duktape-1.5.2/src-separate/duk_bi_global.c

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/*
 *  Global object built-ins
 */
 
#include "duk_internal.h"
 
/*
 *  Encoding/decoding helpers
 */
 
/* XXX: Could add fast path (for each transform callback) with direct byte
 * lookups (no shifting) and no explicit check for x < 0x80 before table
 * lookup.
 */
 
/* Macros for creating and checking bitmasks for character encoding.
 * Bit number is a bit counterintuitive, but minimizes code size.
 */
#define DUK__MKBITS(a,b,c,d,e,f,g,h)  ((duk_uint8_t) ( \
    ((a) << 0) | ((b) << 1) | ((c) << 2) | ((d) << 3) | \
    ((e) << 4) | ((f) << 5) | ((g) << 6) | ((h) << 7) \
    ))
#define DUK__CHECK_BITMASK(table,cp)  ((table)[(cp) >> 3] & (1 << ((cp) & 0x07)))
 
/* E5.1 Section 15.1.3.3: uriReserved + uriUnescaped + '#' */
DUK_LOCAL const duk_uint8_t duk__encode_uriunescaped_table[16] = {
    DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0), DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0),  /* 0x00-0x0f */
    DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0), DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0),  /* 0x10-0x1f */
    DUK__MKBITS(0, 1, 0, 1, 1, 0, 1, 1), DUK__MKBITS(1, 1, 1, 1, 1, 1, 1, 1),  /* 0x20-0x2f */
    DUK__MKBITS(1, 1, 1, 1, 1, 1, 1, 1), DUK__MKBITS(1, 1, 1, 1, 0, 1, 0, 1),  /* 0x30-0x3f */
    DUK__MKBITS(1, 1, 1, 1, 1, 1, 1, 1), DUK__MKBITS(1, 1, 1, 1, 1, 1, 1, 1),  /* 0x40-0x4f */
    DUK__MKBITS(1, 1, 1, 1, 1, 1, 1, 1), DUK__MKBITS(1, 1, 1, 0, 0, 0, 0, 1),  /* 0x50-0x5f */
    DUK__MKBITS(0, 1, 1, 1, 1, 1, 1, 1), DUK__MKBITS(1, 1, 1, 1, 1, 1, 1, 1),  /* 0x60-0x6f */
    DUK__MKBITS(1, 1, 1, 1, 1, 1, 1, 1), DUK__MKBITS(1, 1, 1, 0, 0, 0, 1, 0),  /* 0x70-0x7f */
};
 
/* E5.1 Section 15.1.3.4: uriUnescaped */
DUK_LOCAL const duk_uint8_t duk__encode_uricomponent_unescaped_table[16] = {
    DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0), DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0),  /* 0x00-0x0f */
    DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0), DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0),  /* 0x10-0x1f */
    DUK__MKBITS(0, 1, 0, 0, 0, 0, 0, 1), DUK__MKBITS(1, 1, 1, 0, 0, 1, 1, 0),  /* 0x20-0x2f */
    DUK__MKBITS(1, 1, 1, 1, 1, 1, 1, 1), DUK__MKBITS(1, 1, 0, 0, 0, 0, 0, 0),  /* 0x30-0x3f */
    DUK__MKBITS(0, 1, 1, 1, 1, 1, 1, 1), DUK__MKBITS(1, 1, 1, 1, 1, 1, 1, 1),  /* 0x40-0x4f */
    DUK__MKBITS(1, 1, 1, 1, 1, 1, 1, 1), DUK__MKBITS(1, 1, 1, 0, 0, 0, 0, 1),  /* 0x50-0x5f */
    DUK__MKBITS(0, 1, 1, 1, 1, 1, 1, 1), DUK__MKBITS(1, 1, 1, 1, 1, 1, 1, 1),  /* 0x60-0x6f */
    DUK__MKBITS(1, 1, 1, 1, 1, 1, 1, 1), DUK__MKBITS(1, 1, 1, 0, 0, 0, 1, 0),  /* 0x70-0x7f */
};
 
/* E5.1 Section 15.1.3.1: uriReserved + '#' */
DUK_LOCAL const duk_uint8_t duk__decode_uri_reserved_table[16] = {
    DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0), DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0),  /* 0x00-0x0f */
    DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0), DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0),  /* 0x10-0x1f */
    DUK__MKBITS(0, 0, 0, 1, 1, 0, 1, 0), DUK__MKBITS(0, 0, 0, 1, 1, 0, 0, 1),  /* 0x20-0x2f */
    DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0), DUK__MKBITS(0, 0, 1, 1, 0, 1, 0, 1),  /* 0x30-0x3f */
    DUK__MKBITS(1, 0, 0, 0, 0, 0, 0, 0), DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0),  /* 0x40-0x4f */
    DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0), DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0),  /* 0x50-0x5f */
    DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0), DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0),  /* 0x60-0x6f */
    DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0), DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0),  /* 0x70-0x7f */
};
 
/* E5.1 Section 15.1.3.2: empty */
DUK_LOCAL const duk_uint8_t duk__decode_uri_component_reserved_table[16] = {
    DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0), DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0),  /* 0x00-0x0f */
    DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0), DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0),  /* 0x10-0x1f */
    DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0), DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0),  /* 0x20-0x2f */
    DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0), DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0),  /* 0x30-0x3f */
    DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0), DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0),  /* 0x40-0x4f */
    DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0), DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0),  /* 0x50-0x5f */
    DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0), DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0),  /* 0x60-0x6f */
    DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0), DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0),  /* 0x70-0x7f */
};
 
#ifdef DUK_USE_SECTION_B
/* E5.1 Section B.2.2, step 7. */
DUK_LOCAL const duk_uint8_t duk__escape_unescaped_table[16] = {
    DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0), DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0),  /* 0x00-0x0f */
    DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0), DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0),  /* 0x10-0x1f */
    DUK__MKBITS(0, 0, 0, 0, 0, 0, 0, 0), DUK__MKBITS(0, 0, 1, 1, 0, 1, 1, 1),  /* 0x20-0x2f */
    DUK__MKBITS(1, 1, 1, 1, 1, 1, 1, 1), DUK__MKBITS(1, 1, 0, 0, 0, 0, 0, 0),  /* 0x30-0x3f */
    DUK__MKBITS(1, 1, 1, 1, 1, 1, 1, 1), DUK__MKBITS(1, 1, 1, 1, 1, 1, 1, 1),  /* 0x40-0x4f */
    DUK__MKBITS(1, 1, 1, 1, 1, 1, 1, 1), DUK__MKBITS(1, 1, 1, 0, 0, 0, 0, 1),  /* 0x50-0x5f */
    DUK__MKBITS(0, 1, 1, 1, 1, 1, 1, 1), DUK__MKBITS(1, 1, 1, 1, 1, 1, 1, 1),  /* 0x60-0x6f */
    DUK__MKBITS(1, 1, 1, 1, 1, 1, 1, 1), DUK__MKBITS(1, 1, 1, 0, 0, 0, 0, 0)   /* 0x70-0x7f */
};
#endif  /* DUK_USE_SECTION_B */
 
#undef DUK__MKBITS
 
typedef struct {
    duk_hthread *thr;
    duk_hstring *h_str;
    duk_bufwriter_ctx bw;
    const duk_uint8_t *p;
    const duk_uint8_t *p_start;
    const duk_uint8_t *p_end;
} duk__transform_context;
 
typedef void (*duk__transform_callback)(duk__transform_context *tfm_ctx, const void *udata, duk_codepoint_t cp);
 
/* XXX: refactor and share with other code */
DUK_LOCAL duk_small_int_t duk__decode_hex_escape(const duk_uint8_t *p, duk_small_int_t n) {
    duk_small_int_t ch;
    duk_small_int_t t = 0;
 
    while (n > 0) {
        t = t * 16;
        ch = (duk_small_int_t) duk_hex_dectab[*p++];
        if (DUK_LIKELY(ch >= 0)) {
            t += ch;
        } else {
            return -1;
        }
        n--;
    }
    return t;
}
 
DUK_LOCAL int duk__transform_helper(duk_context *ctx, duk__transform_callback callback, const void *udata) {
    duk_hthread *thr = (duk_hthread *) ctx;
    duk__transform_context tfm_ctx_alloc;
    duk__transform_context *tfm_ctx = &tfm_ctx_alloc;
    duk_codepoint_t cp;
 
    tfm_ctx->thr = thr;
 
    tfm_ctx->h_str = duk_to_hstring(ctx, 0);
    DUK_ASSERT(tfm_ctx->h_str != NULL);
 
    DUK_BW_INIT_PUSHBUF(thr, &tfm_ctx->bw, DUK_HSTRING_GET_BYTELEN(tfm_ctx->h_str));  /* initial size guess */
 
    tfm_ctx->p_start = DUK_HSTRING_GET_DATA(tfm_ctx->h_str);
    tfm_ctx->p_end = tfm_ctx->p_start + DUK_HSTRING_GET_BYTELEN(tfm_ctx->h_str);
    tfm_ctx->p = tfm_ctx->p_start;
 
    while (tfm_ctx->p < tfm_ctx->p_end) {
        cp = (duk_codepoint_t) duk_unicode_decode_xutf8_checked(thr, &tfm_ctx->p, tfm_ctx->p_start, tfm_ctx->p_end);
        callback(tfm_ctx, udata, cp);
    }
 
    DUK_BW_COMPACT(thr, &tfm_ctx->bw);
 
    duk_to_string(ctx, -1);
    return 1;
}
 
DUK_LOCAL void duk__transform_callback_encode_uri(duk__transform_context *tfm_ctx, const void *udata, duk_codepoint_t cp) {
    duk_uint8_t xutf8_buf[DUK_UNICODE_MAX_XUTF8_LENGTH];
    duk_small_int_t len;
    duk_codepoint_t cp1, cp2;
    duk_small_int_t i, t;
    const duk_uint8_t *unescaped_table = (const duk_uint8_t *) udata;
 
    /* UTF-8 encoded bytes escaped as %xx%xx%xx... -> 3 * nbytes.
     * Codepoint range is restricted so this is a slightly too large
     * but doesn't matter.
     */
    DUK_BW_ENSURE(tfm_ctx->thr, &tfm_ctx->bw, 3 * DUK_UNICODE_MAX_XUTF8_LENGTH);
 
    if (cp < 0) {
        goto uri_error;
    } else if ((cp < 0x80L) && DUK__CHECK_BITMASK(unescaped_table, cp)) {
        DUK_BW_WRITE_RAW_U8(tfm_ctx->thr, &tfm_ctx->bw, (duk_uint8_t) cp);
        return;
    } else if (cp >= 0xdc00L && cp <= 0xdfffL) {
        goto uri_error;
    } else if (cp >= 0xd800L && cp <= 0xdbffL) {
        /* Needs lookahead */
        if (duk_unicode_decode_xutf8(tfm_ctx->thr, &tfm_ctx->p, tfm_ctx->p_start, tfm_ctx->p_end, (duk_ucodepoint_t *) &cp2) == 0) {
            goto uri_error;
        }
        if (!(cp2 >= 0xdc00L && cp2 <= 0xdfffL)) {
            goto uri_error;
        }
        cp1 = cp;
        cp = ((cp1 - 0xd800L) << 10) + (cp2 - 0xdc00L) + 0x10000L;
    } else if (cp > 0x10ffffL) {
        /* Although we can allow non-BMP characters (they'll decode
         * back into surrogate pairs), we don't allow extended UTF-8
         * characters; they would encode to URIs which won't decode
         * back because of strict UTF-8 checks in URI decoding.
         * (However, we could just as well allow them here.)
         */
        goto uri_error;
    } else {
        /* Non-BMP characters within valid UTF-8 range: encode as is.
         * They'll decode back into surrogate pairs if the escaped
         * output is decoded.
         */
        ;
    }
 
    len = duk_unicode_encode_xutf8((duk_ucodepoint_t) cp, xutf8_buf);
    for (i = 0; i < len; i++) {
        t = (int) xutf8_buf[i];
        DUK_BW_WRITE_RAW_U8_3(tfm_ctx->thr,
                              &tfm_ctx->bw,
                              DUK_ASC_PERCENT,
                              (duk_uint8_t) duk_uc_nybbles[t >> 4],
                                      (duk_uint8_t) duk_uc_nybbles[t & 0x0f]);
    }
 
    return;
 
 uri_error:
    DUK_ERROR(tfm_ctx->thr, DUK_ERR_URI_ERROR, "invalid input");
}
 
DUK_LOCAL void duk__transform_callback_decode_uri(duk__transform_context *tfm_ctx, const void *udata, duk_codepoint_t cp) {
    const duk_uint8_t *reserved_table = (const duk_uint8_t *) udata;
    duk_small_uint_t utf8_blen;
    duk_codepoint_t min_cp;
    duk_small_int_t t;  /* must be signed */
    duk_small_uint_t i;
 
    /* Maximum write size: XUTF8 path writes max DUK_UNICODE_MAX_XUTF8_LENGTH,
     * percent escape path writes max two times CESU-8 encoded BMP length.
     */
    DUK_BW_ENSURE(tfm_ctx->thr,
                  &tfm_ctx->bw,
                  (DUK_UNICODE_MAX_XUTF8_LENGTH >= 2 * DUK_UNICODE_MAX_CESU8_BMP_LENGTH ?
                  DUK_UNICODE_MAX_XUTF8_LENGTH : DUK_UNICODE_MAX_CESU8_BMP_LENGTH));
 
    if (cp == (duk_codepoint_t) '%') {
        const duk_uint8_t *p = tfm_ctx->p;
        duk_size_t left = (duk_size_t) (tfm_ctx->p_end - p);  /* bytes left */
 
        DUK_DDD(DUK_DDDPRINT("percent encoding, left=%ld", (long) left));
 
        if (left < 2) {
            goto uri_error;
        }
 
        t = duk__decode_hex_escape(p, 2);
        DUK_DDD(DUK_DDDPRINT("first byte: %ld", (long) t));
        if (t < 0) {
            goto uri_error;
        }
 
        if (t < 0x80) {
            if (DUK__CHECK_BITMASK(reserved_table, t)) {
                /* decode '%xx' to '%xx' if decoded char in reserved set */
                DUK_ASSERT(tfm_ctx->p - 1 >= tfm_ctx->p_start);
                DUK_BW_WRITE_RAW_U8_3(tfm_ctx->thr,
                                      &tfm_ctx->bw,
                                      DUK_ASC_PERCENT,
                                      p[0],
                                      p[1]);
            } else {
                DUK_BW_WRITE_RAW_U8(tfm_ctx->thr, &tfm_ctx->bw, (duk_uint8_t) t);
            }
            tfm_ctx->p += 2;
            return;
        }
 
        /* Decode UTF-8 codepoint from a sequence of hex escapes.  The
         * first byte of the sequence has been decoded to 't'.
         *
         * Note that UTF-8 validation must be strict according to the
         * specification: E5.1 Section 15.1.3, decode algorithm step
         * 4.d.vii.8.  URIError from non-shortest encodings is also
         * specifically noted in the spec.
         */
 
        DUK_ASSERT(t >= 0x80);
        if (t < 0xc0) {
            /* continuation byte */
            goto uri_error;
        } else if (t < 0xe0) {
            /* 110x xxxx; 2 bytes */
            utf8_blen = 2;
            min_cp = 0x80L;
            cp = t & 0x1f;
        } else if (t < 0xf0) {
            /* 1110 xxxx; 3 bytes */
            utf8_blen = 3;
            min_cp = 0x800L;
            cp = t & 0x0f;
        } else if (t < 0xf8) {
            /* 1111 0xxx; 4 bytes */
            utf8_blen = 4;
            min_cp = 0x10000L;
            cp = t & 0x07;
        } else {
            /* extended utf-8 not allowed for URIs */
            goto uri_error;
        }
 
        if (left < utf8_blen * 3 - 1) {
            /* '%xx%xx...%xx', p points to char after first '%' */
            goto uri_error;
        }
 
        p += 3;
        for (i = 1; i < utf8_blen; i++) {
            /* p points to digit part ('%xy', p points to 'x') */
            t = duk__decode_hex_escape(p, 2);
            DUK_DDD(DUK_DDDPRINT("i=%ld utf8_blen=%ld cp=%ld t=0x%02lx",
                                 (long) i, (long) utf8_blen, (long) cp, (unsigned long) t));
            if (t < 0) {
                goto uri_error;
            }
            if ((t & 0xc0) != 0x80) {
                goto uri_error;
            }
            cp = (cp << 6) + (t & 0x3f);
            p += 3;
        }
        p--;  /* p overshoots */
        tfm_ctx->p = p;
 
        DUK_DDD(DUK_DDDPRINT("final cp=%ld, min_cp=%ld", (long) cp, (long) min_cp));
 
        if (cp < min_cp || cp > 0x10ffffL || (cp >= 0xd800L && cp <= 0xdfffL)) {
            goto uri_error;
        }
 
        /* The E5.1 algorithm checks whether or not a decoded codepoint
         * is below 0x80 and perhaps may be in the "reserved" set.
         * This seems pointless because the single byte UTF-8 case is
         * handled separately, and non-shortest encodings are rejected.
         * So, 'cp' cannot be below 0x80 here, and thus cannot be in
         * the reserved set.
         */
 
        /* utf-8 validation ensures these */
        DUK_ASSERT(cp >= 0x80L && cp <= 0x10ffffL);
 
        if (cp >= 0x10000L) {
            cp -= 0x10000L;
            DUK_ASSERT(cp < 0x100000L);
 
            DUK_BW_WRITE_RAW_XUTF8(tfm_ctx->thr, &tfm_ctx->bw, ((cp >> 10) + 0xd800L));
            DUK_BW_WRITE_RAW_XUTF8(tfm_ctx->thr, &tfm_ctx->bw, ((cp & 0x03ffUL) + 0xdc00L));
        } else {
            DUK_BW_WRITE_RAW_XUTF8(tfm_ctx->thr, &tfm_ctx->bw, cp);
        }
    } else {
        DUK_BW_WRITE_RAW_XUTF8(tfm_ctx->thr, &tfm_ctx->bw, cp);
    }
    return;
 
 uri_error:
    DUK_ERROR(tfm_ctx->thr, DUK_ERR_URI_ERROR, "invalid input");
}
 
#ifdef DUK_USE_SECTION_B
DUK_LOCAL void duk__transform_callback_escape(duk__transform_context *tfm_ctx, const void *udata, duk_codepoint_t cp) {
    DUK_UNREF(udata);
 
    DUK_BW_ENSURE(tfm_ctx->thr, &tfm_ctx->bw, 6);
 
    if (cp < 0) {
        goto esc_error;
    } else if ((cp < 0x80L) && DUK__CHECK_BITMASK(duk__escape_unescaped_table, cp)) {
        DUK_BW_WRITE_RAW_U8(tfm_ctx->thr, &tfm_ctx->bw, (duk_uint8_t) cp);
    } else if (cp < 0x100L) {
        DUK_BW_WRITE_RAW_U8_3(tfm_ctx->thr,
                              &tfm_ctx->bw,
                              (duk_uint8_t) DUK_ASC_PERCENT,
                              (duk_uint8_t) duk_uc_nybbles[cp >> 4],
                              (duk_uint8_t) duk_uc_nybbles[cp & 0x0f]);
    } else if (cp < 0x10000L) {
        DUK_BW_WRITE_RAW_U8_6(tfm_ctx->thr,
                              &tfm_ctx->bw,
                              (duk_uint8_t) DUK_ASC_PERCENT,
                              (duk_uint8_t) DUK_ASC_LC_U,
                              (duk_uint8_t) duk_uc_nybbles[cp >> 12],
                              (duk_uint8_t) duk_uc_nybbles[(cp >> 8) & 0x0f],
                              (duk_uint8_t) duk_uc_nybbles[(cp >> 4) & 0x0f],
                              (duk_uint8_t) duk_uc_nybbles[cp & 0x0f]);
    } else {
        /* Characters outside BMP cannot be escape()'d.  We could
         * encode them as surrogate pairs (for codepoints inside
         * valid UTF-8 range, but not extended UTF-8).  Because
         * escape() and unescape() are legacy functions, we don't.
         */
        goto esc_error;
    }
 
    return;
 
 esc_error:
    DUK_ERROR_TYPE(tfm_ctx->thr, "invalid input");
}
 
DUK_LOCAL void duk__transform_callback_unescape(duk__transform_context *tfm_ctx, const void *udata, duk_codepoint_t cp) {
    duk_small_int_t t;
 
    DUK_UNREF(udata);
 
    if (cp == (duk_codepoint_t) '%') {
        const duk_uint8_t *p = tfm_ctx->p;
        duk_size_t left = (duk_size_t) (tfm_ctx->p_end - p);  /* bytes left */
 
        if (left >= 5 && p[0] == 'u' &&
            ((t = duk__decode_hex_escape(p + 1, 4)) >= 0)) {
            cp = (duk_codepoint_t) t;
            tfm_ctx->p += 5;
        } else if (left >= 2 &&
                   ((t = duk__decode_hex_escape(p, 2)) >= 0)) {
            cp = (duk_codepoint_t) t;
            tfm_ctx->p += 2;
        }
    }
 
    DUK_BW_WRITE_ENSURE_XUTF8(tfm_ctx->thr, &tfm_ctx->bw, cp);
}
#endif  /* DUK_USE_SECTION_B */
 
/*
 *  Eval
 *
 *  Eval needs to handle both a "direct eval" and an "indirect eval".
 *  Direct eval handling needs access to the caller's activation so that its
 *  lexical environment can be accessed.  A direct eval is only possible from
 *  Ecmascript code; an indirect eval call is possible also from C code.
 *  When an indirect eval call is made from C code, there may not be a
 *  calling activation at all which needs careful handling.
 */
 
DUK_INTERNAL duk_ret_t duk_bi_global_object_eval(duk_context *ctx) {
    duk_hthread *thr = (duk_hthread *) ctx;
    duk_hstring *h;
    duk_activation *act_caller;
    duk_activation *act_eval;
    duk_activation *act;
    duk_hcompiledfunction *func;
    duk_hobject *outer_lex_env;
    duk_hobject *outer_var_env;
    duk_bool_t this_to_global = 1;
    duk_small_uint_t comp_flags;
    duk_int_t level = -2;
 
    DUK_ASSERT(duk_get_top(ctx) == 1 || duk_get_top(ctx) == 2);  /* 2 when called by debugger */
    DUK_ASSERT(thr->callstack_top >= 1);  /* at least this function exists */
    DUK_ASSERT(((thr->callstack + thr->callstack_top - 1)->flags & DUK_ACT_FLAG_DIRECT_EVAL) == 0 || /* indirect eval */
               (thr->callstack_top >= 2));  /* if direct eval, calling activation must exist */
 
    /*
     *  callstack_top - 1 --> this function
     *  callstack_top - 2 --> caller (may not exist)
     *
     *  If called directly from C, callstack_top might be 1.  If calling
     *  activation doesn't exist, call must be indirect.
     */
 
    h = duk_get_hstring(ctx, 0);
    if (!h) {
        return 1;  /* return arg as-is */
    }
 
#if defined(DUK_USE_DEBUGGER_SUPPORT)
    /* NOTE: level is used only by the debugger and should never be present
     * for an Ecmascript eval().
     */
    DUK_ASSERT(level == -2);  /* by default, use caller's environment */
    if (duk_get_top(ctx) >= 2 && duk_is_number(ctx, 1)) {
        level = duk_get_int(ctx, 1);
    }
    DUK_ASSERT(level <= -2);  /* This is guaranteed by debugger code. */
#endif
 
    /* [ source ] */
 
    comp_flags = DUK_JS_COMPILE_FLAG_EVAL;
    act_eval = thr->callstack + thr->callstack_top - 1;    /* this function */
    if (thr->callstack_top >= (duk_size_t) -level) {
        /* Have a calling activation, check for direct eval (otherwise
         * assume indirect eval.
         */
        act_caller = thr->callstack + thr->callstack_top + level;  /* caller */
        if ((act_caller->flags & DUK_ACT_FLAG_STRICT) &&
            (act_eval->flags & DUK_ACT_FLAG_DIRECT_EVAL)) {
            /* Only direct eval inherits strictness from calling code
             * (E5.1 Section 10.1.1).
             */
            comp_flags |= DUK_JS_COMPILE_FLAG_STRICT;
        }
    } else {
        DUK_ASSERT((act_eval->flags & DUK_ACT_FLAG_DIRECT_EVAL) == 0);
    }
    act_caller = NULL;  /* avoid dereference after potential callstack realloc */
    act_eval = NULL;
 
    duk_push_hstring_stridx(ctx, DUK_STRIDX_INPUT);  /* XXX: copy from caller? */
    duk_js_compile(thr,
                   (const duk_uint8_t *) DUK_HSTRING_GET_DATA(h),
                   (duk_size_t) DUK_HSTRING_GET_BYTELEN(h),
                   comp_flags);
    func = (duk_hcompiledfunction *) duk_get_hobject(ctx, -1);
    DUK_ASSERT(func != NULL);
    DUK_ASSERT(DUK_HOBJECT_IS_COMPILEDFUNCTION((duk_hobject *) func));
 
    /* [ source template ] */
 
    /* E5 Section 10.4.2 */
    DUK_ASSERT(thr->callstack_top >= 1);
    act = thr->callstack + thr->callstack_top - 1;  /* this function */
    if (act->flags & DUK_ACT_FLAG_DIRECT_EVAL) {
        DUK_ASSERT(thr->callstack_top >= 2);
        act = thr->callstack + thr->callstack_top + level;  /* caller */
        if (act->lex_env == NULL) {
            DUK_ASSERT(act->var_env == NULL);
            DUK_DDD(DUK_DDDPRINT("delayed environment initialization"));
 
            /* this may have side effects, so re-lookup act */
            duk_js_init_activation_environment_records_delayed(thr, act);
            act = thr->callstack + thr->callstack_top + level;
        }
        DUK_ASSERT(act->lex_env != NULL);
        DUK_ASSERT(act->var_env != NULL);
 
        this_to_global = 0;
 
        if (DUK_HOBJECT_HAS_STRICT((duk_hobject *) func)) {
            duk_hobject *new_env;
            duk_hobject *act_lex_env;
 
            DUK_DDD(DUK_DDDPRINT("direct eval call to a strict function -> "
                                 "var_env and lex_env to a fresh env, "
                                 "this_binding to caller's this_binding"));
 
            act = thr->callstack + thr->callstack_top + level;  /* caller */
            act_lex_env = act->lex_env;
            act = NULL;  /* invalidated */
 
            (void) duk_push_object_helper_proto(ctx,
                                                DUK_HOBJECT_FLAG_EXTENSIBLE |
                                                DUK_HOBJECT_CLASS_AS_FLAGS(DUK_HOBJECT_CLASS_DECENV),
                                                act_lex_env);
            new_env = duk_require_hobject(ctx, -1);
            DUK_ASSERT(new_env != NULL);
            DUK_DDD(DUK_DDDPRINT("new_env allocated: %!iO",
                                 (duk_heaphdr *) new_env));
 
            outer_lex_env = new_env;
            outer_var_env = new_env;
 
            duk_insert(ctx, 0);  /* stash to bottom of value stack to keep new_env reachable for duration of eval */
 
            /* compiler's responsibility */
            DUK_ASSERT(DUK_HOBJECT_HAS_NEWENV((duk_hobject *) func));
        } else {
            DUK_DDD(DUK_DDDPRINT("direct eval call to a non-strict function -> "
                                 "var_env and lex_env to caller's envs, "
                                 "this_binding to caller's this_binding"));
 
            outer_lex_env = act->lex_env;
            outer_var_env = act->var_env;
 
            /* compiler's responsibility */
            DUK_ASSERT(!DUK_HOBJECT_HAS_NEWENV((duk_hobject *) func));
        }
    } else {
        DUK_DDD(DUK_DDDPRINT("indirect eval call -> var_env and lex_env to "
                             "global object, this_binding to global object"));
 
        this_to_global = 1;
        outer_lex_env = thr->builtins[DUK_BIDX_GLOBAL_ENV];
        outer_var_env = thr->builtins[DUK_BIDX_GLOBAL_ENV];
    }
    act = NULL;
 
    /* Eval code doesn't need an automatic .prototype object. */
    duk_js_push_closure(thr, func, outer_var_env, outer_lex_env, 0 /*add_auto_proto*/);
 
    /* [ source template closure ] */
 
    if (this_to_global) {
        DUK_ASSERT(thr->builtins[DUK_BIDX_GLOBAL] != NULL);
        duk_push_hobject_bidx(ctx, DUK_BIDX_GLOBAL);
    } else {
        duk_tval *tv;
        DUK_ASSERT(thr->callstack_top >= 2);
        act = thr->callstack + thr->callstack_top + level;  /* caller */
        tv = thr->valstack + act->idx_bottom - 1;  /* this is just beneath bottom */
        DUK_ASSERT(tv >= thr->valstack);
        duk_push_tval(ctx, tv);
    }
 
    DUK_DDD(DUK_DDDPRINT("eval -> lex_env=%!iO, var_env=%!iO, this_binding=%!T",
                         (duk_heaphdr *) outer_lex_env,
                         (duk_heaphdr *) outer_var_env,
                         duk_get_tval(ctx, -1)));
 
    /* [ source template closure this ] */
 
    duk_call_method(ctx, 0);
 
    /* [ source template result ] */
 
    return 1;
}
 
/*
 *  Parsing of ints and floats
 */
 
DUK_INTERNAL duk_ret_t duk_bi_global_object_parse_int(duk_context *ctx) {
    duk_int32_t radix;
    duk_small_uint_t s2n_flags;
 
    DUK_ASSERT_TOP(ctx, 2);
    duk_to_string(ctx, 0);
 
    radix = duk_to_int32(ctx, 1);
 
    s2n_flags = DUK_S2N_FLAG_TRIM_WHITE |
                DUK_S2N_FLAG_ALLOW_GARBAGE |
                DUK_S2N_FLAG_ALLOW_PLUS |
                DUK_S2N_FLAG_ALLOW_MINUS |
                DUK_S2N_FLAG_ALLOW_LEADING_ZERO |
                DUK_S2N_FLAG_ALLOW_AUTO_HEX_INT;
 
    /* Specification stripPrefix maps to DUK_S2N_FLAG_ALLOW_AUTO_HEX_INT.
     *
     * Don't autodetect octals (from leading zeroes), require user code to
     * provide an explicit radix 8 for parsing octal.  See write-up from Mozilla:
     * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/parseInt#ECMAScript_5_Removes_Octal_Interpretation
     */
 
    if (radix != 0) {
        if (radix < 2 || radix > 36) {
            goto ret_nan;
        }
        if (radix != 16) {
            s2n_flags &= ~DUK_S2N_FLAG_ALLOW_AUTO_HEX_INT;
        }
    } else {
        radix = 10;
    }
 
    duk_dup(ctx, 0);
    duk_numconv_parse(ctx, radix, s2n_flags);
    return 1;
 
 ret_nan:
    duk_push_nan(ctx);
    return 1;
}
 
DUK_INTERNAL duk_ret_t duk_bi_global_object_parse_float(duk_context *ctx) {
    duk_small_uint_t s2n_flags;
    duk_int32_t radix;
 
    DUK_ASSERT_TOP(ctx, 1);
    duk_to_string(ctx, 0);
 
    radix = 10;
 
    /* XXX: check flags */
    s2n_flags = DUK_S2N_FLAG_TRIM_WHITE |
                DUK_S2N_FLAG_ALLOW_EXP |
                DUK_S2N_FLAG_ALLOW_GARBAGE |
                DUK_S2N_FLAG_ALLOW_PLUS |
                DUK_S2N_FLAG_ALLOW_MINUS |
                DUK_S2N_FLAG_ALLOW_INF |
                DUK_S2N_FLAG_ALLOW_FRAC |
                DUK_S2N_FLAG_ALLOW_NAKED_FRAC |
                DUK_S2N_FLAG_ALLOW_EMPTY_FRAC |
                DUK_S2N_FLAG_ALLOW_LEADING_ZERO;
 
    duk_numconv_parse(ctx, radix, s2n_flags);
    return 1;
}
 
/*
 *  Number checkers
 */
 
DUK_INTERNAL duk_ret_t duk_bi_global_object_is_nan(duk_context *ctx) {
    duk_double_t d = duk_to_number(ctx, 0);
    duk_push_boolean(ctx, DUK_ISNAN(d));
    return 1;
}
 
DUK_INTERNAL duk_ret_t duk_bi_global_object_is_finite(duk_context *ctx) {
    duk_double_t d = duk_to_number(ctx, 0);
    duk_push_boolean(ctx, DUK_ISFINITE(d));
    return 1;
}
 
/*
 *  URI handling
 */
 
DUK_INTERNAL duk_ret_t duk_bi_global_object_decode_uri(duk_context *ctx) {
    return duk__transform_helper(ctx, duk__transform_callback_decode_uri, (const void *) duk__decode_uri_reserved_table);
}
 
DUK_INTERNAL duk_ret_t duk_bi_global_object_decode_uri_component(duk_context *ctx) {
    return duk__transform_helper(ctx, duk__transform_callback_decode_uri, (const void *) duk__decode_uri_component_reserved_table);
}
 
DUK_INTERNAL duk_ret_t duk_bi_global_object_encode_uri(duk_context *ctx) {
    return duk__transform_helper(ctx, duk__transform_callback_encode_uri, (const void *) duk__encode_uriunescaped_table);
}
 
DUK_INTERNAL duk_ret_t duk_bi_global_object_encode_uri_component(duk_context *ctx) {
    return duk__transform_helper(ctx, duk__transform_callback_encode_uri, (const void *) duk__encode_uricomponent_unescaped_table);
}
 
#ifdef DUK_USE_SECTION_B
DUK_INTERNAL duk_ret_t duk_bi_global_object_escape(duk_context *ctx) {
    return duk__transform_helper(ctx, duk__transform_callback_escape, (const void *) NULL);
}
 
DUK_INTERNAL duk_ret_t duk_bi_global_object_unescape(duk_context *ctx) {
    return duk__transform_helper(ctx, duk__transform_callback_unescape, (const void *) NULL);
}
#else  /* DUK_USE_SECTION_B */
DUK_INTERNAL duk_ret_t duk_bi_global_object_escape(duk_context *ctx) {
    DUK_UNREF(ctx);
    return DUK_RET_UNSUPPORTED_ERROR;
}
 
DUK_INTERNAL duk_ret_t duk_bi_global_object_unescape(duk_context *ctx) {
    DUK_UNREF(ctx);
    return DUK_RET_UNSUPPORTED_ERROR;
}
#endif  /* DUK_USE_SECTION_B */
 
#if defined(DUK_USE_BROWSER_LIKE) && (defined(DUK_USE_FILE_IO) || defined(DUK_USE_DEBUGGER_SUPPORT))
DUK_INTERNAL duk_ret_t duk_bi_global_object_print_helper(duk_context *ctx) {
    duk_hthread *thr = (duk_hthread *) ctx;
    duk_int_t magic;
    duk_idx_t nargs;
    const duk_uint8_t *buf;
    duk_size_t sz_buf;
    const char nl = (const char) DUK_ASC_LF;
#ifndef DUK_USE_PREFER_SIZE
    duk_uint8_t buf_stack[256];
#endif
#ifdef DUK_USE_FILE_IO
    duk_file *f_out;
#endif
 
    DUK_UNREF(thr);
 
    magic = duk_get_current_magic(ctx);
    DUK_UNREF(magic);
 
    nargs = duk_get_top(ctx);
 
    /* If argument count is 1 and first argument is a buffer, write the buffer
     * as raw data into the file without a newline; this allows exact control
     * over stdout/stderr without an additional entrypoint (useful for now).
     *
     * Otherwise current print/alert semantics are to ToString() coerce
     * arguments, join them with a single space, and append a newline.
     */
 
    if (nargs == 1 && duk_is_buffer(ctx, 0)) {
        buf = (const duk_uint8_t *) duk_get_buffer(ctx, 0, &sz_buf);
        DUK_ASSERT(buf != NULL);
    } else if (nargs > 0) {
#ifdef DUK_USE_PREFER_SIZE
        /* Compact but lots of churn. */
        duk_push_hstring_stridx(thr, DUK_STRIDX_SPACE);
        duk_insert(ctx, 0);
        duk_join(ctx, nargs);
        duk_push_string(thr, "\n");
        duk_concat(ctx, 2);
        buf = (const duk_uint8_t *) duk_get_lstring(ctx, -1, &sz_buf);
        DUK_ASSERT(buf != NULL);
#else  /* DUK_USE_PREFER_SIZE */
        /* Higher footprint, less churn. */
        duk_idx_t i;
        duk_size_t sz_str;
        const duk_uint8_t *p_str;
        duk_uint8_t *p;
 
        sz_buf = (duk_size_t) nargs;  /* spaces (nargs - 1) + newline */
        for (i = 0; i < nargs; i++) {
            (void) duk_to_lstring(ctx, i, &sz_str);
            sz_buf += sz_str;
        }
 
        if (sz_buf <= sizeof(buf_stack)) {
            p = (duk_uint8_t *) buf_stack;
        } else {
            p = (duk_uint8_t *) duk_push_fixed_buffer(ctx, sz_buf);
            DUK_ASSERT(p != NULL);
        }
 
        buf = (const duk_uint8_t *) p;
        for (i = 0; i < nargs; i++) {
            p_str = (const duk_uint8_t *) duk_get_lstring(ctx, i, &sz_str);
            DUK_ASSERT(p_str != NULL);
            DUK_MEMCPY((void *) p, (const void *) p_str, sz_str);
            p += sz_str;
            *p++ = (duk_uint8_t) (i == nargs - 1 ? DUK_ASC_LF : DUK_ASC_SPACE);
        }
        DUK_ASSERT((const duk_uint8_t *) p == buf + sz_buf);
#endif  /* DUK_USE_PREFER_SIZE */
    } else {
        buf = (const duk_uint8_t *) &nl;
        sz_buf = 1;
    }
 
    /* 'buf' contains the string to write, 'sz_buf' contains the length
     * (which may be zero).
     */
    DUK_ASSERT(buf != NULL);
 
    if (sz_buf == 0) {
        return 0;
    }
 
#ifdef DUK_USE_FILE_IO
    f_out = (magic ? DUK_STDERR : DUK_STDOUT);
    DUK_FWRITE((const void *) buf, 1, (size_t) sz_buf, f_out);
    DUK_FFLUSH(f_out);
#endif
 
#if defined(DUK_USE_DEBUGGER_SUPPORT) && defined(DUK_USE_DEBUGGER_FWD_PRINTALERT)
    if (DUK_HEAP_IS_DEBUGGER_ATTACHED(thr->heap)) {
        duk_debug_write_notify(thr, magic ? DUK_DBG_CMD_ALERT : DUK_DBG_CMD_PRINT);
        duk_debug_write_string(thr, (const char *) buf, sz_buf);
        duk_debug_write_eom(thr);
    }
#endif
    return 0;
}
#elif defined(DUK_USE_BROWSER_LIKE)  /* print provider */
DUK_INTERNAL duk_ret_t duk_bi_global_object_print_helper(duk_context *ctx) {
    DUK_UNREF(ctx);
    return 0;
}
#else  /* print provider */
DUK_INTERNAL duk_ret_t duk_bi_global_object_print_helper(duk_context *ctx) {
    DUK_UNREF(ctx);
    return DUK_RET_UNSUPPORTED_ERROR;
}
#endif  /* print provider */
 
/*
 *  CommonJS require() and modules support
 */
 
#if defined(DUK_USE_COMMONJS_MODULES)
DUK_LOCAL void duk__bi_global_resolve_module_id(duk_context *ctx, const char *req_id, const char *mod_id) {
    duk_hthread *thr = (duk_hthread *) ctx;
    duk_uint8_t buf[DUK_BI_COMMONJS_MODULE_ID_LIMIT];
    duk_uint8_t *p;
    duk_uint8_t *q;
    duk_uint8_t *q_last;  /* last component */
    duk_int_t int_rc;
 
    DUK_ASSERT(req_id != NULL);
    /* mod_id may be NULL */
 
    /*
     *  A few notes on the algorithm:
     *
     *    - Terms are not allowed to begin with a period unless the term
     *      is either '.' or '..'.  This simplifies implementation (and
     *      is within CommonJS modules specification).
     *
     *    - There are few output bound checks here.  This is on purpose:
     *      the resolution input is length checked and the output is never
     *      longer than the input.  The resolved output is written directly
     *      over the input because it's never longer than the input at any
     *      point in the algorithm.
     *
     *    - Non-ASCII characters are processed as individual bytes and
     *      need no special treatment.  However, U+0000 terminates the
     *      algorithm; this is not an issue because U+0000 is not a
     *      desirable term character anyway.
     */
 
    /*
     *  Set up the resolution input which is the requested ID directly
     *  (if absolute or no current module path) or with current module
     *  ID prepended (if relative and current module path exists).
     *
     *  Suppose current module is 'foo/bar' and relative path is './quux'.
     *  The 'bar' component must be replaced so the initial input here is
     *  'foo/bar/.././quux'.
     */
 
    if (mod_id != NULL && req_id[0] == '.') {
        int_rc = DUK_SNPRINTF((char *) buf, sizeof(buf), "%s/../%s", mod_id, req_id);
    } else {
        int_rc = DUK_SNPRINTF((char *) buf, sizeof(buf), "%s", req_id);
    }
    if (int_rc >= (duk_int_t) sizeof(buf) || int_rc < 0) {
        /* Potentially truncated, NUL not guaranteed in any case.
         * The (int_rc < 0) case should not occur in practice.
         */
        DUK_DD(DUK_DDPRINT("resolve error: temporary working module ID doesn't fit into resolve buffer"));
        goto resolve_error;
    }
    DUK_ASSERT(DUK_STRLEN((const char *) buf) < sizeof(buf));  /* at most sizeof(buf) - 1 */
 
    DUK_DDD(DUK_DDDPRINT("input module id: '%s'", (const char *) buf));
 
    /*
     *  Resolution loop.  At the top of the loop we're expecting a valid
     *  term: '.', '..', or a non-empty identifier not starting with a period.
     */
 
    p = buf;
    q = buf;
    for (;;) {
        duk_uint_fast8_t c;
 
        /* Here 'p' always points to the start of a term.
         *
         * We can also unconditionally reset q_last here: if this is
         * the last (non-empty) term q_last will have the right value
         * on loop exit.
         */
 
        DUK_ASSERT(p >= q);  /* output is never longer than input during resolution */
 
        DUK_DDD(DUK_DDDPRINT("resolve loop top: p -> '%s', q=%p, buf=%p",
                             (const char *) p, (void *) q, (void *) buf));
 
        q_last = q;
 
        c = *p++;
        if (DUK_UNLIKELY(c == 0)) {
            DUK_DD(DUK_DDPRINT("resolve error: requested ID must end with a non-empty term"));
            goto resolve_error;
        } else if (DUK_UNLIKELY(c == '.')) {
            c = *p++;
            if (c == '/') {
                /* Term was '.' and is eaten entirely (including dup slashes). */
                goto eat_dup_slashes;
            }
            if (c == '.' && *p == '/') {
                /* Term was '..', backtrack resolved name by one component.
                 *  q[-1] = previous slash (or beyond start of buffer)
                 *  q[-2] = last char of previous component (or beyond start of buffer)
                 */
                p++;  /* eat (first) input slash */
                DUK_ASSERT(q >= buf);
                if (q == buf) {
                    DUK_DD(DUK_DDPRINT("resolve error: term was '..' but nothing to backtrack"));
                    goto resolve_error;
                }
                DUK_ASSERT(*(q - 1) == '/');
                q--;  /* backtrack to last output slash (dups already eliminated) */
                for (;;) {
                    /* Backtrack to previous slash or start of buffer. */
                    DUK_ASSERT(q >= buf);
                    if (q == buf) {
                        break;
                    }
                    if (*(q - 1) == '/') {
                        break;
                    }
                    q--;
                }
                goto eat_dup_slashes;
            }
            DUK_DD(DUK_DDPRINT("resolve error: term begins with '.' but is not '.' or '..' (not allowed now)"));
            goto resolve_error;
        } else if (DUK_UNLIKELY(c == '/')) {
            /* e.g. require('/foo'), empty terms not allowed */
            DUK_DD(DUK_DDPRINT("resolve error: empty term (not allowed now)"));
            goto resolve_error;
        } else {
            for (;;) {
                /* Copy term name until end or '/'. */
                *q++ = c;
                c = *p++;
                if (DUK_UNLIKELY(c == 0)) {
                    /* This was the last term, and q_last was
                     * updated to match this term at loop top.
                     */
                    goto loop_done;
                } else if (DUK_UNLIKELY(c == '/')) {
                    *q++ = '/';
                    break;
                } else {
                    /* write on next loop */
                }
            }
        }
 
     eat_dup_slashes:
        for (;;) {
            /* eat dup slashes */
            c = *p;
            if (DUK_LIKELY(c != '/')) {
                break;
            }
            p++;
        }
    }
 loop_done:
    /* Output #1: resolved absolute name */
    DUK_ASSERT(q >= buf);
    duk_push_lstring(ctx, (const char *) buf, (size_t) (q - buf));
 
    /* Output #2: last component name */
    DUK_ASSERT(q >= q_last);
    DUK_ASSERT(q_last >= buf);
    duk_push_lstring(ctx, (const char *) q_last, (size_t) (q - q_last));
 
    DUK_DD(DUK_DDPRINT("after resolving module name: buf=%p, q_last=%p, q=%p",
                       (void *) buf, (void *) q_last, (void *) q));
    return;
 
 resolve_error:
    DUK_ERROR_FMT1(thr, DUK_ERR_TYPE_ERROR, "cannot resolve module id: %s", (const char *) req_id);
}
#endif  /* DUK_USE_COMMONJS_MODULES */
 
#if defined(DUK_USE_COMMONJS_MODULES)
/* Stack indices for better readability */
#define DUK__IDX_REQUESTED_ID   0  /* Module id requested */
#define DUK__IDX_REQUIRE        1  /* Current require() function */
#define DUK__IDX_REQUIRE_ID     2  /* The base ID of the current require() function, resolution base */
#define DUK__IDX_RESOLVED_ID    3  /* Resolved, normalized absolute module ID */
#define DUK__IDX_LASTCOMP       4  /* Last component name in resolved path */
#define DUK__IDX_DUKTAPE        5  /* Duktape object */
#define DUK__IDX_MODLOADED      6  /* Duktape.modLoaded[] module cache */
#define DUK__IDX_UNDEFINED      7  /* 'undefined', artifact of lookup */
#define DUK__IDX_FRESH_REQUIRE  8  /* New require() function for module, updated resolution base */
#define DUK__IDX_EXPORTS        9  /* Default exports table */
#define DUK__IDX_MODULE         10  /* Module object containing module.exports, etc */
 
DUK_INTERNAL duk_ret_t duk_bi_global_object_require(duk_context *ctx) {
    const char *str_req_id;  /* requested identifier */
    const char *str_mod_id;  /* require.id of current module */
    duk_int_t pcall_rc;
 
    /* NOTE: we try to minimize code size by avoiding unnecessary pops,
     * so the stack looks a bit cluttered in this function.  DUK_ASSERT_TOP()
     * assertions are used to ensure stack configuration is correct at each
     * step.
     */
 
    /*
     *  Resolve module identifier into canonical absolute form.
     */
 
    str_req_id = duk_require_string(ctx, DUK__IDX_REQUESTED_ID);
    duk_push_current_function(ctx);
    duk_get_prop_stridx(ctx, -1, DUK_STRIDX_ID);
    str_mod_id = duk_get_string(ctx, DUK__IDX_REQUIRE_ID);  /* ignore non-strings */
    DUK_DDD(DUK_DDDPRINT("resolve module id: requested=%!T, currentmodule=%!T",
                         duk_get_tval(ctx, DUK__IDX_REQUESTED_ID),
                         duk_get_tval(ctx, DUK__IDX_REQUIRE_ID)));
    duk__bi_global_resolve_module_id(ctx, str_req_id, str_mod_id);
    str_req_id = NULL;
    str_mod_id = NULL;
    DUK_DDD(DUK_DDDPRINT("resolved module id: requested=%!T, currentmodule=%!T, result=%!T, lastcomp=%!T",
                         duk_get_tval(ctx, DUK__IDX_REQUESTED_ID),
                         duk_get_tval(ctx, DUK__IDX_REQUIRE_ID),
                         duk_get_tval(ctx, DUK__IDX_RESOLVED_ID),
                         duk_get_tval(ctx, DUK__IDX_LASTCOMP)));
 
    /* [ requested_id require require.id resolved_id last_comp ] */
    DUK_ASSERT_TOP(ctx, DUK__IDX_LASTCOMP + 1);
 
    /*
     *  Cached module check.
     *
     *  If module has been loaded or its loading has already begun without
     *  finishing, return the same cached value ('exports').  The value is
     *  registered when module load starts so that circular references can
     *  be supported to some extent.
     */
 
    duk_push_hobject_bidx(ctx, DUK_BIDX_DUKTAPE);
    duk_get_prop_stridx(ctx, DUK__IDX_DUKTAPE, DUK_STRIDX_MOD_LOADED);  /* Duktape.modLoaded */
    (void) duk_require_hobject(ctx, DUK__IDX_MODLOADED);
    DUK_ASSERT_TOP(ctx, DUK__IDX_MODLOADED + 1);
 
    duk_dup(ctx, DUK__IDX_RESOLVED_ID);
    if (duk_get_prop(ctx, DUK__IDX_MODLOADED)) {
        /* [ requested_id require require.id resolved_id last_comp Duktape Duktape.modLoaded Duktape.modLoaded[id] ] */
        DUK_DD(DUK_DDPRINT("module already loaded: %!T",
                           duk_get_tval(ctx, DUK__IDX_RESOLVED_ID)));
        duk_get_prop_stridx(ctx, -1, DUK_STRIDX_EXPORTS);  /* return module.exports */
        return 1;
    }
    DUK_ASSERT_TOP(ctx, DUK__IDX_UNDEFINED + 1);
 
    /* [ requested_id require require.id resolved_id last_comp Duktape Duktape.modLoaded undefined ] */
 
    /*
     *  Module not loaded (and loading not started previously).
     *
     *  Create a new require() function with 'id' set to resolved ID
     *  of module being loaded.  Also create 'exports' and 'module'
     *  tables but don't register exports to the loaded table yet.
     *  We don't want to do that unless the user module search callbacks
     *  succeeds in finding the module.
     */
 
    DUK_D(DUK_DPRINT("loading module %!T, resolution base %!T, requested ID %!T -> resolved ID %!T, last component %!T",
                         duk_get_tval(ctx, DUK__IDX_RESOLVED_ID),
                         duk_get_tval(ctx, DUK__IDX_REQUIRE_ID),
                         duk_get_tval(ctx, DUK__IDX_REQUESTED_ID),
                         duk_get_tval(ctx, DUK__IDX_RESOLVED_ID),
                         duk_get_tval(ctx, DUK__IDX_LASTCOMP)));
 
    /* Fresh require: require.id is left configurable (but not writable)
     * so that is not easy to accidentally tweak it, but it can still be
     * done with Object.defineProperty().
     *
     * XXX: require.id could also be just made non-configurable, as there
     * is no practical reason to touch it.
     */
    duk_push_c_function(ctx, duk_bi_global_object_require, 1 /*nargs*/);
    duk_push_hstring_stridx(ctx, DUK_STRIDX_REQUIRE);
    duk_xdef_prop_stridx(ctx, DUK__IDX_FRESH_REQUIRE, DUK_STRIDX_NAME, DUK_PROPDESC_FLAGS_NONE);
    duk_dup(ctx, DUK__IDX_RESOLVED_ID);
    duk_xdef_prop_stridx(ctx, DUK__IDX_FRESH_REQUIRE, DUK_STRIDX_ID, DUK_PROPDESC_FLAGS_C);  /* a fresh require() with require.id = resolved target module id */
 
    /* Module table:
     * - module.exports: initial exports table (may be replaced by user)
     * - module.id is non-writable and non-configurable, as the CommonJS
     *   spec suggests this if possible
     * - module.filename: not set, defaults to resolved ID if not explicitly
     *   set by modSearch() (note capitalization, not .fileName, matches Node.js)
     * - module.name: not set, defaults to last component of resolved ID if
     *   not explicitly set by modSearch()
     */
    duk_push_object(ctx);  /* exports */
    duk_push_object(ctx);  /* module */
    duk_dup(ctx, DUK__IDX_EXPORTS);
    duk_xdef_prop_stridx(ctx, DUK__IDX_MODULE, DUK_STRIDX_EXPORTS, DUK_PROPDESC_FLAGS_WC);  /* module.exports = exports */
    duk_dup(ctx, DUK__IDX_RESOLVED_ID);  /* resolved id: require(id) must return this same module */
    duk_xdef_prop_stridx(ctx, DUK__IDX_MODULE, DUK_STRIDX_ID, DUK_PROPDESC_FLAGS_NONE);  /* module.id = resolved_id */
    duk_compact(ctx, DUK__IDX_MODULE);  /* module table remains registered to modLoaded, minimize its size */
    DUK_ASSERT_TOP(ctx, DUK__IDX_MODULE + 1);
 
    DUK_DD(DUK_DDPRINT("module table created: %!T", duk_get_tval(ctx, DUK__IDX_MODULE)));
 
    /* [ requested_id require require.id resolved_id last_comp Duktape Duktape.modLoaded undefined fresh_require exports module ] */
 
    /* Register the module table early to modLoaded[] so that we can
     * support circular references even in modSearch().  If an error
     * is thrown, we'll delete the reference.
     */
    duk_dup(ctx, DUK__IDX_RESOLVED_ID);
    duk_dup(ctx, DUK__IDX_MODULE);
    duk_put_prop(ctx, DUK__IDX_MODLOADED);  /* Duktape.modLoaded[resolved_id] = module */
 
    /*
     *  Call user provided module search function and build the wrapped
     *  module source code (if necessary).  The module search function
     *  can be used to implement pure Ecmacsript, pure C, and mixed
     *  Ecmascript/C modules.
     *
     *  The module search function can operate on the exports table directly
     *  (e.g. DLL code can register values to it).  It can also return a
     *  string which is interpreted as module source code (if a non-string
     *  is returned the module is assumed to be a pure C one).  If a module
     *  cannot be found, an error must be thrown by the user callback.
     *
     *  Because Duktape.modLoaded[] already contains the module being
     *  loaded, circular references for C modules should also work
     *  (although expected to be quite rare).
     */
 
    duk_push_string(ctx, "(function(require,exports,module){");
 
    /* Duktape.modSearch(resolved_id, fresh_require, exports, module). */
    duk_get_prop_stridx(ctx, DUK__IDX_DUKTAPE, DUK_STRIDX_MOD_SEARCH);  /* Duktape.modSearch */
    duk_dup(ctx, DUK__IDX_RESOLVED_ID);
    duk_dup(ctx, DUK__IDX_FRESH_REQUIRE);
    duk_dup(ctx, DUK__IDX_EXPORTS);
    duk_dup(ctx, DUK__IDX_MODULE);  /* [ ... Duktape.modSearch resolved_id last_comp fresh_require exports module ] */
    pcall_rc = duk_pcall(ctx, 4 /*nargs*/);  /* -> [ ... source ] */
    DUK_ASSERT_TOP(ctx, DUK__IDX_MODULE + 3);
 
    if (pcall_rc != DUK_EXEC_SUCCESS) {
        /* Delete entry in Duktape.modLoaded[] and rethrow. */
        goto delete_rethrow;
    }
 
    /* If user callback did not return source code, module loading
     * is finished (user callback initialized exports table directly).
     */
    if (!duk_is_string(ctx, -1)) {
        /* User callback did not return source code, so module loading
         * is finished: just update modLoaded with final module.exports
         * and we're done.
         */
        goto return_exports;
    }
 
    /* Finish the wrapped module source.  Force module.filename as the
     * function .fileName so it gets set for functions defined within a
     * module.  This also ensures loggers created within the module get
     * the module ID (or overridden filename) as their default logger name.
     * (Note capitalization: .filename matches Node.js while .fileName is
     * used elsewhere in Duktape.)
     */
    duk_push_string(ctx, "})");
    duk_concat(ctx, 3);
    if (!duk_get_prop_stridx(ctx, DUK__IDX_MODULE, DUK_STRIDX_FILENAME)) {
        /* module.filename for .fileName, default to resolved ID if
         * not present.
         */
        duk_pop(ctx);
        duk_dup(ctx, DUK__IDX_RESOLVED_ID);
    }
    duk_eval_raw(ctx, NULL, 0, DUK_COMPILE_EVAL);
 
    /* Module has now evaluated to a wrapped module function.  Force its
     * .name to match module.name (defaults to last component of resolved
     * ID) so that it is shown in stack traces too.  Note that we must not
     * introduce an actual name binding into the function scope (which is
     * usually the case with a named function) because it would affect the
     * scope seen by the module and shadow accesses to globals of the same name.
     * This is now done by compiling the function as anonymous and then forcing
     * its .name without setting a "has name binding" flag.
     */
 
    duk_push_hstring_stridx(ctx, DUK_STRIDX_NAME);
    if (!duk_get_prop_stridx(ctx, DUK__IDX_MODULE, DUK_STRIDX_NAME)) {
        /* module.name for .name, default to last component if
         * not present.
         */
        duk_pop(ctx);
        duk_dup(ctx, DUK__IDX_LASTCOMP);
    }
    duk_def_prop(ctx, -3, DUK_DEFPROP_HAVE_VALUE | DUK_DEFPROP_FORCE);
 
    /*
     *  Call the wrapped module function.
     *
     *  Use a protected call so that we can update Duktape.modLoaded[resolved_id]
     *  even if the module throws an error.
     */
 
    /* [ requested_id require require.id resolved_id last_comp Duktape Duktape.modLoaded undefined fresh_require exports module mod_func ] */
    DUK_ASSERT_TOP(ctx, DUK__IDX_MODULE + 2);
 
    duk_dup(ctx, DUK__IDX_EXPORTS);  /* exports (this binding) */
    duk_dup(ctx, DUK__IDX_FRESH_REQUIRE);  /* fresh require (argument) */
    duk_get_prop_stridx(ctx, DUK__IDX_MODULE, DUK_STRIDX_EXPORTS);  /* relookup exports from module.exports in case it was changed by modSearch */
    duk_dup(ctx, DUK__IDX_MODULE);  /* module (argument) */
    DUK_ASSERT_TOP(ctx, DUK__IDX_MODULE + 6);
 
    /* [ requested_id require require.id resolved_id last_comp Duktape Duktape.modLoaded undefined fresh_require exports module mod_func exports fresh_require exports module ] */
 
    pcall_rc = duk_pcall_method(ctx, 3 /*nargs*/);
    if (pcall_rc != DUK_EXEC_SUCCESS) {
        /* Module loading failed.  Node.js will forget the module
         * registration so that another require() will try to load
         * the module again.  Mimic that behavior.
         */
        goto delete_rethrow;
    }
 
    /* [ requested_id require require.id resolved_id last_comp Duktape Duktape.modLoaded undefined fresh_require exports module result(ignored) ] */
    DUK_ASSERT_TOP(ctx, DUK__IDX_MODULE + 2);
 
    /* fall through */
 
 return_exports:
    duk_get_prop_stridx(ctx, DUK__IDX_MODULE, DUK_STRIDX_EXPORTS);
    duk_compact(ctx, -1);  /* compact the exports table */
    return 1;  /* return module.exports */
 
 delete_rethrow:
    duk_dup(ctx, DUK__IDX_RESOLVED_ID);
    duk_del_prop(ctx, DUK__IDX_MODLOADED);  /* delete Duktape.modLoaded[resolved_id] */
    duk_throw(ctx);  /* rethrow original error */
    return 0;  /* not reachable */
}
 
#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
#else
DUK_INTERNAL duk_ret_t duk_bi_global_object_require(duk_context *ctx) {
    DUK_UNREF(ctx);
    return DUK_RET_UNSUPPORTED_ERROR;
}
#endif  /* DUK_USE_COMMONJS_MODULES */