Add aggregating geocoder

README.md

@@ -27,6 +27,8 @@ The plugin supports many different data providers:
 - [ArcGIS](https://developers.arcgis.com/features/geocoding/)
 - [Azure Maps Geocoding](https://www.microsoft.com/en-us/maps/azure/location-services/geocoding)
 
+Multiple data providers can be combined by using the AggregatingGeocoder.
+
 The plugin can easily be extended to support other providers. Current extensions:
 
 - [DAWA Geocoder](https://github.com/kjoller/leaflet-control-geocoder-dawa/tree/new) - support for Danish Address Web API by [Niels Kjøller Hansen](https://github.com/kjoller)

spec/aggregating-geocoder.spec.ts

@@ -0,0 +1,39 @@
+import { describe, expect, it, vi } from 'vitest';
+import { AggregatingGeocoder, AgregatorOptions } from '../src/geocoders/aggregating-geocoder';
+import { LatLngLiteral } from 'leaflet';
+
+describe('L.Control.Geocoder.AggregatingGeocoder', () => {
+  it('geocde returns empty when no geocoders', async () => {
+    const options: AgregatorOptions = {
+      geocoders: []
+    }
+    const geocoder = new AggregatingGeocoder(options);
+
+    const results = await geocoder.geocode('foo');
+    expect(results).toEqual([]);
+  });
+
+  it('suggest returns empty when no geocoders', async () => {
+	  const options: AgregatorOptions = {
+	    geocoders: []
+	  }
+	  const geocoder = new AggregatingGeocoder(options);
+
+	  const results = await geocoder.suggest('foo');
+	  expect(results).toEqual([]);
+  });
+
+  it('reverse returns emtpy when no geocoders', async () => {
+    const options: AgregatorOptions = {
+	    geocoders: []
+    }
+    const geocoder = new AggregatingGeocoder(options);
+
+    const loc: LatLngLiteral = {
+      lat: 0,
+      lng: 0
+    };
+    const results = await geocoder.reverse(loc, 1);
+    expect(results).toEqual([]);
+  });
+});

src/geocoders/aggregating-geocoder.ts

@@ -0,0 +1,65 @@
+import * as L from 'leaflet';
+import { LatLngLiteral } from 'leaflet';
+import { IGeocoder, GeocodingContext, GeocodingResult } from './api';
+
+export interface AgregatorOptions {
+  geocoders: IGeocoder[];
+}
+
+/**
+ * Implementation of a geocoder that takes other geocoders and aggregates their results together.
+ **/
+export class AggregatingGeocoder implements IGeocoder {
+  options: AgregatorOptions = {
+    geocoders: []
+  }
+
+  constructor(options?: Partial<AgregatorOptions>) {
+    L.Util.setOptions(this, options)
+  }
+
+  private async combineResults(queries: Array<Promise<GeocodingResult[]>>): Promise<GeocodingResult[]> {
+    const queryResults: Array<GeocodingResult[]> = await Promise.all(queries);
+    const results: Array<GeocodingResult> = [];
+    for(const r of queryResults) {
+      results.push(...r);
+    }
+    return results;
+  }
+
+  geocode(query: string, context?: GeocodingContext): Promise<GeocodingResult[]> {
+    const queries: Promise<GeocodingResult[]>[] = [];
+    for(const geocoder of this.options.geocoders) {
+      queries.push(geocoder.geocode(query, context));
+    }
+    return this.combineResults(queries);
+  }
+
+  suggest?(query: string, context?: GeocodingContext): Promise<GeocodingResult[]> {
+    const queries: Promise<GeocodingResult[]>[] = [];
+	  for(const geocoder of this.options.geocoders) {
+      if (geocoder.suggest) {
+	      queries.push(geocoder.suggest(query, context));
+      }
+	  }
+    return this.combineResults(queries);
+  }
+
+  reverse?(location: LatLngLiteral, scale: number): Promise<GeocodingResult[]> {
+    const queries: Promise<GeocodingResult[]>[] = [];
+    for(const geocoder of this.options.geocoders) {
+      if (geocoder.reverse) {
+	      queries.push(geocoder.reverse(location, scale));
+      }
+    }
+    return this.combineResults(queries);
+  }
+}
+
+/**
+ * [Class factory method](https://leafletjs.com/reference.html#class-class-factories) for {@link AggregatingGeocoder}
+ * @param options the services to aggregate together.
+ */
+export function aggregatingGeocoder(options: Partial<AgregatorOptions>) {
+  return new AggregatingGeocoder(options);
+}

src/geocoders/index.ts

@@ -14,3 +14,4 @@ export * from './opencage';
 export * from './pelias';
 export * from './photon';
 export * from './what3words';
+export * from './aggregating-geocoder';