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//! Types as the checker knows them, how they're shown, and which convert
//! to which without a cast (`ys-grammar.md` §8).
use std::fmt;
use super::builtin;
/// A type.
#[derive(Debug, Clone, PartialEq)]
pub enum Type {
I8,
I16,
I32,
I64,
U8,
U16,
U32,
U64,
F32,
F64,
Decimal,
Char,
Bool,
String,
/// `object`: every type converts to it.
Object,
/// `dynamic`: checked when the code runs, not here.
Dynamic,
Void,
/// `null` before it meets a type.
Null,
/// A quantity with a unit: `Ticks`, `Seconds`, `Blocks`, a mod's own.
Unit(String),
/// A content's id of a kind: an `ItemId` is `Content("item")` (`content_ids.rs`).
Content(String),
/// A tag of a content kind: a `TagId<ItemId>` is `Tag("item")`
/// (`content_ids.rs`); `""` of kinds not one.
Tag(String),
/// A type the source declares, by name, with its type arguments
/// (`Box<i32>`; none when it isn't generic).
Own(String, Vec<Type>),
/// A type parameter (`T`) where its argument isn't known: in its
/// generic's own code, or a method's before inference.
Param(String),
/// An own type named where a value goes (`Mode` in `Mode.Idle`): its
/// static members and its cases.
/// A type named where a value goes (`Math` in `Math.Max`), with the
/// type arguments written (`Comparer<i32>` in `Comparer<i32>.Default`).
Static(String, Vec<Type>),
/// A game class, by its internal name (`.yns` only).
Game(String),
/// Yog's: a handle (`Player`), a domain's group (`Chat`), a struct or
/// an enum an action answers with — by name.
Yog(String),
/// A namespace (`Game.World`), on the way to what's in it.
Namespace(String),
/// An array: `T[]` (rank 1), `T[,]` (rank 2); a Java array a game
/// class gives or takes too.
Array(Box<Type>, usize),
/// `(i32 X, string)`: its items' types, and their names where given
/// (names don't make tuple types apart: `(i32 X)` is `(i32 Y)`).
Tuple(Vec<Type>, Vec<Option<String>>),
/// A delegate: `Action<A, B>` (its result `void`), `Func<A, R>`.
Fn(Vec<Type>, Box<Type>),
Nullable(Box<Type>),
/// Not known here (the library's, or what couldn't be typed): checks
/// involving it pass, so one gap doesn't cascade.
Unknown,
}
/// The units a whole game has; a mod declares its own (`unit Energy;`).
pub use yog_script_ids::units::{BLOCKS, SECONDS, TICKS};
impl Type {
/// An own type that isn't generic.
pub fn own(name: impl Into<String>) -> Type {
Type::Own(name.into(), Vec::new())
}
pub fn nullable(self) -> Type {
match self {
Type::Nullable(_) | Type::Null | Type::Unknown => self,
other => Type::Nullable(Box::new(other)),
}
}
/// The type without its `?`.
pub fn non_null(&self) -> &Type {
match self {
Type::Nullable(t) => t,
t => t,
}
}
pub fn is_nullable(&self) -> bool {
matches!(self, Type::Nullable(_) | Type::Null)
}
pub fn known(&self) -> bool {
!matches!(self, Type::Unknown)
}
pub fn is_numeric(&self) -> bool {
builtin::is_number(self) || matches!(self, Type::Unit(_))
}
pub fn is_integer(&self) -> bool {
builtin::is_integer(self)
}
/// Whether a value of `self` goes where `to` is wanted without a cast.
pub fn converts_to(&self, to: &Type) -> bool {
if self == to || !self.known() || !to.known() {
return true;
}
if matches!(self, Type::Dynamic) || matches!(to, Type::Dynamic | Type::Object) {
return true;
}
match (self, to) {
(Type::Null, Type::Nullable(_)) => true,
(Type::Nullable(a), Type::Nullable(b)) => a.converts_to(b),
(a, Type::Nullable(b)) => a.converts_to(b),
// Quantities of different units never mix: seconds are real
// time, ticks the game's (its rate changes), made one another
// only by the game.
(Type::Unit(_), Type::Unit(_)) => false,
// A plain number is a quantity of any unit (`20` ticks), as
// literals are; quantities of different units never mix.
(n, Type::Unit(_)) => builtin::is_number(n),
(Type::Unit(_), n) => builtin::widens(&Type::I32, n),
(Type::Array(a, ra), Type::Array(b, rb)) => ra == rb && a == b,
(a, b) => builtin::widens(a, b),
}
}
/// The type both of two numbers become in an operation (`i32 + f64` is `f64`).
/// A whole number's width in bits and whether it's signed (`u8`: 8, no).
pub fn integer_width(&self) -> Option<(u32, bool)> {
builtin::integer_width(self)
}
pub fn wider(a: &Type, b: &Type) -> Type {
match (a, b) {
(Type::Unit(_), _) => a.clone(),
(_, Type::Unit(_)) => b.clone(),
_ if builtin::widens(a, b) => b.clone(),
_ => a.clone(),
}
}
}
impl fmt::Display for Type {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Type::I8
| Type::I16
| Type::I32
| Type::I64
| Type::U8
| Type::U16
| Type::U32
| Type::U64
| Type::F32
| Type::F64
| Type::Decimal
| Type::Char
| Type::Bool
| Type::String
| Type::Object
| Type::Dynamic
| Type::Void => write!(f, "{}", builtin::word(self).unwrap_or_default()),
Type::Null => write!(f, "{}", crate::words::null::WORD.text),
Type::Own(name, args) if !args.is_empty() => {
let args: Vec<_> = args.iter().map(ToString::to_string).collect();
write!(f, "{name}<{}>", args.join(", "))
}
Type::Unit(u)
| Type::Own(u, _)
| Type::Static(u, _)
| Type::Param(u)
| Type::Yog(u)
| Type::Namespace(u) => {
write!(f, "{u}")
}
Type::Content(kind) => write!(f, "{}", super::content_ids::content_id_name(kind)),
Type::Tag(kind) => write!(f, "{}", super::content_ids::tag_id_name(kind)),
Type::Game(name) => write!(f, "{}", crate::index::simple_name(name)),
// As C# writes it: the item, then the ranks outermost first
// (`i32[][,]`, an array of `i32[,]`).
Type::Array(..) => {
let mut item = self;
let mut ranks = String::new();
while let Type::Array(inner, rank) = item {
ranks.push_str(&format!("[{}]", ",".repeat(rank - 1)));
item = inner;
}
write!(f, "{item}{ranks}")
}
Type::Tuple(items, names) => {
let items: Vec<String> = items
.iter()
.zip(names.iter().chain(std::iter::repeat(&None)))
.map(|(t, n)| match n {
Some(n) => format!("{t} {n}"),
None => t.to_string(),
})
.collect();
write!(f, "({})", items.join(", "))
}
Type::Fn(params, ret) => {
let mut all: Vec<String> = params.iter().map(ToString::to_string).collect();
let word = if **ret == Type::Void {
yog_script_ids::system::ACTION
} else {
all.push(ret.to_string());
yog_script_ids::system::FUNC
};
write!(f, "{word}<{}>", all.join(", "))
}
Type::Nullable(t) => write!(f, "{t}?"),
Type::Unknown => write!(f, "?"),
}
}
}
#[cfg(test)]
mod tests;