read from file or stdin, add readme

src/main.rs

@@ -4,6 +4,10 @@ mod parser;
 mod context;
 mod vm;
 
+use std::{
+    env,
+    fs::read_to_string,
+};
 use err::*;
 use parser::*;
 use context::*;
@@ -13,16 +17,45 @@ use vm::*;
 // https://playsecurity.org/rawfile/grass_mud_horse_language_specification.md
 // https://p.rogram.me/grassmudhorse.js/grassmudhorse.js
 fn main() {
-    let input = "草草草泥马 马草草草泥草草草草泥泥马 草马草 泥马草泥 草草草泥草泥草马 泥马草草 草草草泥马 泥草草草 草马草 草草草泥草泥泥马 泥草草泥 马泥草草泥草草草泥草泥马 马草马草泥草草草草泥泥马 马草草草泥草草草泥草泥马 草马马 马马马";
+    let is_help = env::args().any(|a| a == "-h" || a == "--help");
+    if is_help {
+        println!("grassmudhorse.rs v0.1");
+        return;
+    }
+    let is_debug = env::args().any(|a| a == "-d" || a == "--debug");
 
-    let instructions = match parse_lang(input) {
+    let arg_file = env::args().filter(|a| !a.starts_with("-")).nth(1);
+
+    let input = match arg_file {
+        Some(f) => match read_to_string(&f) {
+            Ok(s) => s, Err(err) => {
+                println!("[ERROR] Read file {}, error: {}", f, err);
+                return;
+            }
+        },
+        None => {
+            let mut buff = String::new();
+            use std::io::Read;
+            match std::io::stdin().lock().read_to_string(&mut buff) {
+                Ok(_) => buff,
+                Err(err) => {
+                    println!("[ERROR] Read stdin, error: {}", err);
+                    return;
+                }
+            }
+        },
+    };
+    
+    
+
+    let instructions = match parse_lang(&input) {
         Ok(i) => i, Err(err) => {
             println!("Parse error: {}", err);
             return;
         },
     };
 
-    let mut context = Context::new(false);
+    let mut context = Context::new(is_debug);
 
     if context.is_debug() {
         println!("[DEBUG] parsed instructions:");