Function build_subpatterns

src/expr/src/scalar/like_pattern.rs:320–361

Breaks a LIKE pattern into a chain of sub-patterns.

(pattern: &str)

/// Breaks a LIKE pattern into a chain of sub-patterns.
fn build_subpatterns(pattern: &str) -> Result<Vec<Subpattern>, EvalError> {
    let mut subpatterns = Vec::with_capacity(MAX_SUBPATTERNS);
    let mut current = Subpattern::default();
    let mut in_wildcard = true;
    let mut in_escape = false;
    for c in pattern.chars() {
        match c {
            c if !in_escape && c == DEFAULT_ESCAPE => {
                in_escape = true;
                in_wildcard = false;
            }
            '_' if !in_escape => {
                if !in_wildcard {
                    current.suffix.shrink_to_fit();
                    subpatterns.push(mem::take(&mut current));
                    in_wildcard = true;
                }
                current.consume += 1;
            }
            '%' if !in_escape => {
                if !in_wildcard {
                    current.suffix.shrink_to_fit();
                    subpatterns.push(mem::take(&mut current));
                    in_wildcard = true;
                }
                current.many = true;
            }
            c => {
                current.suffix.push(c);
                in_escape = false;
                in_wildcard = false;
            }
        }
    }
    if in_escape {
        return Err(EvalError::UnterminatedLikeEscapeSequence);
    }
    current.suffix.shrink_to_fit();
    subpatterns.push(current);
    subpatterns.shrink_to_fit();
    Ok(subpatterns)
}

/// Builds a regular expression that matches some parsed Subpatterns.
fn build_regex(subpatterns: &[Subpattern], case_insensitive: bool) -> Result<Regex, EvalError> {