From 999b25df8b74e0af9c6b754ecee7bbefc093db49 Mon Sep 17 00:00:00 2001
From: Jakub Doka <jakub.doka2@gmail.com>
Date: Sun, 3 Nov 2024 22:27:37 +0100
Subject: [PATCH] adding '_ = <expr>' syntax

---
 lang/README.md     | 4 ++--
 lang/src/fmt.rs    | 1 +
 lang/src/lexer.rs  | 2 ++
 lang/src/parser.rs | 4 ++++
 lang/src/son.rs    | 4 ++++
 5 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/lang/README.md b/lang/README.md
index 90606ca..1fb8821 100644
--- a/lang/README.md
+++ b/lang/README.md
@@ -1008,9 +1008,9 @@ create_back_buffer := fn(total_pages: int): ^u32 {
 	remaining := total_pages - 0xFF
 	loop if remaining <= 0 break else {
 		if remaining < 0xFF {
-			_f := request_page(@intcast(remaining))
+			_ = request_page(@intcast(remaining))
 		} else {
-			_f := request_page(0xFF)
+			_ = request_page(0xFF)
 		}
 		remaining -= 0xFF
 	}
diff --git a/lang/src/fmt.rs b/lang/src/fmt.rs
index 57a2dcb..773561b 100644
--- a/lang/src/fmt.rs
+++ b/lang/src/fmt.rs
@@ -346,6 +346,7 @@ impl<'a> Formatter<'a> {
                 self.fmt(val, f)
             }
             Expr::Return { val: None, .. } => f.write_str("return"),
+            Expr::Wildcard { .. } => f.write_str("_"),
             Expr::Ident { pos, is_ct, .. } => {
                 if is_ct {
                     f.write_str("$")?;
diff --git a/lang/src/lexer.rs b/lang/src/lexer.rs
index 9996357..f68a63e 100644
--- a/lang/src/lexer.rs
+++ b/lang/src/lexer.rs
@@ -148,6 +148,7 @@ pub enum TokenKind {
     RBrack = b']',
     Xor = b'^',
     Tick = b'`',
+    Under = b'_',
     // Unused = a-z
     LBrace = b'{',
     Bor = b'|',
@@ -308,6 +309,7 @@ gen_token_kind! {
         Null      = b"null",
         Idk       = b"idk",
         Die       = b"die",
+        Under     = b"_",
         #[punkt]
         Ctor   = ".{",
         Tupl   = ".(",
diff --git a/lang/src/parser.rs b/lang/src/parser.rs
index e8c9e57..7995eef 100644
--- a/lang/src/parser.rs
+++ b/lang/src/parser.rs
@@ -392,6 +392,7 @@ impl<'a, 'b> Parser<'a, 'b> {
                 let (id, is_first) = self.resolve_ident(token);
                 E::Ident { pos, is_ct: token.kind == T::CtIdent, id, is_first }
             }
+            T::Under => E::Wildcard { pos },
             T::If => E::If {
                 pos,
                 cond: self.ptr_expr()?,
@@ -800,6 +801,9 @@ generate_expr! {
             pos: Pos,
             val: Option<&'a Self>,
         },
+        Wildcard {
+            pos: Pos,
+        },
         /// note: ':unicode:' is any utf-8 character except ascii
         /// `'[a-zA-Z_:unicode:][a-zA-Z0-9_:unicode:]*'`
         Ident {
diff --git a/lang/src/son.rs b/lang/src/son.rs
index 351ff94..b95b1bb 100644
--- a/lang/src/son.rs
+++ b/lang/src/son.rs
@@ -2666,6 +2666,10 @@ impl<'a> Codegen<'a> {
                 self.assign_pattern(left, right);
                 Some(Value::VOID)
             }
+            Expr::BinOp { left: Expr::Wildcard { .. }, op: TokenKind::Assign, right, .. } => {
+                self.expr(right)?;
+                Some(Value::VOID)
+            }
             Expr::BinOp { left, pos, op: TokenKind::Assign, right } => {
                 let dest = self.raw_expr(left)?;
                 let mut value = self.expr_ctx(right, Ctx::default().with_ty(dest.ty))?;