use serde::ser::{Serialize, Serializer};
use static_assertions::assert_impl_all;
use std::fmt::Display;
use crate::{value_display_fmt, Error, Signature, Type, Value};
#[derive(Debug, Hash, PartialEq, Eq, PartialOrd, Ord)]
pub struct Maybe<'a> {
value: Box<Option<Value<'a>>>,
value_signature: Signature<'a>,
signature: Signature<'a>,
}
assert_impl_all!(Maybe<'_>: Send, Sync, Unpin);
impl<'a> Maybe<'a> {
pub fn inner(&self) -> &Option<Value<'a>> {
&self.value
}
pub fn just(value: Value<'a>) -> Self {
let value_signature = value.value_signature().to_owned();
let signature = create_signature(&value_signature);
Self {
value_signature,
signature,
value: Box::new(Some(value)),
}
}
pub(crate) fn just_full_signature<'v: 'a, 's: 'a>(
value: Value<'v>,
signature: Signature<'s>,
) -> Self {
Self {
value_signature: signature.slice(1..),
signature,
value: Box::new(Some(value)),
}
}
pub fn nothing<'s: 'a>(value_signature: Signature<'s>) -> Self {
let signature = create_signature(&value_signature);
Self {
value_signature,
signature,
value: Box::new(None),
}
}
pub(crate) fn nothing_full_signature<'s: 'a>(signature: Signature<'s>) -> Self {
Self {
value_signature: signature.slice(1..),
signature,
value: Box::new(None),
}
}
pub fn get<T>(&'a self) -> core::result::Result<Option<T>, Error>
where
T: ?Sized + TryFrom<&'a Value<'a>>,
<T as TryFrom<&'a Value<'a>>>::Error: Into<crate::Error>,
{
self.value
.as_ref()
.as_ref()
.map(|v| v.downcast_ref())
.transpose()
}
pub fn signature(&self) -> Signature<'static> {
self.signature.to_owned()
}
pub fn full_signature(&self) -> &Signature<'_> {
&self.signature
}
pub fn value_signature(&self) -> &Signature<'_> {
&self.value_signature
}
pub(crate) fn try_to_owned(&self) -> crate::Result<Maybe<'static>> {
Ok(Maybe {
value_signature: self.value_signature.to_owned(),
value: Box::new(
self.value
.as_ref()
.as_ref()
.map(|v| v.try_to_owned().map(Into::into))
.transpose()?,
),
signature: self.signature.to_owned(),
})
}
pub fn try_clone(&self) -> Result<Self, crate::Error> {
Ok(Maybe {
value_signature: self.value_signature.clone(),
value: Box::new(
self.value
.as_ref()
.as_ref()
.map(|v| v.try_clone().map(Into::into))
.transpose()?,
),
signature: self.signature.clone(),
})
}
}
impl Display for Maybe<'_> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
maybe_display_fmt(self, f, true)
}
}
pub(crate) fn maybe_display_fmt(
maybe: &Maybe<'_>,
f: &mut std::fmt::Formatter<'_>,
type_annotate: bool,
) -> std::fmt::Result {
if type_annotate {
write!(f, "@{} ", maybe.full_signature())?;
}
let (last_inner, depth) = {
let mut curr = maybe.inner();
let mut depth = 0;
while let Some(Value::Maybe(child_maybe)) = curr {
curr = child_maybe.inner();
depth += 1;
}
(curr, depth)
};
if let Some(last_inner) = last_inner {
value_display_fmt(last_inner, f, false)?;
} else {
for _ in 0..depth {
f.write_str("just ")?;
}
f.write_str("nothing")?;
}
Ok(())
}
impl<'a, T> From<Option<T>> for Maybe<'a>
where
T: Type + Into<Value<'a>>,
{
fn from(value: Option<T>) -> Self {
value
.map(|v| Self::just(Value::new(v)))
.unwrap_or_else(|| Self::nothing(T::signature()))
}
}
impl<'a, T> From<&Option<T>> for Maybe<'a>
where
T: Type + Into<Value<'a>> + Clone,
{
fn from(value: &Option<T>) -> Self {
value
.as_ref()
.map(|v| Self::just(Value::new(v.clone())))
.unwrap_or_else(|| Self::nothing(T::signature()))
}
}
impl<'a> Serialize for Maybe<'a> {
fn serialize<S>(&self, serializer: S) -> core::result::Result<S::Ok, S::Error>
where
S: Serializer,
{
match &*self.value {
Some(value) => value.serialize_value_as_some(serializer),
None => serializer.serialize_none(),
}
}
}
fn create_signature(value_signature: &Signature<'_>) -> Signature<'static> {
Signature::from_string_unchecked(format!("m{value_signature}"))
}