Improved Switch's optimizer.

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

@@ -20,6 +20,7 @@
 package com.sk89q.worldedit.expression.runtime;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -118,7 +119,50 @@ public class Switch extends Node implements RValue {
 
     @Override
     public RValue optimize() throws EvaluationException {
+        final RValue optimizedParameter = parameter.optimize();
         final List<RValue> newSequence = new ArrayList<RValue>();
+
+        if (optimizedParameter instanceof Constant) {
+            final double parameter = optimizedParameter.getValue();
+
+            final Integer index = valueMap.get(parameter);
+            if (index == null) {
+                return defaultCase == null ? new Constant(getPosition(), 0.0) : defaultCase.optimize();
+            }
+
+            boolean breakDetected = false;
+            for (int i = index; i < caseStatements.length && !breakDetected ; ++i) {
+                final RValue invokable = caseStatements[i].optimize();
+
+                if (invokable instanceof Sequence) {
+                    for (RValue subInvokable : ((Sequence) invokable).sequence) {
+                        if (subInvokable instanceof Break) {
+                            breakDetected = true;
+                            break;
+                        }
+
+                        newSequence.add(subInvokable);
+                    }
+                } else {
+                    newSequence.add(invokable);
+                }
+            }
+
+            if (defaultCase != null && !breakDetected) {
+                final RValue invokable = defaultCase.optimize();
+
+                if (invokable instanceof Sequence) {
+                    for (RValue subInvokable : ((Sequence) invokable).sequence) {
+                        newSequence.add(subInvokable);
+                    }
+                } else {
+                    newSequence.add(invokable);
+                }
+            }
+
+            return new Switch(getPosition(), optimizedParameter, Collections.singletonMap(parameter, 0), newSequence, null);
+        }
+
         final Map<Double, Integer> newValueMap = new HashMap<Double, Integer>();
 
         Map<Integer, Double> backMap = new HashMap<Integer, Double>();
@@ -143,6 +187,6 @@ public class Switch extends Node implements RValue {
             }
         }
 
-        return new Switch(getPosition(), parameter.optimize(), newValueMap, newSequence, defaultCase.optimize());
+        return new Switch(getPosition(), optimizedParameter, newValueMap, newSequence, defaultCase.optimize());
     }
 }