From 7c279747beb43c7e88633a6228a155a30e6834f7 Mon Sep 17 00:00:00 2001
From: Benjamin Culkin <scorpress@gmail.com>
Date: Mon, 27 May 2024 11:38:33 -0400
Subject: Initial import

---
 .../israfil/foundation/valuemodel/ValueHolder.java | 108 +++++++++++++++++++++
 1 file changed, 108 insertions(+)
 create mode 100644 israfil-foundation-valuemodel/src/main/java/net/israfil/foundation/valuemodel/ValueHolder.java

(limited to 'israfil-foundation-valuemodel/src/main/java/net/israfil/foundation/valuemodel/ValueHolder.java')

diff --git a/israfil-foundation-valuemodel/src/main/java/net/israfil/foundation/valuemodel/ValueHolder.java b/israfil-foundation-valuemodel/src/main/java/net/israfil/foundation/valuemodel/ValueHolder.java
new file mode 100644
index 0000000..55f23c3
--- /dev/null
+++ b/israfil-foundation-valuemodel/src/main/java/net/israfil/foundation/valuemodel/ValueHolder.java
@@ -0,0 +1,108 @@
+/*
+ * Created on Dec 8, 2003
+ *
+ * To change the template for this generated file go to
+ * Window>Preferences>Java>Code Generation>Code and Comments
+ */
+package net.israfil.foundation.valuemodel;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import net.israfil.foundation.dynamic.DynamicUtil;
+
+
+/**
+ * @author cgruber
+ *
+ * To change the template for this generated type comment go to
+ * Window>Preferences>Java>Code Generation>Code and Comments
+ */
+public class ValueHolder<E> implements MutableValue<E> {
+
+    private E _value = null;
+    private Map<Integer, ObserverHolder> _observers = new HashMap<Integer, ObserverHolder>();
+    private Map<Integer, VetoerHolder> _vetoers = new HashMap<Integer, VetoerHolder>();
+
+	public ValueHolder(E o) {
+		set(o); 
+	}
+        
+    protected ValueHolder() { }
+
+	public E get() {
+		return _value;
+	}
+
+    public void set(E newValue) {
+        boolean approved = true;
+        E oldValue = _value;
+        for (VetoerHolder vetoer : _vetoers.values()) {
+        	approved &= vetoer.evaluate(this, oldValue, newValue);
+        }
+        
+        if (!approved) return;
+        else _value = newValue;
+        for (ObserverHolder observer : _observers.values()) {
+            observer.notify(this, oldValue, newValue);
+        }
+        
+    }
+
+	/**
+	 * @see org.israfil.maveric.Observable#addObserver(java.lang.Object, java.lang.String)
+	 */
+	public void addObservers(String callback, Object ... observers) {
+    	for (Object observer : observers) {
+    		_observers.put(observer.hashCode(),new ObserverHolder(observer,callback));
+    	}
+	}
+
+	/**
+     * @see org.israfil.maveric.Observable#removeObserver(java.lang.Object)
+	 */
+	public void removeObservers(Object ... observers) {
+    	for (Object observer : observers) {
+    		_observers.remove(observer.hashCode());
+    	}
+	}
+    /**
+     * @see org.israfil.maveric.Vetoable#addVetoer(java.lang.Object, java.lang.String)
+     */
+    public void addVetoers(String callback, Object ... vetoers) {
+    	for (Object vetoer : vetoers) {
+    		_vetoers.put(vetoer.hashCode(),new VetoerHolder(vetoer,callback));
+    	}
+    }
+
+    /**
+     * @see org.israfil.maveric.Vetoable#removeVetoer(java.lang.Object)
+     */
+    public void removeVetoers(Object ... vetoers) {
+    	for (Object vetoer : vetoers) {
+    		_vetoers.remove(vetoer.hashCode());
+    	}
+    }
+
+    protected class CallbackObjectHolder {
+        public final Object receiver;
+        protected final String callback; 
+        public CallbackObjectHolder(Object receiver, String callback) {
+            this.receiver = receiver;
+            this.callback = callback;
+        }
+    }
+    protected class ObserverHolder extends CallbackObjectHolder {
+        public ObserverHolder(Object observer, String callback) { super(observer, callback); }
+        public void notify(Object notifier, Object oldValue, Object newValue) {
+            DynamicUtil.performOn(receiver,callback,new Object[]{notifier, oldValue , newValue});
+        }
+    }
+    protected class VetoerHolder extends CallbackObjectHolder {
+        public VetoerHolder(Object vetoer, String callback) { super(vetoer, callback); }
+        public Boolean evaluate(Object notifier, Object oldValue, Object newValue) {
+            Boolean result = (Boolean)DynamicUtil.performOn(receiver,callback,new Object[]{notifier,oldValue,newValue});
+            return (result == null) ? true : result.booleanValue();
+        }
+    }
+}
-- 
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