package org.simantics.scl.compiler.constants.generic;

import java.util.ArrayList;

import org.cojen.classfile.TypeDesc;
import org.objectweb.asm.Label;
import org.simantics.scl.compiler.internal.codegen.utils.Constants;
import org.simantics.scl.compiler.internal.codegen.utils.MethodBuilder;

public enum ConvertToListFilter implements OutputFilter {
    INSTANCE;

    private static final TypeDesc ARRAY_LIST = TypeDesc.forClass(ArrayList.class);
    private static final TypeDesc[] CONVERSION_PARAMS =
            new TypeDesc[] {Constants.COLLECTION};
    
    @Override
    public void filter(MethodBuilder mb) {
        Label conversionNeeded = mb.createLabel();
        Label endFilter = mb.createLabel();
        
        mb.dup();
        mb.instanceOf(Constants.LIST);        
        mb.ifZeroComparisonBranch(conversionNeeded, "==");
        
        // no conversion needed
        mb.checkCast(Constants.LIST);
        mb.branch(endFilter);
        
        // conversion needed
        mb.setLocation(conversionNeeded);
        
        mb.newObject(ARRAY_LIST);
        mb.dupX1();
        mb.swap();
        mb.invokeConstructor(ARRAY_LIST, CONVERSION_PARAMS);
        
        // end
        mb.setLocation(endFilter);
    }

}