Implement IRC format to xhtml-im conversion

The generated XML is very verbose because each IRC formatting tag makes us
close a <span/> element and reopen it with the new style applied.  However,
this works quite well and is easy to implement.

src/bridge/colors.hpp

@@ -1,20 +1,54 @@
 #ifndef COLORS_INCLUDED
 # define COLORS_INCLUDED
 
-#include <string>
-
 /**
- * A module handling the conversion between IRC colors and XHTML-IM, and vice versa.
+ * A module handling the conversion between IRC colors and XHTML-IM, and
+ * vice versa.
  */
 
-#define IRC_COLOR_BOLD_CHAR       '\x02'
-#define IRC_COLOR_COLOR_CHAR      '\x03'
-#define IRC_COLOR_RESET_CHAR      '\x0F'
-#define IRC_COLOR_FIXED_CHAR      '\x11'
-#define IRC_COLOR_REVERSE_CHAR    '\x12'
-#define IRC_COLOR_REVERSE2_CHAR   '\x16'
-#define IRC_COLOR_ITALIC_CHAR     '\x1D'
-#define IRC_COLOR_UNDERLINE_CHAR  '\x1F'
+#include <string>
+#include <memory>
+#include <tuple>
 
+class XmlNode;
+
+namespace Xmpp
+{
+// Contains:
+// - an XMPP-valid UTF-8 body
+// - an XML node representing the XHTML-IM body, or null
+  typedef std::tuple<const std::string, std::unique_ptr<XmlNode>> body;
+}
+
+#define IRC_FORMAT_BOLD_CHAR       '\x02' // done
+#define IRC_FORMAT_COLOR_CHAR      '\x03' // done
+#define IRC_FORMAT_RESET_CHAR      '\x0F' // done
+#define IRC_FORMAT_FIXED_CHAR      '\x11' // ??
+#define IRC_FORMAT_REVERSE_CHAR    '\x12' // maybe one day
+#define IRC_FORMAT_REVERSE2_CHAR   '\x16' // wat
+#define IRC_FORMAT_ITALIC_CHAR     '\x1D' // done
+#define IRC_FORMAT_UNDERLINE_CHAR  '\x1F' // done
+
+static const char irc_format_char[] = {
+  IRC_FORMAT_BOLD_CHAR,
+  IRC_FORMAT_COLOR_CHAR,
+  IRC_FORMAT_RESET_CHAR,
+  IRC_FORMAT_FIXED_CHAR,
+  IRC_FORMAT_REVERSE_CHAR,
+  IRC_FORMAT_REVERSE2_CHAR,
+  IRC_FORMAT_ITALIC_CHAR,
+  IRC_FORMAT_UNDERLINE_CHAR,
+  '\x00'
+};
+
+/**
+ * Convert the passed string into an XML tree representing the XHTML version
+ * of the message, converting the IRC colors symbols into xhtml-im
+ * formatting.
+ *
+ * Returns the body cleaned from any IRC formatting (but without any xhtml),
+ * and the body as XHTML-IM
+ */
+Xmpp::body irc_format_to_xhtmlim(const std::string& str);
 
 #endif // COLORS_INCLUDED