[gitg] Add Gitg.Convert utility

[Jesse van den Kieboom <jessevdk src gnome org>]

commit a4346312723cec01577a7b2e92e4487f44860fa6
Author: Jesse van den Kieboom <jessevdk gnome org>
Date:   Tue Dec 22 09:56:47 2015 +0100

    Add Gitg.Convert utility

 gitg/Makefile.am       |    1 +
 gitg/gitg-convert.vala |  138 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 139 insertions(+), 0 deletions(-)
---
diff --git a/gitg/Makefile.am b/gitg/Makefile.am
index e241f93..44e2f41 100644
--- a/gitg/Makefile.am
+++ b/gitg/Makefile.am
@@ -65,6 +65,7 @@ gitg_gitg_VALASOURCES =                                               \
        gitg/gitg-commit-action-create-patch.vala               \
        gitg/gitg-commit-action-create-tag.vala                 \
        gitg/gitg-commit-action-cherry-pick.vala                \
+       gitg/gitg-convert.vala                                  \
        gitg/gitg-create-branch-dialog.vala                     \
        gitg/gitg-create-tag-dialog.vala                        \
        gitg/gitg-dash-view.vala                                \
diff --git a/gitg/gitg-convert.vala b/gitg/gitg-convert.vala
new file mode 100644
index 0000000..fad75d3
--- /dev/null
+++ b/gitg/gitg-convert.vala
@@ -0,0 +1,138 @@
+/*
+ * This file is part of gitg
+ *
+ * Copyright (C) 2015 - Jesse van den Kieboom
+ *
+ * gitg is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * gitg 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with gitg. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+namespace Gitg.Convert
+{
+       private void utf8_validate_fallback(ref string text, ssize_t size)
+       {
+               char *end;
+
+               while (!text.validate(size, out end))
+               {
+                       *end = '?';
+               }
+       }
+
+       private string convert_fallback(string text, ssize_t size, string fallback)
+       {
+               string res = "";
+               size_t read;
+
+               var str = new StringBuilder();
+
+               while (true)
+               {
+                       try
+                       {
+                               res = GLib.convert(text, size, "UTF-8", "ASCII", out read);
+                               break;
+                       }
+                       catch
+                       {
+                               try
+                               {
+                                       str.append(GLib.convert(text, (ssize_t)read, "UTF-8", "ASCII"));
+                               } catch {}
+
+                               str.append(fallback);
+
+                               text = (string)((uint8[])text)[(read + 1):size];
+                               size -= (ssize_t)read;
+                       }
+               }
+
+               str.append(res);
+
+               var retval = str.str;
+               Convert.utf8_validate_fallback(ref retval, str.len);
+
+               return retval;
+       }
+
+       private bool convert_and_check(string text, ssize_t size, string from_charset, out string? ret)
+       {
+               size_t read, written;
+
+               ret = null;
+
+               try
+               {
+                       ret = GLib.convert(text, size, "UTF-8", from_charset, out read, out written);
+
+                       if (read == size)
+                       {
+                               Convert.utf8_validate_fallback(ref ret, (ssize_t)written);
+                               return true;
+                       }
+               }
+               catch {}
+
+               return false;
+       }
+
+
+       public string utf8(string str, ssize_t size = -1, string? from_charset = null)
+       {
+               if (size == -1)
+               {
+                       size = str.length;
+               }
+
+               if (from_charset == null)
+               {
+                       if (str.validate(size))
+                       {
+                               return str[0:size];
+                       }
+               }
+               else
+               {
+                       string ret;
+
+                       if (from_charset.ascii_casecmp("UTF-8") == 0)
+                       {
+                               ret = str[0:size];
+                               Convert.utf8_validate_fallback(ref ret, size);
+
+                               return ret;
+                       }
+
+                       if (Convert.convert_and_check(str, size, from_charset, out ret))
+                       {
+                               return ret;
+                       }
+               }
+
+               string locale_charset;
+
+               if (!GLib.get_charset(out locale_charset))
+               {
+                       string ret;
+
+                       if (Convert.convert_and_check(str, size, locale_charset, out ret))
+                       {
+                               return ret;
+                       }
+               }
+
+               return Convert.convert_fallback(str, size, "?");
+       }
+}
+
+/* ex:set ts=4 noet: */