fix(clap): generate command data structure

We do this in the hopes to circumvent a stack overflow.
This means we will setup the parser entirely at runtime, which actually
saves a little bit of code.

src/mako/cli/lib/argparse.mako

@@ -7,6 +7,15 @@
 
     def rust_boolean(v):
         return v and 'true' or 'false'
+
+    def rust_optional(v):
+        if v is None:
+            return 'None'
+        if isinstance(v, bool):
+            v = v and 'true' or 'false'
+        elif isinstance(v, basestring):
+            v = '"%s"' % v
+        return 'Some(%s)' % v
 %>\
 <%def name="grammar(c)">\
 % for resource in sorted(c.rta_map.keys()):
@@ -109,7 +118,7 @@ Configuration:
         None
     ))
 %>\
-App::new("${util.program_name()}")
+let mut app = App::new("${util.program_name()}")
 <%block filter="indent_by(7)">\
 .author("${', '.join(cargo.authors)}")
 .version("${cargo.build_version}")
@@ -121,11 +130,17 @@ App::new("${util.program_name()}")
 .arg(Arg::with_name("${arg_name or flag}")
         .long("${flag}")
         .help("${desc}")
-        .takes_value(${rust_boolean(arg_name)}))
+        .takes_value(${rust_boolean(arg_name)}))\
+% if loop.last:
+;
+% else:
+
+% endif
 % endfor
+let arg_data = [
 % for resource in sorted(c.rta_map.keys()):
-.subcommand(
-    SubCommand::new("${mangle_subcommand(resource)}")
+<%block filter="indent_by(4)">\
+("${mangle_subcommand(resource)}", vec![
     % for method in sorted(c.rta_map[resource]):
 <%
     mc = new_method_context(resource, method, c)
@@ -193,30 +208,23 @@ App::new("${util.program_name()}")
             ))
     # handle output
 %>\
-    .subcommand(
-        SubCommand::new("${mangle_subcommand(method)}")
-            % if mc.m.get('description') is not None:
-            .about("${mc.m.description}")
-            % endif
+    ("${mangle_subcommand(method)}",  ${rust_optional(mc.m.get('description'))}, 
+          vec![
             % for flag, desc, arg_name, required, multi in args:
-            .arg(
-                Arg::with_name("${arg_name or flag}")
-                    % if flag:
-                        .short("${flag}")
-                    % endif
-                    % if desc:
-                        .help("${desc}")
-                    % endif
-                    % if flag is not None:
-                        .takes_value(${rust_boolean(arg_name)})
-                    % endif
-                        .required(${rust_boolean(required)})
-                        .multiple(${rust_boolean(multi)}))
+            (${rust_optional(arg_name)},
+             ${rust_optional(flag)},
+             ${rust_optional(desc)},
+             ${rust_optional(required)},
+             ${rust_optional(multi)}),
+            % if not loop.last:
+
+            % endif
             % endfor
-        )
+          ]),
     % endfor # each method
-    )
+    ]),
+</%block>
 % endfor # end for each resource
-.get_matches();
+];
 </%block>
 </%def>

src/mako/cli/lib/engine.mako

@@ -29,7 +29,7 @@
 %>\
 mod cmn;
 use cmn::{InvalidOptionsError, CLIError, JsonTokenStorage, arg_from_str, writer_from_opts, parse_kv_arg, 
-          input_file_from_opts, input_mime_from_opts, FieldCursor, FieldError};
+          input_file_from_opts, input_mime_from_opts, FieldCursor, FieldError, make_subcommand};
 
 use std::default::Default;
 use std::str::FromStr;

src/mako/cli/main.rs.mako

@@ -30,7 +30,6 @@ use clap::{App, SubCommand, Arg};
 ## ${engine.new(c)}\
 
 fn main() {
-    let matches = 
     ${argparse.new(c) | indent_all_but_first_by(1)}\
 
     ## let opts: Options = Options::docopt().decode().unwrap_or_else(|e| e.exit());

src/rust/cli/cmn.rs

@@ -1,6 +1,7 @@
 use oauth2::{ApplicationSecret, ConsoleApplicationSecret, TokenStorage, Token};
 use rustc_serialize::json;
 use mime::Mime;
+use clap::{App, SubCommand};
 
 use std::fs;
 use std::env;
@@ -15,6 +16,22 @@ use std::default::Default;
 
 const FIELD_SEP: char = '.';
 
+
+fn make_subcommand(command_name: &str, desc: Option<&str>,
+                                       args: &Vec<(Option<&str>, Option<&str>, Option<&str>, 
+                                                   Option<bool>, Option<bool>)>)
+                                                   -> App<'a, 'v, 'ab, 'u, 'h, 'ar> {
+   // arg_name: Option<&str>,
+   // short_name: Option<&str>,
+   // help: Option<&str>,
+   // % if flag is not None:
+   //                      .takes_value(${rust_boolean(arg_name)})
+   // required: Option<bool>,
+   // multiple: Option<bool>
+    SubCommand::new(command_name)
+}
+
+
 #[derive(Clone, Default)]
 pub struct FieldCursor(Vec<String>);