support filtering of selects - closes #5, closes #14

src/main/clojure/org/dada/core.clj

@@ -1,7 +1,17 @@
 (ns org.dada.core
     (:import (clojure.lang DynamicClassLoader)
 	     (java.beans PropertyDescriptor)
-	     (org.dada.core Getter GetterMetadata Model Transformer Transformer$Transform Update VersionedModelView View)
+	     (org.dada.core
+	      FilteredView
+	      FilteredView$Filter
+	      Getter
+	      GetterMetadata
+	      Model
+	      Transformer
+	      Transformer$Transform
+	      Update
+	      VersionedModelView
+	      View)
 	     (org.dada.demo Client)
 	     (org.springframework.context.support ClassPathXmlApplicationContext)
 	     (org.dada.asm ClassFactory)))
@@ -138,6 +148,18 @@
      (apply make-instance view-class (map (fn [getter] (getter input)) getters)))
     )))
 
+(defn make-filter [filter-fn view]
+  (FilteredView. 
+   (proxy
+    [FilteredView$Filter]
+    []
+    (filter 
+     [value]
+     ;; TODO: this code needs to be FAST - executed online
+     (filter-fn value)))
+   (list view)
+   ))
+
 ;; (transform input-model src-class property-map input-names view output-class)
 (defn transform [model model-class property-map sel-getters tgt-names view view-class]
   (if (= tgt-names (keys property-map))
@@ -182,7 +204,6 @@
 ;; TODO
 ;; allow selection from a number of src-models
 ;; allow selection into a number of src views
-;; allow filtering :filter <filter-fn>
 ;; allow splitting :split <split-fn> implemented by router - should provide fn for tgt-view construction...
 ;; abstract out tgt-view construction so it can be done from parameters, during select, or on-demand from router...
 
@@ -200,6 +221,7 @@
 	;; what is an :into param was given...none of this needs calculating...
 	tgt-class-name (or (pmap :class) (.toString (gensym "org.dada.tmp.OutputValue")))
 	tgt-model-name (or (pmap :model) (.toString (gensym "OutputModel")))
+	filter-fn (pmap :filter)
    	tgt-types (map (fn [field] (nth field 0)) fields)
    	tgt-names (map (fn [field] (nth field 1)) fields)
    	sel-getters (map (fn [field] (nth field 2)) fields)
@@ -211,7 +233,10 @@
    	tgt-version-getter (tgt-getter-map src-version-name)
 	tgt-metadata (new GetterMetadata tgt-class tgt-types tgt-names tgt-getters)
 	view (VersionedModelView. tgt-model-name tgt-metadata tgt-key-getter tgt-version-getter)
-	transformer (transform src-model src-class src-type-map sel-getters tgt-names view tgt-class)]
+	transformer (make-transformer sel-getters view tgt-class)
+	filter (make-filter filter-fn transformer)
+	]
+    (connect src-model filter)
     view)
   )
 

src/main/clojure/org/dada/demo/whales.clj

@@ -109,5 +109,7 @@
     output))
 
 ;; select whales into a new model...
-(def small (fetch model "time" "version" '(["time"] ["version"] ["type"]) :model "Small"))
-(def smaller (fetch small "time" "version" '(["time"] ["version"]) :model "Smaller"))
+(def narwhals (fetch model "time" "version" '(["time"] ["version"] ["type"]) :model "Narwhals2" :filter (fn [value] (= "narwhal" (. value getType)))))
+
+(def belugas (fetch model "time" "version" '(["time"] ["version"] ["type"]) :model "Belugas" :filter (fn [value] (= "beluga whale" (. value getType)))))
+

src/main/java/org/dada/core/FilteredView.java

@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2009, Julian Gosnell
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *
+ *     * Redistributions in binary form must reproduce the above
+ *     copyright notice, this list of conditions and the following
+ *     disclaimer in the documentation and/or other materials provided
+ *     with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package org.dada.core;
+
+import java.util.ArrayList;
+import java.util.Collection;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class FilteredView<K, V> implements View<K, V> {
+
+	private final Logger logger = LoggerFactory.getLogger(getClass());
+
+	public interface Filter<V> {
+		boolean filter(V value);
+	}
+
+	private final Filter<V> filter;
+	private final Collection<View<K, V>> views;
+
+	public FilteredView(Filter<V> filter, Collection<View<K, V>> views) {
+		this.filter = filter;
+		this.views = views;
+	}
+
+	@Override
+	public void update(Collection<Update<V>> insertions, Collection<Update<V>> updates, Collection<Update<V>> deletions) {
+		Collection<Update<V>> i = new ArrayList<Update<V>>();
+		for (Update<V> insertion : insertions) {
+			if (filter.filter(insertion.getNewValue()))
+				i.add(insertion);
+		}
+		Collection<Update<V>> u = new ArrayList<Update<V>>();
+		for (Update<V> update : updates) {
+			if (filter.filter(update.getOldValue()))
+				u.add(update);
+		}
+		Collection<Update<V>> d = new ArrayList<Update<V>>();
+		for (Update<V> deletion : deletions) {
+			if (filter.filter(deletion.getOldValue()))
+				d.add(deletion);
+		}
+
+		for (View<K, V> view: views) {
+			try {
+				view.update(i, u, d);
+			} catch (Throwable t) {
+				logger.error("problem updating View: ", t);
+			}
+		}
+
+	}
+
+}