[next] Bootstrap plugins directly (#1698)

pyscript.core/src/config.js

@@ -0,0 +1,44 @@
+/**
+ * This file parses a generic <py-config> or config attribute
+ * to use as base config for all py-script elements, importing
+ * also a queue of plugins *before* the interpreter (if any) resolves.
+ */
+import { $ } from "basic-devtools";
+
+import allPlugins from "./plugins.js";
+import { robustFetch as fetch, getText } from "./fetch.js";
+
+// TODO: this is not strictly polyscript related but handy ... not sure
+//       we should factor this utility out a part but this works anyway.
+import { parse } from "../node_modules/polyscript/esm/toml.js";
+
+// find the shared config for all py-script elements
+let config, plugins, parsed;
+let pyConfig = $("py-config");
+if (pyConfig) config = pyConfig.getAttribute("src") || pyConfig.textContent;
+else {
+    pyConfig = $('script[type="py"][config]');
+    if (pyConfig) config = pyConfig.getAttribute("config");
+}
+
+// load its content if remote
+if (/^https?:\/\//.test(config)) config = await fetch(config).then(getText);
+
+// parse config only if not empty
+if (config?.trim()) {
+    try {
+        parsed = JSON.parse(config);
+    } catch (_) {
+        parsed = await parse(config);
+    }
+}
+
+// parse all plugins and optionally ignore only
+// those flagged as "undesired" via `!` prefix
+const toBeAwaited = [];
+for (const [key, value] of Object.entries(allPlugins)) {
+    if (!parsed?.plugins?.includes(`!${key}`)) toBeAwaited.push(value());
+}
+if (toBeAwaited.length) plugins = Promise.all(toBeAwaited);
+
+export { config, plugins };