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// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// Copyright by contributors to this project.
// SPDX-License-Identifier: (Apache-2.0 OR MIT)
use core::fmt::{self, Debug};
const DEFAULT_BYTES_TYPE_NAME: &str = "Bytes";
pub fn pretty_bytes(bytes: &[u8]) -> PrettyBytes<'_> {
PrettyBytes {
ty: None,
bytes,
show_len: true,
show_raw: false,
}
}
pub struct PrettyBytes<'a> {
ty: Option<&'a str>,
bytes: &'a [u8],
show_len: bool,
show_raw: bool,
}
impl<'a> PrettyBytes<'a> {
pub fn named(self, ty: &'a str) -> Self {
Self {
ty: Some(ty),
..self
}
}
pub fn show_len(self, show: bool) -> Self {
Self {
show_len: show,
..self
}
}
pub fn show_raw(self, show: bool) -> Self {
Self {
show_raw: show,
..self
}
}
}
impl Debug for PrettyBytes<'_> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let show_raw = self.show_raw || f.alternate();
match (self.ty, self.show_len, show_raw) {
(_, false, false) => show_only_type(self.ty, f),
(None, false, true) => show_only_raw(self.bytes, f),
(Some(ty), false, true) => show_newtype(ty, self.bytes, f),
(_, true, _) => show_struct(self.ty, self.bytes, show_raw, f),
}
}
}
fn show_only_type(ty: Option<&str>, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.write_str(ty.unwrap_or(DEFAULT_BYTES_TYPE_NAME))
}
fn show_only_raw(bytes: &[u8], f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.write_str(&hex::encode(bytes))
}
fn show_newtype(ty: &str, bytes: &[u8], f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{ty}({})", hex::encode(bytes))
}
fn show_struct(
ty: Option<&str>,
bytes: &[u8],
show_raw: bool,
f: &mut fmt::Formatter<'_>,
) -> fmt::Result {
let ty = ty.unwrap_or(DEFAULT_BYTES_TYPE_NAME);
let mut out = f.debug_struct(ty);
out.field("len", &bytes.len());
if show_raw {
out.field("raw", &hex::encode(bytes));
}
out.finish()
}
pub fn pretty_with<F>(f: F) -> impl Debug
where
F: Fn(&mut fmt::Formatter<'_>) -> fmt::Result,
{
PrettyWith(f)
}
struct PrettyWith<F>(F);
impl<F> Debug for PrettyWith<F>
where
F: Fn(&mut fmt::Formatter<'_>) -> fmt::Result,
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.0(f)
}
}
pub fn pretty_group_id(id: &[u8]) -> impl Debug + '_ {
pretty_bytes(id).show_len(false).show_raw(true)
}
#[cfg(test)]
mod tests {
use crate::debug::pretty_bytes;
#[test]
fn default_format_contains_only_length() {
let bytes = pretty_bytes(b"foobar");
let output = format!("{bytes:?}");
assert!(output.contains("len"));
assert!(!output.contains("raw"));
assert!(!output.contains(&hex::encode(b"foobar")));
}
#[test]
fn alternate_format_contains_length_and_hex_encoded_bytes() {
let bytes = pretty_bytes(b"foobar");
let output = format!("{bytes:#?}");
assert!(output.contains("len"));
assert!(output.contains("raw"));
assert!(output.contains(&hex::encode(b"foobar")));
}
}