Merge branch 'master' into thread-safety

core/src/main/java/org/nwapw/abacus/exception/AbacusException.java

@@ -0,0 +1,9 @@
+package org.nwapw.abacus.exception;
+
+public class AbacusException extends RuntimeException {
+
+    public AbacusException(String baseMessage, String description){
+        super(baseMessage + ((description.equals("")) ? "." : (": " + description)));
+    }
+
+}

core/src/main/java/org/nwapw/abacus/exception/ComputationInterruptedException.java

@@ -1,16 +1,16 @@
-package org.nwapw.abacus.number;
+package org.nwapw.abacus.exception;
 
 /**
  * Exception thrown when the computation is interrupted by
  * the user.
  */
-public class ComputationInterruptedException extends RuntimeException {
+public class ComputationInterruptedException extends AbacusException {
 
     /**
      * Creates a new exception of this type.
      */
     public ComputationInterruptedException() {
-        super("Computation interrupted by user.");
+        super("Computation interrupted", "");
     }
 
 }

core/src/main/java/org/nwapw/abacus/exception/DomainException.java

@@ -1,24 +1,24 @@
-package org.nwapw.abacus.function;
+package org.nwapw.abacus.exception;
 
 /**
  * Exception thrown if the function parameters do not match
  * requirements.
  */
-public class DomainException extends RuntimeException {
+public class DomainException extends AbacusException {
 
     /**
      * Creates a new DomainException.
      * @param reason the reason for which the exception is thrown.
      */
     public DomainException(String reason) {
-        super(reason);
+        super("Domain error", reason);
     }
 
     /**
      * Creates a new DomainException with a default message.
      */
     public DomainException(){
-        this("Domain Error");
+        this("");
     }
 
 }

core/src/main/java/org/nwapw/abacus/exception/EvaluationException.java

@@ -1,17 +1,17 @@
-package org.nwapw.abacus.function;
+package org.nwapw.abacus.exception;
 
 /**
  * An exception thrown primarily from Tree Value operators and functions,
  * which have to deal with the result of a Reducer as well as the results
  * of Applicable.
  */
-public class EvaluationException extends RuntimeException {
+public class EvaluationException extends AbacusException {
 
     /**
      * Creates a new EvaluationException with the default string.
      */
     public EvaluationException() {
-        super("Error evaluating expression.");
+        this("");
     }
 
     /**
@@ -19,7 +19,7 @@ public class EvaluationException extends RuntimeException {
      * @param message the message string.
      */
     public EvaluationException(String message) {
-        super(message);
+        super("Evaluation error", message);
     }
 
 }

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

@@ -1,5 +1,7 @@
 package org.nwapw.abacus.number;
 
+import org.nwapw.abacus.exception.ComputationInterruptedException;
+
 /**
  * An interface used to represent a number.
  */

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

@@ -154,19 +154,20 @@ public class ShuntingYardParser implements Parser<Match<TokenType>>, PluginListe
             return new VariableNode(match.getContent());
         } else if (matchType == TokenType.FUNCTION || matchType == TokenType.TREE_VALUE_FUNCTION) {
             String functionName = match.getContent();
-            CallNode node;
-            if (matchType == TokenType.FUNCTION) {
-                node = new FunctionNode(functionName);
-            } else {
-                node = new TreeValueFunctionNode(functionName);
-            }
+            List<TreeNode> children = new ArrayList<>();
             while (!matches.isEmpty() && matches.get(0).getType() != TokenType.INTERNAL_FUNCTION_END) {
                 TreeNode argument = constructRecursive(matches);
                 if (argument == null) return null;
-                node.getChildren().add(0, argument);
+                children.add(0, argument);
             }
             if (matches.isEmpty()) return null;
             matches.remove(0);
+            CallNode node;
+            if (matchType == TokenType.FUNCTION) {
+                node = new FunctionNode(functionName, children);
+            } else {
+                node = new TreeValueFunctionNode(functionName, children);
+            }
             return node;
         }
         return null;

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

@@ -29,8 +29,7 @@ public class StandardPlugin extends Plugin {
         @Override
         public NumberInterface applyInternal(MutableEvaluationContext context, TreeNode[] params) {
             String assignTo = ((VariableNode) params[0]).getVariable();
-            NumberInterface value = params[1].reduce(context.getReducer());
-            if(value == null) throw new EvaluationException();
+            NumberInterface value = params[1].reduce(context.getInheritedReducer());
             context.setVariable(assignTo, value);
             return value;
         }
@@ -48,9 +47,7 @@ public class StandardPlugin extends Plugin {
         public NumberInterface applyInternal(MutableEvaluationContext context, TreeNode[] params) {
             String assignTo = ((VariableNode) params[0]).getVariable();
             context.setDefinition(assignTo, params[1]);
-            NumberInterface value = params[1].reduce(context.getReducer());
-            if(value == null) throw new EvaluationException();
-            return value;
+            return params[1].reduce(context.getInheritedReducer());
         }
     };
     /**