#include "configuration.h"
#include "utf8.h"
#include "vector.h"
+#include "unidata.h"
/** @brief Low-level converstion routine
* @param from Source encoding
else return 0;
}
+/** @brief Return nonzero if @p c is a combining character */
+static int combining(int c) {
+ if(c < UNICODE_NCHARS) {
+ const struct unidata *const ud = &unidata[c / 256][c % 256];
+
+ return ud->gc == unicode_gc_Mn || ud->ccc != 0;
+ }
+ /* Assume unknown characters are noncombining */
+ return 0;
+}
+
+/** @brief Truncate a string for display purposes
+ * @param s Pointer to UTF-8 string
+ * @param max Maximum number of columns
+ * @return @p or truncated string (never NULL)
+ *
+ * We don't correctly support bidi or double-width characters yet, nor
+ * locate default grapheme cluster boundaries for saner truncation.
+ */
+const char *truncate_for_display(const char *s, long max) {
+ const char *t = s, *r, *cut = 0;
+ char *truncated;
+ uint32_t c;
+ long n = 0;
+
+ /* We need to discover two things: firstly whether the string is
+ * longer than @p max glyphs and secondly if it is not, where to cut
+ * the string.
+ *
+ * Combining characters follow their base character (unicode
+ * standard 5.0 s2.11), so after each base character we must
+ */
+ while(*t) {
+ PARSE_UTF8(t, c, return s);
+ if(combining(c))
+ /* This must be an initial combining character. We just skip it. */
+ continue;
+ /* So c must be a base character. It may be followed by any
+ * number of combining characters. We advance past them. */
+ do {
+ r = t;
+ PARSE_UTF8(t, c, return s);
+ } while(combining(c));
+ /* Last character wasn't a combining character so back up */
+ t = r;
+ ++n;
+ /* So now there are N glyphs before position T. We might
+ * therefore have reached the cut position. */
+ if(n == max - 3)
+ cut = t;
+ }
+ /* If the string is short enough we return it unmodified */
+ if(n < max)
+ return s;
+ truncated = xmalloc_noptr(cut - s + 4);
+ memcpy(truncated, s, cut - s);
+ strcpy(truncated + (cut - s), "...");
+ return truncated;
+}
+
/*
Local Variables:
c-basic-offset:2