DynamicBooleanBinderFactory.java

package com.netflix.fabricator.component.bind;

import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;

import com.google.common.base.Supplier;
import com.netflix.fabricator.ConfigurationNode;
import com.netflix.fabricator.PropertyBinder;
import com.netflix.fabricator.PropertyBinderFactory;
import com.netflix.fabricator.supplier.ListenableSupplier;

public class DynamicBooleanBinderFactory implements PropertyBinderFactory {
    private final static DynamicBooleanBinderFactory instance = new DynamicBooleanBinderFactory();
    
    public static DynamicBooleanBinderFactory get() {
        return instance;
    }

    @Override
    public PropertyBinder createBinder(final Method method, final String propertyName) {
        final Class<?>[] types = method.getParameterTypes();
        final Class<?> clazz = types[0];
        if (!clazz.isAssignableFrom(Supplier.class) && !clazz.isAssignableFrom(ListenableSupplier.class)) {
            return null;
        }
        
        ParameterizedType supplierType = (ParameterizedType)method.getGenericParameterTypes()[0];
        final Class<?> argType = (Class<?>)supplierType.getActualTypeArguments()[0];
        if (!argType.isAssignableFrom(Boolean.class) &&
            !argType.equals(boolean.class)) {
            return null;
        }
        
        return new PropertyBinder() {
            @Override
            public boolean bind(Object obj, ConfigurationNode node) throws Exception {
                Supplier<?> supplier = node.getDynamicValue(Boolean.class);
                if (supplier != null) {
                    //invoke method only when property exists. Otherwise, let builder
                    //plug-in default values
                    if (supplier.get() != null) {
                        method.invoke(obj, supplier);
                    }
                    return true;
                }
                else {
                    //Shouldn't happen
                    return false;
                }
            }
            
            public String toString() {
                return "DynamicBooleanBinderFactory["+ propertyName + "]";
            }
        };    
    }
}