view rust/hg-core/src/filepatterns.rs @ 42609:326fdce22fb2

rust: switch hg-core and hg-cpython to rust 2018 edition

Many interesting changes have happened in Rust since the Oxidation Plan was
introduced, like the 2018 edition and procedural macros:

    - Opting in to the 2018 edition is a clear benefit in terms of future
      proofing, new (nice to have) syntactical sugar notwithstanding. It
      also has a new non-lexical, non-AST based borrow checker that has
      fewer bugs(!) and allows us to write correct code that in some cases
      would have been rejected by the old one.
    - Procedural macros allow us to use the PyO3 crate which maintainers have
      expressed the clear goal of compiling on stable, which would help in
      code maintainability compared to rust-cpython.

In this patch are the following changes:
    - Removing most `extern crate` uses
    - Updating `use` clauses (`crate` keyword, nested `use`)
    - Removing `mod.rs` in favor of an aptly named module file

Like discussed in the mailing list (
https://www.mercurial-scm.org/pipermail/mercurial-devel/2019-July/132316.html
), until Rust integration in Mercurial is considered to be out of the
experimental phase, the maximum version of Rust allowed is whatever the latest
version Debian packages.

Differential Revision: https://phab.mercurial-scm.org/D6597

use crate::{
    utils::{files::get_path_from_bytes, replace_slice, SliceExt},
    LineNumber, PatternError, PatternFileError,
};
use lazy_static::lazy_static;
use regex::bytes::Regex;
use std::collections::HashMap;
use std::fs::File;
use std::io::Read;
use std::vec::Vec;

lazy_static! {
    static ref RE_ESCAPE: Vec<Vec<u8>> = {
        let mut v: Vec<Vec<u8>> = (0..=255).map(|byte| vec![byte]).collect();
        let to_escape = b"()[]{}?*+-|^$\\.&~# \t\n\r\x0b\x0c";
        for byte in to_escape {
            v[*byte as usize].insert(0, b'\\');
        }
        v
    };
}

/// These are matched in order
const GLOB_REPLACEMENTS: &[(&[u8], &[u8])] =
    &[(b"*/", b"(?:.*/)?"), (b"*", b".*"), (b"", b"[^/]*")];

#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub enum PatternSyntax {
    Regexp,
    /// Glob that matches at the front of the path
    RootGlob,
    /// Glob that matches at any suffix of the path (still anchored at slashes)
    Glob,
    Path,
    RelPath,
    RelGlob,
    RelRegexp,
    RootFiles,
}

/// Transforms a glob pattern into a regex
fn glob_to_re(pat: &[u8]) -> Vec<u8> {
    let mut input = pat;
    let mut res: Vec<u8> = vec![];
    let mut group_depth = 0;

    while let Some((c, rest)) = input.split_first() {
        input = rest;

        match c {
            b'*' => {
                for (source, repl) in GLOB_REPLACEMENTS {
                    if input.starts_with(source) {
                        input = &input[source.len()..];
                        res.extend(*repl);
                        break;
                    }
                }
            }
            b'?' => res.extend(b"."),
            b'[' => {
                match input.iter().skip(1).position(|b| *b == b']') {
                    None => res.extend(b"\\["),
                    Some(end) => {
                        // Account for the one we skipped
                        let end = end + 1;

                        res.extend(b"[");

                        for (i, b) in input[..end].iter().enumerate() {
                            if *b == b'!' && i == 0 {
                                res.extend(b"^")
                            } else if *b == b'^' && i == 0 {
                                res.extend(b"\\^")
                            } else if *b == b'\\' {
                                res.extend(b"\\\\")
                            } else {
                                res.push(*b)
                            }
                        }
                        res.extend(b"]");
                        input = &input[end + 1..];
                    }
                }
            }
            b'{' => {
                group_depth += 1;
                res.extend(b"(?:")
            }
            b'}' if group_depth > 0 => {
                group_depth -= 1;
                res.extend(b")");
            }
            b',' if group_depth > 0 => res.extend(b"|"),
            b'\\' => {
                let c = {
                    if let Some((c, rest)) = input.split_first() {
                        input = rest;
                        c
                    } else {
                        c
                    }
                };
                res.extend(&RE_ESCAPE[*c as usize])
            }
            _ => res.extend(&RE_ESCAPE[*c as usize]),
        }
    }
    res
}

fn escape_pattern(pattern: &[u8]) -> Vec<u8> {
    pattern
        .iter()
        .flat_map(|c| RE_ESCAPE[*c as usize].clone())
        .collect()
}

fn parse_pattern_syntax(kind: &[u8]) -> Result<PatternSyntax, PatternError> {
    match kind {
        b"re" => Ok(PatternSyntax::Regexp),
        b"path" => Ok(PatternSyntax::Path),
        b"relpath" => Ok(PatternSyntax::RelPath),
        b"rootfilesin" => Ok(PatternSyntax::RootFiles),
        b"relglob" => Ok(PatternSyntax::RelGlob),
        b"relre" => Ok(PatternSyntax::RelRegexp),
        b"glob" => Ok(PatternSyntax::Glob),
        b"rootglob" => Ok(PatternSyntax::RootGlob),
        _ => Err(PatternError::UnsupportedSyntax(
            String::from_utf8_lossy(kind).to_string(),
        )),
    }
}

/// Builds the regex that corresponds to the given pattern.
/// If within a `syntax: regexp` context, returns the pattern,
/// otherwise, returns the corresponding regex.
fn _build_single_regex(
    syntax: PatternSyntax,
    pattern: &[u8],
    globsuffix: &[u8],
) -> Vec<u8> {
    if pattern.is_empty() {
        return vec![];
    }
    match syntax {
        PatternSyntax::Regexp => pattern.to_owned(),
        PatternSyntax::RelRegexp => {
            if pattern[0] == b'^' {
                return pattern.to_owned();
            }
            let mut res = b".*".to_vec();
            res.extend(pattern);
            res
        }
        PatternSyntax::Path | PatternSyntax::RelPath => {
            if pattern == b"." {
                return vec![];
            }
            let mut pattern = escape_pattern(pattern);
            pattern.extend(b"(?:/|$)");
            pattern
        }
        PatternSyntax::RootFiles => {
            let mut res = if pattern == b"." {
                vec![]
            } else {
                // Pattern is a directory name.
                let mut as_vec: Vec<u8> = escape_pattern(pattern);
                as_vec.push(b'/');
                as_vec
            };

            // Anything after the pattern must be a non-directory.
            res.extend(b"[^/]+$");
            res
        }
        PatternSyntax::Glob
        | PatternSyntax::RelGlob
        | PatternSyntax::RootGlob => {
            let mut res: Vec<u8> = vec![];
            if syntax == PatternSyntax::RelGlob {
                res.extend(b"(?:|.*/)");
            }

            res.extend(glob_to_re(pattern));
            res.extend(globsuffix.iter());
            res
        }
    }
}

const GLOB_SPECIAL_CHARACTERS: [u8; 7] =
    [b'*', b'?', b'[', b']', b'{', b'}', b'\\'];

/// Wrapper function to `_build_single_regex` that short-circuits 'exact' globs
/// that don't need to be transformed into a regex.
pub fn build_single_regex(
    kind: &[u8],
    pat: &[u8],
    globsuffix: &[u8],
) -> Result<Vec<u8>, PatternError> {
    let enum_kind = parse_pattern_syntax(kind)?;
    if enum_kind == PatternSyntax::RootGlob
        && !pat.iter().any(|b| GLOB_SPECIAL_CHARACTERS.contains(b))
    {
        let mut escaped = escape_pattern(pat);
        escaped.extend(b"(?:/|$)");
        Ok(escaped)
    } else {
        Ok(_build_single_regex(enum_kind, pat, globsuffix))
    }
}

lazy_static! {
    static ref SYNTAXES: HashMap<&'static [u8], &'static [u8]> = {
        let mut m = HashMap::new();

        m.insert(b"re".as_ref(), b"relre:".as_ref());
        m.insert(b"regexp".as_ref(), b"relre:".as_ref());
        m.insert(b"glob".as_ref(), b"relglob:".as_ref());
        m.insert(b"rootglob".as_ref(), b"rootglob:".as_ref());
        m.insert(b"include".as_ref(), b"include".as_ref());
        m.insert(b"subinclude".as_ref(), b"subinclude".as_ref());
        m
    };
}

pub type PatternTuple = (Vec<u8>, LineNumber, Vec<u8>);
type WarningTuple = (String, String);

pub fn parse_pattern_file_contents(
    lines: &[u8],
    file_path: &[u8],
    warn: bool,
) -> (Vec<PatternTuple>, Vec<WarningTuple>) {
    let comment_regex = Regex::new(r"((?:^|[^\\])(?:\\\\)*)#.*").unwrap();
    let mut inputs: Vec<PatternTuple> = vec![];
    let mut warnings: Vec<WarningTuple> = vec![];

    let mut current_syntax = b"relre:".as_ref();

    for (line_number, mut line) in lines.split(|c| *c == b'\n').enumerate() {
        let line_number = line_number + 1;

        if line.contains(&('#' as u8)) {
            if let Some(cap) = comment_regex.captures(line) {
                line = &line[..cap.get(1).unwrap().end()]
            }
            let mut line = line.to_owned();
            replace_slice(&mut line, br"\#", b"#");
        }

        let mut line = line.trim_end();

        if line.is_empty() {
            continue;
        }

        if line.starts_with(b"syntax:") {
            let syntax = line[b"syntax:".len()..].trim();

            if let Some(rel_syntax) = SYNTAXES.get(syntax) {
                current_syntax = rel_syntax;
            } else if warn {
                warnings.push((
                    String::from_utf8_lossy(file_path).to_string(),
                    String::from_utf8_lossy(syntax).to_string(),
                ));
            }
            continue;
        }

        let mut line_syntax: &[u8] = &current_syntax;

        for (s, rels) in SYNTAXES.iter() {
            if line.starts_with(rels) {
                line_syntax = rels;
                line = &line[rels.len()..];
                break;
            } else if line.starts_with(&[s, b":".as_ref()].concat()) {
                line_syntax = rels;
                line = &line[s.len() + 1..];
                break;
            }
        }

        inputs.push((
            [line_syntax, line].concat(),
            line_number,
            line.to_owned(),
        ));
    }
    (inputs, warnings)
}

pub fn read_pattern_file(
    file_path: &[u8],
    warn: bool,
) -> Result<(Vec<PatternTuple>, Vec<WarningTuple>), PatternFileError> {
    let mut f = File::open(get_path_from_bytes(file_path))?;
    let mut contents = Vec::new();

    f.read_to_end(&mut contents)?;

    Ok(parse_pattern_file_contents(&contents, file_path, warn))
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn escape_pattern_test() {
        let untouched = br#"!"%',/0123456789:;<=>@ABCDEFGHIJKLMNOPQRSTUVWXYZ_`abcdefghijklmnopqrstuvwxyz"#;
        assert_eq!(escape_pattern(untouched), untouched.to_vec());
        // All escape codes
        assert_eq!(
            escape_pattern(br#"()[]{}?*+-|^$\\.&~# \t\n\r\v\f"#),
            br#"\(\)\[\]\{\}\?\*\+\-\|\^\$\\\\\.\&\~\#\ \\t\\n\\r\\v\\f"#
                .to_vec()
        );
    }

    #[test]
    fn glob_test() {
        assert_eq!(glob_to_re(br#"?"#), br#"."#);
        assert_eq!(glob_to_re(br#"*"#), br#"[^/]*"#);
        assert_eq!(glob_to_re(br#"**"#), br#".*"#);
        assert_eq!(glob_to_re(br#"**/a"#), br#"(?:.*/)?a"#);
        assert_eq!(glob_to_re(br#"a/**/b"#), br#"a/(?:.*/)?b"#);
        assert_eq!(glob_to_re(br#"[a*?!^][^b][!c]"#), br#"[a*?!^][\^b][^c]"#);
        assert_eq!(glob_to_re(br#"{a,b}"#), br#"(?:a|b)"#);
        assert_eq!(glob_to_re(br#".\*\?"#), br#"\.\*\?"#);
    }

    #[test]
    fn test_parse_pattern_file_contents() {
        let lines = b"syntax: glob\n*.elc";

        assert_eq!(
            vec![(b"relglob:*.elc".to_vec(), 2, b"*.elc".to_vec())],
            parse_pattern_file_contents(lines, b"file_path", false).0,
        );

        let lines = b"syntax: include\nsyntax: glob";

        assert_eq!(
            parse_pattern_file_contents(lines, b"file_path", false).0,
            vec![]
        );
        let lines = b"glob:**.o";
        assert_eq!(
            parse_pattern_file_contents(lines, b"file_path", false).0,
            vec![(b"relglob:**.o".to_vec(), 1, b"**.o".to_vec())]
        );
    }

    #[test]
    fn test_build_single_regex_shortcut() {
        assert_eq!(
            br"(?:/|$)".to_vec(),
            build_single_regex(b"rootglob", b"", b"").unwrap()
        );
        assert_eq!(
            br"whatever(?:/|$)".to_vec(),
            build_single_regex(b"rootglob", b"whatever", b"").unwrap()
        );
        assert_eq!(
            br"[^/]*\.o".to_vec(),
            build_single_regex(b"rootglob", b"*.o", b"").unwrap()
        );
    }
}