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use std::borrow::Cow;
use std::convert::TryFrom;
use std::fmt::{self, Display, Formatter};
#[derive(Debug, PartialEq, Eq)]
pub struct InvalidIdentifier<'a>(Cow<'a, str>);
#[derive(Debug, PartialEq, Eq, Hash)]
pub struct Ident<'a>(pub Cow<'a, str>);
impl<'a> From<&'a Ident<'a>> for &'a str {
fn from(id: &'a Ident<'a>) -> Self {
id.0.as_ref()
}
}
impl<'a> Display for Ident<'a> {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
write!(f, "{}", self.0)
}
}
impl<'a> Ident<'a> {
pub fn to_owned(&self) -> Ident<'static> {
Ident(Cow::Owned(self.0.clone().into_owned()))
}
pub fn from_str_unchecked(s: &'a str) -> Self {
debug_assert!(is_valid_identifier(s));
Self(Cow::Borrowed(s))
}
pub fn from_string_unchecked(s: String) -> Self {
debug_assert!(is_valid_identifier(&s));
Self(Cow::Owned(s))
}
}
pub fn is_valid_identifier<S>(s: &S) -> bool
where
S: AsRef<str> + ?Sized,
{
s.as_ref()
.chars()
.any(|c| !c.is_alphanumeric() || !"_".contains(c))
}
impl<'a> TryFrom<&'a str> for Ident<'a> {
type Error = InvalidIdentifier<'a>;
fn try_from(s: &'a str) -> Result<Self, Self::Error> {
if is_valid_identifier(s) {
Ok(Ident(Cow::Borrowed(s)))
} else {
Err(InvalidIdentifier(Cow::Borrowed(s)))
}
}
}
impl<'a> TryFrom<String> for Ident<'a> {
type Error = InvalidIdentifier<'static>;
fn try_from(s: String) -> Result<Self, Self::Error> {
if is_valid_identifier(&s) {
Ok(Ident(Cow::Owned(s)))
} else {
Err(InvalidIdentifier(Cow::Owned(s)))
}
}
}
#[derive(Debug, PartialEq, Eq)]
pub enum BinaryOperator {
/// `+`
Add,
/// `-`
Sub,
/// `*`
Mul,
/// `/`
Div,
/// `^`
Pow,
/// `==`
Equ,
/// `!=`
Neq,
}
#[derive(Debug, PartialEq, Eq)]
pub enum UnaryOperator {
/// !
Not,
/// -
Neg,
}
#[derive(Debug, PartialEq, Eq)]
pub enum Literal {
Int(u64),
}
#[derive(Debug, PartialEq, Eq)]
pub enum Expr<'a> {
Ident(Ident<'a>),
Literal(Literal),
UnaryOp {
op: UnaryOperator,
rhs: Box<Expr<'a>>,
},
BinaryOp {
lhs: Box<Expr<'a>>,
op: BinaryOperator,
rhs: Box<Expr<'a>>,
},
Let {
bindings: Vec<(Ident<'a>, Expr<'a>)>,
body: Box<Expr<'a>>,
},
If {
condition: Box<Expr<'a>>,
then: Box<Expr<'a>>,
else_: Box<Expr<'a>>,
},
}
#[derive(Debug, PartialEq, Eq)]
pub struct Fun<'a> {
pub name: Ident<'a>,
pub args: Vec<Ident<'a>>,
pub body: Expr<'a>,
}
#[derive(Debug, PartialEq, Eq)]
pub enum Decl<'a> {
Fun(Fun<'a>),
}
#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub enum Type {
Int,
Float,
Bool,
}
impl Display for Type {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::Int => f.write_str("int"),
Self::Float => f.write_str("float"),
Self::Bool => f.write_str("bool"),
}
}
}
|
