add true and false as keywords

src/ast/data/token.rs

@@ -15,6 +15,8 @@ pub enum Token {
   KwConst,
   #[regex(r"continue", priority = 4)]
   KwContinue,
+  #[regex(r"false", priority = 4)]
+  KwFalse,
   #[regex(r"fn", priority = 4)]
   KwFn,
   #[regex(r"if", priority = 4)]
@@ -27,6 +29,8 @@ pub enum Token {
   KwReturn,
   #[regex(r"static", priority = 4)]
   KwStatic,
+  #[regex(r"true", priority = 4)]
+  KwTrue,
 
   #[regex(r"\[", priority = 3)]
   OpBracket,
@@ -226,6 +230,8 @@ impl core::fmt::Display for Token {
       Token::GreaterThan => write!(f, ">"),
       Token::LessThan => write!(f, "<"),
       Token::Ampersand => write!(f, "&"),
+      Token::KwFalse => write!(f, "false"),
+      Token::KwTrue => write!(f, "true"),
     }
   }
 }

src/ast/parsing/lone_tokens.rs

@@ -1,7 +1,8 @@
 //! Parsing of individual [TokenTree::Lone] token values.
 //!
-//! * Notably: [`num_lit_p`], [`ident_p`], and [`register_p`] can match against
-//!   varying inputs, and the captured input is [FileSpanned] as their output.
+//! * The [`num_lit_p`], [`ident_p`], [`register_p`], and [`bool_p`] parsers can
+//!   match against varying inputs, and the captured input is [FileSpanned] as
+//!   their output.
 //! * The rest of them only parse for exactly one value (eg: a single period or
 //!   a single comma), and so all those parsers output nothing.
 
@@ -57,6 +58,20 @@ where
   .as_context()
 }
 
+/// Parses either `Lone(bool)` value.
+pub fn bool_p<'src, I>(
+) -> impl Parser<'src, I, FileSpanned<bool>, ErrRichTokenTree<'src>> + Clone
+where
+  I: BorrowInput<'src, Token = TokenTree, Span = FileSpan> + ValueInput<'src>,
+{
+  select! {
+    Lone(KwTrue) = ex => FileSpanned::new(true, ex.span()),
+    Lone(KwFalse) = ex => FileSpanned::new(false, ex.span()),
+  }
+  .labelled("bool")
+  .as_context()
+}
+
 /// Parses a `Lone(KwBreak)`, which is then discarded.
 pub fn kw_break_p<'src, I>(
 ) -> impl Parser<'src, I, (), ErrRichTokenTree<'src>> + Clone