Lower values of char and byte literals

crates/syntax/src/ast/expr_ext.rs

@@ -283,8 +283,8 @@ pub enum LiteralKind {
     ByteString(ast::ByteString),
     IntNumber(ast::IntNumber),
     FloatNumber(ast::FloatNumber),
-    Char,
-    Byte,
+    Char(ast::Char),
+    Byte(ast::Byte),
     Bool(bool),
 }
 
@@ -312,12 +312,16 @@ impl ast::Literal {
         if let Some(t) = ast::ByteString::cast(token.clone()) {
             return LiteralKind::ByteString(t);
         }
+        if let Some(t) = ast::Char::cast(token.clone()) {
+            return LiteralKind::Char(t);
+        }
+        if let Some(t) = ast::Byte::cast(token.clone()) {
+            return LiteralKind::Byte(t);
+        }
 
         match token.kind() {
             T![true] => LiteralKind::Bool(true),
             T![false] => LiteralKind::Bool(false),
-            CHAR => LiteralKind::Char,
-            BYTE => LiteralKind::Byte,
             _ => unreachable!(),
         }
     }

crates/syntax/src/ast/generated/tokens.rs

@@ -132,6 +132,48 @@ impl AstToken for FloatNumber {
     fn syntax(&self) -> &SyntaxToken { &self.syntax }
 }
 
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct Char {
+    pub(crate) syntax: SyntaxToken,
+}
+impl std::fmt::Display for Char {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        std::fmt::Display::fmt(&self.syntax, f)
+    }
+}
+impl AstToken for Char {
+    fn can_cast(kind: SyntaxKind) -> bool { kind == CHAR }
+    fn cast(syntax: SyntaxToken) -> Option<Self> {
+        if Self::can_cast(syntax.kind()) {
+            Some(Self { syntax })
+        } else {
+            None
+        }
+    }
+    fn syntax(&self) -> &SyntaxToken { &self.syntax }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct Byte {
+    pub(crate) syntax: SyntaxToken,
+}
+impl std::fmt::Display for Byte {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        std::fmt::Display::fmt(&self.syntax, f)
+    }
+}
+impl AstToken for Byte {
+    fn can_cast(kind: SyntaxKind) -> bool { kind == BYTE }
+    fn cast(syntax: SyntaxToken) -> Option<Self> {
+        if Self::can_cast(syntax.kind()) {
+            Some(Self { syntax })
+        } else {
+            None
+        }
+    }
+    fn syntax(&self) -> &SyntaxToken { &self.syntax }
+}
+
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct Ident {
     pub(crate) syntax: SyntaxToken,

crates/syntax/src/ast/token_ext.rs

@@ -2,7 +2,7 @@
 
 use std::borrow::Cow;
 
-use rustc_lexer::unescape::{unescape_literal, Mode};
+use rustc_lexer::unescape::{unescape_byte, unescape_char, unescape_literal, Mode};
 
 use crate::{
     ast::{self, AstToken},
@@ -406,3 +406,35 @@ mod tests {
         check_string_value(r"C:\\Windows\\System32\\", "C:\\Windows\\System32\\");
     }
 }
+
+impl ast::Char {
+    pub fn value(&self) -> Option<char> {
+        let mut text = self.text();
+        if text.starts_with('\'') {
+            text = &text[1..];
+        } else {
+            return None;
+        }
+        if text.ends_with('\'') {
+            text = &text[0..text.len() - 1];
+        }
+
+        unescape_char(text).ok()
+    }
+}
+
+impl ast::Byte {
+    pub fn value(&self) -> Option<u8> {
+        let mut text = self.text();
+        if text.starts_with("b\'") {
+            text = &text[2..];
+        } else {
+            return None;
+        }
+        if text.ends_with('\'') {
+            text = &text[0..text.len() - 1];
+        }
+
+        unescape_byte(text).ok()
+    }
+}