ENH: Show type-dependent icon on search result entries

It's helpful to visually distinguish different content types.

This PR adds `itemType` to the javascript result entries
(one of "title", "index", "object", "text") and adds
them as a class to the <li> item in the result list.
This allows styling via CSS.

For simplicity, I've styled with unicode symbols, which
should give a decent look without the need to ship our
own symbols. Derived themes have the ability to adapt
this via their CSS settings.

sphinx/themes/basic/static/basic.css_t

@@ -114,16 +114,25 @@ img {
 
 /* -- search page ----------------------------------------------------------- */
 
-ul.search {
-    margin: 10px 0 0 20px;
-    padding: 0;
-}
-
 ul.search li {
     padding: 5px 0 5px 20px;
-    background-image: url(file.png);
-    background-repeat: no-repeat;
-    background-position: 0 7px;
+    list-style: "\25A1";  /* Unicode: White Square */
+}
+
+ul.search li.title {
+    list-style: "\1F4C1";  /* Unicode: File Folder */
+}
+
+ul.search li.index {
+    list-style: "\1F4D1";  /* Unicode: Bookmark Tabs */
+}
+
+ul.search li.object {
+    list-style: "\1F4E6";  /* Unicode: Package */
+}
+
+ul.search li.text {
+    list-style: "\1F4C4";  /* Unicode: Page Facing Up */
 }
 
 ul.search li a {

sphinx/themes/basic/static/searchtools.js

@@ -20,7 +20,7 @@ if (typeof Scorer === "undefined") {
     // and returns the new score.
     /*
     score: result => {
-      const [docname, title, anchor, descr, score, filename] = result
+      const [docname, title, anchor, descr, score, filename, itemType] = result
       return score
     },
     */
@@ -64,9 +64,10 @@ const _displayItem = (item, searchTerms, highlightTerms) => {
   const showSearchSummary = DOCUMENTATION_OPTIONS.SHOW_SEARCH_SUMMARY;
   const contentRoot = document.documentElement.dataset.content_root;
 
-  const [docName, title, anchor, descr, score, _filename] = item;
+  const [docName, title, anchor, descr, score, _filename, itemType] = item;
 
   let listItem = document.createElement("li");
+  listItem.classList.add(itemType)
   let requestUrl;
   let linkUrl;
   if (docBuilder === "dirhtml") {
@@ -138,7 +139,7 @@ const _displayNextItem = (
   else _finishSearch(resultCount);
 };
 // Helper function used by query() to order search results.
-// Each input is an array of [docname, title, anchor, descr, score, filename].
+// Each input is an array of [docname, title, anchor, descr, score, filename, itemType].
 // Order the results by score (in opposite order of appearance, since the
 // `_displayNextItem` function uses pop() to retrieve items) and then alphabetically.
 const _orderResultsByScoreThenName = (a, b) => {
@@ -318,7 +319,7 @@ const Search = {
     const indexEntries = Search._index.indexentries;
 
     // Collect multiple result groups to be sorted separately and then ordered.
-    // Each is an array of [docname, title, anchor, descr, score, filename].
+    // Each is an array of [docname, title, anchor, descr, score, filename, itemType].
     const normalResults = [];
     const nonMainIndexResults = [];
 
@@ -336,6 +337,7 @@ const Search = {
             null,
             score,
             filenames[file],
+            "title",
           ]);
         }
       }
@@ -353,6 +355,7 @@ const Search = {
             null,
             score,
             filenames[file],
+            "index",
           ];
           if (isMain) {
             normalResults.push(result);
@@ -474,6 +477,7 @@ const Search = {
         descr,
         score,
         filenames[match[0]],
+        "object",
       ]);
     };
     Object.keys(objects).forEach((prefix) =>
@@ -584,6 +588,7 @@ const Search = {
         null,
         score,
         filenames[file],
+        "text",
       ]);
     }
     return results;