Generate ABI compatible structures for unions

Source/generator/ClassBase.cs

@@ -90,6 +90,9 @@ namespace GtkSharp.Generation {
 						abi_field = new StructABIField (member, this);
 						abi_fields.Add (abi_field);
 					}
+				} else if (node.Name == "union") {
+					abi_field = new UnionABIField (member, this);
+					abi_fields.Add (abi_field);
 				}
 
 				if (member.GetAttributeAsBoolean ("hidden"))

Source/generator/DESIGN

@@ -109,6 +109,7 @@ PropertyBase: Abstract base class for property-like elements
         ObjectField: Handles <field> elements in objects
         StructField: Handles <field> elements in structs
             StructABIField: Handles <fields> to generate ABI compatible structures
+                UnionABIField: Handles <union> to generate ABI compatible structures
             ClassField: Handles <field> elements in classes
     Property: Handles <property> elements
         ChildProperty: Handles <childprop> elements

Source/generator/UnionABIField.cs

@@ -0,0 +1,96 @@
+namespace GtkSharp.Generation {
+
+	using System;
+	using System.Collections;
+	using System.IO;
+	using System.Xml;
+	using System.Collections.Generic;
+
+	public class UnionSubstruct {
+		List<StructABIField> fields;
+		XmlElement Elem;
+		bool is_valid;
+		bool unique_field;
+
+		public UnionSubstruct(XmlElement elem, ClassBase container_type) {
+			fields = new List<StructABIField> ();
+			Elem = elem;
+			is_valid = true;
+			unique_field = false;
+
+			if (Elem.Name == "struct") {
+				foreach (XmlElement child_field in elem.ChildNodes) {
+					if (child_field.Name != "field") {
+						is_valid = false;
+						continue;
+					}
+
+					fields.Add(new StructABIField (child_field, container_type));
+				}
+			} else if (Elem.Name == "field") {
+				fields.Add(new StructABIField (Elem, container_type));
+				unique_field = true;
+			}
+		}
+
+		public void Generate(GenerationInfo gen_info, string indent){
+			StreamWriter sw = gen_info.Writer;
+			var name = Elem.GetAttribute("name");
+			var cname = Elem.GetAttribute("cname");
+
+			if (unique_field) {
+				sw.WriteLine (indent + "[FieldOffset(0)]");
+				foreach (StructABIField field in fields)
+					field.Generate(gen_info, indent);
+
+				return;
+			}
+
+			sw.WriteLine (indent + "struct __" + name + "{");
+			foreach (StructABIField field in fields) {
+				field.Generate(gen_info, indent + "\t");
+			}
+			sw.WriteLine (indent + "}");
+			sw.WriteLine (indent + "[FieldOffset(0)]");
+			sw.WriteLine (indent + "private __" + name + " " + cname + ";");
+		}
+	}
+
+	public class UnionABIField : StructABIField {
+		bool is_valid;
+		XmlElement Elem;
+		protected List<UnionSubstruct> substructs = new List<UnionSubstruct> ();
+
+
+		public UnionABIField (XmlElement elem, ClassBase container_type) : base (elem, container_type) {
+			Elem = elem;
+			is_valid = true;
+			foreach (XmlElement union_child in elem.ChildNodes) {
+				substructs.Add(new UnionSubstruct(union_child, container_type));
+			}
+		}
+
+		public override void Generate (GenerationInfo gen_info, string indent) {
+			StreamWriter sw = gen_info.Writer;
+			var name = Elem.GetAttribute("name");
+			var cname = Elem.GetAttribute("cname");
+
+			sw.WriteLine (indent + "[StructLayout(LayoutKind.Explicit)]");
+			sw.WriteLine (indent + "struct __" + name + " {");
+			foreach (UnionSubstruct _struct in substructs) {
+				_struct.Generate(gen_info, indent + "\t");
+			}
+			sw.WriteLine (indent + "}");
+			sw.WriteLine (indent + "private __" + name + " " + cname + ";");
+		}
+
+		public override bool Validate (LogWriter log)
+		{
+
+			if (!is_valid) {
+				log.Warn("Can't generate ABI compatible union");
+			}
+			return is_valid;
+		}
+	}
+}

Source/generator/meson.build

@@ -62,6 +62,7 @@ gapi_codegen = executable('gapi_codegen',
     'StructField.cs',
     'StructGen.cs',
     'SymbolTable.cs',
+    'UnionABIField.cs',
     'UnionGen.cs',
     'VirtualMethod.cs',
     'VMSignature.cs',