Function intercept_fts_function

nodedb-sql/src/resolver/expr/functions.rs:98–131

Intercept PG FTS surface functions and lower them to `pg_*` internal function-call `SqlExpr` nodes. Returns `Ok(None)` for non-FTS names. `ts_rank_cd` is rejected with `SqlError::Unsupported` as per the approved design.

(
    name: &str,
    func: &ast::Function,
    depth: &mut usize,
)

/// `ts_rank_cd` is rejected with `SqlError::Unsupported` as per the
/// approved design.
fn intercept_fts_function(
    name: &str,
    func: &ast::Function,
    depth: &mut usize,
) -> Result<Option<SqlExpr>> {
    use crate::functions::fts_ops::pg_fts_funcs;

    let args = collect_function_args(func, depth)?;
    match name {
        "to_tsvector" => Ok(Some(SqlExpr::Function {
            name: "pg_to_tsvector".into(),
            args,
            distinct: false,
        })),
        "to_tsquery" => Ok(Some(pg_fts_funcs::lower_pg_to_tsquery(args))),
        "plainto_tsquery" => Ok(Some(pg_fts_funcs::lower_pg_plainto_tsquery(args))),
        "phraseto_tsquery" => Ok(Some(pg_fts_funcs::lower_phraseto_tsquery(args))),
        "websearch_to_tsquery" => Ok(Some(pg_fts_funcs::lower_pg_websearch_to_tsquery(args))),
        "ts_rank" => Ok(Some(SqlExpr::Function {
            name: "pg_ts_rank".into(),
            args,
            distinct: false,
        })),
        "ts_rank_cd" => Err(SqlError::Unsupported {
            detail: "ts_rank_cd is not supported; use ts_rank or bm25_score instead".into(),
        }),
        "ts_headline" => Ok(Some(SqlExpr::Function {
            name: "pg_ts_headline".into(),
            args,
            distinct: false,
        })),
        _ => Ok(None),
    }
}

/// Collect function call arguments, converting each `Expr` to `SqlExpr`.
fn collect_function_args(func: &ast::Function, depth: &mut usize) -> Result<Vec<SqlExpr>> {