Function parse_match_clauses

nodedb/src/engine/graph/pattern/compiler/mod.rs:122–161

Parse MATCH and OPTIONAL MATCH clauses from the pattern section.

(section: &str)

/// Parse MATCH and OPTIONAL MATCH clauses from the pattern section.
pub(super) fn parse_match_clauses(section: &str) -> crate::Result<Vec<MatchClause>> {
    let mut clauses = Vec::new();
    let upper = section.to_uppercase();

    let mut pos = 0;
    while pos < section.len() {
        let remaining_upper = &upper[pos..];
        let remaining = &section[pos..];

        let (optional, match_start) = if remaining_upper.trim_start().starts_with("OPTIONAL MATCH")
        {
            let ws = remaining.len() - remaining.trim_start().len();
            (true, pos + ws + 14)
        } else if remaining_upper.trim_start().starts_with("MATCH") {
            let ws = remaining.len() - remaining.trim_start().len();
            (false, pos + ws + 5)
        } else {
            break;
        };

        let rest_upper = &upper[match_start..];
        let next_match = find_next_match_keyword(rest_upper)
            .map(|offset| match_start + offset)
            .unwrap_or(section.len());

        let pattern_text = section[match_start..next_match].trim();
        let patterns = parse_pattern_chains(pattern_text)?;

        clauses.push(MatchClause { patterns, optional });
        pos = next_match;
    }

    if clauses.is_empty() {
        return Err(crate::Error::BadRequest {
            detail: "no MATCH clause found".to_string(),
        });
    }

    Ok(clauses)
}

/// Parse comma-separated pattern chains.
fn parse_pattern_chains(text: &str) -> crate::Result<Vec<PatternChain>> {