1 files changed, 42 insertions, 5 deletions
diff --git a/src/common/command_line.h b/src/common/command_line.h
index 7b183d86b..f67efcf86 100644
--- a/src/common/command_line.h
+++ b/src/common/command_line.h
@@ -30,7 +30,9 @@
 
 #pragma once
 
+#include <functional>
 #include <iostream>
+#include <sstream>
 #include <type_traits>
 
 #include <boost/program_options/parsers.hpp>
@@ -46,7 +48,7 @@ namespace command_line
   //! \return True if `str` is `is_iequal("n" || "no" || `tr("no"))`.
   bool is_no(const std::string& str);
 
-  template<typename T, bool required = false>
+  template<typename T, bool required = false, bool dependent = false>
   struct arg_descriptor;
 
   template<typename T>
@@ -81,6 +83,22 @@ namespace command_line
   };
 
   template<typename T>
+  struct arg_descriptor<T, false, true>
+  {
+    typedef T value_type;
+
+    const char* name;
+    const char* description;
+
+    T default_value;
+
+    const arg_descriptor<bool, false>& ref;
+    std::function<T(bool, bool, T)> depf;
+
+    bool not_use_default;
+  };
+
+  template<typename T>
   boost::program_options::typed_value<T, char>* make_semantic(const arg_descriptor<T, true>& /*arg*/)
   {
     return boost::program_options::value<T>()->required();
@@ -96,6 +114,20 @@ namespace command_line
   }
 
   template<typename T>
+  boost::program_options::typed_value<T, char>* make_semantic(const arg_descriptor<T, false, true>& arg)
+  {
+    auto semantic = boost::program_options::value<T>();
+    if (!arg.not_use_default) {
+      std::ostringstream format;
+      format << arg.depf(false, true, arg.default_value) << ", "
+             << arg.depf(true, true, arg.default_value) << " if '"
+             << arg.ref.name << "'";
+      semantic->default_value(arg.depf(arg.ref.default_value, true, arg.default_value), format.str());
+    }
+    return semantic;
+  }
+
+  template<typename T>
   boost::program_options::typed_value<T, char>* make_semantic(const arg_descriptor<T, false>& arg, const T& def)
   {
     auto semantic = boost::program_options::value<T>();
@@ -112,8 +144,8 @@ namespace command_line
     return semantic;
   }
 
-  template<typename T, bool required>
-  void add_arg(boost::program_options::options_description& description, const arg_descriptor<T, required>& arg, bool unique = true)
+  template<typename T, bool required, bool dependent>
+  void add_arg(boost::program_options::options_description& description, const arg_descriptor<T, required, dependent>& arg, bool unique = true)
   {
     if (0 != description.find_nothrow(arg.name, false))
     {
@@ -189,12 +221,17 @@ namespace command_line
     return !value.empty();
   }
 
-  template<typename T, bool required>
-  bool is_arg_defaulted(const boost::program_options::variables_map& vm, const arg_descriptor<T, required>& arg)
+  template<typename T, bool required, bool dependent>
+  bool is_arg_defaulted(const boost::program_options::variables_map& vm, const arg_descriptor<T, required, dependent>& arg)
   {
     return vm[arg.name].defaulted();
   }
 
+  template<typename T, bool required>
+  T get_arg(const boost::program_options::variables_map& vm, const arg_descriptor<T, required, true>& arg)
+  {
+    return arg.depf(get_arg(vm, arg.ref), is_arg_defaulted(vm, arg), vm[arg.name].template as<T>());
+  }
 
   template<typename T, bool required>
   T get_arg(const boost::program_options::variables_map& vm, const arg_descriptor<T, required>& arg)