using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace BSF.BaseService.NScript.Core
{
 /// <summary>
 /// 字符串解析器
 /// 缓存解析结果,加快下次解析
 /// </summary>
 public class StringParser<T>
 {
 private Dictionary<string, T> cache = new Dictionary<string, T>();
 private readonly int recoverCount = 5000;//随机回收限制,未来替换为高性能的LRU

 public void ClearCache()
 {
 lock (this)
 {
 cache.Clear();
 }
 }

 public T Parser(string key, Func<T> func)
 {
 if (cache.ContainsKey(key))
 {
 return cache[key];
 }
 else
 {
 lock (this)
 {
 if (!cache.ContainsKey(key))
 {
 //随机回收一半
 if (cache.Count > recoverCount)
 {
 List<string> recoverKeys = new List<string>(cache.Keys);
 for (int i = 0; i < recoverCount / 2; i++)
 {
 int keyIndex = new Random(new Guid().GetHashCode()).Next(recoverKeys.Count);
 cache.Remove(recoverKeys[keyIndex]);
 recoverKeys.RemoveAt(keyIndex);
 }
 }

 T t = func.Invoke();
 cache.Add(key, t);
 }
 return cache[key];
 }
 }
 }
 }
}