Add tree value functions to plugins.

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

@@ -1,9 +1,6 @@
 package org.nwapw.abacus.plugin;
 
-import org.nwapw.abacus.function.Documentation;
+import org.nwapw.abacus.function.*;
-import org.nwapw.abacus.function.DocumentationType;
-import org.nwapw.abacus.function.Function;
-import org.nwapw.abacus.function.Operator;
 import org.nwapw.abacus.number.NumberInterface;
 
 /**
@@ -69,6 +66,17 @@ public abstract class Plugin {
         manager.registerFunction(name, toRegister);
     }
 
+    /**
+     * To be used in load(). Registers a tree value 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 tree value function implementation.
+     */
+    protected final void registerTreeValueFunction(String name, TreeValueFunction toRegister) {
+        manager.registerTreeValueFunction(name, toRegister);
+    }
+
     /**
      * To be used in load(). Registers an operator abstract class
      * with the plugin internally, which makes it accessible to
@@ -114,6 +122,18 @@ public abstract class Plugin {
         return manager.functionFor(name);
     }
 
+    /**
+     * 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 the name for which to search.
+     * @return the resulting tree value function, or null if none was found for that name.
+     */
+    protected final TreeValueFunction treeValueFunctionFor(String name){
+        return manager.treeValueFunctionFor(name);
+    }
+
     /**
      * Searches the PluginManager for the given operator name.
      * This can be used by the plugins internally in order to call

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

@@ -1,10 +1,7 @@
 package org.nwapw.abacus.plugin;
 
 import org.nwapw.abacus.Abacus;
-import org.nwapw.abacus.function.Documentation;
+import org.nwapw.abacus.function.*;
-import org.nwapw.abacus.function.DocumentationType;
-import org.nwapw.abacus.function.Function;
-import org.nwapw.abacus.function.Operator;
 import org.nwapw.abacus.number.NumberInterface;
 
 import java.lang.reflect.InvocationTargetException;
@@ -31,6 +28,10 @@ public class PluginManager {
      * The map of functions registered by the plugins.
      */
     private Map<String, Function> registeredFunctions;
+    /**
+     * The map of tree value functions regstered by the plugins.
+     */
+    private Map<String, TreeValueFunction> registeredTreeValueFunctions;
     /**
      * The map of operators registered by the plugins
      */
@@ -72,6 +73,7 @@ public class PluginManager {
         loadedPluginClasses = new HashSet<>();
         plugins = new HashSet<>();
         registeredFunctions = new HashMap<>();
+        registeredTreeValueFunctions = new HashMap<>();
         registeredOperators = new HashMap<>();
         registeredNumberImplementations = new HashMap<>();
         registeredDocumentation = new HashSet<>();
@@ -90,6 +92,16 @@ public class PluginManager {
         registeredFunctions.put(name, function);
     }
 
+    /**
+     * Registers a tree value function under the given name.
+     *
+     * @param name the name of the function.
+     * @param function the function to register.
+     */
+    public void registerTreeValueFunction(String name, TreeValueFunction function) {
+        registeredTreeValueFunctions.put(name, function);
+    }
+
     /**
      * Registers an operator under the given name.
      *
@@ -130,6 +142,16 @@ public class PluginManager {
         return registeredFunctions.get(name);
     }
 
+    /**
+     * Gets the tree value function registered under the given name.
+     *
+     * @param name the name of the function.
+     * @return the function, or null if it was not found.
+     */
+    public TreeValueFunction treeValueFunctionFor(String name){
+        return registeredTreeValueFunctions.get(name);
+    }
+
     /**
      * Gets the operator registered under the given name.
      *
@@ -302,6 +324,15 @@ public class PluginManager {
         return registeredFunctions.keySet();
     }
 
+    /**
+     * Gets all the tree vlaue functions loaded by the PluginManager.
+     *
+     * @return the set of all the tree value functions that were loaded.
+     */
+    public Set<String> getAllTreeValueFunctions() {
+        return registeredTreeValueFunctions.keySet();
+    }
+
     /**
      * Gets all the operators loaded by the Plugin Manager.
      *