Refactor regex and implement UTF8 mode for GRegex

- with non-unicode byte to Private Use Area A mapping
- move all ifdefs to iregex.h file only

src/core/iregex.h

@@ -0,0 +1,52 @@
+#ifndef __REGEX_H
+#define __REGEX_H
+
+#include "common.h"
+
+#ifdef USE_GREGEX
+
+#include <glib.h>
+typedef	GRegex Regex;
+typedef	GMatchInfo MatchInfo;
+
+#define i_match_info_matches g_match_info_matches
+#define i_match_info_free g_match_info_free
+
+#else
+
+#include <regex.h>
+typedef	regex_t Regex;
+typedef regmatch_t MatchInfo;
+
+gboolean
+i_match_info_matches (const MatchInfo *match_info);
+
+void
+i_match_info_free (MatchInfo *match_info);
+
+#endif
+
+Regex *
+i_regex_new (const gchar *pattern,
+             GRegexCompileFlags compile_options,
+             GRegexMatchFlags match_options,
+             GError **error);
+
+void
+i_regex_unref (Regex *regex);
+
+gboolean
+i_regex_match (const Regex *regex,
+               const gchar *string,
+               GRegexMatchFlags match_options,
+               MatchInfo **match_info,
+               const gchar **new_string);
+
+gboolean
+i_match_info_fetch_pos (const MatchInfo *match_info,
+                        gint match_num,
+                        gint *start_pos,
+                        gint *end_pos,
+                        const gchar *new_string);
+
+#endif