, "B" => 2, "C" => 3] + # h.except("A", "C") # => Immutable::Hash["B" => 2] + # + # @param keys [Array] The keys to remove + # @return [Hash] + def except(*keys) + keys.reduce(self) { |hash, key| hash.delete(key) } + end + + # Return a new `Hash` with only the associations for the `wanted` keys retained. + # + # @example + # h = Immutable::Hash["A" => 1, "B" => 2, "C" => 3] + # h.slice("B", "C") # => Immutable::Hash["B" => 2, "C" => 3] + # + # @param wanted [::Enumerable] The keys to retain + # @return [Hash] + def slice(*wanted) + trie = Trie.new(0) + wanted.each { |key| trie.put!(key, get(key)) if key?(key) } + self.class.alloc(trie, @default) + end + + # Return a {Vector} of the values which correspond to the `wanted` keys. + # If any of the `wanted` keys are not present in this `Hash`, `nil` will be + # placed instead, or the result of the default proc (if one is defined), + # similar to the behavior of {#get}. + # + # @example + # h = Immutable::Hash["A" => 1, "B" => 2, "C" => 3] + # h.values_at("B", "A", "D") # => Immutable::Vector[2, 1, nil] + # + # @param wanted [Array] The keys to retrieve + # @return [Vector] + def values_at(*wanted) + Vector.new(wanted.map { |key| get(key) }.freeze) + end + + # Return a {Vector} of the values which correspond to the `wanted` keys. + # If any of the `wanted` keys are not present in this `Hash`, raise `KeyError` + # exception. + # + # @example + # h = Immutable::Hash["A" => 1, "B" => 2, "C" => 3] + # h.fetch_values("C", "A") # => Immutable::Vector[3, 1] + # h.fetch_values("C", "Z") # => KeyError: key not found: "Z" + # + # @param wanted [Array] The keys to retrieve + # @return [Vector] + def fetch_values(*wanted) + array = wanted.map { |key| fetch(key) } + Vector.new(array.freeze) + end + + # Return the value of successively indexing into a nested collection. + # If any of the keys is not present, return `nil`. + # + # @example + # h = Immutable::Hash[a: 9, b: Immutable::Hash[c: 'a', d: 4], e: nil] + # h.dig(:b, :c) # => "a" + # h.dig(:b, :f) # => nil + # + # @return [Object] + def dig(key, *rest) + value = self[key] + if rest.empty? || value.nil? + value + else + value.dig(*rest) + end + end + + # Return a new {Set} containing the keys from this `Hash`. + # + # @example + # Immutable::Hash["A" => 1, "B" => 2, "C" => 3, "D" => 2].keys + # # => Immutable::Set["D", "C", "B", "A"] + # + # @return [Set] + def keys + Set.alloc(@trie) + end + + # Return a new {Vector} populated with the values from this `Hash`. + # + # @example + # Immutable::Hash["A" => 1, "B" => 2, "C" => 3, "D" => 2].values + # # => Immutable::Vector[2, 3, 2, 1] + # + # @return [Vector] + def values + Vector.new(each_value.to_a.freeze) + end + + # Return a new `Hash` created by using keys as values and values as keys. + # If there are multiple values which are equivalent (as determined by `#hash` and + # `#eql?`), only one out of each group of equivalent values will be + # retained. Which one specifically is undefined. + # + # @example + # Immutable::Hash["A" => 1, "B" => 2, "C" => 3, "D" => 2].invert + # # => Immutable::Hash[1 => "A", 3 => "C", 2 => "B"] + # + # @return [Hash] + def invert + pairs = [] + each { |k,v| pairs << [v, k] } + self.class.new(pairs, &@default) + end + + # Return a new {Vector} which is a one-dimensional flattening of this `Hash`. + # If `level` is 1, all the `[key, value]` pairs in the hash will be concatenated + # into one {Vector}. If `level` is greater than 1, keys or values which are + # themselves `Array`s or {Vector}s will be recursively flattened into the output + # {Vector}. The depth to which that flattening will be recursively applied is + # determined by `level`. + # + # As a special case, if `level` is 0, each `[key, value]` pair will be a + # separate element in the returned {Vector}. + # + # @example + # h = Immutable::Hash["A" => 1, "B" => [2, 3, 4]] + # h.flatten + # # => Immutable::Vector["A", 1, "B", [2, 3, 4]] + # h.flatten(2) + # # => Immutable::Vector["A", 1, "B", 2, 3, 4] + # + # @param level [Integer] The number of times to recursively flatten the `[key, value]` pairs in this `Hash`. + # @return [Vector] + def flatten(level = 1) + return Vector.new(self) if level == 0 + array = [] + each { |k,v| array << k; array << v } + array.flatten!(level-1) if level > 1 + Vector.new(array.freeze) + end + + # Searches through the `Hash`, comparing `obj` with each key (using `#==`). + # When a matching key is found, return the `[key, value]` pair as an array. + # Return `nil` if no match is found. + # + # @example + # Immutable::Hash["A" => 1, "B" => 2, "C" => 3].assoc("B") # => ["B", 2] + # + # @param obj [Object] The key to search for (using #==) + # @return [Array] + def assoc(obj) + each { |entry| return entry if obj == entry[0] } + nil + end + + # Searches through the `Hash`, comparing `obj` with each value (using `#==`). + # When a matching value is found, return the `[key, value]` pair as an array. + # Return `nil` if no match is found. + # + # @example + # Immutable::Hash["A" => 1, "B" => 2, "C" => 3].rassoc(2) # => ["B", 2] + # + # @param obj [Object] The value to search for (using #==) + # @return [Array] + def rassoc(obj) + each { |entry| return entry if obj == entry[1] } + nil + end + + # Searches through the `Hash`, comparing `value` with each value (using `#==`). + # When a matching value is found, return its associated key object. + # Return `nil` if no match is found. + # + # @example + # Immutable::Hash["A" => 1, "B" => 2, "C" => 3].key(2) # => "B" + # + # @param value [Object] The value to search for (using #==) + # @return [Object] + def key(value) + each { |entry| return entry[0] if value == entry[1] } + nil + end + + # Return a randomly chosen `[key, value]` pair from this `Hash`. If the hash is empty, + # return `nil`. + # + # @example + # Immutable::Hash["A" => 1, "B" => 2, "C" => 3].sample + # # => ["C", 3] + # + # @return [Array] + def sample + @trie.at(rand(size)) + end + + # Return an empty `Hash` instance, of the same class as this one. Useful if you + # have multiple subclasses of `Hash` and want to treat them polymorphically. + # Maintains the default block, if there is one. + # + # @return [Hash] + def clear + if @default + self.class.alloc(EmptyTrie, @default) + else + self.class.empty + end + end + + # Return true if `other` has the same type and contents as this `Hash`. + # + # @param other [Object] The collection to compare with + # @return [Boolean] + def eql?(other) + return true if other.equal?(self) + instance_of?(other.class) && @trie.eql?(other.instance_variable_get(:@trie)) + end + + # Return true if `other` has the same contents as this `Hash`. Will convert + # `other` to a Ruby `Hash` using `#to_hash` if necessary. + # + # @param other [Object] The object to compare with + # @return [Boolean] + def ==(other) + eql?(other) || (other.respond_to?(:to_hash) && to_hash == other.to_hash) + end + + # Return true if this `Hash` is a proper superset of `other`, which means + # all `other`'s keys are contained in this `Hash` with identical + # values, and the two hashes are not identical. + # + # @param other [Immutable::Hash] The object to compare with + # @return [Boolean] + def >(other) + self != other && self >= other + end + + # Return true if this `Hash` is a superset of `other`, which means all + # `other`'s keys are contained in this `Hash` with identical values. + # + # @param other [Immutable::Hash] The object to compare with + # @return [Boolean] + def >=(other) + other.each do |key, value| + if self[key] != value + return false + end + end + true + end + + # Return true if this `Hash` is a proper subset of `other`, which means all + # its keys are contained in `other` with the identical values, and the two + # hashes are not identical. + # + # @param other [Immutable::Hash] The object to compare with + # @return [Boolean] + def <(other) + other > self + end + + # Return true if this `Hash` is a subset of `other`, which means all its + # keys are contained in `other` with the identical values, and the two + # hashes are not identical. + # + # @param other [Immutable::Hash] The object to compare with + # @return [Boolean] + def <=(other) + other >= self + end + + # See `Object#hash`. + # @return [Integer] + def hash + keys.to_a.sort.reduce(0) do |hash, key| + (hash << 32) - hash + key.hash + get(key).hash + end + end + + # Return the contents of this `Hash` as a programmer-readable `String`. If all the + # keys and values are serializable as Ruby literal strings, the returned string can + # be passed to `eval` to reconstitute an equivalent `Hash`. The default + # block (if there is one) will be lost when doing this, however. + # + # @return [String] + def inspect + result = "#{self.class}[" + i = 0 + each do |key, val| + result << ', ' if i > 0 + result << key.inspect << ' => ' << val.inspect + i += 1 + end + result << ']' + end + + # Return `self`. Since this is an immutable object duplicates are + # equivalent. + # @return [Hash] + def dup + self + end + alias clone dup + + # Allows this `Hash` to be printed at the `pry` console, or using `pp` (from the + # Ruby standard library), in a way which takes the amount of horizontal space on + # the screen into account, and which indents nested structures to make them easier + # to read. + # + # @private + def pretty_print(pp) + pp.group(1, "#{self.class}[", ']') do + pp.breakable '' + pp.seplist(self, nil) do |key, val| + pp.group do + key.pretty_print(pp) + pp.text ' => ' + pp.group(1) do + pp.breakable '' + val.pretty_print(pp) + end + end + end + end + end + + # Convert this `Immutable::Hash` to an instance of Ruby's built-in `Hash`. + # + # @return [::Hash] + def to_hash + output = {} + each do |key, value| + output[key] = value + end + output + end + alias to_h to_hash + + # Return a `Proc` which accepts a key as an argument and returns the value. + # The `Proc` behaves like {#get} (when the key is missing, it returns nil or + # the result of the default proc). + # + # @example + # h = Immutable::Hash["A" => 1, "B" => 2, "C" => 3] + # h.to_proc.call("B") + # # => 2 + # ["A", "C", "X"].map(&h) # The & is short for .to_proc in Ruby + # # => [1, 3, nil] + # + # @return [Proc] + def to_proc + lambda { |key| get(key) } + end + + # @return [::Hash] + # @private + def marshal_dump + to_hash + end + + # @private + def marshal_load(dictionary) + @trie = Trie[dictionary] + end + + private + + # Return a new `Hash` which is derived from this one, using a modified {Trie}. + # The new `Hash` will retain the existing default block, if there is one. + # + def derive_new_hash(trie) + if trie.equal?(@trie) + self + elsif trie.empty? + if @default + self.class.alloc(EmptyTrie, @default) + else + self.class.empty + end + else + self.class.alloc(trie, @default) + end + end + end + + # The canonical empty `Hash`. Returned by `Hash[]` when + # invoked with no arguments; also returned by `Hash.empty`. Prefer using this + # one rather than creating many empty hashes using `Hash.new`. + # + # @private + EmptyHash = Immutable::Hash.empty + + + # A `Vector` is an ordered, integer-indexed collection of objects. Like + # Ruby's `Array`, `Vector` indexing starts at zero and negative indexes count + # back from the end. + # + # `Vector` has a similar interface to `Array`. The main difference is methods + # that would destructively update an `Array` (such as {#insert} or + # {#delete_at}) instead return new `Vectors` and leave the existing one + # unchanged. + # + # ### Creating New Vectors + # + # Immutable::Vector.new([:first, :second, :third]) + # Immutable::Vector[1, 2, 3, 4, 5] + # + # ### Retrieving Items from Vectors + # + # vector = Immutable::Vector[1, 2, 3, 4, 5] + # + # vector[0] # => 1 + # vector[-1] # => 5 + # vector[0,3] # => Immutable::Vector[1, 2, 3] + # vector[1..-1] # => Immutable::Vector[2, 3, 4, 5] + # vector.first # => 1 + # vector.last # => 5 + # + # ### Creating Modified Vectors + # + # vector.add(6) # => Immutable::Vector[1, 2, 3, 4, 5, 6] + # vector.insert(1, :a, :b) # => Immutable::Vector[1, :a, :b, 2, 3, 4, 5] + # vector.delete_at(2) # => Immutable::Vector[1, 2, 4, 5] + # vector + [6, 7] # => Immutable::Vector[1, 2, 3, 4, 5, 6, 7] + # + class Vector + include Immutable::Enumerable + + # @private + BLOCK_SIZE = 32 + # @private + INDEX_MASK = BLOCK_SIZE - 1 + # @private + BITS_PER_LEVEL = 5 + + # Return the number of items in this `Vector` + # @return [Integer] + attr_reader :size + alias length size + + class << self + # Create a new `Vector` populated with the given items. + # @return [Vector] + def [](*items) + new(items.freeze) + end + + # Return an empty `Vector`. If used on a subclass, returns an empty instance + # of that class. + # + # @return [Vector] + def empty + @empty ||= new + end + + # "Raw" allocation of a new `Vector`. Used internally to create a new + # instance quickly after building a modified trie. + # + # @return [Vector] + # @private + def alloc(root, size, levels) + obj = allocate + obj.instance_variable_set(:@root, root) + obj.instance_variable_set(:@size, size) + obj.instance_variable_set(:@levels, levels) + obj.freeze + end + end + + def initialize(items=[].freeze) + items = items.to_a + if items.size <= 32 + items = items.dup.freeze if !items.frozen? + @root, @size, @levels = items, items.size, 0 + else + root, size, levels = items, items.size, 0 + while root.size > 32 + root = root.each_slice(32).to_a + levels += 1 + end + @root, @size, @levels = root.freeze, size, levels + end + freeze + end + + # Return `true` if this `Vector` contains no items. + # + # @return [Boolean] + def empty? + @size == 0 + end + + # Return the first item in the `Vector`. If the vector is empty, return `nil`. + # + # @example + # Immutable::Vector["A", "B", "C"].first # => "A" + # + # @return [Object] + def first + get(0) + end + + # Return the last item in the `Vector`. If the vector is empty, return `nil`. + # + # @example + # Immutable::Vector["A", "B", "C"].last # => "C" + # + # @return [Object] + def last + get(-1) + end + + # Return a new `Vector` with `item` added after the last occupied position. + # + # @example + # Immutable::Vector[1, 2].add(99) # => Immutable::Vector[1, 2, 99] + # + # @param item [Object] The object to insert at the end of the vector + # @return [Vector] + def add(item) + update_root(@size, item) + end + alias << add + alias push add + + # Return a new `Vector` with a new value at the given `index`. If `index` + # is greater than the length of the vector, the returned vector will be + # padded with `nil`s to the correct size. + # + # @overload set(index, item) + # Return a new `Vector` with the item at `index` replaced by `item`. + # + # @param item [Object] The object to insert into that position + # @example + # Immutable::Vector[1, 2, 3, 4].set(2, 99) + # # => Immutable::Vector[1, 2, 99, 4] + # Immutable::Vector[1, 2, 3, 4].set(-1, 99) + # # => Immutable::Vector[1, 2, 3, 99] + # Immutable::Vector[].set(2, 99) + # # => Immutable::Vector[nil, nil, 99] + # + # @overload set(index) + # Return a new `Vector` with the item at `index` replaced by the return + # value of the block. + # + # @yield (existing) Once with the existing value at the given `index`. + # @example + # Immutable::Vector[1, 2, 3, 4].set(2) { |v| v * 10 } + # # => Immutable::Vector[1, 2, 30, 4] + # + # @param index [Integer] The index to update. May be negative. + # @return [Vector] + def set(index, item = yield(get(index))) + raise IndexError, "index #{index} outside of vector bounds" if index < -@size + index += @size if index < 0 + if index > @size + suffix = Array.new(index - @size, nil) + suffix << item + replace_suffix(@size, suffix) + else + update_root(index, item) + end + end + + # Return a new `Vector` with a deeply nested value modified to the result + # of the given code block. When traversing the nested `Vector`s and + # `Hash`es, non-existing keys are created with empty `Hash` values. + # + # The code block receives the existing value of the deeply nested key (or + # `nil` if it doesn't exist). This is useful for "transforming" the value + # associated with a certain key. + # + # Note that the original `Vector` and sub-`Vector`s and sub-`Hash`es are + # left unmodified; new data structure copies are created along the path + # wherever needed. + # + # @example + # v = Immutable::Vector[123, 456, 789, Immutable::Hash["a" => Immutable::Vector[5, 6, 7]]] + # v.update_in(3, "a", 1) { |value| value + 9 } + # # => Immutable::Vector[123, 456, 789, Immutable::Hash["a" => Immutable::Vector[5, 15, 7]]] + # + # @param key_path [Object(s)] List of keys which form the path to the key to be modified + # @yield [value] The previously stored value + # @yieldreturn [Object] The new value to store + # @return [Vector] + def update_in(*key_path, &block) + if key_path.empty? + raise ArgumentError, 'must have at least one key in path' + end + key = key_path[0] + if key_path.size == 1 + new_value = block.call(get(key)) + else + value = fetch(key, Immutable::EmptyHash) + new_value = value.update_in(*key_path[1..-1], &block) + end + set(key, new_value) + end + + # Retrieve the item at `index`. If there is none (either the provided index + # is too high or too low), return `nil`. + # + # @example + # v = Immutable::Vector["A", "B", "C", "D"] + # v.get(2) # => "C" + # v.get(-1) # => "D" + # v.get(4) # => nil + # + # @param index [Integer] The index to retrieve + # @return [Object] + def get(index) + return nil if @size == 0 + index += @size if index < 0 + return nil if index >= @size || index < 0 + leaf_node_for(@root, @levels * BITS_PER_LEVEL, index)[index & INDEX_MASK] + end + alias at get + + # Retrieve the value at `index` with optional default. + # + # @overload fetch(index) + # Retrieve the value at the given index, or raise an `IndexError` if not + # found. + # + # @param index [Integer] The index to look up + # @raise [IndexError] if index does not exist + # @example + # v = Immutable::Vector["A", "B", "C", "D"] + # v.fetch(2) # => "C" + # v.fetch(-1) # => "D" + # v.fetch(4) # => IndexError: index 4 outside of vector bounds + # + # @overload fetch(index) { |index| ... } + # Retrieve the value at the given index, or return the result of yielding + # the block if not found. + # + # @yield Once if the index is not found. + # @yieldparam [Integer] index The index which does not exist + # @yieldreturn [Object] Default value to return + # @param index [Integer] The index to look up + # @example + # v = Immutable::Vector["A", "B", "C", "D"] + # v.fetch(2) { |i| i * i } # => "C" + # v.fetch(4) { |i| i * i } # => 16 + # + # @overload fetch(index, default) + # Retrieve the value at the given index, or return the provided `default` + # value if not found. + # + # @param index [Integer] The index to look up + # @param default [Object] Object to return if the key is not found + # @example + # v = Immutable::Vector["A", "B", "C", "D"] + # v.fetch(2, "Z") # => "C" + # v.fetch(4, "Z") # => "Z" + # + # @return [Object] + def fetch(index, default = (missing_default = true)) + if index >= -@size && index < @size + get(index) + elsif block_given? + yield(index) + elsif !missing_default + default + else + raise IndexError, "index #{index} outside of vector bounds" + end + end + + # Return the value of successively indexing into a nested collection. + # If any of the keys is not present, return `nil`. + # + # @example + # v = Immutable::Vector[9, Immutable::Hash[c: 'a', d: 4]] + # v.dig(1, :c) # => "a" + # v.dig(1, :f) # => nil + # + # @return [Object] + def dig(key, *rest) + value = self[key] + if rest.empty? || value.nil? + value + else + value.dig(*rest) + end + end + + # Return specific objects from the `Vector`. All overloads return `nil` if + # the starting index is out of range. + # + # @overload vector.slice(index) + # Returns a single object at the given `index`. If `index` is negative, + # count backwards from the end. + # + # @param index [Integer] The index to retrieve. May be negative. + # @return [Object] + # @example + # v = Immutable::Vector["A", "B", "C", "D", "E", "F"] + # v[2] # => "C" + # v[-1] # => "F" + # v[6] # => nil + # + # @overload vector.slice(index, length) + # Return a subvector starting at `index` and continuing for `length` + # elements or until the end of the `Vector`, whichever occurs first. + # + # @param start [Integer] The index to start retrieving items from. May be + # negative. + # @param length [Integer] The number of items to retrieve. + # @return [Vector] + # @example + # v = Immutable::Vector["A", "B", "C", "D", "E", "F"] + # v[2, 3] # => Immutable::Vector["C", "D", "E"] + # v[-2, 3] # => Immutable::Vector["E", "F"] + # v[20, 1] # => nil + # + # @overload vector.slice(index..end) + # Return a subvector starting at `index` and continuing to index + # `end` or the end of the `Vector`, whichever occurs first. + # + # @param range [Range] The range of indices to retrieve. + # @return [Vector] + # @example + # v = Immutable::Vector["A", "B", "C", "D", "E", "F"] + # v[2..3] # => Immutable::Vector["C", "D"] + # v[-2..100] # => Immutable::Vector["E", "F"] + # v[20..21] # => nil + def slice(arg, length = (missing_length = true)) + if missing_length + if arg.is_a?(Range) + from, to = arg.begin, arg.end + from += @size if from < 0 + to += @size if to < 0 + to += 1 if !arg.exclude_end? + length = to - from + length = 0 if length < 0 + subsequence(from, length) + else + get(arg) + end + else + arg += @size if arg < 0 + subsequence(arg, length) + end + end + alias [] slice + + # Return a new `Vector` with the given values inserted before the element + # at `index`. If `index` is greater than the current length, `nil` values + # are added to pad the `Vector` to the required size. + # + # @example + # Immutable::Vector["A", "B", "C", "D"].insert(2, "X", "Y", "Z") + # # => Immutable::Vector["A", "B", "X", "Y", "Z", "C", "D"] + # Immutable::Vector[].insert(2, "X", "Y", "Z") + # # => Immutable::Vector[nil, nil, "X", "Y", "Z"] + # + # @param index [Integer] The index where the new items should go + # @param items [Array] The items to add + # @return [Vector] + # @raise [IndexError] if index exceeds negative range. + def insert(index, *items) + raise IndexError if index < -@size + index += @size if index < 0 + + if index < @size + suffix = flatten_suffix(@root, @levels * BITS_PER_LEVEL, index, []) + suffix.unshift(*items) + elsif index == @size + suffix = items + else + suffix = Array.new(index - @size, nil).concat(items) + index = @size + end + + replace_suffix(index, suffix) + end + + # Return a new `Vector` with the element at `index` removed. If the given `index` + # does not exist, return `self`. + # + # @example + # Immutable::Vector["A", "B", "C", "D"].delete_at(2) + # # => Immutable::Vector["A", "B", "D"] + # + # @param index [Integer] The index to remove + # @return [Vector] + def delete_at(index) + return self if index >= @size || index < -@size + index += @size if index < 0 + + suffix = flatten_suffix(@root, @levels * BITS_PER_LEVEL, index, []) + replace_suffix(index, suffix.tap(&:shift)) + end + + # Return a new `Vector` with the last element removed. Return `self` if + # empty. + # + # @example + # Immutable::Vector["A", "B", "C"].pop # => Immutable::Vector["A", "B"] + # + # @return [Vector] + def pop + return self if @size == 0 + replace_suffix(@size-1, []) + end + + # Return a new `Vector` with `object` inserted before the first element, + # moving the other elements upwards. + # + # @example + # Immutable::Vector["A", "B"].unshift("Z") + # # => Immutable::Vector["Z", "A", "B"] + # + # @param object [Object] The value to prepend + # @return [Vector] + def unshift(object) + insert(0, object) + end + + # Return a new `Vector` with the first element removed. If empty, return + # `self`. + # + # @example + # Immutable::Vector["A", "B", "C"].shift # => Immutable::Vector["B", "C"] + # + # @return [Vector] + def shift + delete_at(0) + end + + # Call the given block once for each item in the vector, passing each + # item from first to last successively to the block. If no block is given, + # an `Enumerator` is returned instead. + # + # @example + # Immutable::Vector["A", "B", "C"].each { |e| puts "Element: #{e}" } + # + # Element: A + # Element: B + # Element: C + # # => Immutable::Vector["A", "B", "C"] + # + # @return [self, Enumerator] + def each(&block) + return to_enum unless block_given? + traverse_depth_first(@root, @levels, &block) + self + end + + # Call the given block once for each item in the vector, from last to + # first. + # + # @example + # Immutable::Vector["A", "B", "C"].reverse_each { |e| puts "Element: #{e}" } + # + # Element: C + # Element: B + # Element: A + # + # @return [self] + def reverse_each(&block) + return enum_for(:reverse_each) unless block_given? + reverse_traverse_depth_first(@root, @levels, &block) + self + end + + # Return a new `Vector` containing all elements for which the given block returns + # true. + # + # @example + # Immutable::Vector["Bird", "Cow", "Elephant"].select { |e| e.size >= 4 } + # # => Immutable::Vector["Bird", "Elephant"] + # + # @return [Vector] + # @yield [element] Once for each element. + def select + return enum_for(:select) unless block_given? + reduce(self.class.empty) { |vector, item| yield(item) ? vector.add(item) : vector } + end + alias find_all select + alias keep_if select + + # Return a new `Vector` with all items which are equal to `obj` removed. + # `#==` is used for checking equality. + # + # @example + # Immutable::Vector["C", "B", "A", "B"].delete("B") # => Immutable::Vector["C", "A"] + # + # @param obj [Object] The object to remove (every occurrence) + # @return [Vector] + def delete(obj) + select { |item| item != obj } + end + + # Invoke the given block once for each item in the vector, and return a new + # `Vector` containing the values returned by the block. If no block is + # provided, return an enumerator. + # + # @example + # Immutable::Vector[3, 2, 1].map { |e| e * e } # => Immutable::Vector[9, 4, 1] + # + # @return [Vector, Enumerator] + def map + return enum_for(:map) if not block_given? + return self if empty? + self.class.new(super) + end + alias collect map + + # Return a new `Vector` with the concatenated results of running the block once + # for every element in this `Vector`. + # + # @example + # Immutable::Vector[1, 2, 3].flat_map { |x| [x, -x] } + # # => Immutable::Vector[1, -1, 2, -2, 3, -3] + # + # @return [Vector] + def flat_map + return enum_for(:flat_map) if not block_given? + return self if empty? + self.class.new(super) + end + + # Return a new `Vector` with the same elements as this one, but randomly permuted. + # + # @example + # Immutable::Vector[1, 2, 3, 4].shuffle # => Immutable::Vector[4, 1, 3, 2] + # + # @return [Vector] + def shuffle + self.class.new(((array = to_a).frozen? ? array.shuffle : array.shuffle!).freeze) + end + + # Return a new `Vector` with no duplicate elements, as determined by `#hash` and + # `#eql?`. For each group of equivalent elements, only the first will be retained. + # + # @example + # Immutable::Vector["A", "B", "C", "B"].uniq # => Immutable::Vector["A", "B", "C"] + # Immutable::Vector["a", "A", "b"].uniq(&:upcase) # => Immutable::Vector["a", "b"] + # + # @return [Vector] + def uniq(&block) + array = to_a + if array.frozen? + self.class.new(array.uniq(&block).freeze) + elsif array.uniq!(&block) # returns nil if no changes were made + self.class.new(array.freeze) + else + self + end + end + + # Return a new `Vector` with the same elements as this one, but in reverse order. + # + # @example + # Immutable::Vector["A", "B", "C"].reverse # => Immutable::Vector["C", "B", "A"] + # + # @return [Vector] + def reverse + self.class.new(((array = to_a).frozen? ? array.reverse : array.reverse!).freeze) + end + + # Return a new `Vector` with the same elements, but rotated so that the one at + # index `count` is the first element of the new vector. If `count` is positive, + # the elements will be shifted left, and those shifted past the lowest position + # will be moved to the end. If `count` is negative, the elements will be shifted + # right, and those shifted past the last position will be moved to the beginning. + # + # @example + # v = Immutable::Vector["A", "B", "C", "D", "E", "F"] + # v.rotate(2) # => Immutable::Vector["C", "D", "E", "F", "A", "B"] + # v.rotate(-1) # => Immutable::Vector["F", "A", "B", "C", "D", "E"] + # + # @param count [Integer] The number of positions to shift items by + # @return [Vector] + def rotate(count = 1) + return self if (count % @size) == 0 + self.class.new(((array = to_a).frozen? ? array.rotate(count) : array.rotate!(count)).freeze) + end + + # Return a new `Vector` with all nested vectors and arrays recursively "flattened + # out". That is, their elements inserted into the new `Vector` in the place where + # the nested array/vector originally was. If an optional `level` argument is + # provided, the flattening will only be done recursively that number of times. + # A `level` of 0 means not to flatten at all, 1 means to only flatten nested + # arrays/vectors which are directly contained within this `Vector`. + # + # @example + # v = Immutable::Vector["A", Immutable::Vector["B", "C", Immutable::Vector["D"]]] + # v.flatten(1) + # # => Immutable::Vector["A", "B", "C", Immutable::Vector["D"]] + # v.flatten + # # => Immutable::Vector["A", "B", "C", "D"] + # + # @param level [Integer] The depth to which flattening should be applied + # @return [Vector] + def flatten(level = -1) + return self if level == 0 + array = to_a + if array.frozen? + self.class.new(array.flatten(level).freeze) + elsif array.flatten!(level) # returns nil if no changes were made + self.class.new(array.freeze) + else + self + end + end + + # Return a new `Vector` built by concatenating this one with `other`. `other` + # can be any object which is convertible to an `Array` using `#to_a`. + # + # @example + # Immutable::Vector["A", "B", "C"] + ["D", "E"] + # # => Immutable::Vector["A", "B", "C", "D", "E"] + # + # @param other [Enumerable] The collection to concatenate onto this vector + # @return [Vector] + def +(other) + other = other.to_a + other = other.dup if other.frozen? + replace_suffix(@size, other) + end + alias concat + + + # Combine two vectors by "zipping" them together. `others` should be arrays + # and/or vectors. The corresponding elements from this `Vector` and each of + # `others` (that is, the elements with the same indices) will be gathered + # into arrays. + # + # If `others` contains fewer elements than this vector, `nil` will be used + # for padding. + # + # @overload zip(*others) + # Return a new vector containing the new arrays. + # + # @return [Vector] + # + # @overload zip(*others) + # @yield [pair] once for each array + # @return [nil] + # + # @example + # v1 = Immutable::Vector["A", "B", "C"] + # v2 = Immutable::Vector[1, 2] + # v1.zip(v2) + # # => Immutable::Vector[["A", 1], ["B", 2], ["C", nil]] + # + # @param others [Array] The arrays/vectors to zip together with this one + # @return [Vector] + def zip(*others) + if block_given? + super + else + self.class.new(super) + end + end + + # Return a new `Vector` with the same items, but sorted. + # + # @overload sort + # Compare elements with their natural sort key (`#<=>`). + # + # @example + # Immutable::Vector["Elephant", "Dog", "Lion"].sort + # # => Immutable::Vector["Dog", "Elephant", "Lion"] + # + # @overload sort + # Uses the block as a comparator to determine sorted order. + # + # @yield [a, b] Any number of times with different pairs of elements. + # @yieldreturn [Integer] Negative if the first element should be sorted + # lower, positive if the latter element, or 0 if + # equal. + # @example + # Immutable::Vector["Elephant", "Dog", "Lion"].sort { |a,b| a.size <=> b.size } + # # => Immutable::Vector["Dog", "Lion", "Elephant"] + # + # @return [Vector] + def sort + self.class.new(super) + end + + # Return a new `Vector` with the same items, but sorted. The sort order is + # determined by mapping the items through the given block to obtain sort + # keys, and then sorting the keys according to their natural sort order + # (`#<=>`). + # + # @yield [element] Once for each element. + # @yieldreturn a sort key object for the yielded element. + # @example + # Immutable::Vector["Elephant", "Dog", "Lion"].sort_by { |e| e.size } + # # => Immutable::Vector["Dog", "Lion", "Elephant"] + # + # @return [Vector] + def sort_by + self.class.new(super) + end + + # Drop the first `n` elements and return the rest in a new `Vector`. + # + # @example + # Immutable::Vector["A", "B", "C", "D", "E", "F"].drop(2) + # # => Immutable::Vector["C", "D", "E", "F"] + # + # @param n [Integer] The number of elements to remove + # @return [Vector] + # @raise ArgumentError if `n` is negative. + def drop(n) + return self if n == 0 + return self.class.empty if n >= @size + raise ArgumentError, 'attempt to drop negative size' if n < 0 + self.class.new(flatten_suffix(@root, @levels * BITS_PER_LEVEL, n, [])) + end + + # Return only the first `n` elements in a new `Vector`. + # + # @example + # Immutable::Vector["A", "B", "C", "D", "E", "F"].take(4) + # # => Immutable::Vector["A", "B", "C", "D"] + # + # @param n [Integer] The number of elements to retain + # @return [Vector] + def take(n) + return self if n >= @size + self.class.new(super) + end + + # Drop elements up to, but not including, the first element for which the + # block returns `nil` or `false`. Gather the remaining elements into a new + # `Vector`. If no block is given, an `Enumerator` is returned instead. + # + # @example + # Immutable::Vector[1, 3, 5, 7, 6, 4, 2].drop_while { |e| e < 5 } + # # => Immutable::Vector[5, 7, 6, 4, 2] + # + # @return [Vector, Enumerator] + def drop_while + return enum_for(:drop_while) if not block_given? + self.class.new(super) + end + + # Gather elements up to, but not including, the first element for which the + # block returns `nil` or `false`, and return them in a new `Vector`. If no block + # is given, an `Enumerator` is returned instead. + # + # @example + # Immutable::Vector[1, 3, 5, 7, 6, 4, 2].take_while { |e| e < 5 } + # # => Immutable::Vector[1, 3] + # + # @return [Vector, Enumerator] + def take_while + return enum_for(:take_while) if not block_given? + self.class.new(super) + end + + # Repetition. Return a new `Vector` built by concatenating `times` copies + # of this one together. + # + # @example + # Immutable::Vector["A", "B"] * 3 + # # => Immutable::Vector["A", "B", "A", "B", "A", "B"] + # + # @param times [Integer] The number of times to repeat the elements in this vector + # @return [Vector] + def *(times) + return self.class.empty if times == 0 + return self if times == 1 + result = (to_a * times) + result.is_a?(Array) ? self.class.new(result) : result + end + + # Replace a range of indexes with the given object. + # + # @overload fill(object) + # Return a new `Vector` of the same size, with every index set to + # `object`. + # + # @param [Object] object Fill value. + # @example + # Immutable::Vector["A", "B", "C", "D", "E", "F"].fill("Z") + # # => Immutable::Vector["Z", "Z", "Z", "Z", "Z", "Z"] + # + # @overload fill(object, index) + # Return a new `Vector` with all indexes from `index` to the end of the + # vector set to `object`. + # + # @param [Object] object Fill value. + # @param [Integer] index Starting index. May be negative. + # @example + # Immutable::Vector["A", "B", "C", "D", "E", "F"].fill("Z", 3) + # # => Immutable::Vector["A", "B", "C", "Z", "Z", "Z"] + # + # @overload fill(object, index, length) + # Return a new `Vector` with `length` indexes, beginning from `index`, + # set to `object`. Expands the `Vector` if `length` would extend beyond + # the current length. + # + # @param [Object] object Fill value. + # @param [Integer] index Starting index. May be negative. + # @param [Integer] length + # @example + # Immutable::Vector["A", "B", "C", "D", "E", "F"].fill("Z", 3, 2) + # # => Immutable::Vector["A", "B", "C", "Z", "Z", "F"] + # Immutable::Vector["A", "B"].fill("Z", 1, 5) + # # => Immutable::Vector["A", "Z", "Z", "Z", "Z", "Z"] + # + # @return [Vector] + # @raise [IndexError] if index is out of negative range. + def fill(object, index = 0, length = nil) + raise IndexError if index < -@size + index += @size if index < 0 + length ||= @size - index # to the end of the array, if no length given + + if index < @size + suffix = flatten_suffix(@root, @levels * BITS_PER_LEVEL, index, []) + suffix.fill(object, 0, length) + elsif index == @size + suffix = Array.new(length, object) + else + suffix = Array.new(index - @size, nil).concat(Array.new(length, object)) + index = @size + end + + replace_suffix(index, suffix) + end + + # When invoked with a block, yields all combinations of length `n` of items + # from the `Vector`, and then returns `self`. There is no guarantee about + # which order the combinations will be yielded. + # + # If no block is given, an `Enumerator` is returned instead. + # + # @example + # v = Immutable::Vector[5, 6, 7, 8] + # v.combination(3) { |c| puts "Combination: #{c}" } + # + # Combination: [5, 6, 7] + # Combination: [5, 6, 8] + # Combination: [5, 7, 8] + # Combination: [6, 7, 8] + # #=> Immutable::Vector[5, 6, 7, 8] + # + # @return [self, Enumerator] + def combination(n) + return enum_for(:combination, n) if not block_given? + return self if n < 0 || @size < n + if n == 0 + yield [] + elsif n == 1 + each { |item| yield [item] } + elsif n == @size + yield to_a + else + combos = lambda do |result,index,remaining| + while @size - index > remaining + if remaining == 1 + yield result.dup << get(index) + else + combos[result.dup << get(index), index+1, remaining-1] + end + index += 1 + end + index.upto(@size-1) { |i| result << get(i) } + yield result + end + combos[[], 0, n] + end + self + end + + # When invoked with a block, yields all repeated combinations of length `n` of + # items from the `Vector`, and then returns `self`. A "repeated combination" is + # one in which any item from the `Vector` can appear consecutively any number of + # times. + # + # There is no guarantee about which order the combinations will be yielded in. + # + # If no block is given, an `Enumerator` is returned instead. + # + # @example + # v = Immutable::Vector[5, 6, 7, 8] + # v.repeated_combination(2) { |c| puts "Combination: #{c}" } + # + # Combination: [5, 5] + # Combination: [5, 6] + # Combination: [5, 7] + # Combination: [5, 8] + # Combination: [6, 6] + # Combination: [6, 7] + # Combination: [6, 8] + # Combination: [7, 7] + # Combination: [7, 8] + # Combination: [8, 8] + # # => Immutable::Vector[5, 6, 7, 8] + # + # @return [self, Enumerator] + def repeated_combination(n) + return enum_for(:repeated_combination, n) if not block_given? + if n < 0 + # yield nothing + elsif n == 0 + yield [] + elsif n == 1 + each { |item| yield [item] } + elsif @size == 0 + # yield nothing + else + combos = lambda do |result,index,remaining| + while index < @size-1 + if remaining == 1 + yield result.dup << get(index) + else + combos[result.dup << get(index), index, remaining-1] + end + index += 1 + end + item = get(index) + remaining.times { result << item } + yield result + end + combos[[], 0, n] + end + self + end + + # Yields all permutations of length `n` of items from the `Vector`, and then + # returns `self`. If no length `n` is specified, permutations of all elements + # will be yielded. + # + # There is no guarantee about which order the permutations will be yielded in. + # + # If no block is given, an `Enumerator` is returned instead. + # + # @example + # v = Immutable::Vector[5, 6, 7] + # v.permutation(2) { |p| puts "Permutation: #{p}" } + # + # Permutation: [5, 6] + # Permutation: [5, 7] + # Permutation: [6, 5] + # Permutation: [6, 7] + # Permutation: [7, 5] + # Permutation: [7, 6] + # # => Immutable::Vector[5, 6, 7] + # + # @return [self, Enumerator] + def permutation(n = @size) + return enum_for(:permutation, n) if not block_given? + if n < 0 || @size < n + # yield nothing + elsif n == 0 + yield [] + elsif n == 1 + each { |item| yield [item] } + else + used, result = [], [] + perms = lambda do |index| + 0.upto(@size-1) do |i| + next if used[i] + result[index] = get(i) + if index < n-1 + used[i] = true + perms[index+1] + used[i] = false + else + yield result.dup + end + end + end + perms[0] + end + self + end + + # When invoked with a block, yields all repeated permutations of length `n` of + # items from the `Vector`, and then returns `self`. A "repeated permutation" is + # one where any item from the `Vector` can appear any number of times, and in + # any position (not just consecutively) + # + # If no length `n` is specified, permutations of all elements will be yielded. + # There is no guarantee about which order the permutations will be yielded in. + # + # If no block is given, an `Enumerator` is returned instead. + # + # @example + # v = Immutable::Vector[5, 6, 7] + # v.repeated_permutation(2) { |p| puts "Permutation: #{p}" } + # + # Permutation: [5, 5] + # Permutation: [5, 6] + # Permutation: [5, 7] + # Permutation: [6, 5] + # Permutation: [6, 6] + # Permutation: [6, 7] + # Permutation: [7, 5] + # Permutation: [7, 6] + # Permutation: [7, 7] + # # => Immutable::Vector[5, 6, 7] + # + # @return [self, Enumerator] + def repeated_permutation(n = @size) + return enum_for(:repeated_permutation, n) if not block_given? + if n < 0 + # yield nothing + elsif n == 0 + yield [] + elsif n == 1 + each { |item| yield [item] } + else + result = [] + perms = lambda do |index| + 0.upto(@size-1) do |i| + result[index] = get(i) + if index < n-1 + perms[index+1] + else + yield result.dup + end + end + end + perms[0] + end + self + end + + # Cartesian product or multiplication. + # + # @overload product(*vectors) + # Return a `Vector` of all combinations of elements from this `Vector` and each + # of the given vectors or arrays. The length of the returned `Vector` is the product + # of `self.size` and the size of each argument vector or array. + # @example + # v1 = Immutable::Vector[1, 2, 3] + # v2 = Immutable::Vector["A", "B"] + # v1.product(v2) + # # => [[1, "A"], [1, "B"], [2, "A"], [2, "B"], [3, "A"], [3, "B"]] + # @overload product + # Return the result of multiplying all the items in this `Vector` together. + # + # @example + # Immutable::Vector[1, 2, 3, 4, 5].product # => 120 + # + # @return [Vector] + def product(*vectors) + # if no vectors passed, return "product" as in result of multiplying all items + return super if vectors.empty? + + vectors.unshift(self) + + if vectors.any?(&:empty?) + return block_given? ? self : [] + end + + counters = Array.new(vectors.size, 0) + + bump_counters = lambda do + i = vectors.size-1 + counters[i] += 1 + while counters[i] == vectors[i].size + counters[i] = 0 + i -= 1 + return true if i == -1 # we are done + counters[i] += 1 + end + false # not done yet + end + build_array = lambda do + array = [] + counters.each_with_index { |index,i| array << vectors[i][index] } + array + end + + if block_given? + loop do + yield build_array[] + return self if bump_counters[] + end + else + result = [] + loop do + result << build_array[] + return result if bump_counters[] + end + end + end + + # Assume all elements are vectors or arrays and transpose the rows and columns. + # In other words, take the first element of each nested vector/array and gather + # them together into a new `Vector`. Do likewise for the second, third, and so on + # down to the end of each nested vector/array. Gather all the resulting `Vectors` + # into a new `Vector` and return it. + # + # This operation is closely related to {#zip}. The result is almost the same as + # calling {#zip} on the first nested vector/array with the others supplied as + # arguments. + # + # @example + # Immutable::Vector[["A", 10], ["B", 20], ["C", 30]].transpose + # # => Immutable::Vector[Immutable::Vector["A", "B", "C"], Immutable::Vector[10, 20, 30]] + # + # @return [Vector] + # @raise [IndexError] if elements are not of the same size. + # @raise [TypeError] if an element does not respond to #size and #[] + def transpose + return self.class.empty if empty? + result = Array.new(first.size) { [] } + + 0.upto(@size-1) do |i| + source = get(i) + if source.size != result.size + raise IndexError, "element size differs (#{source.size} should be #{result.size})" + end + + 0.upto(result.size-1) do |j| + result[j].push(source[j]) + end + end + + result.map! { |a| self.class.new(a) } + self.class.new(result) + rescue NoMethodError + if any? { |x| !x.respond_to?(:size) || !x.respond_to?(:[]) } + bad = find { |x| !x.respond_to?(:size) || !x.respond_to?(:[]) } + raise TypeError, "'#{bad.inspect}' must respond to #size and #[] to be transposed" + else + raise + end + end + + # Finds a value from this `Vector` which meets the condition defined by the + # provided block, using a binary search. The vector must already be sorted + # with respect to the block. See Ruby's `Array#bsearch` for details, + # behaviour is equivalent. + # + # @example + # v = Immutable::Vector[1, 3, 5, 7, 9, 11, 13] + # # Block returns true/false for exact element match: + # v.bsearch { |e| e > 4 } # => 5 + # # Block returns number to match an element in 4 <= e <= 7: + # v.bsearch { |e| 1 - e / 4 } # => 7 + # + # @yield Once for at most `log n` elements, where `n` is the size of the + # vector. The exact elements and ordering are undefined. + # @yieldreturn [Boolean] `true` if this element matches the criteria, `false` otherwise. + # @yieldreturn [Integer] See `Array#bsearch` for details. + # @yieldparam [Object] element element to be evaluated + # @return [Object] The matched element, or `nil` if none found. + # @raise TypeError if the block returns a non-numeric, non-boolean, non-nil + # value. + def bsearch + return enum_for(:bsearch) if not block_given? + low, high, result = 0, @size, nil + while low < high + mid = (low + ((high - low) >> 1)) + val = get(mid) + v = yield val + if v.is_a? Numeric + if v == 0 + return val + elsif v > 0 + high = mid + else + low = mid + 1 + end + elsif v == true + result = val + high = mid + elsif !v + low = mid + 1 + else + raise TypeError, "wrong argument type #{v.class} (must be numeric, true, false, or nil)" + end + end + result + end + + # Return an empty `Vector` instance, of the same class as this one. Useful if you + # have multiple subclasses of `Vector` and want to treat them polymorphically. + # + # @return [Vector] + def clear + self.class.empty + end + + # Return a randomly chosen item from this `Vector`. If the vector is empty, return `nil`. + # + # @example + # Immutable::Vector[1, 2, 3, 4, 5].sample # => 2 + # + # @return [Object] + def sample + get(rand(@size)) + end + + # Return a new `Vector` with only the elements at the given `indices`, in the + # order specified by `indices`. If any of the `indices` do not exist, `nil`s will + # appear in their places. + # + # @example + # v = Immutable::Vector["A", "B", "C", "D", "E", "F"] + # v.values_at(2, 4, 5) # => Immutable::Vector["C", "E", "F"] + # + # @param indices [Array] The indices to retrieve and gather into a new `Vector` + # @return [Vector] + def values_at(*indices) + self.class.new(indices.map { |i| get(i) }.freeze) + end + + # Find the index of an element, starting from the end of the vector. + # Returns `nil` if no element is found. + # + # @overload rindex(obj) + # Return the index of the last element which is `#==` to `obj`. + # + # @example + # v = Immutable::Vector[7, 8, 9, 7, 8, 9] + # v.rindex(8) # => 4 + # + # @overload rindex + # Return the index of the last element for which the block returns true. + # + # @yield [element] Once for each element, last to first, until the block + # returns true. + # @example + # v = Immutable::Vector[7, 8, 9, 7, 8, 9] + # v.rindex { |e| e.even? } # => 4 + # + # @return [Integer] + def rindex(obj = (missing_arg = true)) + i = @size - 1 + if missing_arg + if block_given? + reverse_each { |item| return i if yield item; i -= 1 } + nil + else + enum_for(:rindex) + end + else + reverse_each { |item| return i if item == obj; i -= 1 } + nil + end + end + + # Assumes all elements are nested, indexable collections, and searches through them, + # comparing `obj` with the first element of each nested collection. Return the + # first nested collection which matches, or `nil` if none is found. + # Behaviour is undefined when elements do not meet assumptions (i.e. are + # not indexable collections). + # + # @example + # v = Immutable::Vector[["A", 10], ["B", 20], ["C", 30]] + # v.assoc("B") # => ["B", 20] + # + # @param obj [Object] The object to search for + # @return [Object] + def assoc(obj) + each do |array| + next if !array.respond_to?(:[]) + return array if obj == array[0] + end + nil + end + + # Assumes all elements are nested, indexable collections, and searches through them, + # comparing `obj` with the second element of each nested collection. Return + # the first nested collection which matches, or `nil` if none is found. + # Behaviour is undefined when elements do not meet assumptions (i.e. are + # not indexable collections). + # + # @example + # v = Immutable::Vector[["A", 10], ["B", 20], ["C", 30]] + # v.rassoc(20) # => ["B", 20] + # + # @param obj [Object] The object to search for + # @return [Object] + def rassoc(obj) + each do |array| + next if !array.respond_to?(:[]) + return array if obj == array[1] + end + nil + end + + # Return an `Array` with the same elements, in the same order. The returned + # `Array` may or may not be frozen. + # + # @return [Array] + def to_a + if @levels == 0 + # When initializing a Vector with 32 or less items, we always make + # sure @root is frozen, so we can return it directly here + @root + else + flatten_node(@root, @levels * BITS_PER_LEVEL, []) + end + end + alias to_ary to_a + + # Return true if `other` has the same type and contents as this `Vector`. + # + # @param other [Object] The collection to compare with + # @return [Boolean] + def eql?(other) + return true if other.equal?(self) + return false unless instance_of?(other.class) && @size == other.size + @root.eql?(other.instance_variable_get(:@root)) + end + + # See `Object#hash`. + # @return [Integer] + def hash + reduce(0) { |hash, item| (hash << 5) - hash + item.hash } + end + + # Return `self`. Since this is an immutable object duplicates are + # equivalent. + # @return [Vector] + def dup + self + end + alias clone dup + + # @return [::Array] + # @private + def marshal_dump + to_a + end + + # @private + def marshal_load(array) + initialize(array.freeze) + end + + private + + def traverse_depth_first(node, level, &block) + return node.each(&block) if level == 0 + node.each { |child| traverse_depth_first(child, level - 1, &block) } + end + + def reverse_traverse_depth_first(node, level, &block) + return node.reverse_each(&block) if level == 0 + node.reverse_each { |child| reverse_traverse_depth_first(child, level - 1, &block) } + end + + def leaf_node_for(node, bitshift, index) + while bitshift > 0 + node = node[(index >> bitshift) & INDEX_MASK] + bitshift -= BITS_PER_LEVEL + end + node + end + + def update_root(index, item) + root, levels = @root, @levels + while index >= (1 << (BITS_PER_LEVEL * (levels + 1))) + root = [root].freeze + levels += 1 + end + new_root = update_leaf_node(root, levels * BITS_PER_LEVEL, index, item) + if new_root.equal?(root) + self + else + self.class.alloc(new_root, @size > index ? @size : index + 1, levels) + end + end + + def update_leaf_node(node, bitshift, index, item) + slot_index = (index >> bitshift) & INDEX_MASK + if bitshift > 0 + old_child = node[slot_index] || [] + item = update_leaf_node(old_child, bitshift - BITS_PER_LEVEL, index, item) + end + existing_item = node[slot_index] + if existing_item.equal?(item) + node + else + node.dup.tap { |n| n[slot_index] = item }.freeze + end + end + + def flatten_range(node, bitshift, from, to) + from_slot = (from >> bitshift) & INDEX_MASK + to_slot = (to >> bitshift) & INDEX_MASK + + if bitshift == 0 # are we at the bottom? + node.slice(from_slot, to_slot-from_slot+1) + elsif from_slot == to_slot + flatten_range(node[from_slot], bitshift - BITS_PER_LEVEL, from, to) + else + # the following bitmask can be used to pick out the part of the from/to indices + # which will be used to direct path BELOW this node + mask = ((1 << bitshift) - 1) + result = [] + + if from & mask == 0 + flatten_node(node[from_slot], bitshift - BITS_PER_LEVEL, result) + else + result.concat(flatten_range(node[from_slot], bitshift - BITS_PER_LEVEL, from, from | mask)) + end + + (from_slot+1).upto(to_slot-1) do |slot_index| + flatten_node(node[slot_index], bitshift - BITS_PER_LEVEL, result) + end + + if to & mask == mask + flatten_node(node[to_slot], bitshift - BITS_PER_LEVEL, result) + else + result.concat(flatten_range(node[to_slot], bitshift - BITS_PER_LEVEL, to & ~mask, to)) + end + + result + end + end + + def flatten_node(node, bitshift, result) + if bitshift == 0 + result.concat(node) + elsif bitshift == BITS_PER_LEVEL + node.each { |a| result.concat(a) } + else + bitshift -= BITS_PER_LEVEL + node.each { |a| flatten_node(a, bitshift, result) } + end + result + end + + def subsequence(from, length) + return nil if from > @size || from < 0 || length < 0 + length = @size - from if @size < from + length + return self.class.empty if length == 0 + self.class.new(flatten_range(@root, @levels * BITS_PER_LEVEL, from, from + length - 1)) + end + + def flatten_suffix(node, bitshift, from, result) + from_slot = (from >> bitshift) & INDEX_MASK + + if bitshift == 0 + if from_slot == 0 + result.concat(node) + else + result.concat(node.slice(from_slot, 32)) # entire suffix of node. excess length is ignored by #slice + end + else + mask = ((1 << bitshift) - 1) + if from & mask == 0 + from_slot.upto(node.size-1) do |i| + flatten_node(node[i], bitshift - BITS_PER_LEVEL, result) + end + elsif (child = node[from_slot]) + flatten_suffix(child, bitshift - BITS_PER_LEVEL, from, result) + (from_slot+1).upto(node.size-1) do |i| + flatten_node(node[i], bitshift - BITS_PER_LEVEL, result) + end + end + result + end + end + + def replace_suffix(from, suffix) + # new suffix can go directly after existing elements + raise IndexError if from > @size + root, levels = @root, @levels + + if (from >> (BITS_PER_LEVEL * (@levels + 1))) != 0 + # index where new suffix goes doesn't fall within current tree + # we will need to deepen tree + root = [root].freeze + levels += 1 + end + + new_size = from + suffix.size + root = replace_node_suffix(root, levels * BITS_PER_LEVEL, from, suffix) + + if !suffix.empty? + levels.times { suffix = suffix.each_slice(32).to_a } + root.concat(suffix) + while root.size > 32 + root = root.each_slice(32).to_a + levels += 1 + end + else + while root.size == 1 && levels > 0 + root = root[0] + levels -= 1 + end + end + + self.class.alloc(root.freeze, new_size, levels) + end + + def replace_node_suffix(node, bitshift, from, suffix) + from_slot = (from >> bitshift) & INDEX_MASK + + if bitshift == 0 + if from_slot == 0 + suffix.shift(32) + else + node.take(from_slot).concat(suffix.shift(32 - from_slot)) + end + else + mask = ((1 << bitshift) - 1) + if from & mask == 0 + if from_slot == 0 + new_node = suffix.shift(32 * (1 << bitshift)) + while bitshift != 0 + new_node = new_node.each_slice(32).to_a + bitshift -= BITS_PER_LEVEL + end + new_node + else + result = node.take(from_slot) + remainder = suffix.shift((32 - from_slot) * (1 << bitshift)) + while bitshift != 0 + remainder = remainder.each_slice(32).to_a + bitshift -= BITS_PER_LEVEL + end + result.concat(remainder) + end + elsif (child = node[from_slot]) + result = node.take(from_slot) + result.push(replace_node_suffix(child, bitshift - BITS_PER_LEVEL, from, suffix)) + remainder = suffix.shift((31 - from_slot) * (1 << bitshift)) + while bitshift != 0 + remainder = remainder.each_slice(32).to_a + bitshift -= BITS_PER_LEVEL + end + result.concat(remainder) + else + raise "Shouldn't happen" + end + end + end + end + + # The canonical empty `Vector`. Returned by `Vector[]` when + # invoked with no arguments; also returned by `Vector.empty`. Prefer using this + # one rather than creating many empty vectors using `Vector.new`. + # + # @private + EmptyVector = Immutable::Vector.empty + + + # `Immutable::Set` is a collection of unordered values with no duplicates. Testing whether + # an object is present in the `Set` can be done in constant time. `Set` is also `Enumerable`, so you can + # iterate over the members of the set with {#each}, transform them with {#map}, filter + # them with {#select}, and so on. Some of the `Enumerable` methods are overridden to + # return `immutable-ruby` collections. + # + # Like the `Set` class in Ruby's standard library, which we will call RubySet, + # `Immutable::Set` defines equivalency of objects using `#hash` and `#eql?`. No two + # objects with the same `#hash` code, and which are also `#eql?`, can coexist in the + # same `Set`. If one is already in the `Set`, attempts to add another one will have + # no effect. + # + # `Set`s have no natural ordering and cannot be compared using `#<=>`. However, they + # define {#<}, {#>}, {#<=}, and {#>=} as shorthand for {#proper_subset?}, + # {#proper_superset?}, {#subset?}, and {#superset?} respectively. + # + # The basic set-theoretic operations {#union}, {#intersection}, {#difference}, and + # {#exclusion} work with any `Enumerable` object. + # + # A `Set` can be created in either of the following ways: + # + # Immutable::Set.new([1, 2, 3]) # any Enumerable can be used to initialize + # Immutable::Set['A', 'B', 'C', 'D'] + # + # The latter 2 forms of initialization can be used with your own, custom subclasses + # of `Immutable::Set`. + # + # Unlike RubySet, all methods which you might expect to "modify" an `Immutable::Set` + # actually return a new set and leave the existing one unchanged. + # + # @example + # set1 = Immutable::Set[1, 2] # => Immutable::Set[1, 2] + # set2 = Immutable::Set[1, 2] # => Immutable::Set[1, 2] + # set1 == set2 # => true + # set3 = set1.add("foo") # => Immutable::Set[1, 2, "foo"] + # set3 - set2 # => Immutable::Set["foo"] + # set3.subset?(set1) # => false + # set1.subset?(set3) # => true + # + class Set + include Immutable::Enumerable + + class << self + # Create a new `Set` populated with the given items. + # @return [Set] + def [](*items) + items.empty? ? empty : new(items) + end + + # Return an empty `Set`. If used on a subclass, returns an empty instance + # of that class. + # + # @return [Set] + def empty + @empty ||= new + end + + # "Raw" allocation of a new `Set`. Used internally to create a new + # instance quickly after obtaining a modified {Trie}. + # + # @return [Set] + # @private + def alloc(trie = EmptyTrie) + allocate.tap { |s| s.instance_variable_set(:@trie, trie) }.freeze + end + end + + def initialize(items=[]) + @trie = Trie.new(0) + items.each { |item| @trie.put!(item, nil) } + freeze + end + + # Return `true` if this `Set` contains no items. + # @return [Boolean] + def empty? + @trie.empty? + end + + # Return the number of items in this `Set`. + # @return [Integer] + def size + @trie.size + end + alias length size + + # Return a new `Set` with `item` added. If `item` is already in the set, + # return `self`. + # + # @example + # Immutable::Set[1, 2, 3].add(4) # => Immutable::Set[1, 2, 4, 3] + # Immutable::Set[1, 2, 3].add(2) # => Immutable::Set[1, 2, 3] + # + # @param item [Object] The object to add + # @return [Set] + def add(item) + include?(item) ? self : self.class.alloc(@trie.put(item, nil)) + end + alias << add + + # If `item` is not a member of this `Set`, return a new `Set` with `item` added. + # Otherwise, return `false`. + # + # @example + # Immutable::Set[1, 2, 3].add?(4) # => Immutable::Set[1, 2, 4, 3] + # Immutable::Set[1, 2, 3].add?(2) # => false + # + # @param item [Object] The object to add + # @return [Set, false] + def add?(item) + !include?(item) && add(item) + end + + # Return a new `Set` with `item` removed. If `item` is not a member of the set, + # return `self`. + # + # @example + # Immutable::Set[1, 2, 3].delete(1) # => Immutable::Set[2, 3] + # Immutable::Set[1, 2, 3].delete(99) # => Immutable::Set[1, 2, 3] + # + # @param item [Object] The object to remove + # @return [Set] + def delete(item) + trie = @trie.delete(item) + new_trie(trie) + end + + # If `item` is a member of this `Set`, return a new `Set` with `item` removed. + # Otherwise, return `false`. + # + # @example + # Immutable::Set[1, 2, 3].delete?(1) # => Immutable::Set[2, 3] + # Immutable::Set[1, 2, 3].delete?(99) # => false + # + # @param item [Object] The object to remove + # @return [Set, false] + def delete?(item) + include?(item) && delete(item) + end + + # Call the block once for each item in this `Set`. No specific iteration order + # is guaranteed, but the order will be stable for any particular `Set`. If + # no block is given, an `Enumerator` is returned instead. + # + # @example + # Immutable::Set["Dog", "Elephant", "Lion"].each { |e| puts e } + # Elephant + # Dog + # Lion + # # => Immutable::Set["Dog", "Elephant", "Lion"] + # + # @yield [item] Once for each item. + # @return [self, Enumerator] + def each + return to_enum if not block_given? + @trie.each { |key, _| yield(key) } + self + end + + # Call the block once for each item in this `Set`. Iteration order will be + # the opposite of {#each}. If no block is given, an `Enumerator` is + # returned instead. + # + # @example + # Immutable::Set["Dog", "Elephant", "Lion"].reverse_each { |e| puts e } + # Lion + # Dog + # Elephant + # # => Immutable::Set["Dog", "Elephant", "Lion"] + # + # @yield [item] Once for each item. + # @return [self] + def reverse_each + return enum_for(:reverse_each) if not block_given? + @trie.reverse_each { |key, _| yield(key) } + self + end + + # Return a new `Set` with all the items for which the block returns true. + # + # @example + # Immutable::Set["Elephant", "Dog", "Lion"].select { |e| e.size >= 4 } + # # => Immutable::Set["Elephant", "Lion"] + # @yield [item] Once for each item. + # @return [Set] + def select + return enum_for(:select) unless block_given? + trie = @trie.select { |key, _| yield(key) } + new_trie(trie) + end + alias find_all select + alias keep_if select + + # Call the block once for each item in this `Set`. All the values returned + # from the block will be gathered into a new `Set`. If no block is given, + # an `Enumerator` is returned instead. + # + # @example + # Immutable::Set["Cat", "Elephant", "Dog", "Lion"].map { |e| e.size } + # # => Immutable::Set[8, 4, 3] + # + # @yield [item] Once for each item. + # @return [Set] + def map + return enum_for(:map) if not block_given? + return self if empty? + self.class.new(super) + end + alias collect map + + # Return `true` if the given item is present in this `Set`. More precisely, + # return `true` if an object with the same `#hash` code, and which is also `#eql?` + # to the given object is present. + # + # @example + # Immutable::Set["A", "B", "C"].include?("B") # => true + # Immutable::Set["A", "B", "C"].include?("Z") # => false + # + # @param object [Object] The object to check for + # @return [Boolean] + def include?(object) + @trie.key?(object) + end + alias member? include? + + # Return a member of this `Set`. The member chosen will be the first one which + # would be yielded by {#each}. If the set is empty, return `nil`. + # + # @example + # Immutable::Set["A", "B", "C"].first # => "C" + # + # @return [Object] + def first + (entry = @trie.at(0)) && entry[0] + end + + # Return a {SortedSet} which contains the same items as this `Set`, ordered by + # the given comparator block. + # + # @example + # Immutable::Set["Elephant", "Dog", "Lion"].sort + # # => Immutable::SortedSet["Dog", "Elephant", "Lion"] + # Immutable::Set["Elephant", "Dog", "Lion"].sort { |a,b| a.size <=> b.size } + # # => Immutable::SortedSet["Dog", "Lion", "Elephant"] + # + # @yield [a, b] Any number of times with different pairs of elements. + # @yieldreturn [Integer] Negative if the first element should be sorted + # lower, positive if the latter element, or 0 if + # equal. + # @return [SortedSet] + def sort(&comparator) + SortedSet.new(to_a, &comparator) + end + + # Return a {SortedSet} which contains the same items as this `Set`, ordered + # by mapping each item through the provided block to obtain sort keys, and + # then sorting the keys. + # + # @example + # Immutable::Set["Elephant", "Dog", "Lion"].sort_by { |e| e.size } + # # => Immutable::SortedSet["Dog", "Lion", "Elephant"] + # + # @yield [item] Once for each item to create the set, and then potentially + # again depending on what operations are performed on the + # returned {SortedSet}. As such, it is recommended that the + # block be a pure function. + # @yieldreturn [Object] sort key for the item + # @return [SortedSet] + def sort_by(&mapper) + SortedSet.new(to_a, &mapper) + end + + # Return a new `Set` which contains all the members of both this `Set` and `other`. + # `other` can be any `Enumerable` object. + # + # @example + # Immutable::Set[1, 2] | Immutable::Set[2, 3] # => Immutable::Set[1, 2, 3] + # + # @param other [Enumerable] The collection to merge with + # @return [Set] + def union(other) + if other.is_a?(Immutable::Set) + if other.size > size + small_set_pairs = @trie + large_set_trie = other.instance_variable_get(:@trie) + else + small_set_pairs = other.instance_variable_get(:@trie) + large_set_trie = @trie + end + else + if other.respond_to?(:lazy) + small_set_pairs = other.lazy.map { |e| [e, nil] } + else + small_set_pairs = other.map { |e| [e, nil] } + end + large_set_trie = @trie + end + + trie = large_set_trie.bulk_put(small_set_pairs) + new_trie(trie) + end + alias | union + alias + union + alias merge union + + # Return a new `Set` which contains all the items which are members of both + # this `Set` and `other`. `other` can be any `Enumerable` object. + # + # @example + # Immutable::Set[1, 2] & Immutable::Set[2, 3] # => Immutable::Set[2] + # + # @param other [Enumerable] The collection to intersect with + # @return [Set] + def intersection(other) + if other.size < @trie.size + if other.is_a?(Immutable::Set) + trie = other.instance_variable_get(:@trie).select { |key, _| include?(key) } + else + trie = Trie.new(0) + other.each { |obj| trie.put!(obj, nil) if include?(obj) } + end + else + trie = @trie.select { |key, _| other.include?(key) } + end + new_trie(trie) + end + alias & intersection + + # Return a new `Set` with all the items in `other` removed. `other` can be + # any `Enumerable` object. + # + # @example + # Immutable::Set[1, 2] - Immutable::Set[2, 3] # => Immutable::Set[1] + # + # @param other [Enumerable] The collection to subtract from this set + # @return [Set] + def difference(other) + trie = if (@trie.size <= other.size) && (other.is_a?(Immutable::Set) || (defined?(::Set) && other.is_a?(::Set))) + @trie.select { |key, _| !other.include?(key) } + else + @trie.bulk_delete(other) + end + new_trie(trie) + end + alias subtract difference + alias - difference + + # Return a new `Set` which contains all the items which are members of this + # `Set` or of `other`, but not both. `other` can be any `Enumerable` object. + # + # @example + # Immutable::Set[1, 2] ^ Immutable::Set[2, 3] # => Immutable::Set[1, 3] + # + # @param other [Enumerable] The collection to take the exclusive disjunction of + # @return [Set] + def exclusion(other) + ((self | other) - (self & other)) + end + alias ^ exclusion + + # Return `true` if all items in this `Set` are also in `other`. + # + # @example + # Immutable::Set[2, 3].subset?(Immutable::Set[1, 2, 3]) # => true + # + # @param other [Set] + # @return [Boolean] + def subset?(other) + return false if other.size < size + + # This method has the potential to be very slow if 'other' is a large Array, so to avoid that, + # we convert those Arrays to Sets before checking presence of items + # Time to convert Array -> Set is linear in array.size + # Time to check for presence of all items in an Array is proportional to set.size * array.size + # Note that both sides of that equation have array.size -- hence those terms cancel out, + # and the break-even point is solely dependent on the size of this collection + # After doing some benchmarking to estimate the constants, it appears break-even is at ~190 items + # We also check other.size, to avoid the more expensive #is_a? checks in cases where it doesn't matter + # + if other.size >= 150 && @trie.size >= 190 && !(other.is_a?(Immutable::Set) || other.is_a?(::Set)) + other = ::Set.new(other) + end + all? { |item| other.include?(item) } + end + alias <= subset? + + # Return `true` if all items in `other` are also in this `Set`. + # + # @example + # Immutable::Set[1, 2, 3].superset?(Immutable::Set[2, 3]) # => true + # + # @param other [Set] + # @return [Boolean] + def superset?(other) + other.subset?(self) + end + alias >= superset? + + # Returns `true` if `other` contains all the items in this `Set`, plus at least + # one item which is not in this set. + # + # @example + # Immutable::Set[2, 3].proper_subset?(Immutable::Set[1, 2, 3]) # => true + # Immutable::Set[1, 2, 3].proper_subset?(Immutable::Set[1, 2, 3]) # => false + # + # @param other [Set] + # @return [Boolean] + def proper_subset?(other) + return false if other.size <= size + # See comments above + if other.size >= 150 && @trie.size >= 190 && !(other.is_a?(Immutable::Set) || other.is_a?(::Set)) + other = ::Set.new(other) + end + all? { |item| other.include?(item) } + end + alias < proper_subset? + + # Returns `true` if this `Set` contains all the items in `other`, plus at least + # one item which is not in `other`. + # + # @example + # Immutable::Set[1, 2, 3].proper_superset?(Immutable::Set[2, 3]) # => true + # Immutable::Set[1, 2, 3].proper_superset?(Immutable::Set[1, 2, 3]) # => false + # + # @param other [Set] + # @return [Boolean] + def proper_superset?(other) + other.proper_subset?(self) + end + alias > proper_superset? + + # Return `true` if this `Set` and `other` do not share any items. + # + # @example + # Immutable::Set[1, 2].disjoint?(Immutable::Set[8, 9]) # => true + # + # @param other [Set] + # @return [Boolean] + def disjoint?(other) + if other.size <= size + other.each { |item| return false if include?(item) } + else + # See comment on #subset? + if other.size >= 150 && @trie.size >= 190 && !(other.is_a?(Immutable::Set) || other.is_a?(::Set)) + other = ::Set.new(other) + end + each { |item| return false if other.include?(item) } + end + true + end + + # Return `true` if this `Set` and `other` have at least one item in common. + # + # @example + # Immutable::Set[1, 2].intersect?(Immutable::Set[2, 3]) # => true + # + # @param other [Set] + # @return [Boolean] + def intersect?(other) + !disjoint?(other) + end + + # Recursively insert the contents of any nested `Set`s into this `Set`, and + # remove them. + # + # @example + # Immutable::Set[Immutable::Set[1, 2], Immutable::Set[3, 4]].flatten + # # => Immutable::Set[1, 2, 3, 4] + # + # @return [Set] + def flatten + reduce(self.class.empty) do |set, item| + next set.union(item.flatten) if item.is_a?(Set) + set.add(item) + end + end + + alias group group_by + alias classify group_by + + # Return a randomly chosen item from this `Set`. If the set is empty, return `nil`. + # + # @example + # Immutable::Set[1, 2, 3, 4, 5].sample # => 3 + # + # @return [Object] + def sample + empty? ? nil : @trie.at(rand(size))[0] + end + + # Return an empty `Set` instance, of the same class as this one. Useful if you + # have multiple subclasses of `Set` and want to treat them polymorphically. + # + # @return [Set] + def clear + self.class.empty + end + + # Return true if `other` has the same type and contents as this `Set`. + # + # @param other [Object] The object to compare with + # @return [Boolean] + def eql?(other) + return true if other.equal?(self) + return false if not instance_of?(other.class) + other_trie = other.instance_variable_get(:@trie) + return false if @trie.size != other_trie.size + @trie.each do |key, _| + return false if !other_trie.key?(key) + end + true + end + alias == eql? + + # See `Object#hash`. + # @return [Integer] + def hash + reduce(0) { |hash, item| (hash << 5) - hash + item.hash } + end + + # Return `self`. Since this is an immutable object duplicates are + # equivalent. + # @return [Set] + def dup + self + end + alias clone dup + + undef :"<=>" # Sets are not ordered, so Enumerable#<=> will give a meaningless result + undef :each_index # Set members cannot be accessed by 'index', so #each_index is not meaningful + + # Return `self`. + # + # @return [self] + def to_set + self + end + + # @private + def marshal_dump + output = {} + each do |key| + output[key] = nil + end + output + end + + # @private + def marshal_load(dictionary) + @trie = dictionary.reduce(EmptyTrie) do |trie, key_value| + trie.put(key_value.first, nil) + end + end + + private + + def new_trie(trie) + if trie.empty? + self.class.empty + elsif trie.equal?(@trie) + self + else + self.class.alloc(trie) + end + end + end + + # The canonical empty `Set`. Returned by `Set[]` when + # invoked with no arguments; also returned by `Set.empty`. Prefer using this + # one rather than creating many empty sets using `Set.new`. + # + # @private + EmptySet = Immutable::Set.empty +end |