/*
 * Copyright 2002-2018 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.springframework.web.bind.annotation;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import org.springframework.core.annotation.AliasFor;

Annotation which indicates that a method parameter should be bound to a name-value pair within a path segment. Supported for RequestMapping annotated handler methods. 
If the method parameter type is Map and a matrix variable name is specified, then the matrix variable value is converted to a Map assuming an appropriate conversion strategy is available. 
If the method parameter is Map<String, String> or MultiValueMap<String, String> and a variable name is not specified, then the map is populated with all matrix variable names and values. 
Author:
Rossen Stoyanchev, Sam Brannen
Since:
3.2/**
 * Annotation which indicates that a method parameter should be bound to a
 * name-value pair within a path segment. Supported for {@link RequestMapping}
 * annotated handler methods.
 *
 * <p>If the method parameter type is {@link java.util.Map} and a matrix variable
 * name is specified, then the matrix variable value is converted to a
 * {@link java.util.Map} assuming an appropriate conversion strategy is available.
 *
 * <p>If the method parameter is {@link java.util.Map Map&lt;String, String&gt;} or
 * {@link org.springframework.util.MultiValueMap MultiValueMap&lt;String, String&gt;}
 * and a variable name is not specified, then the map is populated with all
 * matrix variable names and values.
 *
 * @author Rossen Stoyanchev
 * @author Sam Brannen
 * @since 3.2
 */
@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface MatrixVariable {

	
Alias for name. /**
	 * Alias for {@link #name}.
	 */
	@AliasFor("name")
	String value() default "";

	
The name of the matrix variable.
See Also:
value
Since:
4.2/**
	 * The name of the matrix variable.
	 * @since 4.2
	 * @see #value
	 */
	@AliasFor("value")
	String name() default "";

	
The name of the URI path variable where the matrix variable is located,
if necessary for disambiguation (e.g. a matrix variable with the same
name present in more than one path segment).
/**
	 * The name of the URI path variable where the matrix variable is located,
	 * if necessary for disambiguation (e.g. a matrix variable with the same
	 * name present in more than one path segment).
	 */
	String pathVar() default ValueConstants.DEFAULT_NONE;

	
Whether the matrix variable is required.
Default is true, leading to an exception being thrown in case the variable is missing in the request. Switch this to false if you prefer a null if the variable is missing. 
Alternatively, provide a defaultValue, which implicitly sets this flag to false. /**
	 * Whether the matrix variable is required.
	 * <p>Default is {@code true}, leading to an exception being thrown in
	 * case the variable is missing in the request. Switch this to {@code false}
	 * if you prefer a {@code null} if the variable is missing.
	 * <p>Alternatively, provide a {@link #defaultValue}, which implicitly sets
	 * this flag to {@code false}.
	 */
	boolean required() default true;

	
The default value to use as a fallback.
Supplying a default value implicitly sets required to false. /**
	 * The default value to use as a fallback.
	 * <p>Supplying a default value implicitly sets {@link #required} to
	 * {@code false}.
	 */
	String defaultValue() default ValueConstants.DEFAULT_NONE;

}