Change functions in enumerations and bitfields into instance methods …

…(when applicable)

buildSrc/src/main/java/io/github/jwharm/javagi/generators/CallableGenerator.java

@@ -133,9 +133,16 @@ PartialStatement marshalParameters() {
         PartialStatement stmt = PartialStatement.of(null,
                 "memorySegment", MemorySegment.class);
 
-        if (parameters.instanceParameter() != null)
-            stmt.add("handle()");
+        // Marshal instance parameter
+        InstanceParameter iParam = parameters.instanceParameter();
+        if (iParam != null) {
+            if (iParam.type().get() instanceof FlaggedType)
+                stmt.add("getValue()"); // method in Enumeration class
+            else
+                stmt.add("handle()");   // method in regular TypeInstance class
+        }
 
+        // Marshal other parameters
         for (Parameter p : parameters.parameters()) {
             if (!stmt.format().isEmpty()) stmt.add(", ");
             stmt.add("$Z"); // emit newline
@@ -146,7 +153,7 @@ PartialStatement marshalParameters() {
             if (generator.checkNull())
                 stmt.add("($memorySegment:T) (" + generator.getName() + " == null ? $memorySegment:T.NULL : ");
 
-            // callback destroy
+            // Callback destroy
             if (p.isDestroyNotifyParameter()) {
                 var notify = parameters.parameters().stream()
                         .filter(q -> q.destroy() == p)
@@ -159,7 +166,7 @@ PartialStatement marshalParameters() {
                 }
             }
 
-            // user_data
+            // User_data
             else if (p.isUserDataParameter())
                 stmt.add("$memorySegment:T.NULL");
 

buildSrc/src/main/java/io/github/jwharm/javagi/patches/BasePatch.java

@@ -1,9 +1,14 @@
 package io.github.jwharm.javagi.patches;
 
-import io.github.jwharm.javagi.gir.GirElement;
+import io.github.jwharm.javagi.gir.*;
 import io.github.jwharm.javagi.gir.Record;
 import io.github.jwharm.javagi.util.Patch;
 
+import java.util.ArrayList;
+import java.util.List;
+
+import static io.github.jwharm.javagi.util.CollectionUtils.listOfNonNull;
+
 /**
  * This patch will apply to all GIR files
  */
@@ -21,6 +26,52 @@ public GirElement patch(GirElement element, String namespace) {
                 && rec.name().endsWith("Private"))
             return element.withAttribute("java-gi-skip", "1");
 
+        /*
+         * Enumerations and Bitfields (flagged types) cannot have methods in
+         * GObject-Introspection, but this is allowed in Java. We change all
+         * functions where the first parameter is of the enclosing flagged type
+         * into methods with an instance parameter.
+         */
+        if (element instanceof FlaggedType t
+                && t.children().stream().anyMatch(Function.class::isInstance)) {
+
+            // Create a new list of nodes for the enumeration/bitfield,
+            // replacing functions by methods when possible.
+            List<Node> children = new ArrayList<>();
+            for (Node child : t.children()) {
+                if (child instanceof Function func
+                        && func.parameters() != null
+                        && func.parameters().parameters().getFirst().anyType() instanceof Type type
+                        && t.name().equals(type.name())) {
+
+                    // Create new <parameters> element for method
+                    var pList = func.parameters().parameters();
+                    var pFirst = pList.getFirst();
+                    var pOthers = pList.subList(1, pList.size());
+                    var pInstance = new InstanceParameter(pFirst.attributes(), pFirst.children());
+                    ArrayList<Node> paramList = new ArrayList<>(pOthers);
+                    paramList.addFirst(pInstance);
+
+                    // Construct <method> element
+                    Method method = new Method(
+                            func.attributes(),
+                            listOfNonNull(
+                                    func.infoElements().doc(),
+                                    func.infoElements().sourcePosition(),
+                                    func.returnValue(),
+                                    new Parameters(paramList)),
+                            func.platforms());
+
+                    // Add method to enumeration
+                    children.add(method);
+                } else {
+                    // Add node unmodified to enumeration
+                    children.add(child);
+                }
+            }
+            return t.withChildren(children);
+        }
+
         return element;
     }
 }

buildSrc/src/main/java/io/github/jwharm/javagi/util/CollectionUtils.java

@@ -22,6 +22,8 @@
 import io.github.jwharm.javagi.gir.Multiplatform;
 
 import java.util.*;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 /**
  * Utility functions for working with collections.
@@ -78,4 +80,17 @@ public static <A, B> Map<A, B> union(Map<A, B> map1, Map<A, B> map2) {
         map3.putAll(map2);
         return map3;
     }
+
+    /**
+     * Similar to {@link List#of}, but ignores {@code null} arguments.
+     */
+    @SafeVarargs
+    public static <T> List<T> listOfNonNull(T... elements) {
+        if (elements == null)
+            return Collections.emptyList();
+
+        return Stream.of(elements)
+                .filter(Objects::nonNull)
+                .collect(Collectors.toList());
+    }
 }