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// SPDX-License-Identifier: CC0-1.0
//! Bitcoin string parsing utilities.
//!
//! This module provides utility types and traits
//! to support handling and parsing strings within `rust-bitcoin`.
use core::fmt;
use internals::write_err;
use crate::prelude::String;
/// Trait that allows types to be initialized from hex strings
pub trait FromHexStr: Sized {
/// An error occurred while parsing the hex string.
type Error;
/// Parses provided string as hex requiring 0x prefix.
///
/// This is intended for user-supplied inputs or already-existing protocols in which 0x prefix is used.
fn from_hex_str<S: AsRef<str> + Into<String>>(s: S) -> Result<Self, FromHexError<Self::Error>> {
if !s.as_ref().starts_with("0x") {
Err(FromHexError::MissingPrefix(s.into()))
} else {
Ok(Self::from_hex_str_no_prefix(s.as_ref().trim_start_matches("0x"))?)
}
}
/// Parses provided string as hex without requiring 0x prefix.
///
/// This is **not** recommended for user-supplied inputs because of possible confusion with decimals.
/// It should be only used for existing protocols which always encode values as hex without 0x prefix.
fn from_hex_str_no_prefix<S: AsRef<str> + Into<String>>(s: S) -> Result<Self, Self::Error>;
}
/// Hex parsing error
#[derive(Debug, Clone, PartialEq, Eq)]
#[non_exhaustive]
pub enum FromHexError<E> {
/// The input was not a valid hex string, contains the error that occurred while parsing.
ParseHex(E),
/// The input is missing `0x` prefix, contains the invalid input.
MissingPrefix(String),
}
impl<E> From<E> for FromHexError<E> {
fn from(e: E) -> Self { FromHexError::ParseHex(e) }
}
impl<E: fmt::Display> fmt::Display for FromHexError<E> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
use FromHexError::*;
match *self {
ParseHex(ref e) => write_err!(f, "failed to parse hex string"; e),
MissingPrefix(ref value) =>
write_err!(f, "the input value `{}` is missing the `0x` prefix", value; self),
}
}
}
#[cfg(feature = "std")]
impl<E> std::error::Error for FromHexError<E>
where
E: std::error::Error + 'static,
{
fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
use FromHexError::*;
match *self {
ParseHex(ref e) => Some(e),
MissingPrefix(_) => None,
}
}
}