Detect arg parser to use

Switch Parser trait to an object safe trait so guess_parser can
return an boxed instance.

1 files changed, 17 insertions, 14 deletions

diff --git a/src/main.rs b/src/main.rs
index 347e144..4cfbcc7 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,8 +1,18 @@
 mod args;
 
-use crate::args::Parser;
 use std::process::ExitCode;
 
+fn guess_parser(args: &mut dyn Iterator<Item = String>) -> Box<dyn args::Parser> {
+    for arg in args {
+        if arg.len() > 2 && arg.starts_with("--") {
+            // --C.. can only be ShortAndLong
+            return Box::new(args::ShortAndLongParser::new());
+        }
+    }
+    // TODO: Can we make more guesses?
+    Box::new(args::LongOnlyParser::new())
+}
+
 fn parse_args() -> Result<bool, String> {
     let mut options = args::Options::new();
     let help_idx = options.push(
@@ -28,32 +38,25 @@ fn parse_args() -> Result<bool, String> {
             .build()
             .unwrap(),
     );
-    let test_idx = options.push(
-        args::OptionBuilder::default()
-            .short('t')
-            .long("test")
-            .description("testing")
-            .value(args::ValueRequirement::Required("FILE"))
-            .build()
-            .unwrap(),
-    );
 
-    let parser = args::ShortAndLongParser::new();
-    let args = parser.run(&mut options, std::env::args())?;
+    let parser = guess_parser(&mut std::env::args());
+    let maybe_args = parser.run(&mut options, &mut std::env::args());
+
+    // help is special, check for it even if parser#run returned error.
     let ref help = options[help_idx];
     if help.is_set() {
         parser.print_help(&options);
         return Ok(true);
     }
+
+    let args = maybe_args?;
     let ref version = options[version_idx];
     if version.is_set() {
         println!("Version is 0.0.1");
         return Ok(true);
     }
     let ref verbose = options[verbose_idx];
-    let ref test = options[test_idx];
     println!("verbose: {}", verbose.is_set());
-    println!("test: {:?}", test.value());
     println!("args: {:?}", args.args);
     Ok(false)
 }