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// ==++==
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// ==--==
/*=============================================================================
**
** Class: Stack
**
** <OWNER>Microsoft</OWNER>
**
** Purpose: An array implementation of a stack.
**
**
=============================================================================*/
namespace System.Collections {
using System;
using System.Security.Permissions;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.Diagnostics.Contracts;
// A simple stack of objects. Internally it is implemented as an array,
// so Push can be O(n). Pop is O(1).
[DebuggerTypeProxy(typeof(System.Collections.Stack.StackDebugView))]
[DebuggerDisplay("Count = {Count}")]
[System.Runtime.InteropServices.ComVisible(true)]
[Serializable]
public class Stack : ICollection, ICloneable {
private Object[] _array; // Storage for stack elements
[ContractPublicPropertyName("Count")]
private int _size; // Number of items in the stack.
private int _version; // Used to keep enumerator in sync w/ collection.
[NonSerialized]
private Object _syncRoot;
private const int _defaultCapacity = 10;
public Stack() {
_array = new Object[_defaultCapacity];
_size = 0;
_version = 0;
}
// Create a stack with a specific initial capacity. The initial capacity
// must be a non-negative number.
public Stack(int initialCapacity) {
if (initialCapacity < 0)
throw new ArgumentOutOfRangeException("initialCapacity", Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum"));
Contract.EndContractBlock();
if (initialCapacity < _defaultCapacity)
initialCapacity = _defaultCapacity; // Simplify doubling logic in Push.
_array = new Object[initialCapacity];
_size = 0;
_version = 0;
}
// Fills a Stack with the contents of a particular collection. The items are
// pushed onto the stack in the same order they are read by the enumerator.
//
public Stack(ICollection col) : this((col==null ? 32 : col.Count))
{
if (col==null)
throw new ArgumentNullException("col");
Contract.EndContractBlock();
IEnumerator en = col.GetEnumerator();
while(en.MoveNext())
Push(en.Current);
}
public virtual int Count {
get {
Contract.Ensures(Contract.Result<int>() >= 0);
return _size;
}
}
public virtual bool IsSynchronized {
get { return false; }
}
public virtual Object SyncRoot {
get {
if( _syncRoot == null) {
System.Threading.Interlocked.CompareExchange<Object>(ref _syncRoot, new Object(), null);
}
return _syncRoot;
}
}
// Removes all Objects from the Stack.
public virtual void Clear() {
Array.Clear(_array, 0, _size); // Don't need to doc this but we clear the elements so that the gc can reclaim the references.
_size = 0;
_version++;
}
public virtual Object Clone() {
Contract.Ensures(Contract.Result<Object>() != null);
Stack s = new Stack(_size);
s._size = _size;
Array.Copy(_array, 0, s._array, 0, _size);
s._version = _version;
return s;
}
public virtual bool Contains(Object obj) {
int count = _size;
while (count-- > 0) {
if (obj == null) {
if (_array[count] == null)
return true;
}
else if (_array[count] != null && _array[count].Equals(obj)) {
return true;
}
}
return false;
}
// Copies the stack into an array.
public virtual void CopyTo(Array array, int index) {
if (array==null)
throw new ArgumentNullException("array");
if (array.Rank != 1)
throw new ArgumentException(Environment.GetResourceString("Arg_RankMultiDimNotSupported"));
if (index < 0)
throw new ArgumentOutOfRangeException("index", Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum"));
if (array.Length - index < _size)
throw new ArgumentException(Environment.GetResourceString("Argument_InvalidOffLen"));
Contract.EndContractBlock();
int i = 0;
if (array is Object[]) {
Object[] objArray = (Object[]) array;
while(i < _size) {
objArray[i+index] = _array[_size-i-1];
i++;
}
}
else {
while(i < _size) {
array.SetValue(_array[_size-i-1], i+index);
i++;
}
}
}
// Returns an IEnumerator for this Stack.
public virtual IEnumerator GetEnumerator() {
Contract.Ensures(Contract.Result<IEnumerator>() != null);
return new StackEnumerator(this);
}
// Returns the top object on the stack without removing it. If the stack
// is empty, Peek throws an InvalidOperationException.
public virtual Object Peek() {
if (_size==0)
throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_EmptyStack"));
Contract.EndContractBlock();
return _array[_size-1];
}
// Pops an item from the top of the stack. If the stack is empty, Pop
// throws an InvalidOperationException.
public virtual Object Pop() {
if (_size == 0)
throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_EmptyStack"));
//Contract.Ensures(Count == Contract.OldValue(Count) - 1);
Contract.EndContractBlock();
_version++;
Object obj = _array[--_size];
_array[_size] = null; // Free memory quicker.
return obj;
}
// Pushes an item to the top of the stack.
//
public virtual void Push(Object obj) {
//Contract.Ensures(Count == Contract.OldValue(Count) + 1);
if (_size == _array.Length) {
Object[] newArray = new Object[2*_array.Length];
Array.Copy(_array, 0, newArray, 0, _size);
_array = newArray;
}
_array[_size++] = obj;
_version++;
}
// Returns a synchronized Stack.
//
[HostProtection(Synchronization=true)]
public static Stack Synchronized(Stack stack) {
if (stack==null)
throw new ArgumentNullException("stack");
Contract.Ensures(Contract.Result<Stack>() != null);
Contract.EndContractBlock();
return new SyncStack(stack);
}
// Copies the Stack to an array, in the same order Pop would return the items.
public virtual Object[] ToArray()
{
Contract.Ensures(Contract.Result<Object[]>() != null);
Object[] objArray = new Object[_size];
int i = 0;
while(i < _size) {
objArray[i] = _array[_size-i-1];
i++;
}
return objArray;
}
[Serializable]
private class SyncStack : Stack
{
private Stack _s;
private Object _root;
internal SyncStack(Stack stack) {
_s = stack;
_root = stack.SyncRoot;
}
public override bool IsSynchronized {
get { return true; }
}
public override Object SyncRoot {
get {
return _root;
}
}
public override int Count {
get {
lock (_root) {
return _s.Count;
}
}
}
public override bool Contains(Object obj) {
lock (_root) {
return _s.Contains(obj);
}
}
public override Object Clone()
{
lock (_root) {
return new SyncStack((Stack)_s.Clone());
}
}
public override void Clear() {
lock (_root) {
_s.Clear();
}
}
public override void CopyTo(Array array, int arrayIndex) {
lock (_root) {
_s.CopyTo(array, arrayIndex);
}
}
public override void Push(Object value) {
lock (_root) {
_s.Push(value);
}
}
[SuppressMessage("Microsoft.Contracts", "CC1055")] // Thread safety problems with precondition - can't express the precondition as of Dev10.
public override Object Pop() {
lock (_root) {
return _s.Pop();
}
}
public override IEnumerator GetEnumerator() {
lock (_root) {
return _s.GetEnumerator();
}
}
[SuppressMessage("Microsoft.Contracts", "CC1055")] // Thread safety problems with precondition - can't express the precondition as of Dev10.
public override Object Peek() {
lock (_root) {
return _s.Peek();
}
}
public override Object[] ToArray() {
lock (_root) {
return _s.ToArray();
}
}
}
[Serializable]
private class StackEnumerator : IEnumerator, ICloneable
{
private Stack _stack;
private int _index;
private int _version;
private Object currentElement;
internal StackEnumerator(Stack stack) {
_stack = stack;
_version = _stack._version;
_index = -2;
currentElement = null;
}
public Object Clone()
{
return MemberwiseClone();
}
public virtual bool MoveNext() {
bool retval;
if (_version != _stack._version) throw new InvalidOperationException(Environment.GetResourceString(ResId.InvalidOperation_EnumFailedVersion));
if (_index == -2) { // First call to enumerator.
_index = _stack._size-1;
retval = ( _index >= 0);
if (retval)
currentElement = _stack._array[_index];
return retval;
}
if (_index == -1) { // End of enumeration.
return false;
}
retval = (--_index >= 0);
if (retval)
currentElement = _stack._array[_index];
else
currentElement = null;
return retval;
}
public virtual Object Current {
get {
if (_index == -2) throw new InvalidOperationException(Environment.GetResourceString(ResId.InvalidOperation_EnumNotStarted));
if (_index == -1) throw new InvalidOperationException(Environment.GetResourceString(ResId.InvalidOperation_EnumEnded));
return currentElement;
}
}
public virtual void Reset() {
if (_version != _stack._version) throw new InvalidOperationException(Environment.GetResourceString(ResId.InvalidOperation_EnumFailedVersion));
_index = -2;
currentElement = null;
}
}
internal class StackDebugView {
private Stack stack;
public StackDebugView( Stack stack) {
if( stack == null)
throw new ArgumentNullException("stack");
Contract.EndContractBlock();
this.stack = stack;
}
[DebuggerBrowsable(DebuggerBrowsableState.RootHidden)]
public Object[] Items {
get {
return stack.ToArray();
}
}
}
}
}
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