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A Java implementation of the Amazon Ion data notation.

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/*
 * Copyright 2007-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * or in the "license" file accompanying this file. This file 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.amazon.ion.util;

import static com.amazon.ion.facet.Facets.asFacet;

import com.amazon.ion.Span;
import com.amazon.ion.SpanProvider;

/**
 * Utility methods for working with {@link Span}s.
 *
 */
public final class Spans
{
    /**
     * Attempts to get a {@link Span} from the given object, if it
     * supports {@link SpanProvider#currentSpan()}.
     *
     * @param spanProvider may be null.
     * @return null if there's not a current span.
     */
    public static Span currentSpan(Object spanProvider)
    {
        SpanProvider sp = asFacet(SpanProvider.class, spanProvider);
        Span span = (sp == null ? null : sp.currentSpan());
        return span;
    }


    /**
     * Attempts to get a {@link Span} facet from the given object, if it
     * supports {@link SpanProvider#currentSpan()}.
     *
     * @param spanProvider may be null.
     * @return null if there's not a current span supporting
     *  {@code spanFacetType}.
     */
    public static  T currentSpan(Class spanFacetType,
                                    Object spanProvider)
    {
        Span span = currentSpan(spanProvider);
        T spanFacet = asFacet(spanFacetType, span);
        return spanFacet;
    }
}