From 6bce6cf6490ce819f048b7ea8f1458ec66fbf1c8 Mon Sep 17 00:00:00 2001
From: "Harry T. Vennik" <htvennik@gmail.com>
Date: Thu, 20 Jul 2017 16:55:20 +0200
Subject: [PATCH] Added support for POD structs

Note: structs are deliberately considered last, because other stuff may
be implemented as structs as well. So we need to take care of special
cases before trying struct (de)serialization.
---
 source/ddbus/conv.d | 35 +++++++++++++++++++++++++++++++++++
 source/ddbus/util.d | 22 +++++++++++++++++-----
 2 files changed, 52 insertions(+), 5 deletions(-)

diff --git a/source/ddbus/conv.d b/source/ddbus/conv.d
index a8d4c19..d4a74cd 100644
--- a/source/ddbus/conv.d
+++ b/source/ddbus/conv.d
@@ -113,6 +113,11 @@ void buildIter(TS...)(DBusMessageIter *iter, TS args) if(allCanDBus!TS) {
       dbus_message_iter_open_container(iter, 'v', subSig, &sub);
       buildIter(&sub, arg.data);
       dbus_message_iter_close_container(iter, &sub);
+    } else static if(is(T == struct)) {
+      DBusMessageIter sub;
+      dbus_message_iter_open_container(iter, 'r', null, &sub);
+      buildIter(&sub, arg.tupleof);
+      dbus_message_iter_close_container(iter, &sub);
     } else static if(basicDBus!T) {
       dbus_message_iter_append_basic(iter,typeCode!T,&arg);
     }
@@ -265,6 +270,10 @@ T readIter(T)(DBusMessageIter *iter) if (!is(T == enum) && !isInstanceOf!(BitFla
       ret.entry.key = readIter!DBusAny(&sub);
       ret.entry.value = readIter!DBusAny(&sub);
     }
+  } else static if(is(T == struct)) {
+    DBusMessageIter sub;
+    dbus_message_iter_recurse(iter, &sub);
+    readIterStruct!T(&sub, ret);
   } else static if(basicDBus!T) {
     dbus_message_iter_get_basic(iter, &ret);
   }
@@ -279,6 +288,13 @@ void readIterTuple(Tup)(DBusMessageIter *iter, ref Tup tuple) if(isTuple!Tup &&
   }
 }
 
+void readIterStruct(S)(DBusMessageIter *iter, ref S s) if(is(S == struct) && allCanDBus!(Fields!S)) {
+  alias FieldNameTuple!S names;
+  foreach(index, T; Fields!S) {
+    __traits(getMember, s, names[index]) = readIter!T(iter);
+  }
+}
+
 unittest {
   import dunit.toolkit;
   import ddbus.thin;
@@ -355,3 +371,22 @@ unittest {
   readIter!F(&iter).assertThrow!InvalidValueException();
   readIter!(BitFlags!F)(&iter2).assertThrow!InvalidValueException();
 }
+
+unittest {
+  import dunit.toolkit;
+  import ddbus.thin;
+
+  struct S1 { int a; double b; string s; }
+  struct S2 { Variant!int c; string d; S1 e; uint f; }
+
+  Message msg = Message("org.example.wow", "/wut", "org.test.iface", "meth3");
+
+  enum testStruct = S2(variant(5), "blah", S1(-7, 63.5, "test"), 16);
+  msg.build(testStruct);
+
+  DBusMessageIter iter;
+  dbus_message_iter_init(msg.msg, &iter);
+
+  readIter!S2(&iter).assertEqual(testStruct);
+}
+
diff --git a/source/ddbus/util.d b/source/ddbus/util.d
index 968e89a..960624d 100644
--- a/source/ddbus/util.d
+++ b/source/ddbus/util.d
@@ -72,6 +72,8 @@ template canDBus(T) {
     }
   } else static if(isAssociativeArray!T) {
     enum canDBus = basicDBus!(KeyType!T) && canDBus!(ValueType!T);
+  } else static if(is(T == struct) && !isInstanceOf!(DictionaryEntry, T)) {
+    enum canDBus = allCanDBus!(Fields!T);
   } else {
     enum canDBus = false;
   }
@@ -130,6 +132,13 @@ string typeSig(T)() if(canDBus!T) {
     return "a" ~ typeSig!(ElementType!T)();
   } else static if(isAssociativeArray!T) {
     return "a{" ~ typeSig!(KeyType!T) ~ typeSig!(ValueType!T) ~ "}";
+  } else static if(is(T == struct)) {
+    string sig = "(";
+    foreach(i, S; Fields!T) {
+      sig ~= typeSig!S();
+    }
+    sig ~= ")";
+    return sig;
   }
 }
 
@@ -163,10 +172,8 @@ string[] typeSigArr(TS...)() if(allCanDBus!TS) {
 }
 
 int typeCode(T)() if(canDBus!T) {
-  static if (isTuple!T)
-    return 'r';
-  else
-    return typeSig!T()[0];
+  int code = typeSig!T()[0];
+  return (code != '(') ? code : 'r';
 }
 
 int typeCode(T)() if(isInstanceOf!(DictionaryEntry, T) && canDBus!(T[])) {
@@ -188,9 +195,14 @@ unittest {
   // bit flags
   enum F : uint { a = 1, b = 2, c = 4 }
   typeSig!(BitFlags!F)().assertEqual(typeSig!uint());
-  // structs
+  // tuples (represented as structs in DBus)
   typeSig!(Tuple!(int,string,string)).assertEqual("(iss)");
   typeSig!(Tuple!(int,string,Variant!int,Tuple!(int,"k",double,"x"))).assertEqual("(isv(id))");
+  // structs
+  struct S1 { int a; double b; string s; }
+  typeSig!S1.assertEqual("(ids)");
+  struct S2 { Variant!int c; string d; S1 e; uint f; }
+  typeSig!S2.assertEqual("(vs(ids)u)");
   // arrays
   typeSig!(int[]).assertEqual("ai");
   typeSig!(Variant!int[]).assertEqual("av");