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Grails Web Application Framework

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/*
 * Copyright 2013 SpringSource
 *
 * 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 org.grails.async.factory

import grails.async.Promise
import groovy.transform.CompileStatic

import java.util.concurrent.TimeUnit

/**
 * A bound promise is a promise which is already resolved and doesn't require any asynchronous processing to calculate the value
 *
 * @author Graeme Rocher
 * @since 2.3
 */
@CompileStatic
class BoundPromise implements Promise {
    def T value

    BoundPromise(T value) {
        this.value = value
    }

    T get() throws Throwable {
        if (value instanceof Throwable) {
            throw value
        }
        return value
    }

    T get(long timeout, TimeUnit units) throws Throwable {
        return get()
    }

    Promise onComplete(Closure callable) {
        if (!(value instanceof Throwable)) {
            callable.call(value)
        }
        return this
    }

    Promise onError(Closure callable) {
        if (value instanceof Throwable) {
            callable.call(value)
        }
        return this

    }

    Promise then(Closure callable) {
        if (!(value instanceof Throwable)) {
            try {
                final value = callable.call(value)
                return new BoundPromise(value)
            } catch (Throwable e) {
                return new BoundPromise(e)
            }
        }
        else {
            return this
        }
    }

    Promise leftShift(Closure callable) {
        then callable
    }
}