Implement the negation operator.

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
+    BINARY_INFIX, UNARY_POSTFIX, UNARY_PREFIX
 }

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

@@ -6,6 +6,10 @@ 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

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

@@ -11,9 +11,19 @@ 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";
 
     @FXML
@@ -33,8 +43,15 @@ public class AbacusController {
     @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;
 
     private Abacus abacus;

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

@@ -6,8 +6,17 @@ 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){

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

@@ -3,12 +3,33 @@ 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();
@@ -18,23 +39,47 @@ public class HistoryModel {
         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/PreciseNumber.java

@@ -1,9 +1,12 @@
 package org.nwapw.abacus.number;
 
 import java.math.BigDecimal;
-import java.math.MathContext;
 import java.math.RoundingMode;
 
+/**
+ * A number that uses a BigDecimal to store its value,
+ * leading to infinite possible precision.
+ */
 public class PreciseNumber implements NumberInterface {
 
     /**

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

@@ -55,9 +55,12 @@ 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);
-            TokenType matchType = match.getType();
+            previousType = matchType;
+            matchType = match.getType();
             if (matchType == TokenType.NUM) {
                 output.add(match);
             } else if (matchType == TokenType.FUNCTION) {
@@ -74,7 +77,13 @@ public class ShuntingYardParser implements Parser<Match<TokenType>>, PluginListe
                     continue;
                 }
 
-                while (!tokenStack.empty()) {
+                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) {
                     Match<TokenType> otherMatch = tokenStack.peek();
                     TokenType otherMatchType = otherMatch.getType();
                     if (!(otherMatchType == TokenType.OP || otherMatchType == TokenType.FUNCTION)) break;
@@ -103,8 +112,8 @@ public class ShuntingYardParser implements Parser<Match<TokenType>>, PluginListe
         }
         while (!tokenStack.empty()) {
             Match<TokenType> match = tokenStack.peek();
-            TokenType matchType = match.getType();
-            if (!(matchType == TokenType.OP || matchType == TokenType.FUNCTION)) return null;
+            TokenType newMatchType = match.getType();
+            if (!(newMatchType == TokenType.OP || newMatchType == TokenType.FUNCTION)) return null;
             output.add(tokenStack.pop());
         }
         return output;
@@ -127,11 +136,11 @@ public class ShuntingYardParser implements Parser<Match<TokenType>>, PluginListe
                 TreeNode right = constructRecursive(matches);
                 TreeNode left = constructRecursive(matches);
                 if (left == null || right == null) return null;
-                else return new BinaryInfixNode(operator, left, right);
+                else return new BinaryNode(operator, left, right);
             } else {
                 TreeNode applyTo = constructRecursive(matches);
                 if (applyTo == null) return null;
-                else return new UnaryPrefixNode(operator, applyTo);
+                else return new UnaryNode(operator, applyTo);
             }
         } else if (matchType == TokenType.NUM) {
             return new NumberNode(abacus.numberFromString(match.getContent()));

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

@@ -52,6 +52,20 @@ 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, *
      */
@@ -317,6 +331,7 @@ public class StandardPlugin extends Plugin {
 
         registerOperator("+", OP_ADD);
         registerOperator("-", OP_SUBTRACT);
+        registerOperator("`", OP_NEGATE);
         registerOperator("*", OP_MULTIPLY);
         registerOperator("/", OP_DIVIDE);
         registerOperator("^", OP_CARET);
@@ -335,7 +350,7 @@ public class StandardPlugin extends Plugin {
 
     public static NumberInterface factorial(Class<? extends NumberInterface> numberClass, int n){
         if(!factorialLists.containsKey(numberClass)){
-            factorialLists.put(numberClass, new ArrayList<NumberInterface>());
+            factorialLists.put(numberClass, new ArrayList<>());
             factorialLists.get(numberClass).add(NaiveNumber.ONE.promoteTo(numberClass));
             factorialLists.get(numberClass).add(NaiveNumber.ONE.promoteTo(numberClass));
         }

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

@@ -3,7 +3,7 @@ package org.nwapw.abacus.tree;
 /**
  * A tree node that represents an operation being applied to two operands.
  */
-public class BinaryInfixNode extends TreeNode {
+public class BinaryNode extends TreeNode {
 
     /**
      * The operation being applied.
@@ -18,7 +18,7 @@ public class BinaryInfixNode extends TreeNode {
      */
     private TreeNode right;
 
-    private BinaryInfixNode() {
+    private BinaryNode() {
     }
 
     /**
@@ -27,7 +27,7 @@ public class BinaryInfixNode extends TreeNode {
      *
      * @param operation the operation.
      */
-    public BinaryInfixNode(String operation) {
+    public BinaryNode(String operation) {
         this(operation, null, null);
     }
 
@@ -39,7 +39,7 @@ public class BinaryInfixNode extends TreeNode {
      * @param left      the left node of the expression.
      * @param right     the right node of the expression.
      */
-    public BinaryInfixNode(String operation, TreeNode left, TreeNode right) {
+    public BinaryNode(String operation, TreeNode left, TreeNode right) {
         this.operation = operation;
         this.left = left;
         this.right = right;

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 BinaryInfixNode) {
+        } else if (node instanceof BinaryNode) {
             NumberInterface left = (NumberInterface) children[0];
             NumberInterface right = (NumberInterface) children[1];
-            Function function = abacus.getPluginManager().operatorFor(((BinaryInfixNode) node).getOperation()).getFunction();
+            Function function = abacus.getPluginManager().operatorFor(((BinaryNode) node).getOperation()).getFunction();
             if (function == null) return null;
             return function.apply(left, right);
-        } else if (node instanceof UnaryPrefixNode) {
+        } else if (node instanceof UnaryNode) {
             NumberInterface child = (NumberInterface) children[0];
-            Function functionn = abacus.getPluginManager().operatorFor(((UnaryPrefixNode) node).getOperation()).getFunction();
+            Function functionn = abacus.getPluginManager().operatorFor(((UnaryNode) node).getOperation()).getFunction();
             if (functionn == null) return null;
             return functionn.apply(child);
         } else if (node instanceof FunctionNode) {

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

@@ -1,6 +1,6 @@
 package org.nwapw.abacus.tree;
 
-public class UnaryPrefixNode extends TreeNode {
+public class UnaryNode extends TreeNode {
 
     /**
      * The operation this node will apply.
@@ -16,7 +16,7 @@ public class UnaryPrefixNode extends TreeNode {
      *
      * @param operation the operation for this node.
      */
-    public UnaryPrefixNode(String operation) {
+    public UnaryNode(String operation) {
         this(operation, null);
     }
 
@@ -26,7 +26,7 @@ public class UnaryPrefixNode extends TreeNode {
      * @param operation the operation for this node.
      * @param applyTo   the node to apply the function to.
      */
-    public UnaryPrefixNode(String operation, TreeNode applyTo) {
+    public UnaryNode(String operation, TreeNode applyTo) {
         this.operation = operation;
         this.applyTo = applyTo;
     }