title: Mapbox gl js - Custom icons based on multiple criteria
body: <p>I'm currently trying to build a customer web map with mapbox gl js and struggle how to best structure the code to display the geojson data on the map layer based on multiple properties.</p>
  <p>Properties are as follows:</p>
  <ul>
  <li>type: includes the property of the marker with 3 values: static,
  airplane, ship</li>
  <li>name: include the name of the marker, can be any name for ship and
  airplane but defines a sub type for static: airport, building, bridge</li>
  <li>nation: includes a numeric value based on the nation the above items belongs to: 0, 1, 2</li>
  </ul>
  <p>Type and name will define the icon type, nation the icon color (icons are in sdf format)</p>
  <p>I have the following code now which works but without taking the name subclass for static objects into account. Any suggestion on how this subclass match can be included so I can show different icons for static+airport, static+building, static+bridge but not care about the name for the airplane and ship types?</p>
  <pre><code>map.addLayer({
          'id': 'marker',
          'type': 'symbol',
          'source': 'db-json',
          'layout': {
              'icon-image': [
                      'match', // Use the 'match' expression: https://docs.mapbox.com/mapbox-gl-js/style-spec/#expressions-match
                      ['get', 'type'], // Use the result 'coalition' property
                      'airplane', 'plane-icon',
                      'static', 'circle-stroked-15',
                      'ship', 'harbor-15',
                      'airfield-15' // any other type
                      ]
              },
              'paint': {
                  'icon-color': [
                      'match', // Use the 'match' expression: https://docs.mapbox.com/mapbox-gl-js/style-spec/#expressions-match
                      ['get', 'nation'], // Use the result 'nation' property
                      0, '#808080',
                      1, '#FF0000',
                      2, '#0000FF',
                      '#00FF00' // any other nation
                      ]
                  }
          });
  </code></pre>
  <p>Thanks a million !!</p>