//
// assembly: System
// namespace: System.Text.RegularExpressions
// file: cache.cs
//
// author: Dan Lewis (dlewis@gmx.co.uk)
// (c) 2002
//
// 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;
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);
Cleanup ();
factories[k] = factory;
mru_list.Use (k);
}
}
// lock must be held by the caller
void Cleanup ()
{
while (factories.Count >= capacity && capacity > 0) {
object victim = mru_list.Evict ();
if (victim != null)
factories.Remove ((Key) victim);
}
}
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;
}
public int Capacity {
get { return capacity; }
set {
// < 0 check done in the caller (Regex.CacheSize)
lock (this) {
capacity = value;
Cleanup ();
}
}
}
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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