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use std::fs::File;
use std::io::{BufReader, Cursor, Read, Seek};
pub trait MmapBytesReader: Read + Seek + Send + Sync {
fn to_file(&self) -> Option<&File> {
None
}
fn to_bytes(&self) -> Option<&[u8]> {
None
}
}
impl MmapBytesReader for File {
fn to_file(&self) -> Option<&File> {
Some(self)
}
}
impl MmapBytesReader for BufReader<File> {
fn to_file(&self) -> Option<&File> {
Some(self.get_ref())
}
}
impl<T> MmapBytesReader for Cursor<T>
where
T: AsRef<[u8]> + Send + Sync,
{
fn to_bytes(&self) -> Option<&[u8]> {
Some(self.get_ref().as_ref())
}
}
impl<T: MmapBytesReader + ?Sized> MmapBytesReader for Box<T> {
fn to_file(&self) -> Option<&File> {
T::to_file(self)
}
fn to_bytes(&self) -> Option<&[u8]> {
T::to_bytes(self)
}
}
pub enum ReaderBytes<'a> {
Borrowed(&'a [u8]),
Owned(Vec<u8>),
Mapped(memmap::Mmap),
}
impl std::ops::Deref for ReaderBytes<'_> {
type Target = [u8];
fn deref(&self) -> &[u8] {
match self {
Self::Borrowed(ref_bytes) => ref_bytes,
Self::Owned(vec) => vec,
Self::Mapped(mmap) => mmap,
}
}
}
impl<'a, T: 'a + MmapBytesReader> From<&'a T> for ReaderBytes<'a> {
fn from(m: &'a T) -> Self {
match m.to_bytes() {
Some(s) => ReaderBytes::Borrowed(s),
None => {
let f = m.to_file().unwrap();
let mmap = unsafe { memmap::Mmap::map(f).unwrap() };
ReaderBytes::Mapped(mmap)
}
}
}
}