use std::fmt::{Debug, Formatter, Result};
use std::iter::{DoubleEndedIterator, ExactSizeIterator, FusedIterator};
use std::marker::PhantomData;
use std::mem::size_of;
use std::slice::from_raw_parts;
use std::str::from_utf8_unchecked;
use crate::endian_scalar::read_scalar_at;
#[cfg(target_endian = "little")]
use crate::endian_scalar::EndianScalar;
use crate::follow::Follow;
use crate::primitives::*;
pub struct Vector<'a, T: 'a>(&'a [u8], usize, PhantomData<T>);
impl<'a, T: 'a> Default for Vector<'a, T> {
fn default() -> Self {
Self(
&[0; core::mem::size_of::<UOffsetT>()],
0,
Default::default(),
)
}
}
impl<'a, T> Debug for Vector<'a, T>
where
T: 'a + Follow<'a>,
<T as Follow<'a>>::Inner: Debug,
{
fn fmt(&self, f: &mut Formatter) -> Result {
f.debug_list().entries(self.iter()).finish()
}
}
impl<'a, T> Copy for Vector<'a, T> {}
impl<'a, T> Clone for Vector<'a, T> {
fn clone(&self) -> Self {
*self
}
}
impl<'a, T: 'a> Vector<'a, T> {
#[inline(always)]
pub fn new(buf: &'a [u8], loc: usize) -> Self {
Vector {
0: buf,
1: loc,
2: PhantomData,
}
}
#[inline(always)]
pub fn len(&self) -> usize {
unsafe { read_scalar_at::<UOffsetT>(&self.0, self.1) as usize }
}
#[inline(always)]
pub fn is_empty(&self) -> bool {
self.len() == 0
}
}
impl<'a, T: Follow<'a> + 'a> Vector<'a, T> {
#[inline(always)]
pub fn get(&self, idx: usize) -> T::Inner {
debug_assert!(idx < self.len() as usize);
let sz = size_of::<T>();
debug_assert!(sz > 0);
T::follow(self.0, self.1 as usize + SIZE_UOFFSET + sz * idx)
}
#[inline(always)]
pub fn iter(&self) -> VectorIter<'a, T> {
VectorIter::from_vector(*self)
}
}
pub trait SafeSliceAccess {}
impl<'a, T: SafeSliceAccess + 'a> Vector<'a, T> {
pub fn safe_slice(self) -> &'a [T] {
let buf = self.0;
let loc = self.1;
let sz = size_of::<T>();
debug_assert!(sz > 0);
let len = unsafe { read_scalar_at::<UOffsetT>(&buf, loc) } as usize;
let data_buf = &buf[loc + SIZE_UOFFSET..loc + SIZE_UOFFSET + len * sz];
let ptr = data_buf.as_ptr() as *const T;
let s: &'a [T] = unsafe { from_raw_parts(ptr, len) };
s
}
}
impl SafeSliceAccess for u8 {}
impl SafeSliceAccess for i8 {}
impl SafeSliceAccess for bool {}
#[cfg(target_endian = "little")]
mod le_safe_slice_impls {
impl super::SafeSliceAccess for u16 {}
impl super::SafeSliceAccess for u32 {}
impl super::SafeSliceAccess for u64 {}
impl super::SafeSliceAccess for i16 {}
impl super::SafeSliceAccess for i32 {}
impl super::SafeSliceAccess for i64 {}
impl super::SafeSliceAccess for f32 {}
impl super::SafeSliceAccess for f64 {}
}
#[cfg(target_endian = "little")]
pub use self::le_safe_slice_impls::*;
pub fn follow_cast_ref<'a, T: Sized + 'a>(buf: &'a [u8], loc: usize) -> &'a T {
let sz = size_of::<T>();
let buf = &buf[loc..loc + sz];
let ptr = buf.as_ptr() as *const T;
unsafe { &*ptr }
}
impl<'a> Follow<'a> for &'a str {
type Inner = &'a str;
fn follow(buf: &'a [u8], loc: usize) -> Self::Inner {
let len = unsafe { read_scalar_at::<UOffsetT>(&buf, loc) } as usize;
let slice = &buf[loc + SIZE_UOFFSET..loc + SIZE_UOFFSET + len];
unsafe { from_utf8_unchecked(slice) }
}
}
#[cfg(target_endian = "little")]
fn follow_slice_helper<T>(buf: &[u8], loc: usize) -> &[T] {
let sz = size_of::<T>();
debug_assert!(sz > 0);
let len = unsafe { read_scalar_at::<UOffsetT>(&buf, loc) as usize };
let data_buf = &buf[loc + SIZE_UOFFSET..loc + SIZE_UOFFSET + len * sz];
let ptr = data_buf.as_ptr() as *const T;
let s: &[T] = unsafe { from_raw_parts(ptr, len) };
s
}
#[cfg(target_endian = "little")]
impl<'a, T: EndianScalar> Follow<'a> for &'a [T] {
type Inner = &'a [T];
fn follow(buf: &'a [u8], loc: usize) -> Self::Inner {
follow_slice_helper::<T>(buf, loc)
}
}
impl<'a, T: Follow<'a> + 'a> Follow<'a> for Vector<'a, T> {
type Inner = Vector<'a, T>;
fn follow(buf: &'a [u8], loc: usize) -> Self::Inner {
Vector::new(buf, loc)
}
}
#[derive(Debug)]
pub struct VectorIter<'a, T: 'a> {
buf: &'a [u8],
loc: usize,
remaining: usize,
phantom: PhantomData<T>,
}
impl<'a, T: 'a> VectorIter<'a, T> {
#[inline]
pub fn from_vector(inner: Vector<'a, T>) -> Self {
VectorIter {
buf: inner.0,
loc: inner.1 + SIZE_UOFFSET,
remaining: inner.len(),
phantom: PhantomData,
}
}
#[inline]
pub fn from_slice(buf: &'a [u8], items_num: usize) -> Self {
VectorIter {
buf,
loc: 0,
remaining: items_num,
phantom: PhantomData,
}
}
}
impl<'a, T: Follow<'a> + 'a> Clone for VectorIter<'a, T> {
#[inline]
fn clone(&self) -> Self {
VectorIter {
buf: self.buf,
loc: self.loc,
remaining: self.remaining,
phantom: self.phantom,
}
}
}
impl<'a, T: Follow<'a> + 'a> Iterator for VectorIter<'a, T> {
type Item = T::Inner;
#[inline]
fn next(&mut self) -> Option<T::Inner> {
let sz = size_of::<T>();
debug_assert!(sz > 0);
if self.remaining == 0 {
None
} else {
let result = T::follow(self.buf, self.loc);
self.loc += sz;
self.remaining -= 1;
Some(result)
}
}
#[inline]
fn nth(&mut self, n: usize) -> Option<T::Inner> {
let sz = size_of::<T>();
debug_assert!(sz > 0);
self.remaining = self.remaining.saturating_sub(n);
self.loc = self.loc.wrapping_add(sz * n);
self.next()
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
(self.remaining, Some(self.remaining))
}
}
impl<'a, T: Follow<'a> + 'a> DoubleEndedIterator for VectorIter<'a, T> {
#[inline]
fn next_back(&mut self) -> Option<T::Inner> {
let sz = size_of::<T>();
debug_assert!(sz > 0);
if self.remaining == 0 {
None
} else {
self.remaining -= 1;
Some(T::follow(self.buf, self.loc + sz * self.remaining))
}
}
#[inline]
fn nth_back(&mut self, n: usize) -> Option<T::Inner> {
self.remaining = self.remaining.saturating_sub(n);
self.next_back()
}
}
impl<'a, T: 'a + Follow<'a>> ExactSizeIterator for VectorIter<'a, T> {
#[inline]
fn len(&self) -> usize {
self.remaining
}
}
impl<'a, T: 'a + Follow<'a>> FusedIterator for VectorIter<'a, T> {}
impl<'a, T: Follow<'a> + 'a> IntoIterator for Vector<'a, T> {
type Item = T::Inner;
type IntoIter = VectorIter<'a, T>;
#[inline]
fn into_iter(self) -> Self::IntoIter {
self.iter()
}
}
impl<'a, 'b, T: Follow<'a> + 'a> IntoIterator for &'b Vector<'a, T> {
type Item = T::Inner;
type IntoIter = VectorIter<'a, T>;
fn into_iter(self) -> Self::IntoIter {
self.iter()
}
}