1 files changed, 123 insertions, 0 deletions
diff --git a/stdlib/grouping.h b/stdlib/grouping.h
new file mode 100644
index 0000000000..566f6a6109
--- /dev/null
+++ b/stdlib/grouping.h
@@ -0,0 +1,123 @@
+/* Internal header for proving correct grouping in strings of numbers.
+Copyright (C) 1995 Free Software Foundation, Inc.
+Contributed by Ulrich Drepper.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C Library 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
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+#include <limits.h>
+
+#ifndef MAX
+#define MAX(a,b)	({ typeof(a) _a = (a); typeof(b) _b = (b); \
+			   _a > _b ? _a : _b; })
+#endif
+
+/* Find the maximum prefix of the string between BEGIN and END which
+   satisfies the grouping rules.  It is assumed that at least one digit
+   follows BEGIN directly.  */
+
+static inline const char *
+correctly_grouped_prefix (const char *begin, const char *end,
+			  wchar_t thousands, const char *grouping)
+{
+  if (! grouping)
+    return end;
+
+  while (end > begin)
+    {
+      const char *cp = end - 1;
+      const char *gp = grouping;
+
+      /* Check first group.  */
+      while (cp >= begin && (wchar_t) *cp != thousands)
+	--cp;
+
+      if (end - cp == (int) *gp + 1)
+	{
+	  /* This group matches the specification.  */
+
+	  const char *new_end;
+
+	  if (cp < begin)
+	    /* There is just one complete group.  We are done.  */
+	    return end;
+
+	  /* CP points to a thousands separator character.  The preceding
+	     remainder of the string from BEGIN to NEW_END is the part we
+	     will consider if there is a grouping error in this trailing
+	     portion from CP to END.  */
+	  new_end = cp - 1;
+
+	  /* Loop while the grouping is correct.  */
+	  while (1)
+	    {
+	      /* Get the next grouping rule.  */
+	      ++gp;
+	      if (*gp == 0)
+		/* If end is reached use last rule.  */ 
+	        --gp;
+
+	      /* Skip the thousands separator.  */
+	      --cp;
+
+	      if (*gp == CHAR_MAX || *gp < 0)
+	        {
+	          /* No more thousands separators are allowed to follow.  */
+	          while (cp >= begin && (wchar_t) *cp != thousands)
+		    --cp;
+
+	          if (cp < begin)
+		    /* OK, only digits followed.  */
+		    return end;
+	        }
+	      else
+	        {
+		  /* Check the next group.  */
+	          const char *group_end = cp;
+
+		  while (cp >= begin && (wchar_t) *cp != thousands)
+		    --cp;
+
+		  if (cp < begin && group_end - cp <= (int) *gp)
+		    /* Final group is correct.  */
+		    return end;
+
+		  if (cp < begin || group_end - cp != (int) *gp)
+		    /* Incorrect group.  Punt.  */
+		    break;
+		}
+	    }
+
+	  /* The trailing portion of the string starting at NEW_END
+	     contains a grouping error.  So we will look for a correctly
+	     gouped number in the preceding portion instead.  */
+	  end = new_end;
+	}
+      else
+	{
+	  /* Even the first group was wrong; determine maximum shift.  */
+	  if (end - cp > (int) *gp + 1)
+	    end = cp + (int) *gp + 1;
+	  else if (cp < begin)
+	    /* This number does not fill the first group, but is correct.  */
+	    return end;
+	  else
+	    /* CP points to a thousands seperator character.  */
+	    end = cp;
+	}
+    }
+
+  return MAX (begin, end);
+}