2 // System.Collections.Stack
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5 // Garrett Rooney (rooneg@electricjellyfish.net)
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7 // (C) 2001 Garrett Rooney
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10 namespace System.Collections {
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13 public class Stack : ICollection, IEnumerable, ICloneable {
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16 private object[] contents;
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17 private int current = -1;
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18 private int count = 0;
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19 private int capacity = 16;
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20 private int modCount = 0;
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22 private void Resize(int ncapacity) {
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23 object[] ncontents = new object[ncapacity];
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25 Array.Copy(contents, ncontents, count);
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27 capacity = ncapacity;
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28 contents = ncontents;
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32 contents = new object[capacity];
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35 public Stack(ICollection collection) {
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36 capacity = collection.Count;
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37 contents = new object[capacity];
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38 current = capacity - 1;
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41 collection.CopyTo(contents, 0);
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44 public Stack(int c) {
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46 contents = new object[capacity];
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50 private class SyncStack : Stack {
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54 internal SyncStack(Stack s) {
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58 public override int Count {
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61 return stack.Count;
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67 public override bool IsReadOnly {
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70 return stack.IsReadOnly;
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76 public override bool IsSynchronized {
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77 get { return true; }
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80 public override object SyncRoot {
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81 get { return stack.SyncRoot; }
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84 public override void Clear() {
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85 lock(stack) { stack.Clear(); }
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88 public override object Clone() {
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90 return Stack.Synchronized((Stack)stack.Clone());
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94 public override bool Contains(object obj) {
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95 lock (stack) { return stack.Contains(obj); }
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98 public override void CopyTo(Array array, int index) {
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99 lock (stack) { stack.CopyTo(array, index); }
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102 public override IEnumerator GetEnumerator() {
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104 return new Enumerator(stack);
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108 public override object Peek() {
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109 lock (stack) { return stack.Peek(); }
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112 public override object Pop() {
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113 lock (stack) { return stack.Pop(); }
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116 public override void Push(object obj) {
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117 lock (stack) { stack.Push(obj); }
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120 public override object[] ToArray() {
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121 lock (stack) { return stack.ToArray(); }
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125 public static Stack Synchronized(Stack s) {
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127 throw new ArgumentNullException();
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130 return new SyncStack(s);
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133 public virtual int Count {
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134 get { return count; }
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138 public virtual bool IsReadOnly {
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139 get { return false; }
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143 public virtual bool IsSynchronized {
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144 get { return false; }
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147 public virtual object SyncRoot {
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148 get { return this; }
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151 public virtual void Clear() {
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154 for (int i = 0; i < count; i++) {
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155 contents[i] = null;
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162 public virtual object Clone() {
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165 stack = new Stack();
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167 stack.current = current;
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168 stack.contents = contents;
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169 stack.count = count;
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170 stack.capacity = capacity;
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175 public virtual bool Contains(object obj) {
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179 for (int i = 0; i < count; i++) {
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180 if (contents[i].Equals(obj))
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187 public virtual void CopyTo (Array array, int index) {
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188 if (array == null) {
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189 throw new ArgumentNullException();
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193 throw new ArgumentOutOfRangeException();
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196 if (array.Rank > 1 ||
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197 index >= array.Length ||
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198 count > array.Length - index) {
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199 throw new ArgumentException();
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202 for (int i = current; i != -1; i--) {
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203 array.SetValue(contents[i],
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204 count - (i + 1) + index);
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208 private class Enumerator : IEnumerator {
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211 private int modCount;
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212 private int current;
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214 internal Enumerator(Stack s) {
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215 // this is odd. it seems that you need to
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216 // start one further ahead than current, since
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217 // MoveNext() gets called first when using an
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220 modCount = s.modCount;
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221 current = s.current + 1;
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224 public virtual object Current {
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226 if (modCount != stack.modCount
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228 || current > stack.count)
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229 throw new InvalidOperationException();
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230 return stack.contents[current];
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234 public virtual bool MoveNext() {
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235 if (modCount != stack.modCount
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236 || current == -1) {
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237 throw new InvalidOperationException();
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242 if (current == -1) {
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249 public virtual void Reset() {
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250 if (modCount != stack.modCount) {
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251 throw new InvalidOperationException();
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254 // start one ahead of stack.current, so the
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255 // first MoveNext() will put us at the top
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256 current = stack.current + 1;
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260 public virtual IEnumerator GetEnumerator() {
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261 return new Enumerator(this);
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264 public virtual object Peek() {
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265 if (current == -1) {
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266 throw new InvalidOperationException();
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268 return contents[current];
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272 public virtual object Pop() {
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273 if (current == -1) {
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274 throw new InvalidOperationException();
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278 object ret = contents[current];
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283 // if we're down to capacity/4, go back to a
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284 // lower array size. this should keep us from
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285 // sucking down huge amounts of memory when
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286 // putting large numbers of items in the Stack.
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287 // if we're lower than 16, don't bother, since
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288 // it will be more trouble than it's worth.
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289 if (count <= (capacity/4) && count > 16) {
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290 Resize(capacity/2);
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297 public virtual void Push(Object o) {
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300 if (capacity == count) {
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301 Resize(capacity * 2);
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307 contents[current] = o;
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310 public virtual object[] ToArray() {
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311 object[] ret = new object[count];
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313 Array.Copy(contents, ret, count);
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315 // ret needs to be in LIFO order
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316 Array.Reverse(ret);
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