A custom Velocity directive for MyBatis to perform text substitution. Related to https://github.com/mybatis/mybatis-3/pull/331

rewritten_test_case.xml

  <sql id="sometable">
    @prefix@Table
  </sql>

  <sql id="someinclude">
    @include_target@
   </sql>

  <select id="select" lang="velocity" resultType="map">
#substitute("include_target:<include refid="org.apache.ibatis.submitted.includes.fragments.select"/>")
    <include refid="someinclude" />
#end
    field1, field2, field3
    from
#substitute("prefix:Some", "include_target:<include refid="sometable"/>")
      <include refid="someinclude" />
#end
   </select>

SubstituteDirective.java

/*
 *    Copyright 2009-2015 the original author or authors.
 *
 *    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.mybatis.scripting.velocity.use;

import java.io.IOException;
import java.io.StringWriter;
import java.io.Writer;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;

import org.apache.velocity.context.InternalContextAdapter;
import org.apache.velocity.exception.MethodInvocationException;
import org.apache.velocity.exception.ParseErrorException;
import org.apache.velocity.exception.ResourceNotFoundException;
import org.apache.velocity.runtime.directive.Directive;
import org.apache.velocity.runtime.parser.node.ASTBlock;
import org.apache.velocity.runtime.parser.node.Node;

public class SubstituteDirective extends Directive {

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

  @Override
  public int getType() {
    return BLOCK;
  }

  @Override
  public boolean render(InternalContextAdapter context, Writer writer, Node node) throws IOException, ResourceNotFoundException, ParseErrorException, MethodInvocationException {
    String body = null;
    Map<String, String> map = new HashMap<String, String>();
    for (int i = 0; i < node.jjtGetNumChildren(); i++) {
      if (node.jjtGetChild(i) != null) {
        if (node.jjtGetChild(i) instanceof ASTBlock) {
          StringWriter stringWriter = new StringWriter();
          node.jjtGetChild(i).render(context, stringWriter);
          body = stringWriter.toString();
          break;
        } else {
          String keyValueStr = String.valueOf(node.jjtGetChild(i).value(context));
          int equalPos = keyValueStr.indexOf(':');
          if (equalPos > 0) {
            String key = keyValueStr.substring(0, equalPos).trim();
            if (equalPos == keyValueStr.length() - 1)
              map.put(key, "");
            else
              map.put(key, keyValueStr.substring(equalPos + 1).trim());
          }
        }
      }
    }

    writer.write(translate(body, map));

    return true;
  }

  private String translate(String body, Map<String, String> map) {
    if (body == null || body.length() == 0 || map.isEmpty())
      return body;
    for (Entry<String, String> entry : map.entrySet()) {
      // you may want to rewrite this part for better performance
      body = body.replaceAll("@" + entry.getKey() + "@", entry.getValue());
    }
    return body;
  }
}