add stop on node

src/main/java/org/nwapw/abacus/Abacus.java

@@ -1,7 +1,6 @@
 package org.nwapw.abacus;
 
-import org.nwapw.abacus.config.Configuration;
-import org.nwapw.abacus.fx.AbacusApplication;
+import org.nwapw.abacus.config.ConfigurationObject;
 import org.nwapw.abacus.number.NaiveNumber;
 import org.nwapw.abacus.number.NumberInterface;
 import org.nwapw.abacus.parsing.LexerTokenizer;
@@ -12,7 +11,9 @@ import org.nwapw.abacus.plugin.PluginManager;
 import org.nwapw.abacus.plugin.StandardPlugin;
 import org.nwapw.abacus.tree.NumberReducer;
 import org.nwapw.abacus.tree.TreeNode;
+import org.nwapw.abacus.window.Window;
 
+import javax.swing.*;
 import java.io.File;
 import java.io.IOException;
 import java.lang.reflect.InvocationTargetException;
@@ -46,21 +47,24 @@ public class Abacus {
     /**
      * The configuration loaded from a file.
      */
-    private Configuration configuration;
+    private ConfigurationObject configuration;
     /**
      * The tree builder used to construct a tree
      * from a string.
      */
     private TreeBuilder treeBuilder;
-
+    private Window window;
+    public boolean getStop(){
+        return window.getStop();
+    }
     /**
      * Creates a new instance of the Abacus calculator.
      */
     public Abacus() {
-        pluginManager = new PluginManager(this);
+        pluginManager = new PluginManager();
         numberReducer = new NumberReducer(this);
-        configuration = new Configuration(CONFIG_FILE);
-        configuration.saveTo(CONFIG_FILE);
+        configuration = new ConfigurationObject(CONFIG_FILE);
+        configuration.save(CONFIG_FILE);
         LexerTokenizer lexerTokenizer = new LexerTokenizer();
         ShuntingYardParser shuntingYardParser = new ShuntingYardParser(this);
         treeBuilder = new TreeBuilder<>(lexerTokenizer, shuntingYardParser);
@@ -78,7 +82,13 @@ public class Abacus {
     }
 
     public static void main(String[] args) {
-        AbacusApplication.launch(AbacusApplication.class, args);
+        try {
+            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
+        } catch (ClassNotFoundException | InstantiationException | UnsupportedLookAndFeelException | IllegalAccessException e) {
+            e.printStackTrace();
+        }
+
+        new Window(new Abacus()).setVisible(true);
     }
 
     /**
@@ -114,7 +124,7 @@ public class Abacus {
      *
      * @return the configuration object.
      */
-    public Configuration getConfiguration() {
+    public ConfigurationObject getConfiguration() {
         return configuration;
     }
 
@@ -126,7 +136,7 @@ public class Abacus {
      * @return the resulting tree, null if the tree builder or the produced tree are null.
      */
     public TreeNode parseString(String input) {
-        return treeBuilder.fromString(input);
+        return treeBuilder.fromString(input,this);
     }
 
     /**
@@ -158,4 +168,8 @@ public class Abacus {
         }
         return null;
     }
+
+    public void setWindow(Window window) {
+        this.window = window;
+    }
 }

src/main/java/org/nwapw/abacus/config/Configuration.java

@@ -1,108 +1,14 @@
 package org.nwapw.abacus.config;
 
-import com.moandjiezana.toml.Toml;
-import com.moandjiezana.toml.TomlWriter;
-
-import java.io.File;
-import java.io.IOException;
-import java.util.Arrays;
-import java.util.HashSet;
-import java.util.Set;
-
 /**
- * The configuration object that stores
- * options that the user can change.
+ * Serializable class that will be used to load TOML
+ * configurations.
  */
 public class Configuration {
 
     /**
-     * The defaults TOML string.
+     * The type of number this calculator should use.
      */
-    private static final String DEFAULT_CONFIG =
-            "numberImplementation = \"naive\"\n" +
-            "disabledPlugins = []";
-    /**
-     * The defaults TOML object, parsed from the string.
-     */
-    private static final Toml DEFAULT_TOML = new Toml().read(DEFAULT_CONFIG);
-    /**
-     * The TOML writer used to write this configuration to a file.
-     */
-    private static final TomlWriter TOML_WRITER = new TomlWriter();
-
-    /**
-     * The implementation of the number that should be used.
-     */
-    private String numberImplementation = "<default>";
-    /**
-     * The list of disabled plugins in this Configuration.
-     */
-    private Set<String> disabledPlugins = new HashSet<>();
-
-    /**
-     * Creates a new configuration with the given values.
-     * @param numberImplementation the number implementation, like "naive" or "precise"
-     * @param disabledPlugins the list of disabled plugins.
-     */
-    public Configuration(String numberImplementation, String[] disabledPlugins){
-        this.numberImplementation = numberImplementation;
-        this.disabledPlugins.addAll(Arrays.asList(disabledPlugins));
-    }
-
-    /**
-     * Loads a configuration from a given file, keeping non-specified fields default.
-     * @param fromFile the file to load from.
-     */
-    public Configuration(File fromFile){
-        if(!fromFile.exists()) return;
-        copyFrom(new Toml(DEFAULT_TOML).read(fromFile).to(Configuration.class));
-    }
-
-    /**
-     * Copies the values from the given configuration into this one.
-     * @param otherConfiguration the configuration to copy from.
-     */
-    public void copyFrom(Configuration otherConfiguration){
-        this.numberImplementation = otherConfiguration.numberImplementation;
-        this.disabledPlugins.addAll(otherConfiguration.disabledPlugins);
-    }
-
-    /**
-     * Saves this configuration to the given file, creating
-     * any directories that do not exist.
-     * @param file the file to save to.
-     */
-    public void saveTo(File file){
-        if(file.getParentFile() != null) file.getParentFile().mkdirs();
-        try {
-            TOML_WRITER.write(this, file);
-        } catch (IOException e) {
-            e.printStackTrace();
-        }
-    }
-
-    /**
-     * Gets the number implementation from this configuration.
-     * @return the number implementation.
-     */
-    public String getNumberImplementation() {
-        return numberImplementation;
-    }
-
-    /**
-     * Sets the number implementation for the configuration
-     * @param numberImplementation the number implementation.
-     */
-    public void setNumberImplementation(String numberImplementation) {
-        this.numberImplementation = numberImplementation;
-    }
-
-    /**
-     * Gets the list of disabled plugins.
-     * @return the list of disabled plugins.
-     */
-    public Set<String> getDisabledPlugins() {
-        return disabledPlugins;
-    }
+    public String numberType;
 
 }

src/main/java/org/nwapw/abacus/config/ConfigurationObject.java

@@ -0,0 +1,111 @@
+package org.nwapw.abacus.config;
+
+import com.moandjiezana.toml.Toml;
+import com.moandjiezana.toml.TomlWriter;
+
+import java.io.File;
+import java.io.IOException;
+
+/**
+ * A configuration object, which essentially
+ * manages saving, loading, and getting values
+ * from the configuration. While Configuration is
+ * the data model, this is the interface with it.
+ */
+public class ConfigurationObject {
+
+    /**
+     * The writer used to store the configuration.
+     */
+    private static final TomlWriter TOML_WRITER = new TomlWriter();
+    /**
+     * The configuration instance being modeled.
+     */
+    private Configuration configuration;
+
+    /**
+     * Creates a new configuration object with the given config.
+     *
+     * @param config the config to use.
+     */
+    public ConfigurationObject(Configuration config) {
+        setup(config);
+    }
+
+    /**
+     * Create a configuration object by attempting to
+     * load a config from the given path, using the
+     * default configuration otherwise.
+     *
+     * @param path the path to attempt to load.
+     */
+    public ConfigurationObject(File path) {
+        Configuration config;
+        if (!path.exists()) {
+            config = getDefaultConfig();
+        } else {
+            Toml parse = new Toml();
+            parse.read(path);
+            config = parse.to(Configuration.class);
+        }
+        setup(config);
+    }
+
+    /**
+     * Creates a new configuration object with the
+     * default configuration.
+     */
+    public ConfigurationObject() {
+        setup(getDefaultConfig());
+    }
+
+    /**
+     * Sets up the ConfigurationObject.
+     * different constructors do different things,
+     * but they all lead here.
+     *
+     * @param configuration the configuration to set up with.
+     */
+    private void setup(Configuration configuration) {
+        this.configuration = configuration;
+    }
+
+    /**
+     * Creates a default configuration.
+     *
+     * @return the newly created default configuration.
+     */
+    private Configuration getDefaultConfig() {
+        configuration = new Configuration();
+        configuration.numberType = "naive";
+        return configuration;
+    }
+
+    /**
+     * Returns the implementation the user has requested to
+     * represent their numbers.
+     *
+     * @return the implementation name.
+     */
+    public String getNumberImplementation() {
+        return configuration.numberType;
+    }
+
+    /**
+     * Saves the ConfigurationObject to the given file.
+     *
+     * @param toFile the file to save ot.
+     * @return true if the save succeed, false if otherwise.
+     */
+    public boolean save(File toFile) {
+        if (toFile.getParentFile() != null) toFile.getParentFile().mkdirs();
+        try {
+            TOML_WRITER.write(configuration, toFile);
+            return true;
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+        return false;
+    }
+
+}

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

@@ -4,5 +4,5 @@ package org.nwapw.abacus.function;
  * The type of an operator, describing how it should behave.
  */
 public enum OperatorType {
-    BINARY_INFIX, UNARY_POSTFIX, UNARY_PREFIX
+    BINARY_INFIX, UNARY_POSTFIX
 }

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

@@ -1,24 +0,0 @@
-package org.nwapw.abacus.fx;
-
-import javafx.application.Application;
-import javafx.fxml.FXMLLoader;
-import javafx.scene.Parent;
-import javafx.scene.Scene;
-import javafx.stage.Stage;
-
-/**
- * The main application class for JavaFX responsible for loading
- * and displaying the fxml file.
- */
-public class AbacusApplication extends Application {
-
-    @Override
-    public void start(Stage primaryStage) throws Exception {
-        Parent parent = FXMLLoader.load(getClass().getResource("/abacus.fxml"));
-        Scene mainScene = new Scene(parent, 320, 480);
-        primaryStage.setScene(mainScene);
-        primaryStage.setTitle("Abacus");
-        primaryStage.show();
-    }
-
-}

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

@@ -1,170 +0,0 @@
-package org.nwapw.abacus.fx;
-
-import javafx.collections.FXCollections;
-import javafx.collections.ObservableList;
-import javafx.fxml.FXML;
-import javafx.scene.control.*;
-import javafx.scene.control.cell.CheckBoxListCell;
-import javafx.scene.text.Text;
-import javafx.util.Callback;
-import javafx.util.StringConverter;
-import org.nwapw.abacus.Abacus;
-import org.nwapw.abacus.config.Configuration;
-import org.nwapw.abacus.number.NumberInterface;
-import org.nwapw.abacus.plugin.PluginListener;
-import org.nwapw.abacus.plugin.PluginManager;
-import org.nwapw.abacus.tree.TreeNode;
-
-import java.util.Set;
-
-
-/**
- * The controller for the abacus FX UI, responsible
- * for all the user interaction.
- */
-public class AbacusController implements PluginListener {
-
-    /**
-     * Constant string that is displayed if the text could not be lexed or parsed.
-     */
-    private static final String ERR_SYNTAX = "Syntax Error";
-    /**
-     * Constant string that is displayed if the tree could not be reduced.
-     */
-    private static final String ERR_EVAL = "Evaluation Error";
-
-    @FXML
-    private TableView<HistoryModel> historyTable;
-    @FXML
-    private TableColumn<HistoryModel, String> inputColumn;
-    @FXML
-    private TableColumn<HistoryModel, String> parsedColumn;
-    @FXML
-    private TableColumn<HistoryModel, String> outputColumn;
-    @FXML
-    private Text outputText;
-    @FXML
-    private TextField inputField;
-    @FXML
-    private Button inputButton;
-    @FXML
-    private ComboBox<String> numberImplementationBox;
-    @FXML
-    private ListView<ToggleablePlugin> enabledPluginView;
-
-    /**
-     * The list of history entries, created by the users.
-     */
-    private ObservableList<HistoryModel> historyData;
-
-    /**
-     * The abacus instance used for calculations and all
-     * other main processing code.
-     */
-    private ObservableList<String> numberImplementationOptions;
-
-    /**
-     * The list of plugin objects that can be toggled on and off,
-     * and, when reloaded, get added to the plugin manager's black list.
-     */
-    private ObservableList<ToggleablePlugin> enabledPlugins;
-
-    private Abacus abacus;
-
-    @FXML
-    public void initialize(){
-        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>() {
-                    @Override
-                    public String toString(ToggleablePlugin object) {
-                        return object.getClassName().substring(object.getClassName().lastIndexOf('.') + 1);
-                    }
-
-                    @Override
-                    public ToggleablePlugin fromString(String string) {
-                        return new ToggleablePlugin(true, string);
-                    }
-                });
-
-        historyData = FXCollections.observableArrayList();
-        historyTable.setItems(historyData);
-        numberImplementationOptions = FXCollections.observableArrayList();
-        numberImplementationBox.setItems(numberImplementationOptions);
-        historyTable.getSelectionModel().setCellSelectionEnabled(true);
-        enabledPlugins = FXCollections.observableArrayList();
-        enabledPluginView.setItems(enabledPlugins);
-        enabledPluginView.setCellFactory(pluginCellFactory);
-        inputColumn.setCellFactory(cellFactory);
-        inputColumn.setCellValueFactory(cell -> cell.getValue().inputProperty());
-        parsedColumn.setCellFactory(cellFactory);
-        parsedColumn.setCellValueFactory(cell -> cell.getValue().parsedProperty());
-        outputColumn.setCellFactory(cellFactory);
-        outputColumn.setCellValueFactory(cell -> cell.getValue().outputProperty());
-
-        abacus = new Abacus();
-        abacus.getPluginManager().addListener(this);
-        abacus.getPluginManager().reload();
-    }
-
-    @FXML
-    private void performCalculation(){
-        inputButton.setDisable(true);
-        TreeNode constructedTree = abacus.parseString(inputField.getText());
-        if(constructedTree == null){
-            outputText.setText(ERR_SYNTAX);
-            inputButton.setDisable(false);
-            return;
-        }
-        NumberInterface evaluatedNumber = abacus.evaluateTree(constructedTree);
-        if(evaluatedNumber == null){
-            outputText.setText(ERR_EVAL);
-            inputButton.setDisable(false);
-            return;
-        }
-        outputText.setText(evaluatedNumber.toString());
-        historyData.add(new HistoryModel(inputField.getText(), constructedTree.toString(), evaluatedNumber.toString()));
-
-        inputButton.setDisable(false);
-        inputField.setText("");
-    }
-
-    @FXML
-    private void performReload(){
-        Configuration configuration = abacus.getConfiguration();
-        Set<String> disabledPlugins = configuration.getDisabledPlugins();
-        disabledPlugins.clear();
-        for(ToggleablePlugin pluginEntry : enabledPlugins){
-            if(!pluginEntry.isEnabled()) disabledPlugins.add(pluginEntry.getClassName());
-        }
-        abacus.getPluginManager().reload();
-    }
-
-    @FXML
-    private void performSave(){
-        Configuration configuration = abacus.getConfiguration();
-        configuration.setNumberImplementation(numberImplementationBox.getSelectionModel().getSelectedItem());
-        configuration.saveTo(Abacus.CONFIG_FILE);
-    }
-
-    @Override
-    public void onLoad(PluginManager manager) {
-        Configuration configuration = abacus.getConfiguration();
-        Set<String> disabledPlugins = configuration.getDisabledPlugins();
-        numberImplementationOptions.addAll(abacus.getPluginManager().getAllNumbers());
-        String actualImplementation = configuration.getNumberImplementation();
-        String toSelect = (numberImplementationOptions.contains(actualImplementation)) ? actualImplementation : "<default>";
-        numberImplementationBox.getSelectionModel().select(toSelect);
-        for(Class<?> pluginClass : abacus.getPluginManager().getLoadedPluginClasses()){
-            String fullName = pluginClass.getName();
-            enabledPlugins.add(new ToggleablePlugin(!disabledPlugins.contains(fullName), fullName));
-        }
-    }
-
-    @Override
-    public void onUnload(PluginManager manager) {
-        enabledPlugins.clear();
-        numberImplementationOptions.clear();
-    }
-}

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

@@ -1,35 +0,0 @@
-package org.nwapw.abacus.fx;
-
-import javafx.scene.control.TableCell;
-import javafx.scene.input.MouseEvent;
-
-import java.awt.*;
-import java.awt.datatransfer.StringSelection;
-
-/**
- * A cell that copies its value to the clipboard
- * when double clicked.
- * @param <S> The type of the table view generic type.
- * @param <T> The type of the value contained in the cell.
- */
-public class CopyableCell<S, T> extends TableCell<S, T> {
-
-    /**
-     * Creates a new copyable cell.
-     */
-    public CopyableCell(){
-        addEventFilter(MouseEvent.MOUSE_CLICKED, event -> {
-            if(event.getClickCount() == 2){
-                Toolkit.getDefaultToolkit().getSystemClipboard()
-                        .setContents(new StringSelection(getText()), null);
-            }
-        });
-    }
-
-    @Override
-    protected void updateItem(T item, boolean empty) {
-        super.updateItem(item, empty);
-        setText((empty || item == null) ? null : item.toString());
-        setGraphic(null);
-    }
-}

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

@@ -1,87 +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

@@ -1,29 +0,0 @@
-package org.nwapw.abacus.fx;
-
-import javafx.beans.property.BooleanProperty;
-import javafx.beans.property.SimpleBooleanProperty;
-
-public class ToggleablePlugin {
-
-    private final BooleanProperty enabled;
-    private final String className;
-
-    public ToggleablePlugin(boolean enabled, String className){
-        this.enabled = new SimpleBooleanProperty();
-        this.enabled.setValue(enabled);
-        this.className = className;
-    }
-
-    public BooleanProperty enabledProperty() {
-        return enabled;
-    }
-
-    public boolean isEnabled() {
-        return enabled.get();
-    }
-
-    public String getClassName() {
-        return className;
-    }
-
-}

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

@@ -93,11 +93,6 @@ public class NaiveNumber implements NumberInterface {
         return this.compareTo(ZERO);
     }
 
-    @Override
-    public int ceiling() {
-        return (int) Math.ceil(value);
-    }
-
     @Override
     public NumberInterface promoteTo(Class<? extends NumberInterface> toClass) {
         if (toClass == this.getClass()) return this;

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

@@ -79,12 +79,6 @@ public interface NumberInterface {
      */
     int signum();
 
-    /**
-     * Returns the least integer greater than or equal to the number.
-     * @return the least integer >= the number, if int can hold the value.
-     */
-    int ceiling();
-
     /**
      * Promotes this class to another number class.
      *

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

@@ -3,10 +3,6 @@ package org.nwapw.abacus.number;
 import java.math.BigDecimal;
 import java.math.RoundingMode;
 
-/**
- * A number that uses a BigDecimal to store its value,
- * leading to infinite possible precision.
- */
 public class PreciseNumber implements NumberInterface {
 
     /**
@@ -48,12 +44,12 @@ public class PreciseNumber implements NumberInterface {
 
     @Override
     public int getMaxPrecision() {
-        return 65;
+        return 54;
     }
 
     @Override
     public NumberInterface multiply(NumberInterface multiplier) {
-        return new PreciseNumber(this.value.multiply(((PreciseNumber) multiplier).value));
+        return new PreciseNumber(value.multiply(((PreciseNumber) multiplier).value));
     }
 
     @Override
@@ -98,11 +94,6 @@ public class PreciseNumber implements NumberInterface {
         return value.signum();
     }
 
-    @Override
-    public int ceiling() {
-        return (int) Math.ceil(value.doubleValue());
-    }
-
     @Override
     public NumberInterface negate() {
         return new PreciseNumber(value.negate());
@@ -118,7 +109,7 @@ public class PreciseNumber implements NumberInterface {
 
     @Override
     public String toString() {
-        BigDecimal rounded = value.setScale(getMaxPrecision() - 15, RoundingMode.HALF_UP);
+        BigDecimal rounded = value.setScale(getMaxPrecision() - 4, RoundingMode.HALF_UP);
         return rounded.stripTrailingZeros().toPlainString();
     }
 }

src/main/java/org/nwapw/abacus/parsing/Parser.java

@@ -1,5 +1,6 @@
 package org.nwapw.abacus.parsing;
 
+import org.nwapw.abacus.Abacus;
 import org.nwapw.abacus.tree.TreeNode;
 
 import java.util.List;
@@ -18,5 +19,5 @@ public interface Parser<T> {
      * @param tokens the tokens to construct a tree from.
      * @return the constructed tree, or null on error.
      */
-    public TreeNode constructTree(List<T> tokens);
+    public TreeNode constructTree(List<T> tokens,Abacus trace);
 }

src/main/java/org/nwapw/abacus/parsing/ShuntingYardParser.java

@@ -34,6 +34,8 @@ public class ShuntingYardParser implements Parser<Match<TokenType>>, PluginListe
      */
     private Map<String, OperatorType> typeMap;
 
+    //private Abacus trace;
+
     /**
      * Creates a new Shunting Yard parser with the given Abacus instance.
      *
@@ -55,12 +57,9 @@ public class ShuntingYardParser implements Parser<Match<TokenType>>, PluginListe
     public List<Match<TokenType>> intoPostfix(List<Match<TokenType>> from) {
         ArrayList<Match<TokenType>> output = new ArrayList<>();
         Stack<Match<TokenType>> tokenStack = new Stack<>();
-        TokenType previousType;
-        TokenType matchType = null;
         while (!from.isEmpty()) {
             Match<TokenType> match = from.remove(0);
-            previousType = matchType;
-            matchType = match.getType();
+            TokenType matchType = match.getType();
             if (matchType == TokenType.NUM) {
                 output.add(match);
             } else if (matchType == TokenType.FUNCTION) {
@@ -77,13 +76,7 @@ public class ShuntingYardParser implements Parser<Match<TokenType>>, PluginListe
                     continue;
                 }
 
-                if(tokenString.equals("-") && (previousType == null || previousType == TokenType.OP ||
-                        previousType == TokenType.OPEN_PARENTH)){
-                    from.add(0, new Match<>("`", TokenType.OP));
-                    continue;
-                }
-
-                while (!tokenStack.empty() && type == OperatorType.BINARY_INFIX) {
+                while (!tokenStack.empty()) {
                     Match<TokenType> otherMatch = tokenStack.peek();
                     TokenType otherMatchType = otherMatch.getType();
                     if (!(otherMatchType == TokenType.OP || otherMatchType == TokenType.FUNCTION)) break;
@@ -112,8 +105,8 @@ public class ShuntingYardParser implements Parser<Match<TokenType>>, PluginListe
         }
         while (!tokenStack.empty()) {
             Match<TokenType> match = tokenStack.peek();
-            TokenType newMatchType = match.getType();
-            if (!(newMatchType == TokenType.OP || newMatchType == TokenType.FUNCTION)) return null;
+            TokenType matchType = match.getType();
+            if (!(matchType == TokenType.OP || matchType == TokenType.FUNCTION)) return null;
             output.add(tokenStack.pop());
         }
         return output;
@@ -125,7 +118,8 @@ public class ShuntingYardParser implements Parser<Match<TokenType>>, PluginListe
      * @param matches the list of tokens from the source string.
      * @return the construct tree expression.
      */
-    public TreeNode constructRecursive(List<Match<TokenType>> matches) {
+    public TreeNode constructRecursive(List<Match<TokenType>> matches,Abacus trace) {
+        //this.trace = trace;
         if (matches.size() == 0) return null;
         Match<TokenType> match = matches.remove(0);
         TokenType matchType = match.getType();
@@ -133,22 +127,22 @@ public class ShuntingYardParser implements Parser<Match<TokenType>>, PluginListe
             String operator = match.getContent();
             OperatorType type = typeMap.get(operator);
             if (type == OperatorType.BINARY_INFIX) {
-                TreeNode right = constructRecursive(matches);
-                TreeNode left = constructRecursive(matches);
+                TreeNode right = constructRecursive(matches,trace);
+                TreeNode left = constructRecursive(matches,trace);
                 if (left == null || right == null) return null;
-                else return new BinaryNode(operator, left, right);
+                else return new BinaryInfixNode(operator, left, right,trace);
             } else {
-                TreeNode applyTo = constructRecursive(matches);
+                TreeNode applyTo = constructRecursive(matches,trace);
                 if (applyTo == null) return null;
-                else return new UnaryNode(operator, applyTo);
+                else return new UnaryPrefixNode(operator, applyTo,trace);
             }
         } else if (matchType == TokenType.NUM) {
             return new NumberNode(abacus.numberFromString(match.getContent()));
         } else if (matchType == TokenType.FUNCTION) {
             String functionName = match.getContent();
-            FunctionNode node = new FunctionNode(functionName);
+            FunctionNode node = new FunctionNode(functionName,trace);
             while (!matches.isEmpty() && matches.get(0).getType() != TokenType.INTERNAL_FUNCTION_END) {
-                TreeNode argument = constructRecursive(matches);
+                TreeNode argument = constructRecursive(matches,trace);
                 if (argument == null) return null;
                 node.prependChild(argument);
             }
@@ -160,10 +154,10 @@ public class ShuntingYardParser implements Parser<Match<TokenType>>, PluginListe
     }
 
     @Override
-    public TreeNode constructTree(List<Match<TokenType>> tokens) {
+    public TreeNode constructTree(List<Match<TokenType>> tokens,Abacus trace) {
         tokens = intoPostfix(new ArrayList<>(tokens));
         Collections.reverse(tokens);
-        return constructRecursive(tokens);
+        return constructRecursive(tokens,trace);
     }
 
     @Override

src/main/java/org/nwapw/abacus/parsing/TreeBuilder.java

@@ -1,5 +1,6 @@
 package org.nwapw.abacus.parsing;
 
+import org.nwapw.abacus.Abacus;
 import org.nwapw.abacus.tree.TreeNode;
 
 import java.util.List;
@@ -41,10 +42,10 @@ public class TreeBuilder<T> {
      * @param input the string to parse into a tree.
      * @return the resulting tree.
      */
-    public TreeNode fromString(String input) {
+    public TreeNode fromString(String input,Abacus trace) {
         List<T> tokens = tokenizer.tokenizeString(input);
         if (tokens == null) return null;
-        return parser.constructTree(tokens);
+        return parser.constructTree(tokens,trace);
     }
 
 }

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

@@ -1,6 +1,5 @@
 package org.nwapw.abacus.plugin;
 
-import org.nwapw.abacus.Abacus;
 import org.nwapw.abacus.function.Function;
 import org.nwapw.abacus.function.Operator;
 import org.nwapw.abacus.number.NumberInterface;
@@ -53,17 +52,11 @@ public class PluginManager {
      * The list of plugin listeners attached to this instance.
      */
     private Set<PluginListener> listeners;
-    /**
-     * The abacus instance used to access other
-     * components of the application.
-     */
-    private Abacus abacus;
 
     /**
      * Creates a new plugin manager.
      */
-    public PluginManager(Abacus abacus) {
-        this.abacus = abacus;
+    public PluginManager() {
         loadedPluginClasses = new HashSet<>();
         plugins = new HashSet<>();
         cachedFunctions = new HashMap<>();
@@ -167,13 +160,8 @@ public class PluginManager {
      * Loads all the plugins in the PluginManager.
      */
     public void load() {
-        Set<String> disabledPlugins = abacus.getConfiguration().getDisabledPlugins();
+        for (Plugin plugin : plugins) plugin.enable();
         for (Plugin plugin : plugins) {
-            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());
             allNumbers.addAll(plugin.providedNumbers());
@@ -185,18 +173,11 @@ public class PluginManager {
      * Unloads all the plugins in the PluginManager.
      */
     public void unload() {
-        listeners.forEach(e -> e.onUnload(this));
-        Set<String> disabledPlugins = abacus.getConfiguration().getDisabledPlugins();
-        for (Plugin plugin : plugins) {
-            if(disabledPlugins.contains(plugin.getClass().getName())) continue;
-            plugin.disable();
-        }
-        cachedFunctions.clear();
-        cachedOperators.clear();
-        cachedNumbers.clear();
+        for (Plugin plugin : plugins) plugin.disable();
         allFunctions.clear();
         allOperators.clear();
         allNumbers.clear();
+        listeners.forEach(e -> e.onUnload(this));
     }
 
     /**
@@ -204,7 +185,7 @@ public class PluginManager {
      */
     public void reload() {
         unload();
-        load();
+        reload();
     }
 
     /**
@@ -252,12 +233,4 @@ public class PluginManager {
         listeners.remove(listener);
     }
 
-    /**
-     * Gets a list of all the plugin class files that have been
-     * added to the plugin manager.
-     * @return the list of all the added plugin classes.
-     */
-    public Set<Class<?>> getLoadedPluginClasses() {
-        return loadedPluginClasses;
-    }
 }

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

@@ -8,8 +8,6 @@ import org.nwapw.abacus.number.NaiveNumber;
 import org.nwapw.abacus.number.NumberInterface;
 import org.nwapw.abacus.number.PreciseNumber;
 
-import java.util.ArrayList;
-import java.util.HashMap;
 import java.util.function.BiFunction;
 
 /**
@@ -18,8 +16,6 @@ import java.util.function.BiFunction;
  */
 public class StandardPlugin extends Plugin {
 
-    private static HashMap<Class<? extends NumberInterface>, ArrayList<NumberInterface>> factorialLists = new HashMap<Class<? extends NumberInterface>, ArrayList<NumberInterface>>();
-
     /**
      * The addition operator, +
      */
@@ -52,20 +48,6 @@ public class StandardPlugin extends Plugin {
             return params[0].subtract(params[1]);
         }
     });
-    /**
-     * The negation operator, -
-     */
-    public static final Operator OP_NEGATE = new Operator(OperatorAssociativity.LEFT, OperatorType.UNARY_PREFIX, 0, new Function() {
-        @Override
-        protected boolean matchesParams(NumberInterface[] params) {
-            return params.length == 1;
-        }
-
-        @Override
-        protected NumberInterface applyInternal(NumberInterface[] params) {
-            return params[0].negate();
-        }
-    });
     /**
      * The multiplication operator, *
      */
@@ -90,12 +72,16 @@ public class StandardPlugin extends Plugin {
     public static final Operator OP_DIVIDE = new Operator(OperatorAssociativity.LEFT, OperatorType.BINARY_INFIX, 1, new Function() {
         @Override
         protected boolean matchesParams(NumberInterface[] params) {
-            return params.length == 2;
+            return params.length >= 1;
         }
 
         @Override
         protected NumberInterface applyInternal(NumberInterface[] params) {
-            return params[0].divide(params[1]);
+            NumberInterface product = params[0];
+            for (int i = 1; i < params.length; i++) {
+                product = product.multiply(params[i]);
+            }
+            return product;
         }
     });
     /**
@@ -166,40 +152,17 @@ public class StandardPlugin extends Plugin {
 
         @Override
         protected NumberInterface applyInternal(NumberInterface[] params) {
-            NumberInterface maxError = getMaxError(params[0]);
-            int n = 0;
-            if(params[0].signum() <= 0){
-                NumberInterface currentTerm = NaiveNumber.ONE.promoteTo(params[0].getClass()), sum = currentTerm;
-                while(FUNCTION_ABS.apply(currentTerm).compareTo(maxError) > 0){
-                    n++;
-                    currentTerm = currentTerm.multiply(params[0]).divide((new NaiveNumber(n)).promoteTo(params[0].getClass()));
-                    sum = sum.add(currentTerm);
-                }
-                return sum;
-            }
-            else{
-                //We need n such that x^(n+1) * 3^ceil(x) <= maxError * (n+1)!.
-                //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())), right = maxError;
-                do{
-                    sum = sum.add(nextNumerator.divide(factorial(params[0].getClass(), n+1)));
-                    n++;
-                    nextNumerator = nextNumerator.multiply(params[0]);
-                    left = left.multiply(params[0]);
-                    NumberInterface nextN = (new NaiveNumber(n+1)).promoteTo(params[0].getClass());
-                    right = right.multiply(nextN);
-                    //System.out.println(left + ", " + right);
-                }
-                while(left.compareTo(right) > 0);
-                //System.out.println(n+1);
-                return sum;
+            boolean takeReciprocal = params[0].signum() == -1;
+            params[0] = FUNCTION_ABS.apply(params[0]);
+            NumberInterface sum = sumSeries(params[0], StandardPlugin::getExpSeriesTerm, getNTermsExp(getMaxError(params[0]), params[0]));
+            if (takeReciprocal) {
+                sum = NaiveNumber.ONE.promoteTo(sum.getClass()).divide(sum);
             }
+            return sum;
         }
     };
     /**
-     * The natural log function.
+     * The natural log function, ln(exp(1)) = 1
      */
     public static final Function FUNCTION_LN = new Function() {
         @Override
@@ -276,7 +239,7 @@ public class StandardPlugin extends Plugin {
         }
     };
     /**
-     * The square root function.
+     * The square root function, sqrt(4) = 2
      */
     public static final Function FUNCTION_SQRT = new Function() {
         @Override
@@ -294,6 +257,39 @@ public class StandardPlugin extends Plugin {
         super(manager);
     }
 
+    /**
+     * Returns the nth term of the Taylor series (centered at 0) of e^x
+     *
+     * @param n the term required (n >= 0).
+     * @param x the real number at which the series is evaluated.
+     * @return the nth term of the series.
+     */
+    private static NumberInterface getExpSeriesTerm(int n, NumberInterface x) {
+        return x.intPow(n).divide(OP_FACTORIAL.getFunction().apply((new NaiveNumber(n)).promoteTo(x.getClass())));
+    }
+
+    /**
+     * Returns the number of terms needed to evaluate the exponential function (at x)
+     * such that the error is at most maxError.
+     *
+     * @param maxError Maximum error permissible (This should probably be positive.)
+     * @param x        where the function is evaluated.
+     * @return the number of terms needed to evaluate the exponential function.
+     */
+    private static int getNTermsExp(NumberInterface maxError, NumberInterface x) {
+        //We need n such that |x^(n+1)| <= (n+1)! * maxError
+        //The variables LHS and RHS refer to the above inequality.
+        int n = 0;
+        x = FUNCTION_ABS.apply(x);
+        NumberInterface LHS = x, RHS = maxError;
+        while (LHS.compareTo(RHS) > 0) {
+            n++;
+            LHS = LHS.multiply(x);
+            RHS = RHS.multiply(new NaiveNumber(n + 1).promoteTo(RHS.getClass()));
+        }
+        return n;
+    }
+
     /**
      * Returns a partial sum of a series whose terms are given by the nthTermFunction, evaluated at x.
      *
@@ -327,7 +323,6 @@ public class StandardPlugin extends Plugin {
 
         registerOperator("+", OP_ADD);
         registerOperator("-", OP_SUBTRACT);
-        registerOperator("`", OP_NEGATE);
         registerOperator("*", OP_MULTIPLY);
         registerOperator("/", OP_DIVIDE);
         registerOperator("^", OP_CARET);
@@ -344,19 +339,4 @@ public class StandardPlugin extends Plugin {
 
     }
 
-    public static NumberInterface factorial(Class<? extends NumberInterface> numberClass, int n){
-        if(!factorialLists.containsKey(numberClass)){
-            factorialLists.put(numberClass, new ArrayList<>());
-            factorialLists.get(numberClass).add(NaiveNumber.ONE.promoteTo(numberClass));
-            factorialLists.get(numberClass).add(NaiveNumber.ONE.promoteTo(numberClass));
-        }
-        ArrayList<NumberInterface> list = factorialLists.get(numberClass);
-        if(n >= list.size()){
-            while(list.size() < n + 16){
-                list.add(list.get(list.size()-1).multiply(new NaiveNumber(list.size()).promoteTo(numberClass)));
-            }
-        }
-        return list.get(n);
-    }
-
 }

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

@@ -1,9 +1,11 @@
 package org.nwapw.abacus.tree;
 
+import org.nwapw.abacus.Abacus;
+
 /**
  * A tree node that represents an operation being applied to two operands.
  */
-public class BinaryNode extends TreeNode {
+public class BinaryInfixNode extends TreeNode {
 
     /**
      * The operation being applied.
@@ -17,8 +19,9 @@ public class BinaryNode extends TreeNode {
      * The right node of the operation.
      */
     private TreeNode right;
+    private Abacus trace;
 
-    private BinaryNode() {
+    private BinaryInfixNode() {
     }
 
     /**
@@ -27,8 +30,8 @@ public class BinaryNode extends TreeNode {
      *
      * @param operation the operation.
      */
-    public BinaryNode(String operation) {
-        this(operation, null, null);
+    public BinaryInfixNode(String operation,Abacus trace) {
+        this(operation, null, null,trace);
     }
 
     /**
@@ -39,10 +42,11 @@ public class BinaryNode extends TreeNode {
      * @param left      the left node of the expression.
      * @param right     the right node of the expression.
      */
-    public BinaryNode(String operation, TreeNode left, TreeNode right) {
+    public BinaryInfixNode(String operation, TreeNode left, TreeNode right,Abacus trace) {
         this.operation = operation;
         this.left = left;
         this.right = right;
+        this.trace = trace;
     }
 
     /**
@@ -92,10 +96,15 @@ public class BinaryNode extends TreeNode {
 
     @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);
+        if(!trace.getStop()) {
+            T leftReduce = left.reduce(reducer);
+
+            T rightReduce = right.reduce(reducer);
+            if (leftReduce == null || rightReduce == null) return null;
+            return reducer.reduceNode(this, leftReduce, rightReduce);
+        }
+        return null;
+
     }
 
     @Override

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

@@ -1,5 +1,7 @@
 package org.nwapw.abacus.tree;
 
+import org.nwapw.abacus.Abacus;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -16,6 +18,7 @@ public class FunctionNode extends TreeNode {
      * The list of arguments to the function.
      */
     private List<TreeNode> children;
+    private Abacus trace;
 
     /**
      * Creates a function node with no function.
@@ -28,9 +31,10 @@ public class FunctionNode extends TreeNode {
      *
      * @param function the function name.
      */
-    public FunctionNode(String function) {
+    public FunctionNode(String function,Abacus trace) {
         this.function = function;
         children = new ArrayList<>();
+        this.trace = trace;
     }
 
     /**

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

@@ -28,15 +28,15 @@ public class NumberReducer implements Reducer<NumberInterface> {
     public NumberInterface reduceNode(TreeNode node, Object... children) {
         if (node instanceof NumberNode) {
             return ((NumberNode) node).getNumber();
-        } else if (node instanceof BinaryNode) {
+        } else if (node instanceof BinaryInfixNode) {
             NumberInterface left = (NumberInterface) children[0];
             NumberInterface right = (NumberInterface) children[1];
-            Function function = abacus.getPluginManager().operatorFor(((BinaryNode) node).getOperation()).getFunction();
+            Function function = abacus.getPluginManager().operatorFor(((BinaryInfixNode) node).getOperation()).getFunction();
             if (function == null) return null;
             return function.apply(left, right);
-        } else if (node instanceof UnaryNode) {
+        } else if (node instanceof UnaryPrefixNode) {
             NumberInterface child = (NumberInterface) children[0];
-            Function functionn = abacus.getPluginManager().operatorFor(((UnaryNode) node).getOperation()).getFunction();
+            Function functionn = abacus.getPluginManager().operatorFor(((UnaryPrefixNode) node).getOperation()).getFunction();
             if (functionn == null) return null;
             return functionn.apply(child);
         } else if (node instanceof FunctionNode) {

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

@@ -1,6 +1,8 @@
 package org.nwapw.abacus.tree;
 
-public class UnaryNode extends TreeNode {
+import org.nwapw.abacus.Abacus;
+
+public class UnaryPrefixNode extends TreeNode {
 
     /**
      * The operation this node will apply.
@@ -10,14 +12,15 @@ public class UnaryNode extends TreeNode {
      * The tree node to apply the operation to.
      */
     private TreeNode applyTo;
+    private Abacus trace;
 
     /**
      * 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);
+    public UnaryPrefixNode(String operation,Abacus trace) {
+        this(operation, null,trace);
     }
 
     /**
@@ -26,16 +29,20 @@ public class UnaryNode extends TreeNode {
      * @param operation the operation for this node.
      * @param applyTo   the node to apply the function to.
      */
-    public UnaryNode(String operation, TreeNode applyTo) {
+    public UnaryPrefixNode(String operation, TreeNode applyTo,Abacus trace) {
         this.operation = operation;
         this.applyTo = applyTo;
+        this.trace = trace;
     }
 
     @Override
     public <T> T reduce(Reducer<T> reducer) {
-        Object reducedChild = applyTo.reduce(reducer);
-        if (reducedChild == null) return null;
-        return reducer.reduceNode(this, reducedChild);
+        if(!trace.getStop()) {
+            Object reducedChild = applyTo.reduce(reducer);
+            if (reducedChild == null) return null;
+            return reducer.reduceNode(this, reducedChild);
+        }
+        return null;
     }
 
     /**

src/main/java/org/nwapw/abacus/window/Window.java

@@ -15,13 +15,14 @@ import java.awt.event.MouseEvent;
  * The main UI window for the calculator.
  */
 public class Window extends JFrame {
+    
 
     private static final String CALC_STRING = "Calculate";
     private static final String SYNTAX_ERR_STRING = "Syntax Error";
     private static final String EVAL_ERR_STRING = "Evaluation Error";
     private static final String NUMBER_SYSTEM_LABEL = "Number Type:";
     private static final String FUNCTION_LABEL = "Functions:";
-
+    private static final String STOP_STRING = "Stop";
     /**
      * Array of Strings to which the "calculate" button's text
      * changes. For instance, in the graph tab, the name will
@@ -90,7 +91,10 @@ public class Window extends JFrame {
      * The "submit" button.
      */
     private JButton inputEnterButton;
-
+    /**
+     * The stop calculations button.
+     */
+    private JButton inputStopButton;
     /**
      * The side panel for separate configuration.
      */
@@ -113,26 +117,80 @@ public class Window extends JFrame {
      * The list of functions available to the user.
      */
     private JComboBox<String> functionList;
+    /**
+     * Thread used for calculations
+     */
+    private Thread calculateThread;
+    /**
+     * Check if currently calculating.
+     */
+    private boolean calculating;
+    /**
+     * Checks if thread should stop calculating.
+     */
+    private boolean stopCalculating;
+    /**
+     * Test variable to check number of threads running in the calculator.
+     */
+    private int count;
+    /**
+     * ActionListener that stops calculations.
+     */
+    private ActionListener stopListener = (event) -> {
+        //System.out.println(count++);  //Shows about how many calculation threads are running with the calculating=false command
+        //calculating = false;          //Ignores result of calculation and allows for the start of a new calculation
+        stopCalculating = true;         //Stops calculation at the next node check
+        //calculateThread.stop();         //Stops thread no matter what, Unsafe
+    };
 
     /**
-     * Action listener that causes the input to be evaluated.
+     * Node check to get whether nodes should continue calculating.
+     * @return boolean stop calculations if true.
+     */
+    public boolean getStop(){
+        return stopCalculating;
+    }
+
+    /**
+     * ActionListener that runs all calculations.
      */
     private ActionListener evaluateListener = (event) -> {
-        TreeNode parsedExpression = abacus.parseString(inputField.getText());
-        if (parsedExpression == null) {
-            lastOutputArea.setText(SYNTAX_ERR_STRING);
-            return;
+        Runnable calculate = new Runnable() {
+            public void run() {
+                boolean skip = false;
+                calculating = true;
+                TreeNode parsedExpression = null;
+                parsedExpression = abacus.parseString(inputField.getText());
+                if (parsedExpression == null) {
+                    lastOutputArea.setText(SYNTAX_ERR_STRING);
+                    skip = true;
+                }
+                if(!skip){
+                    NumberInterface numberInterface = abacus.evaluateTree(parsedExpression);
+                    if (numberInterface == null) {
+                        lastOutputArea.setText(EVAL_ERR_STRING);
+                        calculating = false;
+                        stopCalculating = false;
+
+                        return;
+                    }
+                    if(calculateThread.equals(Thread.currentThread())) {
+                        lastOutput = numberInterface.toString();
+                        historyModel.addEntry(new HistoryTableModel.HistoryEntry(inputField.getText(), parsedExpression, lastOutput));
+                        historyTable.invalidate();
+                        lastOutputArea.setText(lastOutput);
+                        inputField.setText("");
+                        calculating = false;
+                        stopCalculating = false;
+                    }
+                }
+            }
+        };
+        if(!calculating) {
+            calculateThread = new Thread(calculate);
+            calculateThread.setName("a-"+System.currentTimeMillis());
+            calculateThread.start();
         }
-        NumberInterface numberInterface = abacus.evaluateTree(parsedExpression);
-        if (numberInterface == null) {
-            lastOutputArea.setText(EVAL_ERR_STRING);
-            return;
-        }
-        lastOutput = numberInterface.toString();
-        historyModel.addEntry(new HistoryTableModel.HistoryEntry(inputField.getText(), parsedExpression, lastOutput));
-        historyTable.invalidate();
-        lastOutputArea.setText(lastOutput);
-        inputField.setText("");
     };
 
     /**
@@ -143,6 +201,14 @@ public class Window extends JFrame {
             evaluateListener,
             null
     };
+    /**
+     * Array of listeners that tell the stop button how to behave
+     * at a given input tab.
+     */
+    private ActionListener[] stopListeners = {
+            stopListener,
+            null
+    };
 
     /**
      * Creates a new window with the given manager.
@@ -152,6 +218,7 @@ public class Window extends JFrame {
     public Window(Abacus abacus) {
         this();
         this.abacus = abacus;
+        abacus.setWindow(this);
     }
 
     /**
@@ -160,25 +227,36 @@ public class Window extends JFrame {
     private Window() {
         super();
 
+        //variables related to when calculations occur
+        stopCalculating = false;
+        calculating = true;
+
         lastOutput = "";
 
+        //default window properties
         setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
         setSize(320, 480);
 
+        //initiates input objects
         inputField = new JTextField();
         inputEnterButton = new JButton(CALC_STRING);
+        inputStopButton = new JButton(STOP_STRING);
 
+        //adds input objects into Panel
         inputPanel = new JPanel();
         inputPanel.setLayout(new BorderLayout());
-        inputPanel.add(inputField, BorderLayout.CENTER);
-        inputPanel.add(inputEnterButton, BorderLayout.SOUTH);
+        inputPanel.add(inputStopButton, BorderLayout.SOUTH);
+        inputPanel.add(inputField, BorderLayout.NORTH);
+        inputPanel.add(inputEnterButton, BorderLayout.CENTER);
 
+        //initiates output objects in calculator tab
         historyModel = new HistoryTableModel();
         historyTable = new JTable(historyModel);
         historyScroll = new JScrollPane(historyTable);
         lastOutputArea = new JTextArea(lastOutput);
         lastOutputArea.setEditable(false);
 
+        //adds output objects into Panel
         calculationPanel = new JPanel();
         calculationPanel.setLayout(new BorderLayout());
         calculationPanel.add(historyScroll, BorderLayout.CENTER);
@@ -208,6 +286,8 @@ public class Window extends JFrame {
         settingsPanel.add(numberSystemPanel);
         settingsPanel.add(functionSelectPanel);
 
+        calculating = false;
+
         pane = new JTabbedPane();
         pane.add("Calculator", calculationPanel);
         pane.add("Settings", settingsPanel);
@@ -215,17 +295,23 @@ public class Window extends JFrame {
             int selectionIndex = pane.getSelectedIndex();
             boolean enabled = INPUT_ENABLED[selectionIndex];
             ActionListener listener = listeners[selectionIndex];
+            ActionListener stopUsed = stopListeners[selectionIndex];
             inputEnterButton.setText(BUTTON_NAMES[selectionIndex]);
             inputField.setEnabled(enabled);
             inputEnterButton.setEnabled(enabled);
+            inputStopButton.setEnabled(enabled);
 
             for (ActionListener removingListener : inputEnterButton.getActionListeners()) {
                 inputEnterButton.removeActionListener(removingListener);
                 inputField.removeActionListener(removingListener);
             }
+            for(ActionListener removingListener : inputStopButton.getActionListeners()){
+                inputStopButton.removeActionListener(removingListener);
+            }
             if (listener != null) {
                 inputEnterButton.addActionListener(listener);
                 inputField.addActionListener(listener);
+                inputStopButton.addActionListener(stopUsed);
             }
         });
         add(pane, BorderLayout.CENTER);
@@ -233,6 +319,7 @@ public class Window extends JFrame {
 
         inputEnterButton.addActionListener(evaluateListener);
         inputField.addActionListener(evaluateListener);
+        inputStopButton.addActionListener(stopListener);
         historyTable.addMouseListener(new MouseAdapter() {
             @Override
             public void mouseClicked(MouseEvent e) {

src/main/resources/abacus.fxml

@@ -1,61 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-
-<?import javafx.geometry.Insets?>
-<?import javafx.scene.control.*?>
-<?import javafx.scene.layout.BorderPane?>
-<?import javafx.scene.layout.VBox?>
-<?import javafx.scene.text.Text?>
-<?import javafx.scene.layout.HBox?>
-<?import javafx.scene.layout.GridPane?>
-<BorderPane xmlns="http://javafx.com/javafx"
-            xmlns:fx="http://javafx.com/fxml"
-            fx:controller="org.nwapw.abacus.fx.AbacusController">
-    <center>
-        <TabPane>
-            <Tab text="Calculator" closable="false">
-                <BorderPane>
-                    <center>
-                        <TableView fx:id="historyTable">
-                            <columnResizePolicy>
-                                <TableView fx:constant="CONSTRAINED_RESIZE_POLICY"/>
-                            </columnResizePolicy>
-                            <columns>
-                                <TableColumn fx:id="inputColumn" text="Input" sortable="false"/>
-                                <TableColumn fx:id="parsedColumn" text="Parsed" sortable="false"/>
-                                <TableColumn fx:id="outputColumn" text="Output" sortable="false"/>
-                            </columns>
-                        </TableView>
-                    </center>
-                    <bottom>
-                        <VBox>
-                            <ScrollPane prefHeight="50" vbarPolicy="NEVER">
-                                <padding>
-                                    <Insets top="10" bottom="10" left="10" right="10"/>
-                                </padding>
-                                <Text fx:id="outputText"/>
-                            </ScrollPane>
-                            <TextField fx:id="inputField" onAction="#performCalculation"/>
-                            <Button fx:id="inputButton" text="Calculate" maxWidth="Infinity"
-                                    onAction="#performCalculation"/>
-                        </VBox>
-                    </bottom>
-                </BorderPane>
-            </Tab>
-            <Tab text="Settings" closable="false">
-                <GridPane hgap="10" vgap="10">
-                    <padding><Insets left="10" right="10" top="10" bottom="10"/></padding>
-                    <Label text="Number Implementation" GridPane.columnIndex="0" GridPane.rowIndex="0"/>
-                    <ComboBox fx:id="numberImplementationBox" GridPane.columnIndex="1" GridPane.rowIndex="0"/>
-                    <ListView fx:id="enabledPluginView"
-                              GridPane.rowIndex="1" GridPane.columnIndex="0"
-                              GridPane.columnSpan="2" maxHeight="100"/>
-                    <HBox GridPane.columnIndex="0" GridPane.columnSpan="2" GridPane.rowIndex="2" spacing="10">
-                        <Button text="Apply" onAction="#performSave"/>
-                        <Button text="Reload" onAction="#performReload"/>
-                    </HBox>
-                </GridPane>
-            </Tab>
-        </TabPane>
-    </center>
-
-</BorderPane>