Module: Enumerable

Defined in:
lib/mug/top.rb,
lib/mug/bool.rb,
lib/mug/enumerable/chain.rb,
lib/mug/enumerable/counts.rb,
lib/mug/enumerable/hash-like.rb,
lib/mug/enumerable/any-and-all.rb

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.chain(*enums) ⇒ Enumerator, void

Note:

The instance method Enumerable#chain is provided as a polyfill for Ruby < 2.6. On Ruby 2.6+, the built-in Enumerable#chain (which returns a lazy Enumerator::Chain) is used instead.

Invokes a block once for every element in a sequence of Enumerables.

Examples:

require 'mug/enumerable/chain'
Enumerable.chain([1, 2], [3, 4]) {|x| puts x }
# prints 1, 2, 3, 4

Parameters:

Returns:

  • (Enumerator) —

    if no block is given

  • (void) —

    if a block is given



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# File 'lib/mug/enumerable/chain.rb', line 23

def chain *enums
  return enum_for(:chain, *enums) unless block_given?
  enums.each do |enum|
    enum.each {|*args| yield(*args) }
  end
end

Instance Method Details

#any_and_all?(&block) ⇒ Boolean

Passes each element of the collection to the given block. The method returns true if the block contains elements that never return false or nil. If the block is not given, Ruby adds an implicit block of { |obj| obj } which will cause any_and_all? to return true when none of the collection members are false or nil.

Examples:

require 'mug/enumerable/any-and-all'
[1, 2, 3].any_and_all?        #=> true
[1, nil, 3].any_and_all?      #=> false
[].any_and_all?               #=> false
[2, 4, 6].any_and_all?(&:even?)  #=> true

Returns:

  • (Boolean) —

    true if the collection is non-empty and all elements are truthy



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# File 'lib/mug/enumerable/any-and-all.rb', line 19

def any_and_all? &block
  block ||= proc {|obj| obj }

  result = false
  each do |x|
    return false unless block[x]
    result = true
  end
  result
end

#bottom(n = 1) {|a, b| ... } ⇒ Array

Note:

bottom(n) is similar to Enumerable#min(n) (Ruby 2.2+).

Get the bottom n items, ordered from bottom to top.

Returns an Array even when n is 1.

Parameters:

  • n (Integer) (defaults to: 1) —

    the number of items to return

Yields:

  • (a, b) —

    optional comparison block

Yield Parameters:

  • a (Object) —

    an element to compare

  • b (Object) —

    an element to compare

Returns:

  • (Array) —

    the bottom n items

See Also:

  • #sort


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# File 'lib/mug/top.rb', line 83

def bottom n=1, &blk
  if block_given?
    sort(&blk)[0...n]
  else
    #bottom_by(n) {|x| x }
    sort[0...n]
  end
end

#bottom_by(n = 1) {|item| ... } ⇒ Array, Enumerator

Note:

Similar to Enumerable#min_by(n) (Ruby 2.2+), but guarantees stable ordering among tied elements.

Get the bottom n items, in order from bottom to top, ordered by mapping the values through the given block.

Returns an Array even when n is 1. Values that are tied after mapping are returned in the initial order.

If no block is given, an enumerator is returned instead.

Parameters:

  • n (Integer) (defaults to: 1) —

    the number of items to return

Yields:

  • (item) —

    mapping block

Yield Parameters:

  • item (Object) —

    an element to map

Returns:

See Also:

  • #sort_by


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# File 'lib/mug/top.rb', line 112

def bottom_by n=1, &_blk
  return enum_for(:bottom_by, n) unless block_given?
  chain = {}
  each do |x|
    y = yield x
    chain[y] ||= []
    chain[y] << x
  end
  ary = []
  chain.keys.sort.each do |k|
    ary += chain[k]
    break if ary.length > n
  end
  ary[0...n]
end

#counts(&block) ⇒ Hash

Note:

Similar to Enumerable#tally (Ruby 2.7+). Unlike tally, the returned hash has a default value of 0 for missing keys.

Returns a hash of item=>count showing how many of each item are in this Enumerable.

Examples:

require 'mug/enumerable/counts'
%w(a b b).counts  #=> {'a'=>1, 'b'=>2}

Returns:

  • (Hash) —

    a hash mapping each item to its count, with a default value of 0



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# File 'lib/mug/enumerable/counts.rb', line 17

def counts &block
  return counts_by(&block) if block_given?
  hsh = Hash.new{|h,k| h[k] = 0 }
  each do |k|
    hsh[k] += 1
  end
  hsh
end

#counts_by(&_block) ⇒ Hash, Enumerator

Note:

Similar to Enumerable#tally (Ruby 2.7+). Unlike tally, the returned hash has a default value of 0 for missing keys.

Passes each element in turn to the block, and returns a hash of result=>count.

If no block is given, an enumerator is returned.

Examples:

require 'mug/enumerable/counts'
%w(a b b).counts_by {|o| o.upcase }  #=> {'A'=>1, 'B'=>2}

Returns:

  • (Hash) —

    a hash mapping each block result to its count, with a default value of 0

  • (Enumerator) —

    if no block is given



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# File 'lib/mug/enumerable/counts.rb', line 42

def counts_by &_block
  return enum_for(:counts_by) unless block_given?
  hsh = Hash.new{|h,k| h[k] = 0 }
  each do |j|
    k = yield j
    hsh[k] += 1
  end
  hsh
end

#each_key ⇒ Object

Calls block once for each key in the enum, passing the key as a parameter. If no block is given, an enumerator is returned instead.

@call-seq each_key {| key | block } -> hsh @call-seq each_key -> an_enumerator



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# File 'lib/mug/enumerable/hash-like.rb', line 23

def each_key
  return enum_for(:each_key) unless block_given?

  # FIXME
  each_with_index {|_,i| yield i }
end

#each_pair ⇒ Object

Calls block once for each key in the enum, passing the key-value pair as parameters. If no block is given, an enumerator is returned instead.

@call-seq each_pair {| key, value | block } -> hsh @call-seq each_pair -> an_enumerator



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# File 'lib/mug/enumerable/hash-like.rb', line 11

def each_pair
  return enum_for(:each_pair) unless block_given?
  each_with_index {|e,i| yield i, e }
end

#fetch(*args) ⇒ Object

Returns a value from the enum for the given key. If the key can't be found, there are several options: With no other arguments, it will raise a KeyError exception; if default is given, then that will be returned; if the optional code block is specified, then that will be run and its result returned.

@call-seq fetch(key [, default] ) -> obj @call-seq fetch(key) { |key| block } -> obj

Raises:

  • (ArgumentError) 


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# File 'lib/mug/enumerable/hash-like.rb', line 42

def fetch *args
  raise ArgumentError, "incorrect number of arguments (#{args.length} for 1..2)" if args.length < 1 || args.length > 2
  key, default = *args

  each_pair do |k,v|
    return v if k == key
  end
  if args.length > 1
    default
  elsif block_given?
    yield key
  else
    raise KeyError, 'key not found'
  end
end

#fetch_values(*keys) ⇒ Object

Returns an array containing the values associated with the given keys but also raises KeyError when one of keys can't be found. Also see #values_at and #fetch.

@call-seq fetch_values(key, ...) -> array @call-seq fetch_values(key, ...) { |key| block } -> array



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# File 'lib/mug/enumerable/hash-like.rb', line 66

def fetch_values *keys
  key_map = {}
  keys.each_with_index do |key, index|
    key_map[key] ||= []
    key_map[key] << index
  end

  remain = keys.length
  result = [nil] * keys.length
  define = [nil] * keys.length

  each_pair do |k,v|
    break if remain < 1

    key_indices = key_map[k]
    next unless key_indices

    key_indices.each do |key_index|
      result[key_index] = v
      define[key_index] = true
      remain -= 1
    end
  end

  if remain > 0
    if block_given?
      define.each_with_index do |isdef, index|
        next if isdef
        result[index] = yield keys[index]
      end
    else
      index = define.index nil
      raise KeyError, "key not found: #{keys[index].inspect}"
    end
  end

  result
end

#key?(key) ⇒ Boolean Also known as: has_key?

Returns true if the given key is present in this enum.

@call-seq key?(key) -> true or false

Returns:

  • (Boolean) 


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# File 'lib/mug/enumerable/hash-like.rb', line 112

def key? key
  each_pair.find {|k, _| key == k } && true
end

#keys ⇒ Object

Returns a new array populated with the keys from this enum.

@call-seq keys -> array



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# File 'lib/mug/enumerable/hash-like.rb', line 122

def keys
  each_with_index.map {|_, index| index }
end

#length ⇒ Object Also known as: size

Returns the number of key-value pairs in the hash.

@call-seq length -> integer



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# File 'lib/mug/enumerable/hash-like.rb', line 131

def length
  reduce(0) {|sum,_| sum + 1 }
end

#member?(key) ⇒ Boolean

Returns true if the given key is present in this enum.

@call-seq member?(key) -> true or false

Returns:

  • (Boolean) 


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# File 'lib/mug/enumerable/hash-like.rb', line 142

def member? key
  fetch(key, nil) && true
end

#slice(*keys) ⇒ Object

Returns a hash containing only the given keys and their values.

@call-seq slice(*keys) -> a_hash



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# File 'lib/mug/enumerable/hash-like.rb', line 151

def slice *keys
  missing = {}
  values = fetch_values(*keys) {|key| missing[key] = nil }

  result = {}
  values.each_with_index do |val, i|
    key = keys[i]
    next if missing.key? key
    next if result.key? key
    result[key] = val
  end
  result
end

#to_b ⇒ Boolean

Converts enum to a boolean. Returns true if there are any elements.

Returns:

  • (Boolean) —

    true if self contains any elements



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# File 'lib/mug/bool.rb', line 136

def to_b
  any?{ true }
end

#top(n = 1) {|a, b| ... } ⇒ Array

Note:

top(n) is similar to Enumerable#max(n) (Ruby 2.2+).

Get the top n items, in order from top to bottom.

Returns an Array even when n is 1.

Parameters:

  • n (Integer) (defaults to: 1) —

    the number of items to return

Yields:

  • (a, b) —

    optional comparison block

Yield Parameters:

  • a (Object) —

    an element to compare

  • b (Object) —

    an element to compare

Returns:

  • (Array) —

    the top n items

See Also:

  • #sort


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# File 'lib/mug/top.rb', line 19

def top n=1, &_blk
  if block_given?
    sort{|x,y| yield y, x }[0...n]
  else
    #top_by(n) {|x| x }
    if n <= length
      sort[-n..-1].reverse
    else
      sort.reverse
    end
  end
end

#top_by(n = 1) {|item| ... } ⇒ Array, Enumerator

Note:

Similar to Enumerable#max_by(n) (Ruby 2.2+), but guarantees stable ordering among tied elements.

Get the top n items, in order from top to bottom, ordered by mapping the values through the given block.

Returns an Array even when n is 1. Values that are tied after mapping are returned in the initial order.

If no block is given, an enumerator is returned instead.

Parameters:

  • n (Integer) (defaults to: 1) —

    the number of items to return

Yields:

  • (item) —

    mapping block

Yield Parameters:

  • item (Object) —

    an element to map

Returns:

See Also:

  • #sort_by


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# File 'lib/mug/top.rb', line 52

def top_by n=1, &_blk
  return enum_for(:top_by, n) unless block_given?
  chain = {}
  each do |x|
    y = yield x
    chain[y] ||= []
    chain[y] << x
  end
  ary = []
  chain.keys.sort.reverse.each do |k|
    ary += chain[k]
    break if ary.length > n
  end
  ary[0...n]
end

#transform_keys ⇒ Object

Returns a new hash with the results of running the block once for every key. If no block is given, an enumerator is returned instead.

@call-seq transform_keys {|key| block } -> new_hash @call-seq transform_keys -> an_enumerator



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# File 'lib/mug/enumerable/hash-like.rb', line 172

def transform_keys
  return enum_for(:transform_keys) unless block_given?
  result = {}
  each_pair do |key, value|
    newkey = yield key
    result[newkey] = value
  end
  result
end

#transform_values ⇒ Object

Returns a new hash with the results of running the block once for every value. If no block is given, an enumerator is returned instead.

@call-seq transform_values {|value| block } -> new_hash @call-seq transform_values -> an_enumerator



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# File 'lib/mug/enumerable/hash-like.rb', line 189

def transform_values
  return enum_for(:transform_values) unless block_given?
  result = {}
  each_pair do |key, value|
    newvalue = yield value
    result[key] = newvalue
  end
  result
end

#value?(value) ⇒ Boolean Also known as: has_value?

Returns true if the given value is present for some key.

@call-seq value?(value) -> true or false

Returns:

  • (Boolean) 


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# File 'lib/mug/enumerable/hash-like.rb', line 204

def value? value
  include? value
end

#values ⇒ Object

Returns a new array populated with the values from this enum.

@call-seq values -> array



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# File 'lib/mug/enumerable/hash-like.rb', line 214

def values
  to_a
end

#values_at(*keys) ⇒ Object

Return an array containing the values associated with the given keys.

@call-seq values_at(key, ...) -> array



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# File 'lib/mug/enumerable/hash-like.rb', line 223

def values_at *keys
  fetch_values(*keys) {|key| nil }
end