Split up the 'linebreak' module.

[gnulib.git] / lib / unilbrk / u16-width-linebreaks.c

diff --git a/lib/unilbrk/u16-width-linebreaks.c b/lib/unilbrk/u16-width-linebreaks.c
new file mode 100644 (file)
index 0000000..6444559
--- /dev/null
+++ b/lib/unilbrk/u16-width-linebreaks.c
@@ -0,0 +1,108 @@
+/* Line breaking of UTF-16 strings.
+   Copyright (C) 2001-2003, 2006-2008 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2001.
+
+   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 <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include "unilbrk.h"
+
+#include "unistr.h"
+#include "uniwidth.h"
+
+int
+u16_width_linebreaks (const uint16_t *s, size_t n,
+                     int width, int start_column, int at_end_columns,
+                     const char *o, const char *encoding,
+                     char *p)
+{
+  const uint16_t *s_end;
+  char *last_p;
+  int last_column;
+  int piece_width;
+
+  u16_possible_linebreaks (s, n, encoding, p);
+
+  s_end = s + n;
+  last_p = NULL;
+  last_column = start_column;
+  piece_width = 0;
+  while (s < s_end)
+    {
+      ucs4_t uc;
+      int count = u16_mbtouc_unsafe (&uc, s, s_end - s);
+
+      /* Respect the override.  */
+      if (o != NULL && *o != UC_BREAK_UNDEFINED)
+       *p = *o;
+
+      if (*p == UC_BREAK_POSSIBLE || *p == UC_BREAK_MANDATORY)
+       {
+         /* An atomic piece of text ends here.  */
+         if (last_p != NULL && last_column + piece_width > width)
+           {
+             /* Insert a line break.  */
+             *last_p = UC_BREAK_POSSIBLE;
+             last_column = 0;
+           }
+       }
+
+      if (*p == UC_BREAK_MANDATORY)
+       {
+         /* uc is a line break character.  */
+         /* Start a new piece at column 0.  */
+         last_p = NULL;
+         last_column = 0;
+         piece_width = 0;
+       }
+      else
+       {
+         /* uc is not a line break character.  */
+         int w;
+
+         if (*p == UC_BREAK_POSSIBLE)
+           {
+             /* Start a new piece.  */
+             last_p = p;
+             last_column += piece_width;
+             piece_width = 0;
+             /* No line break for the moment, may be turned into
+                UC_BREAK_POSSIBLE later, via last_p. */
+           }
+
+         *p = UC_BREAK_PROHIBITED;
+
+         w = uc_width (uc, encoding);
+         if (w >= 0) /* ignore control characters in the string */
+           piece_width += w;
+       }
+
+      s += count;
+      p += count;
+      if (o != NULL)
+       o += count;
+    }
+
+  /* The last atomic piece of text ends here.  */
+  if (last_p != NULL && last_column + piece_width + at_end_columns > width)
+    {
+      /* Insert a line break.  */
+      *last_p = UC_BREAK_POSSIBLE;
+      last_column = 0;
+    }
+
+  return last_column + piece_width;
+}