2 files changed, 36 insertions, 3 deletions

diff --git a/objects.js b/objects.js
index 3bdda48..0f77351 100644
--- a/objects.js
+++ b/objects.js
@@ -219,12 +219,16 @@ SpriteMorph.prototype.initBlocks = function () {
             spec: 'lat, lon of %s',
             defaults: ['Tiergarten Berlin']
         },
-        // TODO: move these to a 'map' category or so
         reportGeocode: {
             type: 'reporter',
             category: 'motion',
             spec: 'address at lon: %n lat: %n'
         },
+        overpassQuerySucceeds: {
+            type: 'predicate',
+            category: 'motion',
+            spec: 'overpass query %s returns elements'
+        },
         focusMap: {
             type: 'command',
             category: 'motion',
@@ -1778,9 +1782,14 @@ SpriteMorph.prototype.blockTemplates = function (category) {
     if (cat === 'motion') {
         blocks.push(block('userLon'));
         blocks.push(block('userLat'));
+        blocks.push('-');
+        blocks.push(block('overpassQuerySucceeds'));
+        blocks.push('-');
         blocks.push(block('reportGeocode'));
         blocks.push(block('findLocation'));
+        blocks.push('-');
         blocks.push(block('focusMap'));
+        blocks.push('-');
 
         //if (this.world().isDevMode) {
             blocks.push(block('addMarker'));
diff --git a/threads.js b/threads.js
index e2eeae9..1804737 100644
--- a/threads.js
+++ b/threads.js
@@ -2642,6 +2642,30 @@ Process.prototype.addMarker = function (pos) {
     L.marker(pos.contents).addTo(window.map);
 };
 
+// Nesting reporters that 'doYield' sucks; as a workaround,
+// there is a library imported that uses this function.
+// TODO: Improve this :)
+//
+// returns true if there are elements returned by the overpass query
+Process.prototype.overpassQuerySucceeds = function (query) {
+    var url = 'overpass-api.de/api/interpreter?data=[out:json];'
+        + query;
+
+    var response;
+    if (!this.httpRequest) {
+        this.httpRequest = new XMLHttpRequest();
+        this.httpRequest.open("GET", 'http://' + url, true);
+        this.httpRequest.send(null);
+    } else if (this.httpRequest.readyState === 4) {
+        response = this.httpRequest.responseText;
+        this.httpRequest = null;
+        console.log(response); // DEBUG
+        return JSON.parse(response).elements.length > 0;
+    }
+    this.pushContext('doYield');
+    this.pushContext();
+};
+
 Process.prototype.reportGeocode = function (lon, lat) {
     var myself = this;
 
@@ -2666,7 +2690,7 @@ Process.prototype.reportGeocode = function (lon, lat) {
 
     this.pushContext('doYield');
     this.pushContext();
-}
+};
 
 Process.prototype.findLocation = function (searchString) {
     var myself = this;
@@ -2693,7 +2717,7 @@ Process.prototype.findLocation = function (searchString) {
 
     this.pushContext('doYield');
     this.pushContext();
-}
+};
 
 // Process Dates and times in Snap
 // Map block options to built-in functions