/*
* Node.js-like module loading framework for Duktape
*
* https://nodejs.org/api/modules.html
*/
#include "duktape.h"
#include "duk_module_node.h"
#if DUK_VERSION >= 19999
static duk_int_t duk__eval_module_source(duk_context *ctx, void *udata);
#else
static duk_int_t duk__eval_module_source(duk_context *ctx);
#endif
static void duk__push_module_object(duk_context *ctx, const char *id, duk_bool_t main);
static duk_bool_t duk__get_cached_module(duk_context *ctx, const char *id) {
duk_push_global_stash(ctx);
(void) duk_get_prop_string(ctx, -1, "\xff" "requireCache");
if (duk_get_prop_string(ctx, -1, id)) {
duk_remove(ctx, -2);
duk_remove(ctx, -2);
return 1;
} else {
duk_pop_3(ctx);
return 0;
}
}
/* Place a `module` object on the top of the value stack into the require cache
* based on its `.id` property. As a convenience to the caller, leave the
* object on top of the value stack afterwards.
*/
static void duk__put_cached_module(duk_context *ctx) {
/* [ ... module ] */
duk_push_global_stash(ctx);
(void) duk_get_prop_string(ctx, -1, "\xff" "requireCache");
duk_dup(ctx, -3);
/* [ ... module stash req_cache module ] */
(void) duk_get_prop_string(ctx, -1, "id");
duk_dup(ctx, -2);
duk_put_prop(ctx, -4);
duk_pop_3(ctx); /* [ ... module ] */
}
static void duk__del_cached_module(duk_context *ctx, const char *id) {
duk_push_global_stash(ctx);
(void) duk_get_prop_string(ctx, -1, "\xff" "requireCache");
duk_del_prop_string(ctx, -1, id);
duk_pop_2(ctx);
}
static duk_ret_t duk__handle_require(duk_context *ctx) {
/*
* Value stack handling here is a bit sloppy but should be correct.
* Call handling will clean up any extra garbage for us.
*/
const char *id;
const char *parent_id;
duk_idx_t module_idx;
duk_idx_t stash_idx;
duk_int_t ret;
duk_push_global_stash(ctx);
stash_idx = duk_normalize_index(ctx, -1);
duk_push_current_function(ctx);
(void) duk_get_prop_string(ctx, -1, "\xff" "moduleId");
parent_id = duk_require_string(ctx, -1);
(void) parent_id; /* not used directly; suppress warning */
/* [ id stash require parent_id ] */
id = duk_require_string(ctx, 0);
(void) duk_get_prop_string(ctx, stash_idx, "\xff" "modResolve");
duk_dup(ctx, 0); /* module ID */
duk_dup(ctx, -3); /* parent ID */
duk_call(ctx, 2);
/* [ ... stash ... resolved_id ] */
id = duk_require_string(ctx, -1);
if (duk__get_cached_module(ctx, id)) {
goto have_module; /* use the cached module */
}
duk__push_module_object(ctx, id, 0 /*main*/);
duk__put_cached_module(ctx); /* module remains on stack */
/*
* From here on out, we have to be careful not to throw. If it can't be
* avoided, the error must be caught and the module removed from the
* require cache before rethrowing. This allows the application to
* reattempt loading the module.
*/
module_idx = duk_normalize_index(ctx, -1);
/* [ ... stash ... resolved_id module ] */
(void) duk_get_prop_string(ctx, stash_idx, "\xff" "modLoad");
duk_dup(ctx, -3); /* resolved ID */
(void) duk_get_prop_string(ctx, module_idx, "exports");
duk_dup(ctx, module_idx);
ret = duk_pcall(ctx, 3);
if (ret != DUK_EXEC_SUCCESS) {
duk__del_cached_module(ctx, id);
(void) duk_throw(ctx); /* rethrow */
}
if (duk_is_string(ctx, -1)) {
duk_int_t ret;
/* [ ... module source ] */
#if DUK_VERSION >= 19999
ret = duk_safe_call(ctx, duk__eval_module_source, NULL, 2, 1);
#else
ret = duk_safe_call(ctx, duk__eval_module_source, 2, 1);
#endif
if (ret != DUK_EXEC_SUCCESS) {
duk__del_cached_module(ctx, id);
(void) duk_throw(ctx); /* rethrow */
}
} else if (duk_is_undefined(ctx, -1)) {
duk_pop(ctx);
} else {
duk__del_cached_module(ctx, id);
(void) duk_type_error(ctx, "invalid module load callback return value");
}
/* fall through */
have_module:
/* [ ... module ] */
(void) duk_get_prop_string(ctx, -1, "exports");
return 1;
}
static void duk__push_require_function(duk_context *ctx, const char *id) {
duk_push_c_function(ctx, duk__handle_require, 1);
duk_push_string(ctx, "name");
duk_push_string(ctx, "require");
duk_def_prop(ctx, -3, DUK_DEFPROP_HAVE_VALUE);
duk_push_string(ctx, id);
duk_put_prop_string(ctx, -2, "\xff" "moduleId");
/* require.cache */
duk_push_global_stash(ctx);
(void) duk_get_prop_string(ctx, -1, "\xff" "requireCache");
duk_put_prop_string(ctx, -3, "cache");
duk_pop(ctx);
/* require.main */
duk_push_global_stash(ctx);
(void) duk_get_prop_string(ctx, -1, "\xff" "mainModule");
duk_put_prop_string(ctx, -3, "main");
duk_pop(ctx);
}
static void duk__push_module_object(duk_context *ctx, const char *id, duk_bool_t main) {
duk_push_object(ctx);
/* Set this as the main module, if requested */
if (main) {
duk_push_global_stash(ctx);
duk_dup(ctx, -2);
duk_put_prop_string(ctx, -2, "\xff" "mainModule");
duk_pop(ctx);
}
/* Node.js uses the canonicalized filename of a module for both module.id
* and module.filename. We have no concept of a file system here, so just
* use the module ID for both values.
*/
duk_push_string(ctx, id);
duk_dup(ctx, -1);
duk_put_prop_string(ctx, -3, "filename");
duk_put_prop_string(ctx, -2, "id");
/* module.exports = {} */
duk_push_object(ctx);
duk_put_prop_string(ctx, -2, "exports");
/* module.loaded = false */
duk_push_false(ctx);
duk_put_prop_string(ctx, -2, "loaded");
/* module.require */
duk__push_require_function(ctx, id);
duk_put_prop_string(ctx, -2, "require");
}
#if DUK_VERSION >= 19999
static duk_int_t duk__eval_module_source(duk_context *ctx, void *udata) {
#else
static duk_int_t duk__eval_module_source(duk_context *ctx) {
#endif
const char *src;
/*
* Stack: [ ... module source ]
*/
#if DUK_VERSION >= 19999
(void) udata;
#endif
/* Wrap the module code in a function expression. This is the simplest
* way to implement CommonJS closure semantics and matches the behavior of
* e.g. Node.js.
*/
duk_push_string(ctx, "(function(exports,require,module,__filename,__dirname){");
src = duk_require_string(ctx, -2);
duk_push_string(ctx, (src[0] == '#' && src[1] == '!') ? "//" : ""); /* Shebang support. */
duk_dup(ctx, -3); /* source */
duk_push_string(ctx, "\n})"); /* Newline allows module last line to contain a // comment. */
duk_concat(ctx, 4);
/* [ ... module source func_src ] */
(void) duk_get_prop_string(ctx, -3, "filename");
duk_compile(ctx, DUK_COMPILE_EVAL);
duk_call(ctx, 0);
/* [ ... module source func ] */
/* Set name for the wrapper function. */
duk_push_string(ctx, "name");
duk_push_string(ctx, "main");
duk_def_prop(ctx, -3, DUK_DEFPROP_HAVE_VALUE | DUK_DEFPROP_FORCE);
/* call the function wrapper */
(void) duk_get_prop_string(ctx, -3, "exports"); /* exports */
(void) duk_get_prop_string(ctx, -4, "require"); /* require */
duk_dup(ctx, -5); /* module */
(void) duk_get_prop_string(ctx, -6, "filename"); /* __filename */
duk_push_undefined(ctx); /* __dirname */
duk_call(ctx, 5);
/* [ ... module source result(ignore) ] */
/* module.loaded = true */
duk_push_true(ctx);
duk_put_prop_string(ctx, -4, "loaded");
/* [ ... module source retval ] */
duk_pop_2(ctx);
/* [ ... module ] */
return 1;
}
/* Load a module as the 'main' module. */
duk_ret_t duk_module_node_peval_main(duk_context *ctx, const char *path) {
/*
* Stack: [ ... source ]
*/
duk__push_module_object(ctx, path, 1 /*main*/);
/* [ ... source module ] */
duk_dup(ctx, 0);
/* [ ... source module source ] */
#if DUK_VERSION >= 19999
return duk_safe_call(ctx, duk__eval_module_source, NULL, 2, 1);
#else
return duk_safe_call(ctx, duk__eval_module_source, 2, 1);
#endif
}
void duk_module_node_init(duk_context *ctx) {
/*
* Stack: [ ... options ] => [ ... ]
*/
duk_idx_t options_idx;
duk_require_object_coercible(ctx, -1); /* error before setting up requireCache */
options_idx = duk_require_normalize_index(ctx, -1);
/* Initialize the require cache to a fresh object. */
duk_push_global_stash(ctx);
#if DUK_VERSION >= 19999
duk_push_bare_object(ctx);
#else
duk_push_object(ctx);
duk_push_undefined(ctx);
duk_set_prototype(ctx, -2);
#endif
duk_put_prop_string(ctx, -2, "\xff" "requireCache");
duk_pop(ctx);
/* Stash callbacks for later use. User code can overwrite them later
* on directly by accessing the global stash.
*/
duk_push_global_stash(ctx);
duk_get_prop_string(ctx, options_idx, "resolve");
duk_require_function(ctx, -1);
duk_put_prop_string(ctx, -2, "\xff" "modResolve");
duk_get_prop_string(ctx, options_idx, "load");
duk_require_function(ctx, -1);
duk_put_prop_string(ctx, -2, "\xff" "modLoad");
duk_pop(ctx);
/* Stash main module. */
duk_push_global_stash(ctx);
duk_push_undefined(ctx);
duk_put_prop_string(ctx, -2, "\xff" "mainModule");
duk_pop(ctx);
/* register `require` as a global function. */
duk_push_global_object(ctx);
duk_push_string(ctx, "require");
duk__push_require_function(ctx, "");
duk_def_prop(ctx, -3, DUK_DEFPROP_HAVE_VALUE |
DUK_DEFPROP_SET_WRITABLE |
DUK_DEFPROP_SET_CONFIGURABLE);
duk_pop(ctx);
duk_pop(ctx); /* pop argument */
}
