Rename load to onLoad and add onDisable to plugin.

src/org/nwapw/abacus/plugin/Plugin.java

@@ -28,6 +28,10 @@ public abstract class Plugin {
      * not inside this package,
      */
     private PluginManager manager;
+    /**
+     * Whether this plugin has been loaded.
+     */
+    private boolean enabled;
 
     private Plugin(){ }
 
@@ -38,6 +42,8 @@ public abstract class Plugin {
     public Plugin(PluginManager manager) {
         this.manager = manager;
         functions = new HashMap<>();
+        operators = new HashMap<>();
+        enabled = false;
     }
 
     /**
@@ -74,6 +80,28 @@ public abstract class Plugin {
         return operators.get(operatorName);
     }
 
+    /**
+     * Enables the function, loading the necessary instances
+     * of functions.
+     */
+    public final void enable(){
+        if(enabled) return;
+        onEnable();
+        enabled = true;
+    }
+
+    /**
+     * Disables the plugin, clearing loaded data store by default
+     * and calling its disable() method.
+     */
+    public final void disable(){
+        if(!enabled) return;
+        onDisable();
+        functions.clear();
+        operators.clear();
+        enabled = false;
+    }
+
     /**
      * To be used in load(). Registers a function abstract class with the
      * plugin internally, which makes it accessible to the plugin manager.
@@ -132,6 +160,12 @@ public abstract class Plugin {
      * are supposed to register the functions they provide and do any other
      * necessary setup.
      */
-    public abstract void load();
+    public abstract void onEnable();
+
+    /**
+     * Abstract method overridden by the plugin implementation, in which the plugins
+     * are supposed to dispose of loaded functions, operators, and macros.
+     */
+    public abstract void onDisable();
 
 }

src/org/nwapw/abacus/plugin/PluginManager.java

@@ -26,6 +26,18 @@ public class PluginManager {
      * that is, found in a plugin and returned.
      */
     private HashMap<String, Operator> cachedOperators;
+    /**
+     * List of all functions loaded by the plugins.
+     */
+    private HashSet<String> allFunctions;
+    /**
+     * List of all operators loaded by the plugins.
+     */
+    private HashSet<String> allOperators;
+    /**
+     * The list of plugin listeners attached to this instance.
+     */
+    private HashSet<PluginListener> listeners;
 
     /**
      * Creates a new plugin manager.
@@ -34,6 +46,8 @@ public class PluginManager {
         plugins = new ArrayList<>();
         cachedFunctions = new HashMap<>();
         cachedOperators = new HashMap<>();
+        allFunctions = new HashSet<>();
+        allOperators = new HashSet<>();
     }
 
     /**
@@ -89,9 +103,6 @@ public class PluginManager {
      * @param plugin the plugin to add.
      */
     public void addInstantiated(Plugin plugin){
-        plugin.load();
-        cachedFunctions.clear();
-        cachedOperators.clear();
         plugins.add(plugin);
     }
 
@@ -109,4 +120,47 @@ public class PluginManager {
         }
     }
 
+    /**
+     * Loads all the plugins in the PluginManager.
+     */
+    public void load(){
+        for(Plugin plugin : plugins) plugin.enable();
+        for(Plugin plugin : plugins){
+            allFunctions.addAll(plugin.providedFunctions());
+            allOperators.addAll(plugin.providedOperators());
+        }
+    }
+
+    /**
+     * Unloads all the plugins in the PluginManager.
+     */
+    public void unload(){
+        for(Plugin plugin : plugins) plugin.disable();
+        allFunctions.clear();
+        allOperators.clear();
+    }
+
+    /**
+     * Reloads all the plugins in the PluginManager.
+     */
+    public void reload(){
+        unload();
+        reload();
+    }
+
+    /**
+     * Gets all the functions loaded by the Plugin Manager.
+     * @return the set of all functions that were loaded.
+     */
+    public HashSet<String> getAllFunctions() {
+        return allFunctions;
+    }
+
+    /**
+     * Gets all the operators loaded by the Plugin Manager.
+     * @return the set of all operators that were loaded.
+     */
+    public HashSet<String> getAllOperators() {
+        return allOperators;
+    }
 }

src/org/nwapw/abacus/plugin/StandardPlugin.java

@@ -17,7 +17,7 @@ public class StandardPlugin extends Plugin {
     }
 
     @Override
-    public void load() {
+    public void onEnable() {
         registerFunction("+", new Function() {
             @Override
             protected boolean matchesParams(NumberInterface[] params) {
@@ -108,6 +108,11 @@ public class StandardPlugin extends Plugin {
         });
     }
 
+    @Override
+    public void onDisable() {
+
+    }
+
     /**
      * Returns the nth term of the Taylor series (centered at 0) of e^x
      * @param n the term required (n >= 0).