Add Result.mapFailure (#34)

Signed-off-by: David Greven <[email protected]> Signed-off-by: Sebastian Becker <[email protected]>
carbynestack · Dec 13, 2021 · a73b4a5 · a73b4a5
1 parent 9da9521
commit a73b4a5
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Showing 9 changed files with 157 additions and 0 deletions.
diff --git a/common-testing/src/test/java/io/carbynestack/common/result/FailureTest.java b/common-testing/src/test/java/io/carbynestack/common/result/FailureTest.java
@@ -58,6 +58,17 @@ void mapAndTransformType() {
                 .hasReason(reason);
     }
 
+    @Test
+    void mapFailure() {
+        assertThat(result.mapFailure(r -> r * 2)).hasReason(reason * 2);
+    }
+
+    @Test
+    void mapFailureNullPointerException() {
+        assertThatThrownBy(() -> result.mapFailure(null))
+                .isExactlyInstanceOf(NullPointerException.class);
+    }
+
     @Test
     void tryMap() {
         assertThat(result.tryMap(v -> v * 2, reason * 2)).hasReason(reason);
@@ -69,6 +80,12 @@ void tryMapNullPointerException() {
                 .isExactlyInstanceOf(NullPointerException.class);
     }
 
+    @Test
+    void mapFailureAndTransformType() {
+        assertThat(result.mapFailure(r -> String.format("%s * 2 -> %s", r, r * 2)))
+                .hasReason("21 * 2 -> 42");
+    }
+
     @Test
     void tryMapAndTransformType() {
         assertThat(result.tryMap(v -> String.format("%s * 2 -> %s", v, v * 2),

diff --git a/common-testing/src/test/java/io/carbynestack/common/result/SuccessTest.java b/common-testing/src/test/java/io/carbynestack/common/result/SuccessTest.java
@@ -59,6 +59,17 @@ void mapAndTransformType() {
                 .hasValue("12 * 2 -> 24");
     }
 
+    @Test
+    void mapFailure() {
+        assertThat(result.mapFailure(r -> r * 2)).hasValue(value);
+    }
+
+    @Test
+    void mapFailureNullPointerException() {
+        assertThatThrownBy(() -> result.mapFailure(null))
+              .isExactlyInstanceOf(NullPointerException.class);
+    }
+
     @Test
     void tryMap() {
         assertThat(result.tryMap(v -> v * 2, -11)).hasValue(24);
@@ -70,6 +81,12 @@ void tryMapNullPointerException() {
                 .isExactlyInstanceOf(NullPointerException.class);
     }
 
+    @Test
+    void mapFailureAndTransformType() {
+        assertThat(result.mapFailure(r -> String.format("%s * 2 -> %s", r, r * 2)))
+                .hasValue(value);
+    }
+
     @Test
     void tryMapAndTransformType() {
         assertThat(result.tryMap(v -> String.format("%s * 2 -> %s", v, v * 2),

diff --git a/common-types/src/main/java/io/carbynestack/common/result/Failure.java b/common-types/src/main/java/io/carbynestack/common/result/Failure.java
@@ -90,6 +90,26 @@ public <N> Result<N, F> map(Function<? super S, ? super N> function) {
         return new Failure<>(this.reason());
     }
 
+    /**
+     * {@inheritDoc}
+     *
+     * @param function the mapping function to apply to a {@link Failure#reason()}
+     * @param <R>      the failure type of the value returned from the mapping
+     *                 function
+     * @return the {@code Result} of mapping the given function to the value
+     * from this {@link Failure} or this {@link Success}
+     * @throws NullPointerException if the mapping function is {@code null}
+     * @version JDK 8
+     * @see #map(Function)
+     * @see #recover(Function)
+     * @since 0.2.0
+     */
+    @Override
+    @SuppressWarnings("unchecked")
+    public <R> Result<S, R> mapFailure(Function<? super F, ? super R> function) {
+        return new Failure<>((R) function.apply(this.reason()));
+    }  
+
     /**
      * {@inheritDoc}
      *

diff --git a/common-types/src/main/java/io/carbynestack/common/result/Result.java b/common-types/src/main/java/io/carbynestack/common/result/Result.java
@@ -160,6 +160,23 @@ default boolean isFailure() {
      */
     <N> Result<N, F> map(Function<? super S, ? super N> function);
 
+    /**
+     * If the {@code Result} is a {@link Failure}, returns the result of
+     * applying the given mapping function to the {@link Failure#reason()}.
+     * Otherwise, a cast version of the {@link Success} is returned.
+     *
+     * @param function the mapping function to apply to a {@link Failure#reason()}
+     * @param <R>      the failure type of the value returned from the mapping
+     *                 function
+     * @return the {@code Result} of mapping the given function to the value
+     * from this {@link Failure} or this {@link Success}
+     * @throws NullPointerException if the mapping function is {@code null}
+     * @see #map(Function)
+     * @see #recover(Function)
+     * @since 0.2.0
+     */
+    <R> Result<S, R> mapFailure(Function<? super F, ? super R> function);
+
     /**
      * If the {@code Result} is a {@link Success}, returns the result of
      * applying the given mapping function to the {@link Success#value()}.

diff --git a/common-types/src/main/java/io/carbynestack/common/result/Success.java b/common-types/src/main/java/io/carbynestack/common/result/Success.java
@@ -91,6 +91,26 @@ public <N> Result<N, F> map(Function<? super S, ? super N> function) {
         return new Success<>((N) function.apply(this.value()));
     }
 
+    /**
+     * {@inheritDoc}
+     *
+     * @param function the mapping function to apply to a {@link Failure#reason()}
+     * @param <R>      the failure type of the value returned from the mapping
+     *                 function
+     * @return the {@code Result} of mapping the given function to the value
+     * from this {@link Failure} or this {@link Success}
+     * @throws NullPointerException if the mapping function is {@code null}
+     * @version JDK 8
+     * @see #map(Function)
+     * @see #recover(Function)
+     * @since 0.2.0
+     */
+    @Override
+    public <R> Result<S, R> mapFailure(Function<? super F, ? super R> function) {
+        requireNonNull(function);
+        return new Success<>(this.value());
+    }
+
     /**
      * {@inheritDoc}
      *

diff --git a/common-types/src/main/java17/io/carbynestack/common/result/Failure.java b/common-types/src/main/java17/io/carbynestack/common/result/Failure.java
@@ -61,6 +61,26 @@ public <N> Result<N, F> map(Function<? super S, ? super N> function) {
         return new Failure<>(this.reason());
     }
 
+    /**
+     * {@inheritDoc}
+     *
+     * @param function the mapping function to apply to a {@link Failure#reason()}
+     * @param <R>      the failure type of the value returned from the mapping
+     *                 function
+     * @return the {@code Result} of mapping the given function to the value
+     * from this {@link Failure} or this {@link Success}
+     * @throws NullPointerException if the mapping function is {@code null}
+     * @version JDK 17
+     * @see #map(Function)
+     * @see #recover(Function)
+     * @since 0.2.0
+     */
+    @Override
+    @SuppressWarnings("unchecked")
+    public <R> Result<S, R> mapFailure(Function<? super F, ? super R> function) {
+        return new Failure<>((R) function.apply(this.reason()));
+    }
+
     /**
      * {@inheritDoc}
      *

diff --git a/common-types/src/main/java17/io/carbynestack/common/result/Result.java b/common-types/src/main/java17/io/carbynestack/common/result/Result.java
@@ -160,6 +160,23 @@ default boolean isFailure() {
      */
     <N> Result<N, F> map(Function<? super S, ? super N> function);
 
+    /**
+     * If the {@code Result} is a {@link Failure}, returns the result of
+     * applying the given mapping function to the {@link Failure#reason()}.
+     * Otherwise, a cast version of the {@link Success} is returned.
+     *
+     * @param function the mapping function to apply to a {@link Failure#reason()}
+     * @param <R>      the failure type of the value returned from the mapping
+     *                 function
+     * @return the {@code Result} of mapping the given function to the value
+     * from this {@link Failure} or this {@link Success}
+     * @throws NullPointerException if the mapping function is {@code null}
+     * @see #map(Function)
+     * @see #recover(Function)
+     * @since 0.2.0
+     */
+    <R> Result<S, R> mapFailure(Function<? super F, ? super R> function);
+
     /**
      * If the {@code Result} is a {@link Success}, returns the result of
      * applying the given mapping function to the {@link Success#value()}.

diff --git a/common-types/src/main/java17/io/carbynestack/common/result/Success.java b/common-types/src/main/java17/io/carbynestack/common/result/Success.java
@@ -62,6 +62,26 @@ public <N> Result<N, F> map(Function<? super S, ? super N> function) {
         return new Success<>((N) function.apply(this.value()));
     }
 
+    /**
+     * {@inheritDoc}
+     *
+     * @param function the mapping function to apply to a {@link Failure#reason()}
+     * @param <R>      the failure type of the value returned from the mapping
+     *                 function
+     * @return the {@code Result} of mapping the given function to the value
+     * from this {@link Failure} or this {@link Success}
+     * @throws NullPointerException if the mapping function is {@code null}
+     * @version JDK 17
+     * @see #map(Function)
+     * @see #recover(Function)
+     * @since 0.2.0
+     */
+    @Override
+    public <R> Result<S, R> mapFailure(Function<? super F, ? super R> function) {
+        requireNonNull(function);
+        return new Success<>(this.value());
+    }
+
     /**
      * {@inheritDoc}
      *

diff --git a/common-types/src/test/java/io/carbynestack/common/result/ResultTest.java b/common-types/src/test/java/io/carbynestack/common/result/ResultTest.java
@@ -77,6 +77,15 @@ void result() {
         assertThat(res.stream().toList()).isEmpty();
     }
 
+    @Test
+    void mapFailure() {
+        assertThat(new Success<>(12)
+                .mapFailure(Long.TYPE::cast)
+                .flatMap(v -> new Failure<Integer, Long>((long) v * 2))
+                .mapFailure(Long::intValue)
+                .isFailure()).isTrue();
+    }
+
     @Test
     void tryPeek() {
         assertThat(new Success<>(12)