Add universal weather data downloader

docs/GLM/Global/Geocode.md

@@ -0,0 +1,51 @@
+[[/GLM/Global/Geocode]] -- Geohash encoder
+
+# Synopsis
+
+GLM:
+
+~~~
+${GEOCODE <latitude>,<longitude>[#<resolution>]}
+${GEOCODE <objname>[#<resolution>]}
+~~~
+
+# Description
+
+Return the geohash code corresponding to the latitude/longitude given or the object name. This can be helpful is connecting object based on location, such as linking an object to weather.
+
+The default resolution is 5. The resolution corresponds to the following distances:
+
+    1   2500 km
+    2   600 km
+    3   80 km
+    4   20 km
+    5   2.5 km
+    6   0.2 km
+    7   0.08 km
+    8   0.02 km
+    9   0.0025 km
+    10  0.0006 km
+    11  0.000075 km
+
+# Example
+
+The following example prints the geohash codes for a position and an object:
+
+~~~
+class test
+{
+    char32 geocode;
+}
+object test
+{
+    name "test";
+    latitude 37.5;
+    longitude -122.2;
+}
+#print ${GEOCODE 37.5,-122.2#6}
+#print ${GEOCODE test#6}
+~~~
+
+# See also
+
+* [[/GLM/Subcommand/Geodata]]

docs/GLM/Macro/Ifexist.md

@@ -34,11 +34,8 @@ The `#ifexist` macro is used to conditionally process GLM lines when a file is f
 #endif
 ~~~
 
-# Caveats
-
-1. TODO enumerate known issues using Ifexist
-
 # See also
 
 * [[/Glm/Macro/If]]
+* [[/Glm/Macro/Ifmissing]]
 

docs/GLM/Macro/Ifmissing.md

@@ -0,0 +1,41 @@
+[[/Glm/Macro/Ifmissing]] -- Macro to conditionally process GLM lines when a file missing
+
+# Synopsis
+
+GLM:
+
+~~~
+#ifmissing <path-name>
+...
+[#else]
+...
+#endif
+~~~
+
+or
+
+~~~
+#ifmissing "<path-name>"
+...
+[#else]
+...
+#endif
+~~~
+
+# Description
+
+The `#ifmissing` macro is used to conditionally process GLM lines when a file is not found.
+
+# Examples
+
+~~~
+#ifmissing "myfile.glm"
+#print didn't find it
+#endif
+~~~
+
+# See also
+
+* [[/Glm/Macro/If]]
+* [[/Glm/Macro/Ifexist]]
+

gldcore/autotest/test_geocode.glm

@@ -0,0 +1,21 @@
+#set suppress_repeat_messages=false
+
+class test
+{
+	char32 geocode;
+}
+
+object test
+{
+	name "test";
+	latitude 37.5;
+	longitude -122.2;
+}
+
+#if ${GEOCODE 37.5,-122.2#6} != 9q9j76
+#error geocode "37.5,-122.2#6" does not match "9q9j76"
+#endif
+
+#if ${GEOCODE test#6} != 9q9j76
+#error geocode "test#6" does not match "9q9j76"
+#endif

gldcore/globals.cpp

@@ -1437,6 +1437,93 @@ DEPRECATED const char *global_findobj(char *buffer, int size, const char *spec)
     return buffer;
 }
 
+const char *geocode_encode(char *buffer, int len, double lat, double lon, int resolution=12)
+{
+	static const char *base32 = "0123456789bcdefghjkmnpqrstuvwxyz";
+	if ( len < resolution+1 )
+	{
+		output_warning("geocode_encode(buffer=%p, len=%d, lat=%g, lon=%g, resolution=%d): buffer too small for specified resolution, result truncated", 
+			buffer, len, lat, lon, resolution);
+		resolution = len-1;
+	}
+	double lat_interval[] = {-90,90};
+	double lon_interval[] = {-180,180};
+	char *geohash = buffer;
+	geohash[0] = '\0';
+	int bits[] = {16,8,4,2,1};
+	int bit = 0;
+	int ch = '\0';
+	bool even = true;
+	int i = 0;
+	while ( i < resolution )
+	{
+		if ( even )
+		{
+			double mid = (lon_interval[0]+lon_interval[1])/2;
+			if ( lon > mid )
+			{
+				ch |= bits[bit];
+				lon_interval[0] = mid;
+			}
+			else
+			{
+				lon_interval[1] = mid;
+			}
+		}
+		else
+		{
+			double mid = (lat_interval[0]+lat_interval[1])/2;
+			if ( lat > mid )
+			{
+				ch |= bits[bit];
+				lat_interval[0] = mid;
+			}
+			else
+			{
+				lat_interval[1] = mid;
+			}
+		}
+		even = !even;
+		if ( bit < 4 )
+		{
+			bit += 1;
+		}
+		else
+		{
+			*geohash++ = base32[ch];
+			i++;
+			bit = 0;
+			ch = 0;
+		}
+	}
+	*geohash++ = '\0';
+	return buffer;
+}
+
+DEPRECATED const char *global_geocode(char *buffer, int size, const char *spec)
+{
+	double lat, lon;
+	OBJECT *obj;
+	unsigned int res = 5; // about 2.4 km resolution by default
+	char name[64];
+	if ( sscanf(spec,"%lg,%lg#%u",&lat,&lon,&res) >= 2 )
+	{
+		return geocode_encode(buffer,size,lat,lon,res);
+	}
+	else if ( sscanf(spec,"%63[^#]#%u",name,&res) >= 1 && (obj=object_find_name(name)) != NULL )
+	{
+		lat = obj->latitude;
+		lon = obj->longitude;
+		if ( isfinite(lat) && isfinite(lon) && lat>=-90 && lat<=+90 && lon>=-180 && lon<=180 )
+		{
+			return geocode_encode(buffer,size,lat,lon,res);
+		}
+	}
+	output_warning("${GEOCODE %s}: geocode spec is not valid",spec);
+	buffer[0] = '\0';
+	return buffer;
+}
+
 /** Get the value of a global variable in a safer fashion
 	@return a \e char * pointer to the buffer holding the buffer where we wrote the data,
 		\p NULL if insufficient buffer space or if the \p name was not found.
@@ -1531,6 +1618,10 @@ const char *GldGlobals::getvar(const char *name, char *buffer, size_t size)
     if ( strncmp(name,"FIND ",5) == 0 )
     {
         return global_findobj(buffer,size,name+5);
+    }
+    if ( strncmp(name,"GEOCODE ",8) == 0 )
+    {
+    	return global_geocode(buffer,size,name+8);
     }
 	/* expansions */
 	if ( parameter_expansion(buffer,size,name) )