1 files changed, 608 insertions, 0 deletions
diff --git a/test/typeparam/list2.go b/test/typeparam/list2.go
new file mode 100644
index 0000000..111ac78
--- /dev/null
+++ b/test/typeparam/list2.go
@@ -0,0 +1,608 @@
+// run
+
+// Copyright 2021 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 provides a doubly linked list of some element type
+// (generic form of the "container/list" package).
+
+package main
+
+import (
+	"fmt"
+	"strconv"
+)
+
+// Element is an element of a linked list.
+type _Element[T any] struct {
+	// Next and previous pointers in the doubly-linked list of elements.
+	// 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[T]
+
+	// The list to which this element belongs.
+	list *_List[T]
+
+	// The value stored with this element.
+	Value T
+}
+
+// Next returns the next list element or nil.
+func (e *_Element[T]) Next() *_Element[T] {
+	if p := e.next; e.list != nil && p != &e.list.root {
+		return p
+	}
+	return nil
+}
+
+// Prev returns the previous list element or nil.
+func (e *_Element[T]) Prev() *_Element[T] {
+	if p := e.prev; e.list != nil && 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[T any] struct {
+	root _Element[T] // 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 list l.
+func (l *_List[T]) Init() *_List[T] {
+	l.root.next = &l.root
+	l.root.prev = &l.root
+	l.len = 0
+	return l
+}
+
+// New returns an initialized list.
+func _New[T any]() *_List[T] { return new(_List[T]).Init() }
+
+// Len returns the number of elements of list l.
+// The complexity is O(1).
+func (l *_List[_]) Len() int { return l.len }
+
+// Front returns the first element of list l or nil if the list is empty.
+func (l *_List[T]) Front() *_Element[T] {
+	if l.len == 0 {
+		return nil
+	}
+	return l.root.next
+}
+
+// Back returns the last element of list l or nil if the list is empty.
+func (l *_List[T]) Back() *_Element[T] {
+	if l.len == 0 {
+		return nil
+	}
+	return l.root.prev
+}
+
+// lazyInit lazily initializes a zero _List value.
+func (l *_List[_]) lazyInit() {
+	if l.root.next == nil {
+		l.Init()
+	}
+}
+
+// insert inserts e after at, increments l.len, and returns e.
+func (l *_List[T]) insert(e, at *_Element[T]) *_Element[T] {
+	e.prev = at
+	e.next = at.next
+	e.prev.next = e
+	e.next.prev = e
+	e.list = l
+	l.len++
+	return e
+}
+
+// insertValue is a convenience wrapper for insert(&_Element[T]{Value: v}, at).
+func (l *_List[T]) insertValue(v T, at *_Element[T]) *_Element[T] {
+	return l.insert(&_Element[T]{Value: v}, at)
+}
+
+// remove removes e from its list, decrements l.len, and returns e.
+func (l *_List[T]) remove(e *_Element[T]) *_Element[T] {
+	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
+}
+
+// move moves e to next to at and returns e.
+func (l *_List[T]) move(e, at *_Element[T]) *_Element[T] {
+	if e == at {
+		return e
+	}
+	e.prev.next = e.next
+	e.next.prev = e.prev
+
+	e.prev = at
+	e.next = at.next
+	e.prev.next = e
+	e.next.prev = e
+
+	return e
+}
+
+// Remove removes e from l if e is an element of list l.
+// It returns the element value e.Value.
+// The element must not be nil.
+func (l *_List[T]) Remove(e *_Element[T]) T {
+	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)
+	}
+	return e.Value
+}
+
+// PushFront inserts a new element e with value v at the front of list l and returns e.
+func (l *_List[T]) PushFront(v T) *_Element[T] {
+	l.lazyInit()
+	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[T]) PushBack(v T) *_Element[T] {
+	l.lazyInit()
+	return l.insertValue(v, l.root.prev)
+}
+
+// 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.
+// The mark must not be nil.
+func (l *_List[T]) InsertBefore(v T, mark *_Element[T]) *_Element[T] {
+	if mark.list != l {
+		return nil
+	}
+	// see comment in _List.Remove about initialization of l
+	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.
+// The mark must not be nil.
+func (l *_List[T]) InsertAfter(v T, mark *_Element[T]) *_Element[T] {
+	if mark.list != l {
+		return nil
+	}
+	// see comment in _List.Remove about initialization of l
+	return l.insertValue(v, mark)
+}
+
+// MoveToFront moves element e to the front of list l.
+// If e is not an element of l, the list is not modified.
+// The element must not be nil.
+func (l *_List[T]) MoveToFront(e *_Element[T]) {
+	if e.list != l || l.root.next == e {
+		return
+	}
+	// see comment in _List.Remove about initialization of l
+	l.move(e, &l.root)
+}
+
+// MoveToBack moves element e to the back of list l.
+// If e is not an element of l, the list is not modified.
+// The element must not be nil.
+func (l *_List[T]) MoveToBack(e *_Element[T]) {
+	if e.list != l || l.root.prev == e {
+		return
+	}
+	// see comment in _List.Remove about initialization of l
+	l.move(e, l.root.prev)
+}
+
+// MoveBefore moves element e to its new position before mark.
+// If e or mark is not an element of l, or e == mark, the list is not modified.
+// The element and mark must not be nil.
+func (l *_List[T]) MoveBefore(e, mark *_Element[T]) {
+	if e.list != l || e == mark || mark.list != l {
+		return
+	}
+	l.move(e, mark.prev)
+}
+
+// MoveAfter moves element e to its new position after mark.
+// If e or mark is not an element of l, or e == mark, the list is not modified.
+// The element and mark must not be nil.
+func (l *_List[T]) MoveAfter(e, mark *_Element[T]) {
+	if e.list != l || e == mark || mark.list != l {
+		return
+	}
+	l.move(e, mark)
+}
+
+// PushBackList inserts a copy of an other list at the back of list l.
+// The lists l and other may be the same. They must not be nil.
+func (l *_List[T]) PushBackList(other *_List[T]) {
+	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 a copy of an other list at the front of list l.
+// The lists l and other may be the same. They must not be nil.
+func (l *_List[T]) PushFrontList(other *_List[T]) {
+	l.lazyInit()
+	for i, e := other.Len(), other.Back(); i > 0; i, e = i-1, e.Prev() {
+		l.insertValue(e.Value, &l.root)
+	}
+}
+
+// Transform runs a transform function on a list returning a new list.
+func _Transform[TElem1, TElem2 any](lst *_List[TElem1], f func(TElem1) TElem2) *_List[TElem2] {
+	ret := _New[TElem2]()
+	for p := lst.Front(); p != nil; p = p.Next() {
+		ret.PushBack(f(p.Value))
+	}
+	return ret
+}
+
+func checkListLen[T any](l *_List[T], len int) bool {
+	if n := l.Len(); n != len {
+		panic(fmt.Sprintf("l.Len() = %d, want %d", n, len))
+		return false
+	}
+	return true
+}
+
+func checkListPointers[T any](l *_List[T], es []*_Element[T]) {
+	root := &l.root
+
+	if !checkListLen(l, len(es)) {
+		return
+	}
+
+	// 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 {
+			panic(fmt.Sprintf("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 {
+		prev := root
+		Prev := (*_Element[T])(nil)
+		if i > 0 {
+			prev = es[i-1]
+			Prev = prev
+		}
+		if p := e.prev; p != prev {
+			panic(fmt.Sprintf("elt[%d](%p).prev = %p, want %p", i, e, p, prev))
+		}
+		if p := e.Prev(); p != Prev {
+			panic(fmt.Sprintf("elt[%d](%p).Prev() = %p, want %p", i, e, p, Prev))
+		}
+
+		next := root
+		Next := (*_Element[T])(nil)
+		if i < len(es)-1 {
+			next = es[i+1]
+			Next = next
+		}
+		if n := e.next; n != next {
+			panic(fmt.Sprintf("elt[%d](%p).next = %p, want %p", i, e, n, next))
+		}
+		if n := e.Next(); n != Next {
+			panic(fmt.Sprintf("elt[%d](%p).Next() = %p, want %p", i, e, n, Next))
+		}
+	}
+}
+
+func TestList() {
+	l := _New[string]()
+	checkListPointers(l, []*(_Element[string]){})
+
+	// Single element list
+	e := l.PushFront("a")
+	checkListPointers(l, []*(_Element[string]){e})
+	l.MoveToFront(e)
+	checkListPointers(l, []*(_Element[string]){e})
+	l.MoveToBack(e)
+	checkListPointers(l, []*(_Element[string]){e})
+	l.Remove(e)
+	checkListPointers(l, []*(_Element[string]){})
+
+	// Bigger list
+	l2 := _New[int]()
+	e2 := l2.PushFront(2)
+	e1 := l2.PushFront(1)
+	e3 := l2.PushBack(3)
+	e4 := l2.PushBack(600)
+	checkListPointers(l2, []*(_Element[int]){e1, e2, e3, e4})
+
+	l2.Remove(e2)
+	checkListPointers(l2, []*(_Element[int]){e1, e3, e4})
+
+	l2.MoveToFront(e3) // move from middle
+	checkListPointers(l2, []*(_Element[int]){e3, e1, e4})
+
+	l2.MoveToFront(e1)
+	l2.MoveToBack(e3) // move from middle
+	checkListPointers(l2, []*(_Element[int]){e1, e4, e3})
+
+	l2.MoveToFront(e3) // move from back
+	checkListPointers(l2, []*(_Element[int]){e3, e1, e4})
+	l2.MoveToFront(e3) // should be no-op
+	checkListPointers(l2, []*(_Element[int]){e3, e1, e4})
+
+	l2.MoveToBack(e3) // move from front
+	checkListPointers(l2, []*(_Element[int]){e1, e4, e3})
+	l2.MoveToBack(e3) // should be no-op
+	checkListPointers(l2, []*(_Element[int]){e1, e4, e3})
+
+	e2 = l2.InsertBefore(2, e1) // insert before front
+	checkListPointers(l2, []*(_Element[int]){e2, e1, e4, e3})
+	l2.Remove(e2)
+	e2 = l2.InsertBefore(2, e4) // insert before middle
+	checkListPointers(l2, []*(_Element[int]){e1, e2, e4, e3})
+	l2.Remove(e2)
+	e2 = l2.InsertBefore(2, e3) // insert before back
+	checkListPointers(l2, []*(_Element[int]){e1, e4, e2, e3})
+	l2.Remove(e2)
+
+	e2 = l2.InsertAfter(2, e1) // insert after front
+	checkListPointers(l2, []*(_Element[int]){e1, e2, e4, e3})
+	l2.Remove(e2)
+	e2 = l2.InsertAfter(2, e4) // insert after middle
+	checkListPointers(l2, []*(_Element[int]){e1, e4, e2, e3})
+	l2.Remove(e2)
+	e2 = l2.InsertAfter(2, e3) // insert after back
+	checkListPointers(l2, []*(_Element[int]){e1, e4, e3, e2})
+	l2.Remove(e2)
+
+	// Check standard iteration.
+	sum := 0
+	for e := l2.Front(); e != nil; e = e.Next() {
+		sum += e.Value
+	}
+	if sum != 604 {
+		panic(fmt.Sprintf("sum over l = %d, want 604", sum))
+	}
+
+	// Clear all elements by iterating
+	var next *_Element[int]
+	for e := l2.Front(); e != nil; e = next {
+		next = e.Next()
+		l2.Remove(e)
+	}
+	checkListPointers(l2, []*(_Element[int]){})
+}
+
+func checkList[T comparable](l *_List[T], es []interface{}) {
+	if !checkListLen(l, len(es)) {
+		return
+	}
+
+	i := 0
+	for e := l.Front(); e != nil; e = e.Next() {
+		le := e.Value
+		// Comparison between a generically-typed variable le and an interface.
+		if le != es[i] {
+			panic(fmt.Sprintf("elt[%d].Value = %v, want %v", i, le, es[i]))
+		}
+		i++
+	}
+}
+
+func TestExtending() {
+	l1 := _New[int]()
+	l2 := _New[int]()
+
+	l1.PushBack(1)
+	l1.PushBack(2)
+	l1.PushBack(3)
+
+	l2.PushBack(4)
+	l2.PushBack(5)
+
+	l3 := _New[int]()
+	l3.PushBackList(l1)
+	checkList(l3, []interface{}{1, 2, 3})
+	l3.PushBackList(l2)
+	checkList(l3, []interface{}{1, 2, 3, 4, 5})
+
+	l3 = _New[int]()
+	l3.PushFrontList(l2)
+	checkList(l3, []interface{}{4, 5})
+	l3.PushFrontList(l1)
+	checkList(l3, []interface{}{1, 2, 3, 4, 5})
+
+	checkList(l1, []interface{}{1, 2, 3})
+	checkList(l2, []interface{}{4, 5})
+
+	l3 = _New[int]()
+	l3.PushBackList(l1)
+	checkList(l3, []interface{}{1, 2, 3})
+	l3.PushBackList(l3)
+	checkList(l3, []interface{}{1, 2, 3, 1, 2, 3})
+
+	l3 = _New[int]()
+	l3.PushFrontList(l1)
+	checkList(l3, []interface{}{1, 2, 3})
+	l3.PushFrontList(l3)
+	checkList(l3, []interface{}{1, 2, 3, 1, 2, 3})
+
+	l3 = _New[int]()
+	l1.PushBackList(l3)
+	checkList(l1, []interface{}{1, 2, 3})
+	l1.PushFrontList(l3)
+	checkList(l1, []interface{}{1, 2, 3})
+}
+
+func TestRemove() {
+	l := _New[int]()
+	e1 := l.PushBack(1)
+	e2 := l.PushBack(2)
+	checkListPointers(l, []*(_Element[int]){e1, e2})
+	e := l.Front()
+	l.Remove(e)
+	checkListPointers(l, []*(_Element[int]){e2})
+	l.Remove(e)
+	checkListPointers(l, []*(_Element[int]){e2})
+}
+
+func TestIssue4103() {
+	l1 := _New[int]()
+	l1.PushBack(1)
+	l1.PushBack(2)
+
+	l2 := _New[int]()
+	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 {
+		panic(fmt.Sprintf("l2.Len() = %d, want 2", n))
+	}
+
+	l1.InsertBefore(8, e)
+	if n := l1.Len(); n != 3 {
+		panic(fmt.Sprintf("l1.Len() = %d, want 3", n))
+	}
+}
+
+func TestIssue6349() {
+	l := _New[int]()
+	l.PushBack(1)
+	l.PushBack(2)
+
+	e := l.Front()
+	l.Remove(e)
+	if e.Value != 1 {
+		panic(fmt.Sprintf("e.value = %d, want 1", e.Value))
+	}
+	if e.Next() != nil {
+		panic(fmt.Sprintf("e.Next() != nil"))
+	}
+	if e.Prev() != nil {
+		panic(fmt.Sprintf("e.Prev() != nil"))
+	}
+}
+
+func TestMove() {
+	l := _New[int]()
+	e1 := l.PushBack(1)
+	e2 := l.PushBack(2)
+	e3 := l.PushBack(3)
+	e4 := l.PushBack(4)
+
+	l.MoveAfter(e3, e3)
+	checkListPointers(l, []*(_Element[int]){e1, e2, e3, e4})
+	l.MoveBefore(e2, e2)
+	checkListPointers(l, []*(_Element[int]){e1, e2, e3, e4})
+
+	l.MoveAfter(e3, e2)
+	checkListPointers(l, []*(_Element[int]){e1, e2, e3, e4})
+	l.MoveBefore(e2, e3)
+	checkListPointers(l, []*(_Element[int]){e1, e2, e3, e4})
+
+	l.MoveBefore(e2, e4)
+	checkListPointers(l, []*(_Element[int]){e1, e3, e2, e4})
+	e2, e3 = e3, e2
+
+	l.MoveBefore(e4, e1)
+	checkListPointers(l, []*(_Element[int]){e4, e1, e2, e3})
+	e1, e2, e3, e4 = e4, e1, e2, e3
+
+	l.MoveAfter(e4, e1)
+	checkListPointers(l, []*(_Element[int]){e1, e4, e2, e3})
+	e2, e3, e4 = e4, e2, e3
+
+	l.MoveAfter(e2, e3)
+	checkListPointers(l, []*(_Element[int]){e1, e3, e2, e4})
+	e2, e3 = e3, e2
+}
+
+// Test PushFront, PushBack, PushFrontList, PushBackList with uninitialized _List
+func TestZeroList() {
+	var l1 = new(_List[int])
+	l1.PushFront(1)
+	checkList(l1, []interface{}{1})
+
+	var l2 = new(_List[int])
+	l2.PushBack(1)
+	checkList(l2, []interface{}{1})
+
+	var l3 = new(_List[int])
+	l3.PushFrontList(l1)
+	checkList(l3, []interface{}{1})
+
+	var l4 = new(_List[int])
+	l4.PushBackList(l2)
+	checkList(l4, []interface{}{1})
+}
+
+// Test that a list l is not modified when calling InsertBefore with a mark that is not an element of l.
+func TestInsertBeforeUnknownMark() {
+	var l _List[int]
+	l.PushBack(1)
+	l.PushBack(2)
+	l.PushBack(3)
+	l.InsertBefore(1, new(_Element[int]))
+	checkList(&l, []interface{}{1, 2, 3})
+}
+
+// Test that a list l is not modified when calling InsertAfter with a mark that is not an element of l.
+func TestInsertAfterUnknownMark() {
+	var l _List[int]
+	l.PushBack(1)
+	l.PushBack(2)
+	l.PushBack(3)
+	l.InsertAfter(1, new(_Element[int]))
+	checkList(&l, []interface{}{1, 2, 3})
+}
+
+// Test that a list l is not modified when calling MoveAfter or MoveBefore with a mark that is not an element of l.
+func TestMoveUnknownMark() {
+	var l1 _List[int]
+	e1 := l1.PushBack(1)
+
+	var l2 _List[int]
+	e2 := l2.PushBack(2)
+
+	l1.MoveAfter(e1, e2)
+	checkList(&l1, []interface{}{1})
+	checkList(&l2, []interface{}{2})
+
+	l1.MoveBefore(e1, e2)
+	checkList(&l1, []interface{}{1})
+	checkList(&l2, []interface{}{2})
+}
+
+// Test the Transform function.
+func TestTransform() {
+	l1 := _New[int]()
+	l1.PushBack(1)
+	l1.PushBack(2)
+	l2 := _Transform(l1, strconv.Itoa)
+	checkList(l2, []interface{}{"1", "2"})
+}
+
+func main() {
+	TestList()
+	TestExtending()
+	TestRemove()
+	TestIssue4103()
+	TestIssue6349()
+	TestMove()
+	TestZeroList()
+	TestInsertBeforeUnknownMark()
+	TestInsertAfterUnknownMark()
+	TestTransform()
+}