Change "imag" impl to not instantiate Runtime object

Adapt libimagrt interface to export the functions we need to do this.
This is not that nice, but the best approach without rewriting large
parts of libimagrt.

bin/core/imag/Cargo.toml

@@ -26,6 +26,7 @@ walkdir = "1"
 log = "0.4.0"
 toml = "0.4"
 toml-query = "0.6"
+is-match = "0.1"
 
 libimagrt    = { version = "0.7.0", path = "../../../lib/core/libimagrt" }
 libimagerror = { version = "0.7.0", path = "../../../lib/core/libimagerror" }

bin/core/imag/src/main.rs

@@ -22,6 +22,7 @@ extern crate clap;
 extern crate walkdir;
 extern crate toml;
 extern crate toml_query;
+#[macro_use] extern crate is_match;
 
 #[macro_use] extern crate libimagrt;
 extern crate libimagerror;
@@ -33,16 +34,19 @@ use std::process::Stdio;
 use std::io::ErrorKind;
 use std::io::{stdout, Stdout, Write};
 use std::collections::BTreeMap;
+use std::path::PathBuf;
 
 use walkdir::WalkDir;
 use clap::{Arg, ArgMatches, AppSettings, SubCommand};
 use toml::Value;
 use toml_query::read::TomlValueReadExt;
 
+use libimagrt::error::RuntimeErrorKind;
 use libimagrt::runtime::Runtime;
-use libimagerror::trace::trace_error;
+use libimagrt::spec::CliSpec;
 use libimagerror::io::ToExitCode;
 use libimagerror::exit::ExitUnwrap;
+use libimagerror::trace::trace_error;
 
 /// Returns the helptext, putting the Strings in cmds as possible
 /// subcommands into it
@@ -165,15 +169,23 @@ fn main() {
         }
     }
 
-    let rt = Runtime::new(app)
-        .unwrap_or_else(|e| {
-            let _ = writeln!(out, "Runtime couldn't be setup. Exiting")
-                .to_exit_code()
-                .unwrap_or_exit();
-            trace_error(&e);
-            exit(1);
-        });
-    let matches = rt.cli();
+    let matches = app.matches();
+    let rtp = ::libimagrt::runtime::get_rtp_match(&matches);
+    let configpath = matches
+        .value_of(Runtime::arg_config_name())
+        .map_or_else(|| rtp.clone(), PathBuf::from);
+    debug!("Config path = {:?}", configpath);
+    let config = match ::libimagrt::configuration::fetch_config(&configpath) {
+            Ok(c) => Some(c),
+            Err(e) => if !is_match!(e.kind(), &RuntimeErrorKind::ConfigNoConfigFileFound) {
+                trace_error(&e);
+                ::std::process::exit(1)
+            } else {
+                println!("No config file found.");
+                println!("Continuing without configuration file");
+                None
+            },
+    };
 
     debug!("matches: {:?}", matches);
 
@@ -214,7 +226,7 @@ fn main() {
         exit(0);
     }
 
-    let aliases = match fetch_aliases(&rt) {
+    let aliases = match fetch_aliases(config.as_ref()) {
         Ok(aliases) => aliases,
         Err(e)      => {
             let _ = writeln!(out, "Error while fetching aliases from configuration file")
@@ -298,8 +310,8 @@ fn main() {
     }
 }
 
-fn fetch_aliases(rt: &Runtime) -> Result<BTreeMap<String, String>, String> {
-    let cfg   = rt.config().ok_or_else(|| String::from("No configuration found"))?;
+fn fetch_aliases(config: Option<&Value>) -> Result<BTreeMap<String, String>, String> {
+    let cfg   = config.ok_or_else(|| String::from("No configuration found"))?;
     let value = cfg
         .read("imag.aliases")
         .map_err(|_| String::from("Reading from config failed"));

lib/core/libimagrt/src/runtime.rs

@@ -440,7 +440,8 @@ impl<'a> Runtime<'a> {
     }
 }
 
-fn get_rtp_match<'a>(matches: &ArgMatches<'a>) -> PathBuf {
+/// Exported for the `imag` command, you probably do not want to use that.
+pub fn get_rtp_match<'a>(matches: &ArgMatches<'a>) -> PathBuf {
     use std::env;
 
     matches.value_of(Runtime::arg_runtimepath_name())