/*
* 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 com.noga.njexl.lang.internal.introspection.MethodKey;
import com.noga.njexl.lang.introspection.JexlPropertyGet;
import com.noga.njexl.lang.introspection.JexlPropertySet;
import com.noga.njexl.lang.introspection.JexlMethod;
import java.lang.reflect.InvocationTargetException;
/**
* Abstract class that is used to execute an arbitrary
* method that is introspected. This is the superclass
* for all other AbstractExecutor classes.
*
* @since 1.0
*/
public abstract class AbstractExecutor {
/** A marker for invocation failures in tryInvoke. */
public static final Object TRY_FAILED = new Object() {
@Override
public String toString() {
return "tryExecute failed";
}
};
/**
* A helper to initialize the marker methods (array.get, list.get, etc...).
* @param clazz the class to introspect
* @param name the name of the method
* @param parms the parameters
* @return the method
*/
static java.lang.reflect.Method initMarker(Class<?> clazz, String name, Class<?>... parms) {
try {
return clazz.getMethod(name, parms);
} catch (Exception xnever) {
throw new Error(xnever);
}
}
/**
* Creates an arguments array.
* @param args the list of arguments
* @return the arguments array
*/
static Object[] makeArgs(Object... args) {
return args;
}
/** The class this executor applies to. */
protected final Class<?> objectClass;
/** Method to be executed. */
protected final java.lang.reflect.Method method;
/**
* Default and sole constructor.
* @param theClass the class this executor applies to
* @param theMethod the method held by this executor
*/
protected AbstractExecutor(Class<?> theClass, java.lang.reflect.Method theMethod) {
objectClass = theClass;
method = theMethod;
}
/** {@inheritDoc} */
@Override
public boolean equals(Object obj) {
return this == obj || (obj instanceof AbstractExecutor && equals((AbstractExecutor) obj));
}
/** {@inheritDoc} */
@Override
public int hashCode() {
return method.hashCode();
}
/**
* Indicates whether some other executor is equivalent to this one.
* @param arg the other executor to check
* @return true if both executors are equivalent, false otherwise
*/
public boolean equals(AbstractExecutor arg) {
// common equality check
if (!this.getClass().equals(arg.getClass())) {
return false;
}
if (!this.getMethod().equals(arg.getMethod())) {
return false;
}
if (!this.getTargetClass().equals(arg.getTargetClass())) {
return false;
}
// specific equality check
Object lhsp = this.getTargetProperty();
Object rhsp = arg.getTargetProperty();
if (lhsp == null && rhsp == null) {
return true;
}
if (lhsp != null && rhsp != null) {
return lhsp.equals(rhsp);
}
return false;
}
/**
* Tell whether the executor is alive by looking
* at the value of the method.
*
* @return boolean Whether the executor is alive.
*/
public final boolean isAlive() {
return (method != null);
}
/**
* Specifies if this executor is cacheable and able to be reused for this
* class of object it was returned for.
*
* @return true if can be reused for this class, false if not
*/
public boolean isCacheable() {
return method != null;
}
/**
* Gets the method to be executed or used as a marker.
* @return Method The method used by execute in derived classes.
*/
public final java.lang.reflect.Method getMethod() {
return method;
}
/**
* Gets the object class targeted by this executor.
* @return the target object class
*/
public final Class<?> getTargetClass() {
return objectClass;
}
/**
* Gets the property targeted by this executor.
* @return the target property
*/
public Object getTargetProperty() {
return null;
}
/**
* Gets the method name used.
* @return method name
*/
public final String getMethodName() {
return method.getName();
}
/**
* Checks whether a tryExecute failed or not.
* @param exec the value returned by tryExecute
* @return true if tryExecute failed, false otherwise
*/
public final boolean tryFailed(Object exec) {
return exec == TRY_FAILED;
}
/**
* Abstract class that is used to execute an arbitrary 'get' method.
*/
public abstract static class Get extends AbstractExecutor implements JexlPropertyGet {
/**
* Default and sole constructor.
* @param theClass the class this executor applies to
* @param theMethod the method held by this executor
*/
protected Get(Class<?> theClass, java.lang.reflect.Method theMethod) {
super(theClass, theMethod);
}
/** {@inheritDoc} */
public final Object invoke(Object obj) throws Exception {
return execute(obj);
}
/** {@inheritDoc} */
public final Object tryInvoke(Object obj, Object key) {
return tryExecute(obj, key);
}
/**
* Gets the property value from an object.
*
* @param obj The object to get the property from.
* @return The property value.
* @throws IllegalAccessException Method is inaccessible.
* @throws InvocationTargetException Method body throws an exception.
*/
public abstract Object execute(Object obj)
throws IllegalAccessException, InvocationTargetException;
/**
* Tries to reuse this executor, checking that it is compatible with
* the actual set of arguments.
* <p>Compatibility means that:
* <code>o</code> must be of the same class as this executor's
* target class and
* <code>property</code> must be of the same class as this
* executor's target property (for list and map based executors) and have the same
* value (for other types).</p>
* @param obj The object to get the property from.
* @param key The property to get from the object.
* @return The property value or TRY_FAILED if checking failed.
*/
public Object tryExecute(Object obj, Object key) {
return TRY_FAILED;
}
}
/**
* Abstract class that is used to execute an arbitrary 'set' method.
*/
public abstract static class Set extends AbstractExecutor implements JexlPropertySet {
/**
* Default and sole constructor.
* @param theClass the class this executor applies to
* @param theMethod the method held by this executor
*/
protected Set(Class<?> theClass, java.lang.reflect.Method theMethod) {
super(theClass, theMethod);
}
/** {@inheritDoc} */
public final Object invoke(Object obj, Object arg) throws Exception {
return execute(obj, arg);
}
/** {@inheritDoc} */
public final Object tryInvoke(Object obj, Object key, Object value) {
return tryExecute(obj, key, value);
}
/**
* Sets the property value of an object.
*
* @param obj The object to set the property in.
* @param value The value.
* @return The return value.
* @throws IllegalAccessException Method is inaccessible.
* @throws InvocationTargetException Method body throws an exception.
*/
public abstract Object execute(Object obj, Object value)
throws IllegalAccessException, InvocationTargetException;
/**
* Tries to reuse this executor, checking that it is compatible with
* the actual set of arguments.
* <p>Compatibility means that:
* <code>o</code> must be of the same class as this executor's
* target class,
* <code>property</code> must be of the same class as this
* executor's target property (for list and map based executors) and have the same
* value (for other types)
* and that <code>arg</code> must be a valid argument for this
* executor underlying method.</p>
* @param obj The object to invoke the method from.
* @param key The property to set in the object.
* @param value The value to use as the property value.
* @return The return value or TRY_FAILED if checking failed.
*/
public Object tryExecute(Object obj, Object key, Object value) {
return TRY_FAILED;
}
}
/**
* Abstract class that is used to execute an arbitrary method.
*/
public abstract static class Method extends AbstractExecutor implements JexlMethod {
/**
* A helper class to pass the method & parameters.
*/
protected static final class Parameter {
/** The method. */
private final java.lang.reflect.Method method;
/** The method key. */
private final MethodKey key;
/** Creates an instance.
* @param m the method
* @param k the method key
*/
public Parameter(java.lang.reflect.Method m, MethodKey k) {
method = m;
key = k;
}
}
/** The method key discovered from the arguments. */
protected final MethodKey key;
/**
* Creates a new instance.
* @param c the class this executor applies to
* @param km the method and MethodKey to encapsulate.
*/
protected Method(Class<?> c, Parameter km) {
super(c, km.method);
key = km.key;
}
/** {@inheritDoc} */
public final Object invoke(Object obj, Object[] params) throws Exception {
return execute(obj, params);
}
/** {@inheritDoc} */
public final Object tryInvoke(String name, Object obj, Object[] params) {
return tryExecute(name, obj, params);
}
/** {@inheritDoc} */
@Override
public Object getTargetProperty() {
return key;
}
/**
* Returns the return type of the method invoked.
* @return return type
*/
public final Class<?> getReturnType() {
return method.getReturnType();
}
/**
* Invokes the method to be executed.
*
* @param obj the object to invoke the method upon
* @param args the method arguments
* @return the result of the method invocation
* @throws IllegalAccessException Method is inaccessible.
* @throws InvocationTargetException Method body throws an exception.
*/
public abstract Object execute(Object obj, Object[] args)
throws IllegalAccessException, InvocationTargetException;
/**
* Tries to reuse this executor, checking that it is compatible with
* the actual set of arguments.
* @param obj the object to invoke the method upon
* @param name the method name
* @param args the method arguments
* @return the result of the method invocation or TRY_FAILED if checking failed.
*/
public Object tryExecute(String name, Object obj, Object[] args){
return TRY_FAILED;
}
}
}