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mariofuscomariofusco
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dsl chapter
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‎src/main/java/lambdasinaction/dsl/Grouping.java

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/*
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* Copyright 2005 JBoss Inc
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package lambdasinaction.dsl;
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import lambdasinaction.chap5.Dish;
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import java.util.List;
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import java.util.Map;
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import java.util.function.Function;
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import java.util.stream.Collector;
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import static java.util.stream.Collectors.groupingBy;
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import static lambdasinaction.chap5.Dish.menu;
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import static lambdasinaction.dsl.Grouping.GroupingBuilder.groupOn;
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public class Grouping {
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enum CaloricLevel { DIET, NORMAL, FAT };
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public static void main(String ... args) {
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System.out.println("Dishes grouped by type and caloric level: " + groupDishedByTypeAndCaloricLevel2());
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System.out.println("Dishes grouped by type and caloric level: " + groupDishedByTypeAndCaloricLevel3());
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}
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private static CaloricLevel getCaloricLevel( Dish dish ) {
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if (dish.getCalories() <= 400) return CaloricLevel.DIET;
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else if (dish.getCalories() <= 700) return CaloricLevel.NORMAL;
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else return CaloricLevel.FAT;
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}
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private static Map<Dish.Type, Map<CaloricLevel, List<Dish>>> groupDishedByTypeAndCaloricLevel2() {
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return menu.stream().collect(
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twoLevelGroupingBy(Dish::getType, dish -> getCaloricLevel( dish ) )
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);
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}
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public static <A, B, T> Collector<T, ?, Map<A, Map<B, List<T>>>> twoLevelGroupingBy(Function<? super T, ? extends A> f1, Function<? super T, ? extends B> f2) {
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return groupingBy(f1, groupingBy(f2));
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}
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private static Map<Dish.Type, Map<CaloricLevel, List<Dish>>> groupDishedByTypeAndCaloricLevel3() {
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Collector<? super Dish, ?, Map<Dish.Type, Map<CaloricLevel, List<Dish>>>> c = groupOn( ( Dish dish ) -> getCaloricLevel( dish ) ).after( Dish::getType ).get();
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return menu.stream().collect( c );
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}
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public static class GroupingBuilder<T, D, K> {
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private final Collector<? super T, ?, Map<K, D>> collector;
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public GroupingBuilder( Collector<? super T, ?, Map<K, D>> collector ) {
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this.collector = collector;
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}
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public Collector<? super T, ?, Map<K, D>> get() {
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return collector;
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}
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public <J> GroupingBuilder<T, Map<K, D>, J> after(Function<? super T, ? extends J> classifier) {
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return new GroupingBuilder<>( groupingBy( classifier, collector ) );
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}
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public static <T, D, K> GroupingBuilder<T, List<T>, K> groupOn(Function<? super T, ? extends K> classifier) {
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return new GroupingBuilder<>( groupingBy( classifier ) );
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}
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}
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}

‎src/main/java/lambdasinaction/dsl/LambdaOrderBuilder.java

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/*
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* Copyright 2005 JBoss Inc
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package lambdasinaction.dsl;
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import lambdasinaction.dsl.model.Order;
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import lambdasinaction.dsl.model.Stock;
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import lambdasinaction.dsl.model.Trade;
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import java.util.function.Consumer;
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public class LambdaOrderBuilder {
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private Order order = new Order();
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public static Order order(Consumer<LambdaOrderBuilder> consumer) {
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LambdaOrderBuilder builder = new LambdaOrderBuilder();
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consumer.accept( builder );
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return builder.order;
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}
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public void forCustomer(String customer) {
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order.setCustomer( customer );
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}
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public void buy(Consumer<TradeBuilder> consumer) {
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trade( consumer, Trade.Type.BUY );
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}
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public void sell(Consumer<TradeBuilder> consumer) {
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trade( consumer, Trade.Type.SELL );
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}
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private void trade( Consumer<TradeBuilder> consumer, Trade.Type type ) {
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TradeBuilder builder = new TradeBuilder();
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builder.trade.setType( type );
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consumer.accept( builder );
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order.addTrade( builder.trade );
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}
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public static class TradeBuilder {
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private Trade trade = new Trade();
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public void quantity(int quantity) {
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trade.setQuantity( quantity );
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}
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public void price(double price) {
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trade.setPrice( price );
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}
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public void stock(Consumer<StockBuilder> consumer) {
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StockBuilder builder = new StockBuilder();
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consumer.accept( builder );
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trade.setStock( builder.stock );
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}
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}
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public static class StockBuilder {
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private Stock stock = new Stock();
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public void symbol(String symbol) {
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stock.setSymbol( symbol );
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}
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public void market(String market) {
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stock.setMarket( market );
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}
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}
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}

‎src/main/java/lambdasinaction/dsl/Main.java

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/*
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* Copyright 2005 JBoss Inc
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package lambdasinaction.dsl;
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import lambdasinaction.dsl.model.Order;
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import lambdasinaction.dsl.model.Stock;
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import lambdasinaction.dsl.model.Trade;
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import static lambdasinaction.dsl.MethodChainingOrderBuilder.forCustomer;
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import static lambdasinaction.dsl.NestedFunctionOrderBuilder.*;
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public class Main {
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public void plain() {
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Order order = new Order();
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order.setCustomer( "BigBank" );
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Trade trade1 = new Trade();
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trade1.setType( Trade.Type.BUY );
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Stock stock1 = new Stock();
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stock1.setSymbol( "IBM" );
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stock1.setMarket( "NYSE" );
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trade1.setStock( stock1 );
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trade1.setPrice( 125.00 );
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trade1.setQuantity( 80 );
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order.addTrade( trade1 );
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Trade trade2 = new Trade();
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trade2.setType( Trade.Type.BUY );
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Stock stock2 = new Stock();
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stock2.setSymbol( "GOOGLE" );
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stock2.setMarket( "NASDAQ" );
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trade2.setStock( stock2 );
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trade2.setPrice( 375.00 );
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trade2.setQuantity( 50 );
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order.addTrade( trade2 );
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}
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public void methodChaining() {
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Order order = forCustomer( "BigBank" )
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.buy( 80 ).stock( "IBM" ).on( "NYSE" ).at( 125.00 )
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.sell( 50 ).stock( "GOOGLE" ).on( "NASDAQ" ).at( 375.00 )
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.end();
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}
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public void nestedFunction() {
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Order order = order("BigBank",
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buy(80,
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stock( "IBM", on( "NYSE" ) ),
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at(125.00)),
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sell(50,
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stock("GOOGLE", on("NASDAQ")),
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at(375.00))
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);
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}
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public void lambda() {
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Order order = LambdaOrderBuilder.order( o -> {
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o.forCustomer( "BigBank" );
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o.buy( t -> {
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t.quantity( 80 );
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t.price( 125.00 );
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t.stock( s -> {
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s.symbol( "IBM" );
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s.market( "NYSE" );
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} );
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});
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o.sell( t -> {
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t.quantity( 50 );
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t.price( 375.00 );
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t.stock( s -> {
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s.symbol( "GOOGLE" );
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s.market( "NASDAQ" );
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} );
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});
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} );
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}
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}

‎src/main/java/lambdasinaction/dsl/MethodChainingOrderBuilder.java

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/*
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* Copyright 2005 JBoss Inc
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package lambdasinaction.dsl;
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import lambdasinaction.dsl.model.Order;
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import lambdasinaction.dsl.model.Stock;
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import lambdasinaction.dsl.model.Trade;
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public class MethodChainingOrderBuilder {
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public final Order order = new Order();
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private MethodChainingOrderBuilder(String customer) {
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order.setCustomer( customer );
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}
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public static MethodChainingOrderBuilder forCustomer( String customer ) {
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return new MethodChainingOrderBuilder(customer);
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}
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public Order end() {
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return order;
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}
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public TradeBuilder buy(int quantity) {
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return new TradeBuilder( this, Trade.Type.BUY, quantity );
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}
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public TradeBuilder sell(int quantity) {
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return new TradeBuilder( this, Trade.Type.SELL, quantity );
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}
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private MethodChainingOrderBuilder addTrade(Trade trade) {
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order.addTrade( trade );
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return this;
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}
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public static class TradeBuilder {
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private final MethodChainingOrderBuilder builder;
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public final Trade trade = new Trade();
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private TradeBuilder(MethodChainingOrderBuilder builder, Trade.Type type, int quantity) {
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this.builder = builder;
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trade.setType( type );
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trade.setQuantity( quantity );
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}
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public StockBuilder stock(String symbol) {
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return new StockBuilder( builder, trade, symbol );
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}
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}
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public static class TradeBuilderWithStock {
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private final MethodChainingOrderBuilder builder;
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private final Trade trade;
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public TradeBuilderWithStock( MethodChainingOrderBuilder builder, Trade trade ) {
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this.builder = builder;
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this.trade = trade;
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}
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public MethodChainingOrderBuilder at(double price) {
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trade.setPrice( price );
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return builder.addTrade( trade );
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}
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}
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public static class StockBuilder {
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private final MethodChainingOrderBuilder builder;
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private final Trade trade;
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private final Stock stock = new Stock();
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private StockBuilder(MethodChainingOrderBuilder builder, Trade trade, String symbol) {
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this.builder = builder;
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this.trade = trade;
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stock.setSymbol( symbol );
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}
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public TradeBuilderWithStock on(String market) {
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stock.setMarket( market );
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trade.setStock( stock );
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return new TradeBuilderWithStock( builder, trade );
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}
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}
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}

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