Add CheckedSupplier to replace CheckedException

2bllw8 · Feb 21, 2022 · 7201261 · 7201261
1 parent 8fb6509
commit 7201261
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Showing 8 changed files with 83 additions and 45 deletions.
diff --git a/README.md b/README.md
@@ -34,9 +34,7 @@ implementation 'io.github.2bllw8:either:3.1.0'
 ## Usage
 
 ```java
-import exe.bbllw8.either.CheckedException;
 import exe.bbllw8.either.Try;
-import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Paths;
 import java.util.Arrays;
@@ -45,14 +43,10 @@ import java.util.stream.Collectors;
 public class Main {
 
     public static void main(String[] args) {
-        Arrays.stream(args).map((String arg) -> Try.from(() -> {
-                            try {
-                                return Files.lines(Paths.get(arg))
-                                        .collect(Collectors.joining("\n"));
-                            } catch (IOException e) {
-                                throw new CheckedException(e);
-                            }
-                        }).filter(text -> text.length() > 2)
+        Arrays.stream(args).map((String arg) -> Try.from(() ->
+                                Files.lines(Paths.get(arg))
+                                        .collect(Collectors.joining("\n")))
+                        .filter(text -> text.length() > 2)
                         .map(text -> text.substring(2))
                         .flatMap(text -> Try.from(() -> Integer.parseInt(text)))
                         .toEither()

diff --git a/lib/src/main/java/exe/bbllw8/either/CheckedException.java b/lib/src/main/java/exe/bbllw8/either/CheckedException.java
@@ -4,11 +4,9 @@
  */
 package exe.bbllw8.either;
 
-import java.util.function.Supplier;
-
 /**
  * A CheckedException instance is used to <i>catch</i> checked Exceptions for usage in {@link
- * Try#from(Supplier)}.
+ * Try#from(CheckedSupplier)}.
  *
  * <pre>
  * public class Example {
@@ -25,9 +23,11 @@
  * </pre>
  *
  * @author 2bllw8
- * @see Try#from(Supplier)
+ * @see Try#from(CheckedSupplier)
  * @since 2.2.0
+ * @deprecated Use {@link CheckedSupplier} instead of thowing wrapped exceptions.
  */
+@Deprecated
 public final class CheckedException extends RuntimeException {
 
     private static final long serialVersionUID = 2896775411630760282L;

diff --git a/lib/src/main/java/exe/bbllw8/either/CheckedSupplier.java b/lib/src/main/java/exe/bbllw8/either/CheckedSupplier.java
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2022 2bllw8
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package exe.bbllw8.either;
+
+/**
+ * Represents a supplier of results that may throw a {@link Throwable}.
+ *
+ * @param <T> The type of result supplied by this supplier
+ * @author 2bllw8
+ * @since 3.2.0
+ */
+@FunctionalInterface
+public interface CheckedSupplier<T> {
+
+    T get() throws Throwable;
+}
diff --git a/lib/src/main/java/exe/bbllw8/either/Failure.java b/lib/src/main/java/exe/bbllw8/either/Failure.java
@@ -21,6 +21,7 @@ public final class Failure<T> extends Try<T> {
     private transient final Throwable throwable;
 
     public Failure(Throwable throwable) {
+        assertNotFatal(throwable);
         this.throwable = throwable;
     }
 
@@ -140,4 +141,17 @@ public int hashCode() {
     public String toString() {
         return "Failure(" + throwable + ')';
     }
+
+    /**
+     * Assert that the given throwable is not fatal.
+     */
+    private static void assertNotFatal(Throwable t) {
+        if (t instanceof VirtualMachineError) {
+            throw (VirtualMachineError) t;
+        } else if (t instanceof ThreadDeath) {
+            throw (ThreadDeath) t;
+        } else if (t instanceof LinkageError) {
+            throw (LinkageError) t;
+        }
+    }
 }
diff --git a/lib/src/main/java/exe/bbllw8/either/Try.java b/lib/src/main/java/exe/bbllw8/either/Try.java
@@ -7,7 +7,6 @@
 import java.util.Optional;
 import java.util.function.Consumer;
 import java.util.function.Function;
-import java.util.function.Supplier;
 
 /**
  * The {@link Try} type represents a computation that may either result in an exception, or return a
@@ -40,7 +39,7 @@ public abstract class Try<T> {
      * <ul>
      *     <li>{@link Success}</li>
      *     <li>{@link Failure}</li>
-     *     <li>{@link Try#from(Supplier)}</li>
+     *     <li>{@link Try#from(CheckedSupplier)}</li>
      * </ul>
      *
      * @hidden
@@ -205,36 +204,19 @@ public static <T> Try<T> flatten(Try<Try<T>> tryTry) {
      *
      * @since 3.0.0
      */
-    @SuppressWarnings({"PMD.AvoidCatchingThrowable"})
-    public static <T> Try<T> from(Supplier<T> supplier) {
+    @SuppressWarnings({
+            "deprecation",
+            "PMD.AvoidCatchingThrowable",
+    })
+    public static <T> Try<T> from(CheckedSupplier<T> supplier) {
+        //noinspection deprecation
         try {
             return new Success<>(supplier.get());
-        } catch (CheckedException e) {
-            // Wrapped checked exception
-            final Throwable t = e.getCause();
-            if (isFatal(t)) {
-                // Fatal
-                throw e;
-            } else {
-                return new Failure<>(t);
-            }
+        } catch (CheckedException t) {
+            // TODO: remove this clause when CheckedException is removed
+            return new Failure<>(t.getCause());
         } catch (Throwable t) {
-            if (isFatal(t)) {
-                // Fatal
-                throw t;
-            } else {
-                return new Failure<>(t);
-            }
+            return new Failure<>(t);
         }
     }
-
-    /**
-     * @return Returns whether the given throwable is fatal.
-     */
-    private static boolean isFatal(Throwable t) {
-        return t instanceof VirtualMachineError
-                || t instanceof ThreadDeath
-                || t instanceof InterruptedException
-                || t instanceof LinkageError;
-    }
 }
diff --git a/lib/src/test/java/exe/bbllw8/either/FailureTest.java b/lib/src/test/java/exe/bbllw8/either/FailureTest.java
@@ -187,4 +187,34 @@ public void stringRepresentation() {
                     throw new IllegalStateException("something");
                 }).toString());
     }
+
+    @Test
+    public void multipleThrow() {
+        Assert.assertTrue("Multiple thrown classes are handled (throwable #1)",
+                Try.from(() -> new IntToBoolean().convert(2))
+                        .recover(t -> t instanceof IllegalAccessException)
+                        .get());
+        Assert.assertTrue("Multiple thrown classes are handled (throwable #2)",
+                Try.from(() -> new IntToBoolean().convert(3))
+                        .recover(t -> t instanceof IllegalArgumentException)
+                        .get());
+    }
+
+    private static class IntToBoolean {
+
+        boolean convert(int result) throws IllegalAccessException, IllegalArgumentException {
+            switch (result) {
+                case 0:
+                    return false;
+                case 1:
+                    return true;
+                case 2:
+                    // You have no authority to discover the dark truth about
+                    // the third hidden boolean value
+                    throw new IllegalAccessException();
+                default:
+                    throw new IllegalArgumentException();
+            }
+        }
+    }
 }
diff --git a/lib/src/test/java/exe/bbllw8/either/SuccessTest.java b/lib/src/test/java/exe/bbllw8/either/SuccessTest.java
@@ -108,7 +108,7 @@ public void transform() {
                 new Success<>(12),
                 Try.from(() -> "12").transform(value -> Try.from(() -> Integer.parseInt(value)),
                         t -> Try.from(() -> {
-                            throw new CheckedException(t);
+                            throw t;
                         })));
     }
 

diff --git a/lib/src/test/java/exe/bbllw8/either/TryTest.java b/lib/src/test/java/exe/bbllw8/either/TryTest.java
@@ -28,7 +28,7 @@ public void flatten() {
     public void from() {
         Assert.assertTrue("A supplier throwing an exception should return a failure",
                 Try.from(() -> {
-                    throw new CheckedException(new Throwable());
+                    throw new Throwable();
                 }).isFailure());
         Assert.assertTrue("A supplier throwing an exception should return a failure",
                 Try.from(() -> Integer.parseInt("-")).isFailure());