com.github.jknack.handlebars.io.CompositeTemplateLoader Maven / Gradle / Ivy

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The Adobe Experience Manager SDK
There is a newer version: 2024.11.18751.20241128T090041Z-241100
/**
 * Copyright (c) 2012-2015 Edgar Espina
 *
 * This file is part of Handlebars.java.
 *
 * 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.github.jknack.handlebars.io;

import static org.apache.commons.lang3.Validate.isTrue;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.nio.charset.Charset;
import java.util.Arrays;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 *  
 *  Combine two or more {@link TemplateLoader} as a single {@link TemplateLoader}.
 *  {@link TemplateLoader}s are executed in the order they are provided.
 *  
 *  
 *  Execution is as follows:
 *  
 *  
 *  If a {@link TemplateLoader} is able to resolve a {@link TemplateSource}, that
 *  {@link TemplateSource} is considered the response.
 *  If a {@link TemplateLoader} throws a {@link IOException} exception the next
 *  {@link TemplateLoader} in the chain will be used.
 *  
 *
 *  @author edgar.espina
 *  @since 1.0.0
 *
 * @deprecated com.github.jknack.handlebars.io package is deprecated and marked for removal in subsequent releases which will involve removal of the handlebars dependency in AEM.
 */
@Deprecated(since = "2024-07-10")
public class CompositeTemplateLoader implements TemplateLoader {

    /**
     * The logging system.
     */
    private static final Logger logger = LoggerFactory.getLogger(CompositeTemplateLoader.class);

    /**
     * The template loader list.
     */
    private final TemplateLoader[] delegates;

    /**
     * Creates a new {@link CompositeTemplateLoader}.
     *
     * @param loaders The template loader chain. At least two loaders must be provided.
     */
    public CompositeTemplateLoader(final TemplateLoader... loaders) {
        isTrue(loaders.length > 1, "At least two loaders are required.");
        this.delegates = loaders;
    }

    @Override
    public TemplateSource sourceAt(final String location) throws IOException {
        for (TemplateLoader delegate : delegates) {
            try {
                return delegate.sourceAt(location);
            } catch (IOException ex) {
                // try next loader in the chain.
                logger.trace("Unable to resolve: {}, trying next loader in the chain.", location);
            }
        }
        throw new FileNotFoundException(location);
    }

    @Override
    public String resolve(final String location) {
        for (TemplateLoader delegate : delegates) {
            try {
                delegate.sourceAt(location);
                return delegate.resolve(location);
            } catch (IOException ex) {
                // try next loader in the chain.
                logger.trace("Unable to resolve: {}, trying next loader in the chain.", location);
            }
        }
        throw new IllegalStateException("Can't resolve: '" + location + "'");
    }

    @Override
    public String getPrefix() {
        throw new UnsupportedOperationException();
    }

    @Override
    public String getSuffix() {
        throw new UnsupportedOperationException();
    }

    @Override
    public void setPrefix(final String prefix) {
        throw new UnsupportedOperationException();
    }

    @Override
    public void setSuffix(final String suffix) {
        throw new UnsupportedOperationException();
    }

    @Override
    public void setCharset(final Charset charset) {
        for (TemplateLoader delegate : delegates) {
            delegate.setCharset(charset);
        }
    }

    @Override
    public Charset getCharset() {
        throw new UnsupportedOperationException();
    }

    /**
     * Returns the delegates template loaders.
     *
     * @return The delegates template loaders.
     */
    public Iterable getDelegates() {
        return Arrays.asList(delegates);
    }
}