From e560f6bc63f2c51e48e4670910cb7c62698d115d Mon Sep 17 00:00:00 2001
From: Max Kellermann <max@musicpd.org>
Date: Sun, 3 Jun 2018 20:06:37 +0200
Subject: [PATCH] lib/dbus/ReadIter: add ForEachProperty()

---
 src/lib/dbus/ReadIter.hxx                     | 22 ++++++++++
 src/neighbor/plugins/UdisksNeighborPlugin.cxx | 42 +++++--------------
 2 files changed, 33 insertions(+), 31 deletions(-)

diff --git a/src/lib/dbus/ReadIter.hxx b/src/lib/dbus/ReadIter.hxx
index 60312a33c..a8ea9d7d4 100644
--- a/src/lib/dbus/ReadIter.hxx
+++ b/src/lib/dbus/ReadIter.hxx
@@ -102,6 +102,28 @@ public:
 				f(i.Recurse());
 			});
 	}
+
+	/**
+	 * Invoke a function for each name/value pair (string/variant)
+	 * in a dictionary (array containing #DBUS_TYPE_DICT_ENTRY).
+	 * The function gets two parameters: the property name (as C
+	 * string) and the variant value (as #ReadMessageIter).
+	 */
+	template<typename F>
+	void ForEachProperty(F &&f) {
+		ForEachRecurse(DBUS_TYPE_DICT_ENTRY, [&f](auto &&i){
+				if (i.GetArgType() != DBUS_TYPE_STRING)
+					return;
+
+				const char *name = i.GetString();
+				i.Next();
+
+				if (i.GetArgType() != DBUS_TYPE_VARIANT)
+					return;
+
+				f(name, i.Recurse());
+			});
+	}
 };
 
 } /* namespace ODBus */
diff --git a/src/neighbor/plugins/UdisksNeighborPlugin.cxx b/src/neighbor/plugins/UdisksNeighborPlugin.cxx
index 7bd0a0351..1e14bea44 100644
--- a/src/neighbor/plugins/UdisksNeighborPlugin.cxx
+++ b/src/neighbor/plugins/UdisksNeighborPlugin.cxx
@@ -202,44 +202,23 @@ CheckString(I &&i) noexcept
 	return i.GetString();
 }
 
-template<typename I>
-gcc_pure
-static const char *
-CheckVariantString(I &&i) noexcept
-{
-	if (i.GetArgType() != DBUS_TYPE_VARIANT)
-		return nullptr;
-
-	return CheckString(i.Recurse());
-}
-
 static void
-ParseDriveDictEntry(UdisksObject &o, ODBus::ReadMessageIter &&i) noexcept
+ParseDriveDictEntry(UdisksObject &o, const char *name,
+		    ODBus::ReadMessageIter &&value_i) noexcept
 {
-	if (i.GetArgType() != DBUS_TYPE_STRING)
-		return;
-
-	const char *name = i.GetString();
-	i.Next();
-
 	if (StringIsEqual(name, "Id")) {
-		const char *value = CheckVariantString(i);
+		const char *value = CheckString(value_i);
 		if (value != nullptr && o.drive_id.empty())
 			o.drive_id = value;
 	}
 }
 
 static void
-ParseBlockDictEntry(UdisksObject &o, ODBus::ReadMessageIter &&i) noexcept
+ParseBlockDictEntry(UdisksObject &o, const char *name,
+		    ODBus::ReadMessageIter &&value_i) noexcept
 {
-	if (i.GetArgType() != DBUS_TYPE_STRING)
-		return;
-
-	const char *name = i.GetString();
-	i.Next();
-
 	if (StringIsEqual(name, "Id")) {
-		const char *value = CheckVariantString(i);
+		const char *value = CheckString(value_i);
 		if (value != nullptr && o.block_id.empty())
 			o.block_id = value;
 	}
@@ -249,12 +228,13 @@ static void
 ParseInterface(UdisksObject &o, const char *interface,
 	       ODBus::ReadMessageIter &&i) noexcept
 {
+	using namespace std::placeholders;
 	if (StringIsEqual(interface, "org.freedesktop.UDisks2.Drive")) {
-		for (; i.GetArgType() == DBUS_TYPE_DICT_ENTRY; i.Next())
-			ParseDriveDictEntry(o, i.Recurse());
+		i.ForEachProperty(std::bind(ParseDriveDictEntry,
+					    std::ref(o), _1, _2));
 	} else if (StringIsEqual(interface, "org.freedesktop.UDisks2.Block")) {
-		for (; i.GetArgType() == DBUS_TYPE_DICT_ENTRY; i.Next())
-			ParseBlockDictEntry(o, i.Recurse());
+		i.ForEachProperty(std::bind(ParseBlockDictEntry,
+					    std::ref(o), _1, _2));
 	} else if (StringIsEqual(interface, "org.freedesktop.UDisks2.Filesystem")) {
 		o.is_filesystem = true;
 	}