Can now test for an option being set in optionst

There was previously no public interface to check whether an option had
been set in an optionst object; this meant that clients were instead
using the isset() method of cmdlinet. This change allows us to set the
options from the cmdlinet near the beginning of the front-end, and not
refer to the cmdlinet afterward.

Author: karkhaz

src/util/options.cpp

@@ -57,6 +57,11 @@ unsigned int optionst::get_unsigned_int_option(const std::string &option) const
   return value.empty()?0:safe_string2unsigned(value);
 }
 
+bool optionst::is_set(const std::string &option) const
+{
+  return option_map.find(option) != option_map.end();
+}
+
 const std::string optionst::get_option(const std::string &option) const
 {
   option_mapt::const_iterator it=

src/util/options.h

@@ -28,6 +28,9 @@ class optionst
   unsigned int get_unsigned_int_option(const std::string &option) const;
   const value_listt &get_list_option(const std::string &option) const;
 
+  /// N.B. opts.is_set("foo") does not imply opts.get_bool_option("foo")
+  bool is_set(const std::string &option) const;
+
   void set_option(const std::string &option, const bool value);
   void set_option(const std::string &option, const int value);
   void set_option(const std::string &option, const unsigned value);