diff options
Diffstat (limited to 'string.c')
-rw-r--r-- | string.c | 51 |
1 files changed, 51 insertions, 0 deletions
@@ -7137,6 +7137,57 @@ rb_str_is_ascii_only_p(VALUE str) return cr == ENC_CODERANGE_7BIT ? Qtrue : Qfalse; } +/** + * Shortens _str_ and adds three dots, an ellipsis, if it is longer + * than _len_ characters. + * + * \param str the string to ellipsize. + * \param len the maximum string length. + * \return the ellipsized string. + * \pre _len_ must not be negative. + * \post the length of the returned string in characters is less than or equal to _len_. + * \post If the length of _str_ is less than or equal _len_, returns _str_ itself. + * \post the encoded of returned string is equal to the encoded of _str_. + * \post the class of returned string is equal to the class of _str_. + * \note the length is counted in characters. + */ +VALUE +rb_str_ellipsize(VALUE str, long len) +{ + static const char ellipsis[] = "..."; + const long ellipsislen = sizeof(ellipsis) - 1; + rb_encoding *const enc = rb_enc_get(str); + const long blen = RSTRING_LEN(str); + const char *const p = RSTRING_PTR(str), *e = p + blen; + VALUE estr, ret = 0; + + if (len < 0) rb_raise(rb_eIndexError, "negative length %ld", len); + if (len * rb_enc_mbminlen(enc) >= blen || + (e = rb_enc_nth(p, e, len, enc)) - p == blen) { + ret = str; + } + else if (len <= ellipsislen || + !(e = rb_enc_step_back(p, e, e, len = ellipsislen, enc))) { + if (rb_enc_asciicompat(enc)) { + ret = rb_str_new_with_class(str, ellipsis, len); + rb_enc_associate(ret, enc); + } + else { + estr = rb_usascii_str_new(ellipsis, len); + ret = rb_str_encode(estr, rb_enc_from_encoding(enc), 0, Qnil); + } + } + else if (ret = rb_str_subseq(str, 0, e - p), rb_enc_asciicompat(enc)) { + rb_str_cat(ret, ellipsis, ellipsislen); + } + else { + estr = rb_str_encode(rb_usascii_str_new(ellipsis, ellipsislen), + rb_enc_from_encoding(enc), 0, Qnil); + rb_str_append(ret, estr); + } + return ret; +} + /********************************************************************** * Document-class: Symbol * |