Experiment to render viewers to html string

Author: mk

notebooks/hello.clj

@@ -6,8 +6,9 @@
   (:require [nextjournal.clerk :as clerk]))
 
 ;; Here's a visualization of unemployment in the US.
-(clerk/vl {:width 700 :height 400 :data {:url "https://vega.github.io/vega-datasets/data/us-10m.json"
-                                         :format {:type "topojson" :feature "counties"}}
-           :transform [{:lookup "id" :from {:data {:url "https://vega.github.io/vega-datasets/data/unemployment.tsv"}
-                                            :key "id" :fields ["rate"]}}]
-           :projection {:type "albersUsa"} :mark "geoshape" :encoding {:color {:field "rate" :type "quantitative"}}})
+#_(clerk/vl {:width 700 :height 400 :data {:url "https://vega.github.io/vega-datasets/data/us-10m.json"
+                                           :format {:type "topojson" :feature "counties"}}
+             :transform [{:lookup "id" :from {:data {:url "https://vega.github.io/vega-datasets/data/unemployment.tsv"}
+                                              :key "id" :fields ["rate"]}}]
+             :projection {:type "albersUsa"} :mark "geoshape" :encoding {:color {:field "rate" :type "quantitative"}}})
+

notebooks/html_string.clj

@@ -0,0 +1,97 @@
+;; # HTML String Rendering
+
+;; This is an experiment to find out what's required to support
+;; rendering to HTML strings via hiccup, using an alternative viewer
+;; stack. If this is feasible, it could be the basis for a much
+;; smaller client-side bundle in combination with a morphing lib while
+;; moving some of the viewers implementation to custom elements.
+
+(ns html-string
+  (:require [nextjournal.clerk :as clerk]
+            [nextjournal.clerk.eval :as eval]
+            [nextjournal.clerk.view :as view]
+            [nextjournal.clerk.viewer :as viewer]
+            [clojure.repl.deps :as deps]))
+
+(defn render-cell [xs]
+  (apply list xs))
+
+(defn render-notebook [{xs :blocks :keys [package doc-css-class sidenotes? toc toc-visibility header footer]}
+                       #_{:as render-opts :keys [!expanded-at]}]
+  [:div.flex
+   [:div.flex-auto.w-screen.scroll-container
+    (into
+     [:div
+      (merge
+       {#_#_:key "notebook-viewer"
+        :class (cond-> (or doc-css-class (mapv name [:flex :flex-col :items-center :notebook-viewer :flex-auto]))
+                 sidenotes? (conj :sidenotes-layout))})]
+     (concat (when header [header]) xs (when footer [footer])))]])
+
+(defn render-html [html]
+  html)
+
+(defn render-code-block [code-string #_{:as opts :keys [id]}]
+  [:div.viewer.code-viewer.w-full.max-w-wide #_{:data-block-id id}
+   code-string
+   #_
+   [code/render-code code-string (assoc opts :language "clojure")]])
+
+(defn render-toc [_])
+
+(def modified-viewers
+  [(assoc viewer/cell-viewer :render-fn `render-cell)
+   (assoc viewer/notebook-viewer :render-fn `render-notebook)
+   (assoc viewer/code-block-viewer :render-fn `render-code-block)
+   (assoc viewer/html-viewer :render-fn `render-html)
+   (assoc viewer/toc-viewer :render-fn `render-toc)])
+
+(defn doc->viewer [doc]
+  (viewer/present
+   (viewer/with-viewers (viewer/add-viewers modified-viewers)
+     (viewer/notebook doc))))
+
+(def viewer-doc
+  (doc->viewer (eval/eval-file "notebooks/hello.clj")))
+
+(defn extract-viewers [viewer-doc]
+  (into []
+        (keep :nextjournal/viewer)
+        (tree-seq coll? seq viewer-doc)))
+
+(sort (keys (frequencies (mapv (comp :form :render-fn) (extract-viewers viewer-doc)))))
+
+(defn ->fn [sym]
+  (cond
+    (simple-symbol? sym) (ns-resolve 'clojure.core sym)
+    (qualified-symbol? sym) (requiring-resolve sym)
+    :else (throw (ex-info "->fn expected symbol, got" {:sym sym}))))
+
+(defn eval-viewers [viewer-doc]
+  (clojure.walk/postwalk (fn [x]
+                           (if (and (map? x)
+                                    (contains? x :nextjournal/viewer)
+                                    (contains? x :nextjournal/value))
+                             ((->fn (get-in x [:nextjournal/viewer :render-fn :form]))
+                              (:nextjournal/value x))
+                             x))
+                         viewer-doc))
+#_
+(clerk/present! (viewer/html
+                 (eval-viewers viewer-doc)))
+
+(defonce html
+  (do
+    (deps/add-lib 'io.github.escherize/huff)
+    @(requiring-resolve 'huff2.core/html)))
+
+(defn ->html [viewer-doc]
+  (nextjournal.clerk.view/->html {:exclude-js? true
+                                  :html (html (eval-viewers viewer-doc))}))
+
+(doto "test.html"
+  (spit (->html viewer-doc))
+  (clojure.java.browse/browse-url))
+
+
+

src/nextjournal/clerk/viewer.cljc

@@ -793,7 +793,7 @@
    {:name :nextjournal.markdown/heading
     :transform-fn (into-markup
                    (fn [{:keys [attrs heading-level]}]
-                     [(str "h" heading-level) attrs]))}
+                     [(keyword (str "h" heading-level)) attrs]))}
    {:name :nextjournal.markdown/image
     :transform-fn (fn [{node :nextjournal/value}]
                     (with-viewer `html-viewer