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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163 Stack stack = new Stack (contents);
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164 stack.current = current;
168 public virtual bool Contains(object obj) {
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172 for (int i = 0; i < count; i++) {
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173 if (contents[i].Equals(obj))
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180 public virtual void CopyTo (Array array, int index) {
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181 if (array == null) {
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182 throw new ArgumentNullException();
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186 throw new ArgumentOutOfRangeException();
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189 if (array.Rank > 1 ||
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190 index >= array.Length ||
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191 count > array.Length - index) {
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192 throw new ArgumentException();
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195 for (int i = current; i != -1; i--) {
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196 array.SetValue(contents[i],
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197 count - (i + 1) + index);
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201 private class Enumerator : IEnumerator {
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204 private int modCount;
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205 private int current;
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207 internal Enumerator(Stack s) {
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208 // this is odd. it seems that you need to
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209 // start one further ahead than current, since
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210 // MoveNext() gets called first when using an
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213 modCount = s.modCount;
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214 current = s.current + 1;
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217 public virtual object Current {
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219 if (modCount != stack.modCount
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221 || current > stack.count)
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222 throw new InvalidOperationException();
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223 return stack.contents[current];
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227 public virtual bool MoveNext() {
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228 if (modCount != stack.modCount
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229 || current == -1) {
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230 throw new InvalidOperationException();
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235 if (current == -1) {
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242 public virtual void Reset() {
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243 if (modCount != stack.modCount) {
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244 throw new InvalidOperationException();
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247 // start one ahead of stack.current, so the
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248 // first MoveNext() will put us at the top
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249 current = stack.current + 1;
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253 public virtual IEnumerator GetEnumerator() {
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254 return new Enumerator(this);
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257 public virtual object Peek() {
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258 if (current == -1) {
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259 throw new InvalidOperationException();
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261 return contents[current];
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265 public virtual object Pop() {
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266 if (current == -1) {
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267 throw new InvalidOperationException();
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271 object ret = contents[current];
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272 contents [current] = null;
277 // if we're down to capacity/4, go back to a
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278 // lower array size. this should keep us from
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279 // sucking down huge amounts of memory when
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280 // putting large numbers of items in the Stack.
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281 // if we're lower than 16, don't bother, since
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282 // it will be more trouble than it's worth.
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283 if (count <= (capacity/4) && count > 16) {
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284 Resize(capacity/2);
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291 public virtual void Push(Object o) {
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294 if (capacity == count) {
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295 Resize(capacity * 2);
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301 contents[current] = o;
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304 public virtual object[] ToArray() {
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305 object[] ret = new object[count];
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307 Array.Copy(contents, ret, count);
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309 // ret needs to be in LIFO order
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310 Array.Reverse(ret);
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