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//! An iterator over a slice.
//!
//! This iterator has both the length of the original slice, as
//! well as the current position of the iterator in the buffer.
#![cfg(all(feature = "parse", not(feature = "format")))]
use crate::iterator::BytesIter;
use core::{mem, ptr};
// AS DIGITS
// ---------
/// Trait to simplify creation of a `Bytes` object.
pub trait AsBytes<'a> {
/// Create `Bytes` from object.
fn bytes<const __: u128>(&'a self) -> Bytes<'a, __>;
}
impl<'a> AsBytes<'a> for [u8] {
#[inline]
fn bytes<const __: u128>(&'a self) -> Bytes<'a, __> {
Bytes::new(self)
}
}
// DIGITS
// ------
/// Slice iterator that stores the original length of the slice.
#[derive(Clone)]
pub struct Bytes<'a, const __: u128> {
/// The raw slice for the iterator.
slc: &'a [u8],
/// Current index of the iterator in the slice.
index: usize,
}
impl<'a, const __: u128> Bytes<'a, __> {
/// If each yielded value is adjacent in memory.
pub const IS_CONTIGUOUS: bool = true;
/// Create new byte object.
#[inline]
pub const fn new(slc: &'a [u8]) -> Self {
Self {
slc,
index: 0,
}
}
/// Get a ptr to the current start of the iterator.
#[inline]
pub fn as_ptr(&self) -> *const u8 {
self.as_slice().as_ptr()
}
/// Get a slice to the current start of the iterator.
#[inline]
pub fn as_slice(&self) -> &'a [u8] {
debug_assert!(self.index <= self.length());
// SAFETY: safe since index must be in range.
unsafe { self.slc.get_unchecked(self.index..) }
}
/// Get the total number of elements in the underlying slice.
#[inline]
pub fn length(&self) -> usize {
self.slc.len()
}
/// Get the current index of the iterator in the slice.
#[inline]
pub fn cursor(&self) -> usize {
self.index
}
/// Set the current index of the iterator in the slice.
///
/// # Safety
///
/// Safe if `index <= self.length()`.
#[inline]
pub unsafe fn set_cursor(&mut self, index: usize) {
debug_assert!(index <= self.length());
self.index = index
}
/// Get the current number of values returned by the iterator.
#[inline]
pub fn current_count(&self) -> usize {
self.index
}
/// Get if the buffer underlying the iterator is empty.
/// Same as `is_consumed`.
#[inline]
pub fn is_done(&self) -> bool {
self.index >= self.slc.len()
}
/// Read a value of a difference type from the iterator.
/// This advances the internal state of the iterator.
///
/// # Safety
///
/// Safe as long as the number of the buffer is contains as least as
/// many bytes as the size of V.
#[inline]
#[allow(clippy::assertions_on_constants)]
pub unsafe fn read_unchecked<V>(&self) -> V {
debug_assert!(Self::IS_CONTIGUOUS);
debug_assert!(self.as_slice().len() >= mem::size_of::<V>());
let slc = self.as_slice();
// SAFETY: safe as long as the slice has at least count elements.
unsafe { ptr::read_unaligned::<V>(slc.as_ptr() as *const _) }
}
/// Try to read a value of a different type from the iterator.
/// This advances the internal state of the iterator.
#[inline]
pub fn read<V>(&self) -> Option<V> {
if Self::IS_CONTIGUOUS && self.as_slice().len() >= mem::size_of::<V>() {
// SAFETY: safe since we've guaranteed the buffer is greater than
// the number of elements read.
unsafe { Some(self.read_unchecked()) }
} else {
None
}
}
/// Check if the next element is a given value.
#[inline]
pub fn first_is(&mut self, value: u8) -> bool {
if let Some(&c) = self.slc.get(self.index) {
c == value
} else {
false
}
}
/// Check if the next element is a given value without case sensitivity.
#[inline]
pub fn case_insensitive_first_is(&mut self, value: u8) -> bool {
if let Some(&c) = self.slc.get(self.index) {
c.to_ascii_lowercase() == value.to_ascii_lowercase()
} else {
false
}
}
/// Get iterator over integer digits.
#[inline]
pub fn integer_iter<'b>(&'b mut self) -> BytesIterator<'a, 'b, __> {
BytesIterator {
byte: self,
}
}
/// Get iterator over fraction digits.
#[inline]
pub fn fraction_iter<'b>(&'b mut self) -> BytesIterator<'a, 'b, __> {
BytesIterator {
byte: self,
}
}
/// Get iterator over exponent digits.
#[inline]
pub fn exponent_iter<'b>(&'b mut self) -> BytesIterator<'a, 'b, __> {
BytesIterator {
byte: self,
}
}
/// Get iterator over special floating point values.
#[inline]
pub fn special_iter<'b>(&'b mut self) -> BytesIterator<'a, 'b, __> {
BytesIterator {
byte: self,
}
}
/// Advance the byte by `N` elements.
///
/// # Safety
///
/// As long as the iterator is at least `N` elements, this
/// is safe.
#[inline]
#[allow(clippy::assertions_on_constants)]
pub unsafe fn step_by_unchecked(&mut self, count: usize) {
debug_assert!(Self::IS_CONTIGUOUS);
debug_assert!(self.as_slice().len() >= count);
self.index += count;
}
/// Advance the byte by 1 element.
///
/// # Safety
///
/// Safe as long as the iterator is not empty.
#[inline]
#[allow(clippy::assertions_on_constants)]
pub unsafe fn step_unchecked(&mut self) {
debug_assert!(Self::IS_CONTIGUOUS);
debug_assert!(!self.as_slice().is_empty());
self.index += 1;
}
}
// DIGITS ITERATOR
// ---------------
/// Slice iterator that stores the original length of the slice.
pub struct BytesIterator<'a: 'b, 'b, const __: u128> {
/// The internal byte object for the noskip iterator.
byte: &'b mut Bytes<'a, __>,
}
impl<'a: 'b, 'b, const __: u128> BytesIter<'a> for BytesIterator<'a, 'b, __> {
const IS_CONTIGUOUS: bool = Bytes::<'a, __>::IS_CONTIGUOUS;
#[inline]
fn as_ptr(&self) -> *const u8 {
self.byte.as_ptr()
}
#[inline]
fn as_slice(&self) -> &'a [u8] {
self.byte.as_slice()
}
#[inline]
fn length(&self) -> usize {
self.byte.length()
}
#[inline]
fn cursor(&self) -> usize {
self.byte.cursor()
}
#[inline]
unsafe fn set_cursor(&mut self, index: usize) {
debug_assert!(index <= self.length());
// SAFETY: safe if `index <= self.length()`.
unsafe { self.byte.set_cursor(index) };
}
#[inline]
fn current_count(&self) -> usize {
self.byte.current_count()
}
#[inline]
fn is_consumed(&mut self) -> bool {
Self::is_done(self)
}
#[inline]
fn is_done(&self) -> bool {
self.byte.is_done()
}
#[inline]
unsafe fn peek_unchecked(&mut self) -> <Self as Iterator>::Item {
// SAFETY: safe if `self.cursor() < self.length()`.
unsafe { self.byte.slc.get_unchecked(self.byte.index) }
}
#[inline]
fn peek(&mut self) -> Option<<Self as Iterator>::Item> {
if self.byte.index < self.byte.slc.len() {
// SAFETY: the slice cannot be empty, so this is safe
Some(unsafe { self.peek_unchecked() })
} else {
None
}
}
#[inline]
unsafe fn read_unchecked<V>(&self) -> V {
debug_assert!(self.as_slice().len() >= mem::size_of::<V>());
// SAFETY: safe as long as the slice has at least count elements.
unsafe { self.byte.read_unchecked() }
}
#[inline]
fn read<V>(&self) -> Option<V> {
self.byte.read()
}
#[inline]
unsafe fn step_by_unchecked(&mut self, count: usize) {
debug_assert!(self.as_slice().len() >= count);
// SAFETY: safe as long as `slc.len() >= count`.
unsafe { self.byte.step_by_unchecked(count) }
}
#[inline]
unsafe fn step_unchecked(&mut self) {
debug_assert!(!self.as_slice().is_empty());
// SAFETY: safe as long as `slc.len() >= 1`.
unsafe { self.byte.step_unchecked() }
}
}
impl<'a: 'b, 'b, const __: u128> Iterator for BytesIterator<'a, 'b, __> {
type Item = &'a u8;
#[inline]
fn next(&mut self) -> Option<Self::Item> {
let value = self.byte.slc.get(self.byte.index)?;
self.byte.index += 1;
Some(value)
}
}
impl<'a: 'b, 'b, const __: u128> ExactSizeIterator for BytesIterator<'a, 'b, __> {
#[inline]
fn len(&self) -> usize {
self.length() - self.cursor()
}
}