20a9f99b3b
Detailed explanation in the code comments. Test: treehugger Change-Id: I2aef2510724c1c622b83e226b51d4c8429b88272
101 lines
3.5 KiB
C++
101 lines
3.5 KiB
C++
/*
|
|
* Copyright (C) 2017 The Android Open Source Project
|
|
* All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* * Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* * Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in
|
|
* the documentation and/or other materials provided with the
|
|
* distribution.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
|
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
|
|
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
|
|
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
|
|
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
|
|
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
|
|
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
|
|
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
|
|
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
|
|
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*/
|
|
|
|
#include <wchar.h>
|
|
|
|
#include "private/icu.h"
|
|
|
|
int wcwidth(wchar_t wc) {
|
|
// Fast-path ASCII.
|
|
if (wc >= 0x20 && wc < 0x7f) return 1;
|
|
|
|
// ASCII NUL is a special case.
|
|
if (wc == 0) return 0;
|
|
|
|
// C0.
|
|
if (wc < ' ' || (wc >= 0x7f && wc <= 0xa0)) return -1;
|
|
|
|
// Now for the i18n part. This isn't defined or standardized, so a lot of the choices are
|
|
// pretty arbitrary. See https://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c for more details.
|
|
|
|
// Fancy unicode control characters?
|
|
switch (__icu_charType(wc)) {
|
|
case -1:
|
|
// No icu4c available; give up.
|
|
return -1;
|
|
case U_CONTROL_CHAR:
|
|
return -1;
|
|
case U_NON_SPACING_MARK:
|
|
case U_ENCLOSING_MARK:
|
|
return 0;
|
|
case U_FORMAT_CHAR:
|
|
// A special case for soft hyphen (U+00AD) to match historical practice.
|
|
// See the tests for more commentary.
|
|
return (wc == 0x00ad) ? 1 : 0;
|
|
}
|
|
|
|
// Medial and final jamo render as zero width when used correctly,
|
|
// so we handle them specially rather than relying on East Asian Width.
|
|
switch (__icu_getIntPropertyValue(wc, UCHAR_HANGUL_SYLLABLE_TYPE)) {
|
|
case U_HST_VOWEL_JAMO:
|
|
case U_HST_TRAILING_JAMO:
|
|
return 0;
|
|
case U_HST_LEADING_JAMO:
|
|
case U_HST_LV_SYLLABLE:
|
|
case U_HST_LVT_SYLLABLE:
|
|
return 2;
|
|
}
|
|
|
|
// Hangeul choseong filler U+115F is default ignorable, so we check default
|
|
// ignorability only after we've already handled Hangeul jamo above.
|
|
if (__icu_hasBinaryProperty(wc, UCHAR_DEFAULT_IGNORABLE_CODE_POINT, nullptr)) return 0;
|
|
|
|
// A few weird special cases where EastAsianWidth is not helpful for us.
|
|
if (wc >= 0x3248 && wc <= 0x4dff) {
|
|
// Circled two-digit CJK "speed sign" numbers. EastAsianWidth is ambiguous,
|
|
// but wide makes more sense.
|
|
if (wc <= 0x324f) return 2;
|
|
// Hexagrams. EastAsianWidth is neutral, but wide seems better.
|
|
if (wc >= 0x4dc0) return 2;
|
|
}
|
|
|
|
// The EastAsianWidth property is at least defined by the Unicode standard!
|
|
// https://www.unicode.org/reports/tr11/
|
|
switch (__icu_getIntPropertyValue(wc, UCHAR_EAST_ASIAN_WIDTH)) {
|
|
case U_EA_AMBIGUOUS:
|
|
case U_EA_HALFWIDTH:
|
|
case U_EA_NARROW:
|
|
case U_EA_NEUTRAL:
|
|
return 1;
|
|
case U_EA_FULLWIDTH:
|
|
case U_EA_WIDE:
|
|
return 2;
|
|
}
|
|
|
|
return 0;
|
|
}
|