Rename Red Knot (#17820)

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Micha Reiser 2025-05-03 19:49:15 +02:00 committed by GitHub
parent e6a798b962
commit b51c4f82ea
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1564 changed files with 1598 additions and 1578 deletions

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pub(crate) mod subscript;

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//! This module provides utility functions for indexing (`PyIndex`) and slicing
//! operations (`PySlice`) on iterators, following the semantics of equivalent
//! operations in Python.
use itertools::Either;
#[derive(Debug, Clone, Copy, PartialEq)]
pub(crate) struct OutOfBoundsError;
pub(crate) trait PyIndex {
type Item;
fn py_index(&mut self, index: i32) -> Result<Self::Item, OutOfBoundsError>;
}
fn from_nonnegative_i32(index: i32) -> usize {
static_assertions::const_assert!(usize::BITS >= 32);
debug_assert!(index >= 0);
usize::try_from(index)
.expect("Should only ever pass a positive integer to `from_nonnegative_i32`")
}
fn from_negative_i32(index: i32) -> usize {
static_assertions::const_assert!(usize::BITS >= 32);
index.checked_neg().map(from_nonnegative_i32).unwrap_or({
// 'checked_neg' only fails for i32::MIN. We can not
// represent -i32::MIN as a i32, but we can represent
// it as a usize, since usize is at least 32 bits.
from_nonnegative_i32(i32::MAX) + 1
})
}
#[derive(Debug, Clone, Copy, PartialEq, PartialOrd)]
enum Position {
BeforeStart,
AtIndex(usize),
AfterEnd,
}
enum Nth {
FromStart(usize),
FromEnd(usize),
}
impl Nth {
fn from_index(index: i32) -> Self {
if index >= 0 {
Nth::FromStart(from_nonnegative_i32(index))
} else {
Nth::FromEnd(from_negative_i32(index) - 1)
}
}
fn to_position(&self, len: usize) -> Position {
debug_assert!(len > 0);
match self {
Nth::FromStart(nth) => {
if *nth < len {
Position::AtIndex(*nth)
} else {
Position::AfterEnd
}
}
Nth::FromEnd(nth_rev) => {
if *nth_rev < len {
Position::AtIndex(len - 1 - *nth_rev)
} else {
Position::BeforeStart
}
}
}
}
}
impl<I, T> PyIndex for T
where
T: DoubleEndedIterator<Item = I>,
{
type Item = I;
fn py_index(&mut self, index: i32) -> Result<I, OutOfBoundsError> {
match Nth::from_index(index) {
Nth::FromStart(nth) => self.nth(nth).ok_or(OutOfBoundsError),
Nth::FromEnd(nth_rev) => self.nth_back(nth_rev).ok_or(OutOfBoundsError),
}
}
}
#[derive(Debug, Clone, Copy, PartialEq)]
pub(crate) struct StepSizeZeroError;
pub(crate) trait PySlice {
type Item;
fn py_slice(
&self,
start: Option<i32>,
stop: Option<i32>,
step: Option<i32>,
) -> Result<
Either<impl Iterator<Item = &Self::Item>, impl Iterator<Item = &Self::Item>>,
StepSizeZeroError,
>;
}
impl<T> PySlice for [T] {
type Item = T;
fn py_slice(
&self,
start: Option<i32>,
stop: Option<i32>,
step_int: Option<i32>,
) -> Result<
Either<impl Iterator<Item = &Self::Item>, impl Iterator<Item = &Self::Item>>,
StepSizeZeroError,
> {
let step_int = step_int.unwrap_or(1);
if step_int == 0 {
return Err(StepSizeZeroError);
}
let len = self.len();
if len == 0 {
// The iterator needs to have the same type as the step>0 case below,
// so we need to use `.skip(0)`.
#[allow(clippy::iter_skip_zero)]
return Ok(Either::Left(self.iter().skip(0).take(0).step_by(1)));
}
let to_position = |index| Nth::from_index(index).to_position(len);
if step_int.is_positive() {
let step = from_nonnegative_i32(step_int);
let start = start.map(to_position).unwrap_or(Position::BeforeStart);
let stop = stop.map(to_position).unwrap_or(Position::AfterEnd);
let (skip, take, step) = if start < stop {
let skip = match start {
Position::BeforeStart => 0,
Position::AtIndex(start_index) => start_index,
Position::AfterEnd => len,
};
let take = match stop {
Position::BeforeStart => 0,
Position::AtIndex(stop_index) => stop_index - skip,
Position::AfterEnd => len - skip,
};
(skip, take, step)
} else {
(0, 0, step)
};
Ok(Either::Left(
self.iter().skip(skip).take(take).step_by(step),
))
} else {
let step = from_negative_i32(step_int);
let start = start.map(to_position).unwrap_or(Position::AfterEnd);
let stop = stop.map(to_position).unwrap_or(Position::BeforeStart);
let (skip, take, step) = if start <= stop {
(0, 0, step)
} else {
let skip = match start {
Position::BeforeStart => len,
Position::AtIndex(start_index) => len - 1 - start_index,
Position::AfterEnd => 0,
};
let take = match stop {
Position::BeforeStart => len - skip,
Position::AtIndex(stop_index) => (len - 1) - skip - stop_index,
Position::AfterEnd => 0,
};
(skip, take, step)
};
Ok(Either::Right(
self.iter().rev().skip(skip).take(take).step_by(step),
))
}
}
}
#[cfg(test)]
#[allow(clippy::redundant_clone)]
mod tests {
use crate::util::subscript::{OutOfBoundsError, StepSizeZeroError};
use super::{PyIndex, PySlice};
use itertools::assert_equal;
#[test]
fn py_index_empty() {
let iter = std::iter::empty::<char>();
assert_eq!(iter.clone().py_index(0), Err(OutOfBoundsError));
assert_eq!(iter.clone().py_index(1), Err(OutOfBoundsError));
assert_eq!(iter.clone().py_index(-1), Err(OutOfBoundsError));
assert_eq!(iter.clone().py_index(i32::MIN), Err(OutOfBoundsError));
assert_eq!(iter.clone().py_index(i32::MAX), Err(OutOfBoundsError));
}
#[test]
fn py_index_single_element() {
let iter = ['a'].into_iter();
assert_eq!(iter.clone().py_index(0), Ok('a'));
assert_eq!(iter.clone().py_index(1), Err(OutOfBoundsError));
assert_eq!(iter.clone().py_index(-1), Ok('a'));
assert_eq!(iter.clone().py_index(-2), Err(OutOfBoundsError));
}
#[test]
fn py_index_more_elements() {
let iter = ['a', 'b', 'c', 'd', 'e'].into_iter();
assert_eq!(iter.clone().py_index(0), Ok('a'));
assert_eq!(iter.clone().py_index(1), Ok('b'));
assert_eq!(iter.clone().py_index(4), Ok('e'));
assert_eq!(iter.clone().py_index(5), Err(OutOfBoundsError));
assert_eq!(iter.clone().py_index(-1), Ok('e'));
assert_eq!(iter.clone().py_index(-2), Ok('d'));
assert_eq!(iter.clone().py_index(-5), Ok('a'));
assert_eq!(iter.clone().py_index(-6), Err(OutOfBoundsError));
}
#[test]
fn py_index_uses_full_index_range() {
let iter = 0..=u32::MAX;
// u32::MAX - |i32::MIN| + 1 = 2^32 - 1 - 2^31 + 1 = 2^31
assert_eq!(iter.clone().py_index(i32::MIN), Ok(2u32.pow(31)));
assert_eq!(iter.clone().py_index(-2), Ok(u32::MAX - 2 + 1));
assert_eq!(iter.clone().py_index(-1), Ok(u32::MAX - 1 + 1));
assert_eq!(iter.clone().py_index(0), Ok(0));
assert_eq!(iter.clone().py_index(1), Ok(1));
assert_eq!(iter.clone().py_index(i32::MAX), Ok(i32::MAX as u32));
}
#[track_caller]
fn assert_eq_slice<const N: usize, const M: usize>(
input: &[char; N],
start: Option<i32>,
stop: Option<i32>,
step: Option<i32>,
expected: &[char; M],
) {
assert_equal(input.py_slice(start, stop, step).unwrap(), expected.iter());
}
#[test]
fn py_slice_empty_input() {
let input = [];
assert_eq_slice(&input, None, None, None, &[]);
assert_eq_slice(&input, Some(0), None, None, &[]);
assert_eq_slice(&input, None, Some(0), None, &[]);
assert_eq_slice(&input, Some(0), Some(0), None, &[]);
assert_eq_slice(&input, Some(-5), Some(-5), None, &[]);
assert_eq_slice(&input, None, None, Some(-1), &[]);
assert_eq_slice(&input, None, None, Some(2), &[]);
}
#[test]
fn py_slice_single_element_input() {
let input = ['a'];
assert_eq_slice(&input, None, None, None, &['a']);
assert_eq_slice(&input, Some(0), None, None, &['a']);
assert_eq_slice(&input, None, Some(0), None, &[]);
assert_eq_slice(&input, Some(0), Some(0), None, &[]);
assert_eq_slice(&input, Some(0), Some(1), None, &['a']);
assert_eq_slice(&input, Some(0), Some(2), None, &['a']);
assert_eq_slice(&input, Some(-1), None, None, &['a']);
assert_eq_slice(&input, Some(-1), Some(-1), None, &[]);
assert_eq_slice(&input, Some(-1), Some(0), None, &[]);
assert_eq_slice(&input, Some(-1), Some(1), None, &['a']);
assert_eq_slice(&input, Some(-1), Some(2), None, &['a']);
assert_eq_slice(&input, None, Some(-1), None, &[]);
assert_eq_slice(&input, Some(-2), None, None, &['a']);
assert_eq_slice(&input, Some(-2), Some(-1), None, &[]);
assert_eq_slice(&input, Some(-2), Some(0), None, &[]);
assert_eq_slice(&input, Some(-2), Some(1), None, &['a']);
assert_eq_slice(&input, Some(-2), Some(2), None, &['a']);
}
#[test]
fn py_slice_nonnegative_indices() {
let input = ['a', 'b', 'c', 'd', 'e'];
assert_eq_slice(&input, None, Some(0), None, &[]);
assert_eq_slice(&input, None, Some(1), None, &['a']);
assert_eq_slice(&input, None, Some(4), None, &['a', 'b', 'c', 'd']);
assert_eq_slice(&input, None, Some(5), None, &['a', 'b', 'c', 'd', 'e']);
assert_eq_slice(&input, None, Some(6), None, &['a', 'b', 'c', 'd', 'e']);
assert_eq_slice(&input, None, None, None, &['a', 'b', 'c', 'd', 'e']);
assert_eq_slice(&input, Some(0), Some(0), None, &[]);
assert_eq_slice(&input, Some(0), Some(1), None, &['a']);
assert_eq_slice(&input, Some(0), Some(4), None, &['a', 'b', 'c', 'd']);
assert_eq_slice(&input, Some(0), Some(5), None, &['a', 'b', 'c', 'd', 'e']);
assert_eq_slice(&input, Some(0), Some(6), None, &['a', 'b', 'c', 'd', 'e']);
assert_eq_slice(&input, Some(0), None, None, &['a', 'b', 'c', 'd', 'e']);
assert_eq_slice(&input, Some(1), Some(0), None, &[]);
assert_eq_slice(&input, Some(1), Some(1), None, &[]);
assert_eq_slice(&input, Some(1), Some(2), None, &['b']);
assert_eq_slice(&input, Some(1), Some(4), None, &['b', 'c', 'd']);
assert_eq_slice(&input, Some(1), Some(5), None, &['b', 'c', 'd', 'e']);
assert_eq_slice(&input, Some(1), Some(6), None, &['b', 'c', 'd', 'e']);
assert_eq_slice(&input, Some(1), None, None, &['b', 'c', 'd', 'e']);
assert_eq_slice(&input, Some(4), Some(0), None, &[]);
assert_eq_slice(&input, Some(4), Some(4), None, &[]);
assert_eq_slice(&input, Some(4), Some(5), None, &['e']);
assert_eq_slice(&input, Some(4), Some(6), None, &['e']);
assert_eq_slice(&input, Some(4), None, None, &['e']);
assert_eq_slice(&input, Some(5), Some(0), None, &[]);
assert_eq_slice(&input, Some(5), Some(5), None, &[]);
assert_eq_slice(&input, Some(5), Some(6), None, &[]);
assert_eq_slice(&input, Some(5), None, None, &[]);
assert_eq_slice(&input, Some(6), Some(0), None, &[]);
assert_eq_slice(&input, Some(6), Some(6), None, &[]);
assert_eq_slice(&input, Some(6), None, None, &[]);
}
#[test]
fn py_slice_negatice_indices() {
let input = ['a', 'b', 'c', 'd', 'e'];
assert_eq_slice(&input, Some(-6), None, None, &['a', 'b', 'c', 'd', 'e']);
assert_eq_slice(&input, Some(-6), Some(-1), None, &['a', 'b', 'c', 'd']);
assert_eq_slice(&input, Some(-6), Some(-4), None, &['a']);
assert_eq_slice(&input, Some(-6), Some(-5), None, &[]);
assert_eq_slice(&input, Some(-6), Some(-6), None, &[]);
assert_eq_slice(&input, Some(-6), Some(-10), None, &[]);
assert_eq_slice(&input, Some(-5), None, None, &['a', 'b', 'c', 'd', 'e']);
assert_eq_slice(&input, Some(-5), Some(-1), None, &['a', 'b', 'c', 'd']);
assert_eq_slice(&input, Some(-5), Some(-4), None, &['a']);
assert_eq_slice(&input, Some(-5), Some(-5), None, &[]);
assert_eq_slice(&input, Some(-5), Some(-6), None, &[]);
assert_eq_slice(&input, Some(-5), Some(-10), None, &[]);
assert_eq_slice(&input, Some(-4), None, None, &['b', 'c', 'd', 'e']);
assert_eq_slice(&input, Some(-4), Some(-1), None, &['b', 'c', 'd']);
assert_eq_slice(&input, Some(-4), Some(-3), None, &['b']);
assert_eq_slice(&input, Some(-4), Some(-4), None, &[]);
assert_eq_slice(&input, Some(-4), Some(-10), None, &[]);
assert_eq_slice(&input, Some(-1), None, None, &['e']);
assert_eq_slice(&input, Some(-1), Some(-1), None, &[]);
assert_eq_slice(&input, Some(-1), Some(-10), None, &[]);
assert_eq_slice(&input, None, Some(-1), None, &['a', 'b', 'c', 'd']);
assert_eq_slice(&input, None, Some(-4), None, &['a']);
assert_eq_slice(&input, None, Some(-5), None, &[]);
assert_eq_slice(&input, None, Some(-6), None, &[]);
}
#[test]
fn py_slice_mixed_positive_negative_indices() {
let input = ['a', 'b', 'c', 'd', 'e'];
assert_eq_slice(&input, Some(0), Some(-1), None, &['a', 'b', 'c', 'd']);
assert_eq_slice(&input, Some(1), Some(-1), None, &['b', 'c', 'd']);
assert_eq_slice(&input, Some(3), Some(-1), None, &['d']);
assert_eq_slice(&input, Some(4), Some(-1), None, &[]);
assert_eq_slice(&input, Some(5), Some(-1), None, &[]);
assert_eq_slice(&input, Some(0), Some(-4), None, &['a']);
assert_eq_slice(&input, Some(1), Some(-4), None, &[]);
assert_eq_slice(&input, Some(3), Some(-4), None, &[]);
assert_eq_slice(&input, Some(0), Some(-5), None, &[]);
assert_eq_slice(&input, Some(1), Some(-5), None, &[]);
assert_eq_slice(&input, Some(3), Some(-5), None, &[]);
assert_eq_slice(&input, Some(0), Some(-6), None, &[]);
assert_eq_slice(&input, Some(1), Some(-6), None, &[]);
assert_eq_slice(&input, Some(-6), Some(6), None, &['a', 'b', 'c', 'd', 'e']);
assert_eq_slice(&input, Some(-6), Some(5), None, &['a', 'b', 'c', 'd', 'e']);
assert_eq_slice(&input, Some(-6), Some(4), None, &['a', 'b', 'c', 'd']);
assert_eq_slice(&input, Some(-6), Some(1), None, &['a']);
assert_eq_slice(&input, Some(-6), Some(0), None, &[]);
assert_eq_slice(&input, Some(-5), Some(6), None, &['a', 'b', 'c', 'd', 'e']);
assert_eq_slice(&input, Some(-5), Some(5), None, &['a', 'b', 'c', 'd', 'e']);
assert_eq_slice(&input, Some(-5), Some(4), None, &['a', 'b', 'c', 'd']);
assert_eq_slice(&input, Some(-5), Some(1), None, &['a']);
assert_eq_slice(&input, Some(-5), Some(0), None, &[]);
assert_eq_slice(&input, Some(-4), Some(6), None, &['b', 'c', 'd', 'e']);
assert_eq_slice(&input, Some(-4), Some(5), None, &['b', 'c', 'd', 'e']);
assert_eq_slice(&input, Some(-4), Some(4), None, &['b', 'c', 'd']);
assert_eq_slice(&input, Some(-4), Some(2), None, &['b']);
assert_eq_slice(&input, Some(-4), Some(1), None, &[]);
assert_eq_slice(&input, Some(-4), Some(0), None, &[]);
assert_eq_slice(&input, Some(-1), Some(6), None, &['e']);
assert_eq_slice(&input, Some(-1), Some(5), None, &['e']);
assert_eq_slice(&input, Some(-1), Some(4), None, &[]);
assert_eq_slice(&input, Some(-1), Some(1), None, &[]);
}
#[test]
fn py_slice_step_forward() {
// indices: 0 1 2 3 4 5 6
let input = ['a', 'b', 'c', 'd', 'e', 'f', 'g'];
// Step size zero is invalid:
assert!(matches!(
input.py_slice(None, None, Some(0)),
Err(StepSizeZeroError)
));
assert!(matches!(
input.py_slice(Some(0), Some(5), Some(0)),
Err(StepSizeZeroError)
));
assert!(matches!(
input.py_slice(Some(0), Some(0), Some(0)),
Err(StepSizeZeroError)
));
assert_eq_slice(&input, Some(0), Some(8), Some(2), &['a', 'c', 'e', 'g']);
assert_eq_slice(&input, Some(0), Some(7), Some(2), &['a', 'c', 'e', 'g']);
assert_eq_slice(&input, Some(0), Some(6), Some(2), &['a', 'c', 'e']);
assert_eq_slice(&input, Some(0), Some(5), Some(2), &['a', 'c', 'e']);
assert_eq_slice(&input, Some(0), Some(4), Some(2), &['a', 'c']);
assert_eq_slice(&input, Some(0), Some(3), Some(2), &['a', 'c']);
assert_eq_slice(&input, Some(0), Some(2), Some(2), &['a']);
assert_eq_slice(&input, Some(0), Some(1), Some(2), &['a']);
assert_eq_slice(&input, Some(0), Some(0), Some(2), &[]);
assert_eq_slice(&input, Some(1), Some(5), Some(2), &['b', 'd']);
assert_eq_slice(&input, Some(0), Some(7), Some(3), &['a', 'd', 'g']);
assert_eq_slice(&input, Some(0), Some(6), Some(3), &['a', 'd']);
assert_eq_slice(&input, Some(0), None, Some(10), &['a']);
}
#[test]
fn py_slice_step_backward() {
// indices: 0 1 2 3 4 5 6
let input = ['a', 'b', 'c', 'd', 'e', 'f', 'g'];
assert_eq_slice(&input, Some(7), Some(0), Some(-2), &['g', 'e', 'c']);
assert_eq_slice(&input, Some(6), Some(0), Some(-2), &['g', 'e', 'c']);
assert_eq_slice(&input, Some(5), Some(0), Some(-2), &['f', 'd', 'b']);
assert_eq_slice(&input, Some(4), Some(0), Some(-2), &['e', 'c']);
assert_eq_slice(&input, Some(3), Some(0), Some(-2), &['d', 'b']);
assert_eq_slice(&input, Some(2), Some(0), Some(-2), &['c']);
assert_eq_slice(&input, Some(1), Some(0), Some(-2), &['b']);
assert_eq_slice(&input, Some(0), Some(0), Some(-2), &[]);
assert_eq_slice(&input, Some(7), None, Some(-2), &['g', 'e', 'c', 'a']);
assert_eq_slice(&input, None, None, Some(-2), &['g', 'e', 'c', 'a']);
assert_eq_slice(&input, None, Some(0), Some(-2), &['g', 'e', 'c']);
assert_eq_slice(&input, Some(5), Some(1), Some(-2), &['f', 'd']);
assert_eq_slice(&input, Some(5), Some(2), Some(-2), &['f', 'd']);
assert_eq_slice(&input, Some(5), Some(3), Some(-2), &['f']);
assert_eq_slice(&input, Some(5), Some(4), Some(-2), &['f']);
assert_eq_slice(&input, Some(5), Some(5), Some(-2), &[]);
assert_eq_slice(&input, Some(6), None, Some(-3), &['g', 'd', 'a']);
assert_eq_slice(&input, Some(6), Some(0), Some(-3), &['g', 'd']);
assert_eq_slice(&input, Some(7), None, Some(-10), &['g']);
assert_eq_slice(&input, Some(-6), Some(-9), Some(-1), &['b', 'a']);
assert_eq_slice(&input, Some(-6), Some(-8), Some(-1), &['b', 'a']);
assert_eq_slice(&input, Some(-6), Some(-7), Some(-1), &['b']);
assert_eq_slice(&input, Some(-6), Some(-6), Some(-1), &[]);
assert_eq_slice(&input, Some(-7), Some(-9), Some(-1), &['a']);
assert_eq_slice(&input, Some(-8), Some(-9), Some(-1), &[]);
assert_eq_slice(&input, Some(-9), Some(-9), Some(-1), &[]);
assert_eq_slice(&input, Some(-6), Some(-2), Some(-1), &[]);
assert_eq_slice(&input, Some(-9), Some(-6), Some(-1), &[]);
}
}