Add actual mods.toml metadata parsing

src/main/java/dev/architectury/loom/metadata/ArchitecturyCommonJson.java

@@ -19,7 +19,7 @@ import org.jetbrains.annotations.Nullable;
 import net.fabricmc.loom.LoomGradlePlugin;
 import net.fabricmc.loom.configuration.ifaceinject.InterfaceInjectionProcessor;
 
-public final class ArchitecturyCommonJson implements JsonBackedModMetadataFile {
+public final class ArchitecturyCommonJson implements JsonBackedModMetadataFile, SingleIdModMetadataFile {
 	public static final String FILE_NAME = "architectury.common.json";
 	private static final String ACCESS_WIDENER_KEY = "accessWidener";
 

src/main/java/dev/architectury/loom/metadata/ModMetadataFile.java

@@ -6,6 +6,7 @@ import java.util.Set;
 import org.jetbrains.annotations.Nullable;
 
 import net.fabricmc.loom.configuration.ifaceinject.InterfaceInjectionProcessor;
+import net.fabricmc.loom.util.function.CollectionUtil;
 
 /**
  * The metadata file of a mod, such as {@link ArchitecturyCommonJson architectury.common.json} or
@@ -14,11 +15,17 @@ import net.fabricmc.loom.configuration.ifaceinject.InterfaceInjectionProcessor;
  * @see net.fabricmc.loom.util.fmj.FabricModJson
  */
 public interface ModMetadataFile {
+	/**
+	 * {@return all mod IDs in this mod metadata file}.
+	 */
+	Set<String> getIds();
+
 	/**
 	 * {@return the mod ID in this mod metadata file, or {@code null} if absent}.
 	 */
-	// TODO: When we have mods.toml here, shouldn't it support multiple IDs + maybe a "first ID"?
-	@Nullable String getId();
+	default @Nullable String getId() {
+		return CollectionUtil.first(getIds()).orElse(null);
+	}
 
 	/**
 	 * {@return the paths to the access widener file of this mod, or an empty set if absent}.

src/main/java/dev/architectury/loom/metadata/ModMetadataFiles.java

@@ -21,7 +21,7 @@ public final class ModMetadataFiles {
 	private static final Map<String, Function<byte[], ModMetadataFile>> SINGLE_FILE_METADATA_TYPES = ImmutableMap.<String, Function<byte[], ModMetadataFile>>builder()
 			.put(ArchitecturyCommonJson.FILE_NAME, ArchitecturyCommonJson::of)
 			.put(QuiltModJson.FILE_NAME, QuiltModJson::of)
-			.put(ModsToml.FILE_PATH, bytes -> ModsToml.INSTANCE)
+			.put(ModsToml.FILE_PATH, ModsToml::of)
 			.build();
 
 	/**

src/main/java/dev/architectury/loom/metadata/ModsToml.java

@@ -1,23 +1,69 @@
 package dev.architectury.loom.metadata;
 
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
 import java.util.List;
+import java.util.Objects;
+import java.util.Optional;
 import java.util.Set;
 
+import com.electronwill.nightconfig.core.Config;
+import com.electronwill.nightconfig.core.io.ParsingException;
+import com.electronwill.nightconfig.toml.TomlParser;
+import com.google.common.collect.ImmutableSet;
 import org.jetbrains.annotations.Nullable;
 
 import net.fabricmc.loom.configuration.ifaceinject.InterfaceInjectionProcessor;
 
-// A no-op mod metadata file for Forge's mods.toml.
 public final class ModsToml implements ModMetadataFile {
 	public static final String FILE_PATH = "META-INF/mods.toml";
-	public static final ModsToml INSTANCE = new ModsToml();
+	private final Config config;
 
-	private ModsToml() {
+	private ModsToml(Config config) {
+		this.config = Objects.requireNonNull(config);
+	}
+
+	public static ModsToml of(byte[] utf8) {
+		return of(new String(utf8, StandardCharsets.UTF_8));
+	}
+
+	public static ModsToml of(String text) {
+		try {
+			return new ModsToml(new TomlParser().parse(text));
+		} catch (ParsingException e) {
+			throw new IllegalArgumentException("Could not parse mods.toml", e);
+		}
+	}
+
+	public static ModsToml of(Path path) throws IOException {
+		try (BufferedReader reader = Files.newBufferedReader(path, StandardCharsets.UTF_8)) {
+			return new ModsToml(new TomlParser().parse(reader));
+		} catch (ParsingException e) {
+			throw new IllegalArgumentException("Could not parse mods.toml", e);
+		}
+	}
+
+	public static ModsToml of(File file) throws IOException {
+		return of(file.toPath());
 	}
 
 	@Override
-	public @Nullable String getId() {
-		return null;
+	public Set<String> getIds() {
+		final Optional<List<Config>> mods = config.getOptional("mods");
+		if (mods.isEmpty()) return Set.of();
+
+		final ImmutableSet.Builder<String> modIds = ImmutableSet.builder();
+
+		for (final Config mod : mods.get()) {
+			final Optional<String> modId = mod.getOptional("modId");
+			modId.ifPresent(modIds::add);
+		}
+
+		return modIds.build();
 	}
 
 	@Override
@@ -39,4 +85,14 @@ public final class ModsToml implements ModMetadataFile {
 	public List<String> getMixinConfigs() {
 		return List.of();
 	}
+
+	@Override
+	public boolean equals(Object obj) {
+		return obj == this || obj instanceof ModsToml modsToml && modsToml.config.equals(config);
+	}
+
+	@Override
+	public int hashCode() {
+		return config.hashCode();
+	}
 }

src/main/java/dev/architectury/loom/metadata/QuiltModJson.java

@@ -22,7 +22,7 @@ import net.fabricmc.loom.LoomGradlePlugin;
 import net.fabricmc.loom.configuration.ifaceinject.InterfaceInjectionProcessor;
 import net.fabricmc.loom.util.function.CollectionUtil;
 
-public final class QuiltModJson implements JsonBackedModMetadataFile {
+public final class QuiltModJson implements JsonBackedModMetadataFile, SingleIdModMetadataFile {
 	public static final String FILE_NAME = "quilt.mod.json";
 	private static final Logger LOGGER = LoggerFactory.getLogger(QuiltModJson.class);
 	private static final String ACCESS_WIDENER_KEY = "access_widener";

src/main/java/dev/architectury/loom/metadata/SingleIdModMetadataFile.java

@@ -0,0 +1,16 @@
+package dev.architectury.loom.metadata;
+
+import org.jetbrains.annotations.Nullable;
+
+import java.util.Set;
+
+interface SingleIdModMetadataFile extends ModMetadataFile {
+	@Override
+	default Set<String> getIds() {
+		final String id = getId();
+		return id != null ? Set.of(id) : Set.of();
+	}
+
+	@Override
+	@Nullable String getId();
+}

src/main/java/net/fabricmc/loom/util/function/CollectionUtil.java

@@ -144,4 +144,22 @@ public final class CollectionUtil {
 
 		return Optional.of(single);
 	}
+
+	/**
+	 * Gets the first element of an iterable.
+	 *
+	 * @param iterable the iterable
+	 * @param <A> the element type
+	 * @return the first element, or empty if there are no elements
+	 */
+	public static <A> Optional<A> first(Iterable<? extends A> iterable) {
+		final Iterator<? extends A> iter = iterable.iterator();
+
+		// No elements
+		if (!iter.hasNext()) {
+			return Optional.empty();
+		}
+
+		return Optional.of(iter.next());
+	}
 }