Bug 443206 – PANGO_SCRIPT_UNKNOWN should not cause a run break Patch

2007-06-02  Behdad Esfahbod  <behdad@gnome.org>

        Bug 443206 – PANGO_SCRIPT_UNKNOWN should not cause a run break
        Patch from Martin Hosken

        * pango/pango-script.c: Treat Unknown script like Common and other
        non-"real" scripts.


svn path=/branches/pango-1-16/; revision=2327

2 files changed, 98 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index 87243e01..fe2fd8ce 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2007-06-02  Behdad Esfahbod  <behdad@gnome.org>
+
+	Bug 443206 – PANGO_SCRIPT_UNKNOWN should not cause a run break
+	Patch from Martin Hosken
+
+	* pango/pango-script.c: Treat Unknown script like Common and other
+	non-"real" scripts.
+
 2007-05-10  Behdad Esfahbod  <behdad@gnome.org>
 
 	* ChangeLog.pre-1-16: Split ChangeLog.
diff --git a/pango/pango-script.c b/pango/pango-script.c
index 3036c999..5d93d826 100644
--- a/pango/pango-script.c
+++ b/pango/pango-script.c
@@ -257,7 +257,7 @@ get_pair_index (gunichar ch)
 }
 
 #define REAL_SCRIPT(script) \
-  ((script) > PANGO_SCRIPT_INHERITED)
+  ((script) > PANGO_SCRIPT_INHERITED && (script) != PANGO_SCRIPT_UNKNOWN)
 
 #define SAME_SCRIPT(script1, script2) \
   (!REAL_SCRIPT (script1) || !REAL_SCRIPT (script2) || (script1) == (script2))
@@ -380,6 +380,94 @@ pango_script_iter_next (PangoScriptIter *iter)
  * End of code from ICU
  **********************************************************/
 
+#include "pango-script-lang-table.h"
+
+/* The fact that this comparison function works is dependent
+ * on a property of the pango_script_lang_table which accidental rather
+ * than inherent.
+ *
+ * The property is if we take any element in the table and suffix it
+ * <elem>-<suffix> then that must strcmp() between any elements
+ * preceding the element in the table and any element following in the
+ * table. So, if we had something like:
+ *
+ * 'zh'
+ *' zh-cn'
+ *
+ * in the table we would have a problem since 'zh-tw' follows 'zh-cn'.
+ * On the other hand:
+ *
+ * 'zh'
+ * 'zha'
+ *
+ * Works because 'zh-tw' precedes 'zha'.
+ */
+static int
+script_for_lang_compare (gconstpointer key,
+			 gconstpointer member)
+{
+  PangoLanguage *lang = (PangoLanguage *)key;
+  const PangoScriptForLang *script_for_lang = member;
+
+  if (pango_language_matches (lang, script_for_lang->lang))
+    return 0;
+  else
+    return strcmp (pango_language_to_string (lang),
+		   script_for_lang->lang);
+}
+
+/**
+ * pango_language_includes_script:
+ * @language: a #PangoLanguage
+ * @script: a #PangoScript
+ *
+ * Determines if @script is one of the scripts used to
+ * write @language. The returned value is conservative;
+ * if nothing is known about the language tag @language,
+ * %TRUE will be returned, since, as far as Pango knows,
+ * @script might be used to write @language.
+ *
+ * This routine is used in Pango's itemization process when
+ * determining if a supplied language tag is relevant to
+ * a particular section of text. It probably is not useful for
+ * applications in most circumstances.
+ *
+ * Return value: %TRUE if @script is one of the scripts used
+ * to write @language, or if nothing is known about @language.
+ *
+ * Since: 1.4
+ **/
+gboolean
+pango_language_includes_script (PangoLanguage *language,
+				PangoScript    script)
+{
+  PangoScriptForLang *script_for_lang;
+  unsigned int j;
+
+  g_return_val_if_fail (language != NULL, FALSE);
+
+  if (!REAL_SCRIPT (script))
+    return TRUE;
+
+  /* This bsearch could be optimized to occur only once if
+   * we store the pointer to the PangoScriptForLang in the
+   * same block as the string value for the PangoLanguage.
+   */
+  script_for_lang = bsearch (pango_language_to_string (language),
+			     pango_script_for_lang,
+			     G_N_ELEMENTS (pango_script_for_lang),
+			     sizeof (PangoScriptForLang),
+			     script_for_lang_compare);
+  if (!script_for_lang)
+    return TRUE;
+
+  for (j = 0; j < G_N_ELEMENTS (script_for_lang->scripts); j++)
+    if (script_for_lang->scripts[j] == script)
+      return TRUE;
+
+  return FALSE;
+}
+
 /**
  * pango_script_get_sample_language:
  * @script: a #PangoScript
@@ -414,7 +502,7 @@ pango_script_get_sample_language (PangoScript script)
    * (Shavian for English, Osmanya for Somali, etc), typically
    * have no sample language
    */
-  static const char sample_languages[][4] = {
+  const char sample_languages[][4] = {
     "",    /* PANGO_SCRIPT_COMMON */
     "",    /* PANGO_SCRIPT_INHERITED */
     "ar",  /* PANGO_SCRIPT_ARABIC */