472 lines
17 KiB
C
472 lines
17 KiB
C
/*
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* Duktape 1.x compatible module loading framework
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*/
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#include "duktape.h"
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#include "duk_module_duktape.h"
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/* (v)snprintf() is missing before MSVC 2015. Note that _(v)snprintf() does
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* NOT NUL terminate on truncation, but that's OK here.
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* http://stackoverflow.com/questions/2915672/snprintf-and-visual-studio-2010
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*/
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#if defined(_MSC_VER) && (_MSC_VER < 1900)
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#define snprintf _snprintf
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#endif
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#if 0 /* Enable manually */
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#define DUK__ASSERT(x) do { \
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if (!(x)) { \
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fprintf(stderr, "ASSERTION FAILED at %s:%d: " #x "\n", __FILE__, __LINE__); \
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fflush(stderr); \
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} \
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} while (0)
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#define DUK__ASSERT_TOP(ctx,val) do { \
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DUK__ASSERT(duk_get_top((ctx)) == (val)); \
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} while (0)
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#else
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#define DUK__ASSERT(x) do { (void) (x); } while (0)
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#define DUK__ASSERT_TOP(ctx,val) do { (void) ctx; (void) (val); } while (0)
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#endif
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static void duk__resolve_module_id(duk_context *ctx, const char *req_id, const char *mod_id) {
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duk_uint8_t buf[DUK_COMMONJS_MODULE_ID_LIMIT];
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duk_uint8_t *p;
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duk_uint8_t *q;
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duk_uint8_t *q_last; /* last component */
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duk_int_t int_rc;
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DUK__ASSERT(req_id != NULL);
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/* mod_id may be NULL */
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/*
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* A few notes on the algorithm:
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*
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* - Terms are not allowed to begin with a period unless the term
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* is either '.' or '..'. This simplifies implementation (and
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* is within CommonJS modules specification).
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*
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* - There are few output bound checks here. This is on purpose:
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* the resolution input is length checked and the output is never
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* longer than the input. The resolved output is written directly
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* over the input because it's never longer than the input at any
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* point in the algorithm.
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*
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* - Non-ASCII characters are processed as individual bytes and
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* need no special treatment. However, U+0000 terminates the
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* algorithm; this is not an issue because U+0000 is not a
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* desirable term character anyway.
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*/
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/*
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* Set up the resolution input which is the requested ID directly
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* (if absolute or no current module path) or with current module
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* ID prepended (if relative and current module path exists).
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*
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* Suppose current module is 'foo/bar' and relative path is './quux'.
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* The 'bar' component must be replaced so the initial input here is
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* 'foo/bar/.././quux'.
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*/
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if (mod_id != NULL && req_id[0] == '.') {
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int_rc = snprintf((char *) buf, sizeof(buf), "%s/../%s", mod_id, req_id);
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} else {
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int_rc = snprintf((char *) buf, sizeof(buf), "%s", req_id);
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}
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if (int_rc >= (duk_int_t) sizeof(buf) || int_rc < 0) {
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/* Potentially truncated, NUL not guaranteed in any case.
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* The (int_rc < 0) case should not occur in practice.
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*/
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goto resolve_error;
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}
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DUK__ASSERT(strlen((const char *) buf) < sizeof(buf)); /* at most sizeof(buf) - 1 */
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/*
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* Resolution loop. At the top of the loop we're expecting a valid
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* term: '.', '..', or a non-empty identifier not starting with a period.
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*/
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p = buf;
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q = buf;
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for (;;) {
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duk_uint_fast8_t c;
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/* Here 'p' always points to the start of a term.
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*
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* We can also unconditionally reset q_last here: if this is
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* the last (non-empty) term q_last will have the right value
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* on loop exit.
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*/
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DUK__ASSERT(p >= q); /* output is never longer than input during resolution */
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q_last = q;
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c = *p++;
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if (c == 0) {
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goto resolve_error;
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} else if (c == '.') {
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c = *p++;
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if (c == '/') {
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/* Term was '.' and is eaten entirely (including dup slashes). */
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goto eat_dup_slashes;
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}
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if (c == '.' && *p == '/') {
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/* Term was '..', backtrack resolved name by one component.
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* q[-1] = previous slash (or beyond start of buffer)
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* q[-2] = last char of previous component (or beyond start of buffer)
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*/
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p++; /* eat (first) input slash */
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DUK__ASSERT(q >= buf);
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if (q == buf) {
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goto resolve_error;
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}
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DUK__ASSERT(*(q - 1) == '/');
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q--; /* Backtrack to last output slash (dups already eliminated). */
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for (;;) {
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/* Backtrack to previous slash or start of buffer. */
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DUK__ASSERT(q >= buf);
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if (q == buf) {
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break;
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}
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if (*(q - 1) == '/') {
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break;
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}
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q--;
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}
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goto eat_dup_slashes;
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}
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goto resolve_error;
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} else if (c == '/') {
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/* e.g. require('/foo'), empty terms not allowed */
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goto resolve_error;
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} else {
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for (;;) {
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/* Copy term name until end or '/'. */
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*q++ = c;
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c = *p++;
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if (c == 0) {
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/* This was the last term, and q_last was
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* updated to match this term at loop top.
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*/
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goto loop_done;
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} else if (c == '/') {
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*q++ = '/';
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break;
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} else {
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/* write on next loop */
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}
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}
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}
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eat_dup_slashes:
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for (;;) {
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/* eat dup slashes */
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c = *p;
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if (c != '/') {
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break;
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}
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p++;
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}
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}
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loop_done:
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/* Output #1: resolved absolute name. */
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DUK__ASSERT(q >= buf);
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duk_push_lstring(ctx, (const char *) buf, (size_t) (q - buf));
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/* Output #2: last component name. */
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DUK__ASSERT(q >= q_last);
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DUK__ASSERT(q_last >= buf);
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duk_push_lstring(ctx, (const char *) q_last, (size_t) (q - q_last));
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return;
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resolve_error:
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(void) duk_type_error(ctx, "cannot resolve module id: %s", (const char *) req_id);
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}
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/* Stack indices for better readability. */
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#define DUK__IDX_REQUESTED_ID 0 /* module id requested */
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#define DUK__IDX_REQUIRE 1 /* current require() function */
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#define DUK__IDX_REQUIRE_ID 2 /* the base ID of the current require() function, resolution base */
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#define DUK__IDX_RESOLVED_ID 3 /* resolved, normalized absolute module ID */
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#define DUK__IDX_LASTCOMP 4 /* last component name in resolved path */
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#define DUK__IDX_DUKTAPE 5 /* Duktape object */
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#define DUK__IDX_MODLOADED 6 /* Duktape.modLoaded[] module cache */
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#define DUK__IDX_UNDEFINED 7 /* 'undefined', artifact of lookup */
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#define DUK__IDX_FRESH_REQUIRE 8 /* new require() function for module, updated resolution base */
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#define DUK__IDX_EXPORTS 9 /* default exports table */
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#define DUK__IDX_MODULE 10 /* module object containing module.exports, etc */
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static duk_ret_t duk__require(duk_context *ctx) {
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const char *str_req_id; /* requested identifier */
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const char *str_mod_id; /* require.id of current module */
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duk_int_t pcall_rc;
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/* NOTE: we try to minimize code size by avoiding unnecessary pops,
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* so the stack looks a bit cluttered in this function. DUK__ASSERT_TOP()
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* assertions are used to ensure stack configuration is correct at each
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* step.
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*/
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/*
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* Resolve module identifier into canonical absolute form.
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*/
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str_req_id = duk_require_string(ctx, DUK__IDX_REQUESTED_ID);
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duk_push_current_function(ctx);
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duk_get_prop_string(ctx, -1, "id");
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str_mod_id = duk_get_string(ctx, DUK__IDX_REQUIRE_ID); /* ignore non-strings */
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duk__resolve_module_id(ctx, str_req_id, str_mod_id);
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str_req_id = NULL;
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str_mod_id = NULL;
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/* [ requested_id require require.id resolved_id last_comp ] */
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DUK__ASSERT_TOP(ctx, DUK__IDX_LASTCOMP + 1);
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/*
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* Cached module check.
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*
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* If module has been loaded or its loading has already begun without
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* finishing, return the same cached value (module.exports). The
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* value is registered when module load starts so that circular
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* references can be supported to some extent.
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*/
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duk_push_global_stash(ctx);
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duk_get_prop_string(ctx, -1, "\xff" "module:Duktape");
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duk_remove(ctx, -2); /* Lookup stashed, original 'Duktape' object. */
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duk_get_prop_string(ctx, DUK__IDX_DUKTAPE, "modLoaded"); /* Duktape.modLoaded */
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duk_require_type_mask(ctx, DUK__IDX_MODLOADED, DUK_TYPE_MASK_OBJECT);
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DUK__ASSERT_TOP(ctx, DUK__IDX_MODLOADED + 1);
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duk_dup(ctx, DUK__IDX_RESOLVED_ID);
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if (duk_get_prop(ctx, DUK__IDX_MODLOADED)) {
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/* [ requested_id require require.id resolved_id last_comp Duktape Duktape.modLoaded Duktape.modLoaded[id] ] */
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duk_get_prop_string(ctx, -1, "exports"); /* return module.exports */
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return 1;
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}
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DUK__ASSERT_TOP(ctx, DUK__IDX_UNDEFINED + 1);
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/* [ requested_id require require.id resolved_id last_comp Duktape Duktape.modLoaded undefined ] */
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/*
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* Module not loaded (and loading not started previously).
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*
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* Create a new require() function with 'id' set to resolved ID
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* of module being loaded. Also create 'exports' and 'module'
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* tables but don't register exports to the loaded table yet.
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* We don't want to do that unless the user module search callbacks
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* succeeds in finding the module.
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*/
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/* Fresh require: require.id is left configurable (but not writable)
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* so that is not easy to accidentally tweak it, but it can still be
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* done with Object.defineProperty().
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*
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* XXX: require.id could also be just made non-configurable, as there
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* is no practical reason to touch it (at least from ECMAScript code).
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*/
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duk_push_c_function(ctx, duk__require, 1 /*nargs*/);
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duk_push_string(ctx, "name");
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duk_push_string(ctx, "require");
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duk_def_prop(ctx, DUK__IDX_FRESH_REQUIRE, DUK_DEFPROP_HAVE_VALUE); /* not writable, not enumerable, not configurable */
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duk_push_string(ctx, "id");
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duk_dup(ctx, DUK__IDX_RESOLVED_ID);
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duk_def_prop(ctx, DUK__IDX_FRESH_REQUIRE, DUK_DEFPROP_HAVE_VALUE | DUK_DEFPROP_SET_CONFIGURABLE); /* a fresh require() with require.id = resolved target module id */
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/* Module table:
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* - module.exports: initial exports table (may be replaced by user)
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* - module.id is non-writable and non-configurable, as the CommonJS
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* spec suggests this if possible
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* - module.filename: not set, defaults to resolved ID if not explicitly
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* set by modSearch() (note capitalization, not .fileName, matches Node.js)
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* - module.name: not set, defaults to last component of resolved ID if
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* not explicitly set by modSearch()
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*/
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duk_push_object(ctx); /* exports */
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duk_push_object(ctx); /* module */
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duk_push_string(ctx, "exports");
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duk_dup(ctx, DUK__IDX_EXPORTS);
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duk_def_prop(ctx, DUK__IDX_MODULE, DUK_DEFPROP_HAVE_VALUE | DUK_DEFPROP_SET_WRITABLE | DUK_DEFPROP_SET_CONFIGURABLE); /* module.exports = exports */
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duk_push_string(ctx, "id");
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duk_dup(ctx, DUK__IDX_RESOLVED_ID); /* resolved id: require(id) must return this same module */
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duk_def_prop(ctx, DUK__IDX_MODULE, DUK_DEFPROP_HAVE_VALUE); /* module.id = resolved_id; not writable, not enumerable, not configurable */
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duk_compact(ctx, DUK__IDX_MODULE); /* module table remains registered to modLoaded, minimize its size */
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DUK__ASSERT_TOP(ctx, DUK__IDX_MODULE + 1);
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/* [ requested_id require require.id resolved_id last_comp Duktape Duktape.modLoaded undefined fresh_require exports module ] */
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/* Register the module table early to modLoaded[] so that we can
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* support circular references even in modSearch(). If an error
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* is thrown, we'll delete the reference.
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*/
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duk_dup(ctx, DUK__IDX_RESOLVED_ID);
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duk_dup(ctx, DUK__IDX_MODULE);
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duk_put_prop(ctx, DUK__IDX_MODLOADED); /* Duktape.modLoaded[resolved_id] = module */
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/*
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* Call user provided module search function and build the wrapped
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* module source code (if necessary). The module search function
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* can be used to implement pure Ecmacsript, pure C, and mixed
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* ECMAScript/C modules.
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*
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* The module search function can operate on the exports table directly
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* (e.g. DLL code can register values to it). It can also return a
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* string which is interpreted as module source code (if a non-string
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* is returned the module is assumed to be a pure C one). If a module
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* cannot be found, an error must be thrown by the user callback.
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*
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* Because Duktape.modLoaded[] already contains the module being
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* loaded, circular references for C modules should also work
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* (although expected to be quite rare).
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*/
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duk_push_string(ctx, "(function(require,exports,module){");
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/* Duktape.modSearch(resolved_id, fresh_require, exports, module). */
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duk_get_prop_string(ctx, DUK__IDX_DUKTAPE, "modSearch"); /* Duktape.modSearch */
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duk_dup(ctx, DUK__IDX_RESOLVED_ID);
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duk_dup(ctx, DUK__IDX_FRESH_REQUIRE);
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duk_dup(ctx, DUK__IDX_EXPORTS);
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duk_dup(ctx, DUK__IDX_MODULE); /* [ ... Duktape.modSearch resolved_id last_comp fresh_require exports module ] */
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pcall_rc = duk_pcall(ctx, 4 /*nargs*/); /* -> [ ... source ] */
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DUK__ASSERT_TOP(ctx, DUK__IDX_MODULE + 3);
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if (pcall_rc != DUK_EXEC_SUCCESS) {
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/* Delete entry in Duktape.modLoaded[] and rethrow. */
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goto delete_rethrow;
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}
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/* If user callback did not return source code, module loading
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* is finished (user callback initialized exports table directly).
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*/
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if (!duk_is_string(ctx, -1)) {
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/* User callback did not return source code, so module loading
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* is finished: just update modLoaded with final module.exports
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* and we're done.
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*/
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goto return_exports;
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}
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/* Finish the wrapped module source. Force module.filename as the
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* function .fileName so it gets set for functions defined within a
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* module. This also ensures loggers created within the module get
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* the module ID (or overridden filename) as their default logger name.
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* (Note capitalization: .filename matches Node.js while .fileName is
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* used elsewhere in Duktape.)
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*/
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duk_push_string(ctx, "\n})"); /* Newline allows module last line to contain a // comment. */
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duk_concat(ctx, 3);
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if (!duk_get_prop_string(ctx, DUK__IDX_MODULE, "filename")) {
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/* module.filename for .fileName, default to resolved ID if
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* not present.
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*/
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duk_pop(ctx);
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duk_dup(ctx, DUK__IDX_RESOLVED_ID);
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}
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pcall_rc = duk_pcompile(ctx, DUK_COMPILE_EVAL);
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if (pcall_rc != DUK_EXEC_SUCCESS) {
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goto delete_rethrow;
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}
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pcall_rc = duk_pcall(ctx, 0); /* -> eval'd function wrapper (not called yet) */
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if (pcall_rc != DUK_EXEC_SUCCESS) {
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goto delete_rethrow;
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}
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/* Module has now evaluated to a wrapped module function. Force its
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* .name to match module.name (defaults to last component of resolved
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* ID) so that it is shown in stack traces too. Note that we must not
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* introduce an actual name binding into the function scope (which is
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* usually the case with a named function) because it would affect the
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* scope seen by the module and shadow accesses to globals of the same name.
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* This is now done by compiling the function as anonymous and then forcing
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* its .name without setting a "has name binding" flag.
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*/
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duk_push_string(ctx, "name");
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if (!duk_get_prop_string(ctx, DUK__IDX_MODULE, "name")) {
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/* module.name for .name, default to last component if
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* not present.
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*/
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duk_pop(ctx);
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duk_dup(ctx, DUK__IDX_LASTCOMP);
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}
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duk_def_prop(ctx, -3, DUK_DEFPROP_HAVE_VALUE | DUK_DEFPROP_FORCE);
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/*
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* Call the wrapped module function.
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*
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* Use a protected call so that we can update Duktape.modLoaded[resolved_id]
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* even if the module throws an error.
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*/
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/* [ requested_id require require.id resolved_id last_comp Duktape Duktape.modLoaded undefined fresh_require exports module mod_func ] */
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DUK__ASSERT_TOP(ctx, DUK__IDX_MODULE + 2);
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duk_dup(ctx, DUK__IDX_EXPORTS); /* exports (this binding) */
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duk_dup(ctx, DUK__IDX_FRESH_REQUIRE); /* fresh require (argument) */
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duk_get_prop_string(ctx, DUK__IDX_MODULE, "exports"); /* relookup exports from module.exports in case it was changed by modSearch */
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duk_dup(ctx, DUK__IDX_MODULE); /* module (argument) */
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DUK__ASSERT_TOP(ctx, DUK__IDX_MODULE + 6);
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/* [ requested_id require require.id resolved_id last_comp Duktape Duktape.modLoaded undefined fresh_require exports module mod_func exports fresh_require exports module ] */
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pcall_rc = duk_pcall_method(ctx, 3 /*nargs*/);
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if (pcall_rc != DUK_EXEC_SUCCESS) {
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/* Module loading failed. Node.js will forget the module
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* registration so that another require() will try to load
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* the module again. Mimic that behavior.
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*/
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goto delete_rethrow;
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}
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/* [ requested_id require require.id resolved_id last_comp Duktape Duktape.modLoaded undefined fresh_require exports module result(ignored) ] */
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DUK__ASSERT_TOP(ctx, DUK__IDX_MODULE + 2);
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/* fall through */
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return_exports:
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duk_get_prop_string(ctx, DUK__IDX_MODULE, "exports");
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duk_compact(ctx, -1); /* compact the exports table */
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return 1; /* return module.exports */
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delete_rethrow:
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duk_dup(ctx, DUK__IDX_RESOLVED_ID);
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duk_del_prop(ctx, DUK__IDX_MODLOADED); /* delete Duktape.modLoaded[resolved_id] */
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(void) duk_throw(ctx); /* rethrow original error */
|
|
return 0; /* not reachable */
|
|
}
|
|
|
|
void duk_module_duktape_init(duk_context *ctx) {
|
|
/* Stash 'Duktape' in case it's modified. */
|
|
duk_push_global_stash(ctx);
|
|
duk_get_global_string(ctx, "Duktape");
|
|
duk_put_prop_string(ctx, -2, "\xff" "module:Duktape");
|
|
duk_pop(ctx);
|
|
|
|
/* Register `require` as a global function. */
|
|
duk_eval_string(ctx,
|
|
"(function(req){"
|
|
"var D=Object.defineProperty;"
|
|
"D(req,'name',{value:'require'});"
|
|
"D(this,'require',{value:req,writable:true,configurable:true});"
|
|
"D(Duktape,'modLoaded',{value:Object.create(null),writable:true,configurable:true});"
|
|
"})");
|
|
duk_push_c_function(ctx, duk__require, 1 /*nargs*/);
|
|
duk_call(ctx, 1);
|
|
duk_pop(ctx);
|
|
}
|
|
|
|
#undef DUK__ASSERT
|
|
#undef DUK__ASSERT_TOP
|
|
#undef DUK__IDX_REQUESTED_ID
|
|
#undef DUK__IDX_REQUIRE
|
|
#undef DUK__IDX_REQUIRE_ID
|
|
#undef DUK__IDX_RESOLVED_ID
|
|
#undef DUK__IDX_LASTCOMP
|
|
#undef DUK__IDX_DUKTAPE
|
|
#undef DUK__IDX_MODLOADED
|
|
#undef DUK__IDX_UNDEFINED
|
|
#undef DUK__IDX_FRESH_REQUIRE
|
|
#undef DUK__IDX_EXPORTS
|
|
#undef DUK__IDX_MODULE
|