search: refactor to swap search library #407

see lunr-adapter.js to see how other search engines can be integrated

search: fix comments #407

search: adapter docs #407

search: fix triggered search #407

layouts/_relearn_searchform/views/article.html

@@ -6,7 +6,7 @@
 {{ partial "heading-pre.html" . }}{{ partial "heading.html" . }}{{ partial "heading-post.html" . }}
 
 <search>
-  <form action="javascript:triggerSearch()">
+  <form action="javascript:window.relearn.executeTriggeredSearch()">
     <div class="searchform">
       <label class="a11y-only" for="R-search-by-detail">{{ T "Search" }}</label>
       <input data-search-input id="R-search-by-detail" class="search-by" name="search-by" type="search" placeholder="{{ T "Search-placeholder" }}">

layouts/partials/search.html

@@ -69,5 +69,5 @@
           {{- $file := (printf "js/lunr/lunr.%s.min.js" .) }}
         <script src="{{ $file | relURL}}{{ $assetBusting }}" defer></script>
         {{- end }}
-        <script src="{{ "js/search.js" | relURL }}{{ $assetBusting }}" defer></script>
+        <script src="{{ "js/search.js" | relURL }}{{ $assetBusting }}" type="module" defer></script>
       {{- end }}

layouts/partials/version.txt

@@ -1 +1 @@
-7.1.1
+7.1.1+28fce6b04c414523280c53ee02f9f3a94d9d23da

static/js/lunr-adapter.js

@@ -0,0 +1,136 @@
+/*
+
+# Adapter Interface
+
+The search adapter needs to provide the following functions that are called from search.js
+
+## init()
+
+Initialize the search engine and the search index
+
+### Parameters
+
+none
+
+### Returns
+
+none
+
+### Remarks
+
+Once successfully completed, needs to call
+
+	````
+    window.relearn.isSearchEngineReady = true;
+    window.relearn.executeInitialSearch();
+	````
+
+## search()
+
+Performs the search and returs found results.
+
+### Parameters
+
+term: string // the search term that was typed in by the user
+
+### Returns
+
+Must return an array of found pages, sorted with the most relevant page first.
+
+Each array item needs the following layout:
+
+````
+{
+    index: string, // optional, id of the page in the search index
+    matches: string[], // optional, TODO: have to find out what it does
+    page: {
+        breadcrumb: string,
+        title: string,
+        uri: string,
+        content: string,
+        tags: string[]
+    }
+}
+````
+*/
+
+let lunrIndex, pagesIndex;
+
+function init() {
+    function initLunrIndex( index ){
+        pagesIndex = index;
+        // Set up Lunr by declaring the fields we use
+        // Also provide their boost level for the ranking
+        lunrIndex = lunr(function() {
+            this.use(lunr.multiLanguage.apply(null, contentLangs));
+            this.ref('index');
+            this.field('title', {
+                boost: 15
+            });
+            this.field('tags', {
+                boost: 10
+            });
+            this.field('content', {
+                boost: 5
+            });
+
+            this.pipeline.remove(lunr.stemmer);
+            this.searchPipeline.remove(lunr.stemmer);
+
+            // Feed Lunr with each file and let index them
+            pagesIndex.forEach(function(page, idx) {
+                page.index = idx;
+                this.add(page);
+            }, this);
+        });
+
+        window.relearn.isSearchEngineReady = true;
+        window.relearn.executeInitialSearch();
+    }
+
+    if( window.index_js_url ){
+        var js = document.createElement("script");
+        js.src = index_js_url;
+        js.setAttribute("async", "");
+        js.onload = function(){
+            initLunrIndex(relearn_searchindex);
+        };
+        js.onerror = function(e){
+            console.error('Error getting Hugo index file');
+        };
+        document.head.appendChild(js);
+    }
+}
+
+function search(term) {
+    function searchPatterns(word) {
+        // for short words high amounts of typos doesn't make sense
+        // for long words we allow less typos because this largly increases search time
+        var typos = [
+            { len:  -1, typos: 1 },
+            { len:  60, typos: 2 },
+            { len:  40, typos: 3 },
+            { len:  20, typos: 4 },
+            { len:  16, typos: 3 },
+            { len:  12, typos: 2 },
+            { len:   8, typos: 1 },
+            { len:   4, typos: 0 },
+        ];
+        return [
+            word + '^100',
+            word + '*^10',
+            '*' + word + '^10',
+            word + '~' + typos.reduce( function( a, c, i ){ return word.length < c.len ? c : a; } ).typos + '^1'
+        ];
+    }
+
+    // Find the item in our index corresponding to the Lunr one to have more info
+    // Remove Lunr special search characters: https://lunrjs.com/guides/searching.html
+    term = term.replace( /[*:^~+-]/g, ' ' );
+    var searchTerm = lunr.tokenizer( term ).reduce( function(a,token){return a.concat(searchPatterns(token.str))}, []).join(' ');
+    return !searchTerm || !lunrIndex ? [] : lunrIndex.search(searchTerm).map(function(result) {
+        return { index: result.ref, matches: Object.keys(result.matchData.metadata), page: pagesIndex[ result.ref ] };
+    });
+}
+
+export { init, search };