Native code in Prism only loaded/initialised on demand.

Native shared libraries can be absent when using the explicit engine.

Author: davexparker

prism/src/prism/Prism.java

@@ -1293,14 +1293,31 @@ public void initialise() throws PrismException
 		}
 		mainLog.print("Memory limits: cudd=" + getCUDDMaxMem());
 		mainLog.println(", java(heap)=" + PrismUtils.convertBytesToMemoryString(Runtime.getRuntime().maxMemory()));
+	}
 
-		// Add/initialise components/libraries
-		libraries.add(new JDDLibrary());
-		libraries.add(new PrismNativeLibrary());
-		for (PrismLibrary lib : libraries) {
-			lib.initialise(this);
+	/**
+	 * Ensure that the native libraries are loaded and initialised,
+	 * and that any relevant settings are passed to them.
+	 */
+	public void useNative() throws PrismException
+	{
+		// Add/initialise libraries for native code, if not already done
+		if (libraries.stream().noneMatch(JDDLibrary.class::isInstance)) {
+			addLibrary(new JDDLibrary());
+		}
+		if (libraries.stream().noneMatch(PrismNativeLibrary.class::isInstance)) {
+			addLibrary(new PrismNativeLibrary());
 		}
-		setMainLog(mainLog);
+	}
+
+	/**
+	 * Initialise a freshy created {@link PrismLibrary} and add to the list of libraries.
+	 */
+	private void addLibrary(PrismLibrary lib) throws PrismException
+	{
+		lib.initialise(this);
+		lib.setMainLog(mainLog);
+		libraries.add(lib);
 	}
 
 	/**

prism/src/prism/PrismNativeComponent.java

@@ -38,5 +38,7 @@ public PrismNativeComponent(Prism prism) throws PrismException
     {
         super(prism);
         this.prism = prism;
+        // Make sure PRISM is set up to use native code.
+        prism.useNative();
     }
 }