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use std::fmt;
use rb_sys::VALUE;
use crate::{
error::Error,
into_value::IntoValue,
object::Object,
try_convert::TryConvert,
value::{
private::{self, ReprValue as _},
NonZeroValue, ReprValue, Value,
},
Ruby,
};
/// Wrapper type for a Value known to be an instance of Ruby's Enumerator class.
///
/// `Enumerator` implements [`Iterator`], however Rust's iterators are a pull
/// based model, whereas Ruby's enumerators are a push based model. Bridging
/// these two models incurs a performance penalty, so `Enumerator` may not be
/// the most performant way of iterating a collection.
///
/// See the [`ReprValue`] and [`Object`] traits for additional methods
/// available on this type.
///
/// # Examples
///
/// ```
/// use magnus::{prelude::*, rb_assert, Error, Ruby};
///
/// fn example(ruby: &Ruby) -> Result<(), Error> {
/// let s = ruby.str_new("foo\nbar\nbaz");
/// let results = ruby.ary_new();
///
/// // `enumeratorize` returns `Enumerator`
/// for line in s.enumeratorize("each_line", ()) {
/// results.push(line?)?;
/// }
/// rb_assert!(r#"results == ["foo\n", "bar\n", "baz"]"#, results);
///
/// Ok(())
/// }
/// # Ruby::init(example).unwrap()
/// ```
#[derive(Clone, Copy)]
#[repr(transparent)]
pub struct Enumerator(NonZeroValue);
impl Enumerator {
/// Return `Some(Enumerator)` if `val` is an `Enumerator`, `None` otherwise.
///
/// # Examples
///
/// ```
/// use magnus::{eval, Enumerator};
/// # let _cleanup = unsafe { magnus::embed::init() };
///
/// assert!(Enumerator::from_value(eval("[1, 2, 3].each").unwrap()).is_some());
/// assert!(Enumerator::from_value(eval("[1, 2, 3]").unwrap()).is_none());
/// ```
#[inline]
pub fn from_value(val: Value) -> Option<Self> {
unsafe {
val.is_kind_of(Ruby::get_with(val).class_enumerator())
.then(|| Self(NonZeroValue::new_unchecked(val)))
}
}
#[inline]
pub(crate) unsafe fn from_rb_value_unchecked(val: VALUE) -> Self {
Self(NonZeroValue::new_unchecked(Value::new(val)))
}
}
impl Iterator for Enumerator {
type Item = Result<Value, Error>;
fn next(&mut self) -> Option<Self::Item> {
match self.funcall("next", ()) {
Ok(v) => Some(Ok(v)),
Err(e) if e.is_kind_of(Ruby::get_with(*self).exception_stop_iteration()) => None,
Err(e) => Some(Err(e)),
}
}
}
impl fmt::Display for Enumerator {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{}", unsafe { self.to_s_infallible() })
}
}
impl fmt::Debug for Enumerator {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{}", ReprValue::inspect(*self))
}
}
impl IntoValue for Enumerator {
#[inline]
fn into_value_with(self, _: &Ruby) -> Value {
self.0.get()
}
}
impl Object for Enumerator {}
unsafe impl private::ReprValue for Enumerator {}
impl ReprValue for Enumerator {}
impl TryConvert for Enumerator {
fn try_convert(val: Value) -> Result<Self, Error> {
Self::from_value(val).ok_or_else(|| {
Error::new(
Ruby::get_with(val).exception_type_error(),
format!("no implicit conversion of {} into Enumerator", unsafe {
val.classname()
},),
)
})
}
}