Copyright 2014 Netflix, 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.
/**
 * Copyright 2014 Netflix, 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.netflix.config;

import java.util.Collection;
import java.util.Map;

import javax.annotation.Nullable;

import com.google.common.base.Function;
import com.google.common.base.Predicate;

The default predicate (used by DynamicContextualProperty) which takes a Function to get the value of key included in the JSON blob as the input string value of DynamicContextualProperty. 
Author:
awang/**
 * The default predicate (used by {@link DynamicContextualProperty}) which takes a Function to get the value of
 * key included in the JSON blob as the input string value of {@link DynamicContextualProperty}.
 *   
 * @author awang
 *
 */
public class DefaultContextualPredicate implements Predicate<Map<String, Collection<String>>> {

    private final Function<String, String> getValueFromKeyFunction;
    
    public static final DefaultContextualPredicate PROPERTY_BASED = new DefaultContextualPredicate(new Function<String, String>() {
        @Override
        public String apply(@Nullable String input) {
            return DynamicProperty.getInstance(input).getString(); 
        }
        
    });
    
    public DefaultContextualPredicate(Function<String, String> getValueFromKeyFunction) {
        this.getValueFromKeyFunction = getValueFromKeyFunction;
    }
    
    
For each key in the passed in map, this function returns true if
 the value derived from the key using the function (passed in from the constructor) matches any of the value included for the same key in the map
 the above holds true for all keys in the map 
/**
     * For each key in the passed in map, this function returns true if
     * 
     * <li> the value derived from the key using the function (passed in from the constructor) matches <b>any</b> of the value included for the same key in the map
     * <li> the above holds true for <b>all</b> keys in the map 
     * 
     */
    @Override
    public boolean apply(@Nullable Map<String, Collection<String>> input) {
        if (null == input) {
            throw new NullPointerException();
        }
        for (Map.Entry<String, Collection<String>> entry: input.entrySet()) {
            String key = entry.getKey();                
            Collection<String> value = entry.getValue();
            if (!value.contains(getValueFromKeyFunction.apply(key))) {
                return false;
            }
        }
        return true;

    }
}