wcwidth.c

/*
 * This is an implementation of wcwidth() and wcswidth() as defined in
 * "The Single UNIX Specification, Version 2, The Open Group, 1997"
 * <http://www.UNIX-systems.org/online.html>
 *
 * Markus Kuhn -- 2000-02-08 -- public domain
 */

#include <wchar.h>

/* These functions define the column width of an ISO 10646 character
 * as follows:
 *
 *    - The null character (U+0000) has a column width of 0.
 *
 *    - Other C0/C1 control characters and DEL will lead to a return
 *      value of -1.
 *
 *    - Non-spacing and enclosing combining characters (general
 *      category code Mn or Me in the Unicode database) have a
 *      column width of 0.
 *
 *    - Spacing characters in the East Asian Wide (W) or East Asian
 *      FullWidth (F) category as defined in Unicode Technical
 *      Report #11 have a column width of 2.
 *
 *    - All remaining characters (including all printable
 *      ISO 8859-1 and WGL4 characters, Unicode control characters,
 *      etc.) have a column width of 1.
 *
 * This implementation assumes that wchar_t characters are encoded
 * in ISO 10646.
 */

int wcwidth(wchar_t ucs)
{
    /* sorted list of non-overlapping intervals of non-spacing characters */
    static const struct interval {
	unsigned short first;
	unsigned short last;
    } combining[] = {
	{
	0x0300, 0x034E}, {
	0x0360, 0x0362}, {
	0x0483, 0x0486}, {
	0x0488, 0x0489}, {
	0x0591, 0x05A1}, {
	0x05A3, 0x05B9}, {
	0x05BB, 0x05BD}, {
	0x05BF, 0x05BF}, {
	0x05C1, 0x05C2}, {
	0x05C4, 0x05C4}, {
	0x064B, 0x0655}, {
	0x0670, 0x0670}, {
	0x06D6, 0x06E4}, {
	0x06E7, 0x06E8}, {
	0x06EA, 0x06ED}, {
	0x0711, 0x0711}, {
	0x0730, 0x074A}, {
	0x07A6, 0x07B0}, {
	0x0901, 0x0902}, {
	0x093C, 0x093C}, {
	0x0941, 0x0948}, {
	0x094D, 0x094D}, {
	0x0951, 0x0954}, {
	0x0962, 0x0963}, {
	0x0981, 0x0981}, {
	0x09BC, 0x09BC}, {
	0x09C1, 0x09C4}, {
	0x09CD, 0x09CD}, {
	0x09E2, 0x09E3}, {
	0x0A02, 0x0A02}, {
	0x0A3C, 0x0A3C}, {
	0x0A41, 0x0A42}, {
	0x0A47, 0x0A48}, {
	0x0A4B, 0x0A4D}, {
	0x0A70, 0x0A71}, {
	0x0A81, 0x0A82}, {
	0x0ABC, 0x0ABC}, {
	0x0AC1, 0x0AC5}, {
	0x0AC7, 0x0AC8}, {
	0x0ACD, 0x0ACD}, {
	0x0B01, 0x0B01}, {
	0x0B3C, 0x0B3C}, {
	0x0B3F, 0x0B3F}, {
	0x0B41, 0x0B43}, {
	0x0B4D, 0x0B4D}, {
	0x0B56, 0x0B56}, {
	0x0B82, 0x0B82}, {
	0x0BC0, 0x0BC0}, {
	0x0BCD, 0x0BCD}, {
	0x0C3E, 0x0C40}, {
	0x0C46, 0x0C48}, {
	0x0C4A, 0x0C4D}, {
	0x0C55, 0x0C56}, {
	0x0CBF, 0x0CBF}, {
	0x0CC6, 0x0CC6}, {
	0x0CCC, 0x0CCD}, {
	0x0D41, 0x0D43}, {
	0x0D4D, 0x0D4D}, {
	0x0DCA, 0x0DCA}, {
	0x0DD2, 0x0DD4}, {
	0x0DD6, 0x0DD6}, {
	0x0E31, 0x0E31}, {
	0x0E34, 0x0E3A}, {
	0x0E47, 0x0E4E}, {
	0x0EB1, 0x0EB1}, {
	0x0EB4, 0x0EB9}, {
	0x0EBB, 0x0EBC}, {
	0x0EC8, 0x0ECD}, {
	0x0F18, 0x0F19}, {
	0x0F35, 0x0F35}, {
	0x0F37, 0x0F37}, {
	0x0F39, 0x0F39}, {
	0x0F71, 0x0F7E}, {
	0x0F80, 0x0F84}, {
	0x0F86, 0x0F87}, {
	0x0F90, 0x0F97}, {
	0x0F99, 0x0FBC}, {
	0x0FC6, 0x0FC6}, {
	0x102D, 0x1030}, {
	0x1032, 0x1032}, {
	0x1036, 0x1037}, {
	0x1039, 0x1039}, {
	0x1058, 0x1059}, {
	0x17B7, 0x17BD}, {
	0x17C6, 0x17C6}, {
	0x17C9, 0x17D3}, {
	0x18A9, 0x18A9}, {
	0x20D0, 0x20E3}, {
	0x302A, 0x302F}, {
	0x3099, 0x309A}, {
	0xFB1E, 0xFB1E}, {
	0xFE20, 0xFE23}
    };
    int min = 0;
    int max = sizeof(combining) / sizeof(struct interval) - 1;
    int mid;

    /* test for 8-bit control characters */
    if (ucs == 0)
	return 0;
    if (ucs < 32 || (ucs >= 0x7f && ucs < 0xa0))
	return -1;

    /* first quick check for Latin-1 etc. characters */
    if (ucs < combining[0].first)
	return 1;

    /* binary search in table of non-spacing characters */
    while (max >= min) {
	mid = (min + max) / 2;
	if (combining[mid].last < ucs)
	    min = mid + 1;
	else if (combining[mid].first > ucs)
	    max = mid - 1;
	else if (combining[mid].first <= ucs && combining[mid].last >= ucs)
	    return 0;
    }

    /* if we arrive here, ucs is not a combining or C0/C1 control character */

    /* fast test for majority of non-wide scripts */
    if (ucs < 0x1100)
	return 1;

    return 1 + ((ucs >= 0x1100 && ucs <= 0x115f) ||	/* Hangul Jamo */
		
		(ucs >= 0x2e80 && ucs <= 0xa4cf
		 && (ucs & ~0x0011) != 0x300a && ucs != 0x303f) ||	/* CJK ... Yi */
		(ucs >= 0xac00 && ucs <= 0xd7a3) ||	/* Hangul Syllables */
		(ucs >= 0xf900 && ucs <= 0xfaff) ||	/* CJK Compatibility Ideographs */
		(ucs >= 0xfe30 && ucs <= 0xfe6f) ||	/* CJK Compatibility Forms */
		(ucs >= 0xff00 && ucs <= 0xff5f) ||	/* Fullwidth Forms */
		(ucs >= 0xffe0 && ucs <= 0xffe6));
}


int wcswidth(const wchar_t * pwcs, size_t n)
{
    int w, width = 0;

    for (; *pwcs && n-- > 0; pwcs++)
	if ((w = wcwidth(*pwcs)) < 0)
	    return -1;
	else
	    width += w;

    return width;
}