While loop

src/lexer.rs

@@ -15,9 +15,10 @@ pub enum Token {
     #[token("struct")]    Struct,
     #[token("fn")]        Function,
     #[token("for")]       For,
+    #[token("in")]        In,
+    #[token("while")]     While,
     #[token("if")]        If,
     #[token("else")]      Else,
-    #[token("in")]        In,
     #[token("let")]       Let,
     #[token("mut")]       Mut,
     #[token("interface")] Interface,

src/parse.rs

@@ -317,6 +317,20 @@ impl<'a> BranchBody<'a> {
                         next = Some(tail);
                     }
                 }
+                Token::While => {
+                    let test_expr = match Expr::build(lexer) {
+                        (Some(test_expr), Token::BraceOpen) => test_expr,
+                        (Some(_), _) => lexer.panic_message("Expected opening brace"),
+                        _ => lexer.panic_message("Expected test expression"),
+                    };
+
+                    let loop_body = BranchBody::build(lexer);
+
+                    statements.push(Statement::While {
+                        test_expr,
+                        loop_body,
+                    });
+                }
                 Token::BraceClose => break None,
                 _ => match Expr::build_start(tok, lexer) {
                     (None, Token::Semicolon | Token::BraceClose) => {}
@@ -516,6 +530,10 @@ pub enum Literal<'a> {
 pub enum Statement<'a> {
     Expr(Expr<'a>),
     If(IfStmt<'a>),
+    While {
+        test_expr: Expr<'a>,
+        loop_body: BranchBody<'a>,
+    },
     Let {
         var: &'a str,
         mutable: bool,