carbon_core/

deserialize.rs

//! Provides traits and utility functions for deserialization and account
//! arrangement within the `carbon-core` framework.
//!
//! This module includes the `CarbonDeserialize` trait for custom
//! deserialization of data types, the `extract_discriminator` function for
//! splitting data slices by a discriminator length, and the `ArrangeAccounts`
//! trait for defining of Solana account metadata.
//!
//! # Overview
//!
//! - **`CarbonDeserialize`**: A trait for custom deserialization of data
//!   structures from byte slices.
//! - **`extract_discriminator`**: A function that separates a discriminator
//!   from the rest of a byte slice, used for parsing data with prefixed
//!   discriminators.
//! - **`ArrangeAccounts`**: A trait that allows for defining a specific
//!   arrangement of accounts, suitable for handling Solana account metadata in
//!   a customized way.
//!
//! # Notes
//!
//! - The `CarbonDeserialize` trait requires implementers to also implement
//!   `borsh::BorshDeserialize`.
//! - Ensure that `extract_discriminator` is used with data slices large enough
//!   to avoid runtime errors.
//! - Implement `ArrangeAccounts` when you need to access account metadata for
//!   Solana instructions.

use std::{
    io::{Error, ErrorKind, Read, Result},
    ops::Deref,
};
/// A trait for custom deserialization of types from byte slices.
///
/// The `CarbonDeserialize` trait provides a method for deserializing instances
/// of a type from raw byte slices. This is essential for parsing binary data
/// into structured types within the `carbon-core` framework. Types implementing
/// this trait should also implement `BorshDeserialize` to support Borsh-based
/// serialization.
///
/// # Notes
///
/// - Implementing this trait enables custom deserialization logic for types,
///   which is useful for processing raw blockchain data.
/// - Ensure the data slice passed to `deserialize` is valid and of appropriate
///   length to avoid errors.
pub trait CarbonDeserialize
where
    Self: Sized + crate::borsh::BorshDeserialize,
{
    const DISCRIMINATOR: &'static [u8];

    fn deserialize(data: &[u8]) -> Option<Self>;
}

/// Extracts a discriminator from the beginning of a byte slice and returns the
/// discriminator and remaining data.
///
/// The `extract_discriminator` function takes a slice of bytes and separates a
/// portion of it, specified by the `length` parameter, from the rest of the
/// data. This is commonly used in scenarios where data is prefixed with a
/// discriminator value, such as Solana transactions and accounts.
///
/// # Parameters
///
/// - `length`: The length of the discriminator prefix to extract.
/// - `data`: The full data slice from which to extract the discriminator.
///
/// # Returns
///
/// Returns an `Option` containing a tuple of slices:
/// - The first slice is the discriminator of the specified length.
/// - The second slice is the remaining data following the discriminator.
///   Returns `None` if the `data` slice is shorter than the specified `length`.
///
/// # Notes
///
/// - Ensure that `data` is at least as long as `length` to avoid `None` being
///   returned.
/// - This function is particularly useful for decoding prefixed data
///   structures, such as those commonly found in Solana transactions.
pub fn extract_discriminator(length: usize, data: &[u8]) -> Option<(&[u8], &[u8])> {
    log::trace!(
        "extract_discriminator(length: {:?}, data: {:?})",
        length,
        data
    );

    if data.len() < length {
        return None;
    }

    Some((&data[..length], &data[length..]))
}

/// A trait for defining a custom arrangement of Solana account metadata.
///
/// The `ArrangeAccounts` trait provides an interface for structuring account
/// metadata in a custom format.
///
/// # Associated Types
///
/// - `ArrangedAccounts`: The output type representing the custom arrangement of
///   accounts.
pub trait ArrangeAccounts {
    type ArrangedAccounts;

    fn arrange_accounts(
        accounts: &[solana_instruction::AccountMeta],
    ) -> Option<Self::ArrangedAccounts>;
}

/// A wrapper type for strings that are prefixed with their length.

#[derive(serde::Serialize, serde::Deserialize, Default, PartialEq, Eq, Clone)]
pub struct PrefixString(pub String);

impl Deref for PrefixString {
    type Target = String;

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}

impl From<PrefixString> for String {
    fn from(val: PrefixString) -> Self {
        val.0
    }
}

impl std::fmt::Debug for PrefixString {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_fmt(format_args!("{:?}", self.0))
    }
}

/// Implements the `CarbonDeserialize` trait for `PrefixString`.
impl crate::borsh::BorshDeserialize for PrefixString {
    #[inline]
    fn deserialize_reader<R: Read>(reader: &mut R) -> Result<Self> {
        // read the length of the String
        let mut buffer = vec![0u8; 4];
        reader.read_exact(&mut buffer)?;
        let length = u32::deserialize(&mut buffer.as_slice())?;
        let mut buffer = vec![0u8; length as usize];
        reader.read_exact(&mut buffer)?;

        Ok(Self(String::from_utf8(buffer).map_err(|_| {
            Error::new(ErrorKind::InvalidData, "invalid utf8")
        })?))
    }
}

/// A wrapper type for strings that are prefixed with their length.

#[derive(serde::Serialize, Default, serde::Deserialize, PartialEq, Eq, Clone)]
pub struct U64PrefixString(pub String);

impl Deref for U64PrefixString {
    type Target = String;

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}

impl From<U64PrefixString> for String {
    fn from(val: U64PrefixString) -> Self {
        val.0
    }
}

impl std::fmt::Debug for U64PrefixString {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_fmt(format_args!("{:?}", self.0))
    }
}

/// Implements the `CarbonDeserialize` trait for `U64PrefixString`.
impl crate::borsh::BorshDeserialize for U64PrefixString {
    #[inline]
    fn deserialize_reader<R: Read>(reader: &mut R) -> Result<Self> {
        // read the length of the String
        let mut buffer = vec![0u8; 8];
        reader.read_exact(&mut buffer)?;
        let length = u64::deserialize(&mut buffer.as_slice())?;
        let mut buffer = vec![0u8; length as usize];
        reader.read_exact(&mut buffer)?;

        Ok(Self(String::from_utf8(buffer).map_err(|_| {
            Error::new(ErrorKind::InvalidData, "invalid utf8")
        })?))
    }
}