add from giga-device, new branch added

StgSharp.Common/Collections/RandomAccessibleStack.cs

@@ -0,0 +1,185 @@
+//-----------------------------------------------------------------------
+//-----------------------------------------------------------------------
+//     file="RandomAccessibleStack.cs"
+//     Project: StgSharp
+//     AuthorGroup: Nitload Space
+//     Copyright (c) Nitload Space. All rights reserved.
+//     
+//     Permission is hereby granted, free of charge, to any person 
+//     obtaining a copy of this software and associated documentation 
+//     files (the “Software”), to deal in the Software without restriction, 
+//     including without limitation the rights to use, copy, modify, merge,
+//     publish, distribute, sublicense, and/or sell copies of the Software, 
+//     and to permit persons to whom the Software is furnished to do so, 
+//     subject to the following conditions:
+//     
+//     The above copyright notice and 
+//     this permission notice shall be included in all copies 
+//     or substantial portions of the Software.
+//     
+//     THE SOFTWARE IS PROVIDED “AS IS”, 
+//     WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, 
+//     INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
+//     FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. 
+//     IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, 
+//     DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, 
+//     ARISING FROM, OUT OF OR IN CONNECTION WITH 
+//     THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+//     
+//-----------------------------------------------------------------------
+//-----------------------------------------------------------------------
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+using System.Runtime.CompilerServices;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace StgSharp.Collections
+{
+    public class RandomAccessibleStack<T> : IEnumerable<T>
+    {
+
+        private const int DefaultCapacity = 4;
+
+        private T[] _array;
+        private int _size;
+        private int _version;
+
+        /// <summary>
+        ///   Initializes a new instance of the RandomAccessStack class that is empty and has the
+        ///   default initial capacity.
+        /// </summary>
+        public RandomAccessibleStack()
+        {
+            _array = new T[DefaultCapacity];
+        }
+
+        /// <summary>
+        ///   Initializes a new instance of the RandomAccessStack class that is empty and has the
+        ///   specified initial capacity.
+        /// </summary>
+        public RandomAccessibleStack( int capacity )
+        {
+            if( capacity < 0 ) {
+                throw new ArgumentOutOfRangeException(
+                    nameof( capacity ), "Capacity must be non-negative." );
+            }
+
+            _array = new T[capacity];
+        }
+
+        /// <summary>
+        ///   Gets or sets the element at the specified index in the stack (0 = bottom, Count-1 =
+        ///   top).
+        /// </summary>
+        public T this[ int index ]
+        {
+            get
+            {
+                if( index < 0 || index >= _size ) {
+                    throw new ArgumentOutOfRangeException( nameof( index ) );
+                }
+
+                return _array[ index ];
+            }
+            /*
+            set
+            {
+                if( index < 0 || index >= _size ) {
+                    throw new ArgumentOutOfRangeException( nameof( index ) );
+                }
+                _array[ index ] = value;
+                _version++;
+            }
+            /**/
+        }
+
+        /// <summary>
+        ///   Gets the number of elements contained in the stack.
+        /// </summary>
+        public int Count => _size;
+
+        /// <summary>
+        ///   Removes all objects from the stack.
+        /// </summary>
+        public void Clear()
+        {
+            Array.Clear( _array, 0, _size );
+            _size = 0;
+            _version++;
+        }
+
+        /// <summary>
+        ///   Returns an enumerator that iterates through the stack from top to bottom. Throws if
+        ///   the stack is modified during iteration.
+        /// </summary>
+        public IEnumerator<T> GetEnumerator()
+        {
+            int expectedVersion = _version;
+            for( int i = _size - 1; i >= 0; i-- )
+            {
+                if( expectedVersion != _version ) {
+                    throw new InvalidOperationException(
+                        "Collection was modified during enumeration." );
+                }
+
+                yield return _array[ i ];
+            }
+        }
+
+        /// <summary>
+        ///   Returns the object at the top of the stack without removing it.
+        /// </summary>
+        public T Peek()
+        {
+            if( _size == 0 ) {
+                throw new InvalidOperationException( "Stack is empty." );
+            }
+
+            return _array[ _size - 1 ];
+        }
+
+        /// <summary>
+        ///   Removes and returns the object at the top of the stack.
+        /// </summary>
+        public T Pop()
+        {
+            if( _size == 0 ) {
+                throw new InvalidOperationException( "Stack is empty." );
+            }
+
+            T item = _array[ --_size ];
+            _array[ _size ] = default!;
+            _version++;
+            return item;
+        }
+
+        /// <summary>
+        ///   Adds an item to the top of the stack.
+        /// </summary>
+        public void Push( T item )
+        {
+            if( _size == _array.Length ) {
+                EnsureCapacity( _size + 1 );
+            }
+
+            _array[ _size++ ] = item;
+            _version++;
+        }
+
+        private void EnsureCapacity( int min )
+        {
+            int newCapacity = _array.Length == 0 ? DefaultCapacity : _array.Length * 2;
+            if( newCapacity < min ) {
+                newCapacity = min;
+            }
+
+            Array.Resize( ref _array, newCapacity );
+        }
+
+        IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+
+    }
+}