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use crate::ast;
use crate::{Parse, ParseError, Parser, Peeker, Spanned, Storage, ToTokens};
use runestick::Span;
/// A literal value
#[derive(Debug, Clone, PartialEq, Eq, ToTokens, Spanned)]
pub enum Lit {
/// A boolean literal
Bool(ast::LitBool),
/// A byte literal
Byte(ast::LitByte),
/// A string literal
Str(ast::LitStr),
/// A byte string literal
ByteStr(ast::LitByteStr),
/// A character literal
Char(ast::LitChar),
/// A number literal
Number(ast::LitNumber),
}
impl Lit {
/// Construct a new literal.
///
/// # Panics
///
/// This will panic if it's called outside of a macro context.
pub fn new<T>(lit: T) -> Self
where
T: crate::macros::IntoLit,
{
crate::macros::current_context(|ctx| Self::new_with(lit, ctx.macro_span(), ctx.storage()))
}
/// Construct a new literal with the specified span and storage.
///
/// This does not panic outside of a macro context, but requires access to
/// the specified arguments.
///
/// # Examples
///
/// ```rust
/// use rune::{ast, Storage};
/// use runestick::Span;
///
/// let storage = Storage::default();
/// let string = ast::Lit::new_with("hello world", Span::empty(), &storage);
/// ```
pub fn new_with<T>(lit: T, span: Span, storage: &Storage) -> Self
where
T: crate::macros::IntoLit,
{
T::into_lit(lit, span, storage)
}
/// Test if this is an immediate literal in an expression.
///
/// Here we only test for unambiguous literals which will not be caused by
/// a later stage as an expression is being parsed.
///
/// These include:
/// * Object literals that start with a path (handled in [ast::Expr::parse_with_meta_path]).
/// * Tuple literals that start with a path (handled in [ast::Expr::parse_open_paren]).
pub(crate) fn peek_in_expr(p: &mut Peeker<'_>) -> bool {
match p.nth(0) {
K![true] | K![false] => true,
K![byte] => true,
K![number] => true,
K![char] => true,
K![str] => true,
K![bytestr] => true,
_ => false,
}
}
}
/// Parsing a Lit
///
/// # Examples
///
/// ```rust
/// use rune::{testing, ast};
///
/// testing::roundtrip::<ast::Lit>("true");
/// testing::roundtrip::<ast::Lit>("false");
/// testing::roundtrip::<ast::Lit>("'🔥'");
/// testing::roundtrip::<ast::Lit>("b'4'");
/// testing::roundtrip::<ast::Lit>("b\"bytes\"");
/// testing::roundtrip::<ast::Lit>("1.2");
/// testing::roundtrip::<ast::Lit>("42");
/// testing::roundtrip::<ast::Lit>("\"mary had a little lamb\"");
/// ```
impl Parse for Lit {
fn parse(p: &mut Parser<'_>) -> Result<Self, ParseError> {
match p.nth(0)? {
K![true] | K![false] => return Ok(Lit::Bool(p.parse()?)),
K![byte(_)] => return Ok(Lit::Byte(p.parse()?)),
K![number(_)] => return Ok(Lit::Number(p.parse()?)),
K![char(_)] => return Ok(Lit::Char(p.parse()?)),
K![str(_)] => return Ok(Lit::Str(p.parse()?)),
K![bytestr(_)] => return Ok(Lit::ByteStr(p.parse()?)),
_ => (),
}
Err(ParseError::expected(
&p.next()?,
r#"expected literal like `"Hello World"` or 42"#,
))
}
}