Add quick-and-dirty binary for loading and evaluating grammars

src/bin/purrchance.rs

@@ -0,0 +1,25 @@
+use purrchance::*;
+use purrchance::parser::*;
+
+use std::env;
+use std::fs::read_to_string;
+use std::process::exit;
+
+fn main() {
+    let args: Vec<String> = env::args().collect();
+
+    if args.len() < 2 {
+        eprintln!("too few arguments!");
+        exit(1);
+    }
+
+    let raw_grammar = read_to_string(&args[1]).unwrap();
+    let grammar = load_grammar(&raw_grammar);
+    if args.len() < 3 {
+        eprintln!("{:?}", grammar);
+        exit(0);
+    }
+
+    let sym = Symbol::NonTerminal(args[2].clone());
+    println!("{}", sym.eval(&grammar).unwrap());
+}