Use WithCoord parameter parsing for argv

This moves the parameter parsing for the `+<line>:<column>` switch
of the commandline to the `ParametersParser`. The position switch now
respects the `--` separator between switches and files.

The manpage does not document the old behaviour of `+:[column]`.
`+:[column]` works exactly like `+`. This is compatible with the
previously documented behaviour for `+:`.

The help message is does not mention that omitting the line or column
moves the cursor to the last line or column. The explanation in the
manpage should suffice.

doc/kak.1

@@ -14,7 +14,8 @@
 .Op Fl ui Ar ui_type
 .Op Fl e Ar command
 .Op Fl E Ar command
-.Op Sy + Ns Ar line Ns Oo Sy \&: Ns Ar column Oc | Sy +:
+.Op Sy + Ns Oo Ns Ar line Oc | Sy + Ns Ar line Ns Sy \&: Ns Oo Ns Ar column Oc
+.Op Fl Fl
 .Op Ar file ...
 .
 .Nm
@@ -151,10 +152,10 @@ Begin in
 .Em readonly mode ,
 all the buffers opened will not be written to disk.
 .
-.It Sy + Ns Ar line Ns Oo Sy \&: Ns Ar column Oc | Sy +:
+.It Sy + Ns Oo Ns Ar line Oc | Sy + Ns Ar line Ns Sy \&: Ns Oo Ns Ar column Oc
 Specify a target line and column for the first file.
-When the plus sign is followed by only a colon, then the cursor is sent
-to the last line of the file.
+When the line is omitted the cursor will go to the end of the buffer.
+When colon is present but the column is omitted the cursor will got to the end of the given line.
 .
 .It Ar file ...
 One or more

src/main.cc

@@ -1102,18 +1102,17 @@ int main(int argc, char* argv[])
                    { "debug", { ArgCompleter{}, "initial debug option value" } },
                    { "version", { {}, "display kakoune version and exit" } },
                    { "ro", { {}, "readonly mode" } },
-                   { "help", { {}, "display a help message and quit" } } }
+                   { "help", { {}, "display a help message and quit" } } },
+        ParameterDesc::Flags::WithCoord
     };
 
     try
     {
         auto show_usage = [&]() {
-            write_stdout(format("Usage: {} [options] [--] [file]... [+<line>[:<col>]|+:]\n\n"
+            write_stdout(format("Usage: {} [options] [+[line] | +line:[column]] [--] [file]...\n\n"
                     "Options:\n"
                     "{}\n"
-                    "Prefixing a positional argument with a plus (`+`) sign will place the\n"
-                    "cursor at a given set of coordinates, or the end of the buffer if the plus\n"
-                    "sign is followed only by a colon (`:`)\n",
+                    "You can specify the initial position of the cursor using +[line] or +line:[column].\n",
                     argv[0], generate_switches_doc(param_desc.switches)));
             return 0;
         };
@@ -1182,32 +1181,8 @@ int main(int argc, char* argv[])
                               parser.get_switch("i").value_or(StringView{}));
         }
 
-        Vector<StringView> files;
-        Optional<BufferCoord> init_coord;
-        for (auto& name : parser)
-        {
-            if (not name.empty() and name[0_byte] == '+')
-            {
-                if (name == "+" or name  == "+:")
-                {
-                    client_init = client_init + "; exec gj";
-                    continue;
-                }
-                auto colon = find(name, ':');
-                if (auto line = str_to_int_ifp({name.begin()+1, colon}))
-                {
-                    init_coord = std::max<BufferCoord>({0,0}, {
-                        *line - 1,
-                        colon != name.end() ?
-                            str_to_int_ifp({colon+1, name.end()}).value_or(1) - 1
-                          : 0
-                    });
-                    continue;
-                }
-            }
-
-            files.emplace_back(name);
-        }
+        auto init_coord = parser.get_coord();
+        auto files = parser | gather<Vector<StringView>>();
 
         if (auto server_session = parser.get_switch("c"))
         {
@@ -1219,14 +1194,11 @@ int main(int argc, char* argv[])
                     return -1;
                 }
             }
+
             String new_files;
-            for (auto name : files) {
-                new_files += format("edit '{}'", escape(real_path(name), "'", '\''));
-                if (init_coord) {
-                    new_files += format(" {} {}", init_coord->line + 1, init_coord->column + 1);
-                    init_coord.reset();
-                }
-                new_files += ";";
+            for (auto file : files)
+            {
+                new_files += format("edit -- '{}'\n", escape(real_path(file), "'", '\''));
             }
 
             return run_client(*server_session, {}, new_files + client_init, init_coord, ui_type, false);