New module 'unicase/u8-suffix-context'.

[gnulib.git] / lib / unicase / u-suffix-context.h

diff --git a/lib/unicase/u-suffix-context.h b/lib/unicase/u-suffix-context.h
new file mode 100644 (file)
index 0000000..96c58da
--- /dev/null
+++ b/lib/unicase/u-suffix-context.h
@@ -0,0 +1,90 @@
+/* Case-mapping context of suffix UTF-8/UTF-16/UTF-32 string.
+   Copyright (C) 2009 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2009.
+
+   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/>.  */
+
+casing_suffix_context_t
+FUNC1 (const UNIT *s, size_t n)
+{
+  return FUNC2 (s, n, unicase_empty_suffix_context);
+}
+
+casing_suffix_context_t
+FUNC2 (const UNIT *s, size_t n, casing_suffix_context_t a_context)
+{
+  casing_suffix_context_t context;
+  /* Evaluate all three conditions in a single pass through the string S.
+     The three variables are -1 as long as the value of the condition has
+     not been determined.  */
+  int scc_FINAL_SIGMA = -1;
+  int scc_MORE_ABOVE = -1;
+  int scc_BEFORE_DOT = -1;
+  const UNIT *s_end = s + n;
+
+  while (s < s_end)
+    {
+      ucs4_t uc;
+      int count = U_MBTOUC_UNSAFE (&uc, s, s_end - s);
+
+      if (scc_FINAL_SIGMA < 0)
+       {
+         if (uc_is_cased (uc))
+           scc_FINAL_SIGMA = SCC_FINAL_SIGMA_MASK;
+         else if (!uc_is_case_ignorable (uc))
+           scc_FINAL_SIGMA = 0;
+       }
+
+      if (scc_MORE_ABOVE < 0)
+       {
+         int ccc = uc_combining_class (uc);
+         if (ccc == UC_CCC_A)
+           scc_MORE_ABOVE = SCC_MORE_ABOVE_MASK;
+         else if (ccc == UC_CCC_NR)
+           scc_MORE_ABOVE = 0;
+       }
+
+      if (scc_BEFORE_DOT < 0)
+       {
+         if (uc == 0x0307) /* COMBINING DOT ABOVE */
+           scc_BEFORE_DOT = SCC_BEFORE_DOT_MASK;
+         else
+           {
+             int ccc = uc_combining_class (uc);
+             if (ccc == UC_CCC_A || ccc == UC_CCC_NR)
+               scc_BEFORE_DOT = 0;
+           }
+       }
+
+      if ((scc_FINAL_SIGMA | scc_MORE_ABOVE | scc_BEFORE_DOT) >= 0)
+       /* All conditions have been determined.  */
+       break;
+
+      s += count;
+    }
+
+  /* For those conditions that have not been determined so far, use the
+     value from the argument context.  */
+  context.bits =
+    (scc_FINAL_SIGMA >= 0
+     ? scc_FINAL_SIGMA
+     : a_context.bits & SCC_FINAL_SIGMA_MASK)
+    | (scc_MORE_ABOVE >= 0
+       ? scc_MORE_ABOVE
+       : a_context.bits & SCC_MORE_ABOVE_MASK)
+    | (scc_BEFORE_DOT >= 0
+       ? scc_BEFORE_DOT
+       : a_context.bits & SCC_BEFORE_DOT_MASK);
+  return context;
+}