From d2ccc3159f029fa1f1618cb64c5b86be259487c2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timo=20Westk=C3=A4mper?= <timo.westkamper@mysema.com>
Date: Wed, 7 Jan 2009 13:27:25 +0000
Subject: [PATCH] added reflection based FactoryMap implementation

---
 .../com/mysema/query/util/FactoryMap.java     | 57 +++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100644 querydsl-core/src/main/java/com/mysema/query/util/FactoryMap.java

diff --git a/querydsl-core/src/main/java/com/mysema/query/util/FactoryMap.java b/querydsl-core/src/main/java/com/mysema/query/util/FactoryMap.java
new file mode 100644
index 000000000..9a684282d
--- /dev/null
+++ b/querydsl-core/src/main/java/com/mysema/query/util/FactoryMap.java
@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2006 Mysema Ltd.
+ * All rights reserved.
+ * 
+ */
+package com.mysema.query.util;
+
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * FactoryMap provides
+ *
+ * @author Timo Westk&auml;mper
+ * @version $Id: FactoryMap.java 3549 2008-06-10 17:56:47Z tiwe $
+ */
+public abstract class FactoryMap<V>{
+    
+    private final Map<List<?>,V> cache = new HashMap<List<?>,V>();
+    
+    private Method createMethod;
+    
+    public FactoryMap(){
+        for (Method m : getClass().getMethods()){
+            if (m.getName().equals("create")) createMethod = m;
+        }
+        if (createMethod == null){
+            throw new IllegalArgumentException("No create method given");
+        }else{
+            createMethod.setAccessible(true);
+        }
+    }
+    
+    @SuppressWarnings("unchecked")
+    public final V get(Object... args){
+        List<?> key = Arrays.asList(args);
+        if (cache.containsKey(key)){
+            return cache.get(key);
+        }else{
+            try {
+                V value = (V) createMethod.invoke(this, args);
+                cache.put(key, value);
+                return value;
+            } catch (Exception e) {
+                throw new RuntimeException("error", e);
+            }            
+        }
+    }
+    
+    public void clear(){
+        cache.clear();
+    }
+
+}