gpclient: adding CollectorExpression

Author: gcarcassi

gpclient/gpclient-core/src/main/java/org/epics/gpclient/CollectorExpression.java

@@ -0,0 +1,71 @@
+/**
+ * Copyright information and license terms for this software can be
+ * found in the file LICENSE.TXT included with the distribution.
+ */
+package org.epics.gpclient;
+
+/**
+ * A {@link ChannelExpression} that exposes its {@link ReadCollector} and {@link WriteCollector}.
+ *
+ * @author carcassi
+ */
+public class CollectorExpression<R, C ,W> extends ChannelExpression<R, W> {
+    
+    private boolean readConnected;
+    private boolean writeConnected;
+
+    /**
+     * A new collector expression.
+     * 
+     */
+    CollectorExpression(ReadCollector<C, R> readCollector, WriteCollector<W> writeCollector) {
+        super(readCollector, writeCollector);
+    }
+
+    @Override
+    protected void connectRead(PVDirector pvDirector) {
+        readConnected = true;
+    }
+
+    @Override
+    protected void disconnectRead(PVDirector director) {
+    }
+
+    @Override
+    protected void connectWrite(PVDirector pvDirector) {
+        writeConnected = true;
+    }
+
+    @Override
+    protected void disconnectWrite(PVDirector pvDirector) {
+    }
+
+    /**
+     * Retrieves the collector that can be used to send updates to the reader.
+     * Note that the PVReader must first be started.
+     * 
+     * @return the read collector
+     */
+    @Override
+    public ReadCollector<C, R> getReadCollector() {
+        if (!readConnected) {
+            throw new IllegalStateException("PVReader was not started");
+        }
+        return (ReadCollector<C, R>) super.getReadCollector();
+    }
+
+    /**
+     * Retrieves the collector that can be used to send/receives updates
+     * from the writer. Note that the PVWrite must first be started.
+     * 
+     * @return the write collecto
+     */
+    @Override
+    protected WriteCollector<W> getWriteCollector() {
+        if (!writeConnected) {
+            throw new IllegalStateException("PVWriter was not started");
+        }
+        return super.getWriteCollector();
+    }
+    
+}

gpclient/gpclient-core/src/main/java/org/epics/gpclient/GPClient.java

@@ -169,6 +169,47 @@ public static Expression<VType, Object> channel(String channelName) {
         return channel(channelName, cacheLastValue(VType.class));
     }
 
+    /**
+     * An expression that allows to directly send/receive values to/from
+     * PVReaders/PVWriters. This can be used for testing purpose or to integrate
+     * data models that do not fit datasources or services.
+     * 
+     * @param <R> the type to read
+     * @param <C> the type to collect
+     * @param <W> the type to write
+     * @param readCollector the read buffer
+     * @param writeCollector the write buffer
+     * @return a new collector expression
+     */
+    public static <R, C, W> CollectorExpression<R, C, W> collector(ReadCollector<C, R> readCollector, WriteCollector<W> writeCollector) {
+        return new CollectorExpression<>(readCollector, writeCollector);
+    }
+
+    /**
+     * An expression that allows to directly send/receive values to/from
+     * PVReaders/PVWriters. This can be used for testing purpose or to integrate
+     * data models that do not fit datasources or services.
+     * 
+     * @param <R> the type to read
+     * @param <C> the type to collect
+     * @param readCollector the read buffer
+     * @return a new collector expression
+     */
+    public static <R, C> CollectorExpression<R, C, Object> collector(ReadCollector<C, R> readCollector) {
+        return collector(readCollector, new WriteCollector<>());
+    }
+
+    /**
+     * An expression that allows to directly send/receive values to/from
+     * PVReaders/PVWriters. This can be used for testing purpose or to integrate
+     * data models that do not fit datasources or services.
+     * 
+     * @return a new collector expression
+     */
+    public static CollectorExpression<VType, VType, Object> collector() {
+        return collector(cacheLastValue(VType.class));
+    }
+
     /**
      * The default instance of the general purpose client.
      *