Merge pull request #264 from sk89q/expression

Expression parser changes

src/main/java/com/sk89q/worldedit/EditSession.java

@@ -2808,10 +2808,15 @@ public class EditSession {
         final RValue typeVariable = expression.getVariable("type", false);
         final RValue dataVariable = expression.getVariable("data", false);
 
+        final WorldEditExpressionEnvironment environment = new WorldEditExpressionEnvironment(this, unit, zero);
+        expression.setEnvironment(environment);
+
         final ArbitraryShape shape = new ArbitraryShape(region) {
             @Override
             protected BaseBlock getMaterial(int x, int y, int z, BaseBlock defaultMaterial) {
-                final Vector scaled = new Vector(x, y, z).subtract(zero).divide(unit);
+                final Vector current = new Vector(x, y, z);
+                environment.setCurrentBlock(current);
+                final Vector scaled = current.subtract(zero).divide(unit);
 
                 try {
                     if (expression.evaluate(scaled.getX(), scaled.getY(), scaled.getZ(), defaultMaterial.getType(), defaultMaterial.getData()) <= 0) {
@@ -2837,7 +2842,8 @@ public class EditSession {
         final RValue y = expression.getVariable("y", false);
         final RValue z = expression.getVariable("z", false);
 
-        Vector zero2 = zero.add(0.5, 0.5, 0.5);
+        final WorldEditExpressionEnvironment environment = new WorldEditExpressionEnvironment(this, unit, zero);
+        expression.setEnvironment(environment);
 
         final DoubleArrayList<BlockVector, BaseBlock> queue = new DoubleArrayList<BlockVector, BaseBlock>(false);
 
@@ -2848,13 +2854,11 @@ public class EditSession {
             // transform
             expression.evaluate(scaled.getX(), scaled.getY(), scaled.getZ());
 
-            final Vector sourceScaled = new Vector(x.getValue(), y.getValue(), z.getValue());
+            final BlockVector sourcePosition = environment.toWorld(scaled.getX(), scaled.getY(), scaled.getZ());
-
-            // unscale, unoffset, round-nearest
-            final BlockVector sourcePosition = sourceScaled.multiply(unit).add(zero2).toBlockPoint();
 
             // read block from world
-            BaseBlock material = new BaseBlock(world.getBlockType(sourcePosition), world.getBlockData(sourcePosition));
+            // TODO: use getBlock here once the reflection is out of the way
+            final BaseBlock material = new BaseBlock(world.getBlockType(sourcePosition), world.getBlockData(sourcePosition));
 
             // queue operation
             queue.put(position, material);

src/main/java/com/sk89q/worldedit/WorldEditExpressionEnvironment.java

@@ -0,0 +1,59 @@
+package com.sk89q.worldedit;
+
+import com.sk89q.worldedit.expression.runtime.ExpressionEnvironment;
+
+class WorldEditExpressionEnvironment implements ExpressionEnvironment {
+    private final Vector unit;
+    private final Vector zero2;
+    private Vector current = new Vector();
+    private EditSession editSession;
+
+    public WorldEditExpressionEnvironment(EditSession editSession, Vector unit, Vector zero) {
+        this.editSession = editSession;
+        this.unit = unit;
+        this.zero2 = zero.add(0.5, 0.5, 0.5);
+    }
+
+    public BlockVector toWorld(double x, double y, double z) {
+        // unscale, unoffset, round-nearest
+        return new Vector(x, y, z).multiply(unit).add(zero2).toBlockPoint();
+    }
+
+    public Vector toWorldRel(double x, double y, double z) {
+        return current.add(x, y, z);
+    }
+
+    @Override
+    public int getBlockType(double x, double y, double z) {
+        return editSession.getBlockType(toWorld(x, y, z));
+    }
+
+    @Override
+    public int getBlockData(double x, double y, double z) {
+        return editSession.getBlockData(toWorld(x, y, z));
+    }
+
+    @Override
+    public int getBlockTypeAbs(double x, double y, double z) {
+        return editSession.getBlockType(new Vector(x, y, z));
+    }
+
+    @Override
+    public int getBlockDataAbs(double x, double y, double z) {
+        return editSession.getBlockData(new Vector(x, y, z));
+    }
+
+    @Override
+    public int getBlockTypeRel(double x, double y, double z) {
+        return editSession.getBlockType(toWorldRel(x, y, z));
+    }
+
+    @Override
+    public int getBlockDataRel(double x, double y, double z) {
+        return editSession.getBlockData(toWorldRel(x, y, z));
+    }
+
+    public void setCurrentBlock(Vector current) {
+        this.current = current;
+    }
+}

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

@@ -24,11 +24,15 @@ import java.util.List;
 import java.util.Map;
 import java.util.Stack;
 
+import com.sk89q.worldedit.BlockVector;
+import com.sk89q.worldedit.Vector;
 import com.sk89q.worldedit.expression.lexer.Lexer;
 import com.sk89q.worldedit.expression.lexer.tokens.Token;
 import com.sk89q.worldedit.expression.parser.Parser;
+import com.sk89q.worldedit.expression.runtime.ExpressionEnvironment;
 import com.sk89q.worldedit.expression.runtime.Constant;
 import com.sk89q.worldedit.expression.runtime.EvaluationException;
+import com.sk89q.worldedit.expression.runtime.Functions;
 import com.sk89q.worldedit.expression.runtime.RValue;
 import com.sk89q.worldedit.expression.runtime.ReturnException;
 import com.sk89q.worldedit.expression.runtime.Variable;
@@ -42,7 +46,7 @@ import com.sk89q.worldedit.expression.runtime.Variable;
  * Arithmetic: +, -, *, /, % (modulo), ^ (power), - (unary), --, ++ (prefix only)
  * Comparison: <=, >=, >, <, ==, !=, ~= (near)
  *
- * Supported functions: abs, acos, asin, atan, atan2, cbrt, ceil, cos, cosh, exp, floor, ln, log, log10, max, max, min, min, rint, round, sin, sinh, sqrt, tan, tanh
+ * Supported functions: abs, acos, asin, atan, atan2, cbrt, ceil, cos, cosh, exp, floor, ln, log, log10, max, max, min, min, rint, round, sin, sinh, sqrt, tan, tanh and more. (See the Functions class or the wiki)
  *
  * Constants: e, pi
  *
@@ -63,7 +67,8 @@ public class Expression {
     private final Map<String, RValue> variables = new HashMap<String, RValue>();
     private final String[] variableNames;
     private RValue root;
-    private final Map<Integer, double[]> megabuf = new HashMap<Integer, double[]>();
+    private final Functions functions = new Functions();
+    private ExpressionEnvironment environment;
 
     public static Expression compile(String expression, String... variableNames) throws ExpressionException {
         return new Expression(expression, variableNames);
@@ -153,7 +158,15 @@ public class Expression {
         }
     }
 
-    public Map<Integer, double[]> getMegabuf() {
+    public Functions getFunctions() {
-        return megabuf;
+        return functions;
+    }
+
+    public ExpressionEnvironment getEnvironment() {
+        return environment;
+    }
+
+    public void setEnvironment(ExpressionEnvironment environment) {
+        this.environment = environment;
     }
 }

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

@@ -38,6 +38,7 @@ public interface Identifiable {
      *
      * PseudoTokens:
      * p - UnaryOperator
+     * V - UnboundVariable
      *
      * Nodes:
      * c - Constant

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

@@ -33,6 +33,7 @@ import com.sk89q.worldedit.expression.runtime.Break;
 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.Function;
 import com.sk89q.worldedit.expression.runtime.Functions;
 import com.sk89q.worldedit.expression.runtime.LValue;
 import com.sk89q.worldedit.expression.runtime.RValue;
@@ -84,6 +85,9 @@ public class Parser {
             final Token token = peek();
             throw new ParserException(token.getPosition(), "Extra token at the end of the input: " + token);
         }
+
+        ret.bindVariables(expression, false);
+
         return ret;
     }
 
@@ -267,9 +271,6 @@ public class Parser {
                 default:
                     throw new ParserException(current.getPosition(), "Unexpected keyword '" + keyword + "'");
                 }
-                switch (1) {
-                default:
-                }
 
                 break;
 
@@ -331,13 +332,12 @@ public class Parser {
                 if (next.id() == '(') {
                     halfProcessed.add(parseFunctionCall(identifierToken));
                 } else {
-                    // Ugly hack to make temporary variables work while not sacrificing error reporting.
+                    final RValue variable = expression.getVariable(identifierToken.value, false);
-                    final boolean isSimpleAssignment = next instanceof OperatorToken && ((OperatorToken) next).operator.equals("=");
-                    RValue variable = expression.getVariable(identifierToken.value, isSimpleAssignment);
                     if (variable == null) {
-                        throw new ParserException(current.getPosition(), "Variable '" + identifierToken.value + "' not found");
+                        halfProcessed.add(new UnboundVariable(identifierToken.getPosition(), identifierToken.value));
+                    } else {
+                        halfProcessed.add(variable);
                     }
-                    halfProcessed.add(variable);
                 }
                 expressionStart = false;
                 break;
@@ -388,7 +388,7 @@ public class Parser {
         return tokens.get(position);
     }
 
-    private Identifiable parseFunctionCall(IdentifierToken identifierToken) throws ParserException {
+    private Function parseFunctionCall(IdentifierToken identifierToken) throws ParserException {
         consumeCharacter('(');
 
         try {

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

@@ -0,0 +1,61 @@
+package com.sk89q.worldedit.expression.parser;
+
+import com.sk89q.worldedit.expression.Expression;
+import com.sk89q.worldedit.expression.runtime.EvaluationException;
+import com.sk89q.worldedit.expression.runtime.LValue;
+import com.sk89q.worldedit.expression.runtime.RValue;
+
+public class UnboundVariable extends PseudoToken implements LValue {
+    public final String name;
+
+    public UnboundVariable(int position, String name) {
+        super(position);
+        this.name = name;
+        // TODO Auto-generated constructor stub
+    }
+
+    @Override
+    public char id() {
+        // TODO Auto-generated method stub
+        return 'V';
+    }
+
+    @Override
+    public String toString() {
+        return "UnboundVariable(" + name + ")";
+    }
+
+    @Override
+    public double getValue() throws EvaluationException {
+        throw new EvaluationException(getPosition(), "Tried to evaluate unbound variable!");
+    }
+
+    @Override
+    public LValue optimize() throws EvaluationException {
+        throw new EvaluationException(getPosition(), "Tried to optimize unbound variable!");
+    }
+
+    @Override
+    public double assign(double value) throws EvaluationException {
+        throw new EvaluationException(getPosition(), "Tried to assign unbound variable!");
+    }
+
+    public RValue bind(Expression expression, boolean isLValue) throws ParserException {
+        final RValue variable = expression.getVariable(name, isLValue);
+        if (variable == null) {
+            throw new ParserException(getPosition(), "Variable '" + name + "' not found");
+        }
+
+        return variable;
+    }
+
+    @Override
+    public LValue bindVariables(Expression expression, boolean preferLValue) throws ParserException {
+        final RValue variable = expression.getVariable(name, preferLValue);
+        if (variable == null) {
+            throw new ParserException(getPosition(), "Variable '" + name + "' not found");
+        }
+
+        return (LValue) variable;
+    }
+}

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

@@ -19,15 +19,18 @@
 
 package com.sk89q.worldedit.expression.runtime;
 
+import com.sk89q.worldedit.expression.Expression;
+import com.sk89q.worldedit.expression.parser.ParserException;
+
 /**
  * An if/else statement or a ternary operator.
  *
  * @author TomyLobo
  */
 public class Conditional extends Node {
-    RValue condition;
+    private RValue condition;
-    RValue truePart;
+    private RValue truePart;
-    RValue falsePart;
+    private RValue falsePart;
 
     public Conditional(int position, RValue condition, RValue truePart, RValue falsePart) {
         super(position);
@@ -76,4 +79,15 @@ public class Conditional extends Node {
 
         return new Conditional(getPosition(), newCondition, truePart.optimize(), falsePart == null ? null : falsePart.optimize());
     }
+
+    @Override
+    public RValue bindVariables(Expression expression, boolean preferLValue) throws ParserException {
+        condition = condition.bindVariables(expression, false);
+        truePart = truePart.bindVariables(expression, false);
+        if (falsePart != null) {
+            falsePart = falsePart.bindVariables(expression, false);
+        }
+
+        return this;
+    }
 }

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

@@ -0,0 +1,16 @@
+package com.sk89q.worldedit.expression.runtime;
+
+import com.sk89q.worldedit.BlockVector;
+import com.sk89q.worldedit.Vector;
+
+/**
+ * Represents a way to access blocks in a world. Has to accept non-rounded coordinates.
+ */
+public interface ExpressionEnvironment {
+    int getBlockType(double x, double y, double z);
+    int getBlockData(double x, double y, double z);
+    int getBlockTypeAbs(double x, double y, double z);
+    int getBlockDataAbs(double x, double y, double z);
+    int getBlockTypeRel(double x, double y, double z);
+    int getBlockDataRel(double x, double y, double z);
+}

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

@@ -19,6 +19,9 @@
 
 package com.sk89q.worldedit.expression.runtime;
 
+import com.sk89q.worldedit.expression.Expression;
+import com.sk89q.worldedit.expression.parser.ParserException;
+
 /**
  * A Java/C-style for loop.
  *
@@ -54,6 +57,7 @@ public class For extends Node {
                 ret = body.getValue();
             } catch (BreakException e) {
                 if (e.doContinue) {
+                    //noinspection UnnecessaryContinue
                     continue;
                 } else {
                     break;
@@ -87,4 +91,14 @@ public class For extends Node {
         //return new Sequence(getPosition(), init.optimize(), new While(getPosition(), condition, new Sequence(getPosition(), body, increment), false)).optimize();
         return new For(getPosition(), init.optimize(), newCondition, increment.optimize(), body.optimize());
     }
+
+    @Override
+    public RValue bindVariables(Expression expression, boolean preferLValue) throws ParserException {
+        init = init.bindVariables(expression, false);
+        condition = condition.bindVariables(expression, false);
+        increment = increment.bindVariables(expression, false);
+        body = body.bindVariables(expression, false);
+
+        return this;
+    }
 }

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

@@ -24,6 +24,9 @@ import java.lang.annotation.RetentionPolicy;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 
+import com.sk89q.worldedit.expression.Expression;
+import com.sk89q.worldedit.expression.parser.ParserException;
+
 /**
  * Wrapper for a Java method and its arguments (other Nodes)
  *
@@ -102,10 +105,19 @@ public class Function extends Node {
 
         if (optimizable) {
             return new Constant(position, invokeMethod(method, optimizedArgs));
-        } else if (this instanceof LValueFunction) {
-            return new LValueFunction(position, method, ((LValueFunction) this).setter, optimizedArgs);
         } else {
             return new Function(position, method, optimizedArgs);
         }
     }
+
+    @Override
+    public RValue bindVariables(Expression expression, boolean preferLValue) throws ParserException {
+        final Class<?>[] parameters = method.getParameterTypes();
+        for (int i = 0; i < args.length; ++i) {
+            final boolean argumentPrefersLValue = LValue.class.isAssignableFrom(parameters[i]);
+            args[i] = args[i].bindVariables(expression, argumentPrefersLValue);
+        }
+
+        return this;
+    }
 }

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

@@ -78,6 +78,10 @@ public final class Functions {
                 return false;
             }
 
+            if (this.method.getParameterTypes().length != args.length) { // TODO: optimize
+                return false;
+            }
+
             int accum = 0;
             for (RValue argument : args) {
                 accum <<= 2;
@@ -113,7 +117,7 @@ public final class Functions {
             }
         }
 
-        throw new NoSuchMethodException();
+        throw new NoSuchMethodException(); // TODO: return null (check for side-effects first)
     }
 
     private static final Map<String, List<Overload>> functions = new HashMap<String, List<Overload>>();
@@ -273,6 +277,7 @@ public final class Functions {
 
 
     private static final Map<Integer, double[]> gmegabuf = new HashMap<Integer, double[]>();
+    private final Map<Integer, double[]> megabuf = new HashMap<Integer, double[]>();
 
     private static double[] getSubBuffer(Map<Integer, double[]> megabuf, Integer key) {
         double[] ret = megabuf.get(key);
@@ -302,18 +307,18 @@ public final class Functions {
 
     @Dynamic
     public static double megabuf(RValue index) throws EvaluationException {
-        return getBufferItem(Expression.getInstance().getMegabuf(), (int) index.getValue());
+        return getBufferItem(Expression.getInstance().getFunctions().megabuf, (int) index.getValue());
     }
 
     @Dynamic
     public static double megabuf(RValue index, double value) throws EvaluationException {
-        return setBufferItem(Expression.getInstance().getMegabuf(), (int) index.getValue(), value);
+        return setBufferItem(Expression.getInstance().getFunctions().megabuf, (int) index.getValue(), value);
     }
 
     @Dynamic
     public static double closest(RValue x, RValue y, RValue z, RValue index, RValue count, RValue stride) throws EvaluationException {
         return findClosest(
-            Expression.getInstance().getMegabuf(),
+            Expression.getInstance().getFunctions().megabuf,
             x.getValue(),
             y.getValue(),
             z.getValue(),
@@ -370,4 +375,60 @@ public final class Functions {
     public static double randint(RValue max) throws EvaluationException {
         return random.nextInt((int) Math.floor(max.getValue()));
     }
+
+
+    private static double queryInternal(LValue type, LValue data, double typeId, double dataValue) throws EvaluationException {
+        // Compare to input values and determine return value
+        final double ret = typeId == type.getValue() && typeId == type.getValue() ? 1.0 : 0.0;
+
+        type.assign(typeId);
+        data.assign(dataValue);
+
+        return ret;
+    }
+
+    @Dynamic
+    public static double query(RValue x, RValue y, RValue z, LValue type, LValue data) throws EvaluationException {
+        final double xp = x.getValue();
+        final double yp = y.getValue();
+        final double zp = z.getValue();
+
+        final ExpressionEnvironment environment = Expression.getInstance().getEnvironment();
+
+        // Read values from world
+        final double typeId = environment.getBlockType(xp, yp, zp);
+        final double dataValue = environment.getBlockData(xp, yp, zp);
+
+        return queryInternal(type, data, typeId, dataValue);
+    }
+
+    @Dynamic
+    public static double queryAbs(RValue x, RValue y, RValue z, LValue type, LValue data) throws EvaluationException {
+        final double xp = x.getValue();
+        final double yp = y.getValue();
+        final double zp = z.getValue();
+
+        final ExpressionEnvironment environment = Expression.getInstance().getEnvironment();
+
+        // Read values from world
+        final double typeId = environment.getBlockTypeAbs(xp, yp, zp);
+        final double dataValue = environment.getBlockDataAbs(xp, yp, zp);
+
+        return queryInternal(type, data, typeId, dataValue);
+    }
+
+    @Dynamic
+    public static double queryRel(RValue x, RValue y, RValue z, LValue type, LValue data) throws EvaluationException {
+        final double xp = x.getValue();
+        final double yp = y.getValue();
+        final double zp = z.getValue();
+
+        final ExpressionEnvironment environment = Expression.getInstance().getEnvironment();
+
+        // Read values from world
+        final double typeId = environment.getBlockTypeRel(xp, yp, zp);
+        final double dataValue = environment.getBlockDataRel(xp, yp, zp);
+
+        return queryInternal(type, data, typeId, dataValue);
+    }
 }

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

@@ -19,6 +19,9 @@
 
 package com.sk89q.worldedit.expression.runtime;
 
+import com.sk89q.worldedit.expression.Expression;
+import com.sk89q.worldedit.expression.parser.ParserException;
+
 /**
  * A value that can be used on the left side of an assignment.
  *
@@ -26,4 +29,8 @@ package com.sk89q.worldedit.expression.runtime;
  */
 public interface LValue extends RValue {
     public double assign(double value) throws EvaluationException;
+
+    public LValue optimize() throws EvaluationException;
+
+    public LValue bindVariables(Expression expression, boolean preferLValue) throws ParserException;
 }

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

@@ -21,6 +21,9 @@ package com.sk89q.worldedit.expression.runtime;
 
 import java.lang.reflect.Method;
 
+import com.sk89q.worldedit.expression.Expression;
+import com.sk89q.worldedit.expression.parser.ParserException;
+
 /**
  * Wrapper for a pair of Java methods and their arguments (other Nodes), forming an LValue
  *
@@ -28,10 +31,11 @@ import java.lang.reflect.Method;
  */
 public class LValueFunction extends Function implements LValue {
     private final Object[] setterArgs;
-    final Method setter;
+    private final Method setter;
 
     LValueFunction(int position, Method getter, Method setter, RValue... args) {
         super(position, getter, args);
+        assert (getter.isAnnotationPresent(Dynamic.class));
 
         setterArgs = new Object[args.length + 1];
         System.arraycopy(args, 0, setterArgs, 0, args.length);
@@ -48,4 +52,25 @@ public class LValueFunction extends Function implements LValue {
         setterArgs[setterArgs.length - 1] = value;
         return invokeMethod(setter, setterArgs);
     }
+
+    @Override
+    public LValue optimize() throws EvaluationException {
+        final RValue optimized = super.optimize();
+        if (optimized == this) {
+            return this;
+        }
+
+        if (optimized instanceof Function) {
+            return new LValueFunction(optimized.getPosition(), method, setter, ((Function) optimized).args);
+        }
+
+        return (LValue) optimized;
+    }
+
+    @Override
+    public LValue bindVariables(Expression expression, boolean preferLValue) throws ParserException {
+        super.bindVariables(expression, preferLValue);
+
+        return this;
+    }
 }

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

@@ -19,6 +19,9 @@
 
 package com.sk89q.worldedit.expression.runtime;
 
+import com.sk89q.worldedit.expression.Expression;
+import com.sk89q.worldedit.expression.parser.ParserException;
+
 /**
  * A node in the execution tree of an expression.
  *
@@ -42,4 +45,9 @@ public abstract class Node implements RValue {
     public final int getPosition() {
         return position;
     }
+
+    @Override
+    public RValue bindVariables(Expression expression, boolean preferLValue) throws ParserException {
+        return this;
+    }
 }

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

@@ -19,7 +19,9 @@
 
 package com.sk89q.worldedit.expression.runtime;
 
+import com.sk89q.worldedit.expression.Expression;
 import com.sk89q.worldedit.expression.Identifiable;
+import com.sk89q.worldedit.expression.parser.ParserException;
 
 /**
  * A value that can be used on the right side of an assignment.
@@ -30,4 +32,6 @@ public interface RValue extends Identifiable {
     public double getValue() throws EvaluationException;
 
     public RValue optimize() throws EvaluationException;
+
+    public RValue bindVariables(Expression expression, boolean preferLValue) throws ParserException;
 }

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

@@ -19,6 +19,9 @@
 
 package com.sk89q.worldedit.expression.runtime;
 
+import com.sk89q.worldedit.expression.Expression;
+import com.sk89q.worldedit.expression.parser.ParserException;
+
 /**
  * A return statement.
  *
@@ -47,4 +50,11 @@ public class Return extends Node {
     public String toString() {
         return "return " + value;
     }
+
+    @Override
+    public RValue bindVariables(Expression expression, boolean preferLValue) throws ParserException {
+        value = value.bindVariables(expression, false);
+
+        return this;
+    }
 }

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

@@ -22,6 +22,9 @@ package com.sk89q.worldedit.expression.runtime;
 import java.util.ArrayList;
 import java.util.List;
 
+import com.sk89q.worldedit.expression.Expression;
+import com.sk89q.worldedit.expression.parser.ParserException;
+
 /**
  * A sequence of operations, usually separated by semicolons in the input stream.
  *
@@ -94,4 +97,13 @@ public class Sequence extends Node {
 
         return new Sequence(getPosition(), newSequence.toArray(new RValue[newSequence.size()]));
     }
+
+    @Override
+    public RValue bindVariables(Expression expression, boolean preferLValue) throws ParserException {
+        for (int i = 0; i < sequence.length; ++i) {
+            sequence[i] = sequence[i].bindVariables(expression, false);
+        }
+
+        return this;
+    }
 }

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

@@ -19,6 +19,9 @@
 
 package com.sk89q.worldedit.expression.runtime;
 
+import com.sk89q.worldedit.expression.Expression;
+import com.sk89q.worldedit.expression.parser.ParserException;
+
 /**
  * A simple-style for loop.
  *
@@ -58,6 +61,7 @@ public class SimpleFor extends Node {
                 ret = body.getValue();
             } catch (BreakException e) {
                 if (e.doContinue) {
+                    //noinspection UnnecessaryContinue
                     continue;
                 } else {
                     break;
@@ -84,4 +88,14 @@ public class SimpleFor extends Node {
 
         return new SimpleFor(getPosition(), (LValue) counter.optimize(), first.optimize(), last.optimize(), body.optimize());
     }
+
+    @Override
+    public RValue bindVariables(Expression expression, boolean preferLValue) throws ParserException {
+        counter = counter.bindVariables(expression, true);
+        first = first.bindVariables(expression, false);
+        last = last.bindVariables(expression, false);
+        body = body.bindVariables(expression, false);
+
+        return this;
+    }
 }

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

@@ -26,16 +26,19 @@ import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 
+import com.sk89q.worldedit.expression.Expression;
+import com.sk89q.worldedit.expression.parser.ParserException;
+
 /**
  * A switch/case construct.
  *
  * @author TomyLobo
  */
 public class Switch extends Node implements RValue {
-    private final RValue parameter;
+    private RValue parameter;
     private final Map<Double, Integer> valueMap;
     private final RValue[] caseStatements;
-    private final RValue defaultCase;
+    private RValue defaultCase;
 
     public Switch(int position, RValue parameter, List<Double> values, List<RValue> caseStatements, RValue defaultCase) {
         this(position, parameter, invertList(values), caseStatements, defaultCase);
@@ -154,9 +157,7 @@ public class Switch extends Node implements RValue {
                 final RValue invokable = defaultCase.optimize();
 
                 if (invokable instanceof Sequence) {
-                    for (RValue subInvokable : ((Sequence) invokable).sequence) {
+                    Collections.addAll(newSequence, ((Sequence) invokable).sequence);
-                        newSequence.add(subInvokable);
-                    }
                 } else {
                     newSequence.add(invokable);
                 }
@@ -191,4 +192,17 @@ public class Switch extends Node implements RValue {
 
         return new Switch(getPosition(), optimizedParameter, newValueMap, newSequence, defaultCase.optimize());
     }
+
+    @Override
+    public RValue bindVariables(Expression expression, boolean preferLValue) throws ParserException {
+        parameter = parameter.bindVariables(expression, false);
+
+        for (int i = 0; i < caseStatements.length; ++i) {
+            caseStatements[i] = caseStatements[i].bindVariables(expression, false);
+        }
+
+        defaultCase = defaultCase.bindVariables(expression, false);
+
+        return this;
+    }
 }

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

@@ -19,6 +19,9 @@
 
 package com.sk89q.worldedit.expression.runtime;
 
+import com.sk89q.worldedit.expression.Expression;
+import com.sk89q.worldedit.expression.parser.ParserException;
+
 /**
  * A variable.
  *
@@ -51,4 +54,14 @@ public final class Variable extends Node implements LValue {
     public double assign(double value) {
         return this.value = value;
     }
+
+    @Override
+    public LValue optimize() throws EvaluationException {
+        return this;
+    }
+
+    @Override
+    public LValue bindVariables(Expression expression, boolean preferLValue) throws ParserException {
+        return this;
+    }
 }

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

@@ -19,6 +19,9 @@
 
 package com.sk89q.worldedit.expression.runtime;
 
+import com.sk89q.worldedit.expression.Expression;
+import com.sk89q.worldedit.expression.parser.ParserException;
+
 /**
  * A while loop.
  *
@@ -70,6 +73,7 @@ public class While extends Node {
                     ret = body.getValue();
                 } catch (BreakException e) {
                     if (e.doContinue) {
+                        //noinspection UnnecessaryContinue
                         continue;
                     } else {
                         break;
@@ -112,4 +116,12 @@ public class While extends Node {
 
         return new While(getPosition(), newCondition, body.optimize(), footChecked);
     }
+
+    @Override
+    public RValue bindVariables(Expression expression, boolean preferLValue) throws ParserException {
+        condition = condition.bindVariables(expression, false);
+        body = body.bindVariables(expression, false);
+
+        return this;
+    }
 }