module extension: add support for canonical name resolution (#2013)

Before attempting to load a module, each provided resolver must be given an
opportunity to examine the name of the requested module without actually
loading it so as to canonicalize it, in case a module can be referred to by
multiple names.

Then, modules are loaded and cached by their canonical name.

JerryScript-DCO-1.0-Signed-off-by: Gabriel Schulhof gabriel.schulhof@intel.com

tests/unit-ext/module/jerry-module-test.c

@@ -60,11 +60,18 @@ const char eval_string5[] =
 "  return x === y ? 1 : 0;"
 "}) ();";
 
+/*
+ * Define a resolver for a module named "differently-handled-module" to check that custom resolvers work.
+ */
 static bool
-resolve_differently_handled_module (const jerry_char_t *name,
-                                                jerry_value_t *result)
+resolve_differently_handled_module (const jerry_value_t name,
+                                    jerry_value_t *result)
 {
-  if (!strcmp ((char *) name, "differently-handled-module"))
+  jerry_size_t name_size = jerry_get_utf8_string_size (name);
+  jerry_char_t name_string[name_size];
+  jerry_string_to_utf8_char_buffer (name, name_string, name_size);
+
+  if (!strncmp ((char *) name_string, "differently-handled-module", name_size))
   {
     (*result) = jerry_create_number (29);
     return true;
@@ -72,16 +79,26 @@ resolve_differently_handled_module (const jerry_char_t *name,
   return false;
 } /* resolve_differently_handled_module */
 
+static jerryx_module_resolver_t differently_handled_module_resolver =
+{
+  NULL,
+  resolve_differently_handled_module
+};
+
 /*
  * Define module "cache-check" via its own resolver as an empty object. Since objects are accessible only via references
  * we can strictly compare the object returned on subsequent attempts at loading "cache-check" with the object returned
  * on the first attempt and establish that the two are in fact the same object - which in turn shows that caching works.
  */
 static bool
-cache_check (const jerry_char_t *name,
+cache_check (const jerry_value_t name,
              jerry_value_t *result)
 {
-  if (!strcmp ((char *) name, "cache-check"))
+  jerry_size_t name_size = jerry_get_utf8_string_size (name);
+  jerry_char_t name_string[name_size];
+  jerry_string_to_utf8_char_buffer (name, name_string, name_size);
+
+  if (!strncmp ((char *) name_string, "cache-check", name_size))
   {
     (*result) = jerry_create_object ();
     return true;
@@ -89,13 +106,19 @@ cache_check (const jerry_char_t *name,
   return false;
 } /* cache_check */
 
-static const jerryx_module_resolver_t resolvers[3] =
+static jerryx_module_resolver_t cache_check_resolver =
 {
-  jerryx_module_native_resolver,
-  resolve_differently_handled_module,
+  NULL,
   cache_check
 };
 
+static const jerryx_module_resolver_t *resolvers[3] =
+{
+  &jerryx_module_native_resolver,
+  &differently_handled_module_resolver,
+  &cache_check_resolver
+};
+
 static jerry_value_t
 handle_require (const jerry_value_t js_function,
                 const jerry_value_t this_val,
@@ -107,16 +130,9 @@ handle_require (const jerry_value_t js_function,
   (void) args_count;
 
   jerry_value_t return_value = 0;
-  jerry_char_t module_name[256] = "";
-  jerry_size_t bytes_copied = 0;
 
   TEST_ASSERT (args_count == 1);
-  bytes_copied = jerry_string_to_char_buffer (args_p[0], module_name, 256);
-  if (bytes_copied < 256)
-  {
-    module_name[bytes_copied] = 0;
-    return_value = jerryx_module_resolve (module_name, resolvers, 3);
-  }
+  return_value = jerryx_module_resolve (args_p[0], resolvers, 3);
 
   return return_value;
 } /* handle_require */

tests/unit-ext/test-ext-module-canonical.c

@@ -0,0 +1,107 @@
+/* Copyright JS Foundation and other contributors, http://js.foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <string.h>
+
+#include "jerryscript.h"
+#include "test-common.h"
+#include "jerryscript-ext/module.h"
+
+#define ACTUAL_NAME "alice"
+#define ALIAS_NAME "bob"
+
+static jerry_value_t
+get_canonical_name (const jerry_value_t name)
+{
+  jerry_size_t name_size = jerry_get_string_size (name);
+  jerry_char_t name_string[name_size + 1];
+  jerry_string_to_char_buffer (name, name_string, name_size);
+  name_string[name_size] = 0;
+
+  if (!strcmp ((char *) name_string, ACTUAL_NAME))
+  {
+    return jerry_acquire_value (name);
+  }
+  else if (!strcmp ((char *) name_string, ALIAS_NAME))
+  {
+    return jerry_create_string ((jerry_char_t *) ACTUAL_NAME);
+  }
+  else
+  {
+    return jerry_create_undefined ();
+  }
+} /* get_canonical_name */
+
+static bool
+resolve (const jerry_value_t canonical_name, jerry_value_t *result)
+{
+  jerry_size_t name_size = jerry_get_string_size (canonical_name);
+  jerry_char_t name_string[name_size + 1];
+  jerry_string_to_char_buffer (canonical_name, name_string, name_size);
+  name_string[name_size] = 0;
+
+  if (!strcmp ((char *) name_string, ACTUAL_NAME))
+  {
+    *result = jerry_create_object ();
+    return true;
+  }
+  return false;
+} /* resolve */
+
+static const jerryx_module_resolver_t canonical_test =
+{
+  .get_canonical_name_p = get_canonical_name,
+  .resolve_p = resolve
+};
+
+#define TEST_VALUE 95.0
+
+int
+main (int argc, char **argv)
+{
+  (void) argc;
+  (void) argv;
+
+  const jerryx_module_resolver_t *resolver = &canonical_test;
+
+  jerry_init (JERRY_INIT_EMPTY);
+
+  jerry_value_t actual_name = jerry_create_string ((jerry_char_t *) ACTUAL_NAME);
+  jerry_value_t alias_name = jerry_create_string ((jerry_char_t *) ALIAS_NAME);
+
+  /* It's important that we resolve by the non-canonical name first. */
+  jerry_value_t result2 = jerryx_module_resolve (alias_name, &resolver, 1);
+  jerry_value_t result1 = jerryx_module_resolve (actual_name, &resolver, 1);
+  jerry_release_value (actual_name);
+  jerry_release_value (alias_name);
+
+  /* An elaborate way of doing strict equal - set a property on one object and it "magically" appears on the other. */
+  jerry_value_t prop_name = jerry_create_string ((jerry_char_t *) "something");
+  jerry_value_t prop_value = jerry_create_number (TEST_VALUE);
+  jerry_release_value (jerry_set_property (result1, prop_name, prop_value));
+  jerry_release_value (prop_value);
+
+  prop_value = jerry_get_property (result2, prop_name);
+  TEST_ASSERT (jerry_get_number_value (prop_value) == TEST_VALUE);
+  jerry_release_value (prop_value);
+
+  jerry_release_value (prop_name);
+  jerry_release_value (result1);
+  jerry_release_value (result2);
+
+  jerry_cleanup ();
+
+  return 0;
+} /* main */

tests/unit-ext/test-ext-module-empty.c

@@ -26,12 +26,15 @@ main (int argc, char **argv)
   (void) argv;
   jerry_char_t buffer[256];
   jerry_size_t bytes_copied;
-  jerryx_module_resolver_t resolver = jerryx_module_native_resolver;
+  const jerryx_module_resolver_t *resolver = &jerryx_module_native_resolver;
+  jerry_value_t module_name;
 
   jerry_init (JERRY_INIT_EMPTY);
 
   /* Attempt to load a non-existing module. */
-  jerry_value_t module = jerryx_module_resolve ((jerry_char_t *) "some-unknown-module-name", &resolver, 1);
+  module_name = jerry_create_string ((jerry_char_t *) "some-unknown-module-name");
+  jerry_value_t module = jerryx_module_resolve (module_name, &resolver, 1);
+  jerry_release_value (module_name);
 
   TEST_ASSERT (jerry_value_has_error_flag (module));