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/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch licenses this file to you 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 org.elasticsearch.script;
import java.lang.reflect.Method;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
/**
* The information necessary to compile and run a script.
*
* A {@link ScriptContext} contains the information related to a single use case and the interfaces
* and methods necessary for a {@link ScriptEngine} to implement.
* <p>
* There are two related classes which must be supplied to construct a {@link ScriptContext}.
* <p>
* The <i>CompiledType</i> is a factory class for constructing instances of a script. The
* {@link ScriptService} returns an instance of <i>CompiledType</i> when compiling a script. This class
* must be stateless so it is cacheable by the {@link ScriptService}. It must have an abstract method
* named {@code newInstance} which {@link ScriptEngine} implementations will define.
* <p>
* The <i>InstanceType</i> is a class returned by the {@code newInstance} method of the
* <i>CompiledType</i>. It is an instance of a script and may be stateful. Instances of
* the <i>InstanceType</i> may be executed multiple times by a caller with different arguments. This
* class must have an abstract method named {@code execute} which {@link ScriptEngine} implementations
* will define.
*/
public final class ScriptContext<CompiledType> {
/** A unique identifier for this context. */
public final String name;
/** A factory class for constructing instances of a script. */
public final Class<CompiledType> compiledClazz;
/** A class that is an instance of a script. */
public final Class<?> instanceClazz;
/** Construct a context with the related instance and compiled classes. */
public ScriptContext(String name, Class<CompiledType> compiledClazz) {
this.name = name;
this.compiledClazz = compiledClazz;
Method newInstanceMethod = null;
for (Method method : compiledClazz.getMethods()) {
if (method.getName().equals("newInstance")) {
if (newInstanceMethod != null) {
throw new IllegalArgumentException("Cannot have multiple newInstance methods on CompiledType class ["
+ compiledClazz.getName() + "] for script context [" + name + "]");
}
newInstanceMethod = method;
}
}
if (newInstanceMethod == null) {
throw new IllegalArgumentException("Could not find method newInstance on CompiledType class ["
+ compiledClazz.getName() + "] for script context [" + name + "]");
}
instanceClazz = newInstanceMethod.getReturnType();
}
}
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