Implement -P, --pre-eval=CODE

Author: eraserhd

CHANGELOG.adoc

@@ -7,6 +7,11 @@ https://github.com/eraserhd/rep/compare/v0.2.2...HEAD[Unreleased]
 * Support for Mingw
 * Test on aarch64-darwin and aarch64-linux
 
+=== Added
+
+* `-P`, `--pre-eval` allows session initialization code which can do things
+  like connect to a Piggieback REPL.
+
 https://github.com/eraserhd/rep/compare/v0.2.1...v0.2.2[v0.2.2]
 ---------------------------------------------------------------
 

README.adoc

@@ -15,6 +15,11 @@ $ rep '(clojure.tools.namespace.repl/refresh)'
 :ok
 ....
 
+....
+$ rep -P '(cider.piggieback/cljs-repl :app)' '(.clear js/localStorage)'
+nil
+....
+
 Unlike other nREPL clients, `rep` does not try to maintain a persistent
 connection, meaning that thread-local variables and bindings like `*e` and
 `*1` will not persist across invocations of `rep`.  Perhaps there are

rep.1.adoc

@@ -49,6 +49,12 @@ connection, meaning that thread-local variables and bindings like `*e` and
     contains 'FNAME' and reads that file. The default is '@.nrepl-port@.',
     which will find the running nREPL if it was invoked by Leiningen.
 
+*-P, --pre-eval*=CODE::
+    CODE is evaluated in the new session before the main operation, and
+    output (except errors) is discarded.  This is useful to connect to
+    ClojureScript REPLs, for example
+    `--pre-eval='(cider.piggieback/cljs-repl :app)'`.
+
 *--print*=KEY[,FD[,FORMAT]]::
     Print response messages with KEY in them to FD, using FORMAT.  In FORMAT,
     `%{key}` prints *key* from the response message, `%%` prints a literal

rep.c

@@ -605,6 +605,7 @@ struct options
     _Bool help;
     struct print_option* print;
     _Bool verbose;
+    char* pre_eval;
 };
 
 struct sockaddr_in options_address(struct options* options, const char* port);
@@ -761,7 +762,7 @@ enum {
 };
 
 
-const char SHORT_OPTIONS[] = "hl:n:p:v";
+const char SHORT_OPTIONS[] = "hi:l:n:p:v";
 const struct option LONG_OPTIONS[] =
 {
     { "help",      0, NULL, 'h' },
@@ -770,6 +771,7 @@ const struct option LONG_OPTIONS[] =
     { "no-print",  1, NULL, OPT_NO_PRINT },
     { "op",        1, NULL, OPT_OP },
     { "port",      1, NULL, 'p' },
+    { "pre-eval",  1, NULL, 'P' },
     { "print",     1, NULL, OPT_PRINT },
     { "send",      1, NULL, OPT_SEND },
     { "verbose",   0, NULL, 'v' },
@@ -790,6 +792,7 @@ struct options* new_options(void)
     options->send = strdup("");
     options->print = make_default_print_options();
     options->verbose = false;
+    options->pre_eval = NULL;
     return options;
 }
 
@@ -881,6 +884,11 @@ struct options* parse_options(int argc, char* argv[])
             free(options->port);
             options->port = strdup(optarg);
             break;
+        case 'P':
+            if (options->pre_eval)
+                free(options->pre_eval);
+            options->pre_eval = strdup(optarg);
+            break;
         case 'v':
             options->verbose = true;
             break;
@@ -926,6 +934,8 @@ void free_options(struct options* options)
     if (options->send)
         free(options->send);
     free_print_options(options->print);
+    if (options->pre_eval)
+        free(options->pre_eval);
     free(options);
 }
 
@@ -1052,6 +1062,22 @@ int nrepl_exec(struct nrepl* nrepl)
 
     nrepl_send(nrepl, "d2:op5:clonee");
 
+    if (nrepl->options->pre_eval)
+    {
+        struct print_option *original_print = nrepl->options->print;
+        nrepl->options->print = make_print_option("err,2,%{err}");
+
+        nrepl_send(nrepl, "d2:op4:eval7:session%lu:%s4:code%lu:%se",
+            strlen(nrepl->session), nrepl->session,
+            strlen(nrepl->options->pre_eval), nrepl->options->pre_eval);
+
+        free_print_options(nrepl->options->print);
+        nrepl->options->print = original_print;
+
+        if (nrepl->exception_occurred)
+            return 1;
+    }
+
     char extra_options[512] = "";
     if (nrepl->options->line != -1)
         sprintf(extra_options + strlen(extra_options), "4:linei%de", nrepl->options->line);
@@ -1091,6 +1117,7 @@ Options:\n\
   --no-print=KEY                  Suppress output for KEY.\n\
   --op=OP                         nREPL operation (default: eval).\n\
   -p, --port=ADDRESS              TCP port, host:port, @portfile, or @FNAME@RELATIVE.\n\
+  -P, --pre-eval=CODE             Evaluated first, e.g. (cider.piggieback/cljs-repl :app).\n\
   --print=KEY|KEY,FD,FORMAT       Print FORMAT to FD when KEY is present.\n\
   --send=KEY,TYPE,VALUE           Send additional KEY of VALUE in request.\n\
   -v, --verbose                   Show all messages sent and received.\n\

test/rep/core_test.clj

@@ -74,3 +74,9 @@
 
 (facts "about the examples in the documentation"
   (rep "--op=ls-sessions" "--print=sessions,1,%{sessions,session=%.%n;}") => (prints #"^session=[a-fA-F0-9]{6}"))
+
+(facts "about pre-eval code"
+  (rep "--pre-eval=42" "(+ 2 2)")     => (prints "4\n")
+  (rep "--pre-eval=42" "(+ 2 2)")     => (exits-with 0)
+  (rep "--pre-eval=blergh" "(+ 2 2)") => (prints #"Unable to resolve symbol: blergh" :to-stderr)
+  (rep "--pre-eval=blergh" "(+ 2 2)") => (exits-with 1))