[mutter] monitor: Add hash function

[Marge Bot <marge-bot src gnome org>]

commit 4615da2122d9fcfa4bc87dee0994ec9213330486
Author: Jonas Ådahl <jadahl gmail com>
Date:   Fri Feb 5 17:21:55 2021 +0100

    monitor: Add hash function
    
    Will be used to keep a monitor spec as a hash table key.
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1712>

 src/backends/meta-monitor.c | 11 +++++++++++
 src/backends/meta-monitor.h |  2 ++
 2 files changed, 13 insertions(+)
---
diff --git a/src/backends/meta-monitor.c b/src/backends/meta-monitor.c
index 2d9ec50518..54a228e835 100644
--- a/src/backends/meta-monitor.c
+++ b/src/backends/meta-monitor.c
@@ -127,6 +127,17 @@ meta_monitor_spec_clone (MetaMonitorSpec *monitor_spec)
   return new_monitor_spec;
 }
 
+guint
+meta_monitor_spec_hash (gconstpointer key)
+{
+  const MetaMonitorSpec *monitor_spec = key;
+
+  return (g_str_hash (monitor_spec->connector) +
+          g_str_hash (monitor_spec->vendor) +
+          g_str_hash (monitor_spec->product) +
+          g_str_hash (monitor_spec->serial));
+}
+
 gboolean
 meta_monitor_spec_equals (MetaMonitorSpec *monitor_spec,
                           MetaMonitorSpec *other_monitor_spec)
diff --git a/src/backends/meta-monitor.h b/src/backends/meta-monitor.h
index c1b62806e2..4b3a527e30 100644
--- a/src/backends/meta-monitor.h
+++ b/src/backends/meta-monitor.h
@@ -262,6 +262,8 @@ gboolean meta_monitor_mode_should_be_advertised (MetaMonitorMode *monitor_mode);
 META_EXPORT_TEST
 MetaMonitorSpec * meta_monitor_spec_clone (MetaMonitorSpec *monitor_id);
 
+guint meta_monitor_spec_hash (gconstpointer key);
+
 META_EXPORT_TEST
 gboolean meta_monitor_spec_equals (MetaMonitorSpec *monitor_id,
                                    MetaMonitorSpec *other_monitor_id);