use std::{
iter::{DoubleEndedIterator, ExactSizeIterator, FusedIterator},
marker::PhantomData,
mem::size_of,
slice::from_raw_parts,
str::from_utf8,
};
use crate::Error;
#[cfg(target_endian = "little")]
use crate::endian_scalar::EndianScalar;
use crate::{endian_scalar::read_scalar_at, follow::Follow, primitives::*};
#[derive(Debug)]
pub struct Vector<'a, T: 'a>(&'a [u8], usize, PhantomData<T>);
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) -> Result<usize, Error> {
Ok(read_scalar_at::<UOffsetT>(&self.0, self.1)? as usize)
}
#[inline(always)]
pub fn is_empty(&self) -> Result<bool, Error> {
Ok(self.len()? == 0)
}
}
impl<'a, T: Follow<'a> + 'a> Vector<'a, T> {
#[inline(always)]
pub fn get(&self, idx: usize) -> Result<T::Inner, Error> {
debug_assert!(idx < read_scalar_at::<u32>(&self.0, self.1)? 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> {
let len = self.len().unwrap_or(0);
VectorIter::new(*self, len)
}
}
pub trait SafeSliceAccess {}
impl<'a, T: SafeSliceAccess + 'a> Vector<'a, T> {
pub fn safe_slice(self) -> Result<&'a [T], Error> {
let buf = self.0;
let loc = self.1;
let sz = size_of::<T>();
debug_assert!(sz > 0);
let len = read_scalar_at::<UOffsetT>(&buf, loc)? as usize;
let data_buf = buf
.get(loc + SIZE_UOFFSET..loc + SIZE_UOFFSET + len * sz)
.ok_or(Error::OutOfBounds)?;
let ptr = data_buf.as_ptr() as *const T;
let s: &'a [T] = unsafe { from_raw_parts(ptr, len) };
Ok(s)
}
}
impl SafeSliceAccess for u8 {}
impl SafeSliceAccess for i8 {}
#[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 unsafe fn follow_cast_ref<'a, T: Sized + 'a>(
buf: &'a [u8],
loc: usize,
) -> Result<&'a T, Error> {
let sz = size_of::<T>();
let buf = buf.get(loc..loc + sz).ok_or(Error::OutOfBounds)?;
let ptr = buf.as_ptr() as *const T;
Ok(&*ptr)
}
impl<'a> Follow<'a> for &'a str {
type Inner = &'a str;
fn follow(buf: &'a [u8], loc: usize) -> Result<Self::Inner, Error> {
let len = read_scalar_at::<UOffsetT>(&buf, loc)? as usize;
let end_loc = loc + SIZE_UOFFSET + len;
if end_loc >= buf.len() {
return Err(Error::OutOfBounds);
}
if buf[end_loc] != 0 {
return Err(Error::NonNullTerminatedString);
}
let slice = &buf[loc + SIZE_UOFFSET..end_loc];
from_utf8(slice).map_err(|_| Error::NonUtf8String)
}
}
#[cfg(target_endian = "little")]
fn follow_slice_helper<T>(buf: &[u8], loc: usize) -> Result<&[T], Error> {
let sz = size_of::<T>();
debug_assert!(sz > 0);
let len = read_scalar_at::<UOffsetT>(&buf, loc)? as usize;
let data_buf = buf
.get(loc + SIZE_UOFFSET..loc + SIZE_UOFFSET + len * sz)
.ok_or(Error::OutOfBounds)?;
let ptr = data_buf.as_ptr() as *const T;
let s: &[T] = unsafe { from_raw_parts(ptr, len) };
Ok(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) -> Result<Self::Inner, Error> {
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) -> Result<Self::Inner, Error> {
Ok(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 new(inner: Vector<'a, T>, len: usize) -> Self {
VectorIter {
buf: inner.0,
loc: inner.1 + SIZE_UOFFSET,
remaining: len,
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 = Result<T::Inner, Error>;
#[inline]
fn next(&mut self) -> Option<Self::Item> {
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<Self::Item> {
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<Self::Item> {
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<Self::Item> {
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 = Result<T::Inner, Error>;
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 = Result<T::Inner, Error>;
type IntoIter = VectorIter<'a, T>;
fn into_iter(self) -> Self::IntoIter {
self.iter()
}
}