From 04b08da9af0c450d645ab7389d1467308cfc2db8 Mon Sep 17 00:00:00 2001 From: Michael Stapelberg Date: Mon, 4 Mar 2013 21:27:36 +0100 Subject: Imported Upstream version 1.1~hg20130304 --- src/pkg/container/heap/example_intheap_test.go | 43 +++++ src/pkg/container/heap/example_pq_test.go | 95 ++++++++++ src/pkg/container/heap/example_test.go | 105 ----------- src/pkg/container/heap/heap.go | 10 +- src/pkg/container/heap/heap_test.go | 16 +- src/pkg/container/list/example_test.go | 30 ++++ src/pkg/container/list/list.go | 238 ++++++++++++------------- src/pkg/container/list/list_test.go | 102 +++++++---- src/pkg/container/ring/ring.go | 2 +- 9 files changed, 364 insertions(+), 277 deletions(-) create mode 100644 src/pkg/container/heap/example_intheap_test.go create mode 100644 src/pkg/container/heap/example_pq_test.go delete mode 100644 src/pkg/container/heap/example_test.go create mode 100644 src/pkg/container/list/example_test.go (limited to 'src/pkg/container') diff --git a/src/pkg/container/heap/example_intheap_test.go b/src/pkg/container/heap/example_intheap_test.go new file mode 100644 index 000000000..e718cbc58 --- /dev/null +++ b/src/pkg/container/heap/example_intheap_test.go @@ -0,0 +1,43 @@ +// Copyright 2012 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// This example demonstrates an integer heap built using the heap interface. +package heap_test + +import ( + "container/heap" + "fmt" +) + +// An IntHeap is a min-heap of ints. +type IntHeap []int + +func (h IntHeap) Len() int { return len(h) } +func (h IntHeap) Less(i, j int) bool { return h[i] < h[j] } +func (h IntHeap) Swap(i, j int) { h[i], h[j] = h[j], h[i] } + +func (h *IntHeap) Push(x interface{}) { + // Push and Pop use pointer receivers because they modify the slice's length, + // not just its contents. + *h = append(*h, x.(int)) +} + +func (h *IntHeap) Pop() interface{} { + old := *h + n := len(old) + x := old[n-1] + *h = old[0 : n-1] + return x +} + +// This example inserts several ints into an IntHeap and removes them in order of priority. +func Example_intHeap() { + h := &IntHeap{2, 1, 5} + heap.Init(h) + heap.Push(h, 3) + for h.Len() > 0 { + fmt.Printf("%d ", heap.Pop(h)) + } + // Output: 1 2 3 5 +} diff --git a/src/pkg/container/heap/example_pq_test.go b/src/pkg/container/heap/example_pq_test.go new file mode 100644 index 000000000..8cbeb8d70 --- /dev/null +++ b/src/pkg/container/heap/example_pq_test.go @@ -0,0 +1,95 @@ +// Copyright 2012 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// This example demonstrates a priority queue built using the heap interface. +package heap_test + +import ( + "container/heap" + "fmt" +) + +// An Item is something we manage in a priority queue. +type Item struct { + value string // The value of the item; arbitrary. + priority int // The priority of the item in the queue. + // The index is needed by update and is maintained by the heap.Interface methods. + index int // The index of the item in the heap. +} + +// A PriorityQueue implements heap.Interface and holds Items. +type PriorityQueue []*Item + +func (pq PriorityQueue) Len() int { return len(pq) } + +func (pq PriorityQueue) Less(i, j int) bool { + // We want Pop to give us the highest, not lowest, priority so we use greater than here. + return pq[i].priority > pq[j].priority +} + +func (pq PriorityQueue) Swap(i, j int) { + pq[i], pq[j] = pq[j], pq[i] + pq[i].index = i + pq[j].index = j +} + +func (pq *PriorityQueue) Push(x interface{}) { + n := len(*pq) + item := x.(*Item) + item.index = n + *pq = append(*pq, item) +} + +func (pq *PriorityQueue) Pop() interface{} { + old := *pq + n := len(old) + item := old[n-1] + item.index = -1 // for safety + *pq = old[0 : n-1] + return item +} + +// update modifies the priority and value of an Item in the queue. +func (pq *PriorityQueue) update(item *Item, value string, priority int) { + heap.Remove(pq, item.index) + item.value = value + item.priority = priority + heap.Push(pq, item) +} + +// This example inserts some items into a PriorityQueue, manipulates an item, +// and then removes the items in priority order. +func Example_priorityQueue() { + // Some items and their priorities. + items := map[string]int{ + "banana": 3, "apple": 2, "pear": 4, + } + + // Create a priority queue and put the items in it. + pq := &PriorityQueue{} + heap.Init(pq) + for value, priority := range items { + item := &Item{ + value: value, + priority: priority, + } + heap.Push(pq, item) + } + + // Insert a new item and then modify its priority. + item := &Item{ + value: "orange", + priority: 1, + } + heap.Push(pq, item) + pq.update(item, item.value, 5) + + // Take the items out; they arrive in decreasing priority order. + for pq.Len() > 0 { + item := heap.Pop(pq).(*Item) + fmt.Printf("%.2d:%s ", item.priority, item.value) + } + // Output: + // 05:orange 04:pear 03:banana 02:apple +} diff --git a/src/pkg/container/heap/example_test.go b/src/pkg/container/heap/example_test.go deleted file mode 100644 index 2050bc835..000000000 --- a/src/pkg/container/heap/example_test.go +++ /dev/null @@ -1,105 +0,0 @@ -// Copyright 2012 The Go Authors. All rights reserved. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -// This example demonstrates a priority queue built using the heap interface. -package heap_test - -import ( - "container/heap" - "fmt" -) - -// An Item is something we manage in a priority queue. -type Item struct { - value string // The value of the item; arbitrary. - priority int // The priority of the item in the queue. - // The index is needed by changePriority and is maintained by the heap.Interface methods. - index int // The index of the item in the heap. -} - -// A PriorityQueue implements heap.Interface and holds Items. -type PriorityQueue []*Item - -func (pq PriorityQueue) Len() int { return len(pq) } - -func (pq PriorityQueue) Less(i, j int) bool { - // We want Pop to give us the highest, not lowest, priority so we use greater than here. - return pq[i].priority > pq[j].priority -} - -func (pq PriorityQueue) Swap(i, j int) { - pq[i], pq[j] = pq[j], pq[i] - pq[i].index = i - pq[j].index = j -} - -func (pq *PriorityQueue) Push(x interface{}) { - // Push and Pop use pointer receivers because they modify the slice's length, - // not just its contents. - // To simplify indexing expressions in these methods, we save a copy of the - // slice object. We could instead write (*pq)[i]. - a := *pq - n := len(a) - a = a[0 : n+1] - item := x.(*Item) - item.index = n - a[n] = item - *pq = a -} - -func (pq *PriorityQueue) Pop() interface{} { - a := *pq - n := len(a) - item := a[n-1] - item.index = -1 // for safety - *pq = a[0 : n-1] - return item -} - -// update is not used by the example but shows how to take the top item from -// the queue, update its priority and value, and put it back. -func (pq *PriorityQueue) update(value string, priority int) { - item := heap.Pop(pq).(*Item) - item.value = value - item.priority = priority - heap.Push(pq, item) -} - -// changePriority is not used by the example but shows how to change the -// priority of an arbitrary item. -func (pq *PriorityQueue) changePriority(item *Item, priority int) { - heap.Remove(pq, item.index) - item.priority = priority - heap.Push(pq, item) -} - -// This example pushes 10 items into a PriorityQueue and takes them out in -// order of priority. -func Example() { - const nItem = 10 - // Random priorities for the items (a permutation of 0..9, times 11)). - priorities := [nItem]int{ - 77, 22, 44, 55, 11, 88, 33, 99, 00, 66, - } - values := [nItem]string{ - "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", - } - // Create a priority queue and put some items in it. - pq := make(PriorityQueue, 0, nItem) - for i := 0; i < cap(pq); i++ { - item := &Item{ - value: values[i], - priority: priorities[i], - } - heap.Push(&pq, item) - } - // Take the items out; should arrive in decreasing priority order. - // For example, the highest priority (99) is the seventh item, so output starts with 99:"seven". - for i := 0; i < nItem; i++ { - item := heap.Pop(&pq).(*Item) - fmt.Printf("%.2d:%s ", item.priority, item.value) - } - // Output: - // 99:seven 88:five 77:zero 66:nine 55:three 44:two 33:six 22:one 11:four 00:eight -} diff --git a/src/pkg/container/heap/heap.go b/src/pkg/container/heap/heap.go index 67018e6ba..c37e50e3c 100644 --- a/src/pkg/container/heap/heap.go +++ b/src/pkg/container/heap/heap.go @@ -4,13 +4,13 @@ // Package heap provides heap operations for any type that implements // heap.Interface. A heap is a tree with the property that each node is the -// highest-valued node in its subtree. +// minimum-valued node in its subtree. // // A heap is a common way to implement a priority queue. To build a priority // queue, implement the Heap interface with the (negative) priority as the // ordering for the Less method, so Push adds items while Pop removes the // highest-priority item from the queue. The Examples include such an -// implementation; the file example_test.go has the complete source. +// implementation; the file example_pq_test.go has the complete source. // package heap @@ -79,7 +79,7 @@ func Remove(h Interface, i int) interface{} { func up(h Interface, j int) { for { i := (j - 1) / 2 // parent - if i == j || h.Less(i, j) { + if i == j || !h.Less(j, i) { break } h.Swap(i, j) @@ -90,14 +90,14 @@ func up(h Interface, j int) { func down(h Interface, i, n int) { for { j1 := 2*i + 1 - if j1 >= n { + if j1 >= n || j1 < 0 { // j1 < 0 after int overflow break } j := j1 // left child if j2 := j1 + 1; j2 < n && !h.Less(j1, j2) { j = j2 // = 2*i + 2 // right child } - if h.Less(i, j) { + if !h.Less(j, i) { break } h.Swap(i, j) diff --git a/src/pkg/container/heap/heap_test.go b/src/pkg/container/heap/heap_test.go index cb31ef6d3..274d587d8 100644 --- a/src/pkg/container/heap/heap_test.go +++ b/src/pkg/container/heap/heap_test.go @@ -2,10 +2,9 @@ // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. -package heap_test +package heap import ( - . "container/heap" "testing" ) @@ -170,3 +169,16 @@ func TestRemove2(t *testing.T) { } } } + +func BenchmarkDup(b *testing.B) { + const n = 10000 + h := make(myHeap, n) + for i := 0; i < b.N; i++ { + for j := 0; j < n; j++ { + Push(&h, 0) // all elements are the same + } + for h.Len() > 0 { + Pop(&h) + } + } +} diff --git a/src/pkg/container/list/example_test.go b/src/pkg/container/list/example_test.go new file mode 100644 index 000000000..7361212d7 --- /dev/null +++ b/src/pkg/container/list/example_test.go @@ -0,0 +1,30 @@ +// Copyright 2013 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package list_test + +import ( + "container/list" + "fmt" +) + +func Example() { + // Create a new list and put some numbers in it. + l := list.New() + e4 := l.PushBack(4) + e1 := l.PushFront(1) + l.InsertBefore(3, e4) + l.InsertAfter(2, e1) + + // Iterate through list and and print its contents. + for e := l.Front(); e != nil; e = e.Next() { + fmt.Println(e.Value) + } + + // Output: + // 1 + // 2 + // 3 + // 4 +} diff --git a/src/pkg/container/list/list.go b/src/pkg/container/list/list.go index a3fd4b39f..562a5badb 100644 --- a/src/pkg/container/list/list.go +++ b/src/pkg/container/list/list.go @@ -11,201 +11,187 @@ // package list -// Element is an element in the linked list. +// Element is an element of a linked list. type Element struct { // Next and previous pointers in the doubly-linked list of elements. - // The front of the list has prev = nil, and the back has next = nil. + // To simplify the implementation, internally a list l is implemented + // as a ring, such that &l.root is both the next element of the last + // list element (l.Back()) and the previous element of the first list + // element (l.Front()). next, prev *Element // The list to which this element belongs. list *List - // The contents of this list element. + // The value stored with this element. Value interface{} } // Next returns the next list element or nil. -func (e *Element) Next() *Element { return e.next } +func (e *Element) Next() *Element { + if p := e.next; p != &e.list.root { + return p + } + return nil +} // Prev returns the previous list element or nil. -func (e *Element) Prev() *Element { return e.prev } +func (e *Element) Prev() *Element { + if p := e.prev; p != &e.list.root { + return p + } + return nil +} // List represents a doubly linked list. // The zero value for List is an empty list ready to use. type List struct { - front, back *Element - len int + root Element // sentinel list element, only &root, root.prev, and root.next are used + len int // current list length excluding (this) sentinel element } -// Init initializes or clears a List. +// Init initializes or clears list l. func (l *List) Init() *List { - l.front = nil - l.back = nil + l.root.next = &l.root + l.root.prev = &l.root l.len = 0 return l } // New returns an initialized list. -func New() *List { return new(List) } - -// Front returns the first element in the list. -func (l *List) Front() *Element { return l.front } +func New() *List { return new(List).Init() } -// Back returns the last element in the list. -func (l *List) Back() *Element { return l.back } +// Len returns the number of elements of list l. +func (l *List) Len() int { return l.len } -// Remove removes the element from the list -// and returns its Value. -func (l *List) Remove(e *Element) interface{} { - l.remove(e) - e.list = nil // do what remove does not - return e.Value +// Front returns the first element of list l or nil +func (l *List) Front() *Element { + if l.len == 0 { + return nil + } + return l.root.next } -// remove the element from the list, but do not clear the Element's list field. -// This is so that other List methods may use remove when relocating Elements -// without needing to restore the list field. -func (l *List) remove(e *Element) { - if e.list != l { - return - } - if e.prev == nil { - l.front = e.next - } else { - e.prev.next = e.next - } - if e.next == nil { - l.back = e.prev - } else { - e.next.prev = e.prev +// Back returns the last element of list l or nil. +func (l *List) Back() *Element { + if l.len == 0 { + return nil } - - e.prev = nil - e.next = nil - l.len-- + return l.root.prev } -func (l *List) insertBefore(e *Element, mark *Element) { - if mark.prev == nil { - // new front of the list - l.front = e - } else { - mark.prev.next = e +// lazyInit lazily initializes a zero List value. +func (l *List) lazyInit() { + if l.root.next == nil { + l.Init() } - e.prev = mark.prev - mark.prev = e - e.next = mark - l.len++ } -func (l *List) insertAfter(e *Element, mark *Element) { - if mark.next == nil { - // new back of the list - l.back = e - } else { - mark.next.prev = e - } - e.next = mark.next - mark.next = e - e.prev = mark +// insert inserts e after at, increments l.len, and returns e. +func (l *List) insert(e, at *Element) *Element { + n := at.next + at.next = e + e.prev = at + e.next = n + n.prev = e + e.list = l l.len++ + return e } -func (l *List) insertFront(e *Element) { - if l.front == nil { - // empty list - l.front, l.back = e, e - e.prev, e.next = nil, nil - l.len = 1 - return - } - l.insertBefore(e, l.front) +// 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) } -func (l *List) insertBack(e *Element) { - if l.back == nil { - // empty list - l.front, l.back = e, e - e.prev, e.next = nil, nil - l.len = 1 - return +// remove removes e from its list, decrements l.len, and returns e. +func (l *List) remove(e *Element) *Element { + e.prev.next = e.next + e.next.prev = e.prev + e.next = nil // avoid memory leaks + e.prev = nil // avoid memory leaks + e.list = nil + l.len-- + return e +} + +// Remove removes e from l if e is an element of list l. +// It returns the element value e.Value. +func (l *List) Remove(e *Element) interface{} { + if e.list == l { + // if e.list == l, l must have been initialized when e was inserted + // in l or l == nil (e is a zero Element) and l.remove will crash + l.remove(e) } - l.insertAfter(e, l.back) + return e.Value } -// PushFront inserts the value at the front of the list and returns a new Element containing the value. -func (l *List) PushFront(value interface{}) *Element { - e := &Element{nil, nil, l, value} - l.insertFront(e) - return e +// 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.insertValue(v, &l.root) } -// PushBack inserts the value at the back of the list and returns a new Element containing the value. -func (l *List) PushBack(value interface{}) *Element { - e := &Element{nil, nil, l, value} - l.insertBack(e) - return e +// 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.insertValue(v, l.root.prev) } -// InsertBefore inserts the value immediately before mark and returns a new Element containing the value. -func (l *List) InsertBefore(value interface{}, mark *Element) *Element { +// InsertBefore inserts a new element e with value v immediately before mark and returns e. +// If mark is not an element of l, the list is not modified. +func (l *List) InsertBefore(v interface{}, mark *Element) *Element { if mark.list != l { return nil } - e := &Element{nil, nil, l, value} - l.insertBefore(e, mark) - return e + // see comment in List.Remove about initialization of l + return l.insertValue(v, mark.prev) } -// InsertAfter inserts the value immediately after mark and returns a new Element containing the value. -func (l *List) InsertAfter(value interface{}, mark *Element) *Element { +// 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(v interface{}, mark *Element) *Element { if mark.list != l { return nil } - e := &Element{nil, nil, l, value} - l.insertAfter(e, mark) - return e + // see comment in List.Remove about initialization of l + return l.insertValue(v, mark) } -// MoveToFront moves the element to the front of the list. +// MoveToFront moves element e to the front of list l. +// If e is not an element of l, the list is not modified. func (l *List) MoveToFront(e *Element) { - if e.list != l || l.front == e { + if e.list != l || l.root.next == e { return } - l.remove(e) - l.insertFront(e) + // see comment in List.Remove about initialization of l + l.insert(l.remove(e), &l.root) } -// MoveToBack moves the element to the back of the list. +// MoveToBack moves element e to the back of list l. +// If e is not an element of l, the list is not modified. func (l *List) MoveToBack(e *Element) { - if e.list != l || l.back == e { + if e.list != l || l.root.prev == e { return } - l.remove(e) - l.insertBack(e) + // see comment in List.Remove about initialization of l + l.insert(l.remove(e), l.root.prev) } -// Len returns the number of elements in the list. -func (l *List) Len() int { return l.len } - -// PushBackList inserts each element of ol at the back of the list. -func (l *List) PushBackList(ol *List) { - last := ol.Back() - for e := ol.Front(); e != nil; e = e.Next() { - l.PushBack(e.Value) - if e == last { - break - } +// PushBackList inserts a copy of an other list at the back of list l. +// The lists l and other may be the same. +func (l *List) PushBackList(other *List) { + l.lazyInit() + for i, e := other.Len(), other.Front(); i > 0; i, e = i-1, e.Next() { + l.insertValue(e.Value, l.root.prev) } } -// PushFrontList inserts each element of ol at the front of the list. The ordering of the passed list is preserved. -func (l *List) PushFrontList(ol *List) { - first := ol.Front() - for e := ol.Back(); e != nil; e = e.Prev() { - l.PushFront(e.Value) - if e == first { - break - } +// PushFrontList inserts a copy of an other list at the front of list l. +// The lists l and other may be the same. +func (l *List) PushFrontList(other *List) { + l.lazyInit() + for i, e := other.Len(), other.Back(); i > 0; i, e = i-1, e.Prev() { + l.insertValue(e.Value, &l.root) } } diff --git a/src/pkg/container/list/list_test.go b/src/pkg/container/list/list_test.go index 1d44ff84e..b4fc77d14 100644 --- a/src/pkg/container/list/list_test.go +++ b/src/pkg/container/list/list_test.go @@ -4,65 +4,75 @@ package list -import ( - "testing" -) +import "testing" + +func checkListLen(t *testing.T, l *List, len int) bool { + if n := l.Len(); n != len { + t.Errorf("l.Len() = %d, want %d", n, len) + return false + } + return true +} func checkListPointers(t *testing.T, l *List, es []*Element) { - if len(es) == 0 { - if l.front != nil || l.back != nil { - t.Errorf("l.front/l.back = %v/%v should be nil/nil", l.front, l.back) - } + root := &l.root + + if !checkListLen(t, l, len(es)) { return } - if l.front != es[0] { - t.Errorf("l.front = %v, want %v", l.front, es[0]) - } - if last := es[len(es)-1]; l.back != last { - t.Errorf("l.back = %v, want %v", l.back, last) + // zero length lists must be the zero value or properly initialized (sentinel circle) + if len(es) == 0 { + if l.root.next != nil && l.root.next != root || l.root.prev != nil && l.root.prev != root { + t.Errorf("l.root.next = %p, l.root.prev = %p; both should both be nil or %p", l.root.next, l.root.prev, root) + } + return } + // len(es) > 0 + // check internal and external prev/next connections for i, e := range es { - var e_prev, e_next *Element = nil, nil + prev := root + Prev := (*Element)(nil) if i > 0 { - e_prev = es[i-1] + prev = es[i-1] + Prev = prev + } + if p := e.prev; p != prev { + t.Errorf("elt[%d](%p).prev = %p, want %p", i, e, p, prev) + } + if p := e.Prev(); p != Prev { + t.Errorf("elt[%d](%p).Prev() = %p, want %p", i, e, p, Prev) } + + next := root + Next := (*Element)(nil) if i < len(es)-1 { - e_next = es[i+1] + next = es[i+1] + Next = next } - if e.prev != e_prev { - t.Errorf("elt #%d (%v) has prev=%v, want %v", i, e, e.prev, e_prev) + if n := e.next; n != next { + t.Errorf("elt[%d](%p).next = %p, want %p", i, e, n, next) } - if e.next != e_next { - t.Errorf("elt #%d (%v) has next=%v, want %v", i, e, e.next, e_next) + if n := e.Next(); n != Next { + t.Errorf("elt[%d](%p).Next() = %p, want %p", i, e, n, Next) } } } -func checkListLen(t *testing.T, l *List, n int) { - if an := l.Len(); an != n { - t.Errorf("l.Len() = %d, want %d", an, n) - } -} - func TestList(t *testing.T) { l := New() checkListPointers(t, l, []*Element{}) - checkListLen(t, l, 0) // Single element list e := l.PushFront("a") - checkListLen(t, l, 1) checkListPointers(t, l, []*Element{e}) l.MoveToFront(e) checkListPointers(t, l, []*Element{e}) l.MoveToBack(e) checkListPointers(t, l, []*Element{e}) - checkListLen(t, l, 1) l.Remove(e) checkListPointers(t, l, []*Element{}) - checkListLen(t, l, 0) // Bigger list e2 := l.PushFront(2) @@ -70,11 +80,9 @@ func TestList(t *testing.T) { e3 := l.PushBack(3) e4 := l.PushBack("banana") checkListPointers(t, l, []*Element{e1, e2, e3, e4}) - checkListLen(t, l, 4) l.Remove(e2) checkListPointers(t, l, []*Element{e1, e3, e4}) - checkListLen(t, l, 3) l.MoveToFront(e3) // move from middle checkListPointers(t, l, []*Element{e3, e1, e4}) @@ -121,7 +129,7 @@ func TestList(t *testing.T) { } } if sum != 4 { - t.Errorf("sum over l.Iter() = %d, want 4", sum) + t.Errorf("sum over l = %d, want 4", sum) } // Clear all elements by iterating @@ -131,19 +139,18 @@ func TestList(t *testing.T) { l.Remove(e) } checkListPointers(t, l, []*Element{}) - checkListLen(t, l, 0) } func checkList(t *testing.T, l *List, es []interface{}) { - if l.Len() != len(es) { - t.Errorf("list has len=%v, want %v", l.Len(), len(es)) + if !checkListLen(t, l, len(es)) { return } + i := 0 for e := l.Front(); e != nil; e = e.Next() { le := e.Value.(int) if le != es[i] { - t.Errorf("elt #%d has value=%v, want %v", i, le, es[i]) + t.Errorf("elt[%d].Value = %v, want %v", i, le, es[i]) } i++ } @@ -202,8 +209,27 @@ func TestRemove(t *testing.T) { e := l.Front() l.Remove(e) checkListPointers(t, l, []*Element{e2}) - checkListLen(t, l, 1) l.Remove(e) checkListPointers(t, l, []*Element{e2}) - checkListLen(t, l, 1) +} + +func TestIssue4103(t *testing.T) { + l1 := New() + l1.PushBack(1) + l1.PushBack(2) + + l2 := New() + l2.PushBack(3) + l2.PushBack(4) + + e := l1.Front() + l2.Remove(e) // l2 should not change because e is not an element of l2 + if n := l2.Len(); n != 2 { + t.Errorf("l2.Len() = %d, want 2", n) + } + + l1.InsertBefore(8, e) + if n := l1.Len(); n != 3 { + t.Errorf("l1.Len() = %d, want 3", n) + } } diff --git a/src/pkg/container/ring/ring.go b/src/pkg/container/ring/ring.go index 1d96918d3..6d3b3e5b3 100644 --- a/src/pkg/container/ring/ring.go +++ b/src/pkg/container/ring/ring.go @@ -74,7 +74,7 @@ func New(n int) *Ring { return r } -// Link connects ring r with with ring s such that r.Next() +// Link connects ring r with ring s such that r.Next() // becomes s and returns the original value for r.Next(). // r must not be empty. // -- cgit v1.2.3