odra-utils 0.7.1

Utilites used by the Odra crates.
Documentation 
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#![cfg_attr(not(feature = "std"), no_std)]

extern crate alloc;

#[cfg(not(feature = "std"))]
use alloc::string::String;

#[cfg(feature = "std")]
use convert_case::{Boundary, Case, Casing};

/// Converts a camel-cased &str to String.
///
/// # Example
///
/// ```
/// use odra_utils::camel_to_snake;
///
/// let camel = "ContractName";
/// let result = camel_to_snake(camel);
///
/// assert_eq!(&result, "contract_name");
/// ```
#[cfg(feature = "std")]
pub fn camel_to_snake(text: &str) -> String {
    text.from_case(Case::UpperCamel)
        .without_boundaries(&[Boundary::UpperDigit, Boundary::LowerDigit])
        .to_case(Case::Snake)
}

/// Calculates the absolute position of the event. Accepts both positive and negative indexing.
///
/// # Examples
///
/// ```
/// use odra_utils::event_absolute_position;
///
/// assert_eq!(event_absolute_position(10, 0), Some(0));
/// assert_eq!(event_absolute_position(10, -1), Some(9));
/// assert_eq!(event_absolute_position(10, 10), None);
/// ```
pub fn event_absolute_position(len: usize, index: i32) -> Option<usize> {
    if index.is_negative() {
        let abs_idx = index.wrapping_abs() as usize;
        if abs_idx > len {
            return None;
        }
        Some(len - abs_idx)
    } else {
        if index as usize >= len {
            return None;
        }
        Some(index as usize)
    }
}

pub static KEY_DELIMITER: &str = "#";

static TABLE: &[u8] = b"0123456789abcdef";

#[inline]
fn hex(byte: u8) -> u8 {
    TABLE[byte as usize]
}

/// Converts the hexadecimal values from the source byte slice into a more readable form,
/// representing each byte in hexadecimal form, in the destination byte slice.
///
/// * It iterates over the source slice `src` and the destination slice `dst` concurrently.
/// * For each byte in the source, it calculates the hexadecimal representation.
/// * It splits the byte into two nibbles (4-bit groups): the higher order 4 bits and the lower order 4 bits.
/// * It converts each nibble into its corresponding hexadecimal representation.
/// * It stores the two hexadecimal representations in two consecutive slots of the destination slice.
///
/// # Example
///
/// ```
/// # use odra_utils::hex_to_slice;
///
/// let mut dst = vec![0; 10];
/// let src = [255, 254, 253, 252, 251];
/// hex_to_slice(&src, &mut dst);
/// assert_eq!(&dst, &[102, 102, 102, 101, 102, 100, 102, 99, 102, 98]);
/// ```
pub fn hex_to_slice(src: &[u8], dst: &mut [u8]) {
    for (byte, slots) in src.iter().zip(dst.chunks_exact_mut(2)) {
        slots[0] = hex((*byte >> 4) & 0xf);
        slots[1] = hex(*byte & 0xf);
    }
}

/// Joins two parts of a key with the [`KEY_DELIMITER`].
#[inline]
pub fn create_key(left: &str, right: &str) -> String {
    alloc::format!("{}{}{}", left, KEY_DELIMITER, right)
}

#[cfg(test)]
mod tests {
    use crate::{camel_to_snake, event_absolute_position};

    #[test]
    fn camel_to_snake_works() {
        assert_eq!("owned_token", camel_to_snake("OwnedToken"));
        assert_eq!("ownable", camel_to_snake("Ownable"));
        assert_eq!("erc20", camel_to_snake("Erc20"));
        assert_eq!(
            "erc20_implementation",
            camel_to_snake("Erc20Implementation")
        );
    }

    #[test]
    fn event_absolute_position_works() {
        assert_eq!(event_absolute_position(0, 1), None);
        assert_eq!(event_absolute_position(10, 10), None);
        assert_eq!(event_absolute_position(10, -11), None);
        assert_eq!(event_absolute_position(10, 0), Some(0));
        assert_eq!(event_absolute_position(10, 1), Some(1));
        assert_eq!(event_absolute_position(10, -1), Some(9));
        assert_eq!(event_absolute_position(10, -2), Some(8));
        assert_eq!(event_absolute_position(10, -10), Some(0));
    }
}