| /* Case-mapping context of prefix UTF-8/UTF-16/UTF-32 string. |
| Copyright (C) 2009-2020 Free Software Foundation, Inc. |
| Written by Bruno Haible <bruno@clisp.org>, 2009. |
| |
| This program is free software: you can redistribute it and/or modify it |
| under the terms of the GNU Lesser General Public License as published |
| by the Free Software Foundation; either version 3 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public License |
| along with this program. If not, see <https://www.gnu.org/licenses/>. */ |
| |
| casing_prefix_context_t |
| FUNC1 (const UNIT *s, size_t n) |
| { |
| return FUNC2 (s, n, unicase_empty_prefix_context); |
| } |
| |
| casing_prefix_context_t |
| FUNC2 (const UNIT *s, size_t n, casing_prefix_context_t a_context) |
| { |
| #if 0 |
| /* Forward iteration. Slow for long strings. */ |
| casing_prefix_context_t context = a_context; |
| const UNIT *s_end = s + n; |
| |
| while (s < s_end) |
| { |
| ucs4_t uc; |
| int count = U_MBTOUC_UNSAFE (&uc, s, s_end - s); |
| |
| if (!uc_is_case_ignorable (uc)) |
| context.last_char_except_ignorable = uc; |
| |
| { |
| int ccc = uc_combining_class (uc); |
| if (ccc == UC_CCC_A || ccc == UC_CCC_NR) |
| context.last_char_normal_or_above = uc; |
| } |
| |
| s += count; |
| } |
| |
| return context; |
| #else |
| /* Iterate backwards, only as far as needed. */ |
| casing_prefix_context_t context; |
| ucs4_t last_char_except_ignorable = (ucs4_t)(-1); |
| ucs4_t last_char_normal_or_above = (ucs4_t)(-1); |
| const UNIT *p = s + n; |
| |
| for (;;) |
| { |
| ucs4_t uc; |
| p = U_PREV (&uc, p, s); |
| if (p == NULL) |
| break; |
| |
| if (last_char_except_ignorable == (ucs4_t)(-1)) |
| { |
| if (!uc_is_case_ignorable (uc)) |
| last_char_except_ignorable = uc; |
| } |
| |
| if (last_char_normal_or_above == (ucs4_t)(-1)) |
| { |
| int ccc = uc_combining_class (uc); |
| if (ccc == UC_CCC_A || ccc == UC_CCC_NR) |
| last_char_normal_or_above = uc; |
| } |
| |
| if (last_char_except_ignorable != (ucs4_t)(-1) |
| && last_char_normal_or_above != (ucs4_t)(-1)) |
| break; |
| } |
| context.last_char_except_ignorable = |
| (last_char_except_ignorable != (ucs4_t)(-1) |
| ? last_char_except_ignorable |
| : a_context.last_char_except_ignorable); |
| context.last_char_normal_or_above = |
| (last_char_normal_or_above != (ucs4_t)(-1) |
| ? last_char_normal_or_above |
| : a_context.last_char_normal_or_above); |
| |
| return context; |
| #endif |
| } |