Unreachable statement

3 files changed, 17 insertions, 2 deletions

diff --git a/src/compiler.rs b/src/compiler.rs
index 4bd519d..94bc0cf 100644
--- a/src/compiler.rs
+++ b/src/compiler.rs
@@ -354,10 +354,11 @@ impl Compiler {
         self.scope(block);
 
         if Token::Else == self.peek() {
+            self.eat();
+
             let else_jmp = block.add(Op::Illegal, self.line());
             block.patch(Op::JmpFalse(block.curr()), jump);
 
-            self.eat();
             match self.peek() {
                 Token::If => self.if_statment(block),
                 Token::LeftBrace => self.scope(block),
@@ -407,6 +408,11 @@ impl Compiler {
                 self.if_statment(block);
             }
 
+            (Token::Unreachable, _, _, _) => {
+                self.eat();
+                block.add(Op::Unreachable, self.line());
+            }
+
             (Token::LeftBrace, _, _, _) => {
                 self.scope(block);
             }
diff --git a/src/error.rs b/src/error.rs
index d79a5fb..abf8810 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -8,6 +8,7 @@ pub enum ErrorKind {
     TypeError(Op, Vec<Value>),
     AssertFailed(Value, Value),
     InvalidProgram,
+    Unreachable,
 
     SyntaxError(usize, Token),
 }
@@ -35,6 +36,9 @@ impl fmt::Display for ErrorKind {
             ErrorKind::SyntaxError(line, token) => {
                 write!(f, "Syntax error on line {} at token {:?}", line, token)
             }
+            ErrorKind::Unreachable => {
+                write!(f, "Reached unreachable code.")
+            }
             ErrorKind::InvalidProgram => {
                 write!(f, "[!!!] Invalid program")
             }
diff --git a/src/vm.rs b/src/vm.rs
index 7f121d4..8bdd313 100644
--- a/src/vm.rs
+++ b/src/vm.rs
@@ -44,6 +44,7 @@ pub enum Op {
     Greater, // >
 
     AssertEqual,
+    Unreachable,
 
     ReadLocal(usize),
     Assign(usize),
@@ -148,7 +149,7 @@ impl VM {
     }
 
     pub fn run(&mut self) -> Result<(), Error>{
-        const PRINT_WHILE_RUNNING: bool = true;
+        const PRINT_WHILE_RUNNING: bool = false;
         const PRINT_BLOCK: bool = true;
 
         if PRINT_BLOCK {
@@ -176,6 +177,10 @@ impl VM {
                     error!(self, ErrorKind::InvalidProgram);
                 }
 
+                Op::Unreachable => {
+                    error!(self, ErrorKind::Unreachable);
+                }
+
                 Op::Pop => {
                     self.stack.pop();
                 }