Add assembler and execution logic

Most everything works, but there's one small bug with the execution
involving jumps - still have to figure that one out.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

src/main.rs

@@ -21,14 +21,29 @@ fn get_input_string() -> io::Result<String> {
 }
 
 fn main() -> Result<()> {
-    use vm::obj::syn::{lexer, parser};
+    use vm::{
+        state::State,
+        obj::{
+            assemble::{Asm, Assemble},
+            syn::{lexer, parser},
+        }
+    };
     let text = get_input_string()?;
     let lexerdef = lexer::lexerdef();
     let lexer = lexerdef.lexer(&text);
     let (res, errors) = parser::parse(&lexer);
-    for err in errors {
+    for err in errors.iter() {
         println!("{}", err.pp(&lexer, &parser::token_epp));
     }
-    println!("{:?}", res);
+    if !errors.is_empty() {
+        return Ok(());
+    }
+    let res = res.unwrap();
+    let mut asm = Asm::default();
+    let object = res.assemble(&mut asm)?;
+    let mut state = State::new();
+    state.load_object(object, 64 * 1024 * 1024)?;
+    let status = state.exec()?;
+    println!("exit status: {}", status);
     Ok(())
 }