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//! `IntStream` extension for Lexer that allows subslicing of underlying data
use std::char::REPLACEMENT_CHARACTER;
use std::convert::TryFrom;
use std::fmt::Debug;
use std::ops::{Index, Range, RangeFrom};
use crate::int_stream::IntStream;
/// Provides underlying data for Tokens.
pub trait CharStream<Data>: IntStream {
/// Returns underlying data piece, either slice or owned copy.
/// Panics if provided indexes are invalid
/// Called by parser only on token intervals.
/// This fact can be used by custom implementations
fn get_text(&self, a: isize, b: isize) -> Data;
}
/// Trait for input that can be accepted by `InputStream` to be able to provide lexer with data.
/// Public for implementation reasons.
pub trait InputData:
Index<Range<usize>, Output = Self>
+ Index<RangeFrom<usize>, Output = Self>
+ ToOwned
+ Debug
+ 'static
{
// fn to_indexed_vec(&self) -> Vec<(u32, u32)>;
#[doc(hidden)]
fn offset(&self, index: isize, item_offset: isize) -> Option<isize>;
#[doc(hidden)]
fn item(&self, index: isize) -> Option<isize>;
#[doc(hidden)]
fn len(&self) -> usize;
#[doc(hidden)]
fn from_text(text: &str) -> Self::Owned;
#[doc(hidden)]
fn to_display(&self) -> String;
}
impl<T: Into<u32> + From<u8> + TryFrom<u32> + Copy + Debug + 'static> InputData for [T]
where
<T as TryFrom<u32>>::Error: Debug,
{
// fn to_indexed_vec(&self) -> Vec<(u32, u32)> {
// self.into_iter()
// .enumerate()
// .map(|(x, &y)| (x as u32, y.into()))
// .collect()
// }
#[inline]
fn offset(&self, index: isize, item_offset: isize) -> Option<isize> {
let new_index = index + item_offset;
if new_index < 0 {
return None; // invalid; no char before first char
}
if new_index > self.len() as isize {
return None;
}
Some(new_index)
}
#[inline]
fn item(&self, index: isize) -> Option<isize> {
self.get(index as usize).map(|&it| it.into() as isize)
}
#[inline]
fn len(&self) -> usize { self.len() }
#[inline]
fn from_text(text: &str) -> Self::Owned {
text.chars()
.map(|it| T::try_from(it as u32).unwrap())
.collect()
}
#[inline]
// default
fn to_display(&self) -> String {
self.iter()
.map(|x| char::try_from((*x).into()).unwrap_or(REPLACEMENT_CHARACTER))
.collect()
}
}
//
// impl InputData for [u8] {
// #[inline]
// fn to_display(&self) -> String { String::from_utf8_lossy(self).into_owned() }
// }
// impl InputData for [u16] {
// }
//
// impl InputData for [u32] {
// #[inline]
// fn to_display(&self) -> String {
// self.iter()
// .map(|x| char::try_from(*x).unwrap_or(REPLACEMENT_CHARACTER))
// .collect()
// }
// }
impl InputData for str {
// fn to_indexed_vec(&self) -> Vec<(u32, u32)> {
// self.char_indices()
// .map(|(i, ch)| (i as u32, ch as u32))
// .collect()
// }
#[inline]
fn offset(&self, mut index: isize, mut item_offset: isize) -> Option<isize> {
if item_offset == 0 {
return Some(index);
}
let direction = item_offset.signum();
while {
index += direction;
if index < 0 || index > self.len() as isize {
return None;
}
if self.is_char_boundary(index as usize) {
item_offset -= direction;
}
item_offset != 0
} {}
Some(index)
}
#[inline]
fn item(&self, index: isize) -> Option<isize> {
self.get(index as usize..)
.and_then(|it| it.chars().next())
.map(|it| it as isize)
}
#[inline]
fn len(&self) -> usize { self.len() }
fn from_text(text: &str) -> Self::Owned { text.to_owned() }
// #[inline]
// fn from_text(text: &str) -> Self::Owned { text.to_owned() }
#[inline]
fn to_display(&self) -> String { self.to_string() }
}