From c33cb60eb6e89b6af30fa9d576457ccefff74ad6 Mon Sep 17 00:00:00 2001
From: whythat <whythat@protonmail.com>
Date: Sun, 21 Jan 2018 17:28:32 +0200
Subject: common: implement dependent option descriptor

---
 src/common/command_line.h | 50 ++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 45 insertions(+), 5 deletions(-)

diff --git a/src/common/command_line.h b/src/common/command_line.h
index 7b183d86b..ddbb136e9 100644
--- a/src/common/command_line.h
+++ b/src/common/command_line.h
@@ -46,7 +46,7 @@ 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>
@@ -80,6 +80,22 @@ namespace command_line
     const char* description;
   };
 
+  template<typename T>
+  struct arg_descriptor<T, false, true>
+  {
+    typedef T value_type;
+
+    const char* name;
+    const char* description;
+
+    const arg_descriptor<bool, false>& ref;
+
+    T true_default_value;
+    T false_default_value;
+
+    bool not_use_default;
+  };
+
   template<typename T>
   boost::program_options::typed_value<T, char>* make_semantic(const arg_descriptor<T, true>& /*arg*/)
   {
@@ -95,6 +111,23 @@ namespace command_line
     return semantic;
   }
 
+  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) {
+      if (arg.ref.default_value)
+      {
+        semantic->default_value(arg.true_default_value);
+      }
+      else
+      {
+        semantic->default_value(arg.false_default_value);
+      }
+    }
+    return semantic;
+  }
+
   template<typename T>
   boost::program_options::typed_value<T, char>* make_semantic(const arg_descriptor<T, false>& arg, const T& def)
   {
@@ -112,8 +145,8 @@ 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 +222,19 @@ 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)
+  {
+    if (is_arg_defaulted(vm, arg) && !is_arg_defaulted(vm, arg.ref))
+      return get_arg(vm, arg.ref) ? arg.true_default_value : arg.false_default_value;
+    return 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)
-- 
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