94 lines
3.1 KiB
Rust
94 lines
3.1 KiB
Rust
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use std::{
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io::{Error, Write},
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marker::PhantomData,
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};
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use crate::HaskellSize;
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/*******************************************************************************
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Main class definition
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*******************************************************************************/
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// Copied from `borsh`
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const DEFAULT_SERIALIZER_CAPACITY: usize = 1024;
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pub trait ToHaskell<Tag> {
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/// Serialize data to be sent to Haskell
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///
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/// This is the analogue of `BorshSerialize::serialize`.
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///
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/// The `tag` argument allows client libraries to define additional
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/// instances of `ToHaskell` for foreign (non-local) types. For example, the
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/// `solana-sdk-haskell` library can define a `ToHaskell` instance for
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/// `Keypair`, defined in `solana-sdk`, as long as it uses a tag `Solana`
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/// defined locally in the `solana-haskell-sdk` package.
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fn to_haskell<W: Write>(&self, writer: &mut W, tag: PhantomData<Tag>) -> Result<(), Error>;
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fn to_haskell_vec(&self, tag: PhantomData<Tag>) -> Result<Vec<u8>, Error> {
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let mut result = Vec::with_capacity(DEFAULT_SERIALIZER_CAPACITY);
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self.to_haskell(&mut result, tag)?;
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Ok(result)
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}
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}
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impl<Tag, T: ToHaskell<Tag>> ToHaskell<Tag> for &T {
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fn to_haskell<W: Write>(&self, writer: &mut W, tag: PhantomData<Tag>) -> Result<(), Error> {
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(*self).to_haskell(writer, tag)
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}
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}
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/*******************************************************************************
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Derived functionality
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These functions are not defined in the trait itself, to make it clear that
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they only exist at top-level calls, and will not be recursively called
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in various `ToHaskell` instances. This is important, because the `len`
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parameter that gives the length of the buffer only applies to the _overall_
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buffer.
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*******************************************************************************/
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/// Marshall value with fixed-sized encoding
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///
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/// The `out_len` parameter is only used to verify that the Haskell-side and
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/// the Rust side agree on the length of the encoding.
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pub fn marshall_to_haskell_fixed<Tag, T>(t: &T, out: *mut u8, out_len: usize, tag: PhantomData<Tag>)
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where
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T: HaskellSize<Tag> + ToHaskell<Tag>,
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{
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let expected_len: usize = T::haskell_size(tag);
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if out_len != expected_len {
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panic!(
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"marshall_to_haskell_fixed: expected buffer of size {}, but got {}",
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expected_len, out_len
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)
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} else {
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let mut out_len_copy = out_len;
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marshall_to_haskell_var(t, out, &mut out_len_copy, tag);
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}
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}
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/// Marshall value with variable-sized encoding
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pub fn marshall_to_haskell_var<Tag, T>(
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t: &T,
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out: *mut u8,
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out_len: &mut usize,
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tag: PhantomData<Tag>,
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) where
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T: ToHaskell<Tag>,
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{
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match t.to_haskell_vec(tag) {
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Ok(vec) => {
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let slice: &[u8] = vec.as_ref();
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if slice.len() <= *out_len {
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unsafe {
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std::ptr::copy(slice.as_ptr(), out, slice.len());
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}
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}
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*out_len = slice.len();
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}
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Err(e) => panic!("{}", e),
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}
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}
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