add stop on node

README.md

@@ -5,10 +5,10 @@ Summer project for NWAPW.
 Created by Arthur Drobot, Danila Fedorin and Riley Jones.
 
 ## Project Description
-Abacus is a calculator built with extensibility and usability in mind. It provides a plugin interface, via Java, as Lua proves too difficult to link up to the Java core. The description of the internals of the project can be found on the wiki page.
+Abacus is a calculator built with extensibility and usability in mind. It provides a plugin interface, via Java, as Lua provides too difficult to link up to the Java core. The description of the internals of the project can be found on the wiki page.
 
 ## Current State
-Abacus is being built for the Northwest Advanced Programming Workshop, a 3 week program in which students work in teams to complete a single project, following principles of agile development. Because of its short timeframe, Abacus is not even close to completed state. Below is a list of the current features and problems.
+Abacus is being built for the Northwest Advanced Programming Workshop, a 3 week program in which students work in treams to complete a single project, following principles of agile development. Because of its short timeframe, Abacus is not even close to completed state. Below is a list of the current features and problems.
 - [x] Basic number class
 - [x] Implementation of basic functions 
 - [x] Implementation of `exp`, `ln`, `sqrt` using the basic functions and Taylor Series

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.config.ConfigurationObject;
-import org.nwapw.abacus.fx.AbacusApplication;
 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();
         numberReducer = new NumberReducer(this);
-        configuration = new Configuration(CONFIG_FILE);
+        configuration = new ConfigurationObject(CONFIG_FILE);
-        configuration.saveTo(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

@@ -1,83 +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;
-
 /**
- * The configuration object that stores
+ * Serializable class that will be used to load TOML
- * options that the user can change.
+ * configurations.
  */
 public class Configuration {
 
     /**
-     * The TOML writer used to write this configuration to a file.
+     * The type of number this calculator should use.
      */
-    private static final TomlWriter TOML_WRITER = new TomlWriter();
+    public String numberType;
-    /**
-     * The TOML reader used to load this config from a file.
-     */
-    private static final Toml TOML_READER = new Toml();
 
-    /**
-     * The implementation of the number that should be used.
-     */
-    private String numberImplementation = "naive";
-
-    /**
-     * Creates a new configuration with the given values.
-     * @param numberImplementation the number implementation, like "naive" or "precise"
-     */
-    public Configuration(String numberImplementation){
-        this.numberImplementation = numberImplementation;
-    }
-
-    /**
-     * 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(TOML_READER.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;
-    }
-
-    /**
-     * 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;
-    }
 }

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

@@ -1,167 +0,0 @@
-package org.nwapw.abacus.fx;
-
-import javafx.application.Platform;
-import javafx.collections.FXCollections;
-import javafx.collections.ObservableList;
-import javafx.fxml.FXML;
-import javafx.scene.control.*;
-import javafx.scene.text.Text;
-import javafx.util.Callback;
-import org.nwapw.abacus.Abacus;
-import org.nwapw.abacus.number.NumberInterface;
-import org.nwapw.abacus.tree.TreeNode;
-
-
-/**
- * The controller for the abacus FX UI, responsible
- * for all the user interaction.
- */
-public class AbacusController {
-
-    /**
-     * 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";
-    /**
-     * Constant string that is displayed if the calculations are stopped before they are done.
-     */
-    private static final String ERR_STOP = "Stopped";
-    @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;
-
-    /**
-     * 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;
-
-    /**
-     * Thread used for calculating.
-     */
-    private Thread calcThread;
-
-    /**
-     * Checks whether the calculator is calculating.
-     */
-    private boolean calculating;
-
-    /**
-     * Seconds delayed for timer;
-     */
-    private double delay = 0;
-    private Abacus abacus;
-
-    @FXML
-    public void initialize(){
-        Callback<TableColumn<HistoryModel, String>, TableCell<HistoryModel, String>> cellFactory =
-                param -> new CopyableCell<>();
-
-        historyData = FXCollections.observableArrayList();
-        historyTable.setItems(historyData);
-        numberImplementationOptions = FXCollections.observableArrayList();
-        numberImplementationBox.setItems(numberImplementationOptions);
-        numberImplementationBox.valueProperty().addListener((observable, oldValue, newValue)
-                -> {
-            abacus.getConfiguration().setNumberImplementation(newValue);
-            abacus.getConfiguration().saveTo(Abacus.CONFIG_FILE);
-        });
-        historyTable.getSelectionModel().setCellSelectionEnabled(true);
-        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();
-        numberImplementationOptions.addAll(abacus.getPluginManager().getAllNumbers());
-        String actualImplementation = abacus.getConfiguration().getNumberImplementation();
-        String toSelect = (numberImplementationOptions.contains(actualImplementation)) ? actualImplementation : "naive";
-        numberImplementationBox.getSelectionModel().select(toSelect);
-    }
-
-    @FXML
-    private void performCalculation(){
-        Runnable calculator = new Runnable(){
-            public void run() {
-                if(delay>0) {
-                    Runnable timer = new Runnable() {
-                        public void run() {
-                            long gap = (long) (delay * 1000);
-                            long startTime = System.currentTimeMillis();
-                            while (System.currentTimeMillis() - startTime <= gap) {
-                            }
-                            stopCalculation();
-                        }
-                    };
-                    Thread maxTime = new Thread(timer);
-                    maxTime.setName("maxTime");
-                    maxTime.start();
-                }
-                calculating = true;
-                Platform.runLater(() -> inputButton.setDisable(true));
-                TreeNode constructedTree = abacus.parseString(inputField.getText());
-                if (constructedTree == null) {
-                    Platform.runLater(() ->outputText.setText(ERR_SYNTAX));
-                    Platform.runLater(() -> inputButton.setDisable(false));
-                    //return;
-                }else {
-                    NumberInterface evaluatedNumber = abacus.evaluateTree(constructedTree);
-                    if (evaluatedNumber == null) {
-                        if(Thread.currentThread().isInterrupted()){
-                            Platform.runLater(() -> outputText.setText(ERR_STOP));
-                            Platform.runLater(() -> inputButton.setDisable(false));
-                        }else {
-                            Platform.runLater(() -> outputText.setText(ERR_EVAL));
-                            Platform.runLater(() -> inputButton.setDisable(false));
-                            //return;
-                        }
-                    } else {
-                        Platform.runLater(() -> outputText.setText(evaluatedNumber.toString()));
-
-                        historyData.add(new HistoryModel(inputField.getText(), constructedTree.toString(), evaluatedNumber.toString()));
-
-                        Platform.runLater(() -> inputButton.setDisable(false));
-                        Platform.runLater(() -> inputField.setText(""));
-                    }
-                }
-                calculating = false;
-            }
-        };
-        if(!calculating) {
-                calcThread = new Thread(calculator);
-                calcThread.setName("calcThread");
-                calcThread.start();
-        }
-    }
-    @FXML
-    private void stopCalculation(){
-        calcThread.interrupt();
-        calculating = false;
-        //Platform.runLater(() ->inputButton.setDisable(false));
-    }
-
-}

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/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;
+            TokenType matchType = match.getType();
-            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 ||
+                while (!tokenStack.empty()) {
-                        previousType == TokenType.OPEN_PARENTH)){
-                    from.add(0, new Match<>("`", TokenType.OP));
-                    continue;
-                }
-
-                while (!tokenStack.empty() && type == OperatorType.BINARY_INFIX) {
                     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();
+            TokenType matchType = match.getType();
-            if (!(newMatchType == TokenType.OP || newMatchType == TokenType.FUNCTION)) return null;
+            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 right = constructRecursive(matches,trace);
-                TreeNode left = constructRecursive(matches);
+                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/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, +
      */
@@ -31,13 +27,9 @@ public class StandardPlugin extends Plugin {
 
         @Override
         protected NumberInterface applyInternal(NumberInterface[] params) {
-            if(Thread.currentThread().isInterrupted())
-                return null;
             NumberInterface sum = params[0];
             for (int i = 1; i < params.length; i++) {
                 sum = sum.add(params[i]);
-                if(Thread.currentThread().isInterrupted())
-                    return null;
             }
             return sum;
         }
@@ -53,26 +45,7 @@ public class StandardPlugin extends Plugin {
 
         @Override
         protected NumberInterface applyInternal(NumberInterface[] params) {
-            if(Thread.currentThread().isInterrupted())
-                return null;
             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) {
-            if(Thread.currentThread().isInterrupted())
-                return null;
-            return params[0].negate();
         }
     });
     /**
@@ -86,13 +59,9 @@ public class StandardPlugin extends Plugin {
 
         @Override
         protected NumberInterface applyInternal(NumberInterface[] params) {
-            if(Thread.currentThread().isInterrupted())
-                return null;
             NumberInterface product = params[0];
             for (int i = 1; i < params.length; i++) {
                 product = product.multiply(params[i]);
-                if(Thread.currentThread().isInterrupted())
-                    return null;
             }
             return product;
         }
@@ -103,14 +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) {
-            if(Thread.currentThread().isInterrupted())
+            NumberInterface product = params[0];
-                return null;
+            for (int i = 1; i < params.length; i++) {
-            return params[0].divide(params[1]);
+                product = product.multiply(params[i]);
+            }
+            return product;
         }
     });
     /**
@@ -125,19 +96,15 @@ public class StandardPlugin extends Plugin {
 
         @Override
         protected NumberInterface applyInternal(NumberInterface[] params) {
-            if(Thread.currentThread().isInterrupted())
-                return null;
             if (params[0].signum() == 0) {
                 return (new NaiveNumber(1)).promoteTo(params[0].getClass());
             }
             NumberInterface factorial = params[0];
             NumberInterface multiplier = params[0];
             //It is necessary to later prevent calls of factorial on anything but non-negative integers.
-            while (!Thread.currentThread().isInterrupted()&&(multiplier = multiplier.subtract(NaiveNumber.ONE.promoteTo(multiplier.getClass())))!=null&&multiplier.signum() == 1) {
+            while ((multiplier = multiplier.subtract(NaiveNumber.ONE.promoteTo(multiplier.getClass()))).signum() == 1) {
                 factorial = factorial.multiply(multiplier);
             }
-            if(Thread.currentThread().isInterrupted())
-                return null;
             return factorial;
                 /*if(!storedList.containsKey(params[0].getClass())){
                     storedList.put(params[0].getClass(), new ArrayList<NumberInterface>());
@@ -157,12 +124,7 @@ public class StandardPlugin extends Plugin {
 
         @Override
         protected NumberInterface applyInternal(NumberInterface[] params) {
-            if(Thread.currentThread().isInterrupted())
+            return FUNCTION_EXP.apply(FUNCTION_LN.apply(params[0]).multiply(params[1]));
-                return null;
-            NumberInterface check;
-            if((check = FUNCTION_EXP.apply(FUNCTION_LN.apply(params[0])))!=null&&(check = check.multiply(params[1]))!=null)
-                return check;
-            return null;
         }
     });
     /**
@@ -176,8 +138,6 @@ public class StandardPlugin extends Plugin {
 
         @Override
         protected NumberInterface applyInternal(NumberInterface[] params) {
-            if(Thread.currentThread().isInterrupted())
-                return null;
             return params[0].multiply((new NaiveNumber(params[0].signum())).promoteTo(params[0].getClass()));
         }
     };
@@ -192,53 +152,17 @@ public class StandardPlugin extends Plugin {
 
         @Override
         protected NumberInterface applyInternal(NumberInterface[] params) {
-            if(Thread.currentThread().isInterrupted())
+            boolean takeReciprocal = params[0].signum() == -1;
-                return null;
+            params[0] = FUNCTION_ABS.apply(params[0]);
-            NumberInterface maxError = getMaxError(params[0]);
+            NumberInterface sum = sumSeries(params[0], StandardPlugin::getExpSeriesTerm, getNTermsExp(getMaxError(params[0]), params[0]));
-            int n = 0;
+            if (takeReciprocal) {
-            if(params[0].signum() <= 0){
+                sum = NaiveNumber.ONE.promoteTo(sum.getClass()).divide(sum);
-                NumberInterface currentTerm = NaiveNumber.ONE.promoteTo(params[0].getClass()), sum = currentTerm;
-                NumberInterface check;
-                while((check = FUNCTION_ABS.apply(currentTerm))!=null && (check.compareTo(maxError) > 0)){
-                    n++;
-                    if(Thread.currentThread().isInterrupted()||(currentTerm = currentTerm.multiply(params[0]))==null||(currentTerm = currentTerm.divide((new NaiveNumber(n)).promoteTo(params[0].getClass())))==null||(sum = (sum.add(currentTerm)))==null)
-                        return null;
-                }
-                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;
-                NumberInterface check;
-                        if((check =intPow(new NaiveNumber(3).promoteTo(params[0].getClass()),params[0].getClass(),(new NaiveNumber(params[0].ceiling())).promoteTo(params[0].getClass())))==null)
-                            return null;
-                        NumberInterface left = params[0].multiply(check), right = maxError;
-                do{
-                    if((check = factorial(params[0].getClass(),n+1))==null||(check = nextNumerator.divide(check))==null||(sum = sum.add(check))==null)
-                        return null;
-                    n++;
-                    if((nextNumerator = nextNumerator.multiply(params[0]))==null)
-                        return null;
-                    if((left = left.multiply(params[0]))==null)
-                        return null;
-                    NumberInterface nextN = (new NaiveNumber(n+1)).promoteTo(params[0].getClass());
-                    if((right = right.multiply(nextN))==null)
-                        return null;
-                    //System.out.println(left + ", " + right);
-                }
-                while(!Thread.currentThread().isInterrupted()&&left.compareTo(right) > 0);
-                //System.out.println(n+1);
-               if(Thread.currentThread().isInterrupted())
-                    return null;
-                return sum;
             }
+            return sum;
         }
     };
     /**
-     * The natural log function.
+     * The natural log function, ln(exp(1)) = 1
      */
     public static final Function FUNCTION_LN = new Function() {
         @Override
@@ -248,32 +172,26 @@ public class StandardPlugin extends Plugin {
 
         @Override
         protected NumberInterface applyInternal(NumberInterface[] params) {
-            if(Thread.currentThread().isInterrupted())
-                return null;
             NumberInterface param = params[0];
             int powersOf2 = 0;
-            NumberInterface check;
+            while (FUNCTION_ABS.apply(param.subtract(NaiveNumber.ONE.promoteTo(param.getClass()))).compareTo((new NaiveNumber(0.1)).promoteTo(param.getClass())) >= 0) {
-            while (!Thread.currentThread().isInterrupted()&&(check = FUNCTION_ABS.apply(param.subtract(NaiveNumber.ONE.promoteTo(param.getClass()))))!=null&&(check.compareTo((new NaiveNumber(0.1)).promoteTo(param.getClass()))) >= 0) {
+                if (param.subtract(NaiveNumber.ONE.promoteTo(param.getClass())).signum() == 1) {
-                if ((check = param.subtract(NaiveNumber.ONE.promoteTo(param.getClass())))!=null&&check.signum() == 1) {
                     param = param.divide(new NaiveNumber(2).promoteTo(param.getClass()));
                     powersOf2++;
-                    if ((check = param.subtract(NaiveNumber.ONE.promoteTo(param.getClass())))==null||check.signum() != 1) {
+                    if (param.subtract(NaiveNumber.ONE.promoteTo(param.getClass())).signum() != 1) {
                         break;
                         //No infinite loop for you.
                     }
                 } else {
                     param = param.multiply(new NaiveNumber(2).promoteTo(param.getClass()));
                     powersOf2--;
-                    if ((check = param.subtract(NaiveNumber.ONE.promoteTo(param.getClass())))==null||check.signum() != 1) {
+                    if (param.subtract(NaiveNumber.ONE.promoteTo(param.getClass())).signum() != 1) {
                         break;
                         //No infinite loop for you.
                     }
                 }
             }
-            NumberInterface check2;
+            return getLog2(param).multiply((new NaiveNumber(powersOf2)).promoteTo(param.getClass())).add(getLogPartialSum(param));
-            if(!Thread.currentThread().isInterrupted()&&(check = getLog2(param))!=null&&(check = check.multiply((new NaiveNumber(powersOf2).promoteTo(param.getClass()))))!=null&&(check2 = getLogPartialSum(param))!=null&&(check = check.add(check2))!=null)
-                   return check;
-            return null;
         }
 
         /**
@@ -283,23 +201,16 @@ public class StandardPlugin extends Plugin {
          * @return the partial sum.
          */
         private NumberInterface getLogPartialSum(NumberInterface x) {
-
-            if(Thread.currentThread().isInterrupted())
-                return null;
             NumberInterface maxError = getMaxError(x);
             x = x.subtract(NaiveNumber.ONE.promoteTo(x.getClass())); //Terms used are for log(x+1).
             NumberInterface currentNumerator = x, currentTerm = x, sum = x;
             int n = 1;
-            NumberInterface check;
+            while (FUNCTION_ABS.apply(currentTerm).compareTo(maxError) > 0) {
-            while (!Thread.currentThread().isInterrupted()&&(check = FUNCTION_ABS.apply(currentTerm))!=null&&check.compareTo(maxError) > 0) {
                 n++;
-                if((currentNumerator = currentNumerator.multiply(x))==null||(currentNumerator = currentNumerator.negate())==null)
+                currentNumerator = currentNumerator.multiply(x).negate();
-                    return null;
                 currentTerm = currentNumerator.divide(new NaiveNumber(n).promoteTo(x.getClass()));
                 sum = sum.add(currentTerm);
             }
-            if(Thread.currentThread().isInterrupted())
-                return null;
             return sum;
         }
 
@@ -309,8 +220,6 @@ public class StandardPlugin extends Plugin {
          * @return the value of log(2) with the appropriate precision.
          */
         private NumberInterface getLog2(NumberInterface number) {
-            if(Thread.currentThread().isInterrupted())
-                return null;
             NumberInterface maxError = getMaxError(number);
             //NumberInterface errorBound = (new NaiveNumber(1)).promoteTo(number.getClass());
             //We'll use the series \sigma_{n >= 1) ((1/3^n + 1/4^n) * 1/n)
@@ -319,22 +228,18 @@ public class StandardPlugin extends Plugin {
             NumberInterface a = (new NaiveNumber(1)).promoteTo(number.getClass()), b = a, c = a;
             NumberInterface sum = NaiveNumber.ZERO.promoteTo(number.getClass());
             int n = 0;
-            while (!Thread.currentThread().isInterrupted()&&a.compareTo(maxError) >= 1) {
+            while (a.compareTo(maxError) >= 1) {
                 n++;
                 a = a.divide((new NaiveNumber(3)).promoteTo(number.getClass()));
                 b = b.divide((new NaiveNumber(4)).promoteTo(number.getClass()));
                 c = NaiveNumber.ONE.promoteTo(number.getClass()).divide((new NaiveNumber(n)).promoteTo(number.getClass()));
-                NumberInterface check;
+                sum = sum.add(a.add(b).multiply(c));
-                if(a==null||(check = a.add(b))==null||(check = check.multiply(c))==null||(sum = sum.add(check))==null)
-                    return null;
             }
-            if(Thread.currentThread().isInterrupted())
-                return null;
             return sum;
         }
     };
     /**
-     * The square root function.
+     * The square root function, sqrt(4) = 2
      */
     public static final Function FUNCTION_SQRT = new Function() {
         @Override
@@ -352,6 +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.
      *
@@ -385,7 +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);
@@ -402,44 +339,4 @@ public class StandardPlugin extends Plugin {
 
     }
 
-    public static NumberInterface factorial(Class<? extends NumberInterface> numberClass, int n){
-        if(Thread.currentThread().isInterrupted())
-            return null;
-        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(!Thread.currentThread().isInterrupted()&&list.size() < n + 16){
-                list.add(list.get(list.size()-1).multiply(new NaiveNumber(list.size()).promoteTo(numberClass)));
-            }
-        }
-        if(Thread.currentThread().isInterrupted())
-            return null;
-        return list.get(n);
-    }
-    public static NumberInterface intPow(NumberInterface number, Class<? extends NumberInterface> numberClass,NumberInterface exponent) {
-        if(Thread.currentThread().isInterrupted())
-            return null;
-        if (exponent.compareTo((new NaiveNumber(0)).promoteTo(numberClass))==0) {
-            return (new NaiveNumber(1)).promoteTo(numberClass);
-        }
-        boolean takeReciprocal = exponent.compareTo((new NaiveNumber(0)).promoteTo(numberClass))<0;
-        exponent = FUNCTION_ABS.apply(exponent);
-        NumberInterface power = number;
-        for(NumberInterface currentExponent =(new NaiveNumber(1)).promoteTo(numberClass);currentExponent.compareTo(exponent)<0;currentExponent = currentExponent.add((new NaiveNumber(1)).promoteTo(numberClass))){
-            power = power.multiply(number);
-            if(Thread.currentThread().isInterrupted())
-                return null;
-        }
-        if (takeReciprocal) {
-            power = (new NaiveNumber(1)).promoteTo(numberClass).divide(power);
-        }
-        if(Thread.currentThread().isInterrupted())
-            return null;
-        return power;
-    }
-
 }

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) {
+    public BinaryInfixNode(String operation,Abacus trace) {
-        this(operation, null, null);
+        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;
     }
 
     /**
@@ -92,15 +96,15 @@ public class BinaryNode extends TreeNode {
 
     @Override
     public <T> T reduce(Reducer<T> reducer) {
-        if(Thread.currentThread().isInterrupted())
+        if(!trace.getStop()) {
-            return null;
+            T leftReduce = left.reduce(reducer);
-        T leftReduce = left.reduce(reducer);
+
-        T rightReduce = right.reduce(reducer);
+            T rightReduce = right.reduce(reducer);
-        if (leftReduce == null || rightReduce == null) return null;
+            if (leftReduce == null || rightReduce == null) return null;
-        T a = reducer.reduceNode(this, leftReduce, rightReduce);
+            return reducer.reduceNode(this, leftReduce, rightReduce);
-        if(Thread.currentThread().isInterrupted())
+        }
-            return null;
+        return null;
-        return a;
+
     }
 
     @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;
     }
 
     /**
@@ -62,17 +66,12 @@ public class FunctionNode extends TreeNode {
 
     @Override
     public <T> T reduce(Reducer<T> reducer) {
-        if(Thread.currentThread().isInterrupted())
-            return null;
         Object[] reducedChildren = new Object[children.size()];
         for (int i = 0; i < reducedChildren.length; i++) {
             reducedChildren[i] = children.get(i).reduce(reducer);
-            if (Thread.currentThread().isInterrupted()||reducedChildren[i] == null) return null;
+            if (reducedChildren[i] == null) return null;
         }
-        T a = reducer.reduceNode(this, reducedChildren);
+        return reducer.reduceNode(this, reducedChildren);
-        if(Thread.currentThread().isInterrupted())
-            return null;
-        return a;
     }
 
     @Override

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) {
+    public UnaryPrefixNode(String operation,Abacus trace) {
-        this(operation, null);
+        this(operation, null,trace);
     }
 
     /**
@@ -26,21 +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) {
-        if(Thread.currentThread().isInterrupted())
+        if(!trace.getStop()) {
-            return null;
+            Object reducedChild = applyTo.reduce(reducer);
-        Object reducedChild = applyTo.reduce(reducer);
+            if (reducedChild == null) return null;
-        if (reducedChild == null) return null;
+            return reducer.reduceNode(this, reducedChild);
-        T a = reducer.reduceNode(this, reducedChild);
+        }
-        if(Thread.currentThread().isInterrupted())
+        return null;
-            return null;
-        return a;
     }
 
     /**

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());
+        Runnable calculate = new Runnable() {
-        if (parsedExpression == null) {
+            public void run() {
-            lastOutputArea.setText(SYNTAX_ERR_STRING);
+                boolean skip = false;
-            return;
+                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(inputStopButton, BorderLayout.SOUTH);
-        inputPanel.add(inputEnterButton, 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

@@ -1,56 +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"/>
-                            <Button fx:id="stopButton" text="Stop" maxWidth="Infinity"
-                                    onAction="#stopCalculation"/>
-                        </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"/>
-                </GridPane>
-            </Tab>
-        </TabPane>
-    </center>
-
-</BorderPane>