Added support for temporary variables

src/main/java/com/sk89q/worldedit/expression/parser/Parser.java

@@ -33,6 +33,7 @@ import com.sk89q.worldedit.expression.lexer.tokens.Token;
 import com.sk89q.worldedit.expression.runtime.Constant;
 import com.sk89q.worldedit.expression.runtime.Functions;
 import com.sk89q.worldedit.expression.runtime.RValue;
+import com.sk89q.worldedit.expression.runtime.Variable;
 
 /**
  * Processes a list of tokens into an executable tree.
@@ -103,8 +104,13 @@ public class Parser {
                 } else {
                     RValue variable = variables.get(identifierToken.value);
                     if (variable == null) {
+                        if (next instanceof OperatorToken && ((OperatorToken)next).operator.equals("=")) {
+                            // Ugly hack to make temporary variables work while not sacrificing error reporting.
+                            variables.put(identifierToken.value, variable = new Variable(0));
+                        } else {
                             throw new ParserException(current.getPosition(), "Variable '" + identifierToken.value + "' not found");
                         }
+                    }
                     halfProcessed.add(variable);
                 }
                 expressionStart = false;