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Diffstat (limited to 'test/typeparam/listimp2.dir/a.go')
-rw-r--r-- | test/typeparam/listimp2.dir/a.go | 298 |
1 files changed, 298 insertions, 0 deletions
diff --git a/test/typeparam/listimp2.dir/a.go b/test/typeparam/listimp2.dir/a.go new file mode 100644 index 0000000..3a7dfc3 --- /dev/null +++ b/test/typeparam/listimp2.dir/a.go @@ -0,0 +1,298 @@ +// 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 a + +import ( + "fmt" +) + +// 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)) + } + } +} |