Implemented support for AND search with quotation marks

material/assets/manifest.json

@@ -1,6 +1,6 @@
 {
-  "assets/javascripts/bundle.js": "assets/javascripts/bundle.38f5c9b5.min.js",
-  "assets/javascripts/bundle.js.map": "assets/javascripts/bundle.38f5c9b5.min.js.map",
+  "assets/javascripts/bundle.js": "assets/javascripts/bundle.8db80c2a.min.js",
+  "assets/javascripts/bundle.js.map": "assets/javascripts/bundle.8db80c2a.min.js.map",
   "assets/javascripts/vendor.js": "assets/javascripts/vendor.de50e36d.min.js",
   "assets/javascripts/vendor.js.map": "assets/javascripts/vendor.de50e36d.min.js.map",
   "assets/javascripts/worker/search.js": "assets/javascripts/worker/search.9b3611bd.min.js",

material/base.html

@@ -183,7 +183,7 @@ <h1>{{ page.title | default(config.site_name, true)}}</h1>
     </div>
     {% block scripts %}
       <script src="{{ 'assets/javascripts/vendor.de50e36d.min.js' | url }}"></script>
-      <script src="{{ 'assets/javascripts/bundle.38f5c9b5.min.js' | url }}"></script>
+      <script src="{{ 'assets/javascripts/bundle.8db80c2a.min.js' | url }}"></script>
       {%- set translations = {} -%}
       {%- for key in [
         "clipboard.copy",

src/assets/javascripts/integrations/search/transform/index.ts

@@ -40,16 +40,38 @@ export type SearchTransformFn = (value: string) => string
 /**
  * Default transformation function
  *
- * Rogue control characters are filtered before handing the query to the
- * search index, as `lunr` will throw otherwise.
+ * 1. Search for terms in quotation marks and prepend a `+` modifier to denote
+ *    that the resulting document must contain all terms, converting the query
+ *    to and `AND` query (as opposed to the default `OR` behavior). While users
+ *    may expected terms enclosed in quotation marks to map to span queries,
+ *    i.e. for which order is important, `lunr` doesn't support them, so the
+ *    best we can do is to convert the terms to an `AND` query.
+ *
+ * 2. Replace control characters which are not located at the beginning of the
+ *    query or preceded by white space, or are not followed by a non-whitespace
+ *    character or are at the end of the query string. Furthermore, filter
+ *    unmatched quotation marks.
+ *
+ * 3. Trim excess whitespace from left and right.
+ *
+ * 4. Append a wildcard to the end of every word to make every word a prefix
+ *    query in order to provide a good type-ahead experience, by adding an
+ *    asterisik (wildcard) in between terms, which can be denoted by whitespace,
+ *    any non-control character, or a word boundary.
  *
  * @param value - Query value
  *
  * @return Transformed query value
  */
 export function defaultTransform(value: string): string {
   return value
-    .replace(/(?:^|\s+)[*+\-:^~]+(?=\s+|$)/g, "")
-    .trim()
-    .replace(/\s+|(?![^\x00-\x7F]|^)$|\b$/g, "* ")
+    .split(/"([^"]+)"/)                             /* => 1 */
+      .map((terms, i) => i & 1
+        ? terms.replace(/^\b|^(?![^\x00-\x7F]|$)|\s+/g, " +")
+        : terms
+      )
+      .join("")
+    .replace(/"|(?:^|\s+)[*+\-:^~]+(?=\s+|$)/g, "") /* => 2 */
+    .trim()                                         /* => 3 */
+    .replace(/\s+|(?![^\x00-\x7F]|^)$|\b$/g, "* ")  /* => 4 */
 }