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//! Specialized iterator traits.
//!
//! The traits are iterable, and provide optimizations for contiguous
//! iterators, while still working for non-contiguous data.
#![cfg(feature = "parse")]
// Re-export our digit iterators.
#[cfg(not(feature = "format"))]
pub use crate::noskip::{AsBytes, Bytes};
#[cfg(feature = "format")]
pub use crate::skip::{AsBytes, Bytes};
/// Iterator over a contiguous block of bytes.
///
/// This allows us to convert to-and-from-slices, raw pointers, and
/// peek/query the data from either end cheaply.
///
/// A default implementation is provided for slice iterators.
/// This trait **should never** return `null` from `as_ptr`, or be
/// implemented for non-contiguous data.
pub trait BytesIter<'a>: Iterator<Item = &'a u8> {
/// Determine if each yielded value is adjacent in memory.
const IS_CONTIGUOUS: bool;
/// Get a ptr to the current start of the iterator.
fn as_ptr(&self) -> *const u8;
/// Get a slice to the current start of the iterator.
fn as_slice(&self) -> &'a [u8];
/// Get the total number of elements in the underlying slice.
fn length(&self) -> usize;
/// Get the current index of the iterator in the slice.
fn cursor(&self) -> usize;
/// Set the current index of the iterator in the slice.
///
/// # Safety
///
/// Safe if `index <= self.length()`.
unsafe fn set_cursor(&mut self, index: usize);
/// Get the current number of values returned by the iterator.
fn current_count(&self) -> usize;
/// Get if the iterator cannot return any more elements.
///
/// This may advance the internal iterator state, but not
/// modify the next returned value.
fn is_consumed(&mut self) -> bool;
/// Get if the buffer underlying the iterator is empty.
///
/// This might not be the same thing as `is_consumed`: `is_consumed`
/// checks if any more elements may be returned, which may require
/// peeking the next value. Consumed merely checks if the
/// iterator has an empty slice. It is effectively a cheaper,
/// but weaker variant of `is_consumed()`.
fn is_done(&self) -> bool;
/// Determine if the iterator is contiguous.
#[inline]
fn is_contiguous(&self) -> bool {
Self::IS_CONTIGUOUS
}
/// Peek the next value of the iterator, without checking bounds.
///
/// # Safety
///
/// Safe as long as there is at least a single valid value left in
/// the iterator. Note that the behavior of this may lead to out-of-bounds
/// access (for contiguous iterators) or panics (for non-contiguous
/// iterators).
unsafe fn peek_unchecked(&mut self) -> Self::Item;
/// Peek the next value of the iterator, without consuming it.
fn peek(&mut self) -> Option<Self::Item>;
/// Check if the next element is a given value.
#[inline]
fn peek_is(&mut self, value: u8) -> bool {
if let Some(&c) = self.peek() {
c == value
} else {
false
}
}
/// Check if the next element is a given value without case sensitivity.
#[inline]
fn case_insensitive_peek_is(&mut self, value: u8) -> bool {
if let Some(&c) = self.peek() {
c.to_ascii_lowercase() == value.to_ascii_lowercase()
} else {
false
}
}
/// Skip zeros from the start of the iterator
#[inline]
fn skip_zeros(&mut self) -> usize {
let start = self.cursor();
while let Some(&b'0') = self.peek() {
self.next();
}
self.cursor() - start
}
/// 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.
unsafe fn read_unchecked<V>(&self) -> V;
/// Try to read a value of a different type from the iterator.
/// This advances the internal state of the iterator.
fn read<V>(&self) -> Option<V>;
/// Advance the internal slice by `N` elements.
///
/// # Safety
///
/// As long as the iterator is at least `N` elements, this
/// is safe.
unsafe fn step_by_unchecked(&mut self, count: usize);
/// Advance the internal slice by 1 element.
///
/// # Safety
///
/// Safe as long as the iterator is not empty.
#[inline]
unsafe fn step_unchecked(&mut self) {
unsafe { self.step_by_unchecked(1) };
}
}