enhance(search): util to match region names in search query

packages/@ourworldindata/utils/src/index.ts

@@ -35,6 +35,7 @@ export {
     isTouchDevice,
     type Json,
     csvEscape,
+    escapeRegExp,
     urlToSlug,
     trimObject,
     fetchText,

site/search/SearchUtils.tsx

@@ -0,0 +1,24 @@
+import {
+    Region,
+    getRegionByNameOrVariantName,
+    regions,
+    escapeRegExp,
+} from "@ourworldindata/utils"
+
+const allCountryNamesAndVariants = regions.flatMap((c) => [
+    c.name,
+    ...(("variantNames" in c && c.variantNames) || []),
+])
+
+// A RegExp that matches any country, region and variant name. Case-independent.
+const regionNameRegex = new RegExp(
+    `\\b(${allCountryNamesAndVariants.map(escapeRegExp).join("|")})\\b`,
+    "gi"
+)
+
+export const extractRegionNamesFromSearchQuery = (query: string) => {
+    const matches = query.matchAll(regionNameRegex)
+    const regionNames = Array.from(matches, (match) => match[0])
+    if (regionNames.length === 0) return null
+    return regionNames.map(getRegionByNameOrVariantName) as Region[]
+}