query-parser: cleanup source string

Ensure there's no non-' ' whitespace, and no trailing/leading spaces.

lib/parser/tokenizer.cc

@@ -113,11 +113,29 @@ eat_token (std::string& food, size_t& pos)
 }
 
 
+static std::string
+cleanup (const std::string& dirty)
+{
+	auto clean = dirty;
+
+	// only accept spc as whitespace
+	for (auto f = clean.begin(); f != clean.end(); ++f)
+		if (*f < ' ')
+			*f = ' ';
+
+	clean.erase (0, clean.find_first_not_of(" "));
+	clean.erase (clean.find_last_not_of(" ") + 1); // remove trailing space
+
+	return clean;
+}
+
+
 Mux::Tokens
 Mux::tokenize (const std::string& s)
 {
 	Tokens tokens{};
-	std::string food{s};
+
+	std::string food = cleanup(s);
 	size_t pos{0};
 
 	if (s.empty())