Introduce TargetString to eliminate text GC.

2022-11-21 14:09:01 +08:00
parent 784c3fc338
commit 109b489104
4 changed files with 154 additions and 10 deletions
--- a/Assets/Cryville/Common/Buffers/TargetString.cs
+++ b/Assets/Cryville/Common/Buffers/TargetString.cs
@@ -0,0 +1,120 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+
+namespace Cryville.Common.Buffers {
+	/// <summary>
+	/// An auto-resized <see cref="char" /> array as a variable-length string used as a target that is modified frequently.
+	/// </summary>
+	public class TargetString : IEnumerable<char> {
+		public event Action OnUpdate;
+		char[] _arr;
+		bool _invalidated;
+		/// <summary>
+		/// Creates an instance of the <see cref="TargetString" /> class with a capacity of 16.
+		/// </summary>
+		public TargetString() : this(16) { }
+		/// <summary>
+		/// Creates an instance of the <see cref="TargetString" /> class.
+		/// </summary>
+		/// <param name="capacity">The initial capacity of the string.</param>
+		public TargetString(int capacity) {
+			_arr = new char[capacity];
+		}
+		/// <summary>
+		/// Gets or sets one of the characters in the string.
+		/// </summary>
+		/// <param name="index">The zero-based index of the character.</param>
+		/// <returns>The character at the given index.</returns>
+		/// <exception cref="ArgumentOutOfRangeException"><paramref name="index" /> is less than 0 or not less than <see cref="Length" />.</exception>
+		/// <remarks>
+		/// <para>Set <see cref="Length" /> to a desired value before updating the characters.</para>
+		/// <para>Call <see cref=" Validate" /> after all the characters are updated.</para>
+		/// </remarks>
+		public char this[int index] {
+			get {
+				if (index < 0 || index >= m_length)
+					throw new ArgumentOutOfRangeException("index");
+				return _arr[index];
+			}
+			set {
+				if (index < 0 || index >= m_length)
+					throw new ArgumentOutOfRangeException("index");
+				if (_arr[index] == value) return;
+				_arr[index] = value;
+				_invalidated = true;
+			}
+		}
+		int m_length;
+		/// <summary>
+		/// The length of the string.
+		/// </summary>
+		public int Length {
+			get {
+				return m_length;
+			}
+			set {
+				if (m_length == value) return;
+				if (_arr.Length < value) {
+					var len = m_length;
+					while (len < value) len *= 2;
+					var arr2 = new char[len];
+					Array.Copy(_arr, arr2, m_length);
+					_arr = arr2;
+				}
+				m_length = value;
+				_invalidated = true;
+			}
+		}
+		/// <summary>
+		/// Validates the string.
+		/// </summary>
+		public void Validate() {
+			if (!_invalidated) return;
+			_invalidated = false;
+			var ev = OnUpdate;
+			if (ev != null) OnUpdate.Invoke();
+		}
+
+		IEnumerator IEnumerable.GetEnumerator() {
+			return GetEnumerator();
+		}
+		public IEnumerator<char> GetEnumerator() {
+			return new Enumerator(this);
+		}
+
+		class Enumerator : IEnumerator<char> {
+			TargetString _self;
+			int _index = -1;
+			public Enumerator(TargetString self) { _self = self; }
+
+			public char Current {
+				get {
+					if (_index < 0)
+						throw new InvalidOperationException(_index == -1 ? "Enum not started" : "Enum ended");
+					return _self[_index];
+				}
+			}
+
+			object IEnumerator.Current { get { return Current; } }
+
+			public void Dispose() {
+				_index = -2;
+			}
+
+			public bool MoveNext() {
+				if (_index == -2) return false;
+				_index++;
+				if (_index >= _self.Length) {
+					_index = -2;
+					return false;
+				}
+				return true;
+			}
+
+			public void Reset() {
+				_index = -1;
+			}
+		}
+	}
+}