From c816bab14bcf6bcfcac7766817e7b8155e3b8525 Mon Sep 17 00:00:00 2001
From: joey schoblaska <joey@appkiln.com>
Date: Sat, 25 Jul 2009 17:33:50 -0500
Subject: [PATCH] added Array.uniq_by to core_ext

---
 activesupport/lib/active_support/core_ext/array.rb |    1 +
 .../lib/active_support/core_ext/array/uniq_by.rb   |   14 ++++++++++++
 activesupport/test/core_ext/array_ext_test.rb      |   22 ++++++++++++++++++++
 3 files changed, 37 insertions(+), 0 deletions(-)
 create mode 100644 activesupport/lib/active_support/core_ext/array/uniq_by.rb

diff --git a/activesupport/lib/active_support/core_ext/array.rb b/activesupport/lib/active_support/core_ext/array.rb
index b583c75..aeac7a9 100644
--- a/activesupport/lib/active_support/core_ext/array.rb
+++ b/activesupport/lib/active_support/core_ext/array.rb
@@ -4,3 +4,4 @@ require 'active_support/core_ext/array/conversions'
 require 'active_support/core_ext/array/extract_options'
 require 'active_support/core_ext/array/grouping'
 require 'active_support/core_ext/array/random_access'
+require 'active_support/core_ext/array/uniq_by'
\ No newline at end of file
diff --git a/activesupport/lib/active_support/core_ext/array/uniq_by.rb b/activesupport/lib/active_support/core_ext/array/uniq_by.rb
new file mode 100644
index 0000000..72d058e
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/array/uniq_by.rb
@@ -0,0 +1,14 @@
+class Array
+  
+  # Select unique elements based on their response to a proc
+  def uniq_by(proc)
+    select{ |item| select{|i| proc.call(i) == proc.call(item)}.index(item) == 0 }
+  end
+  
+  # Select unique elements based on their response to a proc
+  def uniq_by!(proc)
+    uniq_by_items = uniq_by(proc)
+    reject!{|item| !uniq_by_items.include?(item)}
+  end
+  
+end
\ No newline at end of file
diff --git a/activesupport/test/core_ext/array_ext_test.rb b/activesupport/test/core_ext/array_ext_test.rb
index 24d3389..ab28a81 100644
--- a/activesupport/test/core_ext/array_ext_test.rb
+++ b/activesupport/test/core_ext/array_ext_test.rb
@@ -358,3 +358,25 @@ class ArrayWrapperTests < Test::Unit::TestCase
     assert_equal ["foo", "bar"], Array.wrap(FakeCollection.new)
   end
 end
+
+class ArrayUniqByTests < Test::Unit::TestCase
+  def test_uniq_by
+    array = [{:id => 1, :val => 1}, 
+             {:id => 2, :val => 1},
+             {:id => 3, :val => 2},
+             {:id => 4, :val => 3}]
+             
+    assert_equal array.uniq_by(Proc.new {|a| a[:val]}).map{|a| a[:id]}, [1,3,4]
+  end
+  
+  def test_uniq_by_bang
+    array = [{:id => 1, :val => 1}, 
+             {:id => 2, :val => 1},
+             {:id => 3, :val => 2},
+             {:id => 4, :val => 3}]
+             
+    array.uniq_by!(Proc.new {|a| a[:val]})
+             
+    assert_equal array.map{|a| a[:id]}, [1,3,4]
+  end
+end
\ No newline at end of file
-- 
1.6.3.3