--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/rust/hg-core/src/filepatterns.rs	Wed Apr 24 11:34:09 2019 +0200
@@ -0,0 +1,345 @@
+use crate::{LineNumber, PatternError, PatternFileError};
+use regex::Regex;
+use std::collections::HashMap;
+use std::fs::File;
+use std::io::Read;
+use std::vec::Vec;
+
+lazy_static! {
+    static ref reescape: 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(&reescape[*c as usize])
+            }
+            _ => res.extend(&reescape[*c as usize]),
+        }
+    }
+    res
+}
+
+fn escape_pattern(pattern: &[u8]) -> Vec<u8> {
+    pattern
+        .iter()
+        .flat_map(|c| reescape[*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: &str,
+    pat: &[u8],
+    globsuffix: &[u8],
+) -> Result<Vec<u8>, PatternError> {
+    let enum_kind = parse_pattern_syntax(kind.as_bytes())?;
+    if enum_kind == PatternSyntax::RootGlob
+        && pat.iter().all(|b| GLOB_SPECIAL_CHARACTERS.contains(b))
+    {
+        Ok(pat.to_vec())
+    } else {
+        Ok(_build_single_regex(enum_kind, pat, globsuffix))
+    }
+}
+
+lazy_static! {
+    static ref SYNTAXES: HashMap<&'static str, &'static str> = {
+        let mut m = HashMap::new();
+
+        m.insert("re", "relre:");
+        m.insert("regexp", "relre:");
+        m.insert("glob", "relglob:");
+        m.insert("rootglob", "rootglob:");
+        m.insert("include", "include");
+        m.insert("subinclude", "subinclude");
+        m
+    };
+}
+
+pub type PatternTuple = (String, LineNumber, String);
+type WarningTuple = (String, String);
+
+pub fn parse_pattern_file_contents(
+    lines: &str,
+    file_path: &str,
+    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 = "relre:";
+
+    let mut line = String::new();
+    for (line_number, line_str) in lines.split('\n').enumerate() {
+        let line_number = line_number + 1;
+        line.replace_range(.., line_str);
+
+        if line.contains('#') {
+            if let Some(cap) = comment_regex.captures(line.clone().as_ref()) {
+                line = line[..cap.get(1).unwrap().end()].to_string()
+            }
+            line = line.replace(r"\#", "#");
+        }
+
+        let mut line = line.trim_end();
+
+        if line.is_empty() {
+            continue;
+        }
+
+        if line.starts_with("syntax:") {
+            let syntax = line["syntax:".len()..].trim();
+
+            if let Some(rel_syntax) = SYNTAXES.get(syntax) {
+                current_syntax = rel_syntax;
+            } else if warn {
+                warnings.push((file_path.to_string(), syntax.to_string()));
+            }
+            continue;
+        }
+
+        let mut line_syntax: &str = &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(&format!("{}:", s)) {
+                line_syntax = rels;
+                line = &line[s.len() + 1..];
+                break;
+            }
+        }
+
+        inputs.push((
+            format!("{}{}", line_syntax, line),
+            line_number,
+            line.to_string(),
+        ));
+    }
+    (inputs, warnings)
+}
+
+pub fn read_pattern_file(
+    file_path: String,
+    warn: bool,
+) -> Result<(Vec<PatternTuple>, Vec<WarningTuple>), PatternFileError> {
+    let mut f = File::open(&file_path)?;
+    let mut contents = String::new();
+
+    f.read_to_string(&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 = "syntax: glob\n*.elc";
+
+        assert_eq!(
+            vec![("relglob:*.elc".to_string(), 2, "*.elc".to_string())],
+            parse_pattern_file_contents(lines, "file_path", false).0,
+        );
+
+        let lines = "syntax: include\nsyntax: glob";
+
+        assert_eq!(
+            parse_pattern_file_contents(lines, "file_path", false).0,
+            vec![]
+        );
+    }
+}