duktape-1.5.2/src-separate/duk_api_string.c

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/*
 *  String manipulation
 */
 
#include "duk_internal.h"
 
DUK_LOCAL void duk__concat_and_join_helper(duk_context *ctx, duk_idx_t count_in, duk_bool_t is_join) {
    duk_hthread *thr = (duk_hthread *) ctx;
    duk_uint_t count;
    duk_uint_t i;
    duk_size_t idx;
    duk_size_t len;
    duk_hstring *h;
    duk_uint8_t *buf;
 
    DUK_ASSERT_CTX_VALID(ctx);
 
    if (DUK_UNLIKELY(count_in <= 0)) {
        if (count_in < 0) {
            DUK_ERROR_API(thr, DUK_STR_INVALID_COUNT);
            return;
        }
        DUK_ASSERT(count_in == 0);
        duk_push_hstring_stridx(ctx, DUK_STRIDX_EMPTY_STRING);
        return;
    }
    count = (duk_uint_t) count_in;
 
    if (is_join) {
        duk_size_t t1, t2, limit;
        h = duk_to_hstring(ctx, -((duk_idx_t) count) - 1);
        DUK_ASSERT(h != NULL);
 
        /* A bit tricky overflow test, see doc/code-issues.rst. */
        t1 = (duk_size_t) DUK_HSTRING_GET_BYTELEN(h);
        t2 = (duk_size_t) (count - 1);
        limit = (duk_size_t) DUK_HSTRING_MAX_BYTELEN;
        if (DUK_UNLIKELY(t2 != 0 && t1 > limit / t2)) {
            /* Combined size of separators already overflows */
            goto error_overflow;
        }
        len = (duk_size_t) (t1 * t2);
    } else {
        len = (duk_size_t) 0;
    }
 
    for (i = count; i >= 1; i--) {
        duk_size_t new_len;
        duk_to_string(ctx, -((duk_idx_t) i));
        h = duk_require_hstring(ctx, -((duk_idx_t) i));
        new_len = len + (duk_size_t) DUK_HSTRING_GET_BYTELEN(h);
 
        /* Impose a string maximum length, need to handle overflow
         * correctly.
         */
        if (new_len < len ||  /* wrapped */
            new_len > (duk_size_t) DUK_HSTRING_MAX_BYTELEN) {
            goto error_overflow;
        }
        len = new_len;
    }
 
    DUK_DDD(DUK_DDDPRINT("join/concat %lu strings, total length %lu bytes",
                         (unsigned long) count, (unsigned long) len));
 
    /* use stack allocated buffer to ensure reachability in errors (e.g. intern error) */
    buf = (duk_uint8_t *) duk_push_fixed_buffer(ctx, len);
    DUK_ASSERT(buf != NULL);
 
    /* [... (sep) str1 str2 ... strN buf] */
 
    idx = 0;
    for (i = count; i >= 1; i--) {
        if (is_join && i != count) {
            h = duk_require_hstring(ctx, -((duk_idx_t) count) - 2);  /* extra -1 for buffer */
            DUK_MEMCPY(buf + idx, DUK_HSTRING_GET_DATA(h), DUK_HSTRING_GET_BYTELEN(h));
            idx += DUK_HSTRING_GET_BYTELEN(h);
        }
        h = duk_require_hstring(ctx, -((duk_idx_t) i) - 1);  /* extra -1 for buffer */
        DUK_MEMCPY(buf + idx, DUK_HSTRING_GET_DATA(h), DUK_HSTRING_GET_BYTELEN(h));
        idx += DUK_HSTRING_GET_BYTELEN(h);
    }
 
    DUK_ASSERT(idx == len);
 
    /* [... (sep) str1 str2 ... strN buf] */
 
    /* get rid of the strings early to minimize memory use before intern */
 
    if (is_join) {
        duk_replace(ctx, -((duk_idx_t) count) - 2);  /* overwrite sep */
        duk_pop_n(ctx, count);
    } else {
        duk_replace(ctx, -((duk_idx_t) count) - 1);  /* overwrite str1 */
        duk_pop_n(ctx, count-1);
    }
 
    /* [... buf] */
 
    (void) duk_to_string(ctx, -1);
 
    /* [... res] */
    return;
 
 error_overflow:
    DUK_ERROR_RANGE(thr, DUK_STR_CONCAT_RESULT_TOO_LONG);
}
 
DUK_EXTERNAL void duk_concat(duk_context *ctx, duk_idx_t count) {
    DUK_ASSERT_CTX_VALID(ctx);
 
    duk__concat_and_join_helper(ctx, count, 0 /*is_join*/);
}
 
DUK_EXTERNAL void duk_join(duk_context *ctx, duk_idx_t count) {
    DUK_ASSERT_CTX_VALID(ctx);
 
    duk__concat_and_join_helper(ctx, count, 1 /*is_join*/);
}
 
/* XXX: could map/decode be unified with duk_unicode_support.c code?
 * Case conversion needs also the character surroundings though.
 */
 
DUK_EXTERNAL void duk_decode_string(duk_context *ctx, duk_idx_t index, duk_decode_char_function callback, void *udata) {
    duk_hthread *thr = (duk_hthread *) ctx;
    duk_hstring *h_input;
    const duk_uint8_t *p, *p_start, *p_end;
    duk_codepoint_t cp;
 
    DUK_ASSERT_CTX_VALID(ctx);
 
    h_input = duk_require_hstring(ctx, index);
    DUK_ASSERT(h_input != NULL);
 
    p_start = (const duk_uint8_t *) DUK_HSTRING_GET_DATA(h_input);
    p_end = p_start + DUK_HSTRING_GET_BYTELEN(h_input);
    p = p_start;
 
    for (;;) {
        if (p >= p_end) {
            break;
        }
        cp = (int) duk_unicode_decode_xutf8_checked(thr, &p, p_start, p_end);
        callback(udata, cp);
    }
}
 
DUK_EXTERNAL void duk_map_string(duk_context *ctx, duk_idx_t index, duk_map_char_function callback, void *udata) {
    duk_hthread *thr = (duk_hthread *) ctx;
    duk_hstring *h_input;
    duk_bufwriter_ctx bw_alloc;
    duk_bufwriter_ctx *bw;
    const duk_uint8_t *p, *p_start, *p_end;
    duk_codepoint_t cp;
 
    DUK_ASSERT_CTX_VALID(ctx);
 
    index = duk_normalize_index(ctx, index);
 
    h_input = duk_require_hstring(ctx, index);
    DUK_ASSERT(h_input != NULL);
 
    bw = &bw_alloc;
    DUK_BW_INIT_PUSHBUF(thr, bw, DUK_HSTRING_GET_BYTELEN(h_input));  /* reasonable output estimate */
 
    p_start = (const duk_uint8_t *) DUK_HSTRING_GET_DATA(h_input);
    p_end = p_start + DUK_HSTRING_GET_BYTELEN(h_input);
    p = p_start;
 
    for (;;) {
        /* XXX: could write output in chunks with fewer ensure calls,
         * but relative benefit would be small here.
         */
 
        if (p >= p_end) {
            break;
        }
        cp = (int) duk_unicode_decode_xutf8_checked(thr, &p, p_start, p_end);
        cp = callback(udata, cp);
 
        DUK_BW_WRITE_ENSURE_XUTF8(thr, bw, cp);
    }
 
    DUK_BW_COMPACT(thr, bw);
    duk_to_string(ctx, -1);
    duk_replace(ctx, index);
}
 
DUK_EXTERNAL void duk_substring(duk_context *ctx, duk_idx_t index, duk_size_t start_offset, duk_size_t end_offset) {
    duk_hthread *thr = (duk_hthread *) ctx;
    duk_hstring *h;
    duk_hstring *res;
    duk_size_t start_byte_offset;
    duk_size_t end_byte_offset;
 
    DUK_ASSERT_CTX_VALID(ctx);
 
    index = duk_require_normalize_index(ctx, index);
    h = duk_require_hstring(ctx, index);
    DUK_ASSERT(h != NULL);
 
    if (end_offset >= DUK_HSTRING_GET_CHARLEN(h)) {
        end_offset = DUK_HSTRING_GET_CHARLEN(h);
    }
    if (start_offset > end_offset) {
        start_offset = end_offset;
    }
 
    DUK_ASSERT_DISABLE(start_offset >= 0);
    DUK_ASSERT(start_offset <= end_offset && start_offset <= DUK_HSTRING_GET_CHARLEN(h));
    DUK_ASSERT_DISABLE(end_offset >= 0);
    DUK_ASSERT(end_offset >= start_offset && end_offset <= DUK_HSTRING_GET_CHARLEN(h));
 
    /* guaranteed by string limits */
    DUK_ASSERT(start_offset <= DUK_UINT32_MAX);
    DUK_ASSERT(end_offset <= DUK_UINT32_MAX);
 
    start_byte_offset = (duk_size_t) duk_heap_strcache_offset_char2byte(thr, h, (duk_uint_fast32_t) start_offset);
    end_byte_offset = (duk_size_t) duk_heap_strcache_offset_char2byte(thr, h, (duk_uint_fast32_t) end_offset);
 
    DUK_ASSERT(end_byte_offset >= start_byte_offset);
    DUK_ASSERT(end_byte_offset - start_byte_offset <= DUK_UINT32_MAX);  /* guaranteed by string limits */
 
    /* no size check is necessary */
    res = duk_heap_string_intern_checked(thr,
                                         DUK_HSTRING_GET_DATA(h) + start_byte_offset,
                                         (duk_uint32_t) (end_byte_offset - start_byte_offset));
 
    duk_push_hstring(ctx, res);
    duk_replace(ctx, index);
}
 
/* XXX: this is quite clunky.  Add Unicode helpers to scan backwards and
 * forwards with a callback to process codepoints?
 */
DUK_EXTERNAL void duk_trim(duk_context *ctx, duk_idx_t index) {
    duk_hthread *thr = (duk_hthread *) ctx;
    duk_hstring *h;
    const duk_uint8_t *p, *p_start, *p_end, *p_tmp1, *p_tmp2;  /* pointers for scanning */
    const duk_uint8_t *q_start, *q_end;  /* start (incl) and end (excl) of trimmed part */
    duk_codepoint_t cp;
 
    DUK_ASSERT_CTX_VALID(ctx);
 
    index = duk_require_normalize_index(ctx, index);
    h = duk_require_hstring(ctx, index);
    DUK_ASSERT(h != NULL);
 
    p_start = DUK_HSTRING_GET_DATA(h);
    p_end = p_start + DUK_HSTRING_GET_BYTELEN(h);
 
    p = p_start;
    while (p < p_end) {
        p_tmp1 = p;
        cp = (duk_codepoint_t) duk_unicode_decode_xutf8_checked(thr, &p_tmp1, p_start, p_end);
        if (!(duk_unicode_is_whitespace(cp) || duk_unicode_is_line_terminator(cp))) {
            break;
        }
        p = p_tmp1;
    }
    q_start = p;
    if (p == p_end) {
        /* entire string is whitespace */
        q_end = p;
        goto scan_done;
    }
 
    p = p_end;
    while (p > p_start) {
        p_tmp1 = p;
        while (p > p_start) {
            p--;
            if (((*p) & 0xc0) != 0x80) {
                break;
            }
        }
        p_tmp2 = p;
 
        cp = (duk_codepoint_t) duk_unicode_decode_xutf8_checked(thr, &p_tmp2, p_start, p_end);
        if (!(duk_unicode_is_whitespace(cp) || duk_unicode_is_line_terminator(cp))) {
            p = p_tmp1;
            break;
        }
    }
    q_end = p;
 
 scan_done:
    /* This may happen when forward and backward scanning disagree
     * (possible for non-extended-UTF-8 strings).
     */
    if (q_end < q_start) {
        q_end = q_start;
    }
 
    DUK_ASSERT(q_start >= p_start && q_start <= p_end);
    DUK_ASSERT(q_end >= p_start && q_end <= p_end);
    DUK_ASSERT(q_end >= q_start);
 
    DUK_DDD(DUK_DDDPRINT("trim: p_start=%p, p_end=%p, q_start=%p, q_end=%p",
                         (const void *) p_start, (const void *) p_end,
                         (const void *) q_start, (const void *) q_end));
 
    if (q_start == p_start && q_end == p_end) {
        DUK_DDD(DUK_DDDPRINT("nothing was trimmed: avoid interning (hashing etc)"));
        return;
    }
 
    duk_push_lstring(ctx, (const char *) q_start, (duk_size_t) (q_end - q_start));
    duk_replace(ctx, index);
}
 
DUK_EXTERNAL duk_codepoint_t duk_char_code_at(duk_context *ctx, duk_idx_t index, duk_size_t char_offset) {
    duk_hthread *thr = (duk_hthread *) ctx;
    duk_hstring *h;
    duk_ucodepoint_t cp;
 
    DUK_ASSERT_CTX_VALID(ctx);
 
    h = duk_require_hstring(ctx, index);
    DUK_ASSERT(h != NULL);
 
    DUK_ASSERT_DISABLE(char_offset >= 0);  /* always true, arg is unsigned */
    if (char_offset >= DUK_HSTRING_GET_CHARLEN(h)) {
        return 0;
    }
 
    DUK_ASSERT(char_offset <= DUK_UINT_MAX);  /* guaranteed by string limits */
    cp = duk_hstring_char_code_at_raw(thr, h, (duk_uint_t) char_offset);
    return (duk_codepoint_t) cp;
}