Fix some documentation glitches.

# Conflicts:
#	src/main/java/org/nwapw/abacus/plugin/StandardPlugin.java

build.gradle

@@ -1,3 +1,8 @@
+plugins {
+    id 'java'
+    id 'application'
+    id 'org.jetbrains.kotlin.jvm' version '1.1.3'
+}
 apply plugin: 'java'
 apply plugin: 'application'
 
@@ -7,6 +12,7 @@ repositories {
 
 dependencies {
     compile 'com.moandjiezana.toml:toml4j:0.7.1'
+    compile "org.jetbrains.kotlin:kotlin-stdlib-jre8"
     testCompile 'junit:junit:4.12'
 }
 

src/main/java/org/nwapw/abacus/function/DocumentationType.java

@@ -0,0 +1,7 @@
+package org.nwapw.abacus.function;
+
+public enum DocumentationType {
+
+    FUNCTION
+
+}

src/main/java/org/nwapw/abacus/function/Operator.java

@@ -1,76 +0,0 @@
-package org.nwapw.abacus.function;
-
-/**
- * A class that represents a single infix operator.
- */
-public class Operator {
-
-    /**
-     * The associativity of the operator.
-     */
-    private OperatorAssociativity associativity;
-    /**
-     * The type of this operator.
-     */
-    private OperatorType type;
-    /**
-     * The precedence of the operator.
-     */
-    private int precedence;
-    /**
-     * The function that is called by this operator.
-     */
-    private Function function;
-
-    /**
-     * Creates a new operator with the given parameters.
-     *
-     * @param associativity the associativity of the operator.
-     * @param operatorType  the type of this operator, like binary infix or unary postfix.
-     * @param precedence    the precedence of the operator.
-     * @param function      the function that the operator calls.
-     */
-    public Operator(OperatorAssociativity associativity, OperatorType operatorType, int precedence, Function function) {
-        this.associativity = associativity;
-        this.type = operatorType;
-        this.precedence = precedence;
-        this.function = function;
-    }
-
-    /**
-     * Gets the operator's associativity.
-     *
-     * @return the associativity.
-     */
-    public OperatorAssociativity getAssociativity() {
-        return associativity;
-    }
-
-    /**
-     * Gets the operator's type.
-     *
-     * @return the type.
-     */
-    public OperatorType getType() {
-        return type;
-    }
-
-    /**
-     * Gets the operator's precedence.
-     *
-     * @return the precedence.
-     */
-    public int getPrecedence() {
-        return precedence;
-    }
-
-    /**
-     * Gets the operator's function.
-     *
-     * @return the function.
-     */
-    public Function getFunction() {
-        return function;
-    }
-
-}

src/main/java/org/nwapw/abacus/fx/AbacusController.java

@@ -5,7 +5,9 @@ import javafx.beans.value.ChangeListener;
 import javafx.beans.value.ObservableValue;
 import javafx.collections.FXCollections;
 import javafx.collections.ObservableList;
+import javafx.collections.transformation.FilteredList;
 import javafx.fxml.FXML;
+import javafx.scene.Node;
 import javafx.scene.control.*;
 import javafx.scene.control.cell.CheckBoxListCell;
 import javafx.scene.text.Text;
@@ -13,6 +15,8 @@ import javafx.util.Callback;
 import javafx.util.StringConverter;
 import org.nwapw.abacus.Abacus;
 import org.nwapw.abacus.config.Configuration;
+import org.nwapw.abacus.function.Documentation;
+import org.nwapw.abacus.function.DocumentationType;
 import org.nwapw.abacus.number.ComputationInterruptedException;
 import org.nwapw.abacus.number.NumberInterface;
 import org.nwapw.abacus.plugin.ClassFinder;
@@ -23,7 +27,10 @@ import org.nwapw.abacus.tree.TreeNode;
 
 import java.io.File;
 import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Comparator;
 import java.util.Set;
+import java.util.stream.Collectors;
 
 
 /**
@@ -72,6 +79,8 @@ public class AbacusController implements PluginListener {
     @FXML
     private Tab settingsTab;
     @FXML
+    private Tab functionListTab;
+    @FXML
     private TableView<HistoryModel> historyTable;
     @FXML
     private TableColumn<HistoryModel, String> inputColumn;
@@ -93,6 +102,10 @@ public class AbacusController implements PluginListener {
     private ListView<ToggleablePlugin> enabledPluginView;
     @FXML
     private TextField computationLimitField;
+    @FXML
+    private ListView<Documentation> functionListView;
+    @FXML
+    private TextField functionListSearchField;
 
     /**
      * The list of history entries, created by the users.
@@ -110,6 +123,14 @@ public class AbacusController implements PluginListener {
      * and, when reloaded, get added to the plugin manager's black list.
      */
     private ObservableList<ToggleablePlugin> enabledPlugins;
+    /**
+     * The list of functions that are registered in the calculator.
+     */
+    private ObservableList<Documentation> functionList;
+    /**
+     * The filtered list displayed to the user.
+     */
+    private FilteredList<Documentation> functionFilter;
 
     /**
      * The abacus instance used for changing the plugin configuration.
@@ -212,7 +233,12 @@ public class AbacusController implements PluginListener {
                         return new ToggleablePlugin(true, string);
                     }
                 });
-
+        functionList = FXCollections.observableArrayList();
+        functionFilter = new FilteredList<>(functionList, (s) -> true);
+        functionListView.setItems(functionFilter);
+        functionListSearchField.textProperty().addListener((observable, oldValue, newValue) ->
+                functionFilter.setPredicate((newValue.length() == 0) ? ((s) -> true) : ((s) -> s.matches(newValue))));
+        functionListView.setCellFactory(param -> new DocumentationCell());
         historyData = FXCollections.observableArrayList();
         historyTable.setItems(historyData);
         numberImplementationOptions = FXCollections.observableArrayList();
@@ -327,10 +353,15 @@ public class AbacusController implements PluginListener {
             plugin.enabledProperty().addListener(e -> changesMade = true);
             enabledPlugins.add(plugin);
         }
+        PluginManager pluginManager = abacus.getPluginManager();
+        functionList.addAll(manager.getAllFunctions().stream().map(name -> pluginManager.documentationFor(name, DocumentationType.FUNCTION))
+                .collect(Collectors.toCollection(ArrayList::new)));
+        functionList.sort(Comparator.comparing(Documentation::getCodeName));
     }
 
     @Override
     public void onUnload(PluginManager manager) {
+        functionList.clear();
         enabledPlugins.clear();
         numberImplementationOptions.clear();
     }

src/main/java/org/nwapw/abacus/fx/DocumentationCell.java

@@ -0,0 +1,58 @@
+package org.nwapw.abacus.fx;
+
+import javafx.scene.control.Label;
+import javafx.scene.control.ListCell;
+import javafx.scene.control.TitledPane;
+import javafx.scene.layout.VBox;
+import org.nwapw.abacus.function.Documentation;
+
+public class DocumentationCell extends ListCell<Documentation> {
+
+    private Label codeNameLabel;
+    private Label nameLabel;
+    private Label description;
+    private Label longDescription;
+    private TitledPane titledPane;
+
+    public DocumentationCell(){
+        VBox vbox = new VBox();
+        vbox.setSpacing(10);
+        titledPane = new TitledPane();
+        codeNameLabel = new Label();
+        nameLabel = new Label();
+        description = new Label();
+        longDescription = new Label();
+        codeNameLabel.setWrapText(true);
+        nameLabel.setWrapText(true);
+        description.setWrapText(true);
+        longDescription.setWrapText(true);
+        vbox.getChildren().add(codeNameLabel);
+        vbox.getChildren().add(nameLabel);
+        vbox.getChildren().add(description);
+        vbox.getChildren().add(longDescription);
+        titledPane.textProperty().bindBidirectional(codeNameLabel.textProperty());
+        titledPane.setContent(vbox);
+        titledPane.setExpanded(false);
+        titledPane.prefWidthProperty().bind(widthProperty());
+
+        visibleProperty().addListener((a, b, c) -> titledPane.setExpanded(false));
+    }
+
+    @Override
+    protected void updateItem(Documentation item, boolean empty) {
+        super.updateItem(item, empty);
+        if(empty){
+            codeNameLabel.setText("");
+            nameLabel.setText("");
+            description.setText("");
+            longDescription.setText("");
+            setGraphic(null);
+        } else {
+            codeNameLabel.setText(item.getCodeName());
+            nameLabel.setText(item.getName());
+            description.setText(item.getDescription());
+            longDescription.setText(item.getLongDescription());
+            setGraphic(titledPane);
+        }
+    }
+}

src/main/java/org/nwapw/abacus/number/NumberInterface.java

@@ -173,7 +173,7 @@ public abstract class NumberInterface {
     /**
      * Returns the least integer greater than or equal to the number.
      *
-     * @return the least integer >= the number, if int can hold the value.
+     * @return the least integer greater or equal to the number, if int can hold the value.
      */
     protected abstract NumberInterface ceilingInternal();
 
@@ -182,7 +182,7 @@ public abstract class NumberInterface {
      * Also, checks if the thread has been interrupted, and if so, throws
      * an exception.
      *
-     * @return the least integer bigger or equal to the number, if int can hold the value.
+     * @return the least integer bigger or equal to the number.
      */
     public final NumberInterface ceiling(){
         checkInterrupted();
@@ -192,7 +192,7 @@ public abstract class NumberInterface {
     /**
      * Return the greatest integer less than or equal to the number.
      *
-     * @return the greatest integer smaller or equal the number, if int can hold the value.
+     * @return the greatest integer smaller or equal the number.
      */
     protected abstract NumberInterface floorInternal();
 
@@ -201,7 +201,7 @@ public abstract class NumberInterface {
      * Also, checks if the thread has been interrupted, and if so, throws
      * an exception.
      *
-     * @return the greatest int >= the number, if int can hold the value.
+     * @return the greatest int smaller than or equal to the number.
      */
     public final NumberInterface floor(){
         checkInterrupted();
@@ -216,7 +216,7 @@ public abstract class NumberInterface {
     protected abstract NumberInterface fractionalPartInternal();
 
     /**
-     * Returns the fractional part of the number.
+     * Returns the fractional part of the number, specifically x - floor(x).
      * Also, checks if the thread has been interrupted,
      * and if so, throws an exception.
      * @return the fractional part of the number.

src/main/java/org/nwapw/abacus/number/PreciseNumber.java

@@ -113,19 +113,18 @@ public class PreciseNumber extends NumberInterface {
         String str = value.toPlainString();
         int decimalIndex = str.indexOf('.');
         if (decimalIndex != -1) {
-            return new PreciseNumber(str.substring(0, decimalIndex));
+            NumberInterface floor = new PreciseNumber(str.substring(0, decimalIndex));
+            if(signum() == -1){
+                floor = floor.subtract(ONE);
+            }
+            return floor;
         }
         return this;
     }
 
     @Override
     public NumberInterface fractionalPartInternal() {
-        String str = value.toPlainString();
+        return this.subtractInternal(floorInternal());
-        int decimalIndex = str.indexOf('.');
-        if (decimalIndex != -1) {
-            return new PreciseNumber(str.substring(decimalIndex + 1));
-        }
-        return ZERO;
     }
 
     @Override

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

@@ -1,5 +1,7 @@
 package org.nwapw.abacus.plugin;
 
+import org.nwapw.abacus.function.Documentation;
+import org.nwapw.abacus.function.DocumentationType;
 import org.nwapw.abacus.function.Function;
 import org.nwapw.abacus.function.Operator;
 import org.nwapw.abacus.number.NumberInterface;
@@ -17,18 +19,6 @@ import java.util.Set;
  */
 public abstract class Plugin {
 
-    /**
-     * A hash map of functions mapped to their string names.
-     */
-    private Map<String, Function> functions;
-    /**
-     * A hash map of operators mapped to their string names.
-     */
-    private Map<String, Operator> operators;
-    /**
-     * The map of the number implementations this plugin provides.
-     */
-    private Map<String, NumberImplementation> numberImplementations;
     /**
      * The plugin manager in which to search for functions
      * not inside this package,
@@ -49,69 +39,9 @@ public abstract class Plugin {
      */
     public Plugin(PluginManager manager) {
         this.manager = manager;
-        functions = new HashMap<>();
-        operators = new HashMap<>();
-        numberImplementations = new HashMap<>();
         enabled = false;
     }
 
-    /**
-     * Gets the list of functions provided by this plugin.
-     *
-     * @return the list of registered functions.
-     */
-    public final Set<String> providedFunctions() {
-        return functions.keySet();
-    }
-
-    /**
-     * Gets the list of functions provided by this plugin.
-     *
-     * @return the list of registered functions.
-     */
-    public final Set<String> providedOperators() {
-        return operators.keySet();
-    }
-
-    /**
-     * Gets the list of number implementations provided by this plugin.
-     *
-     * @return the list of registered number implementations.
-     */
-    public final Set<String> providedNumberImplementations() {
-        return numberImplementations.keySet();
-    }
-
-    /**
-     * 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);
-    }
-
-    /**
-     * Gets an operator under the given operator name.
-     *
-     * @param operatorName the name of the operator to get.
-     * @return the operator, or null if this plugin doesn't provide it.
-     */
-    public final Operator getOperator(String operatorName) {
-        return operators.get(operatorName);
-    }
-
-    /**
-     * Gets the number implementation under the given name.
-     *
-     * @param name the name of the number implementation to look up.
-     * @return the number implementation associated with that name, or null if the plugin doesn't provide it.
-     */
-    public final NumberImplementation getNumberImplementation(String name) {
-        return numberImplementations.get(name);
-    }
-
     /**
      * Enables the function, loading the necessary instances
      * of functions.
@@ -129,8 +59,6 @@ public abstract class Plugin {
     public final void disable() {
         if (!enabled) return;
         onDisable();
-        functions.clear();
-        operators.clear();
         enabled = false;
     }
 
@@ -142,7 +70,7 @@ public abstract class Plugin {
      * @param toRegister the function implementation.
      */
     protected final void registerFunction(String name, Function toRegister) {
-        functions.put(name, toRegister);
+        manager.registerFunction(name, toRegister);
     }
 
     /**
@@ -154,7 +82,7 @@ public abstract class Plugin {
      * @param operator the operator to register.
      */
     protected final void registerOperator(String name, Operator operator) {
-        operators.put(name, operator);
+        manager.registerOperator(name, operator);
     }
 
     /**
@@ -165,7 +93,16 @@ public abstract class Plugin {
      * @param implementation the actual implementation class to register.
      */
     protected final void registerNumberImplementation(String name, NumberImplementation implementation) {
-        numberImplementations.put(name, implementation);
+        manager.registerNumberImplementation(name, implementation);
+    }
+
+    /**
+     * To be used in load(). Registers a documentation instance
+     * used to explain some element of the plugin to the user.
+     * @param documentation the documentation instance.
+     */
+    protected final void registerDocumentation(Documentation documentation){
+        manager.registerDocumentation(documentation);
     }
 
     /**
@@ -204,6 +141,17 @@ public abstract class Plugin {
         return manager.numberImplementationFor(name);
     }
 
+    /**
+     * Searches the PluginManager for the given documentation name and type.
+     *
+     * @param name the name for which to search.
+     * @param type the type of documentation to search for.
+     * @return the found documentation, or null if none was found.
+     */
+    protected final Documentation documentationFor(String name, DocumentationType type){
+        return manager.documentationFor(name, type);
+    }
+
     /**
      * Searches the plugin manager for a Pi value for the given number implementation.
      * This is done so that number implementations with various degrees of precision
@@ -213,7 +161,7 @@ public abstract class Plugin {
      * @param forClass the class to which to find the pi instance.
      * @return the pi value for the given class.
      */
-    protected final NumberInterface getPi(Class<? extends NumberInterface> forClass) {
+    protected final NumberInterface piFor(Class<? extends NumberInterface> forClass) {
         return manager.piFor(forClass);
     }
 

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

@@ -1,6 +1,8 @@
 package org.nwapw.abacus.plugin;
 
 import org.nwapw.abacus.Abacus;
+import org.nwapw.abacus.function.Documentation;
+import org.nwapw.abacus.function.DocumentationType;
 import org.nwapw.abacus.function.Function;
 import org.nwapw.abacus.function.Operator;
 import org.nwapw.abacus.number.NumberInterface;
@@ -23,20 +25,21 @@ public class PluginManager {
      */
     private Set<Plugin> plugins;
     /**
-     * List of functions that have been cached,
+     * The map of functions registered by the plugins.
-     * that is, found in a plugin and returned.
      */
-    private Map<String, Function> cachedFunctions;
+    private Map<String, Function> registeredFunctions;
     /**
-     * List of operators that have been cached,
+     * The map of operators registered by the plugins
-     * that is, found in a plugin and returned.
      */
-    private Map<String, Operator> cachedOperators;
+    private Map<String, Operator> registeredOperators;
     /**
-     * The list of number implementations that have
+     * The map of number implementations registered by the plugins.
-     * been cached, that is, found in a plugin and returned.
      */
-    private Map<String, NumberImplementation> cachedNumberImplementations;
+    private Map<String, NumberImplementation> registeredNumberImplementations;
+    /**
+     * The map of documentation for functions registered by the plugins.
+     */
+    private Set<Documentation> registeredDocumentation;
     /**
      * The list of number implementations that have been
      * found by their implementation class.
@@ -46,18 +49,6 @@ public class PluginManager {
      * The pi values for each implementation class that have already been computer.
      */
     private Map<Class<? extends NumberInterface>, NumberInterface> cachedPi;
-    /**
-     * List of all functions loaded by the plugins.
-     */
-    private Set<String> allFunctions;
-    /**
-     * List of all operators loaded by the plugins.
-     */
-    private Set<String> allOperators;
-    /**
-     * List of all the number implementations loaded by the plugins.
-     */
-    private Set<String> allNumberImplementations;
     /**
      * The list of plugin listeners attached to this instance.
      */
@@ -77,79 +68,97 @@ public class PluginManager {
         this.abacus = abacus;
         loadedPluginClasses = new HashSet<>();
         plugins = new HashSet<>();
-        cachedFunctions = new HashMap<>();
+        registeredFunctions = new HashMap<>();
-        cachedOperators = new HashMap<>();
+        registeredOperators = new HashMap<>();
-        cachedNumberImplementations = new HashMap<>();
+        registeredNumberImplementations = new HashMap<>();
+        registeredDocumentation = new HashSet<>();
         cachedInterfaceImplementations = new HashMap<>();
         cachedPi = new HashMap<>();
-        allFunctions = new HashSet<>();
-        allOperators = new HashSet<>();
-        allNumberImplementations = new HashSet<>();
         listeners = new HashSet<>();
     }
 
     /**
-     * Searches the plugin list for a certain value, retrieving the Plugin's
+     * Registers a function under the given name.
-     * list of items of the type using the setFunction and getting the value
+     * @param name the name of the function.
-     * of it is available via getFunction. If the value is contained
+     * @param function the function to register.
-     * in the cache, it returns the cached value instead.
-     *
-     * @param plugins     the plugin list to search.
-     * @param cache       the cache to use
-     * @param setFunction the function to retrieve a set of available T's from the plugin
-     * @param getFunction the function to get the T value under the given name
-     * @param name        the name to search for
-     * @param <T>         the type of element being search
-     * @param <K>         the type of key that the cache is indexed by.
-     * @return the retrieved element, or null if it was not found.
      */
-    private static <T, K> T searchCached(Collection<Plugin> plugins, Map<K, T> cache,
+    public void registerFunction(String name, Function function){
-                                         java.util.function.Function<Plugin, Set<K>> setFunction,
+        registeredFunctions.put(name, function);
-                                         java.util.function.BiFunction<Plugin, K, T> getFunction,
+    }
-                                         K name) {
-        if (cache.containsKey(name)) return cache.get(name);
 
-        T loadedValue = null;
+    /**
-        for (Plugin plugin : plugins) {
+     * Registers an operator under the given name.
-            if (setFunction.apply(plugin).contains(name)) {
+     * @param name the name of the operator.
-                loadedValue = getFunction.apply(plugin, name);
+     * @param operator the operator to register.
+     */
+    public void registerOperator(String name, Operator operator){
+        registeredOperators.put(name, operator);
+    }
+
+    /**
+     * Registers a number implementation under the given name.
+     * @param name the name of the number implementation.
+     * @param implementation the number implementation to register.
+     */
+    public void registerNumberImplementation(String name, NumberImplementation implementation){
+        registeredNumberImplementations.put(name, implementation);
+    }
+
+    /**
+     * Registers the given documentation with the plugin manager,
+     * making it accessible to the plugin manager etc.
+     * @param documentation the documentation to register.
+     */
+    public void registerDocumentation(Documentation documentation){
+        registeredDocumentation.add(documentation);
+    }
+
+    /**
+     * Gets the function registered under the given name.
+     * @param name the name of the function.
+     * @return the function, or null if it was not found.
+     */
+    public Function functionFor(String name){
+        return registeredFunctions.get(name);
+    }
+
+    /**
+     * Gets the operator registered under the given name.
+     * @param name the name of the operator.
+     * @return the operator, or null if it was not found.
+     */
+    public Operator operatorFor(String name){
+        return registeredOperators.get(name);
+    }
+
+    /**
+     * Gets the number implementation registered under the given name.
+     * @param name the name of the number implementation.
+     * @return the number implementation, or null if it was not found.
+     */
+    public NumberImplementation numberImplementationFor(String name){
+        return registeredNumberImplementations.get(name);
+    }
+
+    /**
+     * Gets the documentation for the given entity of the given type.
+     * @param name the name of the entity to search for.
+     * @param type the type that this entity is, to filter out similarly named documentation.
+     * @return the documentation object.
+     */
+    public Documentation documentationFor(String name, DocumentationType type){
+        Documentation toReturn = null;
+        for(Documentation entry : registeredDocumentation){
+            if(entry.getCodeName().equals(name) && entry.getType() == type) {
+                toReturn = entry;
                 break;
             }
         }
-
+        if(toReturn == null){
-        cache.put(name, loadedValue);
+            toReturn = new Documentation(name, "", "", "", type);
-        return loadedValue;
+            registerDocumentation(toReturn);
-    }
+        }
-
+        return toReturn;
-    /**
-     * Gets a function under the given name.
-     *
-     * @param name the name of the function
-     * @return the function under the given name.
-     */
-    public Function functionFor(String name) {
-        return searchCached(plugins, cachedFunctions, Plugin::providedFunctions, Plugin::getFunction, name);
-    }
-
-    /**
-     * Gets an operator under the given name.
-     *
-     * @param name the name of the operator.
-     * @return the operator under the given name.
-     */
-    public Operator operatorFor(String name) {
-        return searchCached(plugins, cachedOperators, Plugin::providedOperators, Plugin::getOperator, name);
-    }
-
-    /**
-     * Gets the number implementation under the given name.
-     *
-     * @param name the name of the implementation.
-     * @return the implementation.
-     */
-    public NumberImplementation numberImplementationFor(String name) {
-        return searchCached(plugins, cachedNumberImplementations, Plugin::providedNumberImplementations,
-                Plugin::getNumberImplementation, name);
     }
 
     /**
@@ -161,14 +170,11 @@ public class PluginManager {
     public NumberImplementation interfaceImplementationFor(Class<? extends NumberInterface> name) {
         if (cachedInterfaceImplementations.containsKey(name)) return cachedInterfaceImplementations.get(name);
         NumberImplementation toReturn = null;
-        outside:
+        for(String key : registeredNumberImplementations.keySet()){
-        for (Plugin plugin : plugins) {
+            NumberImplementation implementation = registeredNumberImplementations.get(key);
-            for (String implementationName : plugin.providedNumberImplementations()) {
+            if(implementation.getImplementation() == name) {
-                NumberImplementation implementation = plugin.getNumberImplementation(implementationName);
+                toReturn = implementation;
-                if (implementation.getImplementation().equals(name)) {
+                break;
-                    toReturn = implementation;
-                    break outside;
-                }
             }
         }
         cachedInterfaceImplementations.put(name, toReturn);
@@ -227,12 +233,6 @@ public class PluginManager {
             if (disabledPlugins.contains(plugin.getClass().getName())) continue;
             plugin.enable();
         }
-        for (Plugin plugin : plugins) {
-            if (disabledPlugins.contains(plugin.getClass().getName())) continue;
-            allFunctions.addAll(plugin.providedFunctions());
-            allOperators.addAll(plugin.providedOperators());
-            allNumberImplementations.addAll(plugin.providedNumberImplementations());
-        }
         listeners.forEach(e -> e.onLoad(this));
     }
 
@@ -246,14 +246,12 @@ public class PluginManager {
             if (disabledPlugins.contains(plugin.getClass().getName())) continue;
             plugin.disable();
         }
-        cachedFunctions.clear();
+        registeredFunctions.clear();
-        cachedOperators.clear();
+        registeredOperators.clear();
-        cachedNumberImplementations.clear();
+        registeredNumberImplementations.clear();
+        registeredDocumentation.clear();
         cachedInterfaceImplementations.clear();
         cachedPi.clear();
-        allFunctions.clear();
-        allOperators.clear();
-        allNumberImplementations.clear();
         listeners.forEach(e -> e.onUnload(this));
     }
 
@@ -271,7 +269,7 @@ public class PluginManager {
      * @return the set of all functions that were loaded.
      */
     public Set<String> getAllFunctions() {
-        return allFunctions;
+        return registeredFunctions.keySet();
     }
 
     /**
@@ -280,7 +278,7 @@ public class PluginManager {
      * @return the set of all operators that were loaded.
      */
     public Set<String> getAllOperators() {
-        return allOperators;
+        return registeredOperators.keySet();
     }
 
     /**
@@ -289,7 +287,7 @@ public class PluginManager {
      * @return the set of all implementations that were loaded.
      */
     public Set<String> getAllNumberImplementations() {
-        return allNumberImplementations;
+        return registeredNumberImplementations.keySet();
     }
 
     /**

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

@@ -1,15 +1,18 @@
 package org.nwapw.abacus.plugin;
 
-import org.nwapw.abacus.function.Function;
+import org.nwapw.abacus.function.*;
-import org.nwapw.abacus.function.Operator;
+import org.nwapw.abacus.lexing.pattern.Match;
-import org.nwapw.abacus.function.OperatorAssociativity;
-import org.nwapw.abacus.function.OperatorType;
 import org.nwapw.abacus.number.NaiveNumber;
 import org.nwapw.abacus.number.NumberInterface;
 import org.nwapw.abacus.number.PreciseNumber;
+import org.nwapw.abacus.parsing.Parser;
+import org.nwapw.abacus.parsing.ShuntingYardParser;
+import org.nwapw.abacus.tree.TokenType;
+import org.nwapw.abacus.tree.TreeNode;
 
 import java.util.ArrayList;
 import java.util.HashMap;
+import java.util.List;
 import java.util.function.BiFunction;
 
 /**
@@ -18,6 +21,11 @@ import java.util.function.BiFunction;
  */
 public class StandardPlugin extends Plugin {
 
+    /**
+     * Stores objects of NumberInterface with integer values for reuse.
+     */
+    private final static HashMap<Class<? extends NumberInterface>, HashMap<Integer, NumberInterface>> integerValues = new HashMap<>();
+
     /**
      * The addition operator, +
      */
@@ -112,7 +120,7 @@ public class StandardPlugin extends Plugin {
         @Override
         protected NumberInterface applyInternal(NumberInterface[] params) {
             if (params[0].signum() == 0) {
-                return (new NaiveNumber(1)).promoteTo(params[0].getClass());
+                return fromInt(params[0].getClass(), 1);
             }
             NumberInterface factorial = params[0];
             NumberInterface multiplier = params[0];
@@ -157,14 +165,14 @@ public class StandardPlugin extends Plugin {
             int powersOf2 = 0;
             while (FUNCTION_ABS.apply(param.subtract(NaiveNumber.ONE.promoteTo(param.getClass()))).compareTo(new NaiveNumber(0.1).promoteTo(param.getClass())) >= 0) {
                 if (param.subtract(NaiveNumber.ONE.promoteTo(param.getClass())).signum() == 1) {
-                    param = param.divide(new NaiveNumber(2).promoteTo(param.getClass()));
+                    param = param.divide(fromInt(param.getClass(), 2));
                     powersOf2++;
                     if (param.subtract(NaiveNumber.ONE.promoteTo(param.getClass())).signum() != 1) {
                         break;
                         //No infinite loop for you.
                     }
                 } else {
-                    param = param.multiply(new NaiveNumber(2).promoteTo(param.getClass()));
+                    param = param.multiply(fromInt(param.getClass(), 2));
                     powersOf2--;
                     if (param.subtract(NaiveNumber.ONE.promoteTo(param.getClass())).signum() != -1) {
                         break;
@@ -203,17 +211,17 @@ public class StandardPlugin extends Plugin {
          */
         private NumberInterface getLog2(NumberInterface number) {
             NumberInterface maxError = getMaxError(number);
-            //NumberInterface errorBound = (new NaiveNumber(1)).promoteTo(number.getClass());
+            //NumberInterface errorBound = fromInt(number.getClass(), 1);
             //We'll use the series \sigma_{n >= 1) ((1/3^n + 1/4^n) * 1/n)
             //In the following, a=1/3^n, b=1/4^n, c = 1/n.
             //a is also an error bound.
-            NumberInterface a = (new NaiveNumber(1)).promoteTo(number.getClass()), b = a, c = a;
+            NumberInterface a = fromInt(number.getClass(), 1), b = a, c = a;
             NumberInterface sum = NaiveNumber.ZERO.promoteTo(number.getClass());
             int n = 0;
             while (a.compareTo(maxError) >= 1) {
                 n++;
-                a = a.divide((new NaiveNumber(3)).promoteTo(number.getClass()));
+                a = a.divide(fromInt(number.getClass(), 3));
-                b = b.divide((new NaiveNumber(4)).promoteTo(number.getClass()));
+                b = b.divide(fromInt(number.getClass(), 4));
                 c = NaiveNumber.ONE.promoteTo(number.getClass()).divide((new NaiveNumber(n)).promoteTo(number.getClass()));
                 sum = sum.add(a.add(b).multiply(c));
             }
@@ -311,7 +319,7 @@ public class StandardPlugin extends Plugin {
                 //right and left refer to lhs and rhs in the above inequality.
                 NumberInterface sum = NaiveNumber.ONE.promoteTo(params[0].getClass());
                 NumberInterface nextNumerator = params[0];
-                NumberInterface left = params[0].multiply((new NaiveNumber(3)).promoteTo(params[0].getClass()).intPow(params[0].ceiling().intValue())), right = maxError;
+                NumberInterface left = params[0].multiply(fromInt(params[0].getClass(), 3).intPow(params[0].ceiling().intValue())), right = maxError;
                 do {
                     sum = sum.add(nextNumerator.divide(factorial(params[0].getClass(), n + 1)));
                     n++;
@@ -335,7 +343,8 @@ public class StandardPlugin extends Plugin {
         protected boolean matchesParams(NumberInterface[] params) {
             return params.length == 2
                     && !(params[0].compareTo(NaiveNumber.ZERO.promoteTo(params[0].getClass())) == 0
-                    && params[1].compareTo(NaiveNumber.ZERO.promoteTo(params[1].getClass())) == 0);
+                    && params[1].compareTo(NaiveNumber.ZERO.promoteTo(params[1].getClass())) == 0)
+                    && !(params[0].signum() == -1 && params[1].fractionalPart().compareTo(NaiveNumber.ZERO.promoteTo(params[1].getClass())) != 0);
         }
 
         @Override
@@ -344,6 +353,13 @@ public class StandardPlugin extends Plugin {
                 return NaiveNumber.ZERO.promoteTo(params[0].getClass());
             else if (params[1].compareTo(NaiveNumber.ZERO.promoteTo(params[0].getClass())) == 0)
                 return NaiveNumber.ONE.promoteTo(params[1].getClass());
+            //Detect integer bases:
+            if(params[0].fractionalPart().compareTo(fromInt(params[0].getClass(), 0)) == 0
+                    && FUNCTION_ABS.apply(params[0]).compareTo(fromInt(params[0].getClass(), Integer.MAX_VALUE)) < 0
+                    && FUNCTION_ABS.apply(params[1]).compareTo(fromInt(params[1].getClass(), 1)) >= 0){
+                NumberInterface[] newParams = {params[0], params[1].fractionalPart()};
+                return params[0].intPow(params[1].floor().intValue()).multiply(applyInternal(newParams));
+            }
             return FUNCTION_EXP.apply(FUNCTION_LN.apply(FUNCTION_ABS.apply(params[0])).multiply(params[1]));
         }
     });
@@ -358,13 +374,13 @@ public class StandardPlugin extends Plugin {
 
         @Override
         protected NumberInterface applyInternal(NumberInterface[] params) {
-            NumberInterface pi = getPi(params[0].getClass());
+            NumberInterface pi = piFor(params[0].getClass());
-            NumberInterface twoPi = pi.multiply(new NaiveNumber(2).promoteTo(pi.getClass()));
+            NumberInterface twoPi = pi.multiply(fromInt(pi.getClass(), 2));
             NumberInterface theta = getSmallAngle(params[0], pi);
             //System.out.println(theta);
             if (theta.compareTo(pi.multiply(new NaiveNumber(1.5).promoteTo(twoPi.getClass()))) >= 0) {
                 theta = theta.subtract(twoPi);
-            } else if (theta.compareTo(pi.divide(new NaiveNumber(2).promoteTo(pi.getClass()))) > 0) {
+            } else if (theta.compareTo(pi.divide(fromInt(pi.getClass(), 2))) > 0) {
                 theta = pi.subtract(theta);
             }
             //System.out.println(theta);
@@ -382,7 +398,7 @@ public class StandardPlugin extends Plugin {
 
         @Override
         protected NumberInterface applyInternal(NumberInterface[] params) {
-            return functionSin.apply(getPi(params[0].getClass()).divide(new NaiveNumber(2).promoteTo(params[0].getClass()))
+            return functionSin.apply(piFor(params[0].getClass()).divide(fromInt(params[0].getClass(), 2))
                     .subtract(params[0]));
         }
     };
@@ -470,7 +486,7 @@ public class StandardPlugin extends Plugin {
      * @return the maximum error.
      */
     private static NumberInterface getMaxError(NumberInterface number) {
-        return (new NaiveNumber(10)).promoteTo(number.getClass()).intPow(-number.getMaxPrecision());
+        return fromInt(number.getClass(), 10).intPow(-number.getMaxPrecision());
     }
 
     /**
@@ -531,6 +547,22 @@ public class StandardPlugin extends Plugin {
         return theta;
     }
 
+    /**
+     * Returns a number of class numType with value n.
+     * @param numType class of number to return.
+     * @param n value of returned number.
+     * @return numClass instance with value n.
+     */
+    private static NumberInterface fromInt(Class<? extends NumberInterface> numType, int n){
+        if(!integerValues.containsKey(numType)){
+            integerValues.put(numType, new HashMap<>());
+        }
+        if(!integerValues.get(numType).containsKey(n)){
+            integerValues.get(numType).put(n, new NaiveNumber(n).promoteTo(numType));
+        }
+        return integerValues.get(numType).get(n);
+    }
+
     @Override
     public void onEnable() {
         registerNumberImplementation("naive", IMPLEMENTATION_NAIVE);
@@ -554,6 +586,35 @@ public class StandardPlugin extends Plugin {
         registerFunction("sec", functionSec);
         registerFunction("csc", functionCsc);
         registerFunction("cot", functionCot);
+
+        registerDocumentation(new Documentation("abs", "Absolute Value", "Finds the distance " +
+                "from zero of a number.", "Given a number, this function finds the distance form " +
+                "zero of a number, effectively turning negative numbers into positive ones.\n\n" +
+                "Example: abs(-2) -> 2", DocumentationType.FUNCTION));
+        registerDocumentation(new Documentation("exp", "Exponentiate", "Brings e to the given power.",
+                "This function evaluates e to the power of the given value, and is the inverse " +
+                        "of the natural logarithm.\n\n" +
+                        "Example: exp(1) -> 2.718...", DocumentationType.FUNCTION));
+        registerDocumentation(new Documentation("ln", "Natural Logarithm", "Gets the natural " +
+                "logarithm of the given value.", "The natural logarithm of a number is " +
+                "the power that e has to be brought to to be equal to the number.\n\n" +
+                "Example: ln(2.718) -> 1", DocumentationType.FUNCTION));
+        registerDocumentation(new Documentation("sqrt", "Square Root", "Finds the square root " +
+                "of the number.", "A square root a of a number is defined such that a times a is equal " +
+                "to that number.\n\n" +
+                "Example: sqrt(4) -> 2", DocumentationType.FUNCTION));
+        registerDocumentation(new Documentation("sin", "Sine", "Computes the sine of the given angle, " +
+                "in radians.", "", DocumentationType.FUNCTION));
+        registerDocumentation(new Documentation("cos", "Cosine", "Computes the cosine of the given angle, " +
+                "in radians.", "", DocumentationType.FUNCTION));
+        registerDocumentation(new Documentation("tan", "Tangent", "Computes the tangent of the given angle, " +
+                "in radians.", "", DocumentationType.FUNCTION));
+        registerDocumentation(new Documentation("sec", "Secant", "Computes the secant of the given angle, " +
+                "in radians.", "", DocumentationType.FUNCTION));
+        registerDocumentation(new Documentation("csc", "Cosecant", "Computes the cosecant of the given angle, " +
+                "in radians.", "", DocumentationType.FUNCTION));
+        registerDocumentation(new Documentation("cot", "Cotangent", "Computes the cotangent of the given angle, " +
+                "in radians.", "", DocumentationType.FUNCTION));
     }
 
     @Override

src/main/java/org/nwapw/abacus/tree/BinaryNode.java

@@ -1,108 +0,0 @@
-package org.nwapw.abacus.tree;
-
-/**
- * A tree node that represents an operation being applied to two operands.
- */
-public class BinaryNode extends TreeNode {
-
-    /**
-     * The operation being applied.
-     */
-    private String operation;
-    /**
-     * The left node of the operation.
-     */
-    private TreeNode left;
-    /**
-     * The right node of the operation.
-     */
-    private TreeNode right;
-
-    private BinaryNode() {
-    }
-
-    /**
-     * Creates a new operation node with the given operation
-     * and no child nodes.
-     *
-     * @param operation the operation.
-     */
-    public BinaryNode(String operation) {
-        this(operation, null, null);
-    }
-
-    /**
-     * Creates a new operation node with the given operation
-     * and child nodes.
-     *
-     * @param operation the operation.
-     * @param left      the left node of the expression.
-     * @param right     the right node of the expression.
-     */
-    public BinaryNode(String operation, TreeNode left, TreeNode right) {
-        this.operation = operation;
-        this.left = left;
-        this.right = right;
-    }
-
-    /**
-     * Gets the operation in this node.
-     *
-     * @return the operation in this node.
-     */
-    public String getOperation() {
-        return operation;
-    }
-
-    /**
-     * Gets the left sub-expression of this node.
-     *
-     * @return the left node.
-     */
-    public TreeNode getLeft() {
-        return left;
-    }
-
-    /**
-     * Sets the left sub-expression of this node.
-     *
-     * @param left the sub-expression to apply.
-     */
-    public void setLeft(TreeNode left) {
-        this.left = left;
-    }
-
-    /**
-     * Gets the right sub-expression of this node.
-     *
-     * @return the right node.
-     */
-    public TreeNode getRight() {
-        return right;
-    }
-
-    /**
-     * Sets the right sub-expression of this node.
-     *
-     * @param right the sub-expression to apply.
-     */
-    public void setRight(TreeNode right) {
-        this.right = right;
-    }
-
-    @Override
-    public <T> T reduce(Reducer<T> reducer) {
-        T leftReduce = left.reduce(reducer);
-        T rightReduce = right.reduce(reducer);
-        if (leftReduce == null || rightReduce == null) return null;
-        return reducer.reduceNode(this, leftReduce, rightReduce);
-    }
-
-    @Override
-    public String toString() {
-        String leftString = left != null ? left.toString() : "null";
-        String rightString = right != null ? right.toString() : "null";
-
-        return "(" + leftString + operation + rightString + ")";
-    }
-}

src/main/java/org/nwapw/abacus/tree/FunctionNode.java

@@ -1,85 +0,0 @@
-package org.nwapw.abacus.tree;
-
-import java.util.ArrayList;
-import java.util.List;
-
-/**
- * A node that represents a function call.
- */
-public class FunctionNode extends TreeNode {
-
-    /**
-     * The name of the function being called
-     */
-    private String function;
-    /**
-     * The list of arguments to the function.
-     */
-    private List<TreeNode> children;
-
-    /**
-     * Creates a function node with no function.
-     */
-    private FunctionNode() {
-    }
-
-    /**
-     * Creates a new function node with the given function name.
-     *
-     * @param function the function name.
-     */
-    public FunctionNode(String function) {
-        this.function = function;
-        children = new ArrayList<>();
-    }
-
-    /**
-     * Gets the function name for this node.
-     *
-     * @return the function name.
-     */
-    public String getFunction() {
-        return function;
-    }
-
-    /**
-     * Adds a child to the end of this node's child list.
-     *
-     * @param node the child to add.
-     */
-    public void appendChild(TreeNode node) {
-        children.add(node);
-    }
-
-    /**
-     * Adds a new child to the beginning of this node's child list.
-     *
-     * @param node the node to add.
-     */
-    public void prependChild(TreeNode node) {
-        children.add(0, node);
-    }
-
-    @Override
-    public <T> T reduce(Reducer<T> reducer) {
-        Object[] reducedChildren = new Object[children.size()];
-        for (int i = 0; i < reducedChildren.length; i++) {
-            reducedChildren[i] = children.get(i).reduce(reducer);
-            if (reducedChildren[i] == null) return null;
-        }
-        return reducer.reduceNode(this, reducedChildren);
-    }
-
-    @Override
-    public String toString() {
-        StringBuilder buffer = new StringBuilder();
-        buffer.append(function);
-        buffer.append("(");
-        for (int i = 0; i < children.size(); i++) {
-            buffer.append(children.get(i));
-            buffer.append(i == children.size() - 1 ? "" : ", ");
-        }
-        buffer.append(")");
-        return buffer.toString();
-    }
-}

src/main/java/org/nwapw/abacus/tree/NumberNode.java

@@ -1,49 +0,0 @@
-package org.nwapw.abacus.tree;
-
-import org.nwapw.abacus.number.NumberInterface;
-
-/**
- * A node implementation that represents a single number.
- */
-public class NumberNode extends TreeNode {
-
-    /**
-     * The number that is represented by this number node.
-     */
-    private NumberInterface number;
-
-    /**
-     * Creates a number node with no number.
-     */
-    public NumberNode() {
-        number = null;
-    }
-
-    /**
-     * Creates a new number node with the given double value.
-     *
-     * @param newNumber the number for which to create a number node.
-     */
-    public NumberNode(NumberInterface newNumber) {
-        this.number = newNumber;
-    }
-
-    /**
-     * Gets the number value of this node.
-     *
-     * @return the number value of this node.
-     */
-    public NumberInterface getNumber() {
-        return number;
-    }
-
-    @Override
-    public <T> T reduce(Reducer<T> reducer) {
-        return reducer.reduceNode(this);
-    }
-
-    @Override
-    public String toString() {
-        return number != null ? number.toString() : "null";
-    }
-}

src/main/java/org/nwapw/abacus/tree/TreeNode.java

@@ -1,17 +0,0 @@
-package org.nwapw.abacus.tree;
-
-/**
- * An abstract class that represents an expression tree node.
- */
-public abstract class TreeNode {
-
-    /**
-     * The function that reduces a tree to a single vale.
-     *
-     * @param reducer the reducer used to reduce the tree.
-     * @param <T>     the type the reducer produces.
-     * @return the result of the reduction, or null on error.
-     */
-    public abstract <T> T reduce(Reducer<T> reducer);
-
-}

src/main/java/org/nwapw/abacus/tree/UnaryNode.java

@@ -1,63 +0,0 @@
-package org.nwapw.abacus.tree;
-
-public class UnaryNode extends TreeNode {
-
-    /**
-     * The operation this node will apply.
-     */
-    private String operation;
-    /**
-     * The tree node to apply the operation to.
-     */
-    private TreeNode applyTo;
-
-    /**
-     * Creates a new node with the given operation and no child.
-     *
-     * @param operation the operation for this node.
-     */
-    public UnaryNode(String operation) {
-        this(operation, null);
-    }
-
-    /**
-     * Creates a new node with the given operation and child.
-     *
-     * @param operation the operation for this node.
-     * @param applyTo   the node to apply the function to.
-     */
-    public UnaryNode(String operation, TreeNode applyTo) {
-        this.operation = operation;
-        this.applyTo = applyTo;
-    }
-
-    @Override
-    public <T> T reduce(Reducer<T> reducer) {
-        Object reducedChild = applyTo.reduce(reducer);
-        if (reducedChild == null) return null;
-        return reducer.reduceNode(this, reducedChild);
-    }
-
-    /**
-     * Gets the operation of this node.
-     *
-     * @return the operation this node performs.
-     */
-    public String getOperation() {
-        return operation;
-    }
-
-    /**
-     * Gets the node to which this node's operation applies.
-     *
-     * @return the tree node to which the operation will be applied.
-     */
-    public TreeNode getApplyTo() {
-        return applyTo;
-    }
-
-    @Override
-    public String toString() {
-        return "(" + (applyTo == null ? "null" : applyTo.toString()) + ")" + operation;
-    }
-}

src/main/kotlin/org/nwapw/abacus/function/Documentation.kt

@@ -0,0 +1,26 @@
+package org.nwapw.abacus.function
+
+/**
+ * A data class used for storing information about a function.
+ *
+ * The Documentation class holds the information necessary to display the information
+ * about a function to the user.
+ *
+ * @param codeName the name of the function as it occurs in code.
+ * @param name the name of the function in English.
+ * @param description the short description of this function.
+ * @param longDescription the full description of this function.
+ * @param type the things this documentation maps to.
+ */
+data class Documentation(val codeName: String, val name: String,
+                         val description: String, val longDescription: String,
+                         val type: DocumentationType) {
+
+    fun matches(other: String): Boolean {
+        return codeName.toLowerCase().contains(other.toLowerCase()) ||
+                name.toLowerCase().contains(other.toLowerCase()) ||
+                description.toLowerCase().contains(other.toLowerCase()) ||
+                longDescription.toLowerCase().contains(other.toLowerCase())
+    }
+
+}

src/main/kotlin/org/nwapw/abacus/function/Operator.kt

@@ -0,0 +1,14 @@
+package org.nwapw.abacus.function
+
+/**
+ * A single operator that can be used by Abacus.
+ *
+ * This is a data class that holds the information about a single operator, such as a plus or minus.
+ *
+ * @param associativity the associativity of this operator, used for order of operations;.
+ * @param type the type of this operator, used for parsing (infix / prefix / postfix and binary / unary)
+ * @param precedence the precedence of this operator, used for order of operations.
+ * @param function the function this operator applies to its arguments.
+ */
+data class Operator(val associativity: OperatorAssociativity, val type: OperatorType,
+                    val precedence: Int, val function: Function)

src/main/kotlin/org/nwapw/abacus/tree/BinaryNode.kt

@@ -0,0 +1,26 @@
+package org.nwapw.abacus.tree
+
+/**
+ * A tree node that holds a binary operation.
+ *
+ * This node represents any binary operation, such as binary infix or binary postfix. The only
+ * currently implemented into Abacus is binary infix, but that has more to do with the parser than
+ * this class, which doesn't care about the order that its operation and nodes were found in text.
+ *
+ * @param operation the operation this node performs on its children.
+ * @param left the left node.
+ * @param right the right node.
+ */
+data class BinaryNode(val operation: String, val left: TreeNode? = null, val right: TreeNode?) : TreeNode() {
+
+    override fun <T : Any> reduce(reducer: Reducer<T>): T? {
+        val leftReduce = left?.reduce(reducer) ?: return null
+        val rightReduce = right?.reduce(reducer) ?: return null
+        return reducer.reduceNode(this, leftReduce, rightReduce)
+    }
+
+    override fun toString(): String {
+        return "(" + (left?.toString() ?: "null") + operation + (right?.toString() ?: "null") + ")"
+    }
+
+}

src/main/kotlin/org/nwapw/abacus/tree/FunctionNode.kt

@@ -0,0 +1,52 @@
+package org.nwapw.abacus.tree
+
+/**
+ * A tree node that holds a function call.
+ *
+ * The function call node can hold any number of children, and passes the to the appropriate reducer,
+ * but that is its sole purpose.
+ *
+ * @param function the function string.
+ */
+data class FunctionNode(val function: String) : TreeNode() {
+
+    /**
+     * List of function parameters added to this node.
+     */
+    val children: MutableList<TreeNode> = mutableListOf()
+
+    override fun <T : Any> reduce(reducer: Reducer<T>): T? {
+        val children = Array<Any?>(children.size, { children[it].reduce(reducer) ?: return null; })
+        return reducer.reduceNode(this, *children)
+    }
+
+    override fun toString(): String {
+        val buffer = StringBuffer()
+        buffer.append(function)
+        buffer.append('(')
+        for (i in 0 until children.size) {
+            buffer.append(children[i].toString())
+            buffer.append(if (i == children.size - 1) ")" else ",")
+        }
+        return buffer.toString()
+    }
+
+    /**
+     * Appends a child to this node's list of children.
+     *
+     * @node the node to append.
+     */
+    fun appendChild(node: TreeNode){
+        children.add(node)
+    }
+
+    /**
+     * Prepends a child to this node's list of children.
+     *
+     * @node the node to prepend.
+     */
+    fun prependChild(node: TreeNode){
+        children.add(0, node)
+    }
+
+}

src/main/kotlin/org/nwapw/abacus/tree/NumberNode.kt

@@ -0,0 +1,23 @@
+package org.nwapw.abacus.tree
+
+import org.nwapw.abacus.number.NumberInterface
+
+/**
+ * A tree node that holds a single number value.
+ *
+ * This is a tree node that holds a single NumberInterface, which represents any number,
+ * and is not defined during compile time.
+ *
+ * @number the number value of this node.
+ */
+data class NumberNode(val number: NumberInterface) : TreeNode() {
+
+    override fun <T : Any> reduce(reducer: Reducer<T>): T? {
+        return reducer.reduceNode(this)
+    }
+
+    override fun toString(): String {
+        return number.toString()
+    }
+
+}

src/main/kotlin/org/nwapw/abacus/tree/TreeNode.kt

@@ -0,0 +1,10 @@
+package org.nwapw.abacus.tree
+
+/**
+ * A tree node.
+ */
+abstract class TreeNode {
+
+    abstract fun <T: Any> reduce(reducer: Reducer<T>) : T?
+
+}

src/main/kotlin/org/nwapw/abacus/tree/UnaryNode.kt

@@ -0,0 +1,23 @@
+package org.nwapw.abacus.tree
+
+/**
+ * A tree node that holds a unary operation.
+ *
+ * This node holds a single operator applied to a single parameter, and does not care
+ * whether the operation was found before or after the parameter in the text.
+ *
+ * @param operation the operation applied to the given node.
+ * @param applyTo the node to which the operation will be applied.
+ */
+data class UnaryNode(val operation: String, val applyTo: TreeNode? = null) : TreeNode() {
+
+    override fun <T : Any> reduce(reducer: Reducer<T>): T? {
+        val reducedChild = applyTo?.reduce(reducer) ?: return null
+        return reducer.reduceNode(this, reducedChild)
+    }
+
+    override fun toString(): String {
+        return "(" + (applyTo?.toString() ?: "null") + ")" + operation
+    }
+
+}

src/main/resources/abacus.fxml

@@ -60,6 +60,15 @@
                     </FlowPane>
                 </GridPane>
             </Tab>
+            <Tab fx:id="functionListTab" text="Functions" closable="false">
+                <VBox spacing="10">
+                    <padding>
+                        <Insets left="10" right="10" top="10" bottom="10"/>
+                    </padding>
+                    <TextField fx:id="functionListSearchField" maxWidth="Infinity"/>
+                    <ListView maxWidth="Infinity" fx:id="functionListView"/>
+                </VBox>
+            </Tab>
         </TabPane>
     </center>