Improved search experience in many languages

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

@@ -58,9 +58,9 @@ export interface SearchIndexDocument {
  * Search index pipeline function
  */
 export type SearchIndexPipelineFn =
-  | "stemmer"                          /* Stemmer */
-  | "stopWordFilter"                   /* Stop word filter */
   | "trimmer"                          /* Trimmer */
+  | "stopWordFilter"                   /* Stop word filter */
+  | "stemmer"                          /* Stemmer */
 
 /**
  * Search index pipeline
@@ -92,6 +92,25 @@ export interface SearchResult {
   sections: SectionDocument[]          /* Section documents */
 }
 
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Compute the difference of two lists of strings
+ *
+ * @param a - 1st list of strings
+ * @param b - 2nd list of strings
+ *
+ * @return Difference
+ */
+function difference(a: string[], b: string[]): string[] {
+  const [x, y] = [new Set(a), new Set(b)]
+  return [
+    ...new Set([...x].filter(value => !y.has(value)))
+  ]
+}
+
 /* ----------------------------------------------------------------------------
  * Class
  * ------------------------------------------------------------------------- */
@@ -147,15 +166,20 @@ export class Search {
           this.use((lunr as any).multiLanguage(...config.lang))
         }
 
-        /* Set up pipeline according to configuration */
-        this.pipeline.reset()
-        for (const fn of pipeline!)
-          this.pipeline.add(lunr[fn])
+        /* Compute functions to be removed from the pipeline */
+        const fns = difference([
+          "trimmer", "stopWordFilter", "stemmer"
+        ], pipeline!)
 
-        /* Set up search pipeline according to configuration */
-        this.searchPipeline.reset()
-        for (const fn of pipeline!)
-          this.searchPipeline.add(lunr[fn])
+        /* Remove functions from the pipeline for every language */
+        for (const lang of config.lang.map(language => (
+          language === "en" ? lunr : (lunr as any)[language]
+        ))) {
+          for (const fn of fns) {
+            this.pipeline.remove(lang[fn])
+            this.searchPipeline.remove(lang[fn])
+          }
+        }
 
         /* Set up fields and reference */
         this.field("title", { boost: 1000 })

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

@@ -51,5 +51,5 @@ export function defaultTransform(value: string): string {
   return value
     .replace(/(?:^|\s+)[*+-:^~]+(?=\s+|$)/g, "")
     .trim()
-    .replace(/\s+|\b$/g, "* ")
+    .replace(/\s+|(?![^\x00-\x7F]|^)$|\b$/g, "* ")
 }