refactor(CLI): use arg_enum! clap-rs macro

That way, we get a better (case-insensitive) implementation of `FromStr`
which reduces the amount of code we have to maintain.

Closes #101
[skip ci]

src/mako/cli/lib/engine.mako

@@ -32,7 +32,7 @@
 %>\
 use cmn::{InvalidOptionsError, CLIError, JsonTokenStorage, arg_from_str, writer_from_opts, parse_kv_arg, 
           input_file_from_opts, input_mime_from_opts, FieldCursor, FieldError, CallType, UploadProtocol,
-          protocol_from_str};
+          calltype_from_str};
 
 use std::default::Default;
 use std::str::FromStr;
@@ -272,7 +272,7 @@ ${value_unwrap}\
 % endif # handle call parameters
 % if mc.media_params:
 let vals = opt.values_of("${MODE_ARG}").unwrap();
-let protocol = protocol_from_str(vals[0], [${', '.join('"%s"' % mp.protocol for mp in mc.media_params)}].iter().map(|&v| v.to_string()).collect(), err);
+let protocol = calltype_from_str(vals[0], [${', '.join('"%s"' % mp.protocol for mp in mc.media_params)}].iter().map(|&v| v.to_string()).collect(), err);
 let mut input_file = input_file_from_opts(vals[1], err);
 let mime_type = input_mime_from_opts(${opt_value(MIME_ARG, default=DEFAULT_MIME)}, err);
 % else:

src/mako/cli/main.rs.mako

@@ -15,6 +15,7 @@
 #![feature(plugin, exit_status)]
 #![allow(unused_variables, unused_imports, dead_code, unused_mut)]
 
+#[macro_use]
 extern crate clap;
 extern crate yup_oauth2 as oauth2;
 extern crate yup_hyper_mock as mock;

src/rust/cli/cmn.rs

@@ -37,9 +37,11 @@ pub enum CallType {
     Standard,
 }
 
-pub enum UploadProtocol {
-    Simple,
-    Resumable,
+arg_enum!{
+    pub enum UploadProtocol {
+        Simple,
+        Resumable
+    }
 }
 
 impl AsRef<str> for UploadProtocol {
@@ -60,18 +62,6 @@ impl AsRef<str> for CallType {
     }
 }
 
-impl FromStr for UploadProtocol {
-    type Err = String;
-
-    fn from_str(s: &str) -> Result<UploadProtocol, String> {
-        match s {
-            "simple" => Ok(UploadProtocol::Simple),
-            "resumable" => Ok(UploadProtocol::Resumable),
-            _ => Err(format!("Protocol '{}' is unknown", s)),
-        }        
-    }
-}
-
 #[derive(Clone, Default)]
 pub struct FieldCursor(Vec<String>);
 
@@ -210,7 +200,7 @@ pub fn parse_kv_arg<'a>(kv: &'a str, err: &mut InvalidOptionsError, for_hashmap:
     }
 }
 
-pub fn protocol_from_str(name: &str, valid_protocols: Vec<String>, err: &mut InvalidOptionsError) -> CallType {
+pub fn calltype_from_str(name: &str, valid_protocols: Vec<String>, err: &mut InvalidOptionsError) -> CallType {
     CallType::Upload(
         match UploadProtocol::from_str(name) {
             Ok(up) => up,