Add support for tracking argument/option position

The scanner interface now provides the position() function that returns
a monotonically-increasing number which, if stored, can later be used to
determine the relative position of the arguments.

There is also now a parser implementation for std::pair<T, std::size_t>
which parses the value T into the first half of the pair and stores the
option position in the second half.

Together, this can be used to establish the relative position of different
options, for example:

class options
{
  std::vector<std::pair<std::uint64_t, std::size>> --config-id;
  std::vector<std::pair<std::string,   std::size>> --config-name;
};

cli::argv_scanner scan (argc, argv);
options ops (scan);

// Iterate over --config-id and --config-name options in the order
// specified by the user.
//
auto ii (ops.config_id ().begin ());
auto ni (ops.config_name ().begin ());

for (size_t i (0), n (scan.position ()); i != n; ++i)
{
  if (ii != ops.config_id ().end () && ii->second == i)
  {
    // Handle *ii.
    ++ii;
  }

  if (ni != ops.config_name ().end () && ni->second == i)
  {
    // Handle *ni.
    ++ni;
  }
}

1 files changed, 43 insertions, 20 deletions

diff --git a/cli/cli/runtime-inline.cxx b/cli/cli/runtime-inline.cxx
index 8f0e84c..e3dce1b 100644
--- a/cli/cli/runtime-inline.cxx
+++ b/cli/cli/runtime-inline.cxx
@@ -232,14 +232,29 @@ generate_runtime_inline (context& ctx)
      << "//" << endl;
 
   os << inl << "argv_scanner::" << endl
-     << "argv_scanner (int& argc, char** argv, bool erase)" << endl
-     << ": i_ (1), argc_ (argc), argv_ (argv), erase_ (erase)"
+     << "argv_scanner (int& argc," << endl
+     << "char** argv," << endl
+     << "bool erase," << endl
+     << "std::size_t sp)" << endl
+     << ": start_position_ (sp + 1)," << endl
+     << "  i_ (1)," << endl
+     << "  argc_ (argc)," << endl
+     << "  argv_ (argv)," << endl
+     << "  erase_ (erase)"
      << "{"
      << "}";
 
   os << inl << "argv_scanner::" << endl
-     << "argv_scanner (int start, int& argc, char** argv, bool erase)" << endl
-     << ": i_ (start), argc_ (argc), argv_ (argv), erase_ (erase)"
+     << "argv_scanner (int start," << endl
+     << "int& argc," << endl
+     << "char** argv," << endl
+     << "bool erase," << endl
+     << "std::size_t sp)" << endl
+     << ": start_position_ (sp + static_cast<std::size_t> (start))," << endl
+     << "  i_ (start)," << endl
+     << "  argc_ (argc)," << endl
+     << "  argv_ (argv)," << endl
+     << "  erase_ (erase)"
      << "{"
      << "}";
 
@@ -257,9 +272,10 @@ generate_runtime_inline (context& ctx)
        << "//" << endl;
 
     os << inl << "vector_scanner::" << endl
-       << "vector_scanner (const std::vector<std::string>& v, " <<
-      "std::size_t i)" << endl
-       << ": v_ (v), i_ (i)"
+       << "vector_scanner (const std::vector<std::string>& v," << endl
+       << "std::size_t i," << endl
+       << "std::size_t sp)" << endl
+       << ": start_position_ (sp), v_ (v), i_ (i)"
        << "{"
        << "}";
 
@@ -270,9 +286,10 @@ generate_runtime_inline (context& ctx)
        << "}";
 
     os << inl << "void vector_scanner::" << endl
-       << "reset (std::size_t i)"
+       << "reset (std::size_t i, std::size_t sp)"
        << "{"
        << "i_ = i;"
+       << "start_position_ = sp;"
        << "}";
   }
 
@@ -289,8 +306,9 @@ generate_runtime_inline (context& ctx)
        << "argv_file_scanner (int& argc," << endl
        << "char** argv," << endl
        << "const std::string& option," << endl
-       << "bool erase)" << endl
-       << ": argv_scanner (argc, argv, erase)," << endl
+       << "bool erase," << endl
+       << "std::size_t sp)" << endl
+       << ": argv_scanner (argc, argv, erase, sp)," << endl
        << "  option_ (option)," << endl
        << "  options_ (&option_info_)," << endl
        << "  options_count_ (1)," << endl
@@ -308,8 +326,9 @@ generate_runtime_inline (context& ctx)
        << "int& argc," << endl
        << "char** argv," << endl
        << "const std::string& option," << endl
-       << "bool erase)" << endl
-       << ": argv_scanner (start, argc, argv, erase)," << endl
+       << "bool erase," << endl
+       << "std::size_t sp)" << endl
+       << ": argv_scanner (start, argc, argv, erase, sp)," << endl
        << "  option_ (option)," << endl
        << "  options_ (&option_info_)," << endl
        << "  options_count_ (1)," << endl
@@ -324,8 +343,9 @@ generate_runtime_inline (context& ctx)
 
     os << inl << "argv_file_scanner::" << endl
        << "argv_file_scanner (const std::string& file," << endl
-       << "const std::string& option)" << endl
-       << ": argv_scanner (0, zero_argc_, 0)," << endl
+       << "const std::string& option," << endl
+       << "std::size_t sp)" << endl
+       << ": argv_scanner (0, zero_argc_, 0, sp)," << endl
        << "  option_ (option)," << endl
        << "  options_ (&option_info_)," << endl
        << "  options_count_ (1)," << endl
@@ -345,8 +365,9 @@ generate_runtime_inline (context& ctx)
        << "char** argv," << endl
        << "const option_info* options," << endl
        << "std::size_t options_count," << endl
-       << "bool erase)" << endl
-       << ": argv_scanner (argc, argv, erase)," << endl
+       << "bool erase," << endl
+       << "std::size_t sp)" << endl
+       << ": argv_scanner (argc, argv, erase, sp)," << endl
        << "  options_ (options)," << endl
        << "  options_count_ (options_count)," << endl
        << "  i_ (1)";
@@ -362,8 +383,9 @@ generate_runtime_inline (context& ctx)
        << "char** argv," << endl
        << "const option_info* options," << endl
        << "std::size_t options_count," << endl
-       << "bool erase)" << endl
-       << ": argv_scanner (start, argc, argv, erase)," << endl
+       << "bool erase," << endl
+       << "std::size_t sp)" << endl
+       << ": argv_scanner (start, argc, argv, erase, sp)," << endl
        << "  options_ (options)," << endl
        << "  options_count_ (options_count)," << endl
        << "  i_ (1)";
@@ -376,8 +398,9 @@ generate_runtime_inline (context& ctx)
     os << inl << "argv_file_scanner::" << endl
        << "argv_file_scanner (const std::string& file," << endl
        << "const option_info* options," << endl
-       << "std::size_t options_count)" << endl
-       << ": argv_scanner (0, zero_argc_, 0)," << endl
+       << "std::size_t options_count," << endl
+       << "std::size_t sp)" << endl
+       << ": argv_scanner (0, zero_argc_, 0, sp)," << endl
        << "  options_ (options)," << endl
        << "  options_count_ (options_count)," << endl
        << "  i_ (1)";