genmarkov/src/range.rs

//! Workarounds for ridiculously janky `std::ops::Range*` polymorphism
use super::*;
use std::{
    ops::{
	Range,
	RangeFrom,
	RangeInclusive,
	RangeTo,
	RangeToInclusive,
	RangeFull,
	
	Bound,
	RangeBounds,
    },
    str::{
	FromStr,
    },
    fmt,
    error,
};

#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub enum DynRange<T>
{
    Range(Range<T>),
    From(RangeFrom<T>),
    Inclusive(RangeInclusive<T>),
    To(RangeTo<T>),
    ToInclusive(RangeToInclusive<T>),
    Full(RangeFull),
}

#[macro_export] macro_rules! impl_from {
    (Full, RangeFull) => {
	impl<T> From<RangeFull> for DynRange<T>
	{
	    #[inline] fn from(from: RangeFull) -> Self
	    {
		Self::Full(from)
	    }
	}
    };
    ($name:ident, $range:tt) => {
	
	impl<T> From<$range <T>> for DynRange<T>
	{
	    #[inline] fn from(from: $range<T>) -> Self
	    {
		Self::$name(from)
	    }
	}
    };
}

impl_from!(Range, Range);
impl_from!(From, RangeFrom);
impl_from!(Inclusive, RangeInclusive);
impl_from!(To, RangeTo);
impl_from!(ToInclusive, RangeToInclusive);
impl_from!(Full, RangeFull);

macro_rules! bounds {
    ($self:ident, $bound:ident) => {
	match $self {
	    DynRange::Range(from) => from.$bound(),
	    DynRange::From(from) => from.$bound(),
	    DynRange::Inclusive(i) => i.$bound(),
	    DynRange::To(i) => i.$bound(),
	    DynRange::ToInclusive(i) => i.$bound(),
	    DynRange::Full(_) => (..).$bound(),
	}
    };
}

impl<T> RangeBounds<T> for DynRange<T>
{
    fn start_bound(&self) -> Bound<&T> {
	bounds!(self, start_bound)
    }
    fn end_bound(&self) -> Bound<&T> {
	bounds!(self, end_bound)
    }
}

impl<'a, T> RangeBounds<T> for &'a DynRange<T>
{
    fn start_bound(&self) -> Bound<&T> {
	bounds!(self, start_bound)
    }
    fn end_bound(&self) -> Bound<&T> {
	bounds!(self, end_bound)
    }
}

impl<T: fmt::Display> fmt::Display for DynRange<T>
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
    {
	match self {
	    Self::Range(from) => write!(f, "{}..{}", from.start, from.end),
	    Self::From(from) => write!(f, "{}..", from.start),
	    Self::Inclusive(from) => write!(f, "{}..={}", from.start(), from.end()),
	    Self::To(from) => write!(f, "..{}", from.end),
	    Self::ToInclusive(from) => write!(f, "..={}", from.end),
	    Self::Full(_) => write!(f, ".."),
	}
    }
}

use std::any::{
    Any,
};

impl<T: 'static> DynRange<T>
{
    #[inline]
    pub fn into_boxed(self) -> Box<dyn Any /*TODO: + Send + Sync */+ 'static>
    {
        self.into_inner()
    }
    fn into_inner(self) -> Box<dyn Any + 'static>
    {
	match self {
	    Self::Range(from) => Box::new(from),
	    Self::From(from) => Box::new(from),
	    Self::Inclusive(from) => Box::new(from),
	    Self::To(from) => Box::new(from),
	    Self::ToInclusive(from) => Box::new(from),
	    Self::Full(_) => Box::new(..),
	}
    }
    fn inner_mut(&mut self) -> &mut dyn Any
    {
	match self {
	    Self::Range(from) => from,
	    Self::From(from) => from,
	    Self::Inclusive(from) => from,
	    Self::To(from) => from,
	    Self::ToInclusive(from) => from,
	    Self::Full(f) => f,
	}
    }
    fn inner_ref(&self) -> &dyn Any
    {
	match self {
	    Self::Range(from) => from,
	    Self::From(from) => from,
	    Self::Inclusive(from) => from,
	    Self::To(from) => from,
	    Self::ToInclusive(from) => from,
	    Self::Full(_) => &(..),
	}
    }
    pub fn downcast_ref<R: RangeBounds<T> + 'static>(&self) -> Option<&R>
    {
	self.inner_ref().downcast_ref()
    }
    pub fn downcast_mut<R: RangeBounds<T> + 'static>(&mut self) -> Option<&mut R>
    {
	self.inner_mut().downcast_mut()
    }
    pub fn downcast<R: RangeBounds<T> + 'static>(self) -> Result<R, Self>
    {
	self.into_inner().downcast::<R>()
		.map(|x| *x)
		.map_err(|b| {
		    todo!("make this bullshit properly unboxable ehh...")
        })
	//Box::<(dyn std::any::Any + 'static)>::downcast(Box::new(self)).map_ok(|ok| *ok)
    }			
}

#[derive(Debug)]
pub struct ParseError(DynRange<()>, Option<Box<dyn error::Error+'static>>);

impl ParseError
{
    fn new<R: Into<DynRange<()>>>(which: R, err: impl error::Error + 'static) -> Self
    {
	Self(which.into(), Some(Box::new(err)))
    }
    fn none(which: impl Into<DynRange<()>>) -> Self
    {
	Self(which.into(), None)
    }
    fn map<T: Into<DynRange<()>>>(self, to: T) -> Self
    {
	Self (to.into(), self.1)
    }
}

impl error::Error for ParseError
{
    fn source(&self) -> Option<&(dyn error::Error + 'static)> {
	if let Some(this) = self.1.as_ref() {
	    Some(this.as_ref())
	} else {
	    None
	}
    }
}

impl fmt::Display for ParseError
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
    {
	write!(f, "failed to parse range in format `{:?}`", self.0)?;
	if let Some(this) = self.1.as_ref() {
	    write!(f, ": {}", this)?;
	}
	Ok(())
    }
}


impl<T: FromStr> FromStr for DynRange<T>
where T::Err: error::Error + 'static
{
    type Err = ParseError;
    fn from_str(s: &str) -> Result<Self, Self::Err> {
	if s== ".." {
	    Ok(Self::Full(..))
	} else if s.starts_with("..=") {
	    Ok(Self::ToInclusive(..=T::from_str(&s[3..]).map_err(|x| ParseError::new(..=(), x))?))
	} else if s.starts_with("..") {
	    Ok(Self::To(..(T::from_str(&s[2..])).map_err(|x| ParseError::new(..(), x))?))
	} else if s.ends_with("..") {
	    Ok(Self::From(T::from_str(&s[..s.len()-2]).map_err(|x| ParseError::new(().., x))?..))
	} else {
	    fn try_next_incl<'a, T: FromStr>(m: &mut impl Iterator<Item=&'a str>) -> Result<RangeInclusive<T>, ParseError>
	    where T::Err: error::Error + 'static
	    {
		let (first, second) = if let Some(first) = m.next() {
		    if let Some(seocond) = m.next() {
			(first,seocond)
		    } else {
			return Err(ParseError::none(()..=()));
		    }
		} else {
		    return Err(ParseError::none(()..=()));
		};

		let first: T = first.parse().map_err(|x| ParseError::new(()..=(), x))?;
		let second: T = second.parse().map_err(|x| ParseError::new(()..=(), x))?;

		Ok(first..=second)
	    }

	    fn try_next<'a, T: FromStr>(m: &mut impl Iterator<Item=&'a str>) -> Result<Range<T>, ParseError>
	    where T::Err: error::Error + 'static
	    {
		let (first, second) = if let Some(first) = m.next() {
		    if let Some(seocond) = m.next() {
			(first,seocond)
		    } else {
			return Err(ParseError::none(()..()));
		    }
		} else {
		    return Err(ParseError::none(()..()));
		};

		let first: T = first.parse().map_err(|x| ParseError::new(()..(), x))?;
		let second: T = second.parse().map_err(|x| ParseError::new(()..(), x))?;

		Ok(first..second)
	    }

	    
	    let mut split = s.split("..=").fuse();

	    let mut last_err = ParseError::none(()..());
	    match loop {
		match try_next_incl(&mut split) {
		    Err(ParseError(_, None)) => break Err(last_err), // iter empty
		    Err(other) => last_err = other,
		    Ok(value) => break Ok(Self::Inclusive(value)),
		}
	    } {
		Ok(v) => return Ok(v),
		Err(e) => last_err = e,
	    };
	    
	    let mut split = s.split("..").fuse();
	    match loop {
		match try_next(&mut split) {
		    Err(ParseError(_, None)) => break Err(last_err), // iter empty
		    Err(other) => last_err = other,
		    Ok(value) => break Ok(Self::Range(value)),
		}
	    } {
		Ok(v) => Ok(v),
		Err(e) => Err(e),
	    }
	}
    }
}