From e50ccd4a6fd9e2b057d2401aefa21298934c2140 Mon Sep 17 00:00:00 2001
From: Michiel Borkent <michielborkent@gmail.com>
Date: Mon, 30 Oct 2023 18:13:43 +0100
Subject: [PATCH] Add time macro

---
 src/sci/impl/namespaces.cljc | 20 +++++++++++++++++++-
 test/sci/core_test.cljc      | 12 ++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/src/sci/impl/namespaces.cljc b/src/sci/impl/namespaces.cljc
index 8715547b..1bc872ae 100644
--- a/src/sci/impl/namespaces.cljc
+++ b/src/sci/impl/namespaces.cljc
@@ -11,7 +11,8 @@
                             print-method
                             print-dup
                             #?(:cljs alter-meta!)
-                            memfn])
+                            memfn
+                            time])
   (:require
    #?(:clj [clojure.edn :as edn]
       :cljs [cljs.reader :as edn])
@@ -986,6 +987,20 @@
   #?(:clj  (list 'new 'clojure.lang.LazySeq (list* '^{:once true} fn* [] body))
      :cljs `(new cljs.core/LazySeq nil (fn [] ~@body) nil nil)))
 
+(defn time
+  "Evaluates expr and prints the time it took. Returns the value of expr."
+  [_ _ expr]
+  `(let [start# (clojure.core/system-time)
+           ret# ~expr]
+       (prn (str "Elapsed time: "
+                 #?(:clj (/ (double (- (clojure.core/system-time) start#)) 1000000.0)
+                    :cljs (.toFixed (- (clojure.core/system-time) start#) 6))
+                 " msecs"))
+       ret#))
+
+#?(:clj (defn system-time []
+          (System/nanoTime)))
+
 (macros/usetime
 
  (def clojure-core
@@ -1489,10 +1504,13 @@
     ;;            'this-as (macrofy 'this-as this-as clojure-core-ns)])
     'test (copy-core-var test)
     'thread-bound? (copy-var sci-thread-bound? clojure-core-ns {:name 'thread-bound?})
+    'time (copy-var time clojure-core-ns {:macro true})
     'subs (copy-core-var subs)
     #?@(:clj ['supers (copy-core-var supers)])
     'symbol (copy-var symbol* clojure-core-ns {:name 'symbol})
     'symbol? (copy-core-var symbol?)
+    'system-time (copy-var #?(:clj system-time
+                              :cljs system-time) clojure-core-ns)
     'special-symbol? (copy-core-var special-symbol?)
     'subvec (copy-core-var subvec)
     'some-fn (copy-core-var some-fn)
diff --git a/test/sci/core_test.cljc b/test/sci/core_test.cljc
index f399f240..d1f8d7c2 100644
--- a/test/sci/core_test.cljc
+++ b/test/sci/core_test.cljc
@@ -1666,6 +1666,18 @@
    (deftest queue-test
      (is (= #queue [1 2 3] (sci/eval-string "#queue [1 2 3]")))))
 
+(deftest time-test
+  #?(:clj
+     (let [output (java.io.StringWriter.)]
+       (is (= 1 (sci/binding [sci/out output] (sci/eval-string "(time 1)"))))
+       (is (re-matches #"\"Elapsed time: \d\.\d+ msecs\"\s+" (str output))))
+     :cljs
+     (let [output (atom "")
+           print-fn #(swap! output str %)]
+       (is (= 1 (sci/binding [sci/print-fn print-fn] (sci/eval-string "(time 1)" {:classes {'js js/globalThis :allow :all}}))))
+       (is (re-matches #"\"Elapsed time: \d\.\d+ msecs\"" @output))))
+  )
+
 ;;;; Scratch
 
 (comment