Begin on graph universe

Author: Kneelawk

modules/core-xplat/src/main/java/com/kneelawk/graphlib/v3/api/GraphLib.java

@@ -1,8 +1,50 @@
 package com.kneelawk.graphlib.v3.api;
 
+import java.util.NoSuchElementException;
+
+import org.jetbrains.annotations.Nullable;
+
+import net.minecraft.resources.ResourceLocation;
+
+import com.kneelawk.graphlib.v3.api.graph.GraphUniverse;
+import com.kneelawk.graphlib.v3.impl.GraphLibImpl;
+
 /**
  * GraphLib Public API.
  */
 public final class GraphLib {
     private GraphLib() {}
+
+    /**
+     * Gets whether the given universe has been registered.
+     *
+     * @param universeId the id of the universe to check.
+     * @return {@code true} if the universe has been registered.
+     */
+    public static boolean universeExists(ResourceLocation universeId) {
+        return GraphLibImpl.UNIVERSES.containsKey(universeId);
+    }
+
+    /**
+     * Gets the graph universe registered with the given id if any.
+     *
+     * @param universeId the id of the graph universe to lookup.
+     * @return the graph universe with the given id or {@code null} if none could be found.
+     */
+    public static @Nullable GraphUniverse getUniverse(ResourceLocation universeId) {
+        return GraphLibImpl.UNIVERSES.get(universeId);
+    }
+
+    /**
+     * Gets the graph universe given with the given id or throws.
+     *
+     * @param universeId the id of the graph universe to lookup.
+     * @return the graph universe with the given id.
+     * @throws NoSuchElementException if no graph universe could be found with the given id.
+     */
+    public static GraphUniverse getUniverseOrThrow(ResourceLocation universeId) {
+        GraphUniverse universe = getUniverse(universeId);
+        if (universe == null) throw new NoSuchElementException("No universe exists with the name " + universeId);
+        return universe;
+    }
 }

modules/core-xplat/src/main/java/com/kneelawk/graphlib/v3/api/graph/GraphUniverse.java

@@ -0,0 +1,41 @@
+package com.kneelawk.graphlib.v3.api.graph;
+
+import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.NotNull;
+
+import com.mojang.serialization.Codec;
+import com.mojang.serialization.DataResult;
+
+import net.minecraft.resources.ResourceLocation;
+
+import com.kneelawk.codextra.api.attach.AttachmentKey;
+import com.kneelawk.graphlib.v3.api.GraphLib;
+
+/**
+ * Manages all graphs and graph accessories.
+ */
+@ApiStatus.NonExtendable
+public interface GraphUniverse {
+
+    /**
+     * Graph-Universe attachment key for use in codecs.
+     */
+    AttachmentKey<GraphUniverse> ATTACHMENT_KEY = AttachmentKey.ofStaticFieldName();
+
+    /**
+     * Codec for referencing a graph universe.
+     */
+    Codec<GraphUniverse> REF_CODEC = ResourceLocation.CODEC.comapFlatMap(id -> {
+        if (!GraphLib.universeExists(id))
+            return DataResult.error(() -> "The graph universe '" + id + "' does not exist");
+        return DataResult.success(GraphLib.getUniverseOrThrow(id));
+    }, GraphUniverse::getId);
+
+    /**
+     * Gets the unique id of this universe.
+     *
+     * @return this universe's unique id.
+     */
+    @NotNull
+    ResourceLocation getId();
+}

modules/core-xplat/src/main/java/com/kneelawk/graphlib/v3/api/graph/package-info.java

@@ -0,0 +1,12 @@
+/**
+ * GraphLib interface.
+ */
+@ParametersAreNonnullByDefault
+@MethodsReturnNonnullByDefault
+@FieldsAreNonnullByDefault
+package com.kneelawk.graphlib.v3.api.graph;
+
+import javax.annotation.ParametersAreNonnullByDefault;
+
+import net.minecraft.FieldsAreNonnullByDefault;
+import net.minecraft.MethodsReturnNonnullByDefault;

modules/core-xplat/src/main/java/com/kneelawk/graphlib/v3/api/util/InUniverse.java

@@ -0,0 +1,48 @@
+package com.kneelawk.graphlib.v3.api.util;
+
+import com.mojang.serialization.Codec;
+import com.mojang.serialization.MapCodec;
+import com.mojang.serialization.codecs.RecordCodecBuilder;
+
+import com.kneelawk.graphlib.v3.api.graph.GraphUniverse;
+
+/**
+ * Describes an object in a {@link GraphUniverse}.
+ *
+ * @param universe the universe the object is within.
+ * @param obj      the object.
+ * @param <T>      the type of the object.
+ */
+public record InUniverse<T>(GraphUniverse universe, T obj) {
+    /**
+     * Creates an in-universe map codec for the given type.
+     * <p>
+     * <b>This provides the {@link GraphUniverse#ATTACHMENT_KEY} attachment.</b>
+     * <p>
+     * This uses the {@code universe} map key for the universe, but anything else can be used by the obj-codec.
+     *
+     * @param objCodec the codec for the object to be associated with a universe.
+     * @param <T>      the wrapped object type.
+     * @return the created map codec.
+     */
+    public static <T> MapCodec<InUniverse<T>> mapCodec(MapCodec<T> objCodec) {
+        return GraphUniverse.ATTACHMENT_KEY.keyAttachingCodec(GraphUniverse.REF_CODEC.fieldOf("universe"),
+            RecordCodecBuilder.mapCodec(instance -> instance.group(
+                GraphUniverse.ATTACHMENT_KEY.retrieve(),
+                objCodec.forGetter(InUniverse::obj)
+            ).apply(instance, InUniverse::new)), InUniverse::universe);
+    }
+
+    /**
+     * Codecs-only version of {@link #mapCodec(MapCodec)}.
+     * <p>
+     * <b>This provides the {@link GraphUniverse#ATTACHMENT_KEY} attachment.</b>
+     *
+     * @param objCodec the codec for the object to be associated with a universe.
+     * @param <T>      the wrapped object type.
+     * @return the created codec.
+     */
+    public static <T> Codec<InUniverse<T>> codec(Codec<T> objCodec) {
+        return mapCodec(objCodec.fieldOf("value")).codec();
+    }
+}

modules/core-xplat/src/main/java/com/kneelawk/graphlib/v3/impl/GraphLibImpl.java

@@ -0,0 +1,13 @@
+package com.kneelawk.graphlib.v3.impl;
+
+import java.util.Map;
+
+import it.unimi.dsi.fastutil.objects.Object2ObjectLinkedOpenHashMap;
+
+import net.minecraft.resources.ResourceLocation;
+
+import com.kneelawk.graphlib.v3.api.graph.GraphUniverse;
+
+public class GraphLibImpl {
+    public static final Map<ResourceLocation, GraphUniverse> UNIVERSES = new Object2ObjectLinkedOpenHashMap<>();
+}