compression 0.1.5

Compression libraries implemented by pure Rust.
Documentation 
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//! rust-compression
//!
//! # Licensing
//! This Source Code is subject to the terms of the Mozilla Public License
//! version 2.0 (the "License"). You can obtain a copy of the License at
//! <http://mozilla.org/MPL/2.0/>.
//!
//! # Examples
//!
//! ```rust
//! use compression::prelude::*;
//! use std::cmp::Ordering;
//!
//! fn main() {
//!     pub fn comparison(lhs: LzssCode, rhs: LzssCode) -> Ordering {
//!         match (lhs, rhs) {
//!             (
//!                 LzssCode::Reference {
//!                     len: llen,
//!                     pos: lpos,
//!                 },
//!                 LzssCode::Reference {
//!                     len: rlen,
//!                     pos: rpos,
//!                 },
//!             ) => ((llen << 3) + rpos).cmp(&((rlen << 3) + lpos)).reverse(),
//!             (LzssCode::Symbol(_), LzssCode::Symbol(_)) => Ordering::Equal,
//!             (_, LzssCode::Symbol(_)) => Ordering::Greater,
//!             (LzssCode::Symbol(_), _) => Ordering::Less,
//!         }
//!     }
//!     # #[cfg(feature = "lzss")]
//!     let compressed = b"aabbaabbaabbaabb\n"
//!         .into_iter()
//!         .cloned()
//!         .encode(&mut LzssEncoder::new(comparison, 0x1_0000, 256, 3, 3), Action::Finish)
//!         .collect::<Result<Vec<_>, _>>()
//!         .unwrap();
//!
//!     # #[cfg(feature = "lzss")]
//!     let decompressed = compressed
//!         .iter()
//!         .cloned()
//!         .decode(&mut LzssDecoder::new(0x1_0000))
//!         .collect::<Result<Vec<_>, _>>()
//!         .unwrap();
//! }
//! ```
#![cfg(feature = "lzss")]

pub(crate) mod decoder;
pub(crate) mod encoder;
mod slidedict;

use crate::core::cmp::Ordering;

#[derive(Copy, Clone, Debug, PartialEq)]
pub enum LzssCode {
    Symbol(u8),
    Reference { len: usize, pos: usize },
}

impl Default for LzssCode {
    fn default() -> Self {
        LzssCode::Symbol(0)
    }
}

#[derive(Clone, Debug)]
pub(crate) struct MatchInfo {
    pub(crate) len: usize,
    pub(crate) pos: u16,
}

fn compare_match_info<F: Fn(LzssCode, LzssCode) -> Ordering>(
    comp: F,
    arg1: &MatchInfo,
    arg2: &MatchInfo,
) -> Ordering {
    comp(
        LzssCode::Reference {
            len: arg1.len,
            pos: arg1.pos as usize,
        },
        LzssCode::Reference {
            len: arg2.len,
            pos: arg2.pos as usize,
        },
    )
}

#[cfg(test)]
mod tests {
    use super::*;

    pub(crate) fn comparison(lhs: LzssCode, rhs: LzssCode) -> Ordering {
        match (lhs, rhs) {
            (
                LzssCode::Reference {
                    len: llen,
                    pos: lpos,
                },
                LzssCode::Reference {
                    len: rlen,
                    pos: rpos,
                },
            ) => ((llen << 3) + rpos).cmp(&((rlen << 3) + lpos)).reverse(),
            (LzssCode::Symbol(_), LzssCode::Symbol(_)) => Ordering::Equal,
            (_, LzssCode::Symbol(_)) => Ordering::Greater,
            (LzssCode::Symbol(_), _) => Ordering::Less,
        }
    }
}