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

@@ -4,26 +4,61 @@ import org.nwapw.abacus.function.Function;
 
 import java.util.HashMap;
 
+/**
+ * A plugin class that can be externally implemented and loaded via the
+ * plugin manager. Plugins provide functionality to the calculator
+ * with the "hasFunction" and "getFunction" functions,
+ * and can use "registerFunction" and "functionFor" for
+ * loading internally.
+ */
 public abstract class Plugin {
 
+    /**
+     * A hash map of functions mapped to their string names.
+     */
     private HashMap<String, Function> functions;
+    /**
+     * The plugin manager in which to search for functions
+     * not inside this package,
+     */
     private PluginManager manager;
 
     private Plugin(){ }
 
+    /**
+     * Creates a new plugin with the given PluginManager.
+     * @param manager the manager controlling this plugin.
+     */
     public Plugin(PluginManager manager) {
         this.manager = manager;
         functions = new HashMap<>();
     }
 
+    /**
+     * Determines whether the current plugin provides the given function name.
+     * @param functionName the name of the function provided.
+     * @return true of the function exists, false if it doesn't.
+     */
     public final boolean hasFunction(String functionName) {
         return functions.containsKey(functionName);
     }
 
+    /**
+     * Gets a function under the given function name.
+     * @param functionName the name of the function to get
+     * @return the function, or null if this plugin doesn't provide it.
+     */
     public final Function getFunction(String functionName) {
         return functions.get(functionName);
     }
 
+    /**
+     * To be used in load(). Registers a function abstract class with the
+     * plugin internally, which makes it accessible to the plugin manager.
+     * @param name the name to register by.
+     * @param toRegister the function implementation.
+     * @return true if the function was registered successfully, false if not.
+     */
     protected final boolean registerFunction(String name, Function toRegister) {
         if(functionFor(name) == null){
             functions.put(name, toRegister);
@@ -32,12 +67,22 @@ public abstract class Plugin {
         return false;
     }
 
+    /**
+     * Searches the PluginManager for the given function name.
+     * This can be used by the plugins internally in order to call functions
+     * they do not provide.
+     * @param name then name for which to search
+     * @return the resulting function, or null if none was found for that name.
+     */
     protected final Function functionFor(String name) {
-        Plugin ownerPlugin = manager.pluginForFunction(name);
-        if(ownerPlugin == null) return null;
-        return ownerPlugin.getFunction(name);
+        return manager.functionFor(name);
     }
 
+    /**
+     * Abstract method to be overridden by plugin implementation, in which the plugins
+     * are supposed to register the functions they provide and do any other
+     * necessary setup.
+     */
     public abstract void load();
 
 }

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

@@ -4,6 +4,10 @@ import org.nwapw.abacus.function.Function;
 import org.nwapw.abacus.number.NaiveNumber;
 import org.nwapw.abacus.number.NumberInterface;
 
+/**
+ * The plugin providing standard functions such as addition and subtraction to
+ * the calculator.
+ */
 public class StandardPlugin extends Plugin {
 
     public StandardPlugin(PluginManager manager) {