Module expr_util 

Shared expression utilities for optimizer passes.

Provides:

• SQL fragment parsing helpers (parse_predicate, parse_expr)
• Expression rendering (render)
• Conjunct splitting and joining (split_conjuncts, join_conjuncts)
• Equi-join key extraction (equi_key)
• Column-reference collection (collect_colrefs)
• Canonical structural hashing (canonical_hash)
• Common-subexpression detection (find_common_subexprs)

Structs

ColRef

A qualified column reference extracted from an expression.

Functions

canonical_hash

Compute a canonical (order-normalised) structural hash of an Expr.

collect_colrefs

Collect all column references reachable from e.

equi_key

If e is an equi-join predicate a.x = b.y (or x = y), return the two ColRefs. Returns None for any other expression shape.

find_common_subexprs

Find common (repeated) subexpressions in e by canonical hash.

join_conjuncts

Join a list of expressions with AND.

parse_expr

Parse a standalone SQL expression (not a WHERE predicate), returning None on failure.

parse_predicate

Parse a SQL predicate string into an Expr, returning None on failure.

render

Render an Expr back to a SQL string via its Display implementation.

split_conjuncts

Split a top-level AND expression into its conjuncts (leaves of the AND tree).