feat: ByteArray type

starknet-core/src/types/byte_array.rs

@@ -0,0 +1,222 @@
+use alloc::{string::*, vec::*};
+
+use num_traits::ToPrimitive;
+
+use crate::{
+    codec::{Decode, Encode, Error as CodecError, FeltWriter},
+    types::Felt,
+};
+
+const BYTES_PER_SLOT: usize = 31;
+const FELT_BYTE_SIZE: usize = 32;
+
+/// The `ByteArray` type in Cairo.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct ByteArray(Vec<u8>);
+
+impl ByteArray {
+    /// Returns the number of bytes in the array, also referred to as its 'length'.
+    pub fn len(&self) -> usize {
+        self.0.len()
+    }
+
+    /// Returns `true` if the array contains no bytes.
+    #[must_use]
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+}
+
+impl From<Vec<u8>> for ByteArray {
+    fn from(value: Vec<u8>) -> Self {
+        Self(value)
+    }
+}
+
+impl From<&str> for ByteArray {
+    fn from(value: &str) -> Self {
+        Self(value.as_bytes().to_vec())
+    }
+}
+
+impl From<ByteArray> for Vec<u8> {
+    fn from(value: ByteArray) -> Self {
+        value.0
+    }
+}
+
+impl TryFrom<ByteArray> for String {
+    type Error = FromUtf8Error;
+
+    fn try_from(value: ByteArray) -> Result<Self, Self::Error> {
+        Self::from_utf8(value.0)
+    }
+}
+
+impl Encode for ByteArray {
+    fn encode<W: FeltWriter>(&self, writer: &mut W) -> Result<(), CodecError> {
+        writer.write((self.len() / BYTES_PER_SLOT).into());
+        let mut chunks_iter = self.0.chunks_exact(BYTES_PER_SLOT);
+        for full_slot in chunks_iter.by_ref() {
+            writer.write(Felt::from_bytes_be_slice(full_slot));
+        }
+
+        let last_chunk = chunks_iter.remainder();
+        writer.write(Felt::from_bytes_be_slice(last_chunk));
+        writer.write(last_chunk.len().into());
+
+        Ok(())
+    }
+}
+
+impl<'a> Decode<'a> for ByteArray {
+    fn decode_iter<T>(iter: &mut T) -> Result<Self, CodecError>
+    where
+        T: Iterator<Item = &'a Felt>,
+    {
+        let length = iter.next().ok_or_else(CodecError::input_exhausted)?;
+        let length = length
+            .to_usize()
+            .ok_or_else(|| CodecError::value_out_of_range(length, "usize"))?;
+
+        let mut result = Vec::<u8>::with_capacity(length * BYTES_PER_SLOT + BYTES_PER_SLOT - 1);
+
+        for _ in 0..length {
+            let full_slot = iter.next().ok_or_else(CodecError::input_exhausted)?;
+            result.extend_from_slice(&full_slot.to_bytes_be()[1..]);
+        }
+
+        let pending_word = iter.next().ok_or_else(CodecError::input_exhausted)?;
+        let pending_word_len = iter.next().ok_or_else(CodecError::input_exhausted)?;
+        let pending_word_len = pending_word_len
+            .to_usize()
+            .ok_or_else(|| CodecError::value_out_of_range(pending_word_len, "usize"))?;
+        result
+            .extend_from_slice(&pending_word.to_bytes_be()[(FELT_BYTE_SIZE - pending_word_len)..]);
+
+        Ok(Self(result))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
+    fn test_string_encode_decode_roundtrip() {
+        let test_data = [
+            (
+                "",
+                vec![
+                    Felt::from_hex_unchecked(
+                        "0x0000000000000000000000000000000000000000000000000000000000000000",
+                    ),
+                    Felt::from_hex_unchecked(
+                        "0x0000000000000000000000000000000000000000000000000000000000000000",
+                    ),
+                    Felt::from_hex_unchecked(
+                        "0x0000000000000000000000000000000000000000000000000000000000000000",
+                    ),
+                ],
+            ),
+            (
+                "abc",
+                vec![
+                    Felt::from_hex_unchecked(
+                        "0x0000000000000000000000000000000000000000000000000000000000000000",
+                    ),
+                    Felt::from_hex_unchecked(
+                        "0x0000000000000000000000000000000000000000000000000000000000616263",
+                    ),
+                    Felt::from_hex_unchecked(
+                        "0x0000000000000000000000000000000000000000000000000000000000000003",
+                    ),
+                ],
+            ),
+            (
+                "000000000011111111112222222222",
+                vec![
+                    Felt::from_hex_unchecked(
+                        "0x0000000000000000000000000000000000000000000000000000000000000000",
+                    ),
+                    Felt::from_hex_unchecked(
+                        "0x0000303030303030303030303131313131313131313132323232323232323232",
+                    ),
+                    Felt::from_hex_unchecked(
+                        "0x000000000000000000000000000000000000000000000000000000000000001e",
+                    ),
+                ],
+            ),
+            (
+                "0000000000111111111122222222223",
+                vec![
+                    Felt::from_hex_unchecked(
+                        "0x0000000000000000000000000000000000000000000000000000000000000001",
+                    ),
+                    Felt::from_hex_unchecked(
+                        "0x0030303030303030303030313131313131313131313232323232323232323233",
+                    ),
+                    Felt::from_hex_unchecked(
+                        "0x0000000000000000000000000000000000000000000000000000000000000000",
+                    ),
+                    Felt::from_hex_unchecked(
+                        "0x0000000000000000000000000000000000000000000000000000000000000000",
+                    ),
+                ],
+            ),
+            (
+                "00000000001111111111222222222233",
+                vec![
+                    Felt::from_hex_unchecked(
+                        "0x0000000000000000000000000000000000000000000000000000000000000001",
+                    ),
+                    Felt::from_hex_unchecked(
+                        "0x0030303030303030303030313131313131313131313232323232323232323233",
+                    ),
+                    Felt::from_hex_unchecked(
+                        "0x0000000000000000000000000000000000000000000000000000000000000033",
+                    ),
+                    Felt::from_hex_unchecked(
+                        "0x0000000000000000000000000000000000000000000000000000000000000001",
+                    ),
+                ],
+            ),
+            (
+                "00000000001111111111222222222233333333334444444444\
+                 55555555556666666666777777777788888888889999999999",
+                vec![
+                    Felt::from_hex_unchecked(
+                        "0x0000000000000000000000000000000000000000000000000000000000000003",
+                    ),
+                    Felt::from_hex_unchecked(
+                        "0x0030303030303030303030313131313131313131313232323232323232323233",
+                    ),
+                    Felt::from_hex_unchecked(
+                        "0x0033333333333333333334343434343434343434353535353535353535353636",
+                    ),
+                    Felt::from_hex_unchecked(
+                        "0x0036363636363636363737373737373737373738383838383838383838393939",
+                    ),
+                    Felt::from_hex_unchecked(
+                        "0x0000000000000000000000000000000000000000000000000039393939393939",
+                    ),
+                    Felt::from_hex_unchecked(
+                        "0x0000000000000000000000000000000000000000000000000000000000000007",
+                    ),
+                ],
+            ),
+        ];
+
+        for (string, expected) in test_data {
+            let bytes: ByteArray = string.into();
+
+            let mut encoded = vec![];
+            bytes.encode(&mut encoded).unwrap();
+            assert_eq!(encoded, expected);
+
+            let decoded = ByteArray::decode(&expected).unwrap();
+            assert_eq!(String::try_from(decoded).unwrap(), string);
+        }
+    }
+}

starknet-core/src/types/mod.rs

@@ -65,6 +65,9 @@ pub use msg::MsgToL2;
 mod call;
 pub use call::Call;
 
+mod byte_array;
+pub use byte_array::ByteArray;
+
 // TODO: move generated request code to `starknet-providers`
 /// Module containing JSON-RPC request types.
 pub mod requests;