add support for CAST operation

src/de/inetsoftware/jwebassembly/module/TypeManager.java

@@ -197,6 +197,24 @@ public class TypeManager {
                         , valueOf( "java/lang/Object" ), ValueType.i32, null, ValueType.i32 ); //
     }
 
+    /**
+     * Create the FunctionName for the CAST operation and mark it as used. The function has 2 parameters (THIS,
+     * classIndex) and returns this if the type match else it throw an exception.
+     * 
+     * @return the name
+     */
+    WatCodeSyntheticFunctionName createCast() {
+        return new WatCodeSyntheticFunctionName( //
+                        "cast", "local.get 0 " // THIS
+                                        + "local.get 1 " // the class index that we search
+                                        + "call $.instanceof()V " // the synthetic signature of ArraySyntheticFunctionName
+                                        + "i32.eqz " //
+                                        + "local.get 0 " // THIS
+                                        + "return " //
+                                        + "unreachable " // TODO throw a ClassCastException if exception handling is supported
+                        , valueOf( "java/lang/Object" ), ValueType.i32, null, valueOf( "java/lang/Object" ) );
+    }
+
     /**
      * A reference to a type.
      * 

src/de/inetsoftware/jwebassembly/module/WasmCodeBuilder.java

@@ -634,11 +634,17 @@ public abstract class WasmCodeBuilder {
      *            the line number in the Java source code
      */
     protected void addStructInstruction( StructOperator op, @Nonnull String typeName, @Nullable NamedStorageType fieldName, int javaCodePos, int lineNumber ) {
-        if( op == StructOperator.INSTANCEOF ) {
-            instructions.add( new WasmConstInstruction( types.valueOf( typeName ).getClassIndex(), javaCodePos, lineNumber ) );
-            FunctionName name = options.getInstanceOf();
-            instructions.add( new WasmCallInstruction( name, javaCodePos, lineNumber, types, false ) );
-            return;
+        switch( op ) {
+            case INSTANCEOF:
+                instructions.add( new WasmConstInstruction( types.valueOf( typeName ).getClassIndex(), javaCodePos, lineNumber ) );
+                FunctionName name = options.getInstanceOf();
+                instructions.add( new WasmCallInstruction( name, javaCodePos, lineNumber, types, false ) );
+                return;
+            case CAST:
+                instructions.add( new WasmConstInstruction( types.valueOf( typeName ).getClassIndex(), javaCodePos, lineNumber ) );
+                name = options.getCast();
+                instructions.add( new WasmCallInstruction( name, javaCodePos, lineNumber, types, false ) );
+                return;
         }
         WasmStructInstruction structInst = new WasmStructInstruction( op, typeName, fieldName, javaCodePos, lineNumber, types );
         instructions.add( structInst );

src/de/inetsoftware/jwebassembly/module/WasmOptions.java

@@ -63,6 +63,8 @@ public class WasmOptions {
 
     private FunctionName instanceOf;
 
+    private FunctionName cast;
+
     /**
      * Create a new instance of options
      * 
@@ -165,4 +167,21 @@ public class WasmOptions {
         }
         return name;
     }
+
+    /**
+     * Get the FunctionName for a CAST operation and mark it as used. The function has 2 parameters (THIS, classIndex)
+     * and returns THIS or throw an exception.
+     * 
+     * @return the name
+     */
+    @Nonnull
+    FunctionName getCast() {
+        FunctionName name = cast;
+        if( name == null ) {
+            cast = name = types.createCast();
+            functions.markAsNeeded( name );
+            getInstanceOf();
+        }
+        return name;
+    }
 }

test/de/inetsoftware/jwebassembly/runtime/RuntimeErrors.java

@@ -126,19 +126,6 @@ public class RuntimeErrors {
         }
     }
 
-    @Test
-    public void checkcast() throws IOException {
-        compileErrorTest( "Unknown operator: CAST", CheckcastMethod.class );
-    }
-
-    static class CheckcastMethod {
-        @Export
-        static Integer runnable() {
-            Object obj = new Integer(0);
-            return (Integer)obj;
-        }
-    }
-
     @Test
     public void classConatnt() throws IOException {
         compileErrorTest( "Class constants are not supported.", ClassConstant.class );

test/de/inetsoftware/jwebassembly/runtime/StructsNonGC.java

@@ -55,6 +55,7 @@ public class StructsNonGC extends AbstractBaseTest {
             addParam( list, script, "instanceof1" );
             addParam( list, script, "instanceof2" );
             addParam( list, script, "instanceof3" );
+            addParam( list, script, "cast" );
         }
         rule.setTestParameters( list );
         return list;
@@ -166,6 +167,13 @@ public class StructsNonGC extends AbstractBaseTest {
             Object obj = new LinkedList();
             return obj instanceof List;
         }
+
+        @Export
+        static int cast() {
+            Object obj = new Integer(42);
+            Integer val = (Integer)obj;
+            return val.intValue();
+        }
     }
 
     interface TestDefault {