Added a simple for loop to the expression parser.

Syntax: for (counter = first, last) { body }
Also added a test case.

src/main/java/com/sk89q/worldedit/expression/Identifiable.java

@@ -50,6 +50,7 @@ public interface Identifiable {
      * F - For
      * r - Return
      * b - Break (includes continue)
+     * S - SimpleFor
      * </pre>
      */
     public abstract char id();

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

@@ -35,9 +35,11 @@ import com.sk89q.worldedit.expression.runtime.Conditional;
 import com.sk89q.worldedit.expression.runtime.Constant;
 import com.sk89q.worldedit.expression.runtime.For;
 import com.sk89q.worldedit.expression.runtime.Functions;
+import com.sk89q.worldedit.expression.runtime.LValue;
 import com.sk89q.worldedit.expression.runtime.RValue;
 import com.sk89q.worldedit.expression.runtime.Return;
 import com.sk89q.worldedit.expression.runtime.Sequence;
+import com.sk89q.worldedit.expression.runtime.SimpleFor;
 import com.sk89q.worldedit.expression.runtime.Variable;
 import com.sk89q.worldedit.expression.runtime.While;
 
@@ -153,15 +155,50 @@ public class Parser {
                 case 'f': { // for
                     ++position;
                     consumeCharacter('(');
+                    int oldPosition = position;
                     final RValue init = parseExpression(true);
-                    consumeCharacter(';');
-                    final RValue condition = parseExpression(true);
-                    consumeCharacter(';');
-                    final RValue increment = parseExpression(true);
-                    consumeCharacter(')');
-                    final RValue body = parseStatements(true);
+                    //if ((init instanceof LValue) && )
+                    if (peek().id() == ';') {
+                        ++position;
+                        final RValue condition = parseExpression(true);
+                        consumeCharacter(';');
+                        final RValue increment = parseExpression(true);
+                        consumeCharacter(')');
+                        final RValue body = parseStatements(true);
 
-                    statements.add(new For(current.getPosition(), init, condition, increment, body));
+                        statements.add(new For(current.getPosition(), init, condition, increment, body));
+                    }
+                    else {
+                        position = oldPosition;
+
+                        final Token variableToken = peek();
+                        if (!(variableToken instanceof IdentifierToken)) {
+                            throw new ParserException(variableToken.getPosition(), "Expected identifier");
+                        }
+
+                        // In theory, I should have to create non-existant variables here.
+                        // However, the java-for parsing attempt further up already takes care of that :) 
+                        RValue variable = variables.get(((IdentifierToken) variableToken).value);
+                        if (!(variable instanceof LValue)) {
+                            throw new ParserException(variableToken.getPosition(), "Expected variable");
+                        }
+
+                        ++position;
+
+                        final Token equalsToken = peek();
+                        if (!(equalsToken instanceof OperatorToken) || !((OperatorToken) equalsToken).operator.equals("=")) {
+                            throw new ParserException(variableToken.getPosition(), "Expected '=' or a term and ';'");
+                        }
+                        ++position;
+
+                        final RValue first = parseExpression(true);
+                        consumeCharacter(',');
+                        final RValue last = parseExpression(true);
+                        consumeCharacter(')');
+                        final RValue body = parseStatements(true);
+
+                        statements.add(new SimpleFor(current.getPosition(), (LValue) variable, first, last, body));
+                    }
                     break;
                 }
 

src/main/java/com/sk89q/worldedit/expression/runtime/SimpleFor.java

@@ -0,0 +1,58 @@
+package com.sk89q.worldedit.expression.runtime;
+
+public class SimpleFor extends Node {
+    LValue counter;
+    RValue first;
+    RValue last;
+    RValue body;
+
+    public SimpleFor(int position, LValue counter, RValue first, RValue last, RValue body) {
+        super(position);
+
+        this.counter = counter;
+        this.first = first;
+        this.last = last;
+        this.body = body;
+    }
+
+    @Override
+    public double getValue() throws EvaluationException {
+        int iterations = 0;
+        double ret = 0.0;
+
+        double firstValue = first.getValue();
+        double lastValue = last.getValue();
+
+        for (double i = firstValue; i <= lastValue; ++i) {
+            if (iterations > 256) {
+                throw new EvaluationException(getPosition(), "Loop exceeded 256 iterations.");
+            }
+            ++iterations;
+
+            try {
+                counter.assign(i);
+                ret = body.getValue();
+            } catch (BreakException e) {
+                if (e.doContinue) {
+                    continue;
+                } else {
+                    break;
+                }
+            }
+        }
+
+        return ret;
+    }
+
+    @Override
+    public char id() {
+        return 'S';
+    }
+
+    @Override
+    public String toString() {
+        return "for (" + counter + " = " + first + ", " + last + ") { " + body + " }";
+    }
+
+    //TODO: optimizer
+}

src/test/java/com/sk89q/worldedit/expression/ExpressionTest.java

@@ -95,6 +95,7 @@ public class ExpressionTest {
     @Test
     public void testFor() throws ExpressionException {
         assertEquals(5, simpleEval("a=0; for (i=0; i<5; ++i) { ++a; } a"), 0);
+        assertEquals(12345, simpleEval("y=0; for (i=1,5) { y *= 10; y += i; } y"), 0);
     }
 
     private double simpleEval(String expression) throws ExpressionException {