77 lines
2.1 KiB
Rust
77 lines
2.1 KiB
Rust
use std::borrow::Cow;
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use std::convert::TryInto;
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use std::mem::size_of;
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use std::str;
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use heed::BoxedError;
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pub struct StrBEU32Codec;
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impl<'a> heed::BytesDecode<'a> for StrBEU32Codec {
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type DItem = (&'a str, u32);
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fn bytes_decode(bytes: &'a [u8]) -> Result<Self::DItem, BoxedError> {
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let footer_len = size_of::<u32>();
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if bytes.len() < footer_len {
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panic!() // TODO Do not panic
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}
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let (word, bytes) = bytes.split_at(bytes.len() - footer_len);
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let word = str::from_utf8(word)?;
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let pos = bytes.try_into().map(u32::from_be_bytes)?;
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Ok((word, pos))
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}
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}
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impl<'a> heed::BytesEncode<'a> for StrBEU32Codec {
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type EItem = (&'a str, u32);
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fn bytes_encode((word, pos): &Self::EItem) -> Result<Cow<[u8]>, BoxedError> {
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let pos = pos.to_be_bytes();
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let mut bytes = Vec::with_capacity(word.len() + pos.len());
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bytes.extend_from_slice(word.as_bytes());
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bytes.extend_from_slice(&pos[..]);
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Ok(Cow::Owned(bytes))
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}
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}
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pub struct StrBEU16Codec;
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impl<'a> heed::BytesDecode<'a> for StrBEU16Codec {
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type DItem = (&'a str, u16);
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fn bytes_decode(bytes: &'a [u8]) -> Result<Self::DItem, BoxedError> {
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let footer_len = size_of::<u16>();
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if bytes.len() < footer_len + 1 {
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panic!() // TODO do not panic
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}
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let (word_plus_nul_byte, bytes) = bytes.split_at(bytes.len() - footer_len);
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let (_, word) = word_plus_nul_byte.split_last().unwrap();
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let word = str::from_utf8(word).ok().unwrap();
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let pos = bytes.try_into().map(u16::from_be_bytes).ok().unwrap();
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Ok((word, pos))
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}
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}
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impl<'a> heed::BytesEncode<'a> for StrBEU16Codec {
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type EItem = (&'a str, u16);
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fn bytes_encode((word, pos): &Self::EItem) -> Result<Cow<[u8]>, BoxedError> {
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let pos = pos.to_be_bytes();
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let mut bytes = Vec::with_capacity(word.len() + 1 + pos.len());
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bytes.extend_from_slice(word.as_bytes());
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bytes.push(0);
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bytes.extend_from_slice(&pos[..]);
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Ok(Cow::Owned(bytes))
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}
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}
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