Fix null pointer exceptions associated with turning ! into an operator.

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

@@ -9,6 +9,10 @@ public class Operator {
      * The associativity of the operator.
      */
     private OperatorAssociativity associativity;
+    /**
+     * The type of this operator.
+     */
+    private OperatorType type;
     /**
      * The precedence of the operator.
      */
@@ -24,8 +28,9 @@ public class Operator {
      * @param precedence the precedence of the operator.
      * @param function the function that the operator calls.
      */
-    public Operator(OperatorAssociativity associativity, int precedence, Function function){
+    public Operator(OperatorAssociativity associativity, OperatorType operatorType, int precedence, Function function){
         this.associativity = associativity;
+        this.type = operatorType;
         this.precedence = precedence;
         this.function = function;
     }
@@ -38,6 +43,14 @@ public class Operator {
         return associativity;
     }
 
+    /**
+     * Gets the operator's type.
+     * @return the type.
+     */
+    public OperatorType getType() {
+        return type;
+    }
+
     /**
      * Gets the operator's precedence.
      * @return the precedence.

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

@@ -0,0 +1,8 @@
+package org.nwapw.abacus.function;
+
+/**
+ * The type of an operator, describing how it should behave.
+ */
+public enum OperatorType {
+    BINARY_INFIX, UNARY_POSTFIX
+}

src/org/nwapw/abacus/lexing/Lexer.java

@@ -54,7 +54,7 @@ public class Lexer<T> {
     /**
      * The registered patterns.
      */
-    private HashMap<PatternEntry<T>, Pattern<T>> patterns;
+    private Map<PatternEntry<T>, Pattern<T>> patterns;
 
     /**
      * Creates a new lexer with no registered patterns.
@@ -127,7 +127,7 @@ public class Lexer<T> {
      * @param compare the comparator used to sort matches by their IDs.
      * @return the resulting list of matches, in order, or null on error.
      */
-    public ArrayList<Match<T>> lexAll(String from, int startAt, Comparator<T> compare){
+    public List<Match<T>> lexAll(String from, int startAt, Comparator<T> compare){
         int index = startAt;
         ArrayList<Match<T>> matches = new ArrayList<>();
         Match<T> lastMatch = null;

src/org/nwapw/abacus/lexing/pattern/Pattern.java

@@ -2,6 +2,7 @@ package org.nwapw.abacus.lexing.pattern;
 
 import java.util.Collection;
 import java.util.HashMap;
+import java.util.Map;
 import java.util.Stack;
 import java.util.function.Function;
 
@@ -32,7 +33,7 @@ public class Pattern<T> {
      * A map of regex operator to functions that modify a PatternChain
      * with the appropriate operation.
      */
-    private HashMap<Character, Function<PatternChain<T>, PatternChain<T>>> operations =
+    private Map<Character, Function<PatternChain<T>, PatternChain<T>>> operations =
             new HashMap<Character, Function<PatternChain<T>, PatternChain<T>>>() {{
                 put('+', Pattern.this::transformPlus);
                 put('*', Pattern.this::transformStar);

src/org/nwapw/abacus/lexing/pattern/PatternNode.java

@@ -3,6 +3,7 @@ package org.nwapw.abacus.lexing.pattern;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashSet;
+import java.util.Set;
 
 /**
  * A base class for a pattern node. Provides all functions
@@ -16,7 +17,7 @@ public class PatternNode<T> {
      * The set of states to which the lexer should continue
      * should this node be correctly matched.
      */
-    protected HashSet<PatternNode<T>> outputStates;
+    protected Set<PatternNode<T>> outputStates;
 
     /**
      * Creates a new pattern node.

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

@@ -4,6 +4,7 @@ import org.nwapw.abacus.function.Function;
 import org.nwapw.abacus.function.Operator;
 
 import java.util.HashMap;
+import java.util.Map;
 import java.util.Set;
 
 /**
@@ -18,11 +19,11 @@ public abstract class Plugin {
     /**
      * A hash map of functions mapped to their string names.
      */
-    private HashMap<String, Function> functions;
+    private Map<String, Function> functions;
     /**
      * A hash map of operators mapped to their string names.
      */
-    private HashMap<String, Operator> operators;
+    private Map<String, Operator> operators;
     /**
      * The plugin manager in which to search for functions
      * not inside this package,

src/org/nwapw/abacus/plugin/PluginLoader.java

@@ -1,106 +0,0 @@
-package org.nwapw.abacus.plugin;
-
-import java.io.File;
-import java.io.IOException;
-import java.net.URL;
-import java.net.URLClassLoader;
-import java.util.ArrayList;
-import java.util.Properties;
-import java.util.jar.JarFile;
-
-/**
- * A plugin loader, used to scan a directory for
- * plugins and load them into classes that can then be
- * used by the plugin manager.
- */
-public class PluginLoader {
-
-    /**
-     * An internal class that represents a Jar file that
-     * has been founded, but not loaded.
-     */
-    private static final class PluginEntry {
-        String mainClass;
-        File jarPath;
-    }
-
-    /**
-     * The path which to search for plugins.
-     */
-    private File path;
-    /**
-     * The array of loaded plugin main classes.
-     */
-    private ArrayList<Class<?>> foundMainClasses;
-
-    /**
-     * Creates a new plugin loader at the given path.
-     * @param path the path which to search for plugins.
-     */
-    public PluginLoader(File path) {
-        this.path = path;
-    }
-
-    /**
-     * Loads all the plugin classes that have been found.
-     * @return the list of loaded classes.
-     * @throws IOException thrown when loading classes from URL fails.
-     * @throws ClassNotFoundException thrown when the class specified in plugin.properties is missing.
-     */
-    private ArrayList<Class<?>> loadPluginClasses() throws IOException, ClassNotFoundException {
-        ArrayList<Class<?>> foundMainClasses = new ArrayList<>();
-        for(PluginEntry entry : findPlugins()){
-            if(entry.mainClass == null) continue;
-            ClassLoader loader = URLClassLoader.newInstance(
-                    new URL[]{ entry.jarPath.toURI().toURL() },
-                    getClass().getClassLoader());
-            Class<?> loadedClass = loader.loadClass(entry.mainClass);
-            if(!Plugin.class.isAssignableFrom(loadedClass)) continue;
-            foundMainClasses.add(loadedClass);
-        }
-        return foundMainClasses;
-    }
-
-    /**
-     * Find all jars that have a plugin.properties file in the plugin folder.
-     * @return the list of all plugin entries, with their main class names and the jars files.
-     * @throws IOException thrown if reading the jar file fails
-     */
-    private ArrayList<PluginEntry> findPlugins() throws IOException {
-        ArrayList<PluginEntry> pluginEntries = new ArrayList<>();
-        File[] childFiles = path.listFiles();
-
-        if(childFiles == null) return pluginEntries;
-        for(File file : childFiles){
-            if(!file.isFile() || !file.getName().endsWith(".jar")) continue;
-            JarFile jarFile = new JarFile(file);
-            if(jarFile.getEntry("plugin.properties") == null) continue;
-            Properties properties = new Properties();
-            properties.load(jarFile.getInputStream(jarFile.getEntry("plugin.properties")));
-
-            PluginEntry entry = new PluginEntry();
-            entry.mainClass = properties.getProperty("mainClass");
-            entry.jarPath = file;
-            pluginEntries.add(entry);
-        }
-        return pluginEntries;
-    }
-
-    /**
-     * Loads all valid plugins and keeps track of them.
-     * @throws IOException thrown if loading from jar files fails.
-     * @throws ClassNotFoundException thrown if class specified in plugin.properties doesn't exist.
-     */
-    public void loadValidPlugins() throws IOException, ClassNotFoundException {
-        foundMainClasses = loadPluginClasses();
-    }
-
-    /**
-     * Gets the list of all the plugins that have last been loaded.
-     * @return the list of loaded class files.
-     */
-    public ArrayList<Class<?>> getFoundMainClasses() {
-        return foundMainClasses;
-    }
-
-}

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

@@ -15,29 +15,29 @@ public class PluginManager {
     /**
      * A list of loaded plugins.
      */
-    private ArrayList<Plugin> plugins;
+    private List<Plugin> plugins;
     /**
      * List of functions that have been cached,
      * that is, found in a plugin and returned.
      */
-    private HashMap<String, Function> cachedFunctions;
+    private Map<String, Function> cachedFunctions;
     /**
      * List of operators tha have been cached,
      * that is, found in a plugin and returned.
      */
-    private HashMap<String, Operator> cachedOperators;
+    private Map<String, Operator> cachedOperators;
     /**
      * List of all functions loaded by the plugins.
      */
-    private HashSet<String> allFunctions;
+    private Set<String> allFunctions;
     /**
      * List of all operators loaded by the plugins.
      */
-    private HashSet<String> allOperators;
+    private Set<String> allOperators;
     /**
      * The list of plugin listeners attached to this instance.
      */
-    private HashSet<PluginListener> listeners;
+    private Set<PluginListener> listeners;
 
     /**
      * Creates a new plugin manager.
@@ -155,7 +155,7 @@ public class PluginManager {
      * Gets all the functions loaded by the Plugin Manager.
      * @return the set of all functions that were loaded.
      */
-    public HashSet<String> getAllFunctions() {
+    public Set<String> getAllFunctions() {
         return allFunctions;
     }
 
@@ -163,7 +163,7 @@ public class PluginManager {
      * Gets all the operators loaded by the Plugin Manager.
      * @return the set of all operators that were loaded.
      */
-    public HashSet<String> getAllOperators() {
+    public Set<String> getAllOperators() {
         return allOperators;
     }
 

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

@@ -3,12 +3,10 @@ package org.nwapw.abacus.plugin;
 import org.nwapw.abacus.function.Function;
 import org.nwapw.abacus.function.Operator;
 import org.nwapw.abacus.function.OperatorAssociativity;
+import org.nwapw.abacus.function.OperatorType;
 import org.nwapw.abacus.number.NaiveNumber;
 import org.nwapw.abacus.number.NumberInterface;
 
-import javax.print.attribute.standard.MediaSize;
-import java.util.ArrayList;
-import java.util.HashMap;
 import java.util.function.BiFunction;
 
 /**
@@ -23,7 +21,7 @@ public class StandardPlugin extends Plugin {
 
     @Override
     public void onEnable() {
-        registerOperator("+", new Operator(OperatorAssociativity.LEFT, 0, new Function() {
+        registerOperator("+", new Operator(OperatorAssociativity.LEFT, OperatorType.BINARY_INFIX, 0, new Function() {
             @Override
             protected boolean matchesParams(NumberInterface[] params) {
                 return params.length >= 1;
@@ -39,7 +37,7 @@ public class StandardPlugin extends Plugin {
             }
         }));
 
-        registerOperator("-", new Operator(OperatorAssociativity.LEFT, 0, new Function() {
+        registerOperator("-", new Operator(OperatorAssociativity.LEFT, OperatorType.BINARY_INFIX, 0, new Function() {
             @Override
             protected boolean matchesParams(NumberInterface[] params) {
                 return params.length == 2;
@@ -51,7 +49,7 @@ public class StandardPlugin extends Plugin {
             }
         }));
 
-        registerOperator("*", new Operator(OperatorAssociativity.LEFT, 1, new Function() {
+        registerOperator("*", new Operator(OperatorAssociativity.LEFT, OperatorType.BINARY_INFIX,1, new Function() {
             @Override
             protected boolean matchesParams(NumberInterface[] params) {
                 return params.length >= 1;
@@ -67,7 +65,7 @@ public class StandardPlugin extends Plugin {
             }
         }));
 
-        registerOperator("/", new Operator(OperatorAssociativity.LEFT, 1, new Function() {
+        registerOperator("/", new Operator(OperatorAssociativity.LEFT, OperatorType.BINARY_INFIX,1, new Function() {
             @Override
             protected boolean matchesParams(NumberInterface[] params) {
                 return params.length == 2;
@@ -79,7 +77,7 @@ public class StandardPlugin extends Plugin {
             }
         }));
 
-        registerOperator("^", new Operator(OperatorAssociativity.RIGHT, 2, new Function() {
+        registerOperator("^", new Operator(OperatorAssociativity.RIGHT, OperatorType.BINARY_INFIX, 2, new Function() {
             @Override
             protected boolean matchesParams(NumberInterface[] params) {
                 return params.length == 2;
@@ -91,7 +89,7 @@ public class StandardPlugin extends Plugin {
             }
         }));
 
-        registerFunction("!", new Function() {
+        registerOperator("!", new Operator(OperatorAssociativity.RIGHT, OperatorType.UNARY_POSTFIX, 0, new Function() {
             //private HashMap<Class<? extends NumberInterface>, ArrayList<NumberInterface>> storedList = new HashMap<Class<? extends NumberInterface>, ArrayList<NumberInterface>>();
             @Override
             protected boolean matchesParams(NumberInterface[] params) {
@@ -116,7 +114,7 @@ public class StandardPlugin extends Plugin {
                     storedList.get(params[0].getClass()).add(NaiveNumber.ONE.promoteTo(params[0].getClass()));
                 }*/
             }
-        });
+        }));
 
         registerFunction("abs", new Function() {
             @Override
@@ -231,7 +229,7 @@ public class StandardPlugin extends Plugin {
 
             @Override
             protected NumberInterface applyInternal(NumberInterface[] params) {
-                return StandardPlugin.this.getFunction("pow").apply(params[0], (new NaiveNumber(0.5)));
+                return StandardPlugin.this.getOperator("^").getFunction().apply(params[0], (new NaiveNumber(0.5)));
             }
         });
     }
@@ -248,7 +246,7 @@ public class StandardPlugin extends Plugin {
      * @return the nth term of the series.
      */
     private NumberInterface getExpSeriesTerm(int n, NumberInterface x){
-        return x.intPow(n).divide(this.getFunction("!").apply((new NaiveNumber(n)).promoteTo(x.getClass())));
+        return x.intPow(n).divide(this.getOperator("!").getFunction().apply((new NaiveNumber(n)).promoteTo(x.getClass())));
     }
 
     /**

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

@@ -3,7 +3,7 @@ package org.nwapw.abacus.tree;
 /**
  * A tree node that represents an operation being applied to two operands.
  */
-public class OpNode extends TreeNode {
+public class BinaryInfixNode extends TreeNode {
 
     /**
      * The operation being applied.
@@ -18,14 +18,14 @@ public class OpNode extends TreeNode {
      */
     private TreeNode right;
 
-    private OpNode() {}
+    private BinaryInfixNode() {}
 
     /**
      * Creates a new operation node with the given operation
      * and no child nodes.
      * @param operation the operation.
      */
-    public OpNode(String operation){
+    public BinaryInfixNode(String operation){
         this(operation, null, null);
     }
 
@@ -36,7 +36,7 @@ public class OpNode extends TreeNode {
      * @param left the left node of the expression.
      * @param right the right node of the expression.
      */
-    public OpNode(String operation, TreeNode left, TreeNode right){
+    public BinaryInfixNode(String operation, TreeNode left, TreeNode right){
         this.operation = operation;
         this.left = left;
         this.right = right;

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

@@ -1,6 +1,7 @@
 package org.nwapw.abacus.tree;
 
 import java.util.ArrayList;
+import java.util.List;
 
 /**
  * A node that represents a function call.
@@ -14,7 +15,7 @@ public class FunctionNode extends TreeNode {
     /**
      * The list of arguments to the function.
      */
-    private ArrayList<TreeNode> children;
+    private List<TreeNode> children;
 
     /**
      * Creates a function node with no function.

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

@@ -27,12 +27,17 @@ 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 OpNode){
+        } else if(node instanceof BinaryInfixNode){
             NumberInterface left = (NumberInterface) children[0];
             NumberInterface right = (NumberInterface) children[1];
-            Function function = manager.operatorFor(((OpNode) node).getOperation()).getFunction();
+            Function function = manager.operatorFor(((BinaryInfixNode) node).getOperation()).getFunction();
             if(function == null) return null;
             return function.apply(left, right);
+        } else if(node instanceof UnaryPrefixNode) {
+            NumberInterface child = (NumberInterface) children[0];
+            Function functionn = manager.operatorFor(((UnaryPrefixNode) node).getOperation()).getFunction();
+            if(functionn == null) return null;
+            return functionn.apply(child);
         } else if(node instanceof FunctionNode){
             NumberInterface[] convertedChildren = new NumberInterface[children.length];
             for(int i = 0; i < convertedChildren.length; i++){

src/org/nwapw/abacus/tree/TreeBuilder.java

@@ -1,6 +1,7 @@
 package org.nwapw.abacus.tree;
 
 import org.nwapw.abacus.function.OperatorAssociativity;
+import org.nwapw.abacus.function.OperatorType;
 import org.nwapw.abacus.lexing.Lexer;
 import org.nwapw.abacus.lexing.pattern.Match;
 import org.nwapw.abacus.lexing.pattern.Pattern;
@@ -19,11 +20,15 @@ public class TreeBuilder {
     /**
      * The map of operator precedences.
      */
-    private HashMap<String, Integer> precedenceMap;
+    private Map<String, Integer> precedenceMap;
     /**
      * The map of operator associativity.
      */
-    private HashMap<String, OperatorAssociativity> associativityMap;
+    private Map<String, OperatorAssociativity> associativityMap;
+    /**
+     * The map of operator types.
+     */
+    private Map<String, OperatorType> typeMap;
 
     /**
      * Comparator used to sort token types.
@@ -43,6 +48,7 @@ public class TreeBuilder {
         }};
         precedenceMap = new HashMap<>();
         associativityMap = new HashMap<>();
+        typeMap = new HashMap<>();
     }
 
     /**
@@ -59,10 +65,12 @@ public class TreeBuilder {
      * @param precedence the precedence of the operator.
      * @param associativity the associativity of the operator.
      */
-    public void registerOperator(String operator, int precedence, OperatorAssociativity associativity){
+    public void registerOperator(String operator, OperatorAssociativity associativity,
+                                 OperatorType operatorType, int precedence){
         lexer.register(Pattern.sanitize(operator), TokenType.OP);
         precedenceMap.put(operator, precedence);
         associativityMap.put(operator, associativity);
+        typeMap.put(operator, operatorType);
     }
 
     /**
@@ -70,7 +78,7 @@ public class TreeBuilder {
      * @param string the string to tokenize.
      * @return the list of tokens produced.
      */
-    public ArrayList<Match<TokenType>> tokenize(String string){
+    public List<Match<TokenType>> tokenize(String string){
         return lexer.lexAll(string, 0, tokenSorter);
     }
 
@@ -80,7 +88,7 @@ public class TreeBuilder {
      * @param from the tokens to be rearranged.
      * @return the resulting list of rearranged tokens.
      */
-    public ArrayList<Match<TokenType>> intoPostfix(String source, ArrayList<Match<TokenType>> from){
+    public List<Match<TokenType>> intoPostfix(String source, List<Match<TokenType>> from){
         ArrayList<Match<TokenType>> output = new ArrayList<>();
         Stack<Match<TokenType>> tokenStack = new Stack<>();
         while(!from.isEmpty()){
@@ -93,9 +101,15 @@ public class TreeBuilder {
                 tokenStack.push(match);
             } else if(matchType == TokenType.OP){
                 String tokenString = source.substring(match.getFrom(), match.getTo());
+                OperatorType type = typeMap.get(tokenString);
                 int precedence = precedenceMap.get(tokenString);
                 OperatorAssociativity associativity = associativityMap.get(tokenString);
 
+                if(type == OperatorType.UNARY_POSTFIX){
+                    output.add(match);
+                    continue;
+                }
+
                 while(!tokenStack.empty()) {
                     Match<TokenType> otherMatch = tokenStack.peek();
                     TokenType otherMatchType = otherMatch.getType();
@@ -138,15 +152,23 @@ public class TreeBuilder {
      * @param matches the list of tokens from the source string.
      * @return the construct tree expression.
      */
-    public TreeNode fromStringRecursive(String source, ArrayList<Match<TokenType>> matches){
+    public TreeNode fromStringRecursive(String source, List<Match<TokenType>> matches){
         if(matches.size() == 0) return null;
         Match<TokenType> match = matches.remove(0);
         TokenType matchType = match.getType();
         if(matchType == TokenType.OP){
+            String operator = source.substring(match.getFrom(), match.getTo());
+            OperatorType type = typeMap.get(operator);
+            if(type == OperatorType.BINARY_INFIX){
                 TreeNode right = fromStringRecursive(source, matches);
                 TreeNode left = fromStringRecursive(source, matches);
                 if(left == null || right == null) return null;
-            else return new OpNode(source.substring(match.getFrom(), match.getTo()), left, right);
+                else return new BinaryInfixNode(operator, left, right);
+            } else {
+                TreeNode applyTo = fromStringRecursive(source, matches);
+                if(applyTo == null) return null;
+                else return new UnaryPrefixNode(operator, applyTo);
+            }
         } else if(matchType == TokenType.NUM){
             return new NumberNode(Double.parseDouble(source.substring(match.getFrom(), match.getTo())));
         } else if(matchType == TokenType.FUNCTION){
@@ -170,7 +192,7 @@ public class TreeBuilder {
      * @return the resulting tree.
      */
     public TreeNode fromString(String string){
-        ArrayList<Match<TokenType>> matches = tokenize(string);
+        List<Match<TokenType>> matches = tokenize(string);
         if(matches == null) return null;
         matches.removeIf(m -> m.getType() == TokenType.WHITESPACE);
         matches = intoPostfix(string, matches);

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

@@ -0,0 +1,54 @@
+package org.nwapw.abacus.tree;
+
+public class UnaryPrefixNode extends TreeNode {
+
+    /**
+     * The operation this node will apply.
+     */
+    private String operation;
+    /**
+     * The tree node to apply the operation to.
+     */
+    private TreeNode applyTo;
+
+    /**
+     * Creates a new node with the given operation and no child.
+     * @param operation the operation for this node.
+     */
+    public UnaryPrefixNode(String operation){
+        this(operation, null);
+    }
+
+    /**
+     * Creates a new node with the given operation and child.
+     * @param operation the operation for this node.
+     * @param applyTo the node to apply the function to.
+     */
+    public UnaryPrefixNode(String operation, TreeNode applyTo){
+        this.operation = operation;
+        this.applyTo = applyTo;
+    }
+
+    @Override
+    public <T> T reduce(Reducer<T> reducer) {
+        Object reducedChild = applyTo.reduce(reducer);
+        if(reducedChild == null) return null;
+        return reducer.reduceNode(this, reducedChild);
+    }
+
+    /**
+     * Gets the operation of this node.
+     * @return the operation this node performs.
+     */
+    public String getOperation() {
+        return operation;
+    }
+
+    /**
+     * Gets the node to which this node's operation applies.
+     * @return the tree node to which the operation will be applied.
+     */
+    public TreeNode getApplyTo() {
+        return applyTo;
+    }
+}

src/org/nwapw/abacus/window/HistoryTableModel.java

@@ -6,6 +6,7 @@ import javax.swing.event.TableModelListener;
 import javax.swing.table.AbstractTableModel;
 import javax.swing.table.TableModel;
 import java.util.ArrayList;
+import java.util.List;
 
 /**
  * A table model to store data about the history of inputs
@@ -57,7 +58,7 @@ public class HistoryTableModel extends AbstractTableModel {
     /**
      * The list of entries.
      */
-    ArrayList<HistoryEntry> entries;
+    List<HistoryEntry> entries;
 
     /**
      * Creates a new empty history table model

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

@@ -269,7 +269,10 @@ public class Window extends JFrame implements PluginListener {
         }
         for(String operator : manager.getAllOperators()){
             Operator operatorObject = manager.operatorFor(operator);
-            builder.registerOperator(operator, operatorObject.getPrecedence(), operatorObject.getAssociativity());
+            builder.registerOperator(operator,
+                    operatorObject.getAssociativity(),
+                    operatorObject.getType(),
+                    operatorObject.getPrecedence());
         }
     }