extern statement

src/analyzer.rs

@@ -87,6 +87,7 @@ impl Analyzer {
             }
             Stmt::Break => {}
             Stmt::Continue => {}
+            Stmt::Extern(_) => {}
         }
         Ok(())
     }

src/codegen_x86_64.rs

@@ -281,6 +281,9 @@ _builtin_set64:
                 // TODO: skips incrementing when used in a for loop
                 emit!(&mut self.output, "    jmp {}", env.loop_begin_label);
             }
+            Stmt::Extern(name) => {
+                emit!(&mut self.output, "    extern {}", name.lexeme);
+            }
         }
         Ok(())
     }

src/parser.rs

@@ -39,6 +39,7 @@ pub enum Stmt {
     Return(Expr),
     Break,
     Continue,
+    Extern(Token),
 }
 
 #[derive(Debug, Clone)]
@@ -198,6 +199,10 @@ impl Parser {
             Ok(Stmt::Break)
         } else if self.match_token(&[TokenType::KeywordContinue]) {
             Ok(Stmt::Continue)
+        } else if self.match_token(&[TokenType::KeywordExtern]) {
+            Ok(Stmt::Extern(
+                self.consume(TokenType::Identifier, "expected extern name")?,
+            ))
         } else {
             Ok(Stmt::Expression(self.expression()?))
         }

src/tokenizer.rs

@@ -47,6 +47,7 @@ pub enum TokenType {
     KeywordReturn,
     KeywordBreak,
     KeywordContinue,
+    KeywordExtern,
 
     Indent,
     Dedent,
@@ -334,6 +335,7 @@ impl Tokenizer {
             "return" => TokenType::KeywordReturn,
             "break" => TokenType::KeywordBreak,
             "continue" => TokenType::KeywordContinue,
+            "extern" => TokenType::KeywordExtern,
             "true" => TokenType::True,
             "false" => TokenType::False,
             _ => TokenType::Identifier,