Web assembly build with emscripten.

src/webclient/main.c

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+/*
+* Copyright (c) 2018 Calvin Rose
+*
+* Permission is hereby granted, free of charge, to any person obtaining a copy
+* of this software and associated documentation files (the "Software"), to
+* deal in the Software without restriction, including without limitation the
+* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+* sell copies of the Software, and to permit persons to whom the Software is
+* furnished to do so, subject to the following conditions:
+*
+* The above copyright notice and this permission notice shall be included in
+* all copies or substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+* IN THE SOFTWARE.
+*/
+
+#include <janet/janet.h>
+#include <generated/webinit.h>
+#include <emscripten.h>
+
+static JanetFiber *repl_fiber = NULL;
+static JanetBuffer *line_buffer = NULL;
+static const uint8_t *line_prompt = NULL;
+
+/* Yield to JS event loop from janet. Takes a repl prompt
+ * and a buffer to fill with input data. */
+static int repl_yield(JanetArgs args) {
+    JANET_FIXARITY(args, 2);
+    JANET_ARG_STRING(line_prompt, args, 0);
+    JANET_ARG_BUFFER(line_buffer, args, 1);
+    /* Suspend janet repl by throwing a user defined signal */
+    return JANET_SIGNAL_USER9;
+}
+
+/* Re-enter the loop */
+static int enter_loop(void) {
+    Janet ret;
+    JanetSignal status = janet_continue(repl_fiber, janet_wrap_nil(), &ret);
+    if (status == JANET_SIGNAL_ERROR) {
+        janet_stacktrace(repl_fiber, "runtime", ret);
+        janet_deinit();
+        repl_fiber = NULL;
+        return 1;
+    }
+    return 0;
+}
+
+/* Intialize the repl */
+EMSCRIPTEN_KEEPALIVE
+void repl_init(void) {
+    int status;
+    JanetTable *env;
+
+    /* Set up VM */
+    janet_init();
+    env = janet_core_env();
+
+    /* Janet line getter */
+    janet_def(env, "repl-yield", janet_wrap_cfunction(repl_yield));
+    janet_register("repl-yield", janet_wrap_cfunction(repl_yield));
+
+    /* Run startup script */
+    Janet ret;
+    status = janet_dobytes(env, janet_gen_webinit, sizeof(janet_gen_webinit), "webinit.janet", &ret);
+    if (status == JANET_SIGNAL_ERROR) {
+        printf("start up error.\n");
+        janet_deinit();
+        repl_fiber = NULL;
+        return;
+    }
+    janet_gcroot(ret);
+    repl_fiber = janet_unwrap_fiber(ret);
+
+    /* Start repl */
+    if (enter_loop()) return;
+}
+
+/* Deinitialize the repl */
+EMSCRIPTEN_KEEPALIVE
+void repl_deinit(void) {
+    if (!repl_fiber) {
+        return;
+    }
+    repl_fiber = NULL;
+    line_buffer = NULL;
+    janet_deinit();
+}
+
+/* Get the prompt to show in the repl */
+EMSCRIPTEN_KEEPALIVE
+const char *repl_prompt(void) {
+    return line_prompt ? ((const char *)line_prompt) : "";
+}
+
+/* Restart the repl calling from JS. Pass in the input for the next line. */
+EMSCRIPTEN_KEEPALIVE
+void repl_input(char *input) {
+
+    /* Create the repl if we haven't yet */
+    if (!repl_fiber) {
+        printf("initialize the repl first");
+    }
+
+    /* Now fill the pending line_buffer and resume the repl loop */
+    if (line_buffer) {
+        janet_buffer_push_cstring(line_buffer, input);
+        line_buffer = NULL;
+        enter_loop();
+    }
+}

src/webclient/webinit.janet

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+# Copyright 2017-2018 (C) Calvin Rose
+(print (string "Janet " janet.version "  Copyright (C) 2017-2018 Calvin Rose"))
+
+(fiber.new 
+  (fn @[]
+    (repl (fn [buf p]
+            (def [line] (parser.where p))
+            (def prompt (string "janet:" line ":" (parser.state p) "> "))
+            (repl-yield prompt buf)
+            buf)))
+  :9e) # stop fiber on error signals and user9 signals