From d9fee4517626c8d747b5e8aa7858f9ed77f9685e Mon Sep 17 00:00:00 2001
From: Adrian Mugnolo <adrian@mugnolo.com>
Date: Tue, 15 Jul 2008 01:17:03 -0300
Subject: [PATCH] Add in_groups to ActiveSupport::CoreExtensions::Array::Grouping

---
 .../lib/active_support/core_ext/array/grouping.rb  |   47 ++++++++++++++++++-
 activesupport/test/core_ext/array_ext_test.rb      |   50 ++++++++++++++++++--
 2 files changed, 91 insertions(+), 6 deletions(-)

diff --git a/activesupport/lib/active_support/core_ext/array/grouping.rb b/activesupport/lib/active_support/core_ext/array/grouping.rb
index 767acc4..a57619a 100644
--- a/activesupport/lib/active_support/core_ext/array/grouping.rb
+++ b/activesupport/lib/active_support/core_ext/array/grouping.rb
@@ -4,8 +4,8 @@ module ActiveSupport #:nodoc:
   module CoreExtensions #:nodoc:
     module Array #:nodoc:
       module Grouping
-        # Iterates over the array in groups of size +number+, padding any remaining 
-        # slots with +fill_with+ unless it is +false+.
+        # Splits or iterates over the array in groups of size +number+,
+        # padding any remaining slots with +fill_with+ unless it is +false+.
         # 
         #   %w(1 2 3 4 5 6 7).in_groups_of(3) {|g| p g}
         #   ["1", "2", "3"]
@@ -39,6 +39,49 @@ module ActiveSupport #:nodoc:
           end
         end
 
+        # Splits or iterates over the array in +number+ of groups, padding any
+        # remaining slots with +fill_with+ unless it is +false+.
+        #
+        #   %w(1 2 3 4 5 6 7 8 9 10).in_groups(3) {|g| p g}
+        #   ["1", "2", "3", "4"]
+        #   ["5", "6", "7", nil]
+        #   ["8", "9", "10", nil]
+        #
+        #   %w(1 2 3 4 5 6 7).in_groups(3, '&nbsp;') {|g| p g}
+        #   ["1", "2", "3"]
+        #   ["4", "5", "&nbsp;"]
+        #   ["6", "7", "&nbsp;"]
+        #
+        #   %w(1 2 3 4 5 6 7).in_groups(3, false) {|g| p g}
+        #   ["1", "2", "3"]
+        #   ["4", "5"]
+        #   ["6", "7"]
+        def in_groups(number, fill_with = nil, &block)
+          # size / number gives minor group size;
+          # size % number gives how many objects need extra accomodation;
+          # each group hold either division or division + 1 items.
+          division = size / number
+          modulo = size % number
+
+          # create a new array avoiding dup
+          groups = []
+          start = 0
+
+          number.times do |index|
+            length = division + (modulo > 0 && modulo > index ? 1 : 0)
+            padding = fill_with != false &&
+              modulo > 0 && length == division ? 1 : 0
+            groups << slice(start, length).concat([fill_with] * padding)
+            start += length
+          end
+
+          if block_given?
+            groups.each(&block)
+          else
+            groups
+          end
+        end
+
         # Divides the array into one or more subarrays based on a delimiting +value+
         # or the result of an optional block.
         #
diff --git a/activesupport/test/core_ext/array_ext_test.rb b/activesupport/test/core_ext/array_ext_test.rb
index 7563be4..62a1f61 100644
--- a/activesupport/test/core_ext/array_ext_test.rb
+++ b/activesupport/test/core_ext/array_ext_test.rb
@@ -99,7 +99,7 @@ class ArrayExtToSTests < Test::Unit::TestCase
 end
 
 class ArrayExtGroupingTests < Test::Unit::TestCase
-  def test_group_by_with_perfect_fit
+  def test_in_groups_of_with_perfect_fit
     groups = []
     ('a'..'i').to_a.in_groups_of(3) do |group|
       groups << group
@@ -109,7 +109,7 @@ class ArrayExtGroupingTests < Test::Unit::TestCase
     assert_equal [%w(a b c), %w(d e f), %w(g h i)], ('a'..'i').to_a.in_groups_of(3)
   end
 
-  def test_group_by_with_padding
+  def test_in_groups_of_with_padding
     groups = []
     ('a'..'g').to_a.in_groups_of(3) do |group|
       groups << group
@@ -118,7 +118,7 @@ class ArrayExtGroupingTests < Test::Unit::TestCase
     assert_equal [%w(a b c), %w(d e f), ['g', nil, nil]], groups
   end
 
-  def test_group_by_pads_with_specified_values
+  def test_in_groups_of_pads_with_specified_values
     groups = []
 
     ('a'..'g').to_a.in_groups_of(3, 'foo') do |group|
@@ -128,7 +128,7 @@ class ArrayExtGroupingTests < Test::Unit::TestCase
     assert_equal [%w(a b c), %w(d e f), ['g', 'foo', 'foo']], groups
   end
 
-  def test_group_without_padding
+  def test_in_groups_of_without_padding
     groups = []
 
     ('a'..'g').to_a.in_groups_of(3, false) do |group|
@@ -137,6 +137,48 @@ class ArrayExtGroupingTests < Test::Unit::TestCase
 
     assert_equal [%w(a b c), %w(d e f), ['g']], groups
   end
+
+  def test_in_groups_returned_array_size
+    array = (1..7).to_a
+
+    1.upto(array.size + 1) do |number|
+      assert_equal number, array.in_groups(number).size
+    end
+  end
+
+  def test_in_groups_with_empty_array
+    assert_equal [[], [], []], [].in_groups(3)
+  end
+
+  def test_in_groups_with_block
+    array = (1..9).to_a
+    groups = []
+
+    array.in_groups(3) do |group|
+      groups << group
+    end
+
+    assert_equal array.in_groups(3), groups
+  end
+
+  def test_in_groups_with_perfect_fit
+    assert_equal [[1, 2, 3], [4, 5, 6], [7, 8, 9]],
+      (1..9).to_a.in_groups(3)
+  end
+
+  def test_in_groups_with_padding
+    array = (1..7).to_a
+
+    assert_equal [[1, 2, 3], [4, 5, nil], [6, 7, nil]],
+      array.in_groups(3)
+    assert_equal [[1, 2, 3], [4, 5, 'foo'], [6, 7, 'foo']],
+      array.in_groups(3, 'foo')
+  end
+
+  def test_in_groups_without_padding
+    assert_equal [[1, 2, 3], [4, 5], [6, 7]],
+      (1..7).to_a.in_groups(3, false)
+  end
 end
 
 class ArraySplitTests < Test::Unit::TestCase
-- 
1.5.5.3