Function preprocess

nodedb-sql/src/parser/preprocess/pipeline.rs:42–136

Pre-process a SQL string, rewriting NodeDB-specific syntax. Returns `Ok(None)` if no rewriting was needed. Temporal clause parse errors bubble up as `SqlError::Parse` so they surface to the caller identically to sqlparser errors.

(sql: &str)

/// errors bubble up as `SqlError::Parse` so they surface to the caller
/// identically to sqlparser errors.
pub fn preprocess(sql: &str) -> Result<Option<PreprocessedSql>, SqlError> {
    let trimmed = sql.trim();

    // Extract temporal clauses first — they can appear in both SELECT and
    // INSERT...SELECT, and stripping them before the UPSERT/object-literal
    // rewrites keeps those rewriters pattern-free of NodeDB extensions.
    let (temporal_sql, temporal) =
        match extract_temporal(trimmed).map_err(|e| SqlError::Parse { detail: e.0 })? {
            Some(ex) => (ex.sql, ex.temporal),
            None => (trimmed.to_string(), TemporalScope::default()),
        };
    let any_temporal = temporal != TemporalScope::default();

    // Rewrite `SEARCH <coll> USING VECTOR(...)` to canonical
    // `SELECT * FROM <coll> ORDER BY vector_distance(...) LIMIT k` before any
    // first-word dispatch — the rewritten form re-enters the rest of the
    // pipeline as a plain SELECT.
    let (temporal_sql, search_vector_rewritten) =
        match try_rewrite_search_using_vector(&temporal_sql) {
            Some(rewritten) => (rewritten, true),
            None => (temporal_sql, false),
        };

    let first_word = first_sql_word(&temporal_sql)
        .map(|w| w.to_uppercase())
        .unwrap_or_default();
    let is_upsert = first_word == "UPSERT";

    if is_upsert {
        let rewritten = format!("INSERT INTO {}", &temporal_sql["UPSERT INTO ".len()..]);
        if let Some(result) = try_rewrite_object_literal(&rewritten) {
            return Ok(Some(PreprocessedSql {
                sql: result,
                is_upsert: true,
                temporal,
            }));
        }
        return Ok(Some(PreprocessedSql {
            sql: rewritten,
            is_upsert: true,
            temporal,
        }));
    }

    if first_word == "INSERT"
        && let Some(result) = try_rewrite_object_literal(&temporal_sql)
    {
        return Ok(Some(PreprocessedSql {
            sql: result,
            is_upsert: false,
            temporal,
        }));
    }

    let mut sql_buf = temporal_sql;
    let mut any_rewrite = any_temporal || search_vector_rewritten;

    if has_operator_outside_literals(&sql_buf, "<->")