Added the check_sub_option() method to the command line parser check

object.

dlib/cmd_line_parser/cmd_line_parser_check_1.h

@@ -3,7 +3,7 @@
 #ifndef DLIB_CMD_LINE_PARSER_CHECk_1_
 #define DLIB_CMD_LINE_PARSER_CHECk_1_ 
 
-#include "cmd_line_parser_kernel_abstract.h"
+#include "cmd_line_parser_check_abstract.h"
 #include <sstream>
 #include <string>
 #include "../string.h"
@@ -191,6 +191,11 @@ namespace dlib
             const string_type& option_name2
         ) const;
 
+        void check_sub_option (
+            const string_type& parent_option,
+            const string_type& sub_option
+        ) const;
+
         template <
             size_t length
             >
@@ -423,6 +428,27 @@ namespace dlib
         }
     }
 
+// ----------------------------------------------------------------------------------------
+
+    template <typename clp_base>
+    void cmd_line_parser_check_1<clp_base>::
+    check_sub_option (
+        const string_type& parent_option,
+        const string_type& sub_option
+    ) const
+    {
+        if (this->option(parent_option).count() == 0)
+        {
+            if (this->option(sub_option).count() != 0)
+            {
+                std::vector<string_type> vect;
+                vect.resize(1);
+                vect[0] = parent_option;
+                throw cmd_line_check_error( EMISSING_REQUIRED_OPTION, sub_option, vect);
+            }
+        }
+    }
+
 // ----------------------------------------------------------------------------------------
 
     template <typename clp_base>

dlib/cmd_line_parser/cmd_line_parser_check_abstract.h

@@ -217,6 +217,28 @@ namespace dlib
                         - opt2 == The next incompatible option found.
         !*/
 
+        void check_sub_option (
+            const string_type& parent_option,
+            const string_type& sub_option
+        ) const;
+        /*!
+            requires
+                - parsed_line() == true
+                - option_is_defined(parent_option) == true
+                - option_is_defined(sub_option) == true
+            ensures
+                - if (option(parent_option).count() == 0) then
+                    - option(sub_option).count() == 0
+            throws
+                - std::bad_alloc
+                - cmd_line_check_error
+                    This exception is thrown if the ensures clause could not be satisfied.
+                    The exception's members will be set as follows:
+                        - type == EMISSING_REQUIRED_OPTION 
+                        - opt == sub_option. 
+                        - required_opts == a vector that contains only parent_option. 
+        !*/
+
         template <
             size_t length
             >

dlib/cmd_line_parser/cmd_line_parser_check_c.h

@@ -75,6 +75,11 @@ namespace dlib
             const string_type& option_name2
         ) const;
 
+        void check_sub_option (
+            const string_type& parent_option,
+            const string_type& sub_option
+        ) const;
+
         template <
             size_t length
             >
@@ -266,6 +271,30 @@ namespace dlib
         clp_check::check_incompatible_options(option_name1,option_name2);
     }
 
+// ----------------------------------------------------------------------------------------
+
+    template <typename clp_check>
+    void cmd_line_parser_check_c<clp_check>::
+    check_sub_option (
+        const string_type& parent_option,
+        const string_type& sub_option
+    ) const
+    {
+        // make sure requires clause is not broken
+        DLIB_CASSERT( this->parsed_line() == true && this->option_is_defined(parent_option) &&
+                      this->option_is_defined(sub_option), 
+                 "\tvoid cmd_line_parser_check::check_sub_option()"
+                 << "\n\tSee the requires clause for this function."
+                 << "\n\tthis:                             " << this
+                 << "\n\tparsed_line():                    " << this->parsed_line()
+                 << "\n\toption_is_defined(parent_option): " << this->option_is_defined(parent_option)
+                 << "\n\toption_is_defined(sub_option):    " << this->option_is_defined(sub_option)
+                 << "\n\tparent_option:                    " << parent_option 
+                 << "\n\tsub_option:                       " << sub_option 
+        );
+        clp_check::check_sub_option(parent_option,sub_option);
+    }
+
 // ----------------------------------------------------------------------------------------
 
     template <typename clp_check>