BlockTag.java

/**********************************************************************
 * Copyright (c) 2014 HubSpot Inc.
 *
 * 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.hubspot.jinjava.lib.tag;

import com.hubspot.jinjava.doc.annotations.JinjavaDoc;
import com.hubspot.jinjava.doc.annotations.JinjavaParam;
import com.hubspot.jinjava.doc.annotations.JinjavaSnippet;
import com.hubspot.jinjava.interpret.JinjavaInterpreter;
import com.hubspot.jinjava.interpret.TemplateSyntaxException;
import com.hubspot.jinjava.tree.TagNode;
import com.hubspot.jinjava.tree.output.BlockPlaceholderOutputNode;
import com.hubspot.jinjava.tree.output.OutputNode;
import com.hubspot.jinjava.util.HelperStringTokenizer;
import com.hubspot.jinjava.util.WhitespaceUtils;

/**
 * {% block name %}
 *
 */
@JinjavaDoc(
    value = "Blocks are regions in a template which can be overridden by child templates",
    params = {
        @JinjavaParam(value = "block_name", desc = "A unique name for the block that should be used in both the parent and child template")
    },
    snippets = {
        @JinjavaSnippet(
            code = "{% extends \"custom/page/web_page_basic/my_template.html\" %}\n" +
                "{% block my_sidebar %}\n" +
                "   <!--Content that will render within a block of the same name in the parent template-->\n" +
                "{% endblock %}"),
    })
public class BlockTag implements Tag {
  private static final long serialVersionUID = -2362317415797088108L;

  @Override
  public OutputNode interpretOutput(TagNode tagNode, JinjavaInterpreter interpreter) {
    HelperStringTokenizer tagData = new HelperStringTokenizer(tagNode.getHelpers());
    if (!tagData.hasNext()) {
      throw new TemplateSyntaxException(tagNode.getMaster().getImage(), "Tag 'block' expects an identifier", tagNode.getLineNumber());
    }

    String blockName = WhitespaceUtils.unquote(tagData.next());

    interpreter.addBlock(blockName, tagNode.getChildren());

    return new BlockPlaceholderOutputNode(blockName);
  }

  @Override
  public String interpret(TagNode tagNode, JinjavaInterpreter interpreter) {
    throw new UnsupportedOperationException("BlockTag must be rendered directly via interpretOutput() method");
  }

  @Override
  public String getEndTagName() {
    return "endblock";
  }

  @Override
  public String getName() {
    return "block";
  }

}