29834581278

Committed 21 Jul 2026 01:28PM UTC coverage: 64.573%. Remained the same

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Cosmetic changes to LAW Rust development guidelines

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43.24

/src/dispatch/codes.rs

/*
 * SPDX-FileCopyrightText: 2025 Tommaso Fontana
 * SPDX-FileCopyrightText: 2025 Inria
 * SPDX-FileCopyrightText: 2025 Sebastiano Vigna
 *
 * SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
 */

//! Enumeration of all available codes, with associated read and write methods.
//!
//! This is the slower and more generic form of dispatching, mostly used for
//! testing and writing examples. For faster dispatching, consider using
//! [dynamic] or [static] dispatch.

use super::*;
#[cfg(feature = "serde")]
use alloc::string::{String, ToString};
#[cfg(feature = "mem_dbg")]
use mem_dbg::{MemDbg, MemSize};

/// An enum whose variants represent all the available codes.
///
/// This enum is kept in sync with implementations in the [`codes`] module.
///
/// Both [`Display`] and [`FromStr`] are implemented for this enum in a
/// compatible way, making it possible to store a code as a string in a
/// configuration file and then parse it back.
///
/// [`codes`]: crate::codes
/// [`Display`]: core::fmt::Display
/// [`FromStr`]: core::str::FromStr
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
#[cfg_attr(feature = "mem_dbg", derive(MemDbg, MemSize))]
#[cfg_attr(feature = "mem_dbg", mem_size(flat))]
#[cfg_attr(feature = "fuzz", derive(arbitrary::Arbitrary))]
#[non_exhaustive]
pub enum Codes {
    Unary,
    Gamma,
    Delta,
    Omega,
    VByteLe,
    VByteBe,
    Zeta(usize),
    Pi(usize),
    Golomb(u64),
    ExpGolomb(usize),
    Rice(usize),
}

impl Codes {
    /// Returns the canonical form of this code.
    ///
    /// Some codes are equivalent, in the sense that they are defined
    /// differently, but they give rise to the same codewords. Among equivalent
    /// codes, there is usually one that is faster to encode and decode, which
    /// we call the _canonical representative_ of the equivalence class.
    ///
    /// The mapping is:
    ///
    /// - [`Rice(0)`], [`Golomb(1)`] → [`Unary`]
    ///
    /// - [`Zeta(1)`], [`ExpGolomb(0)`], [`Pi(0)`] → [`Gamma`]
    ///
    /// - [`Golomb(2ⁿ)`] → [`Rice(n)`]
    ///
    /// [`Rice(0)`]: Codes::Rice
    /// [`Golomb(1)`]: Codes::Golomb
    /// [`Unary`]: Codes::Unary
    /// [`Zeta(1)`]: Codes::Zeta
    /// [`ExpGolomb(0)`]: Codes::ExpGolomb
    /// [`Pi(0)`]: Codes::Pi
    /// [`Gamma`]: Codes::Gamma
    /// [`Golomb(2ⁿ)`]: Codes::Golomb
    /// [`Rice(n)`]: Codes::Rice
    #[must_use]
    pub const fn canonicalize(self) -> Self {
        match self {
            Self::Zeta(1) | Self::ExpGolomb(0) | Self::Pi(0) => Self::Gamma,
            Self::Rice(0) | Self::Golomb(1) => Self::Unary,
            Self::Golomb(b) if b.is_power_of_two() => Self::Rice(b.trailing_zeros() as usize),
            other => other,
        }
    }

    /// Delegates to the [`DynamicCodeRead`] implementation.
    ///
    /// This inherent method is provided to reduce ambiguity in method
    /// resolution.
    #[inline(always)]
    pub fn read<E: Endianness, CR: CodesRead<E> + ?Sized>(
        &self,
        reader: &mut CR,
    ) -> Result<u64, CR::Error> {
        DynamicCodeRead::read(self, reader)
    }

    /// Delegates to the [`DynamicCodeWrite`] implementation.
    ///
    /// This inherent method is provided to reduce ambiguity in method
    /// resolution.
    #[inline(always)]
    pub fn write<E: Endianness, CW: CodesWrite<E> + ?Sized>(
        &self,
        writer: &mut CW,
        n: u64,
    ) -> Result<usize, CW::Error> {
        DynamicCodeWrite::write(self, writer, n)
    }

    /// Converts a code to the constants in the [`code_consts`] module used for
    /// [`ConstCode`]. This is mostly used to verify that the code is supported
    /// by [`ConstCode`].
    ///
    /// The code is [canonicalized] before the conversion, so equivalent codes
    /// map to the same constant.
    ///
    /// # Errors
    ///
    /// Returns [`DispatchError::UnsupportedCode`] if the (canonicalized)
    /// code has no corresponding constant in [`code_consts`].
    ///
    /// [canonicalized]: Codes::canonicalize
    pub const fn to_code_const(&self) -> Result<usize, DispatchError> {
        Ok(match self.canonicalize() {
            Self::Unary => code_consts::UNARY,
            Self::Gamma => code_consts::GAMMA,
            Self::Delta => code_consts::DELTA,
            Self::Omega => code_consts::OMEGA,
            Self::VByteLe => code_consts::VBYTE_LE,
            Self::VByteBe => code_consts::VBYTE_BE,
            Self::Zeta(2) => code_consts::ZETA2,
            Self::Zeta(3) => code_consts::ZETA3,
            Self::Zeta(4) => code_consts::ZETA4,
            Self::Zeta(5) => code_consts::ZETA5,
            Self::Zeta(6) => code_consts::ZETA6,
            Self::Zeta(7) => code_consts::ZETA7,
            Self::Zeta(8) => code_consts::ZETA8,
            Self::Zeta(9) => code_consts::ZETA9,
            Self::Zeta(10) => code_consts::ZETA10,
            Self::Rice(1) => code_consts::RICE1,
            Self::Rice(2) => code_consts::RICE2,
            Self::Rice(3) => code_consts::RICE3,
            Self::Rice(4) => code_consts::RICE4,
            Self::Rice(5) => code_consts::RICE5,
            Self::Rice(6) => code_consts::RICE6,
            Self::Rice(7) => code_consts::RICE7,
            Self::Rice(8) => code_consts::RICE8,
            Self::Rice(9) => code_consts::RICE9,
            Self::Rice(10) => code_consts::RICE10,
            Self::Pi(1) => code_consts::PI1,
            Self::Pi(2) => code_consts::PI2,
            Self::Pi(3) => code_consts::PI3,
            Self::Pi(4) => code_consts::PI4,
            Self::Pi(5) => code_consts::PI5,
            Self::Pi(6) => code_consts::PI6,
            Self::Pi(7) => code_consts::PI7,
            Self::Pi(8) => code_consts::PI8,
            Self::Pi(9) => code_consts::PI9,
            Self::Pi(10) => code_consts::PI10,
            Self::Golomb(3) => code_consts::GOLOMB3,
            Self::Golomb(5) => code_consts::GOLOMB5,
            Self::Golomb(6) => code_consts::GOLOMB6,
            Self::Golomb(7) => code_consts::GOLOMB7,
            Self::Golomb(9) => code_consts::GOLOMB9,
            Self::Golomb(10) => code_consts::GOLOMB10,
            Self::ExpGolomb(1) => code_consts::EXP_GOLOMB1,
            Self::ExpGolomb(2) => code_consts::EXP_GOLOMB2,
            Self::ExpGolomb(3) => code_consts::EXP_GOLOMB3,
            Self::ExpGolomb(4) => code_consts::EXP_GOLOMB4,
            Self::ExpGolomb(5) => code_consts::EXP_GOLOMB5,
            Self::ExpGolomb(6) => code_consts::EXP_GOLOMB6,
            Self::ExpGolomb(7) => code_consts::EXP_GOLOMB7,
            Self::ExpGolomb(8) => code_consts::EXP_GOLOMB8,
            Self::ExpGolomb(9) => code_consts::EXP_GOLOMB9,
            Self::ExpGolomb(10) => code_consts::EXP_GOLOMB10,
            _ => {
                return Err(DispatchError::UnsupportedCode(*self));
            }
        })
    }

    /// Converts a value from [`code_consts`] to a code.
    ///
    /// # Errors
    ///
    /// Returns [`DispatchError::UnsupportedCodeConst`] if the value
    /// does not correspond to any known code constant.
    pub const fn from_code_const(const_code: usize) -> Result<Self, DispatchError> {
        Ok(match const_code {
            code_consts::UNARY => Self::Unary,
            code_consts::GAMMA => Self::Gamma,
            code_consts::DELTA => Self::Delta,
            code_consts::OMEGA => Self::Omega,
            code_consts::VBYTE_LE => Self::VByteLe,
            code_consts::VBYTE_BE => Self::VByteBe,
            code_consts::ZETA2 => Self::Zeta(2),
            code_consts::ZETA3 => Self::Zeta(3),
            code_consts::ZETA4 => Self::Zeta(4),
            code_consts::ZETA5 => Self::Zeta(5),
            code_consts::ZETA6 => Self::Zeta(6),
            code_consts::ZETA7 => Self::Zeta(7),
            code_consts::ZETA8 => Self::Zeta(8),
            code_consts::ZETA9 => Self::Zeta(9),
            code_consts::ZETA10 => Self::Zeta(10),
            code_consts::RICE1 => Self::Rice(1),
            code_consts::RICE2 => Self::Rice(2),
            code_consts::RICE3 => Self::Rice(3),
            code_consts::RICE4 => Self::Rice(4),
            code_consts::RICE5 => Self::Rice(5),
            code_consts::RICE6 => Self::Rice(6),
            code_consts::RICE7 => Self::Rice(7),
            code_consts::RICE8 => Self::Rice(8),
            code_consts::RICE9 => Self::Rice(9),
            code_consts::RICE10 => Self::Rice(10),
            code_consts::PI1 => Self::Pi(1),
            code_consts::PI2 => Self::Pi(2),
            code_consts::PI3 => Self::Pi(3),
            code_consts::PI4 => Self::Pi(4),
            code_consts::PI5 => Self::Pi(5),
            code_consts::PI6 => Self::Pi(6),
            code_consts::PI7 => Self::Pi(7),
            code_consts::PI8 => Self::Pi(8),
            code_consts::PI9 => Self::Pi(9),
            code_consts::PI10 => Self::Pi(10),
            code_consts::GOLOMB3 => Self::Golomb(3),
            code_consts::GOLOMB5 => Self::Golomb(5),
            code_consts::GOLOMB6 => Self::Golomb(6),
            code_consts::GOLOMB7 => Self::Golomb(7),
            code_consts::GOLOMB9 => Self::Golomb(9),
            code_consts::GOLOMB10 => Self::Golomb(10),
            code_consts::EXP_GOLOMB1 => Self::ExpGolomb(1),
            code_consts::EXP_GOLOMB2 => Self::ExpGolomb(2),
            code_consts::EXP_GOLOMB3 => Self::ExpGolomb(3),
            code_consts::EXP_GOLOMB4 => Self::ExpGolomb(4),
            code_consts::EXP_GOLOMB5 => Self::ExpGolomb(5),
            code_consts::EXP_GOLOMB6 => Self::ExpGolomb(6),
            code_consts::EXP_GOLOMB7 => Self::ExpGolomb(7),
            code_consts::EXP_GOLOMB8 => Self::ExpGolomb(8),
            code_consts::EXP_GOLOMB9 => Self::ExpGolomb(9),
            code_consts::EXP_GOLOMB10 => Self::ExpGolomb(10),
            _ => return Err(DispatchError::UnsupportedCodeConst(const_code)),
        })
    }
}

impl DynamicCodeRead for Codes {
    #[inline]
    fn read<E: Endianness, CR: CodesRead<E> + ?Sized>(
        &self,
        reader: &mut CR,
    ) -> Result<u64, CR::Error> {
        Ok(match self.canonicalize() {
            Codes::Unary => reader.read_unary()?,
            Codes::Gamma => reader.read_gamma()?,
            Codes::Delta => reader.read_delta()?,
            Codes::Omega => reader.read_omega()?,
            Codes::VByteBe => reader.read_vbyte_be()?,
            Codes::VByteLe => reader.read_vbyte_le()?,
            Codes::Zeta(3) => reader.read_zeta3()?,
            Codes::Zeta(k) => reader.read_zeta(k)?,
            Codes::Pi(2) => reader.read_pi2()?,
            Codes::Pi(k) => reader.read_pi(k)?,
            Codes::Golomb(b) => reader.read_golomb(b)?,
            Codes::ExpGolomb(k) => reader.read_exp_golomb(k)?,
            Codes::Rice(log2_b) => reader.read_rice(log2_b)?,
        })
    }
}

impl DynamicCodeWrite for Codes {
    #[inline]
    fn write<E: Endianness, CW: CodesWrite<E> + ?Sized>(
        &self,
        writer: &mut CW,
        n: u64,
    ) -> Result<usize, CW::Error> {
        Ok(match self.canonicalize() {
            Codes::Unary => writer.write_unary(n)?,
            Codes::Gamma => writer.write_gamma(n)?,
            Codes::Delta => writer.write_delta(n)?,
            Codes::Omega => writer.write_omega(n)?,
            Codes::VByteBe => writer.write_vbyte_be(n)?,
            Codes::VByteLe => writer.write_vbyte_le(n)?,
            Codes::Zeta(3) => writer.write_zeta3(n)?,
            Codes::Zeta(k) => writer.write_zeta(n, k)?,
            Codes::Pi(2) => writer.write_pi2(n)?,
            Codes::Pi(k) => writer.write_pi(n, k)?,
            Codes::Golomb(b) => writer.write_golomb(n, b)?,
            Codes::ExpGolomb(k) => writer.write_exp_golomb(n, k)?,
            Codes::Rice(log2_b) => writer.write_rice(n, log2_b)?,
        })
    }
}

impl<E: Endianness, CR: CodesRead<E> + ?Sized> StaticCodeRead<E, CR> for Codes {
    #[inline(always)]
    fn read(&self, reader: &mut CR) -> Result<u64, CR::Error> {
        <Self as DynamicCodeRead>::read(self, reader)
    }
}

impl<E: Endianness, CW: CodesWrite<E> + ?Sized> StaticCodeWrite<E, CW> for Codes {
    #[inline(always)]
    fn write(&self, writer: &mut CW, n: u64) -> Result<usize, CW::Error> {
        <Self as DynamicCodeWrite>::write(self, writer, n)
    }
}

impl CodeLen for Codes {
    #[inline]
    fn len(&self, n: u64) -> usize {
        match self.canonicalize() {
            // The checked conversion avoids truncation on 32-bit platforms
            Codes::Unary => n
                .checked_add(1)
                .and_then(|len| usize::try_from(len).ok())
                .expect("unary code length does not fit in a usize"),
            Codes::Gamma => len_gamma(n),
            Codes::Delta => len_delta(n),
            Codes::Omega => len_omega(n),
            Codes::VByteLe | Codes::VByteBe => bit_len_vbyte(n),
            Codes::Zeta(k) => len_zeta(n, k),
            Codes::Pi(k) => len_pi(n, k),
            Codes::Golomb(b) => len_golomb(n, b),
            Codes::ExpGolomb(k) => len_exp_golomb(n, k),
            Codes::Rice(log2_b) => len_rice(n, log2_b),
        }
    }
}

#[cfg(feature = "serde")]
impl serde::Serialize for Codes {
    fn serialize<S: serde::Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
        serializer.serialize_str(&self.to_string())
    }
}

#[cfg(feature = "serde")]
impl<'de> serde::Deserialize<'de> for Codes {
    fn deserialize<D: serde::Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
        let s = String::deserialize(deserializer)?;
        s.parse().map_err(serde::de::Error::custom)
    }
}

impl core::fmt::Display for Codes {
    fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
        match self {
            Codes::Unary => write!(f, "Unary"),
            Codes::Gamma => write!(f, "Gamma"),
            Codes::Delta => write!(f, "Delta"),
            Codes::Omega => write!(f, "Omega"),
            Codes::VByteBe => write!(f, "VByteBe"),
            Codes::VByteLe => write!(f, "VByteLe"),
            Codes::Zeta(k) => write!(f, "Zeta({})", k),
            Codes::Pi(k) => write!(f, "Pi({})", k),
            Codes::Golomb(b) => write!(f, "Golomb({})", b),
            Codes::ExpGolomb(k) => write!(f, "ExpGolomb({})", k),
            Codes::Rice(log2_b) => write!(f, "Rice({})", log2_b),
        }
    }
}

fn array_format_error(s: &str) -> [u8; 32] {
    let mut error_buffer = [0u8; 32];
    let len = s.len().min(32);
    error_buffer[..len].copy_from_slice(&s.as_bytes()[..len]);
    error_buffer
}

impl core::str::FromStr for Codes {
    type Err = CodeError;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match s {
            "Unary" => Ok(Codes::Unary),
            "Gamma" => Ok(Codes::Gamma),
            "Delta" => Ok(Codes::Delta),
            "Omega" => Ok(Codes::Omega),
            "VByteBe" => Ok(Codes::VByteBe),
            "VByteLe" => Ok(Codes::VByteLe),

            _ => {
                // Strict grammar: exactly `Name(param)` with `param` a single
                // integer and nothing after the closing parenthesis. The former
                // `split` accepted trailing/incomplete text (e.g. `Zeta(3)x`).
                let inner = s
                    .strip_suffix(')')
                    .ok_or_else(|| CodeError::UnknownCode(array_format_error(s)))?;
                let (name, param) = inner
                    .split_once('(')
                    .ok_or_else(|| CodeError::UnknownCode(array_format_error(s)))?;
                if param.contains('(') || param.contains(')') {
                    return Err(CodeError::UnknownCode(array_format_error(s)));
                }
                let invalid = || CodeError::InvalidParameter(array_format_error(s));
                match name {
                    // zeta is defined for k in [1..64).
                    "Zeta" => {
                        let k: usize = param.parse()?;
                        if k == 0 || k >= 64 {
                            return Err(invalid());
                        }
                        Ok(Codes::Zeta(k))
                    }
                    // pi, exponential Golomb and Rice shift by their parameter,
                    // so it must stay below 64.
                    "Pi" => {
                        let k: usize = param.parse()?;
                        if k >= 64 {
                            return Err(invalid());
                        }
                        Ok(Codes::Pi(k))
                    }
                    "ExpGolomb" => {
                        let k: usize = param.parse()?;
                        if k >= 64 {
                            return Err(invalid());
                        }
                        Ok(Codes::ExpGolomb(k))
                    }
                    "Rice" => {
                        let k: usize = param.parse()?;
                        if k >= 64 {
                            return Err(invalid());
                        }
                        Ok(Codes::Rice(k))
                    }
                    // Golomb divides by its modulus, which must be positive.
                    "Golomb" => {
                        let b: u64 = param.parse()?;
                        if b == 0 {
                            return Err(invalid());
                        }
                        Ok(Codes::Golomb(b))
                    }
                    _ => Err(CodeError::UnknownCode(array_format_error(name))),
                }
            }
        }
    }
}

/// Error type for parsing a code from a string.
#[derive(Debug, Clone)]
pub enum CodeError {
    /// Error parsing an integer parameter.
    ParseError(core::num::ParseIntError),
    /// Unknown code name. Uses a fixed-size array instead of `String` for `no_std` compatibility.
    UnknownCode([u8; 32]),
    /// A parameter is outside the valid range for its code (for example
    /// `Golomb(0)`, `Zeta(0)`, or a shift parameter `>= 64`).
    InvalidParameter([u8; 32]),
}
impl core::error::Error for CodeError {}
impl core::fmt::Display for CodeError {
    fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
        match self {
            CodeError::ParseError(e) => write!(f, "parse error: {}", e),
            CodeError::UnknownCode(s) => {
                write!(f, "unknown code: ")?;
                for c in s {
                    if *c == 0 {
                        break;
                    }
                    write!(f, "{}", *c as char)?;
                }
                Ok(())
            }
            CodeError::InvalidParameter(s) => {
                write!(f, "invalid parameter for code: ")?;
                for c in s {
                    if *c == 0 {
                        break;
                    }
                    write!(f, "{}", *c as char)?;
                }
                Ok(())
            }
        }
    }
}

impl From<core::num::ParseIntError> for CodeError {
    fn from(e: core::num::ParseIntError) -> Self {
        CodeError::ParseError(e)
    }
}

/// Structure representing minimal binary coding with a fixed upper bound.
///
/// [Minimal binary coding] does not fit the [`Codes`] enum because it is not
/// defined for all integers.
///
/// Instances of this structure can be used in contexts in which a
/// [`DynamicCodeRead`], [`DynamicCodeWrite`], [`StaticCodeRead`],
/// [`StaticCodeWrite`] or [`CodeLen`] implementing minimal binary coding
/// is necessary.
///
/// [Minimal binary coding]: crate::codes::minimal_binary
#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
pub struct MinimalBinary(
    /// The upper bound of the minimal binary code.
    pub u64,
);

impl DynamicCodeRead for MinimalBinary {
    fn read<E: Endianness, R: CodesRead<E> + ?Sized>(
        &self,
        reader: &mut R,
    ) -> Result<u64, R::Error> {
        reader.read_minimal_binary(self.0)
    }
}

impl DynamicCodeWrite for MinimalBinary {
    fn write<E: Endianness, W: CodesWrite<E> + ?Sized>(
        &self,
        writer: &mut W,
        n: u64,
    ) -> Result<usize, W::Error> {
        writer.write_minimal_binary(n, self.0)
    }
}

impl<E: Endianness, CR: CodesRead<E> + ?Sized> StaticCodeRead<E, CR> for MinimalBinary {
    fn read(&self, reader: &mut CR) -> Result<u64, CR::Error> {
        <Self as DynamicCodeRead>::read(self, reader)
    }
}

impl<E: Endianness, CW: CodesWrite<E> + ?Sized> StaticCodeWrite<E, CW> for MinimalBinary {
    fn write(&self, writer: &mut CW, n: u64) -> Result<usize, CW::Error> {
        <Self as DynamicCodeWrite>::write(self, writer, n)
    }
}

impl CodeLen for MinimalBinary {
    fn len(&self, n: u64) -> usize {
        len_minimal_binary(n, self.0)
    }
}

#[cfg(test)]
mod parse_tests {
    use super::Codes;
    use core::str::FromStr;

    #[test]
    fn test_parses_valid_parameterized_codes() {
        assert_eq!(Codes::from_str("Unary").unwrap(), Codes::Unary);
        assert_eq!(Codes::from_str("Zeta(3)").unwrap(), Codes::Zeta(3));
        assert_eq!(Codes::from_str("Pi(2)").unwrap(), Codes::Pi(2));
        assert_eq!(Codes::from_str("Golomb(7)").unwrap(), Codes::Golomb(7));
        assert_eq!(
            Codes::from_str("ExpGolomb(0)").unwrap(),
            Codes::ExpGolomb(0)
        );
        assert_eq!(Codes::from_str("Rice(0)").unwrap(), Codes::Rice(0));
        assert_eq!(Codes::from_str("Rice(63)").unwrap(), Codes::Rice(63));
    }

    #[test]
    fn test_rejects_out_of_range_parameters() {
        // These previously deserialized into values that panic on first use
        // (divide-by-zero) or shift by >= 64.
        assert!(Codes::from_str("Golomb(0)").is_err());
        assert!(Codes::from_str("Zeta(0)").is_err());
        assert!(Codes::from_str("Zeta(64)").is_err());
        assert!(Codes::from_str("Rice(64)").is_err());
        assert!(Codes::from_str("Pi(64)").is_err());
        assert!(Codes::from_str("ExpGolomb(64)").is_err());
    }

    #[test]
    fn test_rejects_malformed_grammar() {
        assert!(Codes::from_str("Zeta(3").is_err());
        assert!(Codes::from_str("Zeta(3)x").is_err());
        assert!(Codes::from_str("Zeta(3)(4)").is_err());
        assert!(Codes::from_str("Zeta()").is_err());
        assert!(Codes::from_str("Nope(1)").is_err());
    }
}

1	/*
2	* SPDX-FileCopyrightText: 2025 Tommaso Fontana
3	* SPDX-FileCopyrightText: 2025 Inria
4	* SPDX-FileCopyrightText: 2025 Sebastiano Vigna
5	*
6	* SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
7	*/
8
9	//! Enumeration of all available codes, with associated read and write methods.
10	//!
11	//! This is the slower and more generic form of dispatching, mostly used for
12	//! testing and writing examples. For faster dispatching, consider using
13	//! [dynamic] or [static] dispatch.
14
15	use super::*;
16	#[cfg(feature = "serde")]
17	use alloc::string::{String, ToString};
18	#[cfg(feature = "mem_dbg")]
19	use mem_dbg::{MemDbg, MemSize};
20
21	/// An enum whose variants represent all the available codes.
22	///
23	/// This enum is kept in sync with implementations in the [`codes`] module.
24	///
25	/// Both [`Display`] and [`FromStr`] are implemented for this enum in a
26	/// compatible way, making it possible to store a code as a string in a
27	/// configuration file and then parse it back.
28	///
29	/// [`codes`]: crate::codes
30	/// [`Display`]: core::fmt::Display
31	/// [`FromStr`]: core::str::FromStr
32	#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
33	#[cfg_attr(feature = "mem_dbg", derive(MemDbg, MemSize))]
34	#[cfg_attr(feature = "mem_dbg", mem_size(flat))]
35	#[cfg_attr(feature = "fuzz", derive(arbitrary::Arbitrary))]
36	#[non_exhaustive]
37	pub enum Codes {
38	Unary,
39	Gamma,
40	Delta,
41	Omega,
42	VByteLe,
43	VByteBe,
44	Zeta(usize),
45	Pi(usize),
46	Golomb(u64),
47	ExpGolomb(usize),
48	Rice(usize),
49	}
50
51	impl Codes {
52	/// Returns the canonical form of this code.
53	///
54	/// Some codes are equivalent, in the sense that they are defined
55	/// differently, but they give rise to the same codewords. Among equivalent
56	/// codes, there is usually one that is faster to encode and decode, which
57	/// we call the _canonical representative_ of the equivalence class.
58	///
59	/// The mapping is:
60	///
61	/// - [`Rice(0)`], [`Golomb(1)`] → [`Unary`]
62	///
63	/// - [`Zeta(1)`], [`ExpGolomb(0)`], [`Pi(0)`] → [`Gamma`]
64	///
65	/// - [`Golomb(2ⁿ)`] → [`Rice(n)`]
66	///
67	/// [`Rice(0)`]: Codes::Rice
68	/// [`Golomb(1)`]: Codes::Golomb
69	/// [`Unary`]: Codes::Unary
70	/// [`Zeta(1)`]: Codes::Zeta
71	/// [`ExpGolomb(0)`]: Codes::ExpGolomb
72	/// [`Pi(0)`]: Codes::Pi
73	/// [`Gamma`]: Codes::Gamma
74	/// [`Golomb(2ⁿ)`]: Codes::Golomb
75	/// [`Rice(n)`]: Codes::Rice
76	#[must_use]
77	pub const fn canonicalize(self) -> Self {	691,248✔
78	match self {	98,436✔
79	Self::Zeta(1) \| Self::ExpGolomb(0) \| Self::Pi(0) => Self::Gamma,	39,348✔
80	Self::Rice(0) \| Self::Golomb(1) => Self::Unary,	24,672✔
81	Self::Golomb(b) if b.is_power_of_two() => Self::Rice(b.trailing_zeros() as usize),	307,464✔
82	other => other,	1,180,728✔
83	}
84	}
85
86	/// Delegates to the [`DynamicCodeRead`] implementation.
87	///
88	/// This inherent method is provided to reduce ambiguity in method
89	/// resolution.
90	#[inline(always)]
91	pub fn read<E: Endianness, CR: CodesRead<E> + ?Sized>(	×
92	&self,
93	reader: &mut CR,
94	) -> Result<u64, CR::Error> {
95	DynamicCodeRead::read(self, reader)	×
96	}
97
98	/// Delegates to the [`DynamicCodeWrite`] implementation.
99	///
100	/// This inherent method is provided to reduce ambiguity in method
101	/// resolution.
102	#[inline(always)]
103	pub fn write<E: Endianness, CW: CodesWrite<E> + ?Sized>(	×
104	&self,
105	writer: &mut CW,
106	n: u64,
107	) -> Result<usize, CW::Error> {
108	DynamicCodeWrite::write(self, writer, n)	×
109	}
110
111	/// Converts a code to the constants in the [`code_consts`] module used for
112	/// [`ConstCode`]. This is mostly used to verify that the code is supported
113	/// by [`ConstCode`].
114	///
115	/// The code is [canonicalized] before the conversion, so equivalent codes
116	/// map to the same constant.
117	///
118	/// # Errors
119	///
120	/// Returns [`DispatchError::UnsupportedCode`] if the (canonicalized)
121	/// code has no corresponding constant in [`code_consts`].
122	///
123	/// [canonicalized]: Codes::canonicalize
124	pub const fn to_code_const(&self) -> Result<usize, DispatchError> {	×
125	Ok(match self.canonicalize() {	×
126	Self::Unary => code_consts::UNARY,	×
127	Self::Gamma => code_consts::GAMMA,	×
128	Self::Delta => code_consts::DELTA,	×
129	Self::Omega => code_consts::OMEGA,	×
130	Self::VByteLe => code_consts::VBYTE_LE,	×
131	Self::VByteBe => code_consts::VBYTE_BE,	×
132	Self::Zeta(2) => code_consts::ZETA2,	×
133	Self::Zeta(3) => code_consts::ZETA3,	×
134	Self::Zeta(4) => code_consts::ZETA4,	×
135	Self::Zeta(5) => code_consts::ZETA5,	×
136	Self::Zeta(6) => code_consts::ZETA6,	×
137	Self::Zeta(7) => code_consts::ZETA7,	×
138	Self::Zeta(8) => code_consts::ZETA8,	×
139	Self::Zeta(9) => code_consts::ZETA9,	×
140	Self::Zeta(10) => code_consts::ZETA10,	×
141	Self::Rice(1) => code_consts::RICE1,	×
142	Self::Rice(2) => code_consts::RICE2,	×
143	Self::Rice(3) => code_consts::RICE3,	×
144	Self::Rice(4) => code_consts::RICE4,	×
145	Self::Rice(5) => code_consts::RICE5,	×
146	Self::Rice(6) => code_consts::RICE6,	×
147	Self::Rice(7) => code_consts::RICE7,	×
148	Self::Rice(8) => code_consts::RICE8,	×
149	Self::Rice(9) => code_consts::RICE9,	×
150	Self::Rice(10) => code_consts::RICE10,	×
151	Self::Pi(1) => code_consts::PI1,	×
152	Self::Pi(2) => code_consts::PI2,	×
153	Self::Pi(3) => code_consts::PI3,	×
154	Self::Pi(4) => code_consts::PI4,	×
155	Self::Pi(5) => code_consts::PI5,	×
156	Self::Pi(6) => code_consts::PI6,	×
157	Self::Pi(7) => code_consts::PI7,	×
158	Self::Pi(8) => code_consts::PI8,	×
159	Self::Pi(9) => code_consts::PI9,	×
160	Self::Pi(10) => code_consts::PI10,	×
161	Self::Golomb(3) => code_consts::GOLOMB3,	×
162	Self::Golomb(5) => code_consts::GOLOMB5,	×
163	Self::Golomb(6) => code_consts::GOLOMB6,	×
164	Self::Golomb(7) => code_consts::GOLOMB7,	×
165	Self::Golomb(9) => code_consts::GOLOMB9,	×
166	Self::Golomb(10) => code_consts::GOLOMB10,	×
167	Self::ExpGolomb(1) => code_consts::EXP_GOLOMB1,	×
168	Self::ExpGolomb(2) => code_consts::EXP_GOLOMB2,	×
169	Self::ExpGolomb(3) => code_consts::EXP_GOLOMB3,	×
170	Self::ExpGolomb(4) => code_consts::EXP_GOLOMB4,	×
171	Self::ExpGolomb(5) => code_consts::EXP_GOLOMB5,	×
172	Self::ExpGolomb(6) => code_consts::EXP_GOLOMB6,	×
173	Self::ExpGolomb(7) => code_consts::EXP_GOLOMB7,	×
174	Self::ExpGolomb(8) => code_consts::EXP_GOLOMB8,	×
175	Self::ExpGolomb(9) => code_consts::EXP_GOLOMB9,	×
176	Self::ExpGolomb(10) => code_consts::EXP_GOLOMB10,	×
177	_ => {
178	return Err(DispatchError::UnsupportedCode(*self));	×
179	}
180	})
181	}
182
183	/// Converts a value from [`code_consts`] to a code.
184	///
185	/// # Errors
186	///
187	/// Returns [`DispatchError::UnsupportedCodeConst`] if the value
188	/// does not correspond to any known code constant.
189	pub const fn from_code_const(const_code: usize) -> Result<Self, DispatchError> {	×
190	Ok(match const_code {	×
191	code_consts::UNARY => Self::Unary,	×
192	code_consts::GAMMA => Self::Gamma,	×
193	code_consts::DELTA => Self::Delta,	×
194	code_consts::OMEGA => Self::Omega,	×
195	code_consts::VBYTE_LE => Self::VByteLe,	×
196	code_consts::VBYTE_BE => Self::VByteBe,	×
197	code_consts::ZETA2 => Self::Zeta(2),	×
198	code_consts::ZETA3 => Self::Zeta(3),	×
199	code_consts::ZETA4 => Self::Zeta(4),	×
200	code_consts::ZETA5 => Self::Zeta(5),	×
201	code_consts::ZETA6 => Self::Zeta(6),	×
202	code_consts::ZETA7 => Self::Zeta(7),	×
203	code_consts::ZETA8 => Self::Zeta(8),	×
204	code_consts::ZETA9 => Self::Zeta(9),	×
205	code_consts::ZETA10 => Self::Zeta(10),	×
206	code_consts::RICE1 => Self::Rice(1),	×
207	code_consts::RICE2 => Self::Rice(2),	×
208	code_consts::RICE3 => Self::Rice(3),	×
209	code_consts::RICE4 => Self::Rice(4),	×
210	code_consts::RICE5 => Self::Rice(5),	×
211	code_consts::RICE6 => Self::Rice(6),	×
212	code_consts::RICE7 => Self::Rice(7),	×
213	code_consts::RICE8 => Self::Rice(8),	×
214	code_consts::RICE9 => Self::Rice(9),	×
215	code_consts::RICE10 => Self::Rice(10),	×
216	code_consts::PI1 => Self::Pi(1),	×
217	code_consts::PI2 => Self::Pi(2),	×
218	code_consts::PI3 => Self::Pi(3),	×
219	code_consts::PI4 => Self::Pi(4),	×
220	code_consts::PI5 => Self::Pi(5),	×
221	code_consts::PI6 => Self::Pi(6),	×
222	code_consts::PI7 => Self::Pi(7),	×
223	code_consts::PI8 => Self::Pi(8),	×
224	code_consts::PI9 => Self::Pi(9),	×
225	code_consts::PI10 => Self::Pi(10),	×
226	code_consts::GOLOMB3 => Self::Golomb(3),	×
227	code_consts::GOLOMB5 => Self::Golomb(5),	×
228	code_consts::GOLOMB6 => Self::Golomb(6),	×
229	code_consts::GOLOMB7 => Self::Golomb(7),	×
230	code_consts::GOLOMB9 => Self::Golomb(9),	×
231	code_consts::GOLOMB10 => Self::Golomb(10),	×
232	code_consts::EXP_GOLOMB1 => Self::ExpGolomb(1),	×
233	code_consts::EXP_GOLOMB2 => Self::ExpGolomb(2),	×
234	code_consts::EXP_GOLOMB3 => Self::ExpGolomb(3),	×
235	code_consts::EXP_GOLOMB4 => Self::ExpGolomb(4),	×
236	code_consts::EXP_GOLOMB5 => Self::ExpGolomb(5),	×
237	code_consts::EXP_GOLOMB6 => Self::ExpGolomb(6),	×
238	code_consts::EXP_GOLOMB7 => Self::ExpGolomb(7),	×
239	code_consts::EXP_GOLOMB8 => Self::ExpGolomb(8),	×
240	code_consts::EXP_GOLOMB9 => Self::ExpGolomb(9),	×
241	code_consts::EXP_GOLOMB10 => Self::ExpGolomb(10),	×
242	_ => return Err(DispatchError::UnsupportedCodeConst(const_code)),	×
243	})
244	}
245	}
246
247	impl DynamicCodeRead for Codes {
248	#[inline]
249	fn read<E: Endianness, CR: CodesRead<E> + ?Sized>(	230,372✔
250	&self,
251	reader: &mut CR,
252	) -> Result<u64, CR::Error> {
253	Ok(match self.canonicalize() {	230,372✔
254	Codes::Unary => reader.read_unary()?,	24,660✔
255	Codes::Gamma => reader.read_gamma()?,	34,960✔
256	Codes::Delta => reader.read_delta()?,	8,740✔
257	Codes::Omega => reader.read_omega()?,	8,740✔
258	Codes::VByteBe => reader.read_vbyte_be()?,	8,748✔
259	Codes::VByteLe => reader.read_vbyte_le()?,	8,748✔
260	Codes::Zeta(3) => reader.read_zeta3()?,	8,740✔
261	Codes::Zeta(k) => reader.read_zeta(k)?,	122,080✔
262	Codes::Pi(2) => reader.read_pi2()?,	8,712✔
263	Codes::Pi(k) => reader.read_pi(k)?,	139,504✔
264	Codes::Golomb(b) => reader.read_golomb(b)?,	82,080✔
265	Codes::ExpGolomb(k) => reader.read_exp_golomb(k)?,	156,960✔
266	Codes::Rice(log2_b) => reader.read_rice(log2_b)?,	196,768✔
267	})
268	}
269	}
270
271	impl DynamicCodeWrite for Codes {
272	#[inline]
273	fn write<E: Endianness, CW: CodesWrite<E> + ?Sized>(	230,372✔
274	&self,
275	writer: &mut CW,
276	n: u64,
277	) -> Result<usize, CW::Error> {
278	Ok(match self.canonicalize() {	230,372✔
279	Codes::Unary => writer.write_unary(n)?,	36,990✔
280	Codes::Gamma => writer.write_gamma(n)?,	52,440✔
281	Codes::Delta => writer.write_delta(n)?,	13,110✔
282	Codes::Omega => writer.write_omega(n)?,	13,110✔
283	Codes::VByteBe => writer.write_vbyte_be(n)?,	13,122✔
284	Codes::VByteLe => writer.write_vbyte_le(n)?,	13,122✔
285	Codes::Zeta(3) => writer.write_zeta3(n)?,	13,110✔
286	Codes::Zeta(k) => writer.write_zeta(n, k)?,	152,600✔
287	Codes::Pi(2) => writer.write_pi2(n)?,	13,068✔
288	Codes::Pi(k) => writer.write_pi(n, k)?,	174,380✔
289	Codes::Golomb(b) => writer.write_golomb(n, b)?,	102,600✔
290	Codes::ExpGolomb(k) => writer.write_exp_golomb(n, k)?,	196,200✔
291	Codes::Rice(log2_b) => writer.write_rice(n, log2_b)?,	245,960✔
292	})
293	}
294	}
295
296	impl<E: Endianness, CR: CodesRead<E> + ?Sized> StaticCodeRead<E, CR> for Codes {
297	#[inline(always)]
298	fn read(&self, reader: &mut CR) -> Result<u64, CR::Error> {	115,032✔
299	<Self as DynamicCodeRead>::read(self, reader)	345,096✔
300	}
301	}
302
303	impl<E: Endianness, CW: CodesWrite<E> + ?Sized> StaticCodeWrite<E, CW> for Codes {
304	#[inline(always)]
305	fn write(&self, writer: &mut CW, n: u64) -> Result<usize, CW::Error> {	115,032✔
306	<Self as DynamicCodeWrite>::write(self, writer, n)	460,128✔
307	}
308	}
309
310	impl CodeLen for Codes {
311	#[inline]
312	fn len(&self, n: u64) -> usize {	230,372✔
313	match self.canonicalize() {	230,372✔
314	// The checked conversion avoids truncation on 32-bit platforms
315	Codes::Unary => n	12,330✔
316	.checked_add(1)
317	.and_then(\|len\| usize::try_from(len).ok())	49,320✔
318	.expect("unary code length does not fit in a usize"),
319	Codes::Gamma => len_gamma(n),	34,960✔
320	Codes::Delta => len_delta(n),	8,740✔
321	Codes::Omega => len_omega(n),	8,740✔
322	Codes::VByteLe \| Codes::VByteBe => bit_len_vbyte(n),	17,496✔
323	Codes::Zeta(k) => len_zeta(n, k),	139,560✔
324	Codes::Pi(k) => len_pi(n, k),	156,928✔
325	Codes::Golomb(b) => len_golomb(n, b),	82,080✔
326	Codes::ExpGolomb(k) => len_exp_golomb(n, k),	156,960✔
327	Codes::Rice(log2_b) => len_rice(n, log2_b),	196,768✔
328	}
329	}
330	}
331
332	#[cfg(feature = "serde")]
333	impl serde::Serialize for Codes {
NEW 334	fn serialize<S: serde::Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {	×
NEW 335	serializer.serialize_str(&self.to_string())	×
336	}
337	}
338
339	#[cfg(feature = "serde")]
340	impl<'de> serde::Deserialize<'de> for Codes {
NEW 341	fn deserialize<D: serde::Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {	×
NEW 342	let s = String::deserialize(deserializer)?;	×
NEW 343	s.parse().map_err(serde::de::Error::custom)	×
344	}
345	}
346
347	impl core::fmt::Display for Codes {
348	fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {	×
349	match self {	×
350	Codes::Unary => write!(f, "Unary"),	×
351	Codes::Gamma => write!(f, "Gamma"),	×
352	Codes::Delta => write!(f, "Delta"),	×
353	Codes::Omega => write!(f, "Omega"),	×
354	Codes::VByteBe => write!(f, "VByteBe"),	×
355	Codes::VByteLe => write!(f, "VByteLe"),	×
356	Codes::Zeta(k) => write!(f, "Zeta({})", k),	×
357	Codes::Pi(k) => write!(f, "Pi({})", k),	×
358	Codes::Golomb(b) => write!(f, "Golomb({})", b),	×
359	Codes::ExpGolomb(k) => write!(f, "ExpGolomb({})", k),	×
360	Codes::Rice(log2_b) => write!(f, "Rice({})", log2_b),	×
361	}
362	}
363	}
364
365	fn array_format_error(s: &str) -> [u8; 32] {	10✔
366	let mut error_buffer = [0u8; 32];	20✔
367	let len = s.len().min(32);	40✔
368	error_buffer[..len].copy_from_slice(&s.as_bytes()[..len]);	30✔
369	error_buffer	10✔
370	}
371
372	impl core::str::FromStr for Codes {
373	type Err = CodeError;
374
375	fn from_str(s: &str) -> Result<Self, Self::Err> {	18✔
376	match s {	18✔
377	"Unary" => Ok(Codes::Unary),	19✔
378	"Gamma" => Ok(Codes::Gamma),	17✔
379	"Delta" => Ok(Codes::Delta),	17✔
380	"Omega" => Ok(Codes::Omega),	17✔
381	"VByteBe" => Ok(Codes::VByteBe),	17✔
382	"VByteLe" => Ok(Codes::VByteLe),	17✔
383
384	_ => {
385	// Strict grammar: exactly `Name(param)` with `param` a single
386	// integer and nothing after the closing parenthesis. The former
387	// `split` accepted trailing/incomplete text (e.g. `Zeta(3)x`).
388	let inner = s	32✔
389	.strip_suffix(')')
390	.ok_or_else(\|\| CodeError::UnknownCode(array_format_error(s)))?;	23✔
391	let (name, param) = inner	45✔
392	.split_once('(')
393	.ok_or_else(\|\| CodeError::UnknownCode(array_format_error(s)))?;	15✔
394	if param.contains('(') \|\| param.contains(')') {	58✔
395	return Err(CodeError::UnknownCode(array_format_error(s)));	1✔
396	}
397	let invalid = \|\| CodeError::InvalidParameter(array_format_error(s));	26✔
398	match name {	14✔
399	// zeta is defined for k in [1..64).
400	"Zeta" => {	14✔
401	let k: usize = param.parse()?;	15✔
402	if k == 0 \|\| k >= 64 {	5✔
403	return Err(invalid());	2✔
404	}
405	Ok(Codes::Zeta(k))	1✔
406	}
407	// pi, exponential Golomb and Rice shift by their parameter,
408	// so it must stay below 64.
409	"Pi" => {	10✔
410	let k: usize = param.parse()?;	8✔
411	if k >= 64 {	2✔
412	return Err(invalid());	1✔
413	}
414	Ok(Codes::Pi(k))	1✔
415	}
416	"ExpGolomb" => {	8✔
417	let k: usize = param.parse()?;	8✔
418	if k >= 64 {	2✔
419	return Err(invalid());	1✔
420	}
421	Ok(Codes::ExpGolomb(k))	1✔
422	}
423	"Rice" => {	6✔
424	let k: usize = param.parse()?;	12✔
425	if k >= 64 {	3✔
426	return Err(invalid());	1✔
427	}
428	Ok(Codes::Rice(k))	2✔
429	}
430	// Golomb divides by its modulus, which must be positive.
431	"Golomb" => {	3✔
432	let b: u64 = param.parse()?;	8✔
433	if b == 0 {	2✔
434	return Err(invalid());	1✔
435	}
436	Ok(Codes::Golomb(b))	1✔
437	}
438	_ => Err(CodeError::UnknownCode(array_format_error(name))),	1✔
439	}
440	}
441	}
442	}
443	}
444
445	/// Error type for parsing a code from a string.
446	#[derive(Debug, Clone)]
447	pub enum CodeError {
448	/// Error parsing an integer parameter.
449	ParseError(core::num::ParseIntError),
450	/// Unknown code name. Uses a fixed-size array instead of `String` for `no_std` compatibility.
451	UnknownCode([u8; 32]),
452	/// A parameter is outside the valid range for its code (for example
453	/// `Golomb(0)`, `Zeta(0)`, or a shift parameter `>= 64`).
454	InvalidParameter([u8; 32]),
455	}
456	impl core::error::Error for CodeError {}
457	impl core::fmt::Display for CodeError {
NEW 458	fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {	×
NEW 459	match self {	×
NEW 460	CodeError::ParseError(e) => write!(f, "parse error: {}", e),	×
NEW 461	CodeError::UnknownCode(s) => {	×
NEW 462	write!(f, "unknown code: ")?;	×
NEW 463	for c in s {	×
NEW 464	if *c == 0 {	×
NEW 465	break;	×
466	}
NEW 467	write!(f, "{}", *c as char)?;	×
468	}
NEW 469	Ok(())	×
470	}
NEW 471	CodeError::InvalidParameter(s) => {	×
NEW 472	write!(f, "invalid parameter for code: ")?;	×
NEW 473	for c in s {	×
NEW 474	if *c == 0 {	×
NEW 475	break;	×
476	}
NEW 477	write!(f, "{}", *c as char)?;	×
478	}
NEW 479	Ok(())	×
480	}
481	}
482	}
483	}
484
485	impl From<core::num::ParseIntError> for CodeError {
486	fn from(e: core::num::ParseIntError) -> Self {	1✔
487	CodeError::ParseError(e)	1✔
488	}
489	}
490
491	/// Structure representing minimal binary coding with a fixed upper bound.
492	///
493	/// [Minimal binary coding] does not fit the [`Codes`] enum because it is not
494	/// defined for all integers.
495	///
496	/// Instances of this structure can be used in contexts in which a
497	/// [`DynamicCodeRead`], [`DynamicCodeWrite`], [`StaticCodeRead`],
498	/// [`StaticCodeWrite`] or [`CodeLen`] implementing minimal binary coding
499	/// is necessary.
500	///
501	/// [Minimal binary coding]: crate::codes::minimal_binary
502	#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
503	pub struct MinimalBinary(
504	/// The upper bound of the minimal binary code.
505	pub u64,
506	);
507
508	impl DynamicCodeRead for MinimalBinary {
509	fn read<E: Endianness, R: CodesRead<E> + ?Sized>(	48✔
510	&self,
511	reader: &mut R,
512	) -> Result<u64, R::Error> {
513	reader.read_minimal_binary(self.0)	144✔
514	}
515	}
516
517	impl DynamicCodeWrite for MinimalBinary {
518	fn write<E: Endianness, W: CodesWrite<E> + ?Sized>(	48✔
519	&self,
520	writer: &mut W,
521	n: u64,
522	) -> Result<usize, W::Error> {
523	writer.write_minimal_binary(n, self.0)	192✔
524	}
525	}
526
527	impl<E: Endianness, CR: CodesRead<E> + ?Sized> StaticCodeRead<E, CR> for MinimalBinary {
528	fn read(&self, reader: &mut CR) -> Result<u64, CR::Error> {	24✔
529	<Self as DynamicCodeRead>::read(self, reader)	72✔
530	}
531	}
532
533	impl<E: Endianness, CW: CodesWrite<E> + ?Sized> StaticCodeWrite<E, CW> for MinimalBinary {
534	fn write(&self, writer: &mut CW, n: u64) -> Result<usize, CW::Error> {	24✔
535	<Self as DynamicCodeWrite>::write(self, writer, n)	96✔
536	}
537	}
538
539	impl CodeLen for MinimalBinary {
540	fn len(&self, n: u64) -> usize {	48✔
541	len_minimal_binary(n, self.0)	144✔
542	}
543	}
544
545	#[cfg(test)]
546	mod parse_tests {
547	use super::Codes;
548	use core::str::FromStr;
549
550	#[test]
551	fn test_parses_valid_parameterized_codes() {
552	assert_eq!(Codes::from_str("Unary").unwrap(), Codes::Unary);
553	assert_eq!(Codes::from_str("Zeta(3)").unwrap(), Codes::Zeta(3));
554	assert_eq!(Codes::from_str("Pi(2)").unwrap(), Codes::Pi(2));
555	assert_eq!(Codes::from_str("Golomb(7)").unwrap(), Codes::Golomb(7));
556	assert_eq!(
557	Codes::from_str("ExpGolomb(0)").unwrap(),
558	Codes::ExpGolomb(0)
559	);
560	assert_eq!(Codes::from_str("Rice(0)").unwrap(), Codes::Rice(0));
561	assert_eq!(Codes::from_str("Rice(63)").unwrap(), Codes::Rice(63));
562	}
563
564	#[test]
565	fn test_rejects_out_of_range_parameters() {
566	// These previously deserialized into values that panic on first use
567	// (divide-by-zero) or shift by >= 64.
568	assert!(Codes::from_str("Golomb(0)").is_err());
569	assert!(Codes::from_str("Zeta(0)").is_err());
570	assert!(Codes::from_str("Zeta(64)").is_err());
571	assert!(Codes::from_str("Rice(64)").is_err());
572	assert!(Codes::from_str("Pi(64)").is_err());
573	assert!(Codes::from_str("ExpGolomb(64)").is_err());
574	}
575
576	#[test]
577	fn test_rejects_malformed_grammar() {
578	assert!(Codes::from_str("Zeta(3").is_err());
579	assert!(Codes::from_str("Zeta(3)x").is_err());
580	assert!(Codes::from_str("Zeta(3)(4)").is_err());
581	assert!(Codes::from_str("Zeta()").is_err());
582	assert!(Codes::from_str("Nope(1)").is_err());
583	}
584	}

vigna / dsi-bitstream-rs / 29834581278

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