[libgweather] Adding support of filter function to find_nearest_city method

[Giovanni Campagna <gcampagna src gnome org>]

commit 7bc341bb17b230a579cf51a84fbc7c5998caf141
Author: Saurabh_P <srp201201051 gmail com>
Date:   Thu Mar 13 02:39:21 2014 +0530

    Adding support of filter function to find_nearest_city method
    
    Add new api named find_nearest_city_full similar to find_nearest_city
    and take new argumnets to take filter function from the app and the filter
    function return true to continue checking for the location and
    returns false to filter it out.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=726186

 libgweather/gweather-location.c |   78 +++++++++++++++++++++++++++++++++++---
 libgweather/gweather-location.h |    8 ++++
 2 files changed, 79 insertions(+), 7 deletions(-)
---
diff --git a/libgweather/gweather-location.c b/libgweather/gweather-location.c
index 5d12982..5fc5f2e 100644
--- a/libgweather/gweather-location.c
+++ b/libgweather/gweather-location.c
@@ -519,16 +519,23 @@ gweather_location_get_children (GWeatherLocation *loc)
 }
 
 static void
-foreach_cities (GWeatherLocation *loc,
-               GFunc             callback,
-               gpointer          user_data)
+foreach_city (GWeatherLocation  *loc,
+              GFunc              callback,
+              gpointer           user_data,
+              GWeatherFilterFunc func,
+              gpointer           user_data_func)
 {
-    if (loc->level == GWEATHER_LOCATION_CITY) {
-       callback (loc, user_data);
+    if (func) {
+        if (!func (loc, user_data_func))
+            return;
+    }
+
+    if (loc->level == GWEATHER_LOCATION_WEATHER_STATION) {
+        callback (loc, user_data);
     } else if (loc->children) {
         int i;
         for (i = 0; loc->children[i]; i++)
-            foreach_cities (loc->children[i], callback, user_data);
+            foreach_city (loc->children[i], callback, user_data, func, user_data_func);
     }
 }
 
@@ -607,7 +614,64 @@ gweather_location_find_nearest_city (GWeatherLocation *loc,
     data.location = NULL;
     data.distance = 0.0;
 
-    foreach_cities (loc, (GFunc) find_nearest_city, &data);
+    foreach_city (loc, (GFunc) find_nearest_city, &data, NULL, NULL);
+
+    return gweather_location_ref (data.location);
+}
+
+/**
+ * gweather_location_find_nearest_city_full:
+ * @loc: (allow-none): The parent location, which will be searched recursively
+ * @lat: Latitude, in degrees
+ * @lon: Longitude, in degrees
+ * @func: (scope notified) (allow-none): returns true to continue check for
+ *                                       the location and false to filter the location out
+ * @user_data: for customization
+ * @destroy: to destroy user_data
+ *
+ * Finds the nearest city to the passed latitude and
+ * longitude, among the descendants of @loc.
+ *
+ * Supports the use of own filter function to filter out locations.
+ * Geocoding should be done on the application side if needed.
+ *
+ * @loc must be at most a %GWEATHER_LOCATION_LEVEL_ADM2 location.
+ * This restriction may be lifted in a future version.
+ *
+ * Returns: (transfer full): the city closest to (@lat, @lon), in the
+ *          region or administrative district of @loc with validation of filter function.
+ *
+ * Since: 3.12
+ */
+GWeatherLocation *
+gweather_location_find_nearest_city_full (GWeatherLocation  *loc,
+                                         double             lat,
+                                         double             lon,
+                                         GWeatherFilterFunc func,
+                                         gpointer           user_data,
+                                         GDestroyNotify     destroy)
+{
+   /* The data set really isn't too big. Don't concern ourselves
+     * with a proper nearest neighbors search. Instead, just do
+     * an O(n) search. */
+    struct FindNearestCityData data;
+
+    g_return_val_if_fail (loc == NULL || loc->level < GWEATHER_LOCATION_CITY, NULL);
+
+    if (loc == NULL)
+        loc = gweather_location_get_world ();
+
+    lat = lat * M_PI / 180.0;
+    lon = lon * M_PI / 180.0;
+
+    data.latitude = lat;
+    data.longitude = lon;
+    data.location = NULL;
+    data.distance = 0.0;
+
+    foreach_city (loc, (GFunc) find_nearest_city, &data, func, user_data);
+
+    destroy (user_data);
 
     return gweather_location_ref (data.location);
 }
diff --git a/libgweather/gweather-location.h b/libgweather/gweather-location.h
index c97566f..63803a6 100644
--- a/libgweather/gweather-location.h
+++ b/libgweather/gweather-location.h
@@ -31,6 +31,7 @@
 G_BEGIN_DECLS
 
 typedef struct _GWeatherLocation GWeatherLocation;
+typedef gboolean (* GWeatherFilterFunc) (GWeatherLocation* location, gpointer user_data);
 
 typedef enum { /*< underscore_name=gweather_location_level >*/
     GWEATHER_LOCATION_WORLD,
@@ -73,6 +74,13 @@ GWeatherLocation      *gweather_location_find_nearest_city (GWeatherLocation *lo
                                                            double            lat,
                                                            double            lon);
 
+GWeatherLocation      *gweather_location_find_nearest_city_full (GWeatherLocation  *loc,
+                                                                double             lat,
+                                                                double             lon,
+                                                                GWeatherFilterFunc func,
+                                                                gpointer           user_data,
+                                                                GDestroyNotify     destroy);
+
 const char            *gweather_location_get_country    (GWeatherLocation  *loc);
 
 GWeatherTimezone      *gweather_location_get_timezone   (GWeatherLocation  *loc);