Merge branch 'master' into plugin-conversions

Fix crash when a TreeValueFunction doesn't have documentation loaded.

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

@@ -1,9 +1,8 @@
 package org.nwapw.abacus.lexing;
 
-import org.nwapw.abacus.lexing.pattern.EndNode;
-import org.nwapw.abacus.lexing.pattern.Match;
 import org.nwapw.abacus.lexing.pattern.Pattern;
-import org.nwapw.abacus.lexing.pattern.PatternNode;
+import org.nwapw.abacus.lexing.pattern.nodes.EndNode;
+import org.nwapw.abacus.lexing.pattern.nodes.PatternNode;
 
 import java.util.*;
 
@@ -80,10 +79,10 @@ public class Lexer<T> {
 
             index++;
         }
-        matches.sort((a, b) -> compare.compare(a.getType(), b.getType()));
         if (compare != null) {
-            matches.sort(Comparator.comparingInt(a -> a.getContent().length()));
+            Collections.sort(matches, (a, b) -> compare.compare(a.getType(), b.getType()));
         }
+        Collections.sort(matches, (o1, o2) -> o1.getContent().length() - o2.getContent().length());
         return matches.isEmpty() ? null : matches.get(matches.size() - 1);
     }
 
@@ -137,7 +136,10 @@ public class Lexer<T> {
 
         @Override
         public int hashCode() {
-            return Objects.hash(name, id);
+            return Arrays.hashCode(new Object[] {
+                    this.name,
+                    this.id
+            });
         }
 
         @Override

core/src/main/java/org/nwapw/abacus/lexing/Match.java

@@ -1,4 +1,4 @@
-package org.nwapw.abacus.lexing.pattern;
+package org.nwapw.abacus.lexing;
 
 /**
  * A match that has been generated by the lexer.

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

@@ -1,10 +1,11 @@
 package org.nwapw.abacus.lexing.pattern;
 
+import org.nwapw.abacus.lexing.pattern.nodes.*;
+
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Stack;
-import java.util.function.Function;
 
 /**
  * A pattern that can be compiled from a string and used in lexing.
@@ -34,8 +35,8 @@ public class Pattern<T> {
      * A map of regex operator to functions that modify a PatternChain
      * with the appropriate operation.
      */
-    private Map<Character, Function<PatternChain<T>, PatternChain<T>>> operations =
+    private Map<Character, Transformation<T>> operations =
-            new HashMap<Character, Function<PatternChain<T>, PatternChain<T>>>() {{
+            new HashMap<Character, Transformation<T>>() {{
                 put('+', Pattern.this::transformPlus);
                 put('*', Pattern.this::transformStar);
                 put('?', Pattern.this::transformQuestion);
@@ -88,7 +89,7 @@ public class Pattern<T> {
      * @return the modified chain.
      */
     private PatternChain<T> transformPlus(PatternChain<T> chain) {
-        chain.tail.outputStates.add(chain.head);
+        chain.tail.getOutputStates().add(chain.head);
         return chain;
     }
 
@@ -102,10 +103,10 @@ public class Pattern<T> {
     private PatternChain<T> transformStar(PatternChain<T> chain) {
         LinkNode<T> newTail = new LinkNode<>();
         LinkNode<T> newHead = new LinkNode<>();
-        newHead.outputStates.add(chain.head);
+        newHead.getOutputStates().add(chain.head);
-        newHead.outputStates.add(newTail);
+        newHead.getOutputStates().add(newTail);
-        chain.tail.outputStates.add(newTail);
+        chain.tail.getOutputStates().add(newTail);
-        newTail.outputStates.add(newHead);
+        newTail.getOutputStates().add(newHead);
         chain.head = newHead;
         chain.tail = newTail;
         return chain;
@@ -121,9 +122,9 @@ public class Pattern<T> {
     private PatternChain<T> transformQuestion(PatternChain<T> chain) {
         LinkNode<T> newTail = new LinkNode<>();
         LinkNode<T> newHead = new LinkNode<>();
-        newHead.outputStates.add(chain.head);
+        newHead.getOutputStates().add(chain.head);
-        newHead.outputStates.add(newTail);
+        newHead.getOutputStates().add(newTail);
-        chain.tail.outputStates.add(newTail);
+        chain.tail.getOutputStates().add(newTail);
         chain.head = newHead;
         chain.tail = newTail;
         return chain;
@@ -140,8 +141,8 @@ public class Pattern<T> {
         LinkNode<T> tail = new LinkNode<>();
         PatternChain<T> newChain = new PatternChain<>(head, tail);
         for (PatternChain<T> chain : collection) {
-            head.outputStates.add(chain.head);
+            head.getOutputStates().add(chain.head);
-            chain.tail.outputStates.add(tail);
+            chain.tail.getOutputStates().add(tail);
         }
         return newChain;
     }
@@ -205,7 +206,7 @@ public class Pattern<T> {
             if (operations.containsKey(currentChar)) {
                 if (currentChain == null) return null;
 
-                currentChain = operations.get(currentChar).apply(currentChain);
+                currentChain = operations.get(currentChar).transform(currentChain);
                 fullChain.append(currentChain);
                 currentChain = null;
                 index++;

core/src/main/java/org/nwapw/abacus/lexing/pattern/PatternChain.java

@@ -1,5 +1,7 @@
 package org.nwapw.abacus.lexing.pattern;
 
+import org.nwapw.abacus.lexing.pattern.nodes.PatternNode;
+
 /**
  * A chain of nodes that can be treated as a single unit.
  * Used during pattern compilation.
@@ -56,7 +58,7 @@ public class PatternChain<T> {
             this.head = other.head;
             this.tail = other.tail;
         } else {
-            tail.outputStates.add(other.head);
+            tail.getOutputStates().add(other.head);
             tail = other.tail;
         }
     }
@@ -72,7 +74,7 @@ public class PatternChain<T> {
         if (tail == null) {
             head = tail = node;
         } else {
-            tail.outputStates.add(node);
+            tail.getOutputStates().add(node);
             tail = node;
         }
     }

core/src/main/java/org/nwapw/abacus/lexing/pattern/Transformation.java

@@ -0,0 +1,16 @@
+package org.nwapw.abacus.lexing.pattern;
+
+/**
+ * An interface that transforms a pattern chain into a different pattern chain.
+ * @param <T> the type used to identify the nodes in the pattern chain.
+ */
+public interface Transformation<T> {
+
+    /**
+     * Performs the actual transformation.
+     * @param from the original chain.
+     * @return the resulting chain.
+     */
+    PatternChain<T> transform(PatternChain<T> from);
+
+}

core/src/main/java/org/nwapw/abacus/lexing/pattern/nodes/AnyNode.java

@@ -1,4 +1,4 @@
-package org.nwapw.abacus.lexing.pattern;
+package org.nwapw.abacus.lexing.pattern.nodes;
 
 /**
  * A pattern node that matches any character.

core/src/main/java/org/nwapw/abacus/lexing/pattern/nodes/EndNode.java

@@ -1,4 +1,4 @@
-package org.nwapw.abacus.lexing.pattern;
+package org.nwapw.abacus.lexing.pattern.nodes;
 
 /**
  * A node that represents a successful match.

core/src/main/java/org/nwapw/abacus/lexing/pattern/nodes/LinkNode.java

@@ -1,4 +1,4 @@
-package org.nwapw.abacus.lexing.pattern;
+package org.nwapw.abacus.lexing.pattern.nodes;
 
 import java.util.Collection;
 

core/src/main/java/org/nwapw/abacus/lexing/pattern/nodes/PatternNode.java

@@ -1,4 +1,4 @@
-package org.nwapw.abacus.lexing.pattern;
+package org.nwapw.abacus.lexing.pattern.nodes;
 
 import java.util.Collection;
 import java.util.HashSet;
@@ -65,4 +65,11 @@ public class PatternNode<T> {
         outputStates.forEach(e -> e.addInto(into));
     }
 
+    /**
+     * Gets the output states of this node.
+     * @return the output states.
+     */
+    public Set<PatternNode<T>> getOutputStates() {
+        return outputStates;
+    }
 }

core/src/main/java/org/nwapw/abacus/lexing/pattern/nodes/RangeNode.java

@@ -1,4 +1,4 @@
-package org.nwapw.abacus.lexing.pattern;
+package org.nwapw.abacus.lexing.pattern.nodes;
 
 /**
  * A node that matches a range of characters.

core/src/main/java/org/nwapw/abacus/lexing/pattern/nodes/ValueNode.java

@@ -1,4 +1,4 @@
-package org.nwapw.abacus.lexing.pattern;
+package org.nwapw.abacus.lexing.pattern.nodes;
 
 /**
  * A node that matches a single value.

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

@@ -1,4 +1,6 @@
-package org.nwapw.abacus.number;
+package org.nwapw.abacus.number.standard;
+
+import org.nwapw.abacus.number.NumberInterface;
 
 /**
  * An implementation of NumberInterface using a double.

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

@@ -1,4 +1,6 @@
-package org.nwapw.abacus.number;
+package org.nwapw.abacus.number.standard;
+
+import org.nwapw.abacus.number.NumberInterface;
 
 import java.math.BigDecimal;
 import java.math.MathContext;

core/src/main/java/org/nwapw/abacus/parsing/Tokenizer.java

@@ -1,20 +0,0 @@
-package org.nwapw.abacus.parsing;
-
-import java.util.List;
-
-/**
- * Interface that provides the ability to convert a string into a list of tokens.
- *
- * @param <T> the type of the tokens produced.
- */
-public interface Tokenizer<T> {
-
-    /**
-     * Converts a string into tokens.
-     *
-     * @param string the string to convert.
-     * @return the list of tokens, or null on error.
-     */
-    public List<T> tokenizeString(String string);
-
-}

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

@@ -1,48 +0,0 @@
-package org.nwapw.abacus.parsing;
-
-import org.nwapw.abacus.tree.TreeNode;
-
-import java.util.List;
-
-/**
- * TreeBuilder class used to piece together a Tokenizer and
- * Parser of the same kind. This is used to essentially avoid
- * working with any parameters at all, and the generics
- * in this class are used only to ensure the tokenizer and parser
- * are of the same type.
- *
- * @param <T> the type of tokens created by the tokenizer and used by the parser.
- */
-public class TreeBuilder<T> {
-
-    /**
-     * The tokenizer used to convert a string into tokens.
-     */
-    private Tokenizer<T> tokenizer;
-    /**
-     * The parser used to parse a list of tokens into a tree.
-     */
-    private Parser<T> parser;
-
-    /**
-     * Create a new Tree Builder with the given tokenizer and parser
-     *
-     * @param tokenizer the tokenizer to turn strings into tokens
-     * @param parser    the parser to turn tokens into a tree
-     */
-    public TreeBuilder(Tokenizer<T> tokenizer, Parser<T> parser) {
-        this.tokenizer = tokenizer;
-        this.parser = parser;
-    }
-
-    /**
-     * Parse the given string into a tree.
-     *
-     * @param input the string to parse into a tree.
-     * @return the resulting tree.
-     */
-    public TreeNode fromString(String input) {
-        return parser.constructTree(tokenizer.tokenizeString(input));
-    }
-
-}

core/src/main/java/org/nwapw/abacus/parsing/standard/LexerTokenizer.java

@@ -1,12 +1,12 @@
-package org.nwapw.abacus.parsing;
+package org.nwapw.abacus.parsing.standard;
 
 import org.nwapw.abacus.exception.TokenizeException;
 import org.nwapw.abacus.lexing.Lexer;
-import org.nwapw.abacus.lexing.pattern.Match;
+import org.nwapw.abacus.lexing.Match;
 import org.nwapw.abacus.lexing.pattern.Pattern;
+import org.nwapw.abacus.parsing.Tokenizer;
 import org.nwapw.abacus.plugin.PluginListener;
 import org.nwapw.abacus.plugin.PluginManager;
-import org.nwapw.abacus.tree.TokenType;
 
 import java.util.Comparator;
 import java.util.List;
@@ -20,7 +20,7 @@ public class LexerTokenizer implements Tokenizer<Match<TokenType>>, PluginListen
     /**
      * Comparator used to sort the tokens produced by the lexer.
      */
-    protected static final Comparator<TokenType> TOKEN_SORTER = Comparator.comparingInt(e -> e.priority);
+    protected static final Comparator<TokenType> TOKEN_SORTER = (o1, o2) -> o1.priority - o2.priority;
 
     /**
      * The lexer instance used to turn strings into matches.

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

@@ -1,13 +1,14 @@
-package org.nwapw.abacus.parsing;
+package org.nwapw.abacus.parsing.standard;
 
 import org.nwapw.abacus.exception.ParseException;
 import org.nwapw.abacus.function.Operator;
 import org.nwapw.abacus.function.OperatorAssociativity;
 import org.nwapw.abacus.function.OperatorType;
-import org.nwapw.abacus.lexing.pattern.Match;
+import org.nwapw.abacus.lexing.Match;
+import org.nwapw.abacus.parsing.Parser;
 import org.nwapw.abacus.plugin.PluginListener;
 import org.nwapw.abacus.plugin.PluginManager;
-import org.nwapw.abacus.tree.*;
+import org.nwapw.abacus.tree.nodes.*;
 
 import java.util.*;
 
@@ -124,7 +125,7 @@ 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<? extends Match<TokenType>> matches) {
         if (matches.size() == 0) throw new ParseException("no tokens left in input");
         Match<TokenType> match = matches.remove(0);
         TokenType matchType = match.getType();
@@ -162,7 +163,7 @@ public class ShuntingYardParser implements Parser<Match<TokenType>>, PluginListe
             matches.remove(0);
             CallNode node;
             if (matchType == TokenType.FUNCTION) {
-                node = new FunctionNode(functionName, children);
+                node = new NumberFunctionNode(functionName, children);
             } else {
                 node = new TreeValueFunctionNode(functionName, children);
             }
@@ -172,7 +173,7 @@ public class ShuntingYardParser implements Parser<Match<TokenType>>, PluginListe
     }
 
     @Override
-    public TreeNode constructTree(List<Match<TokenType>> tokens) {
+    public TreeNode constructTree(List<? extends Match<TokenType>> tokens) {
         if (tokens.isEmpty()) throw new ParseException("no input tokens");
         tokens = intoPostfix(new ArrayList<>(tokens));
         Collections.reverse(tokens);

core/src/main/java/org/nwapw/abacus/parsing/standard/TokenType.java

@@ -1,4 +1,4 @@
-package org.nwapw.abacus.tree;
+package org.nwapw.abacus.parsing.standard;
 
 /**
  * Enum to represent the type of the token that has been matched

core/src/main/java/org/nwapw/abacus/plugin/NumberImplementation.java

@@ -1,10 +1,10 @@
 package org.nwapw.abacus.plugin;
 
 import org.nwapw.abacus.number.NumberInterface;
+import org.nwapw.abacus.number.promotion.PromotionFunction;
 
 import java.util.HashMap;
 import java.util.Map;
-import java.util.function.Function;
 
 /**
  * A class that holds data about a number implementation.
@@ -14,7 +14,7 @@ public abstract class NumberImplementation {
     /**
      * The list of paths through which this implementation can be promoted.
      */
-    private Map<String, Function<NumberInterface, NumberInterface>> promotionPaths;
+    private Map<String, PromotionFunction> promotionPaths;
     /**
      * The implementation class for this implementation.
      */
@@ -41,7 +41,7 @@ public abstract class NumberImplementation {
      *
      * @return the map of documentation paths.
      */
-    public final Map<String, Function<NumberInterface, NumberInterface>> getPromotionPaths() {
+    public final Map<String, PromotionFunction> getPromotionPaths() {
         return promotionPaths;
     }
 

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

@@ -1,6 +1,11 @@
 package org.nwapw.abacus.plugin;
 
-import org.nwapw.abacus.function.*;
+import org.nwapw.abacus.function.Documentation;
+import org.nwapw.abacus.function.DocumentationType;
+import org.nwapw.abacus.function.interfaces.NumberFunction;
+import org.nwapw.abacus.function.interfaces.NumberOperator;
+import org.nwapw.abacus.function.interfaces.TreeValueFunction;
+import org.nwapw.abacus.function.interfaces.TreeValueOperator;
 import org.nwapw.abacus.number.NumberInterface;
 
 /**

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

@@ -1,7 +1,12 @@
 package org.nwapw.abacus.plugin;
 
 import org.nwapw.abacus.Abacus;
-import org.nwapw.abacus.function.*;
+import org.nwapw.abacus.function.Documentation;
+import org.nwapw.abacus.function.DocumentationType;
+import org.nwapw.abacus.function.interfaces.NumberFunction;
+import org.nwapw.abacus.function.interfaces.NumberOperator;
+import org.nwapw.abacus.function.interfaces.TreeValueFunction;
+import org.nwapw.abacus.function.interfaces.TreeValueOperator;
 import org.nwapw.abacus.number.NumberInterface;
 
 import java.lang.reflect.InvocationTargetException;

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

@@ -1,12 +1,18 @@
-package org.nwapw.abacus.plugin;
+package org.nwapw.abacus.plugin.standard;
 
 import org.nwapw.abacus.context.MutableEvaluationContext;
-import org.nwapw.abacus.function.*;
+import org.nwapw.abacus.function.Documentation;
-import org.nwapw.abacus.number.NaiveNumber;
+import org.nwapw.abacus.function.DocumentationType;
+import org.nwapw.abacus.function.interfaces.NumberFunction;
+import org.nwapw.abacus.function.interfaces.NumberOperator;
+import org.nwapw.abacus.function.interfaces.TreeValueOperator;
 import org.nwapw.abacus.number.NumberInterface;
-import org.nwapw.abacus.number.PreciseNumber;
+import org.nwapw.abacus.number.standard.NaiveNumber;
-import org.nwapw.abacus.tree.TreeNode;
+import org.nwapw.abacus.number.standard.PreciseNumber;
-import org.nwapw.abacus.tree.VariableNode;
+import org.nwapw.abacus.plugin.NumberImplementation;
+import org.nwapw.abacus.plugin.Plugin;
+import org.nwapw.abacus.plugin.PluginManager;
+import org.nwapw.abacus.plugin.standard.operator.*;
 
 import java.util.ArrayList;
 import java.util.HashMap;
@@ -20,93 +26,27 @@ public class StandardPlugin extends Plugin {
     /**
      * The set operator.
      */
-    public final TreeValueOperator opSet = new TreeValueOperator(OperatorAssociativity.LEFT, OperatorType.BINARY_INFIX, 0) {
+    public static final TreeValueOperator OP_SET = new OperatorSet();
-        @Override
-        public boolean matchesParams(MutableEvaluationContext context, TreeNode[] params) {
-            return params.length == 2 && params[0] instanceof VariableNode;
-        }
-
-        @Override
-        public NumberInterface applyInternal(MutableEvaluationContext context, TreeNode[] params) {
-            String assignTo = ((VariableNode) params[0]).getVariable();
-            NumberInterface value = params[1].reduce(context.getInheritedReducer());
-            context.setVariable(assignTo, value);
-            return value;
-        }
-    };
     /**
      * The define operator.
      */
-    public final TreeValueOperator opDefine = new TreeValueOperator(OperatorAssociativity.LEFT, OperatorType.BINARY_INFIX, 0) {
+    public final TreeValueOperator OP_DEFINE = new OperatorDefine();
-        @Override
-        public boolean matchesParams(MutableEvaluationContext context, TreeNode[] params) {
-            return params.length == 2 && params[0] instanceof VariableNode;
-        }
-
-        @Override
-        public NumberInterface applyInternal(MutableEvaluationContext context, TreeNode[] params) {
-            String assignTo = ((VariableNode) params[0]).getVariable();
-            context.setDefinition(assignTo, params[1]);
-            return params[1].reduce(context.getInheritedReducer());
-        }
-    };
     /**
      * The addition operator, +
      */
-    public static final NumberOperator OP_ADD = new NumberOperator(OperatorAssociativity.LEFT, OperatorType.BINARY_INFIX, 0) {
+    public static final NumberOperator OP_ADD = new OperatorAdd();
-        @Override
-        public boolean matchesParams(MutableEvaluationContext context, NumberInterface[] params) {
-            return params.length == 2;
-        }
-
-        @Override
-        public NumberInterface applyInternal(MutableEvaluationContext context, NumberInterface[] params) {
-            return params[0].add(params[1]);
-        }
-    };
     /**
      * The subtraction operator, -
      */
-    public static final NumberOperator OP_SUBTRACT = new NumberOperator(OperatorAssociativity.LEFT, OperatorType.BINARY_INFIX, 0) {
+    public static final NumberOperator OP_SUBTRACT = new OperatorSubtract();
-        @Override
-        public boolean matchesParams(MutableEvaluationContext context, NumberInterface[] params) {
-            return params.length == 2;
-        }
-
-        @Override
-        public NumberInterface applyInternal(MutableEvaluationContext context, NumberInterface[] params) {
-            return params[0].subtract(params[1]);
-
-        }
-    };
     /**
      * The negation operator, -
      */
-    public static final NumberOperator OP_NEGATE = new NumberOperator(OperatorAssociativity.LEFT, OperatorType.UNARY_PREFIX, 0) {
+    public static final NumberOperator OP_NEGATE = new OperatorNegate();
-        @Override
-        public boolean matchesParams(MutableEvaluationContext context, NumberInterface[] params) {
-            return params.length == 1;
-        }
-
-        @Override
-        public NumberInterface applyInternal(MutableEvaluationContext context, NumberInterface[] params) {
-            return params[0].negate();
-        }
-    };
     /**
      * The multiplication operator, *
      */
-    public static final NumberOperator OP_MULTIPLY = new NumberOperator(OperatorAssociativity.LEFT, OperatorType.BINARY_INFIX, 1) {
+    public static final NumberOperator OP_MULTIPLY = new OperatorMultiply();
-        @Override
-        public boolean matchesParams(MutableEvaluationContext context, NumberInterface[] params) {
-            return params.length == 2;
-        }
-
-        @Override
-        public NumberInterface applyInternal(MutableEvaluationContext context, NumberInterface[] params) {
-            return params[0].multiply(params[1]);
-        }
-    };
     /**
      * The implementation for double-based naive numbers.
      */
@@ -161,96 +101,19 @@ public class StandardPlugin extends Plugin {
     /**
      * The division operator, /
      */
-    public static final NumberOperator OP_DIVIDE = new NumberOperator(OperatorAssociativity.LEFT, OperatorType.BINARY_INFIX, 1) {
+    public static final NumberOperator OP_DIVIDE = new OperatorDivide();
-        @Override
-        public boolean matchesParams(MutableEvaluationContext context, NumberInterface[] params) {
-            return params.length == 2 && params[1].compareTo(context.getInheritedNumberImplementation().instanceForString(Integer.toString(0))) != 0;
-        }
-
-        @Override
-        public NumberInterface applyInternal(MutableEvaluationContext context, NumberInterface[] params) {
-            return params[0].divide(params[1]);
-        }
-    };
     /**
      * The factorial operator, !
      */
-    public static final NumberOperator OP_FACTORIAL = new NumberOperator(OperatorAssociativity.RIGHT, OperatorType.UNARY_POSTFIX, 0) {
+    public static final NumberOperator OP_FACTORIAL = new OperatorFactorial();
-        //private HashMap<Class<? extends NumberInterface>, ArrayList<NumberInterface>> storedList = new HashMap<Class<? extends NumberInterface>, ArrayList<NumberInterface>>();
-        @Override
-        public boolean matchesParams(MutableEvaluationContext context, NumberInterface[] params) {
-            return params.length == 1
-                    && params[0].fractionalPart().compareTo(context.getInheritedNumberImplementation().instanceForString("0")) == 0
-                    && params[0].signum() >= 0;
-        }
-
-        @Override
-        public NumberInterface applyInternal(MutableEvaluationContext context, NumberInterface[] params) {
-            NumberImplementation implementation = context.getInheritedNumberImplementation();
-            if (params[0].signum() == 0) {
-                return implementation.instanceForString("1");
-            }
-            NumberInterface one = implementation.instanceForString("1");
-            NumberInterface factorial = params[0];
-            NumberInterface multiplier = params[0];
-            //It is necessary to later prevent calls of factorial on anything but non-negative integers.
-            while ((multiplier = multiplier.subtract(one)).signum() == 1) {
-                factorial = factorial.multiply(multiplier);
-            }
-            return factorial;
-                /*if(!storedList.containsKey(params[0].getClass())){
-                    storedList.put(params[0].getClass(), new ArrayList<NumberInterface>());
-                    storedList.get(params[0].getClass()).add(NaiveNumber.ONE.promoteTo(params[0].getClass()));
-                    storedList.get(params[0].getClass()).add(NaiveNumber.ONE.promoteTo(params[0].getClass()));
-                }*/
-        }
-    };
     /**
      * The permutation operator.
      */
-    public static final NumberOperator OP_NPR = new NumberOperator(OperatorAssociativity.RIGHT, OperatorType.BINARY_INFIX, 0) {
+    public static final NumberOperator OP_NPR = new OperatorNpr();
-        @Override
-        public boolean matchesParams(MutableEvaluationContext context, NumberInterface[] params) {
-            return params.length == 2 && params[0].fractionalPart().signum() == 0
-                    && params[1].fractionalPart().signum() == 0;
-        }
-
-        @Override
-        public NumberInterface applyInternal(MutableEvaluationContext context, NumberInterface[] params) {
-            NumberImplementation implementation = context.getInheritedNumberImplementation();
-            if (params[0].compareTo(params[1]) < 0 ||
-                    params[0].signum() < 0 ||
-                    (params[0].signum() == 0 && params[1].signum() != 0)) return implementation.instanceForString("0");
-            NumberInterface total = implementation.instanceForString("1");
-            NumberInterface multiplyBy = params[0];
-            NumberInterface remainingMultiplications = params[1];
-            NumberInterface halfway = params[0].divide(implementation.instanceForString("2"));
-            if (remainingMultiplications.compareTo(halfway) > 0) {
-                remainingMultiplications = params[0].subtract(remainingMultiplications);
-            }
-            while (remainingMultiplications.signum() > 0) {
-                total = total.multiply(multiplyBy);
-                remainingMultiplications = remainingMultiplications.subtract(implementation.instanceForString("1"));
-                multiplyBy = multiplyBy.subtract(implementation.instanceForString("1"));
-            }
-            return total;
-        }
-    };
     /**
      * The combination operator.
      */
-    public static final NumberOperator OP_NCR = new NumberOperator(OperatorAssociativity.RIGHT, OperatorType.BINARY_INFIX, 0) {
+    public static final NumberOperator OP_NCR = new OperatorNcr();
-        @Override
-        public boolean matchesParams(MutableEvaluationContext context, NumberInterface[] params) {
-            return params.length == 2 && params[0].fractionalPart().signum() == 0
-                    && params[1].fractionalPart().signum() == 0;
-        }
-
-        @Override
-        public NumberInterface applyInternal(MutableEvaluationContext context, NumberInterface[] params) {
-            return OP_NPR.apply(context, params).divide(OP_FACTORIAL.apply(context, params[1]));
-        }
-    };
     /**
      * The absolute value function, abs(-3) = 3
      */
@@ -363,34 +226,7 @@ public class StandardPlugin extends Plugin {
     /**
      * The caret / pow operator, ^
      */
-    public static final NumberOperator OP_CARET = new NumberOperator(OperatorAssociativity.RIGHT, OperatorType.BINARY_INFIX, 2) {
+    public static final NumberOperator OP_CARET = new OperatorCaret();
-        @Override
-        public boolean matchesParams(MutableEvaluationContext context, NumberInterface[] params) {
-            NumberInterface zero = context.getInheritedNumberImplementation().instanceForString("0");
-            return params.length == 2
-                    && !(params[0].compareTo(zero) == 0
-                    && params[1].compareTo(zero) == 0)
-                    && !(params[0].signum() == -1 && params[1].fractionalPart().compareTo(zero) != 0);
-        }
-
-        @Override
-        public NumberInterface applyInternal(MutableEvaluationContext context, NumberInterface[] params) {
-            NumberImplementation implementation = context.getInheritedNumberImplementation();
-            NumberInterface zero = implementation.instanceForString("0");
-            if (params[0].compareTo(zero) == 0)
-                return zero;
-            else if (params[1].compareTo(zero) == 0)
-                return implementation.instanceForString("1");
-            //Detect integer bases:
-            if (params[0].fractionalPart().compareTo(implementation.instanceForString("0")) == 0
-                    && FUNCTION_ABS.apply(context, params[1]).compareTo(implementation.instanceForString(Integer.toString(Integer.MAX_VALUE))) < 0
-                    && FUNCTION_ABS.apply(context, params[1]).compareTo(implementation.instanceForString("1")) >= 0) {
-                NumberInterface[] newParams = {params[0], params[1].fractionalPart()};
-                return params[0].intPow(params[1].floor().intValue()).multiply(applyInternal(context, newParams));
-            }
-            return FUNCTION_EXP.apply(context, FUNCTION_LN.apply(context, FUNCTION_ABS.apply(context, params[0])).multiply(params[1]));
-        }
-    };
     /**
      * The square root function.
      */
@@ -756,8 +592,8 @@ public class StandardPlugin extends Plugin {
         registerOperator("^", OP_CARET);
         registerOperator("!", OP_FACTORIAL);
 
-        registerTreeValueOperator("=", opSet);
+        registerTreeValueOperator("=", OP_SET);
-        registerTreeValueOperator(":=", opDefine);
+        registerTreeValueOperator(":=", OP_DEFINE);
 
         registerOperator("nPr", OP_NPR);
         registerOperator("nCr", OP_NCR);

core/src/main/kotlin/org/nwapw/abacus/Abacus.kt

@@ -1,17 +1,15 @@
 package org.nwapw.abacus
 
 import org.nwapw.abacus.config.Configuration
-import org.nwapw.abacus.context.MutableEvaluationContext
 import org.nwapw.abacus.context.EvaluationContext
-import org.nwapw.abacus.number.PromotionManager
+import org.nwapw.abacus.context.MutableEvaluationContext
-import org.nwapw.abacus.parsing.LexerTokenizer
+import org.nwapw.abacus.number.promotion.PromotionManager
-import org.nwapw.abacus.parsing.ShuntingYardParser
 import org.nwapw.abacus.parsing.TreeBuilder
+import org.nwapw.abacus.parsing.standard.LexerTokenizer
+import org.nwapw.abacus.parsing.standard.ShuntingYardParser
 import org.nwapw.abacus.plugin.PluginManager
-import org.nwapw.abacus.plugin.StandardPlugin
+import org.nwapw.abacus.plugin.standard.StandardPlugin
-import org.nwapw.abacus.tree.EvaluationResult
+import org.nwapw.abacus.tree.nodes.TreeNode
-import org.nwapw.abacus.tree.NumberReducer
-import org.nwapw.abacus.tree.TreeNode
 
 /**
  * Core class to handle all mathematics.
@@ -48,7 +46,7 @@ class Abacus(val configuration: Configuration) {
     /**
      * The hidden, mutable implementation of the context.
      */
-    private val mutableContext = MutableEvaluationContext(numberImplementation = StandardPlugin.IMPLEMENTATION_NAIVE)
+    private val mutableContext = MutableEvaluationContext(numberImplementation = StandardPlugin.IMPLEMENTATION_NAIVE, abacus = this)
     /**
      * The base context from which calculations are started.
      */
@@ -107,9 +105,8 @@ class Abacus(val configuration: Configuration) {
      * @return the evaluation result.
      */
     fun evaluateTreeWithContext(tree: TreeNode, context: MutableEvaluationContext): EvaluationResult {
-        val newReducer = NumberReducer(this, context)
+        val evaluationValue = tree.reduce(context)
-        val evaluationValue = tree.reduce(newReducer)
+        return EvaluationResult(evaluationValue, context)
-        return EvaluationResult(evaluationValue, newReducer.context)
     }
 
 }

core/src/main/kotlin/org/nwapw/abacus/EvaluationResult.kt

@@ -1,4 +1,4 @@
-package org.nwapw.abacus.tree
+package org.nwapw.abacus
 
 import org.nwapw.abacus.context.MutableEvaluationContext
 import org.nwapw.abacus.number.NumberInterface

core/src/main/kotlin/org/nwapw/abacus/context/EvaluationContext.kt

@@ -1,9 +1,10 @@
 package org.nwapw.abacus.context
 
+import org.nwapw.abacus.Abacus
 import org.nwapw.abacus.number.NumberInterface
 import org.nwapw.abacus.plugin.NumberImplementation
 import org.nwapw.abacus.tree.Reducer
-import org.nwapw.abacus.tree.TreeNode
+import org.nwapw.abacus.tree.nodes.TreeNode
 
 /**
  * A context for the reduction of a [org.nwapw.abacus.tree.TreeNode] into a number.
@@ -13,11 +14,11 @@ import org.nwapw.abacus.tree.TreeNode
  *
  * @property parent the parent of this context.
  * @property numberImplementation the implementation for numbers of this context.
- * @property reducer the reducer used by this context.
+ * @property abacus the abacus instance used by this reducer.
  */
-open class EvaluationContext(val parent: EvaluationContext? = null,
+abstract class EvaluationContext(val parent: EvaluationContext? = null,
-                             open val numberImplementation: NumberImplementation? = null,
+                                 open val numberImplementation: NumberImplementation? = null,
-                             open val reducer: Reducer<NumberInterface>? = null) {
+                                 open val abacus: Abacus? = null): Reducer<NumberInterface> {
 
     /**
      * The map of variables in this context.
@@ -47,10 +48,10 @@ open class EvaluationContext(val parent: EvaluationContext? = null,
             by ChainSearchDelegate { numberImplementation }
 
     /**
-     * The reducer inherited from this context's parent.
+     * The Abacus instance inherited from this context's parent.
      */
-    val inheritedReducer: Reducer<NumberInterface>
+    val inheritedAbacus: Abacus
-            by ChainSearchDelegate { reducer }
+            by ChainSearchDelegate { abacus }
 
     /**
      * The set of all variables in this context and its parents.

core/src/main/kotlin/org/nwapw/abacus/context/MutableEvaluationContext.kt

@@ -1,9 +1,11 @@
 package org.nwapw.abacus.context
 
+import org.nwapw.abacus.Abacus
+import org.nwapw.abacus.exception.NumberReducerException
+import org.nwapw.abacus.exception.ReductionException
 import org.nwapw.abacus.number.NumberInterface
 import org.nwapw.abacus.plugin.NumberImplementation
-import org.nwapw.abacus.tree.Reducer
+import org.nwapw.abacus.tree.nodes.*
-import org.nwapw.abacus.tree.TreeNode
 
 /**
  * A reduction context that is mutable.
@@ -13,11 +15,11 @@ import org.nwapw.abacus.tree.TreeNode
  */
 class MutableEvaluationContext(parent: EvaluationContext? = null,
                                numberImplementation: NumberImplementation? = null,
-                               reducer: Reducer<NumberInterface>? = null) :
+                               abacus: Abacus? = null) :
-        EvaluationContext(parent, numberImplementation, reducer) {
+        EvaluationContext(parent, numberImplementation, abacus) {
 
     override var numberImplementation: NumberImplementation? = super.numberImplementation
-    override var reducer: Reducer<NumberInterface>? = super.reducer
+    override var abacus: Abacus? = super.abacus
 
     /**
      * Writes data stored in the [other] context over data stored in this one.
@@ -25,7 +27,6 @@ class MutableEvaluationContext(parent: EvaluationContext? = null,
      */
     fun apply(other: EvaluationContext) {
         if(other.numberImplementation != null) numberImplementation = other.numberImplementation
-        if(other.reducer != null) reducer = other.reducer
         for(name in other.variables) {
             setVariable(name, other.getVariable(name) ?: continue)
         }
@@ -66,4 +67,53 @@ class MutableEvaluationContext(parent: EvaluationContext? = null,
         definitionMap.clear()
     }
 
+    override fun reduceNode(treeNode: TreeNode, vararg children: Any): NumberInterface {
+        val abacus = inheritedAbacus
+        val promotionManager = abacus.promotionManager
+        return when(treeNode){
+            is NumberNode -> {
+                inheritedNumberImplementation.instanceForString(treeNode.number)
+            }
+            is VariableNode -> {
+                val variable = getVariable(treeNode.variable)
+                if(variable != null) return variable
+                val definition = getDefinition(treeNode.variable)
+                if(definition != null) return definition.reduce(this)
+                throw NumberReducerException("variable is not defined.")
+            }
+            is NumberUnaryNode -> {
+                val child = children[0] as NumberInterface
+                numberImplementation = abacus.pluginManager.interfaceImplementationFor(child.javaClass)
+                abacus.pluginManager.operatorFor(treeNode.operation)
+                        .apply(this, child)
+            }
+            is NumberBinaryNode -> {
+                val left = children[0] as NumberInterface
+                val right = children[1] as NumberInterface
+                val promotionResult = promotionManager.promote(left, right)
+                numberImplementation = promotionResult.promotedTo
+                abacus.pluginManager.operatorFor(treeNode.operation).apply(this, *promotionResult.items)
+            }
+            is NumberFunctionNode -> {
+                val promotionResult = promotionManager
+                        .promote(*children.map { it as NumberInterface }.toTypedArray())
+                numberImplementation = promotionResult.promotedTo
+                abacus.pluginManager.functionFor(treeNode.callTo).apply(this, *promotionResult.items)
+            }
+            is TreeValueUnaryNode -> {
+                abacus.pluginManager.treeValueOperatorFor(treeNode.operation)
+                        .apply(this, treeNode.applyTo)
+            }
+            is TreeValueBinaryNode -> {
+                abacus.pluginManager.treeValueOperatorFor(treeNode.operation)
+                        .apply(this, treeNode.left, treeNode.right)
+            }
+            is TreeValueFunctionNode -> {
+                abacus.pluginManager.treeValueFunctionFor(treeNode.callTo)
+                        .apply(this, *treeNode.children.toTypedArray())
+            }
+            else -> throw ReductionException("unrecognized tree node.")
+        }
+    }
+
 }

core/src/main/kotlin/org/nwapw/abacus/function/Applicable.kt

@@ -1,4 +1,4 @@
-package org.nwapw.abacus.function.applicable
+package org.nwapw.abacus.function
 
 import org.nwapw.abacus.context.MutableEvaluationContext
 import org.nwapw.abacus.exception.DomainException

core/src/main/kotlin/org/nwapw/abacus/function/interfaces/NumberFunction.kt

@@ -1,6 +1,6 @@
-package org.nwapw.abacus.function
+package org.nwapw.abacus.function.interfaces
 
-import org.nwapw.abacus.function.applicable.Applicable
+import org.nwapw.abacus.function.Applicable
 import org.nwapw.abacus.number.NumberInterface
 
 /**

core/src/main/kotlin/org/nwapw/abacus/function/interfaces/NumberOperator.kt

@@ -1,6 +1,9 @@
-package org.nwapw.abacus.function
+package org.nwapw.abacus.function.interfaces
 
-import org.nwapw.abacus.function.applicable.Applicable
+import org.nwapw.abacus.function.Applicable
+import org.nwapw.abacus.function.Operator
+import org.nwapw.abacus.function.OperatorAssociativity
+import org.nwapw.abacus.function.OperatorType
 import org.nwapw.abacus.number.NumberInterface
 
 /**

core/src/main/kotlin/org/nwapw/abacus/function/interfaces/TreeValueFunction.kt

@@ -1,8 +1,8 @@
-package org.nwapw.abacus.function
+package org.nwapw.abacus.function.interfaces
 
-import org.nwapw.abacus.function.applicable.Applicable
+import org.nwapw.abacus.function.Applicable
 import org.nwapw.abacus.number.NumberInterface
-import org.nwapw.abacus.tree.TreeNode
+import org.nwapw.abacus.tree.nodes.TreeNode
 
 /**
  * A function that operates on trees.

core/src/main/kotlin/org/nwapw/abacus/function/interfaces/TreeValueOperator.kt

@@ -1,8 +1,11 @@
-package org.nwapw.abacus.function
+package org.nwapw.abacus.function.interfaces
 
-import org.nwapw.abacus.function.applicable.Applicable
+import org.nwapw.abacus.function.Applicable
+import org.nwapw.abacus.function.Operator
+import org.nwapw.abacus.function.OperatorAssociativity
+import org.nwapw.abacus.function.OperatorType
 import org.nwapw.abacus.number.NumberInterface
-import org.nwapw.abacus.tree.TreeNode
+import org.nwapw.abacus.tree.nodes.TreeNode
 
 /**
  * An operator that operates on trees.

core/src/main/kotlin/org/nwapw/abacus/number/NumberInterface.kt

@@ -1,253 +1,276 @@
-package org.nwapw.abacus.number;
+package org.nwapw.abacus.number
-
+
-import org.nwapw.abacus.exception.ComputationInterruptedException;
+import org.nwapw.abacus.exception.ComputationInterruptedException
-
+import org.nwapw.abacus.number.range.NumberRangeBuilder
-/**
+
- * An interface used to represent a number.
+abstract class NumberInterface: Comparable<NumberInterface> {
- */
+
-public abstract class NumberInterface implements Comparable<NumberInterface> {
+    /**
-
+     * Check if the thread was interrupted and
-    /**
+     * throw an exception to end the computation.
-     * Check if the thread was interrupted and
+     */
-     * throw an exception to end the computation.
+    private fun checkInterrupted(){
-     */
+        if(Thread.currentThread().isInterrupted)
-    private static void checkInterrupted() {
+            throw ComputationInterruptedException()
-        if (Thread.currentThread().isInterrupted())
+    }
-            throw new ComputationInterruptedException();
+
-    }
+    /**
-
+     * Returns the integer representation of this number, discarding any fractional part,
-    /**
+     * if int can hold the value.
-     * The maximum precision to which this number operates.
+     *
-     *
+     * @return the integer value of this number.
-     * @return the precision.
+     */
-     */
+    abstract fun intValue(): Int
-    public abstract int getMaxPrecision();
+    /**
-
+     * Same as Math.signum().
-    /**
+     *
-     * Multiplies this number by another, returning
+     * @return 1 if this number is positive, -1 if this number is negative, 0 if this number is 0.
-     * a new number instance.
+     */
-     *
+    abstract fun signum(): Int
-     * @param multiplier the multiplier
+
-     * @return the result of the multiplication.
+    /**
-     */
+     * The maximum precision to which this number operates.
-    protected abstract NumberInterface multiplyInternal(NumberInterface multiplier);
+     */
-
+    abstract val maxPrecision: Int
-    /**
+    /**
-     * Multiplies this number by another, returning
+     * Returns the smallest error this instance can tolerate depending
-     * a new number instance. Also, checks if the
+     * on its precision and value.
-     * thread has been interrupted, and if so, throws
+     */
-     * an exception.
+    abstract val maxError: NumberInterface
-     *
+
-     * @param multiplier the multiplier
+    /**
-     * @return the result of the multiplication.
+     * Adds this number to another, returning
-     */
+     * a new number instance.
-    public final NumberInterface multiply(NumberInterface multiplier) {
+     *
-        checkInterrupted();
+     * @param summand the summand
-        return multiplyInternal(multiplier);
+     * @return the result of the summation.
-    }
+     */
-
+    abstract fun addInternal(summand: NumberInterface): NumberInterface
-    /**
+    /**
-     * Divides this number by another, returning
+     * Subtracts another number from this number,
-     * a new number instance.
+     * a new number instance.
-     *
+     *
-     * @param divisor the divisor
+     * @param subtrahend the subtrahend.
-     * @return the result of the division.
+     * @return the result of the subtraction.
-     */
+     */
-    protected abstract NumberInterface divideInternal(NumberInterface divisor);
+    abstract fun subtractInternal(subtrahend: NumberInterface): NumberInterface
-
+    /**
-    /**
+     * Multiplies this number by another, returning
-     * Divides this number by another, returning
+     * a new number instance.
-     * a new number instance. Also, checks if the
+     *
-     * thread has been interrupted, and if so, throws
+     * @param multiplier the multiplier
-     * an exception.
+     * @return the result of the multiplication.
-     *
+     */
-     * @param divisor the divisor
+    abstract fun multiplyInternal(multiplier: NumberInterface): NumberInterface
-     * @return the result of the division.
+    /**
-     */
+     * Divides this number by another, returning
-    public final NumberInterface divide(NumberInterface divisor) {
+     * a new number instance.
-        checkInterrupted();
+     *
-        return divideInternal(divisor);
+     * @param divisor the divisor
-    }
+     * @return the result of the division.
-
+     */
-    /**
+    abstract fun divideInternal(divisor: NumberInterface): NumberInterface
-     * Adds this number to another, returning
+    /**
-     * a new number instance.
+     * Returns a new instance of this number with
-     *
+     * the sign flipped.
-     * @param summand the summand
+     *
-     * @return the result of the summation.
+     * @return the new instance.
-     */
+     */
-    protected abstract NumberInterface addInternal(NumberInterface summand);
+    abstract fun negateInternal(): NumberInterface
-
+    /**
-    /**
+     * Raises this number to an integer power.
-     * Adds this number to another, returning
+     *
-     * a new number instance. Also, checks if the
+     * @param exponent the exponent to which to take the number.
-     * thread has been interrupted, and if so, throws
+     * @return the resulting value.
-     * an exception.
+     */
-     *
+    abstract fun intPowInternal(pow: Int): NumberInterface
-     * @param summand the summand
+    /**
-     * @return the result of the summation.
+     * Returns the least integer greater than or equal to the number.
-     */
+     *
-    public final NumberInterface add(NumberInterface summand) {
+     * @return the least integer greater or equal to the number, if int can hold the value.
-        checkInterrupted();
+     */
-        return addInternal(summand);
+    abstract fun ceilingInternal(): NumberInterface
-    }
+    /**
-
+     * Return the greatest integer less than or equal to the number.
-    /**
+     *
-     * Subtracts another number from this number,
+     * @return the greatest integer smaller or equal the number.
-     * a new number instance.
+     */
-     *
+    abstract fun floorInternal(): NumberInterface
-     * @param subtrahend the subtrahend.
+    /**
-     * @return the result of the subtraction.
+     * Returns the fractional part of the number.
-     */
+     *
-    protected abstract NumberInterface subtractInternal(NumberInterface subtrahend);
+     * @return the fractional part of the number.
-
+     */
-    /**
+    abstract fun fractionalPartInternal(): NumberInterface
-     * Subtracts another number from this number,
+
-     * a new number instance. Also, checks if the
+    /**
-     * thread has been interrupted, and if so, throws
+     * Adds this number to another, returning
-     * an exception.
+     * a new number instance. Also, checks if the
-     *
+     * thread has been interrupted, and if so, throws
-     * @param subtrahend the subtrahend.
+     * an exception.
-     * @return the result of the subtraction.
+     *
-     */
+     * @param summand the summand
-    public final NumberInterface subtract(NumberInterface subtrahend) {
+     * @return the result of the summation.
-        checkInterrupted();
+     */
-        return subtractInternal(subtrahend);
+    fun add(summand: NumberInterface): NumberInterface {
-    }
+        checkInterrupted()
-
+        return addInternal(summand)
-    /**
+    }
-     * Returns a new instance of this number with
+
-     * the sign flipped.
+    /**
-     *
+     * Subtracts another number from this number,
-     * @return the new instance.
+     * a new number instance. Also, checks if the
-     */
+     * thread has been interrupted, and if so, throws
-    protected abstract NumberInterface negateInternal();
+     * an exception.
-
+     *
-
+     * @param subtrahend the subtrahend.
-    /**
+     * @return the result of the subtraction.
-     * Returns a new instance of this number with
+     */
-     * the sign flipped. Also, checks if the
+    fun subtract(subtrahend: NumberInterface): NumberInterface {
-     * thread has been interrupted, and if so, throws
+        checkInterrupted()
-     * an exception.
+        return subtractInternal(subtrahend)
-     *
+    }
-     * @return the new instance.
+
-     */
+    /**
-    public final NumberInterface negate() {
+     * Multiplies this number by another, returning
-        checkInterrupted();
+     * a new number instance. Also, checks if the
-        return negateInternal();
+     * thread has been interrupted, and if so, throws
-    }
+     * an exception.
-
+     *
-    /**
+     * @param multiplier the multiplier
-     * Raises this number to an integer power.
+     * @return the result of the multiplication.
-     *
+     */
-     * @param exponent the exponent to which to take the number.
+    fun multiply(multiplier: NumberInterface): NumberInterface {
-     * @return the resulting value.
+        checkInterrupted()
-     */
+        return multiplyInternal(multiplier)
-    protected abstract NumberInterface intPowInternal(int exponent);
+    }
-
+
-    /**
+    /**
-     * Raises this number to an integer power. Also, checks if the
+     * Divides this number by another, returning
-     * thread has been interrupted, and if so, throws
+     * a new number instance. Also, checks if the
-     * an exception.
+     * thread has been interrupted, and if so, throws
-     *
+     * an exception.
-     * @param exponent the exponent to which to take the number.
+     *
-     * @return the resulting value.
+     * @param divisor the divisor
-     */
+     * @return the result of the division.
-    public final NumberInterface intPow(int exponent) {
+     */
-        checkInterrupted();
+    fun divide(divisor: NumberInterface): NumberInterface {
-        return intPowInternal(exponent);
+        checkInterrupted()
-    }
+        return divideInternal(divisor)
-
+    }
-    /**
+
-     * Same as Math.signum().
+    /**
-     *
+     * Returns a new instance of this number with
-     * @return 1 if this number is positive, -1 if this number is negative, 0 if this number is 0.
+     * the sign flipped. Also, checks if the
-     */
+     * thread has been interrupted, and if so, throws
-    public abstract int signum();
+     * an exception.
-
+     *
-    /**
+     * @return the new instance.
-     * Returns the least integer greater than or equal to the number.
+     */
-     *
+    fun negate(): NumberInterface {
-     * @return the least integer greater or equal to the number, if int can hold the value.
+        checkInterrupted()
-     */
+        return negateInternal()
-    protected abstract NumberInterface ceilingInternal();
+    }
-
+
-    /**
+    /**
-     * Returns the least integer greater than or equal to the number.
+     * Raises this number to an integer power. Also, checks if the
-     * Also, checks if the thread has been interrupted, and if so, throws
+     * thread has been interrupted, and if so, throws
-     * an exception.
+     * an exception.
-     *
+     *
-     * @return the least integer bigger or equal to the number.
+     * @param exponent the exponent to which to take the number.
-     */
+     * @return the resulting value.
-    public final NumberInterface ceiling() {
+     */
-        checkInterrupted();
+    fun intPow(exponent: Int): NumberInterface {
-        return ceilingInternal();
+        checkInterrupted()
-    }
+        return intPowInternal(exponent)
-
+    }
-    /**
+
-     * Return the greatest integer less than or equal to the number.
+    /**
-     *
+     * Returns the least integer greater than or equal to the number.
-     * @return the greatest integer smaller or equal the number.
+     * Also, checks if the thread has been interrupted, and if so, throws
-     */
+     * an exception.
-    protected abstract NumberInterface floorInternal();
+     *
-
+     * @return the least integer bigger or equal to the number.
-    /**
+     */
-     * Return the greatest integer less than or equal to the number.
+    fun ceiling(): NumberInterface {
-     * Also, checks if the thread has been interrupted, and if so, throws
+        checkInterrupted()
-     * an exception.
+        return ceilingInternal()
-     *
+    }
-     * @return the greatest int smaller than or equal to the number.
+
-     */
+    /**
-    public final NumberInterface floor() {
+     * Return the greatest integer less than or equal to the number.
-        checkInterrupted();
+     * Also, checks if the thread has been interrupted, and if so, throws
-        return floorInternal();
+     * an exception.
-    }
+     *
-
+     * @return the greatest int smaller than or equal to the number.
-    /**
+     */
-     * Returns the fractional part of the number.
+    fun floor(): NumberInterface {
-     *
+        checkInterrupted()
-     * @return the fractional part of the number.
+        return floorInternal()
-     */
+    }
-    protected abstract NumberInterface fractionalPartInternal();
+
-
+    /**
-    /**
+     * Returns the fractional part of the number, specifically x - floor(x).
-     * Returns the fractional part of the number, specifically x - floor(x).
+     * Also, checks if the thread has been interrupted,
-     * Also, checks if the thread has been interrupted,
+     * and if so, throws an exception.
-     * and if so, throws an exception.
+     *
-     *
+     * @return the fractional part of the number.
-     * @return the fractional part of the number.
+     */
-     */
+    fun fractionalPart(): NumberInterface {
-    public final NumberInterface fractionalPart() {
+        checkInterrupted()
-        checkInterrupted();
+        return fractionalPartInternal()
-        return fractionalPartInternal();
+    }
-    }
+
-
+    /**
-    /**
+     * Checks whether the given number is an integer or not.
-     * Returns the integer representation of this number, discarding any fractional part,
+     *
-     * if int can hold the value.
+     * @return whether the number is an integer or not.
-     *
+     */
-     * @return the integer value of this number.
+    fun isInteger() = fractionalPart().signum() == 0
-     */
+
-    public abstract int intValue();
+    /**
-
+     * Returns a NumberRangeBuilder object, which is used to create a range.
-    /**
+     * The reason that this returns a builder and not an actual range is that
-     * Returns the smallest error this instance can tolerate depending
+     * the NumberRange needs to promote values passed to it, which
-     * on its precision and value.
+     * requires an abacus instance.
-     *
+     * @param other the value at the bottom of the range.
-     * @return the smallest error that should be permitted in calculations.
+     * @return the resulting range builder.
-     */
+     */
-    public abstract NumberInterface getMaxError();
+    operator fun rangeTo(other: NumberInterface) = NumberRangeBuilder(this, other)
-
+
-    /**
+    /**
-     * Returns a NumberRangeBuilder object, which is used to create a range.
+     * Plus operator overloaded to allow "nice" looking math.
-     * The reason that this returns a builder and not an actual range is that
+     * @param other the value to add to this number.
-     * the NumberRange needs to promote values passed to it, which
+     * @return the result of the addition.
-     * requires an abacus instance.
+     */
-     * @param other the value at the bottom of the range.
+    operator fun plus(other: NumberInterface) = add(other)
-     * @return the resulting range builder.
+    /**
-     */
+     * Minus operator overloaded to allow "nice" looking math.
-    public NumberRangeBuilder rangeTo(NumberInterface other){
+     * @param other the value to subtract to this number.
-        return new NumberRangeBuilder(this, other);
+     * @return the result of the subtraction.
-    }
+     */
-
+    operator fun minus(other: NumberInterface) = subtract(other)
-}
+    /**
+     * Times operator overloaded to allow "nice" looking math.
+     * @param other the value to multiply this number by.
+     * @return the result of the multiplication.
+     */
+    operator fun times(other: NumberInterface) = multiply(other)
+    /**
+     * Divide operator overloaded to allow "nice" looking math.
+     * @param other the value to divide this number by.
+     * @return the result of the division.
+     */
+    operator fun div(other: NumberInterface) = divide(other)
+    /**
+     * The plus operator.
+     * @return this number.
+     */
+    operator fun unaryPlus() = this
+    /**
+     * The minus operator.
+     * @return the negative of this number.
+     */
+    operator fun unaryMinus() = negate()
+
+}

core/src/main/kotlin/org/nwapw/abacus/number/promotion/NumberUtils.kt

@@ -1,7 +1,8 @@
 @file:JvmName("NumberUtils")
-package org.nwapw.abacus.number
+package org.nwapw.abacus.number.promotion
+
+import org.nwapw.abacus.number.NumberInterface
 
-typealias PromotionFunction = java.util.function.Function<NumberInterface, NumberInterface>
 typealias PromotionPath = List<PromotionFunction>
 typealias NumberClass = Class<NumberInterface>
 
@@ -12,5 +13,5 @@ typealias NumberClass = Class<NumberInterface>
  * @param from the number to start from.
  */
 fun PromotionPath.promote(from: NumberInterface): NumberInterface {
-    return fold(from, { current, function -> function.apply(current) })
+    return fold(from, { current, function -> function.promote(current) })
 }

core/src/main/kotlin/org/nwapw/abacus/number/promotion/PromotionFunction.kt

@@ -0,0 +1,20 @@
+package org.nwapw.abacus.number.promotion
+
+import org.nwapw.abacus.number.NumberInterface
+
+/**
+ * Function that is used to promote a number from one type to another.
+ *
+ * A promotion function is used in the promotion system as a mean to
+ * actually "travel" down the promotion path.
+ */
+interface PromotionFunction {
+
+    /**
+     * Promotes the given [number] into another type.
+     * @param number the number to promote from.
+     * @return the new number with the same value.
+     */
+    fun promote(number: NumberInterface): NumberInterface
+
+}

core/src/main/kotlin/org/nwapw/abacus/number/promotion/PromotionManager.kt

@@ -1,11 +1,11 @@
-package org.nwapw.abacus.number
+package org.nwapw.abacus.number.promotion
 
 import org.nwapw.abacus.Abacus
 import org.nwapw.abacus.exception.PromotionException
+import org.nwapw.abacus.number.NumberInterface
 import org.nwapw.abacus.plugin.NumberImplementation
 import org.nwapw.abacus.plugin.PluginListener
 import org.nwapw.abacus.plugin.PluginManager
-import java.util.function.Function
 
 /**
  * A class that handles promotions based on priority and the
@@ -31,7 +31,11 @@ class PromotionManager(val abacus: Abacus) : PluginListener {
         val fromName = abacus.pluginManager.interfaceImplementationNameFor(from.implementation)
         val toName = abacus.pluginManager.interfaceImplementationNameFor(to.implementation)
 
-        if(fromName == toName) return listOf(Function { it })
+        if(fromName == toName) return listOf(object : PromotionFunction {
+            override fun promote(number: NumberInterface): NumberInterface {
+                return number
+            }
+        })
 
         if(from.promotionPaths.containsKey(toName))
             return listOf(from.promotionPaths[toName] ?: return null)
@@ -51,7 +55,7 @@ class PromotionManager(val abacus: Abacus) : PluginListener {
         val implementations = numbers.map { pluginManager.interfaceImplementationFor(it.javaClass) }
         val highestPriority = implementations.sortedBy { it.priority }.last()
         return PromotionResult(items = numbers.map {
-            if(it.javaClass == highestPriority.implementation) it
+            if (it.javaClass == highestPriority.implementation) it
             else computePaths[pluginManager.interfaceImplementationFor(it.javaClass) to highestPriority]
                     ?.promote(it) ?: throw PromotionException()
         }.toTypedArray(), promotedTo = highestPriority)

core/src/main/kotlin/org/nwapw/abacus/number/promotion/PromotionResult.kt

@@ -1,5 +1,6 @@
-package org.nwapw.abacus.number
+package org.nwapw.abacus.number.promotion
 
+import org.nwapw.abacus.number.NumberInterface
 import org.nwapw.abacus.plugin.NumberImplementation
 
 /**

core/src/main/kotlin/org/nwapw/abacus/number/range/NumberRange.kt

@@ -1,6 +1,7 @@
-package org.nwapw.abacus.number
+package org.nwapw.abacus.number.range
 
 import org.nwapw.abacus.Abacus
+import org.nwapw.abacus.number.NumberInterface
 
 /**
  * A closed range designed specifically for [NumberInterface]

core/src/main/kotlin/org/nwapw/abacus/number/range/NumberRangeBuilder.kt

@@ -1,6 +1,7 @@
-package org.nwapw.abacus.number
+package org.nwapw.abacus.number.range
 
 import org.nwapw.abacus.Abacus
+import org.nwapw.abacus.number.NumberInterface
 
 /**
  * A utility class for creating [NumberRange] instances.

core/src/main/kotlin/org/nwapw/abacus/parsing/Parser.kt

@@ -1,16 +1,17 @@
-package org.nwapw.abacus.parsing;
+package org.nwapw.abacus.parsing
 
-import org.nwapw.abacus.tree.TreeNode;
+import org.nwapw.abacus.tree.nodes.TreeNode
-
-import java.util.List;
 
 /**
- * An itnerface that provides the ability to convert a list of tokens
+ * Converter from tokens into a parse tree.
+ *
+ * An interface that provides the ability to convert a list of tokens
  * into a parse tree.
  *
  * @param <T> the type of tokens accepted by this parser.
  */
-public interface Parser<T> {
+
+interface Parser<in T> {
 
     /**
      * Constructs a tree out of the given tokens.
@@ -18,5 +19,6 @@ 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);
+    fun constructTree(tokens: List<T>): TreeNode
-}
+
+}

core/src/main/kotlin/org/nwapw/abacus/parsing/Tokenizer.kt

@@ -0,0 +1,21 @@
+package org.nwapw.abacus.parsing
+
+/**
+ * Converter from string to tokens.
+ *
+ * Interface that converts a string into a list
+ * of tokens of a certain type.
+ *
+ * @param <T> the type of the tokens produced.
+ */
+interface Tokenizer<out T> {
+
+    /**
+     * Converts a string into tokens.
+     *
+     * @param string the string to convert.
+     * @return the list of tokens, or null on error.
+     */
+    fun tokenizeString(string: String):  List<T>
+
+}

core/src/main/kotlin/org/nwapw/abacus/parsing/TreeBuilder.kt

@@ -0,0 +1,26 @@
+package org.nwapw.abacus.parsing
+
+import org.nwapw.abacus.tree.nodes.TreeNode
+
+/**
+ * Class to combine a [Tokenizer] and a [Parser]
+ *
+ * TreeBuilder class used to piece together a Tokenizer and
+ * Parser of the same kind. This is used to essentially avoid
+ * working with any parameters at all, and the generics
+ * in this class are used only to ensure the tokenizer and parser
+ * are of the same type.
+ *
+ * @param <T> the type of tokens created by the tokenizer and used by the parser.
+ */
+class TreeBuilder<T>(private val tokenizer: Tokenizer<T>, private val parser: Parser<T>) {
+
+    /**
+     * Parses the given [string] into a tree.
+     *
+     * @param string the string to parse into a tree.
+     * @return the resulting tree.
+     */
+    fun fromString(string: String): TreeNode = parser.constructTree(tokenizer.tokenizeString(string))
+
+}

core/src/main/kotlin/org/nwapw/abacus/plugin/standard/operator/OperatorAdd.kt

@@ -0,0 +1,21 @@
+package org.nwapw.abacus.plugin.standard.operator
+
+import org.nwapw.abacus.context.MutableEvaluationContext
+import org.nwapw.abacus.function.OperatorAssociativity
+import org.nwapw.abacus.function.OperatorType
+import org.nwapw.abacus.function.interfaces.NumberOperator
+import org.nwapw.abacus.number.NumberInterface
+
+/**
+ * The addition operator.
+ *
+ * This is a standard operator that simply performs addition.
+ */
+class OperatorAdd: NumberOperator(OperatorAssociativity.LEFT, OperatorType.BINARY_INFIX, 0) {
+
+    override fun matchesParams(context: MutableEvaluationContext, params: Array<out NumberInterface>) =
+            params.size == 2
+    override fun applyInternal(context: MutableEvaluationContext, params: Array<out NumberInterface>) =
+            params[0] + params[1]
+
+}

core/src/main/kotlin/org/nwapw/abacus/plugin/standard/operator/OperatorCaret.kt

@@ -0,0 +1,38 @@
+package org.nwapw.abacus.plugin.standard.operator
+
+import org.nwapw.abacus.context.MutableEvaluationContext
+import org.nwapw.abacus.function.OperatorAssociativity
+import org.nwapw.abacus.function.OperatorType
+import org.nwapw.abacus.function.interfaces.NumberOperator
+import org.nwapw.abacus.number.NumberInterface
+import org.nwapw.abacus.plugin.standard.StandardPlugin.*
+
+/**
+ * The power operator.
+ *
+ * This is a standard operator that brings one number to the power of the other.
+ */
+class OperatorCaret: NumberOperator(OperatorAssociativity.RIGHT, OperatorType.BINARY_INFIX, 2) {
+
+    override fun matchesParams(context: MutableEvaluationContext, params: Array<out NumberInterface>) =
+            params.size == 2
+                    && !(params[0].signum() == 0 && params[1].signum() == 0)
+                    && !(params[0].signum() == -1 && !params[1].isInteger())
+
+    override fun applyInternal(context: MutableEvaluationContext, params: Array<out NumberInterface>): NumberInterface {
+        val implementation = context.inheritedNumberImplementation
+        if (params[0].signum() == 0)
+            return implementation.instanceForString("0")
+        else if (params[1].signum() == 0)
+            return implementation.instanceForString("1")
+        //Detect integer bases:
+        if (params[0].isInteger()
+                && FUNCTION_ABS.apply(context, params[1]) < implementation.instanceForString(Integer.toString(Integer.MAX_VALUE))
+                && FUNCTION_ABS.apply(context, params[1]) >= implementation.instanceForString("1")) {
+            val newParams = arrayOf(params[0], params[1].fractionalPart())
+            return params[0].intPow(params[1].floor().intValue()) * applyInternal(context, newParams)
+        }
+        return FUNCTION_EXP.apply(context, FUNCTION_LN.apply(context, FUNCTION_ABS.apply(context, params[0])) * params[1])
+    }
+
+}

core/src/main/kotlin/org/nwapw/abacus/plugin/standard/operator/OperatorDefine.kt

@@ -0,0 +1,28 @@
+package org.nwapw.abacus.plugin.standard.operator
+
+import org.nwapw.abacus.context.MutableEvaluationContext
+import org.nwapw.abacus.function.OperatorAssociativity
+import org.nwapw.abacus.function.OperatorType
+import org.nwapw.abacus.function.interfaces.TreeValueOperator
+import org.nwapw.abacus.number.NumberInterface
+import org.nwapw.abacus.tree.nodes.TreeNode
+import org.nwapw.abacus.tree.nodes.VariableNode
+
+/**
+ * The definition operator.
+ *
+ * This is a standard operator that creates a definition - something that doesn't capture variable values
+ * when it's created, but rather the variables themselves, and changes when the variables it uses change.
+ */
+class OperatorDefine: TreeValueOperator(OperatorAssociativity.LEFT, OperatorType.BINARY_INFIX, 0) {
+
+    override fun matchesParams(context: MutableEvaluationContext, params: Array<out TreeNode>) =
+            params.size == 2 && params[0] is VariableNode
+
+    override fun applyInternal(context: MutableEvaluationContext, params: Array<out TreeNode>): NumberInterface {
+        val assignTo = (params[0] as VariableNode).variable
+        context.setDefinition(assignTo, params[1])
+        return params[1].reduce(context)
+    }
+
+}

core/src/main/kotlin/org/nwapw/abacus/plugin/standard/operator/OperatorDivide.kt

@@ -0,0 +1,21 @@
+package org.nwapw.abacus.plugin.standard.operator
+
+import org.nwapw.abacus.context.MutableEvaluationContext
+import org.nwapw.abacus.function.OperatorAssociativity
+import org.nwapw.abacus.function.OperatorType
+import org.nwapw.abacus.function.interfaces.NumberOperator
+import org.nwapw.abacus.number.NumberInterface
+
+/**
+ * The division operator.
+ *
+ * This is a standard operator that simply performs division.
+ */
+class OperatorDivide: NumberOperator(OperatorAssociativity.LEFT, OperatorType.BINARY_INFIX, 1) {
+
+    override fun matchesParams(context: MutableEvaluationContext, params: Array<out NumberInterface>) =
+            params.size == 2
+    override fun applyInternal(context: MutableEvaluationContext, params: Array<out NumberInterface>) =
+            params[0] / params[1]
+
+}

core/src/main/kotlin/org/nwapw/abacus/plugin/standard/operator/OperatorFactorial.kt

@@ -0,0 +1,37 @@
+package org.nwapw.abacus.plugin.standard.operator
+
+import org.nwapw.abacus.context.MutableEvaluationContext
+import org.nwapw.abacus.function.OperatorAssociativity
+import org.nwapw.abacus.function.OperatorType
+import org.nwapw.abacus.function.interfaces.NumberOperator
+import org.nwapw.abacus.number.NumberInterface
+
+/**
+ * The factorial operator.
+ *
+ * This is a standard operator that simply evaluates the factorial of a number.
+ */
+class OperatorFactorial: NumberOperator(OperatorAssociativity.LEFT, OperatorType.UNARY_POSTFIX, 0) {
+
+    override fun matchesParams(context: MutableEvaluationContext, params: Array<out NumberInterface>) =
+        params.size == 1
+                && params[0].isInteger()
+                && params[0].signum() >= 0
+
+    override fun applyInternal(context: MutableEvaluationContext, params: Array<out NumberInterface>): NumberInterface {
+        val implementation = context.inheritedNumberImplementation
+        val one = implementation.instanceForString("1")
+        if (params[0].signum() == 0) {
+            return one
+        }
+        var factorial = params[0]
+        var multiplier = params[0] - one
+        //It is necessary to later prevent calls of factorial on anything but non-negative integers.
+        while (multiplier.signum() == 1) {
+            factorial *= multiplier
+            multiplier -= one
+        }
+        return factorial
+    }
+
+}

core/src/main/kotlin/org/nwapw/abacus/plugin/standard/operator/OperatorMultiply.kt

@@ -0,0 +1,21 @@
+package org.nwapw.abacus.plugin.standard.operator
+
+import org.nwapw.abacus.context.MutableEvaluationContext
+import org.nwapw.abacus.function.OperatorAssociativity
+import org.nwapw.abacus.function.OperatorType
+import org.nwapw.abacus.function.interfaces.NumberOperator
+import org.nwapw.abacus.number.NumberInterface
+
+/**
+ * The multiplication operator.
+ *
+ * This is a standard operator that simply performs multiplication.
+ */
+class OperatorMultiply: NumberOperator(OperatorAssociativity.LEFT, OperatorType.BINARY_INFIX, 1) {
+
+    override fun matchesParams(context: MutableEvaluationContext, params: Array<out NumberInterface>) =
+            params.size == 2
+    override fun applyInternal(context: MutableEvaluationContext, params: Array<out NumberInterface>) =
+            params[0] * params[1]
+
+}

core/src/main/kotlin/org/nwapw/abacus/plugin/standard/operator/OperatorNcr.kt

@@ -0,0 +1,26 @@
+package org.nwapw.abacus.plugin.standard.operator
+
+import org.nwapw.abacus.context.MutableEvaluationContext
+import org.nwapw.abacus.function.OperatorAssociativity
+import org.nwapw.abacus.function.OperatorType
+import org.nwapw.abacus.function.interfaces.NumberOperator
+import org.nwapw.abacus.number.NumberInterface
+import org.nwapw.abacus.plugin.standard.StandardPlugin.OP_FACTORIAL
+import org.nwapw.abacus.plugin.standard.StandardPlugin.OP_NPR
+
+/**
+ * The "N choose R" operator.
+ *
+ * This is a standard operator that returns the number of possible combinations, regardless of order,
+ * of a certain size can be taken out of a pool of a bigger size.
+ */
+class OperatorNcr: NumberOperator(OperatorAssociativity.RIGHT, OperatorType.BINARY_INFIX, 0) {
+
+    override fun matchesParams(context: MutableEvaluationContext, params: Array<out NumberInterface>) =
+            params.size == 2 && params[0].isInteger()
+                    && params[1].isInteger()
+
+    override fun applyInternal(context: MutableEvaluationContext, params: Array<out NumberInterface>) =
+            OP_NPR.apply(context, *params) / OP_FACTORIAL.apply(context, params[1])
+
+}

core/src/main/kotlin/org/nwapw/abacus/plugin/standard/operator/OperatorNegate.kt

@@ -0,0 +1,22 @@
+package org.nwapw.abacus.plugin.standard.operator
+
+import org.nwapw.abacus.context.MutableEvaluationContext
+import org.nwapw.abacus.function.OperatorAssociativity
+import org.nwapw.abacus.function.OperatorType
+import org.nwapw.abacus.function.interfaces.NumberOperator
+import org.nwapw.abacus.number.NumberInterface
+
+/**
+ * The negation operator.
+ *
+ * This is a standard operator that negates a number.
+ */
+class OperatorNegate: NumberOperator(OperatorAssociativity.LEFT, OperatorType.UNARY_PREFIX, 0) {
+
+    override fun matchesParams(context: MutableEvaluationContext, params: Array<out NumberInterface>) =
+            params.size == 1
+
+    override fun applyInternal(context: MutableEvaluationContext, params: Array<out NumberInterface>) =
+            -params[0]
+
+}

core/src/main/kotlin/org/nwapw/abacus/plugin/standard/operator/OperatorNpr.kt

@@ -0,0 +1,42 @@
+package org.nwapw.abacus.plugin.standard.operator
+
+import org.nwapw.abacus.context.MutableEvaluationContext
+import org.nwapw.abacus.function.OperatorAssociativity
+import org.nwapw.abacus.function.OperatorType
+import org.nwapw.abacus.function.interfaces.NumberOperator
+import org.nwapw.abacus.number.NumberInterface
+
+/**
+ * The "N pick R" operator.
+ *
+ * his is a standard operator that returns the number of possible combinations
+ * of a certain size can be taken out of a pool of a bigger size.
+ */
+class OperatorNpr: NumberOperator(OperatorAssociativity.RIGHT, OperatorType.BINARY_INFIX, 0) {
+
+    override fun matchesParams(context: MutableEvaluationContext, params: Array<out NumberInterface>) =
+            params.size == 2 && params[0].isInteger()
+                    && params[1].isInteger()
+
+    override fun applyInternal(context: MutableEvaluationContext, params: Array<out NumberInterface>): NumberInterface {
+        val implementation = context.inheritedNumberImplementation
+        if (params[0] < params[1] ||
+                params[0].signum() < 0 ||
+                params[0].signum() == 0 && params[1].signum() != 0)
+            return implementation.instanceForString("0")
+        var total = implementation.instanceForString("1")
+        var multiplyBy = params[0]
+        var remainingMultiplications = params[1]
+        val halfway = params[0] / implementation.instanceForString("2")
+        if (remainingMultiplications > halfway) {
+            remainingMultiplications = params[0] - remainingMultiplications
+        }
+        while (remainingMultiplications.signum() > 0) {
+            total *= multiplyBy
+            remainingMultiplications -= implementation.instanceForString("1")
+            multiplyBy -= implementation.instanceForString("1")
+        }
+        return total
+    }
+
+}

core/src/main/kotlin/org/nwapw/abacus/plugin/standard/operator/OperatorSet.kt

@@ -0,0 +1,28 @@
+package org.nwapw.abacus.plugin.standard.operator
+
+import org.nwapw.abacus.context.MutableEvaluationContext
+import org.nwapw.abacus.function.OperatorAssociativity
+import org.nwapw.abacus.function.OperatorType
+import org.nwapw.abacus.function.interfaces.TreeValueOperator
+import org.nwapw.abacus.number.NumberInterface
+import org.nwapw.abacus.tree.nodes.TreeNode
+import org.nwapw.abacus.tree.nodes.VariableNode
+
+/**
+ * The set operator.
+ *
+ * This is a standard operator that assigns a value to a variable name.
+ */
+class OperatorSet: TreeValueOperator(OperatorAssociativity.LEFT, OperatorType.BINARY_INFIX, 0) {
+
+    override fun matchesParams(context: MutableEvaluationContext, params: Array<out TreeNode>) =
+            params.size == 2 && params[0] is VariableNode
+
+    override fun applyInternal(context: MutableEvaluationContext, params: Array<out TreeNode>): NumberInterface {
+        val assignTo = (params[0] as VariableNode).variable
+        val value = params[1].reduce(context)
+        context.setVariable(assignTo, value)
+        return value
+    }
+
+}

core/src/main/kotlin/org/nwapw/abacus/plugin/standard/operator/OperatorSubtract.kt

@@ -0,0 +1,21 @@
+package org.nwapw.abacus.plugin.standard.operator
+
+import org.nwapw.abacus.context.MutableEvaluationContext
+import org.nwapw.abacus.function.OperatorAssociativity
+import org.nwapw.abacus.function.OperatorType
+import org.nwapw.abacus.function.interfaces.NumberOperator
+import org.nwapw.abacus.number.NumberInterface
+
+/**
+ * The subtraction operator.
+ *
+ * This is a standard operator that performs subtraction.
+ */
+class OperatorSubtract: NumberOperator(OperatorAssociativity.LEFT, OperatorType.BINARY_INFIX, 0) {
+
+    override fun matchesParams(context: MutableEvaluationContext, params: Array<out NumberInterface>) =
+            params.size == 2
+    override fun applyInternal(context: MutableEvaluationContext, params: Array<out NumberInterface>) =
+            params[0] - params[1]
+
+}

core/src/main/kotlin/org/nwapw/abacus/tree/NumberReducer.kt

@@ -1,65 +0,0 @@
-package org.nwapw.abacus.tree
-
-import org.nwapw.abacus.Abacus
-import org.nwapw.abacus.context.EvaluationContext
-import org.nwapw.abacus.exception.NumberReducerException
-import org.nwapw.abacus.exception.ReductionException
-import org.nwapw.abacus.number.NumberInterface
-
-class NumberReducer(val abacus: Abacus, context: EvaluationContext) : Reducer<NumberInterface> {
-
-    val context = context.mutableSubInstance()
-
-    init {
-        this.context.reducer = this
-    }
-
-    override fun reduceNode(treeNode: TreeNode, vararg children: Any): NumberInterface {
-        val promotionManager = abacus.promotionManager
-        return when(treeNode){
-            is NumberNode -> {
-                context.inheritedNumberImplementation.instanceForString(treeNode.number)
-            }
-            is VariableNode -> {
-                val variable = context.getVariable(treeNode.variable)
-                if(variable != null) return variable
-                val definition = context.getDefinition(treeNode.variable)
-                if(definition != null) return definition.reduce(this)
-                throw NumberReducerException("variable is not defined.")
-            }
-            is NumberUnaryNode -> {
-                val child = children[0] as NumberInterface
-                context.numberImplementation = abacus.pluginManager.interfaceImplementationFor(child.javaClass)
-                abacus.pluginManager.operatorFor(treeNode.operation)
-                        .apply(context, child)
-            }
-            is NumberBinaryNode -> {
-                val left = children[0] as NumberInterface
-                val right = children[1] as NumberInterface
-                val promotionResult = promotionManager.promote(left, right)
-                context.numberImplementation = promotionResult.promotedTo
-                abacus.pluginManager.operatorFor(treeNode.operation).apply(context, *promotionResult.items)
-            }
-            is FunctionNode -> {
-                val promotionResult = promotionManager
-                        .promote(*children.map { it as NumberInterface }.toTypedArray())
-                context.numberImplementation = promotionResult.promotedTo
-                abacus.pluginManager.functionFor(treeNode.callTo).apply(context, *promotionResult.items)
-            }
-            is TreeValueUnaryNode -> {
-                abacus.pluginManager.treeValueOperatorFor(treeNode.operation)
-                        .apply(context, treeNode.applyTo)
-            }
-            is TreeValueBinaryNode -> {
-                abacus.pluginManager.treeValueOperatorFor(treeNode.operation)
-                        .apply(context, treeNode.left, treeNode.right)
-            }
-            is TreeValueFunctionNode -> {
-                abacus.pluginManager.treeValueFunctionFor(treeNode.callTo)
-                        .apply(context, *treeNode.children.toTypedArray())
-            }
-            else -> throw ReductionException("unrecognized tree node.")
-        }
-    }
-
-}

core/src/main/kotlin/org/nwapw/abacus/tree/Reducer.kt

@@ -1,5 +1,7 @@
 package org.nwapw.abacus.tree
 
+import org.nwapw.abacus.tree.nodes.TreeNode
+
 /**
  * Reducer interface that takes a tree and returns a single value.
  *

core/src/main/kotlin/org/nwapw/abacus/tree/nodes/BinaryNode.kt

@@ -1,4 +1,4 @@
-package org.nwapw.abacus.tree
+package org.nwapw.abacus.tree.nodes
 
 /**
  * A tree node that holds a binary operation.

core/src/main/kotlin/org/nwapw/abacus/tree/nodes/CallNode.kt

@@ -1,4 +1,4 @@
-package org.nwapw.abacus.tree
+package org.nwapw.abacus.tree.nodes
 
 /**
  * Represents a more generic function call.

core/src/main/kotlin/org/nwapw/abacus/tree/nodes/NumberBinaryNode.kt

@@ -1,4 +1,6 @@
-package org.nwapw.abacus.tree
+package org.nwapw.abacus.tree.nodes
+
+import org.nwapw.abacus.tree.Reducer
 
 /**
  * A binary operator node that reduces its children.

core/src/main/kotlin/org/nwapw/abacus/tree/nodes/NumberFunctionNode.kt

@@ -1,4 +1,6 @@
-package org.nwapw.abacus.tree
+package org.nwapw.abacus.tree.nodes
+
+import org.nwapw.abacus.tree.Reducer
 
 /**
  * A tree node that holds a function call.
@@ -8,7 +10,7 @@ package org.nwapw.abacus.tree
  *
  * @param function the function string.
  */
-class FunctionNode(function: String, children: List<TreeNode>) : CallNode(function, children) {
+class NumberFunctionNode(function: String, children: List<TreeNode>) : CallNode(function, children) {
 
     override fun <T : Any> reduce(reducer: Reducer<T>): T {
         val children = Array<Any>(children.size, { children[it].reduce(reducer) })

core/src/main/kotlin/org/nwapw/abacus/tree/nodes/NumberNode.kt

@@ -1,4 +1,6 @@
-package org.nwapw.abacus.tree
+package org.nwapw.abacus.tree.nodes
+
+import org.nwapw.abacus.tree.Reducer
 
 /**
  * A tree node that holds a single number value.

core/src/main/kotlin/org/nwapw/abacus/tree/nodes/NumberUnaryNode.kt

@@ -1,4 +1,6 @@
-package org.nwapw.abacus.tree
+package org.nwapw.abacus.tree.nodes
+
+import org.nwapw.abacus.tree.Reducer
 
 /**
  * A unary operator node that reduces its children.

core/src/main/kotlin/org/nwapw/abacus/tree/nodes/TreeNode.kt

@@ -1,4 +1,6 @@
-package org.nwapw.abacus.tree
+package org.nwapw.abacus.tree.nodes
+
+import org.nwapw.abacus.tree.Reducer
 
 /**
  * A tree node.

core/src/main/kotlin/org/nwapw/abacus/tree/nodes/TreeValueBinaryNode.kt

@@ -1,4 +1,6 @@
-package org.nwapw.abacus.tree
+package org.nwapw.abacus.tree.nodes
+
+import org.nwapw.abacus.tree.Reducer
 
 /**
  * A tree node that represents a binary tree value operator.

core/src/main/kotlin/org/nwapw/abacus/tree/nodes/TreeValueFunctionNode.kt

@@ -1,4 +1,6 @@
-package org.nwapw.abacus.tree
+package org.nwapw.abacus.tree.nodes
+
+import org.nwapw.abacus.tree.Reducer
 
 /**
  * A tree node that represents a tree value function call.

core/src/main/kotlin/org/nwapw/abacus/tree/nodes/TreeValueUnaryNode.kt

@@ -1,4 +1,6 @@
-package org.nwapw.abacus.tree
+package org.nwapw.abacus.tree.nodes
+
+import org.nwapw.abacus.tree.Reducer
 
 /**
  * A tree node that represents a unary tree value operator.

core/src/main/kotlin/org/nwapw/abacus/tree/nodes/UnaryNode.kt

@@ -1,4 +1,4 @@
-package org.nwapw.abacus.tree
+package org.nwapw.abacus.tree.nodes
 
 /**
  * A tree node that holds a unary operation.

core/src/main/kotlin/org/nwapw/abacus/tree/nodes/VariableNode.kt

@@ -1,4 +1,6 @@
-package org.nwapw.abacus.tree
+package org.nwapw.abacus.tree.nodes
+
+import org.nwapw.abacus.tree.Reducer
 
 /**
  * A tree node that holds a placeholder variable.

core/src/test/java/org/nwapw/abacus/tests/CalculationTests.java

@@ -7,8 +7,8 @@ import org.nwapw.abacus.Abacus;
 import org.nwapw.abacus.config.Configuration;
 import org.nwapw.abacus.exception.DomainException;
 import org.nwapw.abacus.number.NumberInterface;
-import org.nwapw.abacus.plugin.StandardPlugin;
+import org.nwapw.abacus.plugin.standard.StandardPlugin;
-import org.nwapw.abacus.tree.TreeNode;
+import org.nwapw.abacus.tree.nodes.TreeNode;
 
 public class CalculationTests {
 

core/src/test/java/org/nwapw/abacus/tests/LexerTests.java

@@ -3,7 +3,7 @@ package org.nwapw.abacus.tests;
 import org.junit.Assert;
 import org.junit.Test;
 import org.nwapw.abacus.lexing.Lexer;
-import org.nwapw.abacus.lexing.pattern.Match;
+import org.nwapw.abacus.lexing.Match;
 
 import java.util.List;
 

core/src/test/java/org/nwapw/abacus/tests/RangeTests.java

@@ -5,19 +5,17 @@ import org.junit.BeforeClass;
 import org.junit.Test;
 import org.nwapw.abacus.Abacus;
 import org.nwapw.abacus.config.Configuration;
-import org.nwapw.abacus.number.NaiveNumber;
+import org.nwapw.abacus.number.promotion.PromotionFunction;
-import org.nwapw.abacus.number.NumberInterface;
+import org.nwapw.abacus.number.range.NumberRange;
-import org.nwapw.abacus.number.NumberRange;
+import org.nwapw.abacus.number.standard.NaiveNumber;
-import org.nwapw.abacus.number.PreciseNumber;
+import org.nwapw.abacus.number.standard.PreciseNumber;
-import org.nwapw.abacus.plugin.StandardPlugin;
+import org.nwapw.abacus.plugin.standard.StandardPlugin;
-
-import java.util.function.Function;
 
 public class RangeTests {
 
     private static Abacus abacus = new Abacus(new Configuration( "precise", new String[]{}));
-    private static Function<NumberInterface, NumberInterface> naivePromotion = i -> new NaiveNumber((i.toString()));
+    private static PromotionFunction naivePromotion = i -> new NaiveNumber((i.toString()));
-    private static Function<NumberInterface, NumberInterface> precisePromotion = i -> new PreciseNumber((i.toString()));
+    private static PromotionFunction precisePromotion = i -> new PreciseNumber((i.toString()));
 
     @BeforeClass
     public static void prepareTests() {

core/src/test/java/org/nwapw/abacus/tests/TokenizerTests.java

@@ -6,12 +6,15 @@ import org.junit.Test;
 import org.nwapw.abacus.Abacus;
 import org.nwapw.abacus.config.Configuration;
 import org.nwapw.abacus.context.MutableEvaluationContext;
-import org.nwapw.abacus.function.*;
+import org.nwapw.abacus.function.OperatorAssociativity;
-import org.nwapw.abacus.lexing.pattern.Match;
+import org.nwapw.abacus.function.OperatorType;
+import org.nwapw.abacus.function.interfaces.NumberFunction;
+import org.nwapw.abacus.function.interfaces.NumberOperator;
+import org.nwapw.abacus.lexing.Match;
 import org.nwapw.abacus.number.NumberInterface;
-import org.nwapw.abacus.parsing.LexerTokenizer;
+import org.nwapw.abacus.parsing.standard.LexerTokenizer;
+import org.nwapw.abacus.parsing.standard.TokenType;
 import org.nwapw.abacus.plugin.Plugin;
-import org.nwapw.abacus.tree.TokenType;
 
 import java.util.List;
 

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

@@ -16,12 +16,11 @@ import org.nwapw.abacus.exception.AbacusException;
 import org.nwapw.abacus.function.Documentation;
 import org.nwapw.abacus.function.DocumentationType;
 import org.nwapw.abacus.number.*;
-import org.nwapw.abacus.plugin.ClassFinder;
 import org.nwapw.abacus.plugin.PluginListener;
 import org.nwapw.abacus.plugin.PluginManager;
-import org.nwapw.abacus.plugin.StandardPlugin;
+import org.nwapw.abacus.plugin.standard.StandardPlugin;
-import org.nwapw.abacus.tree.EvaluationResult;
+import org.nwapw.abacus.EvaluationResult;
-import org.nwapw.abacus.tree.TreeNode;
+import org.nwapw.abacus.tree.nodes.TreeNode;
 
 import java.io.File;
 import java.io.IOException;
@@ -360,10 +359,13 @@ public class AbacusController implements PluginListener {
             if(documentationInstance == null)
                 documentationInstance = new Documentation(name, "", "", "", DocumentationType.FUNCTION);
             return documentationInstance;
-        })
+        }).collect(Collectors.toCollection(ArrayList::new)));
-                .collect(Collectors.toCollection(ArrayList::new)));
+        functionList.addAll(manager.getAllTreeValueFunctions().stream().map(name -> {
-        functionList.addAll(manager.getAllTreeValueFunctions().stream().map(name -> pluginManager.documentationFor(name, DocumentationType.TREE_VALUE_FUNCTION))
+            Documentation documentationInstance = pluginManager.documentationFor(name, DocumentationType.TREE_VALUE_FUNCTION);
-                .collect(Collectors.toCollection(ArrayList::new)));
+            if(documentationInstance == null)
+                documentationInstance = new Documentation(name, "", "", "", DocumentationType.TREE_VALUE_FUNCTION);
+            return documentationInstance;
+        }).collect(Collectors.toCollection(ArrayList::new)));
         functionList.sort(Comparator.comparing(Documentation::getCodeName));
     }
 

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

@@ -1,4 +1,4 @@
-package org.nwapw.abacus.plugin;
+package org.nwapw.abacus.fx;
 
 import java.io.File;
 import java.io.IOException;