Support for methods. Started support for functions defined in script but not yet ready

src/engine.rs

@@ -6,7 +6,6 @@ use std::fmt;
 
 use parser::{lex, parse, Expr, Stmt };
 use fn_register::FnRegister;
-//use ops::{add_boxes, sub_boxes, mult_boxes, div_boxes};
 
 use std::ops::{Add, Sub, Mul, Div};
 use std::cmp::{Ord, Eq};
@@ -91,6 +90,7 @@ fn or(x: bool, y: bool) -> bool {
 }
 
 pub struct Engine {
+    pub fns_arity_3: HashMap<String, Vec<Box<Fn(&mut Box<Any>, &mut Box<Any>, &mut Box<Any>)->Result<Box<Any>, EvalError>>>>,
     pub fns_arity_2: HashMap<String, Vec<Box<Fn(&mut Box<Any>, &mut Box<Any>)->Result<Box<Any>, EvalError>>>>,
     pub fns_arity_1: HashMap<String, Vec<Box<Fn(&mut Box<Any>)->Result<Box<Any>, EvalError>>>>,
     pub fns_arity_0: HashMap<String, Vec<Box<Fn()->Result<Box<Any>, EvalError>>>>,
@@ -98,8 +98,8 @@ pub struct Engine {
 }
 
 impl Engine {
-    pub fn call_fn_0_arg(&self, name: &str) -> Result<Box<Any>, EvalError> {
-        match self.fns_arity_0.get(name) {
+    pub fn call_fn_0_arg(fns_arity_0: &HashMap<String, Vec<Box<Fn()->Result<Box<Any>, EvalError>>>>, name: &str) -> Result<Box<Any>, EvalError> {
+        match fns_arity_0.get(name) {
             Some(vf) => {
                 for f in vf {
                     let invoke = f();
@@ -114,8 +114,10 @@ impl Engine {
         }
     }
 
-    pub fn call_fn_1_arg(&self, name: &str, arg1: &mut Box<Any>) -> Result<Box<Any>, EvalError> {
-        match self.fns_arity_1.get(name) {
+    pub fn call_fn_1_arg(fns_arity_1: &HashMap<String, Vec<Box<Fn(&mut Box<Any>)->Result<Box<Any>, EvalError>>>>, 
+        name: &str, arg1: &mut Box<Any>) -> Result<Box<Any>, EvalError> {
+        
+        match fns_arity_1.get(name) {
             Some(vf) => {
                 for f in vf {
                     let invoke = f(arg1);
@@ -130,8 +132,10 @@ impl Engine {
         }
     }
 
-    pub fn call_fn_2_arg(&self, name: &str, arg1: &mut Box<Any>, arg2: &mut Box<Any>) -> Result<Box<Any>, EvalError> {
-        match self.fns_arity_2.get(name) {
+    pub fn call_fn_2_arg(fns_arity_2: &HashMap<String, Vec<Box<Fn(&mut Box<Any>, &mut Box<Any>)->Result<Box<Any>, EvalError>>>>, 
+        name: &str, arg1: &mut Box<Any>, arg2: &mut Box<Any>) -> Result<Box<Any>, EvalError> {
+        
+        match fns_arity_2.get(name) {
             Some(vf) => {
                 for f in vf {
                     let invoke = f(arg1, arg2);
@@ -146,6 +150,24 @@ impl Engine {
         }
     }
 
+    pub fn call_fn_3_arg(fns_arity_3: &HashMap<String, Vec<Box<Fn(&mut Box<Any>, &mut Box<Any>, &mut Box<Any>)->Result<Box<Any>, EvalError>>>>, 
+        name: &str, arg1: &mut Box<Any>, arg2: &mut Box<Any>, arg3: &mut Box<Any>) -> Result<Box<Any>, EvalError> {
+        
+        match fns_arity_3.get(name) {
+            Some(vf) => {
+                for f in vf {
+                    let invoke = f(arg1, arg2, arg3);
+                    match invoke {
+                        Ok(v) => return Ok(v),
+                        _ => ()
+                    }
+                };
+                Err(EvalError::FunctionArgMismatch)
+            }
+            None => Err(EvalError::FunctionNotFound)
+        }
+    }
+
     fn register_type<T: Clone+Any>(&mut self) {
         fn clone_helper<T: Clone>(t:T)->T { t.clone() };
 
@@ -196,20 +218,61 @@ impl Engine {
                     _ => Err(EvalError::VariableNotFound)
                 }
             }
-            Expr::Call(ref fn_name, ref args) => {
+            Expr::FnCall(ref fn_name, ref args) => {
                 if args.len() == 0 {
-                    self.call_fn_0_arg(&fn_name)
+                    Engine::call_fn_0_arg(&self.fns_arity_0, &fn_name)
                 }
                 else if args.len() == 1 {
                     let mut arg = try!(self.eval_expr(&args[0]));
 
-                    self.call_fn_1_arg(&fn_name, &mut arg)
+                    Engine::call_fn_1_arg(&self.fns_arity_1, &fn_name, &mut arg)
                 }
                 else if args.len() == 2 {
                     let mut arg1 = try!(self.eval_expr(&args[0]));
                     let mut arg2 = try!(self.eval_expr(&args[1]));
 
-                    self.call_fn_2_arg(&fn_name, &mut arg1, &mut arg2)
+                    Engine::call_fn_2_arg(&self.fns_arity_2, &fn_name, &mut arg1, &mut arg2)
+                }
+                else if args.len() == 3 {
+                    let mut arg1 = try!(self.eval_expr(&args[0]));
+                    let mut arg2 = try!(self.eval_expr(&args[1]));
+                    let mut arg3 = try!(self.eval_expr(&args[1]));
+
+                    Engine::call_fn_3_arg(&self.fns_arity_3, &fn_name, &mut arg1, &mut arg2, &mut arg3)
+                }
+                else {
+                    Err(EvalError::FunctionCallNotSupported)
+                }
+            }
+            Expr::MethodCall(ref target, ref fn_name, ref args) => {
+                if args.len() == 0 {
+                    for &mut (ref name, ref mut val) in &mut self.scope.iter_mut().rev() {
+                        if *target == *name {
+                            return Engine::call_fn_1_arg(&self.fns_arity_1, &fn_name, val);
+                        }
+                    }
+                    Err(EvalError::VariableNotFound)
+                }
+                else if args.len() == 1 {
+                    let mut arg = try!(self.eval_expr(&args[0]));
+
+                    for &mut (ref name, ref mut val) in &mut self.scope.iter_mut().rev() {
+                        if *target == *name {
+                            return Engine::call_fn_2_arg(&self.fns_arity_2, &fn_name, val, &mut arg);
+                        }
+                    }
+                    Err(EvalError::VariableNotFound)
+                }
+                else if args.len() == 2 {
+                    let mut arg1 = try!(self.eval_expr(&args[0]));
+                    let mut arg2 = try!(self.eval_expr(&args[1]));
+
+                    for &mut (ref name, ref mut val) in &mut self.scope.iter_mut().rev() {
+                        if *target == *name {
+                            return Engine::call_fn_3_arg(&self.fns_arity_3, &fn_name, val, &mut arg1, &mut arg2);
+                        }
+                    }
+                    Err(EvalError::VariableNotFound)
                 }
                 else {
                     Err(EvalError::FunctionCallNotSupported)
@@ -295,8 +358,19 @@ impl Engine {
         let tree = parse(&mut peekables);
 
         match tree {
-            Ok(os) => {
+            Ok((ref os, ref fns)) => {
                 let mut x: Result<Box<Any>, EvalError> = Ok(Box::new(()));
+                for f in fns {
+                    if f.params.len() == 0 {
+                        let local_f = f.clone();
+                        let ent = self.fns_arity_0.entry(local_f.name).or_insert(Vec::new());
+                        let wrapped : Box<Fn()->Result<Box<Any>, EvalError>> = 
+                            Box::new(move || { Ok(Box::new(0)) } );
+                        //move || { self.eval_stmt(&local_f.body) } 
+                        (*ent).push(wrapped);
+                    }
+                }
+
                 for o in os {
                     x = self.eval_stmt(&o)
                 }
@@ -342,8 +416,8 @@ impl Engine {
         reg_cmp!(engine, "<=", lte, i32, i64, u32, u64);
         reg_cmp!(engine, ">", gt, i32, i64, u32, u64);
         reg_cmp!(engine, ">=", gte, i32, i64, u32, u64);
-        reg_cmp!(engine, "==", eq, i32, i64, u32, u64);
-        reg_cmp!(engine, "!=", ne, i32, i64, u32, u64);
+        reg_cmp!(engine, "==", eq, i32, i64, u32, u64, bool);
+        reg_cmp!(engine, "!=", ne, i32, i64, u32, u64, bool);
 
         reg_op!(engine, "||", or, bool);
         reg_op!(engine, "&&", and, bool);
@@ -354,6 +428,7 @@ impl Engine {
             fns_arity_0: HashMap::new(), 
             fns_arity_1: HashMap::new(), 
             fns_arity_2: HashMap::new(), 
+            fns_arity_3: HashMap::new(), 
             scope: Vec::new() 
         };
 
@@ -463,4 +538,35 @@ fn test_var_scope() {
     }
 }
 
+#[test]
+fn test_method_call() {
+    #[derive(Debug, Clone)]
+    struct TestStruct {
+        x: i32
+    }
 
+    impl TestStruct {
+        fn update(&mut self) {
+            self.x += 1000;
+        }
+
+        fn new() -> TestStruct {
+            TestStruct { x: 1 }
+        }
+    }
+
+    let mut engine = Engine::new();
+
+    engine.register_type::<TestStruct>();
+
+    &(TestStruct::update as fn(&mut TestStruct)->()).register(&mut engine, "update");
+    &(TestStruct::new as fn()->TestStruct).register(&mut engine, "new_ts");
+
+    if let Ok(result) = engine.eval("var x = new_ts(); x.update(); x".to_string()).unwrap().downcast::<TestStruct>() {
+        assert_eq!(result.x, 1001);
+    }
+    else {
+        assert!(false);
+    }
+
+}

src/fn_register.rs

@@ -7,6 +7,48 @@ pub trait FnRegister {
     fn register(self, engine: &mut Engine, name: &str);
 }
 
+impl<T: Any+Clone, U: Any+Clone, V: Any+Clone, W: Any+Clone> FnRegister for fn(&mut T, U, V)->W {
+    fn register(self, engine: &mut Engine, name: &str) {
+        let wrapped : Box<Fn(&mut Box<Any>, &mut Box<Any>, &mut Box<Any>)->Result<Box<Any>, EvalError>> = 
+            Box::new(
+                move |x: &mut Box<Any>, y: &mut Box<Any>, z: &mut Box<Any>| {
+                    let inside1 = (*x).downcast_mut() as Option<&mut T>;
+                    let inside2 = (*y).downcast_mut() as Option<&mut U>;
+                    let inside3 = (*z).downcast_mut() as Option<&mut V>;
+                    
+                    match (inside1, inside2, inside3) {
+                        (Some(b), Some(c), Some(d)) => Ok(Box::new(self(b, c.clone(), d.clone())) as Box<Any>),
+                        _ => Err(EvalError::FunctionArgMismatch)
+                    }
+                }
+            );
+
+        let ent = engine.fns_arity_3.entry(name.to_string()).or_insert(Vec::new());
+        (*ent).push(wrapped);
+    }
+}
+
+impl<T: Any+Clone, U: Any+Clone, V: Any+Clone, W: Any+Clone> FnRegister for fn(T, U, V)->W {
+    fn register(self, engine: &mut Engine, name: &str) {
+        let wrapped : Box<Fn(&mut Box<Any>, &mut Box<Any>, &mut Box<Any>)->Result<Box<Any>, EvalError>> = 
+            Box::new(
+                move |x: &mut Box<Any>, y: &mut Box<Any>, z: &mut Box<Any>| {
+                    let inside1 = (*x).downcast_mut() as Option<&mut T>;
+                    let inside2 = (*y).downcast_mut() as Option<&mut U>;
+                    let inside3 = (*z).downcast_mut() as Option<&mut V>;
+                    
+                    match (inside1, inside2, inside3) {
+                        (Some(b), Some(c), Some(d)) => Ok(Box::new(self(b.clone(), c.clone(), d.clone())) as Box<Any>),
+                        _ => Err(EvalError::FunctionArgMismatch)
+                    }
+                }
+            );
+
+        let ent = engine.fns_arity_3.entry(name.to_string()).or_insert(Vec::new());
+        (*ent).push(wrapped);
+    }
+}
+
 impl<T: Any+Clone, U: Any+Clone, V: Any+Clone> FnRegister for fn(&mut T, U)->V {
     fn register(self, engine: &mut Engine, name: &str) {
         let wrapped : Box<Fn(&mut Box<Any>, &mut Box<Any>)->Result<Box<Any>, EvalError>> = 

src/main.rs

@@ -14,78 +14,9 @@ mod parser;
 // Todo (in no particular order):
 // * Function in script
 // * Doc some examples
-// * Refactor identifer to not require inlining of clone lookup in engine
+// * String constants
 // * Remove empty box values?
-// * Methods
-
-/*
-fn simple_fn(x: i32) -> bool { x == 1 }
-fn simple_fn2(x: &mut i32) -> bool { x.clone() == 2 }
-
-#[derive(Debug)]
-struct TestStruct {
-    x: i32
-}
-
-impl TestStruct {
-    fn update(&mut self) {
-        self.x += 1000;
-    }
-
-    fn new() -> TestStruct {
-        TestStruct { x: 1 }
-    }
-}
-
-#[derive(Debug)]
-struct TestStruct2 {
-    x: bool
-}
-
-impl TestStruct2 {
-    fn update(&mut self) {
-        self.x = true;
-    }
-}
-
-fn engine_test() {
-    let mut engine = Engine::new();
-
-    &(simple_fn as fn(i32)->bool).register(&mut engine, "simple_fn"); 
-    &(simple_fn2 as fn(&mut i32)->bool).register(&mut engine, "simple_fn2");
-    &(TestStruct::update as fn(&mut TestStruct)->()).register(&mut engine, "update");
-    &(TestStruct::new as fn()->TestStruct).register(&mut engine, "newteststruct");
-    &(showit as fn(x: &mut Box<Debug>)->()).register(&mut engine, "showit");
-    &(TestStruct2::update as fn(&mut TestStruct2)->()).register(&mut engine, "update");
-
-    let mut arg : Box<Any> = Box::new(2);
-
-    println!("Result: {:?}", engine.call_fn_1_arg("simple_fn" , &mut arg).unwrap().downcast::<bool>());
-    println!("Result: {:?}", engine.call_fn_1_arg("simple_fn2", &mut arg).unwrap().downcast::<bool>());
-    println!("Intentional errors: ");
-    println!("  Result: {:?}", engine.call_fn_1_arg("simple_fn3", &mut arg));
-    arg = Box::new("foo");    
-    println!("  Result: {:?}", engine.call_fn_1_arg("simple_fn", &mut arg));
-
-    let mut ts : Box<Any> = Box::new(TestStruct { x: 6 });
-    engine.call_fn_1_arg("update" , &mut ts);
-    
-    let result : Result<Box<TestStruct>, Box<Any>> = ts.downcast();
-    println!("TS: {:?}", result);
-
-    let myts = engine.call_fn_0_arg("newteststruct").unwrap().downcast::<TestStruct>();
-    println!("MyTS: {:?}", myts);
-
-    let mut mybox = Box::new(Box::new(56) as Box<Debug>) as Box<Any>;
-    engine.call_fn_1_arg("showit", &mut mybox);
-
-    let mut ts2 : Box<Any> = Box::new(TestStruct2 { x: false });
-    engine.call_fn_1_arg("update" , &mut ts2);
-
-    let result2 : Result<Box<TestStruct2>, Box<Any>> = ts2.downcast();
-    println!("TS2: {:?}", result2);
-}
-*/
+// * Refactor identifer to not require inlining of clone lookup in engine?
 
 fn showit<T: Display>(x: &mut T) -> () {
     println!("{}", x)

src/parser.rs

@@ -13,7 +13,10 @@ pub enum ParseError {
     MissingLCurly,
     MissingRCurly,
     MalformedCallExpr,
-    VarExpectsIdentifier
+    VarExpectsIdentifier,
+    ExpectedMethodInvocation,
+    FnMissingName,
+    FnMissingParams
 }
 
 impl Error for ParseError {
@@ -26,7 +29,10 @@ impl Error for ParseError {
             ParseError::MissingLCurly => "Expected '{'",
             ParseError::MissingRCurly => "Expected '}'",
             ParseError::MalformedCallExpr => "Call contains bad expression",
-            ParseError::VarExpectsIdentifier => "'var' expects the name of a variable"
+            ParseError::VarExpectsIdentifier => "'var' expects the name of a variable",
+            ParseError::ExpectedMethodInvocation => "Expected method call after '.'",
+            ParseError::FnMissingName => "Function declaration is missing name",
+            ParseError::FnMissingParams => "Function declaration is missing parameters"
         }
     }
 
@@ -41,17 +47,25 @@ impl fmt::Display for ParseError {
     }
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
+pub struct FnDef {
+    pub name: String,
+    pub params: Vec<String>,
+    pub body: Box<Stmt>
+}
+
+#[derive(Debug, Clone)]
 pub enum Stmt { If(Box<Expr>, Box<Stmt>), While(Box<Expr>, Box<Stmt>), Var(String, Option<Box<Expr>>),
     Block(Box<Vec<Stmt>>), Expr(Box<Expr>) }
 
-#[derive(Debug)]
-pub enum Expr { IntConst(i32), Identifier(String), Call(String, Box<Vec<Expr>>), Assignment(Box<Expr>, Box<Expr>), True, False }
+#[derive(Debug, Clone)]
+pub enum Expr { IntConst(i32), Identifier(String), FnCall(String, Box<Vec<Expr>>), MethodCall(String, String, Box<Vec<Expr>>), 
+    Assignment(Box<Expr>, Box<Expr>), True, False }
 
 #[derive(Debug)]
 pub enum Token { Int(i32), Id(String), LCurly, RCurly, LParen, RParen, LSquare, RSquare,
-    Plus, Minus, Multiply, Divide, Semicolon, Colon, Comma, Equals, True, False, Var, If, While,
-    LessThan, GreaterThan, Bang, LessThanEqual, GreaterThanEqual, EqualTo, NotEqualTo, Pipe, Or, Ampersand, And }
+    Plus, Minus, Multiply, Divide, Semicolon, Colon, Comma, Period, Equals, True, False, Var, If, While,
+    LessThan, GreaterThan, Bang, LessThanEqual, GreaterThanEqual, EqualTo, NotEqualTo, Pipe, Or, Ampersand, And, Fn }
 
 pub struct TokenIterator<'a> {
     char_stream: Peekable<Chars<'a>>
@@ -110,6 +124,9 @@ impl<'a> Iterator for TokenIterator<'a> {
                     else if out == "while" {
                         return Some(Token::While);
                     }
+                    else if out == "fn" {
+                        return Some(Token::Fn);
+                    }
                     else {
                         return Some(Token::Id(out));
                     }
@@ -127,6 +144,7 @@ impl<'a> Iterator for TokenIterator<'a> {
                 ';' => { return Some(Token::Semicolon); },
                 ':' => { return Some(Token::Colon); },
                 ',' => { return Some(Token::Comma); },
+                '.' => { return Some(Token::Period); },
                 '=' => { 
                     match self.char_stream.peek() {
                         Some(&'=') => {self.char_stream.next(); return Some(Token::EqualTo); },
@@ -204,17 +222,35 @@ fn parse_paren_expr<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Expr,
 }
 
 fn parse_ident_expr<'a>(id: String, input: &mut Peekable<TokenIterator<'a>>) -> Result<Expr, ParseError> {    
+    let id2 = match input.peek() {
+        Some(&Token::Period) => {
+            input.next();
+            match input.next() {
+                Some(Token::Id(ref s)) => {
+                    s.clone()
+                }
+                _ => return Err(ParseError::ExpectedMethodInvocation)
+            }
+        },
+        _ => String::new()
+    };
     match input.peek() {
-        Some(&Token::LParen) => (),
+        Some(&Token::LParen) => {input.next();},
         _ => return Ok(Expr::Identifier(id))
     }
 
-    input.next();
-
     let mut args = Vec::new();
 
     match input.peek() {
-        Some(&Token::RParen) => {input.next(); return Ok(Expr::Call(id, Box::new(args)))},
+        Some(&Token::RParen) => {
+            input.next(); 
+            if id2 == "" {
+                return Ok(Expr::FnCall(id, Box::new(args)))
+            }
+            else {
+                return Ok(Expr::MethodCall(id, id2, Box::new(args)))
+            }
+        },
         _ => ()
     }
 
@@ -227,7 +263,15 @@ fn parse_ident_expr<'a>(id: String, input: &mut Peekable<TokenIterator<'a>>) ->
         }
 
         match input.peek() {
-            Some(&Token::RParen) => {input.next(); return Ok(Expr::Call(id, Box::new(args)))},
+            Some(&Token::RParen) => {
+                input.next();
+                if id2 == "" {
+                    return Ok(Expr::FnCall(id, Box::new(args)))
+                }
+                else {
+                    return Ok(Expr::MethodCall(id, id2, Box::new(args)))
+                }
+            },
             Some(&Token::Comma) => (),
             _ => return Err(ParseError::MalformedCallExpr)
         }
@@ -280,19 +324,19 @@ fn parse_binop<'a>(input: &mut Peekable<TokenIterator<'a>>, prec: i32, lhs: Expr
             }
 
             lhs_curr = match op_token {
-                Token::Plus => Expr::Call("+".to_string(), Box::new(vec![lhs_curr, rhs])),
-                Token::Minus => Expr::Call("-".to_string(), Box::new(vec![lhs_curr, rhs])),
-                Token::Multiply => Expr::Call("*".to_string(), Box::new(vec![lhs_curr, rhs])),
-                Token::Divide => Expr::Call("/".to_string(), Box::new(vec![lhs_curr, rhs])),
+                Token::Plus => Expr::FnCall("+".to_string(), Box::new(vec![lhs_curr, rhs])),
+                Token::Minus => Expr::FnCall("-".to_string(), Box::new(vec![lhs_curr, rhs])),
+                Token::Multiply => Expr::FnCall("*".to_string(), Box::new(vec![lhs_curr, rhs])),
+                Token::Divide => Expr::FnCall("/".to_string(), Box::new(vec![lhs_curr, rhs])),
                 Token::Equals => Expr::Assignment(Box::new(lhs_curr), Box::new(rhs)),
-                Token::EqualTo => Expr::Call("==".to_string(), Box::new(vec![lhs_curr, rhs])),
-                Token::NotEqualTo => Expr::Call("!=".to_string(), Box::new(vec![lhs_curr, rhs])),
-                Token::LessThan => Expr::Call("<".to_string(), Box::new(vec![lhs_curr, rhs])),
-                Token::LessThanEqual => Expr::Call("<=".to_string(), Box::new(vec![lhs_curr, rhs])),
-                Token::GreaterThan => Expr::Call(">".to_string(), Box::new(vec![lhs_curr, rhs])),
-                Token::GreaterThanEqual => Expr::Call(">=".to_string(), Box::new(vec![lhs_curr, rhs])),
-                Token::Or => Expr::Call("||".to_string(), Box::new(vec![lhs_curr, rhs])),
-                Token::And => Expr::Call("&&".to_string(), Box::new(vec![lhs_curr, rhs])),
+                Token::EqualTo => Expr::FnCall("==".to_string(), Box::new(vec![lhs_curr, rhs])),
+                Token::NotEqualTo => Expr::FnCall("!=".to_string(), Box::new(vec![lhs_curr, rhs])),
+                Token::LessThan => Expr::FnCall("<".to_string(), Box::new(vec![lhs_curr, rhs])),
+                Token::LessThanEqual => Expr::FnCall("<=".to_string(), Box::new(vec![lhs_curr, rhs])),
+                Token::GreaterThan => Expr::FnCall(">".to_string(), Box::new(vec![lhs_curr, rhs])),
+                Token::GreaterThanEqual => Expr::FnCall(">=".to_string(), Box::new(vec![lhs_curr, rhs])),
+                Token::Or => Expr::FnCall("||".to_string(), Box::new(vec![lhs_curr, rhs])),
+                Token::And => Expr::FnCall("&&".to_string(), Box::new(vec![lhs_curr, rhs])),
                 _ => return Err(ParseError::UnknownOperator)
             };
         }
@@ -349,7 +393,27 @@ fn parse_block<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Stmt, Pars
 
     input.next();
 
-    let stmts = try!(parse_stmts(input, true));
+    let mut stmts = Vec::new();
+
+    let skip_body = match input.peek() {
+        Some(& Token::RCurly) => true,
+        _ => false
+    };
+
+    if !skip_body {
+        while let Some(_) = input.peek() {
+            stmts.push(try!(parse_stmt(input)));
+            match input.peek() {
+                Some(& Token::Semicolon) => {input.next();},            
+                _ => ()
+            }
+
+            match input.peek() {
+                Some(& Token::RCurly) => break,
+                _ => ()
+            }
+        }        
+    }
 
     match input.peek() {
         Some(& Token::RCurly) => {input.next(); Ok(Stmt::Block(Box::new(stmts)))},
@@ -372,35 +436,61 @@ fn parse_stmt<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Stmt, Parse
     }
 }
 
-fn parse_stmts<'a>(input: &mut Peekable<TokenIterator<'a>>, check_for_rcurly: bool) -> Result<Vec<Stmt>, ParseError> {
-    let mut result = Vec::new();
+fn parse_fn<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<FnDef, ParseError> {
+    input.next();
 
-    if check_for_rcurly {
-        match input.peek() {
-            Some(& Token::RCurly) => return Ok(result),
-            _ => ()
-        }        
+    let name = match input.next() {
+        Some(Token::Id(ref s)) => s.clone(),
+        _ => return Err(ParseError::FnMissingName)
+    };
+
+    match input.peek() {
+        Some(&Token::LParen) => {input.next();},
+        _ => return Err(ParseError::FnMissingParams)
     }
 
-    while let Some(_) = input.peek() {
-        result.push(try!(parse_stmt(input)));
-        match input.peek() {
-            Some(& Token::Semicolon) => {input.next();},            
-            _ => ()
-        }
+    let mut params = Vec::new();
 
-        if check_for_rcurly {
-            match input.peek() {
-                Some(& Token::RCurly) => return Ok(result),
-                _ => ()
+    let skip_params = match input.peek() {
+        Some(&Token::RParen) => { input.next(); true }
+        _ => false
+    };
+
+    if !skip_params {
+        loop {
+            match input.next() {
+                Some(Token::RParen) => { break },
+                Some(Token::Comma) => (),
+                Some(Token::Id(ref s)) => { params.push(s.clone()); },
+                _ => return Err(ParseError::MalformedCallExpr)
             }
         }        
     }
 
-    Ok(result)
+    let body = try!(parse_block(input));
+
+    Ok(FnDef{name: name, params: params, body: Box::new(body)})
 }
 
-pub fn parse<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Vec<Stmt>, ParseError> {
-    let result = parse_stmts(input, false);
-    result
+fn parse_top_level<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<(Vec<Stmt>, Vec<FnDef>), ParseError> {
+    let mut stmts = Vec::new();
+    let mut fndefs = Vec::new();
+
+    while let Some(_) = input.peek() {
+        match input.peek() {
+            Some(& Token::Fn) => fndefs.push(try!(parse_fn(input))),
+            _ => stmts.push(try!(parse_stmt(input)))
+        }
+
+        match input.peek() {
+            Some(& Token::Semicolon) => {input.next();},            
+            _ => ()
+        }
+    }
+
+    Ok((stmts, fndefs))
+}
+
+pub fn parse<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<(Vec<Stmt>, Vec<FnDef>), ParseError> {
+    parse_top_level(input)
 }