Add fallbackToRawInputWhenEmpty configuration

CHANGELOG.md

@@ -10,10 +10,12 @@
 * Update `jlatexmath-android` dependency ([#225])
 * Update `image-coil` module (Coil version `0.10.1`) ([#244])<br>Thanks to [@tylerbwong]
 * Rename `UrlProcessor` to `ImageDestinationProcessor` (`io.noties.markwon.urlprocessor` -&gt; `io.noties.markwon.image.destination`) and limit its usage to process **only** destination URL of images (was used to also process links before)
+* `fallbackToRawInputWhenEmpty` `Markwon.Builder` configuration to fallback to raw input if rendered markdown is empty ([#242]) 
 
 [#235]: https://github.com/noties/Markwon/issues/235
 [#225]: https://github.com/noties/Markwon/issues/225
 [#244]: https://github.com/noties/Markwon/pull/244
+[#242]: https://github.com/noties/Markwon/issues/242
 [@tylerbwong]: https://github.com/tylerbwong
 
 

markwon-core/src/main/java/io/noties/markwon/Markwon.java

@@ -192,6 +192,17 @@ public abstract class Markwon {
         @NonNull
         Builder usePlugins(@NonNull Iterable<? extends MarkwonPlugin> plugins);
 
+        /**
+         * Control if small chunks of non-finished markdown sentences (for example, a single `*` character)
+         * should be displayed/rendered as raw input instead of an empty string.
+         * <p>
+         * Since $nap; {@code true} by default, versions prior - {@code false}
+         *
+         * @since $nap;
+         */
+        @NonNull
+        Builder fallbackToRawInputWhenEmpty(boolean fallbackToRawInputWhenEmpty);
+
         @NonNull
         Markwon build();
     }

markwon-core/src/main/java/io/noties/markwon/MarkwonBuilderImpl.java

@@ -27,6 +27,9 @@ class MarkwonBuilderImpl implements Markwon.Builder {
 
     private Markwon.TextSetter textSetter;
 
+    // @since $nap;
+    private boolean fallbackToRawInputWhenEmpty = true;
+
     MarkwonBuilderImpl(@NonNull Context context) {
         this.context = context;
     }
@@ -71,6 +74,13 @@ class MarkwonBuilderImpl implements Markwon.Builder {
         return this;
     }
 
+    @NonNull
+    @Override
+    public Markwon.Builder fallbackToRawInputWhenEmpty(boolean fallbackToRawInputWhenEmpty) {
+        this.fallbackToRawInputWhenEmpty = fallbackToRawInputWhenEmpty;
+        return this;
+    }
+
     @NonNull
     @Override
     public Markwon build() {
@@ -114,7 +124,8 @@ class MarkwonBuilderImpl implements Markwon.Builder {
                 parserBuilder.build(),
                 visitorFactory,
                 configuration,
-                Collections.unmodifiableList(plugins)
+                Collections.unmodifiableList(plugins),
+                fallbackToRawInputWhenEmpty
         );
     }
 

markwon-core/src/main/java/io/noties/markwon/MarkwonImpl.java

@@ -1,6 +1,8 @@
 package io.noties.markwon;
 
+import android.text.SpannableStringBuilder;
 import android.text.Spanned;
+import android.text.TextUtils;
 import android.widget.TextView;
 
 import androidx.annotation.NonNull;
@@ -28,19 +30,25 @@ class MarkwonImpl extends Markwon {
     @Nullable
     private final TextSetter textSetter;
 
+    // @since $nap;
+    private final boolean fallbackToRawInputWhenEmpty;
+
     MarkwonImpl(
             @NonNull TextView.BufferType bufferType,
             @Nullable TextSetter textSetter,
             @NonNull Parser parser,
             @NonNull MarkwonVisitorFactory visitorFactory,
             @NonNull MarkwonConfiguration configuration,
-            @NonNull List<MarkwonPlugin> plugins) {
+            @NonNull List<MarkwonPlugin> plugins,
+            boolean fallbackToRawInputWhenEmpty
+    ) {
         this.bufferType = bufferType;
         this.textSetter = textSetter;
         this.parser = parser;
         this.visitorFactory = visitorFactory;
         this.configuration = configuration;
         this.plugins = plugins;
+        this.fallbackToRawInputWhenEmpty = fallbackToRawInputWhenEmpty;
     }
 
     @NonNull
@@ -86,7 +94,18 @@ class MarkwonImpl extends Markwon {
     @NonNull
     @Override
     public Spanned toMarkdown(@NonNull String input) {
-        return render(parse(input));
+        final Spanned spanned = render(parse(input));
+
+        // @since $nap;
+        // if spanned is empty, we are configured to use raw input and input is not empty
+        if (TextUtils.isEmpty(spanned)
+                && fallbackToRawInputWhenEmpty
+                && !TextUtils.isEmpty(input)) {
+            // let's use SpannableStringBuilder in order to keep backward-compatibility
+            return new SpannableStringBuilder(input);
+        }
+
+        return spanned;
     }
 
     @Override

markwon-core/src/test/java/io/noties/markwon/MarkwonImplTest.java

@@ -1,6 +1,7 @@
 package io.noties.markwon;
 
 import android.text.Spanned;
+import android.text.TextUtils;
 import android.widget.TextView;
 
 import org.commonmark.node.Node;
@@ -50,7 +51,9 @@ public class MarkwonImplTest {
                 mock(Parser.class),
                 mock(MarkwonVisitorFactory.class),
                 mock(MarkwonConfiguration.class),
-                Collections.singletonList(plugin));
+                Collections.singletonList(plugin),
+                true
+        );
 
         impl.parse("whatever");
 
@@ -74,7 +77,9 @@ public class MarkwonImplTest {
                 parser,
                 mock(MarkwonVisitorFactory.class),
                 mock(MarkwonConfiguration.class),
-                Arrays.asList(first, second));
+                Arrays.asList(first, second),
+                true
+        );
 
         impl.parse("zero");
 
@@ -102,7 +107,9 @@ public class MarkwonImplTest {
                 mock(Parser.class),
                 visitorFactory,
                 mock(MarkwonConfiguration.class),
-                Collections.singletonList(plugin));
+                Collections.singletonList(plugin),
+                true
+        );
 
         when(visitorFactory.create()).thenReturn(visitor);
         when(visitor.builder()).thenReturn(builder);
@@ -149,7 +156,9 @@ public class MarkwonImplTest {
                 mock(Parser.class),
                 visitorFactory,
                 mock(MarkwonConfiguration.class),
-                Collections.<MarkwonPlugin>emptyList());
+                Collections.<MarkwonPlugin>emptyList(),
+                true
+        );
 
         impl.render(mock(Node.class));
 
@@ -185,7 +194,9 @@ public class MarkwonImplTest {
                 mock(Parser.class),
                 visitorFactory,
                 mock(MarkwonConfiguration.class),
-                Collections.singletonList(plugin));
+                Collections.singletonList(plugin),
+                true
+        );
 
         final AtomicBoolean flag = new AtomicBoolean(false);
         final Node node = mock(Node.class);
@@ -224,7 +235,9 @@ public class MarkwonImplTest {
                 mock(Parser.class),
                 mock(MarkwonVisitorFactory.class, RETURNS_MOCKS),
                 mock(MarkwonConfiguration.class),
-                Collections.singletonList(plugin));
+                Collections.singletonList(plugin),
+                true
+        );
 
         final TextView textView = mock(TextView.class);
         final AtomicBoolean flag = new AtomicBoolean(false);
@@ -272,7 +285,9 @@ public class MarkwonImplTest {
                 mock(Parser.class),
                 mock(MarkwonVisitorFactory.class),
                 mock(MarkwonConfiguration.class),
-                plugins);
+                plugins,
+                true
+        );
 
         assertTrue("First", impl.hasPlugin(First.class));
         assertFalse("Second", impl.hasPlugin(Second.class));
@@ -295,7 +310,9 @@ public class MarkwonImplTest {
                 mock(Parser.class),
                 mock(MarkwonVisitorFactory.class),
                 mock(MarkwonConfiguration.class),
-                Collections.singletonList(plugin));
+                Collections.singletonList(plugin),
+                true
+        );
 
         final TextView textView = mock(TextView.class);
         final Spanned spanned = mock(Spanned.class);
@@ -339,7 +356,9 @@ public class MarkwonImplTest {
                 mock(Parser.class),
                 mock(MarkwonVisitorFactory.class),
                 mock(MarkwonConfiguration.class),
-                plugins);
+                plugins,
+                true
+        );
 
         // should be returned
         assertNotNull(impl.requirePlugin(MarkwonPlugin.class));
@@ -370,7 +389,9 @@ public class MarkwonImplTest {
                 mock(Parser.class),
                 mock(MarkwonVisitorFactory.class),
                 mock(MarkwonConfiguration.class),
-                plugins);
+                plugins,
+                true
+        );
 
         final List<? extends MarkwonPlugin> list = impl.getPlugins();
 
@@ -385,4 +406,42 @@ public class MarkwonImplTest {
             assertTrue(e.getMessage(), true);
         }
     }
+
+    @Test
+    public void fallback_to_raw() {
+        final String md = "*";
+
+        final MarkwonImpl impl = new MarkwonImpl(
+                TextView.BufferType.SPANNABLE,
+                null,
+                mock(Parser.class, RETURNS_MOCKS),
+                // it must be sufficient to just return mocks and thus empty rendering result
+                mock(MarkwonVisitorFactory.class, RETURNS_MOCKS),
+                mock(MarkwonConfiguration.class),
+                Collections.<MarkwonPlugin>emptyList(),
+                true
+        );
+
+        final Spanned spanned = impl.toMarkdown(md);
+        assertEquals(md, spanned.toString());
+    }
+
+    @Test
+    public void fallback_to_raw_false() {
+        final String md = "*";
+
+        final MarkwonImpl impl = new MarkwonImpl(
+                TextView.BufferType.SPANNABLE,
+                null,
+                mock(Parser.class, RETURNS_MOCKS),
+                // it must be sufficient to just return mocks and thus empty rendering result
+                mock(MarkwonVisitorFactory.class, RETURNS_MOCKS),
+                mock(MarkwonConfiguration.class),
+                Collections.<MarkwonPlugin>emptyList(),
+                false
+        );
+
+        final Spanned spanned = impl.toMarkdown(md);
+        assertTrue(spanned.toString(), TextUtils.isEmpty(spanned));
+    }
 }