lib: use ascii ctype utils

Use the new ascii ctype utils.

lib/message/mu-fields.cc

@@ -83,14 +83,16 @@ Field::xapian_term(const std::string& s) const
 	if (s.empty())
 		return res;
 
-	res.reserve(s.size() + 10);
-	/* slightly optimized common pure-ascii. */
-	if (G_LIKELY(g_str_is_ascii(s.c_str()))) {
-		res += s;
-		for (auto i = 1U; i != res.length(); ++i)
-			res[i] = g_ascii_tolower(res[i]);
-	} else
-		res += utf8_flatten(s);
+	res.reserve(s.size() + 1);
+	/* optimized common pure-ascii case */
+	for (auto&& c: s) {
+		if (G_UNLIKELY(!is_ascii(c))) { /* non-ascii after all */
+			res.erase(1U);
+			res += utf8_flatten(s);
+			break;
+		}
+		res.push_back(to_ascii_lower(c));
+	}
 
 	if (G_UNLIKELY(res.size() > MaxTermLength))
 		res.erase(MaxTermLength);

lib/message/mu-flags.hh

@@ -105,8 +105,7 @@ struct MessageFlagInfo {
 	 * @return lower-case shortcut
 	 */
 	constexpr char shortcut_lower() const {
-		return shortcut >= 'A' && shortcut <= 'Z' ?
-			shortcut +  ('a' - 'A') : shortcut;
+		return to_ascii_lower(shortcut);
 	}
 };
 

lib/message/mu-labels.cc

@@ -50,11 +50,11 @@ Mu::Labels::validate_label(const std::string &label)
 		if (g_unichar_isalnum(uc))
 			continue; // alphanum is okay
 
-		if (::iscntrl(uc))
+		if (is_ascii_cntrl(uc))
 			return Err(Error{Error::Code::InvalidArgument,
 					"control character {} not allowed in label",
 					static_cast<int>(uc)});
-		if (::isblank(uc))
+		if (is_ascii_blank(uc))
 			return Err(Error{Error::Code::InvalidArgument,
 					"blank character {} not allowed in label",
 					static_cast<int>(uc)});

lib/message/mu-message-part.cc

@@ -49,7 +49,8 @@ cook(const std::string& fname, const std::vector<char>& forbidden)
 	clean.reserve(fname.length());
 
 	for (auto& c: basename(fname))
-		if (seq_some(forbidden,[&](char fc){return ::iscntrl(c) || c == fc;}))
+		if (seq_some(forbidden,[&](char fc){
+			return is_ascii_cntrl(c) || c == fc;}))
 			clean += '-';
 		else
 			clean += c;