pass reference to global-state object when creating feature filter

Author: melitele

src/feature_filter/feature_filter.test.ts

@@ -97,6 +97,12 @@ describe('filter', () => {
         expect(withinFilter.filter({zoom: 3}, featureInTile, canonical)).toBe(false);
     });
 
+    test('expression, global-state', () => {
+        const {filter} = featureFilter(['==', ['global-state', 'x'], ['get', 'x']], {x: 1});
+        expect(filter(undefined, {properties: {x: 1}} as any as Feature)).toBe(true);
+        expect(filter(undefined, {properties: {x: 2}} as any as Feature)).toBe(false);
+    });
+
     legacyFilterTests(featureFilter);
 
 });

src/feature_filter/index.ts

@@ -75,10 +75,11 @@ const filterSpec = {
  * passes its test.
  *
  * @private
- * @param {Array} filter MapLibre filter
- * @returns {Function} filter-evaluating function
+ * @param filter MapLibre filter
+ * @param [globalState] Global state object to be used for evaluating 'global-state' expressions
+ * @returns filter-evaluating function
  */
-export function featureFilter(filter: any): FeatureFilter {
+export function featureFilter(filter: any, globalState?: Record<string, any>): FeatureFilter {
     if (filter === null || filter === undefined) {
         return {filter: () => true, needGeometry: false, getGlobalStateRefs: () => new Set()};
     }
@@ -87,7 +88,7 @@ export function featureFilter(filter: any): FeatureFilter {
         filter = convertFilter(filter);
     }
 
-    const compiled = createExpression(filter, filterSpec as StylePropertySpecification);
+    const compiled = createExpression(filter, filterSpec as StylePropertySpecification, globalState);
     if (compiled.result === 'error') {
         throw new Error(compiled.value.map(err => `${err.key}: ${err.message}`).join(', '));
     } else {