From 9d074ddd195b52413b609fca78745b916661279c Mon Sep 17 00:00:00 2001
From: mars <mars@tebibyte.media>
Date: Tue, 1 Mar 2022 10:06:47 -0700
Subject: [PATCH] Tail expressions, integer literal exprs

---
 src/lexer.rs |  7 +++--
 src/parse.rs | 72 ++++++++++++++++++++++++++++++++--------------------
 2 files changed, 50 insertions(+), 29 deletions(-)

diff --git a/src/lexer.rs b/src/lexer.rs
index 40c0f34..8c07890 100644
--- a/src/lexer.rs
+++ b/src/lexer.rs
@@ -57,12 +57,15 @@ pub enum Token {
     #[regex(r"[a-zA-Z_][a-zA-Z0-9_]*")]
     Identifier,
 
-    #[regex(r"0b_*[01][_01]*")]
+    #[regex(r"0b_*[01][_'01]*")]
     BinaryInteger,
 
-    #[regex(r"0o_*[0-7][_0-7]*")]
+    #[regex(r"0o_*[0-7][_'0-7]*")]
     OctalInteger,
 
+    #[regex(r"0x_*[0-9a-fA-F][_'0-9a-fA-F]*")]
+    HexInteger,
+
     #[regex(r"-?[0-9][_'0-9]*")]
     DecimalInteger,
 
diff --git a/src/parse.rs b/src/parse.rs
index 1b791ed..7275110 100644
--- a/src/parse.rs
+++ b/src/parse.rs
@@ -191,37 +191,45 @@ impl<'a> FnBody<'a> {
     pub fn build(lexer: &mut Lexer<'a>) -> Self {
         let mut statements = Vec::new();
 
-        let mut tail = Some(Token::Semicolon);
+        let mut tail_expr = None;
         loop {
-            match tail {
-                Some(Token::Semicolon) => match lexer.next().unwrap() {
-                    Token::Let => {
-                        let (statement, next) = Statement::build_let(lexer);
-                        statements.push(statement);
-                        tail = Some(next);
+            let tok = lexer.next().unwrap();
+            match tok {
+                Token::Let => {
+                    let (statement, next) = Statement::build_let(lexer);
+                    statements.push(statement);
+                    match next {
+                        Token::Semicolon => {}
+                        Token::BraceClose => break,
+                        _ => lexer.panic_message("Unexpected token"),
                     }
-                    Token::Var => {
-                        let (statement, next) = Statement::build_var(lexer);
-                        statements.push(statement);
-                        tail = Some(next);
+                }
+                Token::Var => {
+                    let (statement, next) = Statement::build_var(lexer);
+                    statements.push(statement);
+                    match next {
+                        Token::Semicolon => {}
+                        Token::BraceClose => break,
+                        _ => lexer.panic_message("Unexpected token"),
                     }
-                    Token::Identifier => {
-                        let var = lexer.slice();
-                        let (expr, next) = Statement::eat_assign(lexer);
-                        statements.push(Statement::Assign { var, expr });
-                        tail = Some(next);
+                }
+                Token::Identifier => match Expr::build_start(tok, lexer) {
+                    (None, Token::Semicolon | Token::BraceClose) => {}
+                    (Some(expr), Token::Semicolon) => statements.push(Statement::Expr(expr)),
+                    (Some(expr), Token::BraceClose) => {
+                        tail_expr = Some(expr);
+                        break;
                     }
-                    Token::BraceClose => break,
-                    _ => lexer.panic_message("Expected var, let, or assign"),
+                    _ => lexer.panic_message("Unexpected token"),
                 },
-                Some(Token::BraceClose) => break,
-                _ => lexer.panic_message("Unexpected token"),
+                Token::BraceClose => break,
+                _ => lexer.panic_message("Expected var, let, or assign"),
             }
         }
 
         Self {
             statements,
-            tail_expr: None,
+            tail_expr,
         }
     }
 }
@@ -243,11 +251,14 @@ pub enum Expr<'a> {
 }
 
 impl<'a> Expr<'a> {
-    pub fn build(lexer: &mut Lexer<'a>) -> (Option<Self>, Token) {
-        let tok = lexer.next().unwrap();
+    pub fn build_start(tok: Token, lexer: &mut Lexer<'a>) -> (Option<Self>, Token) {
         let lhs = match tok {
             Token::Identifier => Self::Local(lexer.slice()),
             Token::Dot => Self::Member(lexer.eat_expect_id()),
+            Token::BinaryInteger => Self::Literal(Literal::BinaryInteger(lexer.slice())),
+            Token::OctalInteger => Self::Literal(Literal::OctalInteger(lexer.slice())),
+            Token::HexInteger => Self::Literal(Literal::HexInteger(lexer.slice())),
+            Token::DecimalInteger => Self::Literal(Literal::DecimalInteger(lexer.slice())),
             Token::Semicolon | Token::BraceClose | Token::ParanClose => return (None, tok),
             _ => lexer.panic_message("Unexpected token"),
         };
@@ -260,6 +271,10 @@ impl<'a> Expr<'a> {
         }
     }
 
+    pub fn build(lexer: &mut Lexer<'a>) -> (Option<Self>, Token) {
+        Self::build_start(lexer.next().unwrap(), lexer)
+    }
+
     fn eat_op(lexer: &mut Lexer<'a>) -> (Option<(BinaryOp, Self)>, Token) {
         let tok = lexer.next().unwrap();
         if let Some(op) = BinaryOp::from_token(tok) {
@@ -311,15 +326,13 @@ impl BinaryOp {
 pub enum Literal<'a> {
     BinaryInteger(&'a str),
     OctalInteger(&'a str),
+    HexInteger(&'a str),
     DecimalInteger(&'a str),
 }
 
 #[derive(Debug)]
 pub enum Statement<'a> {
-    Assign {
-        var: &'a str,
-        expr: Expr<'a>,
-    },
+    Expr(Expr<'a>),
     Let {
         var: &'a str,
         expr: Expr<'a>,
@@ -406,6 +419,11 @@ mod tests {
             assert_eq!(expr.1, Token::Semicolon);
         }
 
+        #[test]
+        fn int_literals() {
+            parse_expr("0b1 + 0x2 - 0o3 * 0x4;");
+        }
+
         #[test]
         fn locals() {
             parse_expr("local1 + local2 - local3;");