/*

  * Copyright 2004-2011 the Seasar Foundation and the Others.

  *

  * 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.seasar.teeda.core.el.impl;

 import javax.faces.el.ReferenceSyntaxException;

 import org.seasar.framework.exception.EmptyRuntimeException;

 /**

  * @author shot

  */

 public class JspELParserUtil {

     private static final String JSP_OPEN_BRACE = "${";

     private static final String JSP_CLOSE_BRACE = "}";

     private JspELParserUtil() {

     }

     public static String convertToJspExpression(final String expression) {

         return convertToJspExpression(expression, "#{", "}");

     }

     public static String convertToJspExpression(final String expression,

             final String openBrace, final String closeBrace) {

         if (expression == null) {

             throw new EmptyRuntimeException("expression");

         }

         if (openBrace == null || closeBrace == null) {

             throw new ReferenceSyntaxException();

         }

         String str = expression;

         if (str.startsWith(openBrace) && str.indexOf(closeBrace) > 0) {

             int pos = str.indexOf(closeBrace);

             String s = str.substring(JSP_OPEN_BRACE.length(), pos);

             String postfix = str.substring(pos + 1);

             str = JSP_OPEN_BRACE + s + JSP_CLOSE_BRACE

                     + convertToJspExpression(postfix);

         } else {

             int pos1 = str.indexOf(openBrace);

             int pos2 = str.indexOf(closeBrace);

             if (pos1 > 0) {

                 if (pos2 > pos1) {

                     String prefix = str.substring(0, pos1);

                     String s = str.substring(pos1 + openBrace.length(), pos2);

                     String postfix = str.substring(pos2 + 1);

                     str = prefix + JSP_OPEN_BRACE + s + JSP_CLOSE_BRACE

                             + convertToJspExpression(postfix);

                 } else if (pos2 >= 0 && pos2 <= pos1) {

                     String prefix = str.substring(0, pos2 + 1);

                     String s = str.substring(pos2 + 1);

                     str = prefix + convertToJspExpression(s);

                 }

             }

         }

         return str;

     }

 }