Add Signature and Variant types.
Change-Id: I3579fb8745d7b021af7534d2f0c5a0aa6ce54518
diff --git a/src/main/java/eu/mulk/jgvariant/core/Signature.java b/src/main/java/eu/mulk/jgvariant/core/Signature.java
new file mode 100644
index 0000000..bb03b94
--- /dev/null
+++ b/src/main/java/eu/mulk/jgvariant/core/Signature.java
@@ -0,0 +1,113 @@
+package eu.mulk.jgvariant.core;
+
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+import java.text.ParseException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+
+/**
+ * A GVariant signature string.
+ *
+ * <p>Describes a type in the GVariant type system. The type can be arbitrarily complex.
+ *
+ * <p><strong>Examples</strong>
+ *
+ * <dl>
+ * <dt>{@code "i"}
+ * <dd>a single 32-bit integer
+ * <dt>{@code "ai"}
+ * <dd>an array of 32-bit integers
+ * <dt>{@code "(bbb(sai))"}
+ * <dd>a record consisting of three booleans and a nested record, which consists of a string and
+ * an array of 32-bit integers
+ * </dl>
+ */
+public final class Signature {
+
+ private final String signatureString;
+ private final Decoder<?> decoder;
+
+ Signature(ByteBuffer signatureBytes) throws ParseException {
+ this.decoder = parseSignature(signatureBytes);
+
+ signatureBytes.rewind();
+ this.signatureString = StandardCharsets.US_ASCII.decode(signatureBytes).toString();
+ }
+
+ static Signature parse(ByteBuffer signatureBytes) throws ParseException {
+ return new Signature(signatureBytes);
+ }
+
+ static Signature parse(String signatureString) throws ParseException {
+ var signatureBytes = ByteBuffer.wrap(signatureString.getBytes(StandardCharsets.US_ASCII));
+ return parse(signatureBytes);
+ }
+
+ /**
+ * Returns a {@link Decoder} that can decode values conforming to this signature.
+ *
+ * @return a {@link Decoder} for this signature
+ */
+ @SuppressWarnings("unchecked")
+ Decoder<Object> decoder() {
+ return (Decoder<Object>) decoder;
+ }
+
+ /**
+ * Returns the signature formatted as a GVariant signature string.
+ *
+ * @return a GVariant signature string.
+ */
+ @Override
+ public String toString() {
+ return signatureString;
+ }
+
+ @Override
+ public boolean equals(Object o) {
+ return (o instanceof Signature signature)
+ && Objects.equals(signatureString, signature.signatureString);
+ }
+
+ @Override
+ public int hashCode() {
+ return Objects.hash(signatureString);
+ }
+
+ private static Decoder<?> parseSignature(ByteBuffer signature) throws ParseException {
+ char c = (char) signature.get();
+ return switch (c) {
+ case 'b' -> Decoder.ofBoolean();
+ case 'y' -> Decoder.ofByte();
+ case 'n', 'q' -> Decoder.ofShort();
+ case 'i', 'u' -> Decoder.ofInt();
+ case 'x', 't' -> Decoder.ofLong();
+ case 'd' -> Decoder.ofDouble();
+ case 's', 'o', 'g' -> Decoder.ofString(StandardCharsets.UTF_8);
+ case 'v' -> Decoder.ofVariant();
+ case 'm' -> Decoder.ofMaybe(parseSignature(signature));
+ case 'a' -> Decoder.ofArray(parseSignature(signature));
+ case '(', '{' -> Decoder.ofStructure(parseTupleTypes(signature).toArray(new Decoder<?>[0]));
+ default -> throw new ParseException(
+ String.format("encountered unknown signature byte '%c'", c), signature.position());
+ };
+ }
+
+ private static List<Decoder<?>> parseTupleTypes(ByteBuffer signature) throws ParseException {
+ List<Decoder<?>> decoders = new ArrayList<>();
+
+ while (true) {
+ char c = (char) signature.get(signature.position());
+ if (c == ')' || c == '}') {
+ signature.get();
+ break;
+ }
+
+ decoders.add(parseSignature(signature));
+ }
+
+ return decoders;
+ }
+}