eval: implement -m option to preload modules

The -m option instructs the interpreter to automatically require the named
module and to register the module context as global variable.

The following two commands are equivalent, with the former one serving as
a shortcut for the latter:

    utpl -m fs -s '{{ fs.open("test.txt").read("all") }}'
    utpl -s '{% fs = require("fs"); print(fs.open("test.txt").read("all")) %}'

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

1 files changed, 19 insertions, 1 deletions

diff --git a/eval.c b/eval.c
index c05d80a..c8a5910 100644
--- a/eval.c
+++ b/eval.c
@@ -1557,10 +1557,11 @@ ut_register_variable(struct json_object *scope, const char *key, struct json_obj
 }
 
 enum ut_error_type
-ut_run(struct ut_state *state, struct json_object *env)
+ut_run(struct ut_state *state, struct json_object *env, struct json_object *modules)
 {
 	struct ut_op *op = ut_get_op(state, state->main);
 	struct json_object *entry, *scope, *args, *rv;
+	size_t i;
 
 	if (!op || op->type != T_FUNC) {
 		ut_exception(state, state->main, "Runtime error: Invalid root operation in AST");
@@ -1589,6 +1590,23 @@ ut_run(struct ut_state *state, struct json_object *env)
 	ut_lib_init(state, scope);
 
 	args = json_object_new_array();
+
+	if (modules) {
+		for (i = 0; i < json_object_array_length(modules); i++) {
+			json_object_array_put_idx(args, 0, json_object_get(json_object_array_get_idx(modules, i)));
+
+			rv = ut_invoke(state, state->main, NULL,
+			               json_object_object_get(scope, "require"),
+			               args);
+
+			ut_register_variable(scope,
+			                     json_object_get_string(json_object_array_get_idx(modules, i)),
+			                     rv);
+		}
+
+		json_object_array_del_idx(args, 0, 1);
+	}
+
 	rv = ut_invoke(state, state->main, NULL, entry, args);
 
 	json_object_put(entry);