Write arctan and add arccot.

This reverts commit f3942b6760.

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/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

@@ -5,6 +5,7 @@ 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.control.*;
 import javafx.scene.control.cell.CheckBoxListCell;
@@ -72,6 +73,8 @@ 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 +96,10 @@ public class AbacusController implements PluginListener {
     private ListView<ToggleablePlugin> enabledPluginView;
     @FXML
     private TextField computationLimitField;
+    @FXML
+    private ListView<String> functionListView;
+    @FXML
+    private TextField functionListSearchField;
 
     /**
      * The list of history entries, created by the users.
@@ -110,6 +117,14 @@ 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<String> functionList;
+    /**
+     * The filtered list displayed to the user.
+     */
+    private FilteredList<String> functionFilter;
 
     /**
      * The abacus instance used for changing the plugin configuration.
@@ -201,7 +216,7 @@ public class AbacusController implements PluginListener {
         Callback<TableColumn<HistoryModel, String>, TableCell<HistoryModel, String>> cellFactory =
                 param -> new CopyableCell<>();
         Callback<ListView<ToggleablePlugin>, ListCell<ToggleablePlugin>> pluginCellFactory =
-                param -> new CheckBoxListCell<>(ToggleablePlugin::enabledProperty, new StringConverter<ToggleablePlugin>() {
+                param -> new CheckBoxListCell<>(ToggleablePlugin::getEnabledProperty, new StringConverter<ToggleablePlugin>() {
                     @Override
                     public String toString(ToggleablePlugin object) {
                         return object.getClassName().substring(object.getClassName().lastIndexOf('.') + 1);
@@ -209,10 +224,15 @@ public class AbacusController implements PluginListener {
 
                     @Override
                     public ToggleablePlugin fromString(String string) {
-                        return new ToggleablePlugin(true, string);
+                        return new ToggleablePlugin(string, true);
                     }
                 });
 
+        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.contains(newValue))));
         historyData = FXCollections.observableArrayList();
         historyTable.setItems(historyData);
         numberImplementationOptions = FXCollections.observableArrayList();
@@ -223,11 +243,11 @@ public class AbacusController implements PluginListener {
         enabledPluginView.setItems(enabledPlugins);
         enabledPluginView.setCellFactory(pluginCellFactory);
         inputColumn.setCellFactory(cellFactory);
-        inputColumn.setCellValueFactory(cell -> cell.getValue().inputProperty());
+        inputColumn.setCellValueFactory(cell -> cell.getValue().getInputProperty());
         parsedColumn.setCellFactory(cellFactory);
-        parsedColumn.setCellValueFactory(cell -> cell.getValue().parsedProperty());
+        parsedColumn.setCellValueFactory(cell -> cell.getValue().getParsedProperty());
         outputColumn.setCellFactory(cellFactory);
-        outputColumn.setCellValueFactory(cell -> cell.getValue().outputProperty());
+        outputColumn.setCellValueFactory(cell -> cell.getValue().getOutputProperty());
         coreTabPane.getSelectionModel().selectedItemProperty().addListener((observable, oldValue, newValue) -> {
             if (oldValue.equals(settingsTab)) alertIfApplyNeeded(true);
         });
@@ -323,14 +343,17 @@ public class AbacusController implements PluginListener {
         numberImplementationBox.getSelectionModel().select(toSelect);
         for (Class<?> pluginClass : abacus.getPluginManager().getLoadedPluginClasses()) {
             String fullName = pluginClass.getName();
-            ToggleablePlugin plugin = new ToggleablePlugin(!disabledPlugins.contains(fullName), fullName);
+            ToggleablePlugin plugin = new ToggleablePlugin(fullName, !disabledPlugins.contains(fullName));
-            plugin.enabledProperty().addListener(e -> changesMade = true);
+            plugin.getEnabledProperty().addListener(e -> changesMade = true);
             enabledPlugins.add(plugin);
         }
+        functionList.addAll(manager.getAllFunctions());
+        functionList.sort(String::compareTo);
     }
 
     @Override
     public void onUnload(PluginManager manager) {
+        functionList.clear();
         enabledPlugins.clear();
         numberImplementationOptions.clear();
     }

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

@@ -1,97 +0,0 @@
-package org.nwapw.abacus.fx;
-
-import javafx.beans.property.SimpleStringProperty;
-import javafx.beans.property.StringProperty;
-
-/**
- * The data model used for storing history entries.
- */
-public class HistoryModel {
-
-    /**
-     * The property used for displaying the column
-     * for the user input.
-     */
-    private final StringProperty input;
-    /**
-     * The property used for displaying the column
-     * that contains the parsed input.
-     */
-    private final StringProperty parsed;
-    /**
-     * The property used for displaying the column
-     * that contains the program output.
-     */
-    private final StringProperty output;
-
-    /**
-     * Creates a new history model with the given variables.
-     *
-     * @param input  the user input
-     * @param parsed the parsed input
-     * @param output the program output.
-     */
-    public HistoryModel(String input, String parsed, String output) {
-        this.input = new SimpleStringProperty();
-        this.parsed = new SimpleStringProperty();
-        this.output = new SimpleStringProperty();
-        this.input.setValue(input);
-        this.parsed.setValue(parsed);
-        this.output.setValue(output);
-    }
-
-    /**
-     * Gets the input property.
-     *
-     * @return the input property.
-     */
-    public StringProperty inputProperty() {
-        return input;
-    }
-
-    /**
-     * Gets the input.
-     *
-     * @return the input.
-     */
-    public String getInput() {
-        return input.get();
-    }
-
-    /**
-     * Gets the parsed input property.
-     *
-     * @return the parsed input property.
-     */
-    public StringProperty parsedProperty() {
-        return parsed;
-    }
-
-    /**
-     * Gets the parsed input.
-     *
-     * @return the parsed input.
-     */
-    public String getParsed() {
-        return parsed.get();
-    }
-
-    /**
-     * Gets the output property.
-     *
-     * @return the output property.
-     */
-    public StringProperty outputProperty() {
-        return output;
-    }
-
-    /**
-     * Gets the program output.
-     *
-     * @return the output.
-     */
-    public String getOutput() {
-        return output.get();
-    }
-
-}

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

@@ -1,60 +0,0 @@
-package org.nwapw.abacus.fx;
-
-import javafx.beans.property.BooleanProperty;
-import javafx.beans.property.SimpleBooleanProperty;
-
-/**
- * Class that represents an entry in the plugin check box list.
- * The changes from this property are written to the config on application.
- */
-public class ToggleablePlugin {
-
-    /**
-     * The property that determines whether the plugin will be enabled.
-     */
-    private final BooleanProperty enabled;
-    /**
-     * The name of the class this entry toggles.
-     */
-    private final String className;
-
-    /**
-     * Creates a new toggleable plugin with the given properties.
-     *
-     * @param enabled   the enabled / disabled state at the beginning.
-     * @param className the name of the class this plugin toggles.
-     */
-    public ToggleablePlugin(boolean enabled, String className) {
-        this.enabled = new SimpleBooleanProperty();
-        this.enabled.setValue(enabled);
-        this.className = className;
-    }
-
-    /**
-     * Gets the enabled property of this plugin.
-     *
-     * @return the enabled property.
-     */
-    public BooleanProperty enabledProperty() {
-        return enabled;
-    }
-
-    /**
-     * Checks if this plugin entry should be enabled.
-     *
-     * @return whether this plugin will be enabled.
-     */
-    public boolean isEnabled() {
-        return enabled.get();
-    }
-
-    /**
-     * Gets the class name this plugin toggles.
-     *
-     * @return the class name that should be disabled.
-     */
-    public String getClassName() {
-        return className;
-    }
-
-}

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

@@ -209,6 +209,9 @@ public class PluginManager {
             if (disabledPlugins.contains(plugin.getClass().getName())) continue;
             plugin.disable();
         }
+        registeredFunctions.clear();
+        registeredOperators.clear();
+        registeredNumberImplementations.clear();
         cachedInterfaceImplementations.clear();
         cachedPi.clear();
         listeners.forEach(e -> e.onUnload(this));

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

@@ -451,6 +451,144 @@ public class StandardPlugin extends Plugin {
         }
     };
 
+    /**
+     * The arcsine function (return type in radians).
+     */
+    public final Function functionArcsin = new Function() {
+        @Override
+        protected boolean matchesParams(NumberInterface[] params) {
+            return params.length == 1
+                    && FUNCTION_ABS.apply(params[0]).compareTo(fromInt(params[0].getClass(), 1)) <= 0;
+        }
+
+        @Override
+        protected NumberInterface applyInternal(NumberInterface[] params) {
+            if(FUNCTION_ABS.apply(params[0]).compareTo(new NaiveNumber(0.8).promoteTo(params[0].getClass())) >= 0){
+                NumberInterface[] newParams = {FUNCTION_SQRT.apply(fromInt(params[0].getClass(), 1).subtract(params[0].multiply(params[0])))};
+                return piFor(params[0].getClass()).divide(fromInt(params[0].getClass(), 2))
+                        .subtract(applyInternal(newParams)).multiply(fromInt(params[0].getClass(), params[0].signum()));
+            }
+            NumberInterface currentTerm = params[0], sum = currentTerm,
+                    multiplier = currentTerm.multiply(currentTerm), summandBound = sum.getMaxError().multiply(fromInt(sum.getClass(), 1).subtract(multiplier)),
+                    power = currentTerm, coefficient = fromInt(params[0].getClass(), 1);
+            int exponent = 1;
+            while(FUNCTION_ABS.apply(currentTerm).compareTo(summandBound) > 0){
+                exponent += 2;
+                power = power.multiply(multiplier);
+                coefficient = coefficient.multiply(fromInt(params[0].getClass(), exponent-2))
+                        .divide(fromInt(params[0].getClass(), exponent - 1));
+                currentTerm = power.multiply(coefficient).divide(fromInt(power.getClass(), exponent));
+                sum = sum.add(currentTerm);
+            }
+            return sum;
+        }
+    };
+
+    /**
+     * The arccosine function.
+     */
+    public final Function functionArccos = new Function() {
+        @Override
+        protected boolean matchesParams(NumberInterface[] params) {
+            return params.length == 1 && FUNCTION_ABS.apply(params[0]).compareTo(fromInt(params[0].getClass(), 1)) <= 0;
+        }
+
+        @Override
+        protected NumberInterface applyInternal(NumberInterface[] params) {
+            return piFor(params[0].getClass()).divide(fromInt(params[0].getClass(), 2))
+                    .subtract(functionArcsin.apply(params));
+        }
+    };
+
+    /**
+     * The arccosecant function.
+     */
+    public final Function functionArccsc = new Function() {
+        @Override
+        protected boolean matchesParams(NumberInterface[] params) {
+            return params.length == 1 && FUNCTION_ABS.apply(params[0]).compareTo(fromInt(params[0].getClass(), 1)) >= 0;
+        }
+
+        @Override
+        protected NumberInterface applyInternal(NumberInterface[] params) {
+            NumberInterface[] reciprocalParamArr = {fromInt(params[0].getClass(), 1).divide(params[0])};
+            return functionArcsin.apply(reciprocalParamArr);
+        }
+    };
+
+    /**
+     * The arcsecant function.
+     */
+    public final Function functionArcsec = new Function() {
+        @Override
+        protected boolean matchesParams(NumberInterface[] params) {
+            return params.length == 1 && FUNCTION_ABS.apply(params[0]).compareTo(fromInt(params[0].getClass(), 1)) >= 0;
+        }
+
+        @Override
+        protected NumberInterface applyInternal(NumberInterface[] params) {
+            NumberInterface[] reciprocalParamArr = {fromInt(params[0].getClass(), 1).divide(params[0])};
+            return functionArccos.apply(reciprocalParamArr);
+        }
+    };
+
+    /**
+     * The arctangent function.
+     */
+    public final Function functionArctan = new Function() {
+        @Override
+        protected boolean matchesParams(NumberInterface[] params) {
+            return params.length == 1;
+        }
+
+        @Override
+        protected NumberInterface applyInternal(NumberInterface[] params) {
+            if(params[0].signum() == -1){
+                NumberInterface[] negatedParams = {params[0].negate()};
+                return applyInternal(negatedParams).negate();
+            }
+            if(params[0].compareTo(fromInt(params[0].getClass(), 1)) > 0){
+                NumberInterface[] reciprocalParams = {fromInt(params[0].getClass(), 1).divide(params[0])};
+                return piFor(params[0].getClass()).divide(fromInt(params[0].getClass(), 2))
+                        .subtract(applyInternal(reciprocalParams));
+            }
+            if(params[0].compareTo(fromInt(params[0].getClass(), 1)) == 0){
+                return piFor(params[0].getClass()).divide(fromInt(params[0].getClass(), 4));
+            }
+            if(params[0].compareTo(new NaiveNumber(0.9).promoteTo(params[0].getClass())) >= 0){
+                NumberInterface[] newParams = {params[0].multiply(fromInt(params[0].getClass(),2 ))
+                .divide(fromInt(params[0].getClass(), 1).subtract(params[0].multiply(params[0])))};
+                return applyInternal(newParams).divide(fromInt(params[0].getClass(), 2));
+            }
+            NumberInterface currentPower = params[0], currentTerm = currentPower, sum = currentTerm,
+                    maxError = params[0].getMaxError(), multiplier = currentPower.multiply(currentPower).negate();
+            int n = 1;
+            while(FUNCTION_ABS.apply(currentTerm).compareTo(maxError) > 0){
+                n += 2;
+                currentPower = currentPower.multiply(multiplier);
+                currentTerm = currentPower.divide(fromInt(currentPower.getClass(), n));
+                sum = sum.add(currentTerm);
+            }
+            return sum;
+        }
+    };
+
+    /**
+     * The arccotangent function. Range: (0, pi).
+     */
+    public final Function functionArccot = new Function() {
+        @Override
+        protected boolean matchesParams(NumberInterface[] params) {
+            return params.length == 1;
+        }
+
+        @Override
+        protected NumberInterface applyInternal(NumberInterface[] params) {
+            return piFor(params[0].getClass()).divide(fromInt(params[0].getClass(), 2))
+                    .subtract(functionArctan.apply(params));
+        }
+    };
+
     public StandardPlugin(PluginManager manager) {
         super(manager);
     }
@@ -568,6 +706,12 @@ public class StandardPlugin extends Plugin {
         registerFunction("sec", functionSec);
         registerFunction("csc", functionCsc);
         registerFunction("cot", functionCot);
+        registerFunction("arcsin", functionArcsin);
+        registerFunction("arccos", functionArccos);
+        registerFunction("arccsc", functionArccsc);
+        registerFunction("arcsec", functionArcsec);
+        registerFunction("arctan", functionArctan);
+        registerFunction("arccot", functionArccot);
     }
 
     @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/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/fx/HistoryModel.kt

@@ -0,0 +1,32 @@
+package org.nwapw.abacus.fx
+
+import javafx.beans.property.SimpleStringProperty
+
+/**
+ * A model representing an input / output in the calculator.
+ *
+ * The HistoryModel class stores a record of a single user-provided input,
+ * its parsed form as it was interpreted by the calculator, and the output
+ * that was provided by the calculator. These are represented as properties
+ * to allow easy access by JavaFX cells.
+ *
+ * @param input the user input
+ * @param parsed the parsed version of the input.
+ * @param output the output string.
+ */
+class HistoryModel(input: String, parsed: String, output: String){
+
+    /**
+     * The property that holds the input.
+     */
+    val inputProperty = SimpleStringProperty(input)
+    /**
+     * The property that holds the parsed input.
+     */
+    val parsedProperty = SimpleStringProperty(parsed)
+    /**
+     * The property that holds the output.
+     */
+    val outputProperty = SimpleStringProperty(output)
+
+}

src/main/kotlin/org/nwapw/abacus/fx/ToggleablePlugin.kt

@@ -0,0 +1,31 @@
+package org.nwapw.abacus.fx
+
+import javafx.beans.property.SimpleBooleanProperty
+
+/**
+ * A model representing a plugin that can be disabled or enabled.
+ *
+ * ToggleablePlugin is a model that is used to present to the user the option
+ * of disabling / enabling plugins. The class name in this plugin is stored if
+ * its "enabledPropery" is false, essentially blacklisting the plugin.
+ *
+ * @param className the name of the class that this model concerns.
+ * @param enabled whether or not the model should start enabled.
+ */
+class ToggleablePlugin (val className: String, enabled: Boolean) {
+
+    /**
+     * The property used to interact with JavaFX components.
+     */
+    val enabledProperty = SimpleBooleanProperty(enabled)
+
+    /**
+     * Checks whether this plugin is currently enabled or not.
+     *
+     * @return true if it is enabled, false otherwise.
+     */
+    fun isEnabled(): Boolean {
+        return enabledProperty.value
+    }
+
+}

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>