feat(Go-StudyExample):

2020/12/31:添加container包使用示例和源码分析 2020/12/31:添加validator.v8源码解析和使用示例
2020-12-31 16:48:30 +08:00
parent 6d079549f1
commit 9c93a35685
22 changed files with 5167 additions and 0 deletions
@@ -0,0 +1,157 @@
+// Copyright 2009 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 heap provides heap operations for any type that implements
+// heap.Interface. A heap is a tree with the property that each node is the
+// minimum-valued node in its subtree.
+//
+// The minimum element in the tree is the root, at index 0.
+//
+// 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_pq_test.go has the complete source.
+//
+//read note 拷贝一个代码过来解析.感觉在go里面拷贝代码简单多了，依赖可以直接使用。我在这边使用read note(自定义todo标识)来标识我的解析.
+package sourceAnalysis
+
+import "sort"
+
+// The Interface type describes the requirements
+// for a type using the routines in this package.
+// Any type that implements it may be used as a
+// min-heap with the following invariants (established after
+// Init has been called or if the data is empty or sorted):
+//
+//	!h.Less(j, i) for 0 <= i < h.Len() and 2*i+1 <= j <= 2*i+2 and j < h.Len()
+//
+// Note that Push and Pop in this interface are for package heap's
+// implementation to call. To add and remove things from the heap,
+// use heap.Push and heap.Pop.
+type Interface interface {
+	sort.Interface
+	Push(x interface{}) // add x as element Len()
+	Pop() interface{}   // remove and return element Len() - 1.
+}
+
+// Init establishes the heap invariants required by the other routines in this package.
+// Init is idempotent with respect to the heap invariants
+// and may be called whenever the heap invariants may have been invalidated.
+// The complexity is O(n) where n = h.Len().
+//read note 对整个Interface 进行重构，时间复杂度是 O(n)
+func Init(h Interface) {
+	// heapify
+	n := h.Len()
+	//read note 从最小父节点，到第0位的根节点，分别向下进行重构处理(之所以要用循环是因为一次向下的重构，只能对一条连续的分支进行重构，不彻底.)
+	for i := n/2 - 1; i >= 0; i-- {
+		down(h, i, n)
+	}
+}
+
+// Push pushes the element x onto the heap.
+// The complexity is O(log n) where n = h.Len().
+// read note 这个Push方法是往 Interface里面去新增一个元素.和我们继承的Push方法有差别.这边同时候做了重构操作.
+//  一次Push的时间复杂度是 O(logN),一次Init的时间复杂度是O(N),按道理Push的元素越多，Init的效率越高
+func Push(h Interface, x interface{}) {
+	//read note 先把元素添加进去
+	h.Push(x)
+	//read note 然后在从下往上进行重构处理，正常情况下Push都是把元素添加在最后一个位置，如果实现的方法，把Push添加到其他位置如果不进行Init，应该是会有问题.
+	up(h, h.Len()-1)
+}
+
+// Pop removes and returns the minimum element (according to Less) from the heap.
+// The complexity is O(log n) where n = h.Len().
+// Pop is equivalent to Remove(h, 0).
+//read note 把最小的元素输出，需要注意的是真正的Pop必须是调用这个方法，而不是我们继承的那个方法.
+// 时间复杂度是O(logN)
+func Pop(h Interface) interface{} {
+	//read note 真正的Pop输出的是最小的元素，也就是最小堆的第0位置的元素
+	// 所以这边的操作是把第0位的数组放到最后一位，然后从位置0开始，到N-1的位置，对所有元素进行down(父子节点比较交换)的操作
+	n := h.Len() - 1
+	h.Swap(0, n)
+	down(h, 0, n)
+	return h.Pop()
+}
+
+// Remove removes and returns the element at index i from the heap.
+// The complexity is O(log n) where n = h.Len().
+//read note 移除某个位置的元素，时间复杂度是 o(logn)
+func Remove(h Interface, i int) interface{} {
+	//read note 判断移除的下标不等于最后一个元素位置，要特殊处理
+	n := h.Len() - 1
+	if n != i {
+		//read note 交换第i个元素和最后一个元素
+		h.Swap(i, n)
+		//read note Fix的处理操作，这边只会处理到移除一个元素后的位置，也就是说被移除的那个元素(在最后的位置)不会参与重构数组的操作
+		if !down(h, i, n) {
+			up(h, i)
+		}
+	}
+	//read note 调用Pop，把最后一个元素返回回去
+	return h.Pop()
+}
+
+// Fix re-establishes the heap ordering after the element at index i has changed its value.
+// Changing the value of the element at index i and then calling Fix is equivalent to,
+// but less expensive than, calling Remove(h, i) followed by a Push of the new value.
+// The complexity is O(log n) where n = h.Len().
+//read note 当下标为i的元素发生改变，需要进行一次Fix的处理,时间复杂度是 o(logn)
+func Fix(h Interface, i int) {
+	//read note 想从下标i的这个元素往下查找处理，如果往下没有交换元素，再往上进行处理.
+	if !down(h, i, h.Len()) {
+		up(h, i)
+	}
+}
+
+//read note  h:  对应的数组数据
+//read note  j:子节点的下标
+//read note  方法作用
+func up(h Interface, j int) {
+	for {
+		//read note 拿到对应的父节点的下标
+		i := (j - 1) / 2 // parent
+		//read note 找到最后一个父节点 || 父节点比子节点小，则跳出循环
+		if i == j || !h.Less(j, i) {
+			break
+		}
+		//read note 否则就是父节点比子节点的值大，需要交换对应的元素，然后找到父节点的下标，再往上找其父节点的关系
+		h.Swap(i, j)
+		j = i
+	}
+}
+
+//read note  h:  对应的数组数据
+//read note  i0: 需要下发处理的坐标，这边也就是左右子节点的父节点下标.
+//read note  n:  数组对应的总长度
+//read note  方法作用：从父节点开始，循环向下判断对应的元素是否在对应的环境上
+func down(h Interface, i0, n int) bool {
+	//read note 把父节点的下标拿出来
+	i := i0
+
+	//read note 循环的结束条件是：
+	for {
+		//read note 找到左边子节点下标
+		j1 := 2*i + 1
+		//read note 退出条件1：超过最大长度或者是负值(这个应该是针对传入就有问题的处理)
+		if j1 >= n || j1 < 0 { // j1 < 0 after int overflow
+			break
+		}
+		//read note 拿到左孩子和右孩子中比较小的那个元素（的下标）
+		j := j1 // left child
+		if j2 := j1 + 1; j2 < n && h.Less(j2, j1) {
+			j = j2 // = 2*i + 2  // right child
+		}
+
+		//read note 判断父节点和子节点的大小关系，小的元素应该在父节点，所以如果子节点本身就比较小，直接退出循环，否则交换元素
+		//read note 然后再把下标移动到被交换的这个元素上，计算被交换的这个元素和它的左右子节点的大小关系，进入下一个循环
+		if !h.Less(j, i) {
+			break
+		}
+		h.Swap(i, j)
+		i = j
+	}
+	//read note 判断是否发生了交换操作
+	return i > i0
+}
@@ -0,0 +1,255 @@
+// Copyright 2009 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 implements a doubly linked list.
+//
+// To iterate over a list (where l is a *List):
+//	for e := l.Front(); e != nil; e = e.Next() {
+//		// do something with e.Value
+//	}
+//
+package sourceAnalysis
+
+// Element is an element of a linked list.
+//read note list中对应的元素,list相当是通过一个链表来链接所有的Element元素.
+type Element 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()).
+	//read note 指向下一个和前一个元素的指针.internally a list l is implemented as a ring:内部实现实际是一个环
+	next, prev *Element
+
+	// The list to which this element belongs.
+	//read note 链表头，这边是设置表头为哨兵的模式进行链表的处理的
+	list *List
+
+	// The value stored with this element.
+	//read note Element中实际的元素值
+	Value interface{}
+}
+
+// Next returns the next list element or nil.
+func (e *Element) Next() *Element {
+	//read note 获取下一个元素，这边判断条件包含 list不为空，以及next不为链表头结点（哨兵）.
+	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) Prev() *Element {
+	//read note 与Next一样的道理，判断list不为空，以及pre不等于链表头结点
+	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.
+//read note 设置哨兵的链表实现
+type List struct {
+	//read note 哨兵结点
+	root Element // sentinel list element, only &root, root.prev, and root.next are used
+	//read note 链表长度
+	len int // current list length excluding (this) sentinel element
+}
+
+// Init initializes or clears list l.
+func (l *List) Init() *List {
+	//read note 初始化的时候，链表的哨兵结点pre和next是互相指向的，这也可以作为判断链表是否为空的依据
+	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).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.
+// read note 返回第一个元素，如果链表不为空，则返回哨兵结点的next就是一个链表结点
+func (l *List) Front() *Element {
+	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.
+// read note 所以list是一个环，如果链表不为空，则最后一个元素可以通过哨兵的prev来获取到.
+func (l *List) Back() *Element {
+	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.
+//read note 在某一个位置后面加入一个element,只需要设置一下长度，前后链表地址的指向即可。
+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
+}
+
+// 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.
+//read note 移除某个元素，返回该元素并设置不相关的属性为空，防止内存泄露.
+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
+}
+
+// move moves e to next to at and returns e.
+//read note 移动某个元素，本质上和插入某个元素有点类似.即移除对应节点后，再在对应的节点后面插入该元素
+func (l *List) move(e, at *Element) *Element {
+	if e == at {
+		return e
+	}
+	e.prev.next = e.next
+	e.next.prev = e.prev
+
+	n := at.next
+	at.next = e
+	e.prev = at
+	e.next = n
+	n.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) 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)
+	}
+	return e.Value
+}
+
+// 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 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 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) InsertBefore(v interface{}, mark *Element) *Element {
+	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) InsertAfter(v interface{}, mark *Element) *Element {
+	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) MoveToFront(e *Element) {
+	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) MoveToBack(e *Element) {
+	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) MoveBefore(e, mark *Element) {
+	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) MoveAfter(e, mark *Element) {
+	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) 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 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) 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)
+	}
+}
@@ -0,0 +1,150 @@
+// Copyright 2009 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 ring implements operations on circular lists.
+package sourceAnalysis
+
+// A Ring is an element of a circular list, or ring.
+// Rings do not have a beginning or end; a pointer to any ring element
+// serves as reference to the entire ring. Empty rings are represented
+// as nil Ring pointers. The zero value for a Ring is a one-element
+// ring with a nil Value.
+//
+//read note 环结构:指针可能指向任意元素,空链表只有一个nil元素
+type Ring struct {
+	next, prev *Ring
+	Value      interface{} // for use by client; untouched by this library
+}
+
+//read note 初始化只是做了指针指向，不会增加环的值
+func (r *Ring) init() *Ring {
+	r.next = r
+	r.prev = r
+	return r
+}
+
+// Next returns the next ring element. r must not be empty.
+//read note：环的下一个值,如果环的next为空，则初始化该环
+func (r *Ring) Next() *Ring {
+	if r.next == nil {
+		return r.init()
+	}
+	return r.next
+}
+
+// Prev returns the previous ring element. r must not be empty.
+func (r *Ring) Prev() *Ring {
+	if r.next == nil {
+		return r.init()
+	}
+	return r.prev
+}
+
+// Move moves n % r.Len() elements backward (n < 0) or forward (n >= 0)
+// in the ring and returns that ring element. r must not be empty.
+//
+//read note 对环上的当前元素进行n次位置的移动，小于0则向后移动，大于0则向前移动
+func (r *Ring) Move(n int) *Ring {
+	if r.next == nil {
+		return r.init()
+	}
+	switch {
+	case n < 0:
+		for ; n < 0; n++ {
+			r = r.prev
+		}
+	case n > 0:
+		for ; n > 0; n-- {
+			r = r.next
+		}
+	}
+	return r
+}
+
+// New creates a ring of n elements.
+//read note 创建n个节点的环
+func New1(n int) *Ring {
+	if n <= 0 {
+		return nil
+	}
+	r := new(Ring)
+	p := r
+	for i := 1; i < n; i++ {
+		p.next = &Ring{prev: p}
+		p = p.next
+	}
+	p.next = r
+	r.prev = p
+	return r
+}
+
+// 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.
+//
+// If r and s point to the same ring, linking
+// them removes the elements between r and s from the ring.
+// The removed elements form a subring and the result is a
+// reference to that subring (if no elements were removed,
+// the result is still the original value for r.Next(),
+// and not nil).
+//
+// If r and s point to different rings, linking
+// them creates a single ring with the elements of s inserted
+// after r. The result points to the element following the
+// last element of s after insertion.
+//
+//read note 链接环，如果是两个相同的环则环不改变，链接完环会少掉原来的第一个元素....(神奇)
+// 如果是两个不同的环，则把另一个环接到上一个环的后面，链接完的第一个元素是原来环的next的元素.第二个元素
+func (r *Ring) Link(s *Ring) *Ring {
+	n := r.Next()
+	if s != nil {
+		p := s.Prev()
+		// Note: Cannot use multiple assignment because
+		// evaluation order of LHS is not specified.
+		r.next = s
+		s.prev = r
+		n.prev = p
+		p.next = n
+	}
+	return n
+}
+
+// Unlink removes n % r.Len() elements from the ring r, starting
+// at r.Next(). If n % r.Len() == 0, r remains unchanged.
+// The result is the removed subring. r must not be empty.
+//
+//read note 断开环上n个元素，这里会根据n%r.Len 得到的余数进行Unlink,因为环是没有起点终点的，所以超过或者不超过环的长度都是按照余数进行处理
+func (r *Ring) Unlink(n int) *Ring {
+	if n <= 0 {
+		return nil
+	}
+	return r.Link(r.Move(n + 1))
+}
+
+// Len computes the number of elements in ring r.
+// It executes in time proportional to the number of elements.
+//
+func (r *Ring) Len() int {
+	n := 0
+	if r != nil {
+		n = 1
+		for p := r.Next(); p != r; p = p.next {
+			n++
+		}
+	}
+	return n
+}
+
+// Do calls function f on each element of the ring, in forward order.
+// The behavior of Do is undefined if f changes *r.
+//read note 对环上的所有元素进行函数操作,但是这边的操作好像是没办法改变环中的元素的,只能进行提取或者输出
+func (r *Ring) Do(f func(interface{})) {
+	if r != nil {
+		f(r.Value)
+		for p := r.Next(); p != r; p = p.next {
+			f(p.Value)
+		}
+	}
+}