From c685593e6e94fb4658cc3b6d3c0287951c7f7a9f Mon Sep 17 00:00:00 2001
From: Emir Pasic <emirpasic@hotmail.com>
Date: Wed, 22 Jun 2016 05:11:41 +0200
Subject: [PATCH] - rewrite enumerable operations using iterator (for easier
 copy/paste into other containers)

---
 lists/arraylist/arraylist.go | 68 ++++++++++++++++++++----------------
 1 file changed, 37 insertions(+), 31 deletions(-)

diff --git a/lists/arraylist/arraylist.go b/lists/arraylist/arraylist.go
index ff3f51d..c0e313f 100644
--- a/lists/arraylist/arraylist.go
+++ b/lists/arraylist/arraylist.go
@@ -178,33 +178,54 @@ func (list *List) Insert(index int, values ...interface{}) {
 	}
 }
 
+func (list *List) Iterator() Iterator {
+	return Iterator{list: list, current: -1}
+}
+
+func (iterator *Iterator) Next() bool {
+	iterator.current += 1
+	return iterator.list.withinRange(iterator.current)
+}
+
+func (iterator *Iterator) Value() interface{} {
+	return iterator.list.elements[iterator.current]
+}
+
+func (iterator *Iterator) Index() interface{} {
+	return iterator.current
+}
+
 func (list *List) Each(f func(index interface{}, value interface{})) {
-	for i := 0; i < list.size; i++ {
-		f(i, list.elements[i])
+	iterator := list.Iterator()
+	for iterator.Next() {
+		f(iterator.Index(), iterator.Value())
 	}
 }
 
 func (list *List) Map(f func(index interface{}, value interface{}) interface{}) containers.Container {
 	newList := &List{}
-	for i := 0; i < list.size; i++ {
-		newList.Add(f(i, list.elements[i]))
+	iterator := list.Iterator()
+	for iterator.Next() {
+		newList.Add(f(iterator.Index(), iterator.Value()))
 	}
 	return newList
 }
 
 func (list *List) Select(f func(index interface{}, value interface{}) bool) containers.Container {
 	newList := &List{}
-	for i := 0; i < list.size; i++ {
-		if f(i, list.elements[i]) {
-			newList.Add(list.elements[i])
+	iterator := list.Iterator()
+	for iterator.Next() {
+		if f(iterator.Index(), iterator.Value()) {
+			newList.Add(iterator.Value())
 		}
 	}
 	return newList
 }
 
 func (list *List) Any(f func(index interface{}, value interface{}) bool) bool {
-	for i := 0; i < list.size; i++ {
-		if f(i, list.elements[i]) {
+	iterator := list.Iterator()
+	for iterator.Next() {
+		if f(iterator.Index(), iterator.Value()) {
 			return true
 		}
 	}
@@ -212,8 +233,9 @@ func (list *List) Any(f func(index interface{}, value interface{}) bool) bool {
 }
 
 func (list *List) All(f func(index interface{}, value interface{}) bool) bool {
-	for i := 0; i < list.size; i++ {
-		if !f(i, list.elements[i]) {
+	iterator := list.Iterator()
+	for iterator.Next() {
+		if !f(iterator.Index(), iterator.Value()) {
 			return false
 		}
 	}
@@ -221,9 +243,10 @@ func (list *List) All(f func(index interface{}, value interface{}) bool) bool {
 }
 
 func (list *List) Find(f func(index interface{}, value interface{}) bool) (index interface{}, value interface{}) {
-	for i := 0; i < list.size; i++ {
-		if f(i, list.elements[i]) {
-			return i, list.elements[i]
+	iterator := list.Iterator()
+	for iterator.Next() {
+		if f(iterator.Index(), iterator.Value()) {
+			return iterator.Index(), iterator.Value()
 		}
 	}
 	return nil, nil
@@ -234,23 +257,6 @@ type Iterator struct {
 	current int
 }
 
-func (list *List) Iterator() Iterator {
-	return Iterator{list: list, current: -1}
-}
-
-func (iterator *Iterator) Next() bool {
-	iterator.current += 1
-	return iterator.list.withinRange(iterator.current)
-}
-
-func (iterator *Iterator) Value() interface{} {
-	return iterator.list.elements[iterator.current]
-}
-
-func (iterator *Iterator) Index() interface{} {
-	return iterator.current
-}
-
 func (list *List) String() string {
 	str := "ArrayList\n"
 	values := []string{}