annotate rust/hg-core/src/utils.rs @ 46243:63c923fd7fa8

setup: when possible, build and bundle man pages

This makes it so the manual pages are built as part of the Python
build, and includes them in any wheel generated. This should make
Python wheels a much more useful and complete way of distributing
Mercurial binaries.

Differential Revision: https://phab.mercurial-scm.org/D9640

// utils module
//
// Copyright 2019 Raphaël Gomès <[e-mail]>
//
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2 or any later version.

//! Contains useful functions, traits, structs, etc. for use in core.

use crate::utils::hg_path::HgPath;
use std::{io::Write, ops::Deref};

pub mod files;
pub mod hg_path;
pub mod path_auditor;

/// Useful until rust/issues/56345 is stable
///
/// # Examples
///
/// ```
/// use crate::hg::utils::find_slice_in_slice;
///
/// let haystack = b"This is the haystack".to_vec();
/// assert_eq!(find_slice_in_slice(&haystack, b"the"), Some(8));
/// assert_eq!(find_slice_in_slice(&haystack, b"not here"), None);
/// ```
pub fn find_slice_in_slice<T>(slice: &[T], needle: &[T]) -> Option<usize>
where
    for<'a> &'a [T]: PartialEq,
{
    slice
        .windows(needle.len())
        .position(|window| window == needle)
}

/// Replaces the `from` slice with the `to` slice inside the `buf` slice.
///
/// # Examples
///
/// ```
/// use crate::hg::utils::replace_slice;
/// let mut line = b"I hate writing tests!".to_vec();
/// replace_slice(&mut line, b"hate", b"love");
/// assert_eq!(
///     line,
///     b"I love writing tests!".to_vec()
/// );
/// ```
pub fn replace_slice<T>(buf: &mut [T], from: &[T], to: &[T])
where
    T: Clone + PartialEq,
{
    if buf.len() < from.len() || from.len() != to.len() {
        return;
    }
    for i in 0..=buf.len() - from.len() {
        if buf[i..].starts_with(from) {
            buf[i..(i + from.len())].clone_from_slice(to);
        }
    }
}

pub trait SliceExt {
    fn trim_end(&self) -> &Self;
    fn trim_start(&self) -> &Self;
    fn trim(&self) -> &Self;
    fn drop_prefix(&self, needle: &Self) -> Option<&Self>;
}

#[allow(clippy::trivially_copy_pass_by_ref)]
fn is_not_whitespace(c: &u8) -> bool {
    !(*c as char).is_whitespace()
}

impl SliceExt for [u8] {
    fn trim_end(&self) -> &[u8] {
        if let Some(last) = self.iter().rposition(is_not_whitespace) {
            &self[..=last]
        } else {
            &[]
        }
    }
    fn trim_start(&self) -> &[u8] {
        if let Some(first) = self.iter().position(is_not_whitespace) {
            &self[first..]
        } else {
            &[]
        }
    }

    /// ```
    /// use hg::utils::SliceExt;
    /// assert_eq!(
    ///     b"  to trim  ".trim(),
    ///     b"to trim"
    /// );
    /// assert_eq!(
    ///     b"to trim  ".trim(),
    ///     b"to trim"
    /// );
    /// assert_eq!(
    ///     b"  to trim".trim(),
    ///     b"to trim"
    /// );
    /// ```
    fn trim(&self) -> &[u8] {
        self.trim_start().trim_end()
    }

    fn drop_prefix(&self, needle: &Self) -> Option<&Self> {
        if self.starts_with(needle) {
            Some(&self[needle.len()..])
        } else {
            None
        }
    }
}

pub trait Escaped {
    /// Return bytes escaped for display to the user
    fn escaped_bytes(&self) -> Vec<u8>;
}

impl Escaped for u8 {
    fn escaped_bytes(&self) -> Vec<u8> {
        let mut acc = vec![];
        match self {
            c @ b'\'' | c @ b'\\' => {
                acc.push(b'\\');
                acc.push(*c);
            }
            b'\t' => {
                acc.extend(br"\\t");
            }
            b'\n' => {
                acc.extend(br"\\n");
            }
            b'\r' => {
                acc.extend(br"\\r");
            }
            c if (*c < b' ' || *c >= 127) => {
                write!(acc, "\\x{:x}", self).unwrap();
            }
            c => {
                acc.push(*c);
            }
        }
        acc
    }
}

impl<'a, T: Escaped> Escaped for &'a [T] {
    fn escaped_bytes(&self) -> Vec<u8> {
        self.iter().flat_map(Escaped::escaped_bytes).collect()
    }
}

impl<T: Escaped> Escaped for Vec<T> {
    fn escaped_bytes(&self) -> Vec<u8> {
        self.deref().escaped_bytes()
    }
}

impl<'a> Escaped for &'a HgPath {
    fn escaped_bytes(&self) -> Vec<u8> {
        self.as_bytes().escaped_bytes()
    }
}

// TODO: use the str method when we require Rust 1.45
pub(crate) fn strip_suffix<'a>(s: &'a str, suffix: &str) -> Option<&'a str> {
    if s.ends_with(suffix) {
        Some(&s[..s.len() - suffix.len()])
    } else {
        None
    }
}