Begin writing MRL answering system

nlmaps_tools/answer_mrl.py

+import argparse
+import json
+import sys
+
+import jinja2
+from OSMPythonTools.overpass import Overpass
+
+from nlmaps_tools.parse_mrl import MrlGrammar, Symbol
+
+
+OVERPASS_URL = 'https://overpass-api.de/api/interpreter'
+
+ENV = jinja2.Environment(
+    loader=jinja2.PackageLoader('nlmaps_tools', 'overpass_templates'),
+    trim_blocks=True,
+    lstrip_blocks=True,
+    autoescape=False,
+)
+
+ENV.globals['esc'] = lambda x: x
+
+#area(3600062422)->.a;(node(area.a)["shop"="bakery"];way(area.a)["shop"="bakery"];relation(area.a)["shop"="bakery"];);out;
+
+
+def has_name(tags):
+    return any(key == 'name' for key, _ in tags)
+
+
+def geojson(elements):
+    features = [elm.geometry() for elm in elements]
+    return {'type': 'FeatureCollection', 'features': features}
+
+
+def element_name(element):
+    name = element.tag('name')
+    if name:
+        return name
+    return element.id()
+
+
+def apply_qtype(qtype, elements):
+    if qtype == Symbol('latlong'):
+        return {'type': 'map'}
+    elif qtype == ('least', ('topx', Symbol('1'))):
+        text = 'Yes' if len(elements) > 0 else 'No'
+        return {'type': 'text', 'text': text}
+    elif qtype == Symbol('count'):
+        return {'type': 'text', 'text': str(len(elements))}
+    elif qtype == Symbol('count'):
+        return {'type': 'text', 'text': str(len(elements))}
+    elif isinstance(qtype, tuple) and qtype[0] == 'findkey':
+        # TODO: Handle multiple keys
+        key = qtype[1]
+        name = lambda elm: elm.id() if key == 'name' else element_name(elm)
+        values = ['{}: {}'.format(name(elm), str(elm.tag(key)))
+                  for elm in elements]
+        return {'type': 'list', 'list': values}
+    return {'type': 'Error', 'error': 'Unknown qtype: {}'.format(qtype)}
+
+
+def answer_in_query(features, overpass_url=OVERPASS_URL):
+    overpass = Overpass()
+    if 'area' in features:
+        template = ENV.get_template('in_query/area.jinja2')
+    elif has_name(features['target_nwr']):
+        template = ENV.get_template('in_query/name.jinja2')
+    else:
+        ans = {}
+        ans['type'] = 'error'
+        ans['error'] = 'No area and no name=* tag present.'
+        return ans
+
+    ql = template.render(features=features)
+    result = overpass.query(ql)
+    elements = result.elements()
+
+    answers = {'type': 'sub', 'sub': [], 'geojson': geojson(elements)}
+    for qtype in features['qtype']:
+        answers['sub'].append(apply_qtype(qtype, elements))
+    return answers
+
+
+def answer(features):
+    if features['query_type'] == 'in_query':
+        return answer_in_query(features)
+    return {
+        'type': 'error',
+        'error': 'query_type {} not supported yet'.format(
+            features['query_type'])
+    }
+
+
+def load_features(mrl, escaped=False):
+    mrl = mrl.strip()
+    if mrl.startswith('dist(') or mrl.startswith('query('):
+        grammar = MrlGrammar()
+        try:
+            parseResult = grammar.parseMrl(mrl, is_escaped=escaped)
+        except:
+            print('Could not parse MRL: {}'.format(mrl), file=sys.stderr)
+            sys.exit(1)
+        features = parseResult['features']
+    elif isinstance(mrl, dict) and 'query_type' in mrl:
+        features = mrl
+    else:
+        try:
+            features = json.loads(mrl)
+        except:
+            print('Could not load MRL features from following JSON: {}'
+                  .format(mrl), file=sys.stderr)
+            sys.exit(1)
+    return features
+
+
+def main(mrl, escaped=False):
+    features = load_features(mrl, escaped=escaped)
+    print(features)
+    print(answer(features))
+
+
+def parse_args():
+    parser = argparse.ArgumentParser(description='Answer an MRL')
+    parser.add_argument(
+        'mrl',
+        help='MRL as string or MRL features as json string'
+    )
+    parser.add_argument(
+        '--escaped', action='store_true', default=False,
+        help='Whether the mrl is in escaped form. Default: False'
+    )
+    args = parser.parse_args()
+    return args
+
+
+if __name__ == '__main__':
+    ARGS = parse_args()
+    main(**vars(ARGS))
+

nlmaps_tools/overpass_templates/in_query/area.jinja2

+area[name="{{ esc(features['area']) }}"]->.a;
+nwr(area.a){##}
+{% for key, val in features['target_nwr'] %}
+["{{ esc(key) }}"="{{ esc(val) }}"]{##}
+{% endfor %}
+;
+out geom;

nlmaps_tools/overpass_templates/in_query/name.jinja2

+nwr(area.a){##}
+{% for key, val in features['target_nwr'] %}
+["{{ esc(key) }}"="{{ esc(val) }}"]{##}
+{% endfor %}
+;
+out geom;