feat (core): GEXF!

docs/concepts/other.md

@@ -99,11 +99,11 @@ Enola 🕵🏾‍♀️ visualizes (TBD) the relationships of its _Entities_ usi
 * [yEd](https://www.yworks.com) (yFiles) #commercial #sdk #freemium
 * [Graphviz](https://graphviz.org) #available
 * [Gephi](https://gephi.org), with [Gephi Lite](https://gephi.org/gephi-lite/) which uses [SigmaJS](https://www.sigmajs.org) on [Graphology](https://graphology.github.io) for JS #[FOSDEM](https://github.com/vorburger/vorburger.ch-Notes/blob/develop/conferences/FOSDEM-2024.md) #dynamicGraph #web #active #planned #ToDo
-* [D3js.org](https://d3js.org) also has [Graphs](https://observablehq.com/@d3/force-directed-graph-component?collection=@d3/charts) (and [d3rdf](https://github.com/Rathachai/d3rdf))
-* [vis.js](https://visjs.org)
+* [D3js.org](https://d3js.org), and [Observable Plot](https://observablehq.com/plot/) has #[graph](https://observablehq.com/@d3/force-directed-graph-component?collection=@d3/charts) (and [d3rdf](https://github.com/Rathachai/d3rdf)) #[timeline](https://observablehq.com/@observablehq/plot-civilizations-timeline?intent=fork)
+* [vis.js](https://visjs.org) #opensource #graph #timeline #web
 * [Cytoscape](https://cytoscape.org) #opensource #graph #desktop #[plugins](https://apps.cytoscape.org/)
 * [Cytoscape.js](https://js.cytoscape.org/) #graph #library #web
-* [Mermaid](https://mermaid.js.org) #opensource
+* [Mermaid](https://mermaid.js.org) #graph #[timeline](https://mermaid.js.org/syntax/timeline.html) #opensource
 * [PlantUML](https://plantuml.com) #opensource
 * [GraphStream](https://graphstream-project.org) #opensource #dynamicGraph #java #swing #desktop #inactive
 * [Vega Lite](https://vega.github.io/vega-lite/) & [Vega](https://vega.github.io/vega/) #opensource

java/dev/enola/common/time/TimesTest.java

@@ -0,0 +1,41 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Copyright 2024 The Enola <https://enola.dev> Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package dev.enola.common.time;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import org.junit.Test;
+
+import java.time.Instant;
+import java.time.temporal.ChronoUnit;
+
+public class TimesTest {
+
+    @Test
+    public void beginningOfTimeInstantToString() {
+        var instant = Instant.MIN.plus(1, ChronoUnit.DAYS);
+        var text = "-1000000000-01-02T00:00:00Z";
+        assertThat(instant.toString()).isEqualTo(text);
+    }
+
+    @Test
+    public void endOfTimeWithInstantParse() {
+        // NB: The + prefix is mandatory if it's not 4 YYYY digits
+        Instant.parse("+300000-12-30T23:59:59Z");
+    }
+}

java/dev/enola/core/rosetta/Rosetta.java

@@ -36,6 +36,8 @@
 import dev.enola.core.meta.proto.EntityKinds;
 import dev.enola.core.proto.Entity;
 import dev.enola.rdf.RdfResourceConverter;
+import dev.enola.thing.gen.gexf.GexfGenerator;
+import dev.enola.thing.gen.gexf.GexfResourceConverter;
 import dev.enola.thing.gen.graphviz.GraphvizGenerator;
 import dev.enola.thing.gen.graphviz.GraphvizResourceConverter;
 import dev.enola.thing.metadata.ThingMetadataProvider;
@@ -94,6 +96,7 @@ public Rosetta(ResourceProvider rp) {
                                 messageResourceConverter,
                                 new YamlJsonResourceConverter(),
                                 new GraphvizResourceConverter(new GraphvizGenerator(tmp)),
+                                new GexfResourceConverter(new GexfGenerator(tmp)),
                                 new CharResourceConverter()));
     }
 

java/dev/enola/core/rosetta/RosettaTest.java

@@ -41,6 +41,7 @@
 import dev.enola.model.Datatypes;
 import dev.enola.rdf.RdfMediaTypes;
 import dev.enola.thing.Thing;
+import dev.enola.thing.gen.gexf.GexfMediaType;
 import dev.enola.thing.gen.graphviz.GraphvizMediaType;
 import dev.enola.thing.impl.ImmutableThing;
 import dev.enola.thing.io.ThingMediaTypes;
@@ -186,10 +187,8 @@ public void testYamlToTurtle() throws Exception {
     }
 
     @Test
-    public void testGraphviz() throws Exception {
-        var in = rp.get("classpath:/graphviz.ttl");
-        var out = new MemoryResource(GraphvizMediaType.GV);
-
+    public void testGraphvizAndGexf() throws Exception {
+        var in = rp.get("classpath:/graph.ttl");
         try (var ctx = TLC.open()) {
             // This tests that StackedThingProvider in GraphvizGenerator works;
             // if it did not "shadow", then we would have an empty Salutation.
@@ -203,10 +202,14 @@ public void testGraphviz() throws Exception {
             var namespaceConverter = new NamespaceConverterWithRepository(namespaceRepo);
             ctx.push(NamespaceConverter.class, namespaceConverter);
 
-            rosetta.convertInto(in, out);
-        }
+            var gexf = new MemoryResource(GexfMediaType.GEXF);
+            rosetta.convertInto(in, gexf);
+            assertThat(gexf)
+                    .hasCharsEqualTo(rp.get("classpath:/graph.expected.gexf.xml?charset=UTF-8"));
 
-        var expectedOut = rp.get("classpath:/graphviz.expected.gv");
-        assertThat(out).hasCharsEqualTo(expectedOut);
+            var gv = new MemoryResource(GraphvizMediaType.GV);
+            rosetta.convertInto(in, gv);
+            assertThat(gv).hasCharsEqualTo(rp.get("classpath:/graph.expected.gv"));
+        }
     }
 }

java/dev/enola/datatype/BUILD

@@ -25,6 +25,7 @@ java_library(
     ),
     visibility = ["//:__subpackages__"],
     deps = [
+        "//java/dev/enola/common",
         "//java/dev/enola/common/context",
         "//java/dev/enola/common/convert",
         "//java/dev/enola/data",

java/dev/enola/datatype/Datatype.java

@@ -56,4 +56,6 @@ default ObjectToStringBiConverter<Object> stringConverterFromObject() {
     Optional<Class<T>> javaType();
 
     // TODO Optional<TypeToken<T>> javaTypeToken();
+
+    DatatypeBuilder<T> child();
 }

java/dev/enola/datatype/DatatypeBuilder.java

@@ -0,0 +1,56 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Copyright 2024 The Enola <https://enola.dev> Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package dev.enola.datatype;
+
+import static java.util.Objects.requireNonNull;
+
+import dev.enola.common.Builder;
+import dev.enola.common.convert.ObjectToStringBiConverter;
+
+import org.jspecify.annotations.Nullable;
+
+import java.util.Optional;
+import java.util.regex.Pattern;
+
+public class DatatypeBuilder<T> implements Builder<Datatype<T>> {
+
+    private String iri;
+    private final @Nullable Pattern pattern;
+    private final ObjectToStringBiConverter<T> stringConverter;
+    private final @Nullable Class<T> javaType;
+
+    DatatypeBuilder(Datatype<T> clone) {
+        this.iri = clone.iri();
+        this.pattern = clone.pattern().orElse(null);
+        this.stringConverter = clone.stringConverter();
+        this.javaType = clone.javaType().orElse(null);
+    }
+
+    public DatatypeBuilder<T> iri(String iri) {
+        this.iri = requireNonNull(iri);
+        return this;
+    }
+
+    // TODO setters for (all?) other methods of Datatype
+
+    @Override
+    public Datatype<T> build() {
+        return new ImmutableDatatype<T>(
+                iri, Optional.ofNullable(pattern), stringConverter, Optional.ofNullable(javaType));
+    }
+}

java/dev/enola/datatype/ImmutableDatatype.java

@@ -62,4 +62,9 @@ public ImmutableDatatype(
             String pattern) {
         this(iri, stringConverter, javaType, Pattern.compile(pattern));
     }
+
+    @Override
+    public DatatypeBuilder<T> child() {
+        return new DatatypeBuilder<>(this);
+    }
 }

java/dev/enola/model/enola/Datatypes.java

@@ -25,12 +25,19 @@
 import dev.enola.datatype.ImmutableDatatype;
 
 import java.nio.file.attribute.FileTime;
+import java.time.Instant;
 
 /** Enola's built-in core datatypes. */
 // TODO Doc: <p>See https://enola.dev/datatypes --- once we put something on
 // https://docs.enola.dev/models/datatypes and have a working HTTP redirector.
 public final class Datatypes {
 
+    public static final Datatype<Instant> TIMESTAMP =
+            dev.enola.model.xsd.Datatypes.DATE_TIME
+                    .child()
+                    .iri("https://enola.dev/Timestamp")
+                    .build();
+
     public static final Datatype<UnsignedLong> UNSIGNED_LONG =
             new ImmutableDatatype<>(
                     "https://enola.dev/UnsignedLong",
@@ -50,7 +57,8 @@ public final class Datatypes {
     // Replace use of Base64.getEncoder().encodeToString() in MessageToThingConverter#b64()
 
     // Beware: The order here matters very much, for DatatypeRepository#match()
-    public static final Iterable<Datatype<?>> ALL = ImmutableList.of(UNSIGNED_LONG, FILE_TIME);
+    public static final Iterable<Datatype<?>> ALL =
+            ImmutableList.of(UNSIGNED_LONG, TIMESTAMP, FILE_TIME);
 
     private Datatypes() {}
 }

java/dev/enola/model/schemaorg/Datatypes.java

@@ -20,20 +20,14 @@
 import com.google.common.collect.ImmutableList;
 
 import dev.enola.datatype.Datatype;
-import dev.enola.datatype.ImmutableDatatype;
 
 import java.time.LocalDate;
 
 /** Datatypes for <a href="https://schema.org/">Schema.org</a>. */
 public final class Datatypes {
 
-    // TODO How-to copy/paste even less from dev.enola.model.xsd.Datatypes.DATE?
     public static final Datatype<LocalDate> DATE =
-            new ImmutableDatatype<>(
-                    "https://schema.org/Date",
-                    dev.enola.model.xsd.Datatypes.DATE.stringConverter(),
-                    LocalDate.class,
-                    dev.enola.model.xsd.Datatypes.DATE.pattern().get());
+            dev.enola.model.xsd.Datatypes.DATE.child().iri("https://schema.org/Date").build();
 
     // Beware: The order here may matter very much, for DatatypeRepository#match()
     public static final Iterable<Datatype<?>> ALL = ImmutableList.of(DATE);

java/dev/enola/thing/PredicatesObjects.java

@@ -55,6 +55,9 @@ public interface PredicatesObjects {
     // TODO Reconsider if this method is really required? Why not just #properties().keySet()?
     Set<String> predicateIRIs();
 
+    // TODO These is*() methods could be replaced with a Visitor - but how-to for nested Structs?!
+    // Look into e.g. how EMF does Visitors...
+
     default boolean isLink(String predicateIRI) {
         var value = get(predicateIRI);
         return value instanceof URI || value instanceof Link;

java/dev/enola/thing/gen/BUILD

@@ -34,6 +34,7 @@ java_library(
         "//java/dev/enola/common/convert",
         "//java/dev/enola/common/function",
         "//java/dev/enola/common/io",
+        "//java/dev/enola/common/time",
         "//java/dev/enola/common/tree",
         "//java/dev/enola/data",
         "//java/dev/enola/datatype",

java/dev/enola/thing/gen/ThingsIntoAppendableConverter.java

@@ -0,0 +1,40 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Copyright 2024 The Enola <https://enola.dev> Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package dev.enola.thing.gen;
+
+import dev.enola.common.convert.ConversionException;
+import dev.enola.common.convert.ConverterIntoAppendable;
+import dev.enola.common.io.metadata.Metadata;
+import dev.enola.common.io.resource.WritableResource;
+import dev.enola.thing.Thing;
+
+import java.io.IOException;
+
+public interface ThingsIntoAppendableConverter extends ConverterIntoAppendable<Iterable<Thing>> {
+
+    default void convertIntoOrThrow(Iterable<Thing> things, WritableResource into)
+            throws ConversionException, IOException {
+        try (var out = into.charSink().openBufferedStream()) {
+            convertIntoOrThrow(things, out);
+        }
+    }
+
+    default String label(Metadata metadata) {
+        return metadata.emoji() + metadata.label();
+    }
+}