From bc7ee2539bf270a700a7c9deaea82b9a53f4e659 Mon Sep 17 00:00:00 2001
From: Semyon Kirekov <semyon@kirekov.com>
Date: Tue, 3 Aug 2021 20:24:06 +0300
Subject: [PATCH] [#142] - Delete 'Lazy' monad

---
 src/main/java/com/kirekov/juu/monad/Lazy.java | 93 -------------------
 .../java/com/kirekov/juu/monad/LazyTest.java  | 73 ---------------
 2 files changed, 166 deletions(-)
 delete mode 100644 src/main/java/com/kirekov/juu/monad/Lazy.java
 delete mode 100644 src/test/java/com/kirekov/juu/monad/LazyTest.java

diff --git a/src/main/java/com/kirekov/juu/monad/Lazy.java b/src/main/java/com/kirekov/juu/monad/Lazy.java
deleted file mode 100644
index b01c8de..0000000
--- a/src/main/java/com/kirekov/juu/monad/Lazy.java
+++ /dev/null
@@ -1,93 +0,0 @@
-package com.kirekov.juu.monad;
-
-import com.kirekov.juu.collection.Streaming;
-import java.util.Objects;
-import java.util.function.Function;
-import java.util.function.Supplier;
-import java.util.stream.Stream;
-
-/**
- * Monad for lazy calculations. Allows to build a chain of operations with deferred execution.
- * Operations will NOT be executed until {@link Lazy#calculate()} method will be called.
- *
- * @param <T> the type of the return parameter
- * @since 1.0
- */
-public final class Lazy<T> implements Streaming<T> {
-
-  private final Supplier<T> supplier;
-
-  private Lazy(Supplier<T> supplier) {
-    this.supplier = supplier;
-  }
-
-  /**
-   * Instantiates new Lazy object.
-   *
-   * @param supplier supplier which will be called by {@link Lazy#calculate()} method
-   * @param <T>      the type of the return parameter
-   * @return lazy object
-   * @throws NullPointerException if supplier is null
-   */
-  public static <T> Lazy<T> of(Supplier<T> supplier) {
-    return new Lazy<>(Objects.requireNonNull(supplier));
-  }
-
-  /**
-   * Makes the chain with input parameter of previous execution. <br>
-   * <b>NB:</b> map does not trigger execution.
-   *
-   * @param mapper mapping function
-   * @param <U>    the return type
-   * @return lazy object
-   * @throws NullPointerException if mapper is null
-   */
-  public <U> Lazy<U> map(Function<? super T, ? extends U> mapper) {
-    Objects.requireNonNull(mapper);
-    return Lazy.of(() -> mapper.apply(supplier.get()));
-  }
-
-  /**
-   * Makes the chain with input parameter of previous execution.
-   * <br>
-   * <b>NB:</b> flatMap does not trigger the execution.
-   * <br>
-   * After triggering the execution flatMap returns not the lazy object, but the result of its inner
-   * calculation.
-   * <pre> {@code
-   * Lazy.of(() -> 1)
-   *     .flatMap(v -> Lazy.of(() -> v + 1))
-   *     .calculate()
-   * }</pre>
-   * returns 2
-   *
-   * @param mapper mapping function
-   * @param <U>    the return type
-   * @return lazy object
-   * @throws NullPointerException if mapper is null
-   */
-  public <U> Lazy<U> flatMap(Function<? super T, ? extends Lazy<? extends U>> mapper) {
-    Objects.requireNonNull(mapper);
-    return Lazy.of(() -> mapper.apply(supplier.get()).calculate());
-  }
-
-  /**
-   * Triggers calculation and returns the result.
-   *
-   * @return the result of calculation
-   */
-  public T calculate() {
-    return supplier.get();
-  }
-
-  /**
-   * Triggers calculation and returns the result as {@link Stream}.
-   *
-   * @return the stream of calculation result
-   * @see Lazy#calculate()
-   */
-  @Override
-  public Stream<T> stream() {
-    return Stream.of(calculate());
-  }
-}
diff --git a/src/test/java/com/kirekov/juu/monad/LazyTest.java b/src/test/java/com/kirekov/juu/monad/LazyTest.java
deleted file mode 100644
index dc64237..0000000
--- a/src/test/java/com/kirekov/juu/monad/LazyTest.java
+++ /dev/null
@@ -1,73 +0,0 @@
-package com.kirekov.juu.monad;
-
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertThrows;
-import static org.junit.jupiter.api.Assertions.assertTrue;
-import static org.mockito.Mockito.mock;
-import static org.mockito.Mockito.times;
-import static org.mockito.Mockito.verify;
-
-import java.util.Collection;
-import java.util.Optional;
-import org.junit.jupiter.api.Test;
-
-/**
- * Test cases for {@linkplain Lazy}.
- *
- * @see Lazy
- */
-class LazyTest {
-
-  @Test
-  void ofThrowsNullPointerExceptionIfSupplierIsNull() {
-    assertThrows(NullPointerException.class, () -> Lazy.of(null));
-  }
-
-  @Test
-  void testLazyReallyActsLazy() {
-    @SuppressWarnings("unchecked")
-    Collection<Integer> collection = (Collection<Integer>) mock(Collection.class);
-    Lazy<Integer> lazy =
-        Lazy.of(() -> {
-          int val = 1;
-          collection.add(val);
-          return val;
-        }).map(v -> {
-          int val = v + 1;
-          collection.add(val);
-          return val;
-        }).map(v -> {
-          int val = v + 1;
-          collection.add(val);
-          return val;
-        }).flatMap(v -> {
-          int val = v + 1;
-          collection.add(val);
-          return Lazy.of(() -> val);
-        });
-    verify(collection, times(0)).add(1);
-    verify(collection, times(0)).add(2);
-    verify(collection, times(0)).add(3);
-    verify(collection, times(0)).add(4);
-
-    int result = lazy.calculate();
-
-    assertEquals(4, result);
-    verify(collection, times(1)).add(1);
-    verify(collection, times(1)).add(2);
-    verify(collection, times(1)).add(3);
-    verify(collection, times(1)).add(4);
-  }
-
-  @Test
-  void testStream() {
-    Optional<String> opt =
-        Lazy.of(() -> "1")
-            .map(v -> v + "2")
-            .map(v -> v + "3")
-            .stream()
-            .findFirst();
-    assertTrue(opt.isPresent());
-    assertEquals("123", opt.get());
-  }
-}
\ No newline at end of file