com.sharneng.lookup.Lookups Maven / Gradle / Ivy
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/*
* Copyright (c) 2013 Original 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 com.sharneng.lookup;
import com.sharneng.lookup.fluent.Sourced;
import java.util.Collection;
import java.util.Map;
import javax.annotation.CheckForNull;
/**
* Class to hold factory methods to return the implementation of {@link Lookup}.
*
* @author Kenneth Xu
*
*/
public final class Lookups {
private Lookups() {
}
/**
* Specify the source data for the lookup to be built.
*
* @param source
* a collection of source data
* @param
* they type of the source data
* @return a fluent API interface to be continue building the lookup
*/
public static Sourced from(@CheckForNull Collection source) {
return new LookupBuilder(source);
}
/**
* Creates a lookup based on given map. This is equivalent to {@link #create(Map, Object) create(map, null)}.
*
* Please note that the created lookup uses a copy of the map passed to ensure the thread safety and performance. So
* subsequent change to the map doesn't affect the create lookup object.
*
* @param map
* the map to create the lookup
*
* @param
* type of the reference object to be looked up
* @return an implementation of {@link Lookup} that is backed by given map
*
*/
public static Lookup create(final Map map) {
return create(map, null);
}
/**
* Creates a lookup based on given map.
*
* Please note that the created lookup uses a copy of the map passed to ensure the thread safety and performance. So
* subsequent change to the map doesn't affect the create lookup object.
*
* @param map
* the map to create the lookup
* @param defaultValue
* the default value to be used if the lookup object is not found
*
* @param
* type of the reference object to be looked up
* @return an implementation of {@link Lookup} that is backed by given map
*
*/
public static Lookup create(final Map map, @CheckForNull T defaultValue) {
if (map == null) throw new IllegalArgumentException(Utils.notNull("map"));
return new MapBasedLookup(map, defaultValue);
}
/* source, string */
/**
* Create a lookup for objects in the given collection indexed by the value computed from given expression.
*
* This is equivalent to {@code from(source).notEmpty().by(expression).index()}.
*
* @param source
* a collection of source data that can be looked up.
* @param expression
* the index expression that can compute the index value from the source data
* @param
* type of the reference object to be looked up
* @return an implementation of {@link Lookup} indexed by the specified expression
*/
public static Lookup create(final Collection source, final String expression) {
return create(null, source, expression);
}
/**
* Create a two level lookup for objects in the given collection indexed by the values computed from the given
* expressions.
*
* This is equivalent to {@code from(source).notEmpty().by(expression1).by(expression2).index()}.
*
* @param source
* a collection of objects that can be looked up.
* @param expression1
* the first index expression
* @param expression2
* the second index expression
* @param
* type of the reference object to be looked up
* @return an implementation of {@link Lookup} of {@code Lookup} indexed by the specified expressions in order
*/
public static Lookup> create(final Collection source, final String expression1,
final String expression2) {
return create(null, source, expression1, expression2);
}
/**
* Create multilevel lookup for objects in the given collection indexed by the values computed from the given
* expressions.
*
* This is equivalent to {@code from(source).notEmpty().by(expressions).index()}.
*
* @param source
* a collection of objects that can be looked up.
* @param expressions
* the index expressions
* @param
* type of the reference object to be looked up
* @return an implementation of multilevel {@link Lookup} indexed by the specified expressions
*/
public static Lookup create(final Collection source, final String... expressions) {
return create(null, source, expressions);
}
/* default, source, string */
/**
* Create a lookup for objects in the given collection indexed by the value computed from given expression. The
* created lookup has default value returned when {@link Lookup#get(Object)} cannot find a reference object.
*
* This is equivalent to {@code from(source).notEmpty().defaultTo(defaultValue).by(expression).index()}.
*
* @param defaultValue
* the default value to be used if the lookup object is not found
* @param source
* a collection of objects that can be looked up.
* @param expression
* the index expression
* @param
* type of the reference object to be looked up
* @return an implementation of {@link Lookup} indexed by the specified expression
*/
public static Lookup create(@CheckForNull T defaultValue, final Collection source,
final String expression) {
return from(source).notEmpty().defaultTo(defaultValue).by(expression).index();
}
/**
* Create a two level lookup for objects in the given collection indexed by the values computed from the given
* expressions. The created lookup has default value returned when {@link Lookup#get(Object)} cannot find a
* reference object.
*
* This is equivalent to
* {@code from(source).notEmpty().defaultTo(defaultValue).by(expression1).by(expression2).index()}.
*
* @param defaultValue
* the default value to be used if the lookup object is not found
* @param source
* a collection of objects that can be looked up.
* @param expression1
* the first index expression
* @param expression2
* the second index expression
* @param
* type of the reference object to be looked up
* @return an implementation of {@link Lookup} of {@code Lookup} indexed by the specified expressions in order
*/
public static Lookup> create(@CheckForNull T defaultValue, final Collection source,
final String expression1, final String expression2) {
return from(source).notEmpty().defaultTo(defaultValue).by(expression1).by(expression2).index();
}
/**
* Create multilevel lookup for objects in the given collection indexed by the values computed from the given
* expressions. The created lookup has default value returned when {@link Lookup#get(Object)} cannot find a
* reference object.
*
* This is equivalent to {@code from(source).notEmpty().defaultTo(defaultValue).by(expressions).index()}.
*
* @param defaultValue
* the default value to be used if the lookup object is not found
* @param source
* a collection of objects that can be looked up.
* @param expressions
* the index expressions
*
* @param
* type of the reference object to be looked up
* @return an implementation of multilevel {@link Lookup} indexed by the specified expressions
*/
public static Lookup create(@CheckForNull T defaultValue, final Collection source,
final String... expressions) {
return from(source).notEmpty().defaultTo(defaultValue).by(expressions).index();
}
}