Module unnest_sql 

E5.2 — LATERAL / UNNEST SQL pre-processing.

DataFusion 53 supports UNNEST inside SELECT and FROM clauses for fixed-size arrays. This module provides:

1. Detection: identify UNNEST calls in SQL text before passing to DataFusion.
2. Rewriter: normalise the common LATERAL UNNEST idiom to a canonical form that DataFusion can plan (CROSS JOIN UNNEST).
3. NodeOp builder: return a NodeOp::Unnest descriptor so the Krishiv plan layer can record the unnest operator.

Functions

build_unnest_op

Build a NodeOp::Unnest descriptor.

contains_lateral

Returns true if sql contains a LATERAL keyword (case-insensitive).

contains_unnest

Returns true if sql contains an UNNEST call (case-insensitive).

rewrite_lateral_unnest

Rewrite LATERAL UNNEST(...) idioms to a form DataFusion understands.