1 files changed, 129 insertions, 0 deletions
diff --git a/runtime/CSharp2/Sources/Antlr3.Runtime/Antlr.Runtime.Misc/FastQueue.cs b/runtime/CSharp2/Sources/Antlr3.Runtime/Antlr.Runtime.Misc/FastQueue.cs
new file mode 100644
index 0000000..9d3cf65
--- /dev/null
+++ b/runtime/CSharp2/Sources/Antlr3.Runtime/Antlr.Runtime.Misc/FastQueue.cs
@@ -0,0 +1,129 @@
+/*
+ * [The "BSD licence"]
+ * Copyright (c) 2005-2008 Terence Parr
+ * All rights reserved.
+ *
+ * Conversion to C#:
+ * Copyright (c) 2008-2009 Sam Harwell, Pixel Mine, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+namespace Antlr.Runtime.Misc {
+    using System.Collections.Generic;
+    using ArgumentException = System.ArgumentException;
+    using InvalidOperationException = System.InvalidOperationException;
+
+    /** A queue that can dequeue and get(i) in O(1) and grow arbitrarily large.
+     *  A linked list is fast at dequeue but slow at get(i).  An array is
+     *  the reverse.  This is O(1) for both operations.
+     *
+     *  List grows until you dequeue last element at end of buffer. Then
+     *  it resets to start filling at 0 again.  If adds/removes are balanced, the
+     *  buffer will not grow too large.
+     *
+     *  No iterator stuff as that's not how we'll use it.
+     */
+    public class FastQueue<T> {
+        /** <summary>dynamically-sized buffer of elements</summary> */
+        internal List<T> _data = new List<T>();
+        /** <summary>index of next element to fill</summary> */
+        internal int _p = 0;
+
+        public virtual int Count {
+            get {
+                return _data.Count - _p;
+            }
+        }
+
+        /// <summary>
+        /// How deep have we gone?
+        /// </summary>
+        public virtual int Range {
+            get;
+            protected set;
+        }
+
+        /** <summary>
+         *  Return element i elements ahead of current element.  i==0 gets
+         *  current element.  This is not an absolute index into the data list
+         *  since p defines the start of the real list.
+         *  </summary>
+         */
+        public virtual T this[int i] {
+            get {
+                int absIndex = _p + i;
+                if (absIndex >= _data.Count)
+                    throw new ArgumentException(string.Format("queue index {0} > last index {1}", absIndex, _data.Count - 1));
+                if (absIndex < 0)
+                    throw new ArgumentException(string.Format("queue index {0} < 0", absIndex));
+
+                if (absIndex > Range)
+                    Range = absIndex;
+
+                return _data[absIndex];
+            }
+        }
+
+        /** <summary>Get and remove first element in queue</summary> */
+        public virtual T Dequeue() {
+            if (Count == 0)
+                throw new InvalidOperationException();
+
+            T o = this[0];
+            _p++;
+            // have we hit end of buffer?
+            if (_p == _data.Count) {
+                // if so, it's an opportunity to start filling at index 0 again
+                Clear(); // size goes to 0, but retains memory
+            }
+            return o;
+        }
+
+        public virtual void Enqueue(T o) {
+            _data.Add(o);
+        }
+
+        public virtual T Peek() {
+            return this[0];
+        }
+
+        public virtual void Clear() {
+            _p = 0;
+            _data.Clear();
+        }
+
+        /** <summary>Return string of current buffer contents; non-destructive</summary> */
+        public override string ToString() {
+            System.Text.StringBuilder buf = new System.Text.StringBuilder();
+            int n = Count;
+            for (int i = 0; i < n; i++) {
+                buf.Append(this[i]);
+                if ((i + 1) < n)
+                    buf.Append(" ");
+            }
+            return buf.ToString();
+        }
+    }
+}