Add serialization of sources to flatbuffers

3 files changed, 173 insertions, 1 deletions

diff --git a/flatbuffers/sources.fbs b/flatbuffers/sources.fbs
index 9253bf6f..3b797d71 100644
--- a/flatbuffers/sources.fbs
+++ b/flatbuffers/sources.fbs
@@ -1,11 +1,15 @@
 namespace Sources;
 
-union Source {
+union SourceValue {
   NullSource,
   RuntimeSource,
   FileFragmentSource,
 }
 
+table Source {
+    value:SourceValue (required);
+}
+
 table NullSource {
 }
 
diff --git a/src/main/java/org/shedlang/compiler/sources/serialization/SourceToFlatbuffers.java b/src/main/java/org/shedlang/compiler/sources/serialization/SourceToFlatbuffers.java
new file mode 100644
index 00000000..7c1bb074
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/sources/serialization/SourceToFlatbuffers.java
@@ -0,0 +1,141 @@
+package org.shedlang.compiler.sources.serialization;
+
+import com.google.flatbuffers.FlatBufferBuilder;
+import org.shedlang.compiler.sources.*;
+import org.shedlang.compiler.sources.flatbuffers.*;
+import org.zwobble.sourcetext.SourcePosition;
+import org.zwobble.sourcetext.SourceRange;
+import org.zwobble.sourcetext.SourceText;
+
+import java.util.Optional;
+
+public class SourceToFlatbuffers {
+    private SourceToFlatbuffers() {
+    }
+
+    public static int serializeSource(
+        FlatBufferBuilder builder,
+        Source source,
+        Source parentSource
+    ) {
+        return serializeSource(builder, source, Optional.of(parentSource));
+    }
+
+    public static int serializeSource(
+        FlatBufferBuilder builder,
+        Source source,
+        Optional<Source> parentSource
+    ) {
+        switch (source) {
+            case NullSource nullSource -> {
+                NullSourceFbs.startNullSourceFbs(builder);
+                var nullSourceFbs = NullSourceFbs.endNullSourceFbs(builder);
+
+                SourceFbs.startSourceFbs(builder);
+                SourceFbs.addValueType(builder, SourceValueFbs.NullSourceFbs);
+                SourceFbs.addValue(builder, nullSourceFbs);
+                return SourceFbs.endSourceFbs(builder);
+            }
+            case RuntimeSource runtimeSource -> {
+                RuntimeSourceFbs.startRuntimeSourceFbs(builder);
+                var runtimeSourceFbs = RuntimeSourceFbs.endRuntimeSourceFbs(builder);
+
+                SourceFbs.startSourceFbs(builder);
+                SourceFbs.addValueType(builder, SourceValueFbs.RuntimeSourceFbs);
+                SourceFbs.addValue(builder, runtimeSourceFbs);
+                return SourceFbs.endSourceFbs(builder);
+            }
+            case FileFragmentSource fileFragmentSource -> {
+                var fileFragmentSourceFbs = serializeFileFragmentSource(builder, fileFragmentSource, parentSource);
+
+                SourceFbs.startSourceFbs(builder);
+                SourceFbs.addValueType(builder, SourceValueFbs.FileFragmentSourceFbs);
+                SourceFbs.addValue(
+                    builder,
+                    fileFragmentSourceFbs
+                );
+                return SourceFbs.endSourceFbs(builder);
+            }
+            default -> {
+                throw new UnsupportedOperationException("Unhandled source: " + source);
+            }
+        }
+    }
+
+    public static Source deserializeSource(
+        SourceFbs sourceFbs,
+        Source parentSource
+    ) {
+        return deserializeSource(sourceFbs, Optional.of(parentSource));
+    }
+
+    public static Source deserializeSource(
+        SourceFbs sourceFbs,
+        Optional<Source> parentSource
+    ) {
+        return switch (sourceFbs.valueType()) {
+            case SourceValueFbs.NullSourceFbs ->
+                Sources.NULL;
+
+            case SourceValueFbs.RuntimeSourceFbs ->
+                Sources.RUNTIME;
+
+            case SourceValueFbs.FileFragmentSourceFbs ->
+                deserializeFileFragmentSource(
+                    (FileFragmentSourceFbs) sourceFbs.value(new FileFragmentSourceFbs()),
+                    parentSource
+                );
+
+            default -> {
+                throw new UnsupportedOperationException("TODO");
+            }
+        };
+    }
+
+    private static int serializeFileFragmentSource(
+        FlatBufferBuilder builder,
+        FileFragmentSource source,
+        Optional<Source> parentSource
+    ) {
+        var sourceTextName = source.sourceRange().sourceText().name();
+        if (!(
+            parentSource.isPresent() &&
+                parentSource.get() instanceof FileFragmentSource(
+                    SourceRange parentSourceRange) &&
+                parentSourceRange.sourceText().name().equals(sourceTextName)
+        )) {
+            var sourceTextNameFbs = builder.createString(sourceTextName);
+            var sourceTextContentsFbs = builder.createString(source.sourceRange().sourceText().charSequence());
+            var sourceTextFbs = SourceTextFbs.createSourceTextFbs(builder, sourceTextNameFbs, sourceTextContentsFbs);
+            FileFragmentSourceFbs.startFileFragmentSourceFbs(builder);
+            FileFragmentSourceFbs.addSourceText(builder, sourceTextFbs);
+        } else {
+            FileFragmentSourceFbs.startFileFragmentSourceFbs(builder);
+        }
+
+        FileFragmentSourceFbs.addStartCharacterIndex(builder, source.sourceRange().start().characterIndex());
+        FileFragmentSourceFbs.addEndCharacterIndex(builder, source.sourceRange().end().characterIndex());
+
+        return FileFragmentSourceFbs.endFileFragmentSourceFbs(builder);
+    }
+
+    private static FileFragmentSource deserializeFileFragmentSource(
+        FileFragmentSourceFbs sourceFbs,
+        Optional<Source> parentSource
+    ) {
+        SourceText sourceText;
+        if (sourceFbs.sourceText() != null) {
+            sourceText = SourceText.fromString(
+                sourceFbs.sourceText().name(),
+                sourceFbs.sourceText().contents()
+            );
+        } else {
+            // TODO: handle missing parent
+            sourceText = ((FileFragmentSource) parentSource.orElseThrow()).sourceRange().sourceText();
+        }
+
+        var start = new SourcePosition(sourceText, (int) sourceFbs.startCharacterIndex());
+        var end = new SourcePosition(sourceText, (int) sourceFbs.endCharacterIndex());
+        return new FileFragmentSource(new SourceRange(sourceText, start, end));
+    }
+}
diff --git a/src/test/java/org/shedlang/compiler/sources/serialization/SourceToFlatbuffersTests.java b/src/test/java/org/shedlang/compiler/sources/serialization/SourceToFlatbuffersTests.java
new file mode 100644
index 00000000..31d20149
--- /dev/null
+++ b/src/test/java/org/shedlang/compiler/sources/serialization/SourceToFlatbuffersTests.java
@@ -0,0 +1,27 @@
+package org.shedlang.compiler.sources.serialization;
+
+import com.google.flatbuffers.FlatBufferBuilder;
+import com.google.protobuf.InvalidProtocolBufferException;
+import org.shedlang.compiler.sources.SourceSerializationTests;
+import org.shedlang.compiler.sources.flatbuffers.SourceFbs;
+import org.shedlang.compiler.sources.protobuf.SourcesProtobuf;
+
+import java.nio.ByteBuffer;
+
+public class SourceToFlatbuffersTests extends SourceSerializationTests {
+    public SourceToFlatbuffersTests() {
+        super(
+            (source, parentSource) -> {
+                var builder = new FlatBufferBuilder();
+                var sourceFbs = SourceToFlatbuffers.serializeSource(builder, source, parentSource);
+                builder.finish(sourceFbs);
+                return builder.sizedByteArray();
+            },
+
+            (serializedSource, parentSource) -> {
+                var sourceFbs = SourceFbs.getRootAsSourceFbs(ByteBuffer.wrap(serializedSource));
+                return SourceToFlatbuffers.deserializeSource(sourceFbs, parentSource);
+            }
+        );
+    }
+}