[glib] Bug 665685 â Add a #define for the max length of a Unicode decomposition

[Philip Withnall <pwithnall src gnome org>]

commit 3ac7c35656649b1d1fcf2ccaa670b854809d4cd8
Author: Philip Withnall <philip tecnocode co uk>
Date:   Tue Dec 6 18:30:43 2011 +0000

    Bug 665685 â Add a #define for the max length of a Unicode decomposition
    
    Add G_UNICHAR_MAX_DECOMPOSITION_LEN for the maximum length of the
    decomposition of a single Unicode character.
    
    Closes: bgo#665685

 glib/gunicode.h   |   12 ++++++++++++
 glib/gunidecomp.c |    4 ++--
 glib/guniprop.c   |    4 ++--
 3 files changed, 16 insertions(+), 4 deletions(-)
---
diff --git a/glib/gunicode.h b/glib/gunicode.h
index 213b38f..f89c07c 100644
--- a/glib/gunicode.h
+++ b/glib/gunicode.h
@@ -551,6 +551,18 @@ gsize g_unichar_fully_decompose (gunichar  ch,
                                  gunichar *result,
                                  gsize     result_len);
 
+/**
+ * G_UNICHAR_MAX_COMPAT_DECOMPOSITION_LEN:
+ *
+ * The maximum length (in codepoints) of a compatibility or canonical
+ * decomposition of a single Unicode character.
+ *
+ * This is as defined by Unicode 6.1.
+ *
+ * Since: 2.31.3
+ */
+#define G_UNICHAR_MAX_DECOMPOSITION_LEN 18 /* codepoints */
+
 /* Compute canonical ordering of a string in-place.  This rearranges
    decomposed characters in the string according to their combining
    classes.  See the Unicode manual for more information.  */
diff --git a/glib/gunidecomp.c b/glib/gunidecomp.c
index 6cbc2df..090b42d 100644
--- a/glib/gunidecomp.c
+++ b/glib/gunidecomp.c
@@ -700,8 +700,8 @@ g_unichar_compose (gunichar  a,
  * currently all decompositions are of length at most 4, but
  * this may change in the future (very unlikely though).
  * At any rate, Unicode does guarantee that a buffer of length
- * 18 is always enough for both compatibility and canonical
- * decompositions, so that is the size recommended.
+ * %G_UNICHAR_MAX_DECOMPOSITION_LEN is always enough for both compatibility and
+ * canonical decompositions, so that is the size recommended.
  *
  * See <ulink url="http://unicode.org/reports/tr15/";>UAX#15</ulink>
  * for details.
diff --git a/glib/guniprop.c b/glib/guniprop.c
index 8b139ae..5b818e3 100644
--- a/glib/guniprop.c
+++ b/glib/guniprop.c
@@ -855,9 +855,9 @@ real_toupper (const gchar *str,
 		   * which could simplify this considerably.
 		   */
 		  gsize decomp_len, i;
-		  gunichar decomp[18];
+		  gunichar decomp[G_UNICHAR_MAX_DECOMPOSITION_LEN];
 
-		  decomp_len = g_unichar_fully_decompose (c, FALSE, decomp, 18);
+		  decomp_len = g_unichar_fully_decompose (c, FALSE, decomp, G_N_ELEMENTS (decomp));
 		  for (i=0; i < decomp_len; i++)
 		    {
 		      if (decomp[i] != 0x307 /* COMBINING DOT ABOVE */)