[new] [Experimental] Add :experimental/compact-vectors? option to `…

…get-default-resource-compiler`

Trades off additional CPU time to produce more compact compiled vector resources.
Can be net more efficient when used with Reactjs, etc.

There may be opportunities to do more of this at compile time, but it's not clear
that the benefits would be worth the additional complexity/effort.

src/taoensso/tempura.cljc

@@ -27,34 +27,68 @@
 
 ;;;;
 
+(defn- compact [xs]
+  (let [[x0 & xn] xs
+        out
+        (loop [[x1 & xn*] xn
+               acc [x0]
+               sb  nil]
+
+          (cond
+            (nil?    x1) (if sb (conj acc (str sb)) acc)
+            (vector? x1)
+            (recur xn*
+              (conj
+                (if sb (conj acc (str sb)) acc)
+                (compact x1)) nil)
+
+            :else
+            (recur xn* acc
+              (if sb
+                (enc/sb-append sb (str x1))
+                (enc/str-builder  (str x1))))))]
+
+    (if (and (== (count out) 2) (enc/kw-identical? (nth out 0) :span))
+      (nth out 1)
+      (do  out))))
+
+(comment (enc/qb 1e4 (compact [:span "a" "b" [:strong "c" "d"] "e" "f"])))
+
 (def get-default-resource-compiler
   "Implementation detail.
   Good general-purpose resource compiler.
   Supports output of text, and Hiccup forms with simple Markdown styles."
   (enc/fmemoize
-    (fn [{:keys [default-tag escape-html?]
+    (fn [{:keys [default-tag escape-html? experimental/compact-vectors?]
           :or   {default-tag :span}}]
 
-      (let [esc1 (if escape-html? impl/escape-html             identity)
-            esc2 (if escape-html? impl/vec-escape-html-in-strs identity)]
+      (let [?esc1    (if escape-html?     impl/escape-html             identity)
+            ?esc2    (if escape-html?     impl/vec-escape-html-in-strs identity)
+            ?compact (if compact-vectors? (fn [f] (comp compact f))    identity)]
 
         (enc/fmemoize
           (fn [res] ; -> [(fn [vargs]) -> <compiled-resource>]
             (enc/cond! ; Nb no keywords, nils, etc.
               (fn?     res) (-> res) ; Completely arb, full control
-              (string? res) (-> res esc1 impl/str->vargs-fn)
-              (vector? res) (-> res
-                              (impl/vec->vtag default-tag)
-                              impl/vec-explode-styles-in-strs
-                              impl/vec-explode-args-in-strs
-                              esc2 ; Avoid for Reactjs
-                              impl/vec->vargs-fn))))))))
+              (string? res) (-> res ?esc1 impl/str->vargs-fn)
+              (vector? res)
+              (?compact ; [:span "foo" "bar"] -> "foobar", etc.
+                (-> res
+                  (impl/vec->vtag default-tag)
+                  impl/vec-explode-styles-in-strs
+                  impl/vec-explode-args-in-strs
+                  ?esc2              ; Avoid for Reactjs
+                  impl/vec->vargs-fn ; (fn [args]) -> result
+                  )))))))))
 
 (comment
-  (let [rc (get-default-resource-compiler {})]
-    [((rc  "Hi %1 :-)")  ["Steve"])
-     ((rc  "Hi **%1**")  ["Steve"])
-     ((rc ["Hi **%1**"]) ["Steve"])]))
+  (let [rc (get-default-resource-compiler
+             {:experimental/compact-vectors? #_false true})]
+
+    [((rc "Hi %1 :-)")           ["Steve"])
+     ((rc "Hi **%1** :-)")       ["Steve"])
+     ((rc ["a **b %1 c** d %2"]) [1 2])
+     ((rc ["a" "b"])             [])]))
 
 (def default-tr-opts
   {:default-locale :en
@@ -315,8 +349,10 @@
 (comment
   (tr {} [:en] [:resid1 "Hello there"])   ; => text
   (tr {} [:en] [:resid1 ["Hello world"]]) ; => vec (Hiccup, etc.)
+  (tr {} [:en] [:resid1 ["Hello %1"]] ["Steve"])
   (tr {} [:en] [:resid2 ["Hello **world**"]])
   (tr {} [:en] [:resid3 ["Hello " [:br] [:strong "world"]]])
+  (tr {} [:en] [["foo"]])
 
   (def c1
     {:cache-dict?    false