dice.rb in games_dice-0.4.0

- old
+ new
@@ -1,143 +1,146 @@
-# This class models a combination of GamesDice::Bunch objects plus a fixed offset.
-#
-# An object of this class is a dice "recipe" that specifies the numbers and types of
-# dice that can be rolled to generate an integer value.
-#
-# @example '3d6+6' hitpoints, whatever that means in the game you are playing
-#  d = GamesDice::Dice.new( [{:ndice => 3, :sides => 6}], 6, 'Hit points' )
-#  d.roll # => 20
-#  d.result # => 20
-#  d.explain_result # => "3d6: 3 + 5 + 6 = 14. 14 + 6 = 20"
-#  d.probabilities.expected # => 16.5
-#
-# @example Roll d20 twice, take best result, and add 5.
-#  d = GamesDice::Dice.new( [{:ndice => 2, :sides => 20 , :keep_mode => :keep_best, :keep_number => 1}], 5 )
-#  d.roll # => 21
-#  d.result # => 21
-#  d.explain_result # => "2d20: 4, 16. Keep: 16. 16 + 5 = 21"
-#
-class GamesDice::Dice
-  # The first parameter is an array of values that are passed to GamesDice::Bunch constructors.
-  # @param [Array<Hash>] bunches Array of options for creating bunches
-  # @param [Integer] offset Total offset
-  # @param [String] name Optional label for the dice
-  # @option bunches [Integer] :ndice Number of dice in the bunch, *mandatory*
-  # @option bunches [Integer] :sides Number of sides on a single die in the bunch, *mandatory*
-  # @option bunches [String] :name Optional name for the bunch
-  # @option bunches [Array<GamesDice::RerollRule,Array>] :rerolls Optional rules that cause the die to roll again
-  # @option bunches [Array<GamesDice::MapRule,Array>] :maps Optional rules to convert a value into a final result for the die
-  # @option bunches [#rand] :prng Optional alternative source of randomness to Ruby's built-in #rand, passed to GamesDice::Die's constructor
-  # @option bunches [Symbol] :keep_mode Optional, either *:keep_best* or *:keep_worst*
-  # @option bunches [Integer] :keep_number Optional number of dice to keep when :keep_mode is not nil
-  # @option bunches [Integer] :multiplier Optional, defaults to 1, and typically 1 or -1 to describe whether the Bunch total is to be added or subtracted
-  # @return [GamesDice::Dice]
-  def initialize( bunches, offset = 0, name = '' )
-    @name = name
-    @offset = offset
-    @bunches = bunches.map { |b| GamesDice::Bunch.new( b ) }
-    @bunch_multipliers = bunches.map { |b| b[:multiplier] || 1 }
-    @result = nil
-  end
-
-  # Name to help identify dice
-  # @return [String]
-  attr_reader :name
-
-  # Bunches of dice that are components of the object
-  # @return [Array<GamesDice::Bunch>]
-  attr_reader :bunches
-
-  # Multipliers for each bunch of identical dice. Typically 1 or -1 to represent groups of dice that
-  # are either added or subtracted from the total.
-  # @return [Array<Integer>]
-  attr_reader :bunch_multipliers
-
-  # Fixed offset added to sum of all bunches.
-  # @return [Integer]
-  attr_reader :offset
-
-  # Result of most-recent roll, or nil if no roll made yet.
-  # @return [Integer,nil]
-  attr_reader :result
-
-  # Simulates rolling dice
-  # @return [Integer] Sum of all rolled dice
-  def roll
-    @result = @offset + bunches_weighted_sum( :roll )
-  end
-
-  # @!attribute [r] min
-  # Minimum possible result from a call to #roll
-  # @return [Integer]
-  def min
-    @min ||= @offset + bunches_weighted_sum( :min )
-  end
-
-  # @!attribute [r] max
-  # Maximum possible result from a call to #roll
-  # @return [Integer]
-  def max
-    @max ||= @offset + bunches_weighted_sum( :max )
-  end
-
-  # @!attribute [r] minmax
-  # Convenience method, same as [dice.min, dice.max]
-  # @return [Array<Integer>]
-  def minmax
-    [min,max]
-  end
-
-  # Calculates the probability distribution for the dice. When the dice include components with
-  # open-ended re-roll rules, there are some arbitrary limits imposed to prevent large amounts of
-  # recursion.
-  # @return [GamesDice::Probabilities] Probability distribution of dice.
-  def probabilities
-    return @probabilities if @probabilities
-    probs = @bunch_multipliers.zip(@bunches).inject( GamesDice::Probabilities.new( [1.0], @offset ) ) do |probs, mb|
-      m,b = mb
-      GamesDice::Probabilities.add_distributions_mult( 1, probs, m, b.probabilities )
-    end
-  end
-
-  # @!attribute [r] explain_result
-  # @return [String,nil] Explanation of result, or nil if no call to #roll yet.
-  def explain_result
-    return nil unless @result
-    explanations = @bunches.map { |bunch| bunch.label + ": " + bunch.explain_result }
-
-    if explanations.count == 0
-      return @offset.to_s
-    end
-
-    if explanations.count == 1
-      if @offset !=0
-        return explanations[0] + '. ' + array_to_sum( [ @bunches[0].result, @offset ] )
-      else
-        return explanations[0]
-      end
-    end
-
-    bunch_values = @bunch_multipliers.zip(@bunches).map { |m,b| m * b.result }
-    bunch_values << @offset if @offset != 0
-    explanations << array_to_sum( bunch_values )
-    return explanations.join('. ')
-  end
-
-  private
-
-  def array_to_sum array
-    ( numbers_to_strings(array) + [ '=', array.inject(:+) ] ).join(' ')
-  end
-
-  def numbers_to_strings array
-    [ array.first.to_s ] + array.drop(1).map { |n| n < 0 ? '- ' + n.abs.to_s : '+ ' + n.to_s }
-  end
-
-  def bunches_weighted_sum summed_method
-    @bunch_multipliers.zip(@bunches).inject(0) do |total,mb|
-      m,b = mb
-      total += m * b.send( summed_method )
-    end
-  end
-
-end # class Dice
+# frozen_string_literal: true
+
+module GamesDice
+  # This class models a combination of GamesDice::Bunch objects plus a fixed offset.
+  #
+  # An object of this class is a dice "recipe" that specifies the numbers and types of
+  # dice that can be rolled to generate an integer value.
+  #
+  # @example '3d6+6' hitpoints, whatever that means in the game you are playing
+  #  d = GamesDice::Dice.new( [{:ndice => 3, :sides => 6}], 6, 'Hit points' )
+  #  d.roll # => 20
+  #  d.result # => 20
+  #  d.explain_result # => "3d6: 3 + 5 + 6 = 14. 14 + 6 = 20"
+  #  d.probabilities.expected # => 16.5
+  #
+  # @example Roll d20 twice, take best result, and add 5.
+  #  d = GamesDice::Dice.new( [{:ndice => 2, :sides => 20 , :keep_mode => :keep_best, :keep_number => 1}], 5 )
+  #  d.roll # => 21
+  #  d.result # => 21
+  #  d.explain_result # => "2d20: 4, 16. Keep: 16. 16 + 5 = 21"
+  #
+  class Dice
+    # The first parameter is an array of values that are passed to GamesDice::Bunch constructors.
+    # @param [Array<Hash>] bunches Array of options for creating bunches
+    # @param [Integer] offset Total offset
+    # @param [String] name Optional label for the dice
+    # @option bunches [Integer] :ndice Number of dice in the bunch, *mandatory*
+    # @option bunches [Integer] :sides Number of sides on a single die in the bunch, *mandatory*
+    # @option bunches [String] :name Optional name for the bunch
+    # @option bunches [Array<GamesDice::RerollRule,Array>] :rerolls Optional rules that cause the die to roll again
+    # @option bunches [Array<GamesDice::MapRule,Array>] :maps Optional rules to convert a value into a final result for the die
+    # @option bunches [#rand] :prng Optional alternative source of randomness to Ruby's built-in #rand, passed to GamesDice::Die's constructor
+    # @option bunches [Symbol] :keep_mode Optional, either *:keep_best* or *:keep_worst*
+    # @option bunches [Integer] :keep_number Optional number of dice to keep when :keep_mode is not nil
+    # @option bunches [Integer] :multiplier Optional, defaults to 1, and typically 1 or -1 to describe whether the Bunch total is to be added or subtracted
+    # @return [GamesDice::Dice]
+    def initialize(bunches, offset = 0, name = '')
+      @name = name
+      @offset = offset
+      @bunches = bunches.map { |b| GamesDice::Bunch.new(b) }
+      @bunch_multipliers = bunches.map { |b| b[:multiplier] || 1 }
+      @result = nil
+    end
+
+    # Name to help identify dice
+    # @return [String]
+    attr_reader :name
+
+    # Bunches of dice that are components of the object
+    # @return [Array<GamesDice::Bunch>]
+    attr_reader :bunches
+
+    # Multipliers for each bunch of identical dice. Typically 1 or -1 to represent groups of dice that
+    # are either added or subtracted from the total.
+    # @return [Array<Integer>]
+    attr_reader :bunch_multipliers
+
+    # Fixed offset added to sum of all bunches.
+    # @return [Integer]
+    attr_reader :offset
+
+    # Result of most-recent roll, or nil if no roll made yet.
+    # @return [Integer,nil]
+    attr_reader :result
+
+    # Simulates rolling dice
+    # @return [Integer] Sum of all rolled dice
+    def roll
+      @result = @offset + bunches_weighted_sum(:roll)
+    end
+
+    # @!attribute [r] min
+    # Minimum possible result from a call to #roll
+    # @return [Integer]
+    def min
+      @min ||= @offset + bunches_weighted_sum(:min)
+    end
+
+    # @!attribute [r] max
+    # Maximum possible result from a call to #roll
+    # @return [Integer]
+    def max
+      @max ||= @offset + bunches_weighted_sum(:max)
+    end
+
+    # @!attribute [r] minmax
+    # Convenience method, same as [dice.min, dice.max]
+    # @return [Array<Integer>]
+    def minmax
+      [min, max]
+    end
+
+    # Calculates the probability distribution for the dice. When the dice include components with
+    # open-ended re-roll rules, there are some arbitrary limits imposed to prevent large amounts of
+    # recursion.
+    # @return [GamesDice::Probabilities] Probability distribution of dice.
+    def probabilities
+      return @probabilities if @probabilities
+
+      @bunch_multipliers.zip(@bunches).inject(GamesDice::Probabilities.new([1.0], @offset)) do |probs, mb|
+        m, b = mb
+        GamesDice::Probabilities.add_distributions_mult(1, probs, m, b.probabilities)
+      end
+    end
+
+    # @!attribute [r] explain_result
+    # @return [String,nil] Explanation of result, or nil if no call to #roll yet.
+    def explain_result
+      return nil unless @result
+
+      explanations = @bunches.map { |bunch| "#{bunch.label}: #{bunch.explain_result}" }
+
+      return @offset.to_s if explanations.count.zero?
+
+      return simple_explanation(explanations.first) if explanations.count == 1
+
+      bunch_values = @bunch_multipliers.zip(@bunches).map { |m, b| m * b.result }
+      bunch_values << @offset if @offset != 0
+      explanations << array_to_sum(bunch_values)
+      explanations.join('. ')
+    end
+
+    private
+
+    def simple_explanation(explanation)
+      return explanation if @offset.zero?
+
+      "#{explanation}. #{array_to_sum([@bunches[0].result, @offset])}"
+    end
+
+    def array_to_sum(array)
+      (numbers_to_strings(array) + ['=', array.inject(:+)]).join(' ')
+    end
+
+    def numbers_to_strings(array)
+      [array.first.to_s] + array.drop(1).map { |n| n.negative? ? "- #{n.abs}" : "+ #{n}" }
+    end
+
+    def bunches_weighted_sum(summed_method)
+      @bunch_multipliers.zip(@bunches).inject(0) do |total, mb|
+        m, b = mb
+        total + (m * b.send(summed_method))
+      end
+    end
+  end
+end