From 27ece9c76513a399fbddc85ee66df49f17e8c982 Mon Sep 17 00:00:00 2001
From: James Strachan <james.strachan@gmail.com>
Date: Wed, 29 Feb 2012 09:51:22 +0000
Subject: [PATCH] split the filter method into filter(predicate) and
 filterTo(result, predicate) for easier completion & avoid confusion - seems 2
 methods is better than the default arguments approach

---
 stdlib/ktSrc/Filter.kt        | 11 -----------
 stdlib/ktSrc/JavaIterables.kt | 12 +++++++++---
 2 files changed, 9 insertions(+), 14 deletions(-)

diff --git a/stdlib/ktSrc/Filter.kt b/stdlib/ktSrc/Filter.kt
index bf458ae0fb8..8c31626d436 100644
--- a/stdlib/ktSrc/Filter.kt
+++ b/stdlib/ktSrc/Filter.kt
@@ -8,17 +8,6 @@ Filters given iterator
 */
 inline fun <T> java.util.Iterator<T>.filter(f: (T)-> Boolean) : java.util.Iterator<T> = FilterIterator<T>(this, f)
 
-/*
-Adds filtered elements in to given container
-*/
-inline fun <T,U : Collection<in T>> java.lang.Iterable<T>.filterTo(var container: U, filter: (T)->Boolean) : U {
-   for(element in this) {
-      if(filter(element))
-        container.add(element)
-   }
-   return container
-}
-
 /*
 Create iterator filtering given java.lang.Iterable
 */
diff --git a/stdlib/ktSrc/JavaIterables.kt b/stdlib/ktSrc/JavaIterables.kt
index 9a63529c57c..c8ac5b970ab 100644
--- a/stdlib/ktSrc/JavaIterables.kt
+++ b/stdlib/ktSrc/JavaIterables.kt
@@ -41,8 +41,11 @@ inline fun <T> java.lang.Iterable<T>.find(predicate: (T)-> Boolean) : T? {
   return null
 }
 
-/** Returns a new collection containing all elements in this collection which match the given predicate */
-inline fun <T> java.lang.Iterable<T>.filter(result: Collection<T> = ArrayList<T>(), predicate: (T)-> Boolean) : Collection<T> {
+/** Returns a new List containing all elements in this collection which match the given predicate */
+inline fun <T> java.lang.Iterable<T>.filter(predicate: (T)-> Boolean) : Collection<T> = filterTo(java.util.ArrayList<T>(), predicate)
+
+/** Filters all elements in this collection which match the given predicate into the given result collection */
+inline fun <T, C: Collection<in T>> java.lang.Iterable<T>.filterTo(result: C, predicate: (T)-> Boolean) : C {
   for (elem in this) {
     if (predicate(elem))
       result.add(elem)
@@ -51,7 +54,10 @@ inline fun <T> java.lang.Iterable<T>.filter(result: Collection<T> = ArrayList<T>
 }
 
 /** Returns a new collection containing all elements in this collection which do not match the given predicate */
-inline fun <T> java.lang.Iterable<T>.filterNot(result: Collection<T> = ArrayList<T>(), predicate: (T)-> Boolean) : Collection<T> {
+inline fun <T> java.lang.Iterable<T>.filterNot(predicate: (T)-> Boolean) : Collection<T> =  filterNotTo(ArrayList<T>(), predicate)
+
+/** Returns a new collection containing all elements in this collection which do not match the given predicate */
+inline fun <T, C: Collection<in T>> java.lang.Iterable<T>.filterNotTo(result: C, predicate: (T)-> Boolean) : C {
   for (elem in this) {
     if (!predicate(elem))
       result.add(elem)