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//
// assembly: System
// namespace: System.Text.RegularExpressions
// file: cache.cs
//
// author: Dan Lewis (dlewis@gmx.co.uk)
// (c) 2002
using System;
using System.Collections;
namespace System.Text.RegularExpressions {
class FactoryCache {
public FactoryCache (int capacity) {
this.capacity = capacity;
this.factories = new Hashtable (capacity);
this.mru_list = new MRUList ();
}
public void Add (string pattern, RegexOptions options, IMachineFactory factory) {
lock (this) {
Key k = new Key (pattern, options);
while (factories.Count >= capacity) {
object victim = mru_list.Evict ();
if (victim != null)
factories.Remove ((Key)victim);
}
factories[k] = factory;
mru_list.Use (k);
}
}
public IMachineFactory Lookup (string pattern, RegexOptions options) {
lock (this) {
Key k = new Key (pattern, options);
if (factories.Contains (k)) {
mru_list.Use (k);
return (IMachineFactory)factories[k];
}
}
return null;
}
private int capacity;
private Hashtable factories;
private MRUList mru_list;
class Key {
public string pattern;
public RegexOptions options;
public Key (string pattern, RegexOptions options) {
this.pattern = pattern;
this.options = options;
}
public override int GetHashCode () {
return pattern.GetHashCode () ^ (int)options;
}
public override bool Equals (object o) {
if (o == null || !(o is Key))
return false;
Key k = (Key)o;
return options == k.options && pattern.Equals (k.pattern);
}
public override string ToString () {
return "('" + pattern + "', [" + options + "])";
}
}
}
class MRUList {
public MRUList () {
head = tail = null;
}
public void Use (object o) {
Node node;
if (head == null) {
node = new Node (o);
head = tail = node;
return;
}
node = head;
while (node != null && !o.Equals (node.value))
node = node.previous;
if (node == null)
node = new Node (o);
else {
if (node == head)
return;
if (node == tail)
tail = node.next;
else
node.previous.next = node.next;
node.next.previous = node.previous;
}
head.next = node;
node.previous = head;
node.next = null;
head = node;
}
public object Evict () {
if (tail == null)
return null;
object o = tail.value;
tail = tail.next;
if (tail == null)
head = null;
else
tail.previous = null;
return o;
}
private Node head, tail;
private class Node {
public object value;
public Node previous, next;
public Node (object value) {
this.value = value;
}
}
}
}
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