/*
* Copyright 2016 Nabarun Mondal
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package com.noga.njexl.lang.internal;
import java.lang.reflect.InvocationTargetException;
/**
* Specialized executor to get a property from an object.
* @since 2.0
*/
public final class PropertyGetExecutor extends AbstractExecutor.Get {
/** A static signature for method(). */
private static final Object[] EMPTY_PARAMS = {};
/** The property. */
private final String property;
/**
* Creates an instance by attempting discovery of the get method.
* @param is the introspector
* @param clazz the class to introspect
* @param identifier the property to get
*/
public PropertyGetExecutor(Introspector is, Class<?> clazz, String identifier) {
super(clazz, discover(is, clazz, identifier));
property = identifier;
}
/** {@inheritDoc} */
@Override
public Object getTargetProperty() {
return property;
}
/** {@inheritDoc} */
@Override
public Object execute(Object o)
throws IllegalAccessException, InvocationTargetException {
return method == null ? null : method.invoke(o, (Object[]) null);
}
/** {@inheritDoc} */
@Override
public Object tryExecute(Object o, Object identifier) {
if (o != null && method != null
&& property.equals(identifier)
&& objectClass.equals(o.getClass())) {
try {
return method.invoke(o, (Object[]) null);
} catch (InvocationTargetException xinvoke) {
return TRY_FAILED; // fail
} catch (IllegalAccessException xill) {
return TRY_FAILED;// fail
}
}
return TRY_FAILED;
}
/**
* Discovers the method for a {@link PropertyGet}.
* <p>The method to be found should be named "get{P,p}property.</p>
*@param is the introspector
*@param clazz the class to find the get method from
*@param property the property name to find
*@return the method if found, null otherwise
*/
static java.lang.reflect.Method discover(Introspector is,
final Class<?> clazz, String property) {
return discoverGet(is, "get", clazz, property);
}
/**
* Base method for boolean & object property get.
* @param is the introspector
* @param which "is" or "get" for boolean or object
* @param clazz The class being examined.
* @param property The property being addressed.
* @return The {get,is}{p,P}roperty method if one exists, null otherwise.
*/
static java.lang.reflect.Method discoverGet(Introspector is,
String which, Class<?> clazz, String property) {
// this is gross and linear, but it keeps it straightforward.
java.lang.reflect.Method method = null;
final int start = which.length(); // "get" or "is" so 3 or 2 for char case switch
// start with get<Property>
StringBuilder sb = new StringBuilder(which);
sb.append(property);
// uppercase nth char
char c = sb.charAt(start);
sb.setCharAt(start, Character.toUpperCase(c));
method = is.getMethod(clazz, sb.toString(), EMPTY_PARAMS);
//lowercase nth char
if (method == null) {
sb.setCharAt(start, Character.toLowerCase(c));
method = is.getMethod(clazz, sb.toString(), EMPTY_PARAMS);
}
return method;
}
}