add initial support for loopback mode

via cljs_eval: https://clojureverse.org/t/status-update-inspect-cljs-eval/6074

Author: darwin

docs/faq.md

@@ -186,6 +186,18 @@
 > [this commit](https://github.com/binaryage/dirac-sample/commit/3f6b149eca7bac6efc6ffd77f29d25bdc1606d3c) how you could 
 > potentially implement something like this for your own project.
 
+#### What is loopback mode?
+
+> Shadow-cljs exposed experimental cljs_eval API. Please read [the announcement](https://clojureverse.org/t/status-update-inspect-cljs-eval/6074).
+> We can make use of this in shadow-cljs scenarios without any prior Dirac setup. 
+> If Dirac REPL is opened on a page which has no Dirac Runtime but has this API available, we can at least offer sugar 
+> on top of cljs_eval. When you type "some cljs code" into Dirac REPL and hit ENTER, it will be effectively turned into `await cljs_eval("some cljs code")`
+> Shadow-cljs will then do the compilation, evaluates generated javascript and you should see some results back in the console.
+> To switch current namespace enter `(in-ns 'your.new.namespace)`, this is handled specially by Dirac REPL.
+> I refer to this mode of operation as "loopback REPL". Because there is no Dirac nREPL backend or runtime support. 
+> Dirac talks to page's context to do cljs evaluations. Some Dirac features are not supported.
+> When this mode is active, you should see purple "loopback" indicator when the REPL prompt is empty.
+
 #### I have a great idea for contribution! How to hack on Dirac itself?
 
 > Please refer to [hacking.md](hacking.md).

resources/unpacked/devtools/front_end/console/ConsoleView.js

@@ -1740,8 +1740,10 @@ export class ConsoleView extends UI.Widget.VBox {
     const data =
         /** @type {{result: ?SDK.RemoteObject.RemoteObject, commandMessage: !SDK.ConsoleModel.ConsoleMessage, exceptionDetails: (!Protocol.Runtime.ExceptionDetails|undefined)}} */
         (event.data);
-    this._prompt.history().pushHistoryItem(data.commandMessage.messageText);
-    this._consoleHistorySetting.set(this._prompt.history().historyData().slice(-persistedHistorySize));
+    if (!data.commandMessage.skipHistory) {
+      this._prompt.history().pushHistoryItem(data.commandMessage.messageText);
+      this._consoleHistorySetting.set(this._prompt.history().historyData().slice(-persistedHistorySize));
+    }
     this._printResult(data.result, data.commandMessage, data.exceptionDetails);
   }
 

resources/unpacked/devtools/front_end/dirac/dirac.js

@@ -240,6 +240,9 @@ console.log("DJS imported!");
       return loadLazyDirac().then(() => window.dirac.addConsoleMessageToMainTarget(...args));
     }
 
+    function evaluateCommandInConsole(...args) {
+      return loadLazyDirac().then(() => window.dirac.evaluateCommandInConsole(...args));
+    }
     function registerDiracLinkAction(...args) {
       return loadLazyDirac().then(() => window.dirac.registerDiracLinkAction(...args));
     }
@@ -294,6 +297,7 @@ console.log("DJS imported!");
       subscribeDebuggerEvents: subscribeDebuggerEvents,
       unsubscribeDebuggerEvents: unsubscribeDebuggerEvents,
       addConsoleMessageToMainTarget: addConsoleMessageToMainTarget,
+      evaluateCommandInConsole: evaluateCommandInConsole,
       startListeningForWorkspaceChanges: startListeningForWorkspaceChanges,
       stopListeningForWorkspaceChanges: stopListeningForWorkspaceChanges,
       extractScopeInfoFromScopeChainAsync: extractScopeInfoFromScopeChainAsync,

resources/unpacked/devtools/front_end/dirac_lazy/dirac_lazy.js

@@ -197,6 +197,18 @@ Object.assign(window.dirac, (function() {
     SDK.consoleModel.addMessage(msg);
   }
 
+  function evaluateCommandInConsole(contextName, code) {
+    let context = contextName === "current" ? lookupCurrentContext() : lookupDefaultContext();
+    if (!context) {
+      console.warn("evaluateCommandInConsole got null '" +contextName+ "' context:", code);
+      return;
+    }
+    const commandMessage = new SDK.ConsoleMessage(context.runtimeModel, SDK.ConsoleMessage.MessageSource.JS, null, code, SDK.ConsoleMessage.MessageType.Command);
+    commandMessage.setExecutionContextId(context.id);
+    commandMessage.skipHistory = true;
+    SDK.consoleModel.evaluateCommandInConsole(context, commandMessage, code, false);
+  }
+
   // --- scope info -------------------------------------------------------------------------------------------------------
 
   function getScopeTitle(scope) {
@@ -919,6 +931,7 @@ Object.assign(window.dirac, (function() {
     subscribeDebuggerEvents: subscribeDebuggerEvents,
     unsubscribeDebuggerEvents: unsubscribeDebuggerEvents,
     addConsoleMessageToMainTarget: addConsoleMessageToMainTarget,
+    evaluateCommandInConsole: evaluateCommandInConsole,
     startListeningForWorkspaceChanges: startListeningForWorkspaceChanges,
     stopListeningForWorkspaceChanges: stopListeningForWorkspaceChanges,
     extractScopeInfoFromScopeChainAsync: extractScopeInfoFromScopeChainAsync,

src/implant/dirac/implant/eval.cljs

@@ -83,6 +83,16 @@
     :default (oget dirac "evalInDefaultContext")
     :current (oget dirac "evalInCurrentContext")))
 
+(defn get-context-name [context]
+  (case context
+    :default "default"
+    :current "current"))
+
+(defn eval-command-in-console! [context js-code]
+  (let [context-name (get-context-name context)]
+    (log (str "eval-command-in-console! [" context-name " context] > ") js-code)
+    (ocall (get-dirac) "evaluateCommandInConsole" context-name js-code)))
+
 (defn get-current-time []
   (.getTime (js/Date.)))
 
@@ -155,6 +165,9 @@
 (defn ^:dynamic console-log-template [method & args]
   (str "console." method "(" (string/join (interpose "," (map code-as-string args))) ")"))
 
+(defn ^:dynamic cljs-eval-template [code ns]
+  (str "await cljs_eval(" (code-as-string code) ", {'ns':" (code-as-string ns) "})"))
+
 (defn ^:dynamic prepare-install-playground-runtime-template [before includes after]
   (let [template (str before ";" (emit-install-playground-runtime-template))
         js-quote (fn [url] (str "'" url "'"))
@@ -484,3 +497,20 @@
         (if-not (= (first res) ::ok)
           (error "Failed to install playground runtime" res)
           (second res))))))
+
+; -- loopback REPL support --------------------------------------------------------------------------------------------------
+
+(defn go-ask-is-cljs-eval-present? []
+  (go
+    (let [res (<! (go-call-eval-with-timeout! :default "typeof cljs_eval" 2000 true))]
+      (if-not (= (first res) ::ok)
+        (do
+          (error "Failed to detect cljs_eval presence" (pr-str res))
+          false)
+        (do
+          (log "loopback available" (second res))
+          (= (second res) "function"))))))
+
+(defn eval-cljs-in-console! [code ns]
+  (let [js-code (cljs-eval-template code ns)]
+    (eval-command-in-console! :current js-code)))

src/implant/dirac/implant/intercom.cljs

@@ -15,7 +15,7 @@
             [dirac.shared.async :refer [<! close! go go-channel go-wait put!]]
             [dirac.shared.utils :as utils]
             [goog.functions :as gfns]
-            [oops.core :refer [oapply ocall oget gget]])
+            [oops.core :refer [oapply gcall ocall oget gget]])
   (:import goog.net.WebSocket.ErrorEvent))
 
 (def required-repl-api-version 9)
@@ -27,10 +27,12 @@
 (defonce ^:dynamic *last-session-id* nil)
 (defonce ^:dynamic *last-connect-fn-id* 0)
 (defonce ^:dynamic *ignore-next-client-change* false)
+(defonce ^:dynamic *loopback-repl-ns* nil)
 
 (def dirac-agent-help-url "https://github.com/binaryage/dirac/blob/master/docs/installation.md#start-dirac-agent")
 (def dirac-runtime-help-url "https://github.com/binaryage/dirac/blob/master/docs/installation.md#install-the-dirac-runtime")
 (def dirac-upgrading-help-url "https://github.com/binaryage/dirac/blob/master/docs/upgrading.md")
+(def dirac-loopback-mode-url "https://github.com/binaryage/dirac/blob/master/docs/faq.md#what-is-loopback-mode")
 
 (defn ^:dynamic repl-api-mismatch-msg [current-api required-api]
   (str "Dirac REPL API version mismatch detected.\n"
@@ -109,6 +111,9 @@
        "Normally we would inject playground project to get ad-hoc REPL working here "
        "but it is currently not supported with shadow-cljs."))
 
+(defn ^:dynamic explain-loopback-mode-msg []
+  (str "Dirac REPL is running in loopback mode. See " dirac-loopback-mode-url "."))
+
 (defn check-agent-version! [agent-version]
   (let [our-version implant-version/version]
     (when-not (= agent-version our-version)
@@ -164,6 +169,22 @@
   (set! *repl-connected* false)
   (set! *last-connect-fn-id* 0))
 
+(defn loopback-repl? []
+  (= *last-connection-url* "loopback-repl"))
+
+(defn update-loopback-repl! []
+  (console/set-prompt-ns! *loopback-repl-ns*)
+  (console/set-prompt-compiler! "loopback" ""))
+
+(defn connect-to-loopback-repl! []
+  (set! *last-connection-url* "loopback-repl")
+  (set! *last-session-id* "loopback-session")
+  (set! *repl-bootstrapped* true)
+  (set! *repl-connected* true)
+  (set! *loopback-repl-ns* "cljs.user")
+  (update-repl-mode!)
+  (update-loopback-repl!))
+
 (defn on-client-change [_key _ref old new]
   (when-not *ignore-next-client-change*
     (if (some? new)
@@ -263,15 +284,47 @@
     (js->clj scope-info-js :keywordize-keys true)
     {}))
 
+(def dirac-special-re #"\(?dirac!?.*\)?")
+(def in-ns-re #"\(in-ns\s+'?(.*)\)")
+
+(defn is-dirac-special? [code]
+  (some? (re-matches dirac-special-re code)))
+
+(defn is-in-ns-call? [code]
+  (some? (re-matches in-ns-re code)))
+
+(defn handle-dirac-special! []
+  (gcall "dirac.addConsoleMessageToMainTarget" "log" "info" (explain-loopback-mode-msg))
+  ::command-handled)
+
+(defn handle-in-ns-call! [code]
+  (let [m (re-matches in-ns-re code)
+        ns (second m)]
+    (when (some? ns)
+      (set! *loopback-repl-ns* ns)
+      (update-loopback-repl!)
+      ::command-handled)))
+
+(defn attempt-to-handle-loopback-repl-specials! [code]
+  (cond
+    (is-dirac-special? code) (handle-dirac-special!)
+    (is-in-ns-call? code) (handle-in-ns-call! code)))
+
+(defn do-loopback-repl-eval! [code]
+  (if-not (= ::command-handled (attempt-to-handle-loopback-repl-specials! code))
+    (eval/eval-cljs-in-console! code *loopback-repl-ns*)))
+
 (defn send-eval-request! [job-id code scope-info]
-  (when (repl-ready?)
-    (console/announce-job-start! job-id (str "eval: " code))
-    (let [message {:op         "eval"
-                   :dirac      "short-circuit-presentation"
-                   :id         job-id
-                   :code       code
-                   :scope-info (prepare-scope-info scope-info)}]
-      (nrepl-tunnel-client/tunnel-message! (utils/compact message)))))
+  (if-not (loopback-repl?)
+    (when (repl-ready?)
+      (console/announce-job-start! job-id (str "eval: " code))
+      (let [message {:op         "eval"
+                     :dirac      "short-circuit-presentation"
+                     :id         job-id
+                     :code       code
+                     :scope-info (prepare-scope-info scope-info)}]
+        (nrepl-tunnel-client/tunnel-message! (utils/compact message))))
+    (do-loopback-repl-eval! code)))
 
 (defn ws-url [host port]
   (str "ws://" host ":" port))
@@ -311,6 +364,12 @@
     (register-bootstrap-done-hook! enter-playground!)
     (<! (go-init-repl! true))))
 
+(defn go-start-loopback-repl! []
+  (feedback/post! "start-loopback-repl!")
+  (go
+    (connect-to-loopback-repl!)
+    (<! (go-init-repl! true))))
+
 (declare go-react-on-global-object-cleared!)
 
 (defn on-debugger-event [type & args]
@@ -342,11 +401,13 @@
           (if (<! (eval/go-ask-is-runtime-repl-enabled?))
             (<! (go-start-repl!))
             (display-prompt-status (repl-support-not-enabled-msg)))
-          (if (or no-playground? (hosted?))
-            (display-prompt-status (missing-runtime-msg runtime-present?))
-            (if (<! (eval/go-ask-is-shadow-present?))
-              (display-prompt-status (no-playground-due-to-shadow-msg))
-              (<! (go-start-playground-repl!)))))))))
+          (if (<! (eval/go-ask-is-cljs-eval-present?))
+            (<! (go-start-loopback-repl!))
+            (if (or no-playground? (hosted?))
+              (display-prompt-status (missing-runtime-msg runtime-present?))
+              (if (<! (eval/go-ask-is-shadow-present?))
+                (display-prompt-status (no-playground-due-to-shadow-msg))
+                (<! (go-start-playground-repl!))))))))))
 
 (defn go-react-on-global-object-cleared! []
   (reset-repl-state!)