/*
 * Copyright 2002-2012 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
 *
 *      https://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.springframework.web.servlet.tags.form;

import javax.servlet.jsp.PageContext;

Utility class for generating 'id' attributes values for JSP tags. Given the name of a tag (the data bound path in most cases) returns a unique ID for that name within the current PageContext. Each request for an ID for a given name will append an ever increasing counter to the name itself. For instance, given the name 'person.name', the first request will give 'person.name1' and the second will give 'person.name2'. This supports the common use case where a set of radio or check buttons are generated for the same data field, with each button being a distinct tag instance. 
Author:
Rob Harrop, Juergen Hoeller
Since:
2.0/**
 * Utility class for generating '{@code id}' attributes values for JSP tags. Given the
 * name of a tag (the data bound path in most cases) returns a unique ID for that name within
 * the current {@link PageContext}. Each request for an ID for a given name will append an
 * ever increasing counter to the name itself. For instance, given the name '{@code person.name}',
 * the first request will give '{@code person.name1}' and the second will give
 * '{@code person.name2}'. This supports the common use case where a set of radio or check buttons
 * are generated for the same data field, with each button being a distinct tag instance.
 *
 * @author Rob Harrop
 * @author Juergen Hoeller
 * @since 2.0
 */
abstract class TagIdGenerator {

	
The prefix for all PageContext attributes created by this tag. /**
	 * The prefix for all {@link PageContext} attributes created by this tag.
	 */
	private static final String PAGE_CONTEXT_ATTRIBUTE_PREFIX = TagIdGenerator.class.getName() + ".";

	
Get the next unique ID (within the given PageContext) for the supplied name. /**
	 * Get the next unique ID (within the given {@link PageContext}) for the supplied name.
	 */
	public static String nextId(String name, PageContext pageContext) {
		String attributeName = PAGE_CONTEXT_ATTRIBUTE_PREFIX + name;
		Integer currentCount = (Integer) pageContext.getAttribute(attributeName);
		currentCount = (currentCount != null ? currentCount + 1 : 1);
		pageContext.setAttribute(attributeName, currentCount);
		return (name + currentCount);
	}

}