container/list: slightly better code factoring

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/6569077

diff --git a/src/pkg/container/list/list.go b/src/pkg/container/list/list.go
index 17f5d17e695412dae2b3f3148434c26834c3936e..e29e3a79ac7c4c6f8908b487df384109cf4e159f 100644 (file)
--- a/src/pkg/container/list/list.go
+++ b/src/pkg/container/list/list.go
@@ -83,8 +83,7 @@ func (l *List) Back() *Element {
 // lazyInit lazily initializes a zero List value.
 func (l *List) lazyInit() {
        if l.root.next == nil {
-               l.root.next = &l.root
-               l.root.prev = &l.root
+               l.Init()
        }
 }
 
@@ -100,6 +99,11 @@ func (l *List) insert(e, at *Element) *Element {
        return e
 }
 
+// insertValue is a convenience wrapper for insert(&Element{Value: v}, at).
+func (l *List) insertValue(v interface{}, at *Element) *Element {
+       return l.insert(&Element{Value: v}, at)
+}
+
 // remove removes e from its list, decrements l.len, and returns e.
 func (l *List) remove(e *Element) *Element {
        e.prev.next = e.next
@@ -123,13 +127,13 @@ func (l *List) Remove(e *Element) interface{} {
 // Pushfront inserts a new element e with value v at the front of list l and returns e.
 func (l *List) PushFront(v interface{}) *Element {
        l.lazyInit()
-       return l.insert(&Element{Value: v}, &l.root)
+       return l.insertValue(v, &l.root)
 }
 
 // PushBack inserts a new element e with value v at the back of list l and returns e.
 func (l *List) PushBack(v interface{}) *Element {
        l.lazyInit()
-       return l.insert(&Element{Value: v}, l.root.prev)
+       return l.insertValue(v, l.root.prev)
 }
 
 // InsertBefore inserts a new element e with value v immediately before mark and returns e.
@@ -139,17 +143,17 @@ func (l *List) InsertBefore(v interface{}, mark *Element) *Element {
                return nil
        }
        // see comment in List.Remove about initialization of l
-       return l.insert(&Element{Value: v}, mark.prev)
+       return l.insertValue(v, mark.prev)
 }
 
 // InsertAfter inserts a new element e with value v immediately after mark and returns e.
 // If mark is not an element of l, the list is not modified.
-func (l *List) InsertAfter(value interface{}, mark *Element) *Element {
+func (l *List) InsertAfter(v interface{}, mark *Element) *Element {
        if mark.list != l {
                return nil
        }
        // see comment in List.Remove about initialization of l
-       return l.insert(&Element{Value: value}, mark)
+       return l.insertValue(v, mark)
 }
 
 // MoveToFront moves element e to the front of list l.
@@ -177,7 +181,7 @@ func (l *List) MoveToBack(e *Element) {
 func (l *List) PushBackList(other *List) {
        l.lazyInit()
        for i, e := other.Len(), other.Front(); i > 0; i, e = i-1, e.Next() {
-               l.insert(&Element{Value: e.Value}, l.root.prev)
+               l.insertValue(e.Value, l.root.prev)
        }
 }
 
@@ -186,6 +190,6 @@ func (l *List) PushBackList(other *List) {
 func (l *List) PushFrontList(other *List) {
        l.lazyInit()
        for i, e := other.Len(), other.Back(); i > 0; i, e = i-1, e.Prev() {
-               l.insert(&Element{Value: e.Value}, &l.root)
+               l.insertValue(e.Value, &l.root)
        }
 }