Module graph_table 

SQL/PGQ’s GRAPH_TABLE ( … ), rewritten before sqlparser sees it (#296).

sqlparser has no SQL/PGQ grammar, and forking it is ruled out. So, as DuckPGQ puts a grammar extension in front of DuckDB’s parser, Ursa rewrites each GRAPH_TABLE ( body ) (or GRAPH TABLE ( body )) in a statement’s text into an ordinary table function call, graph_table('body'), before the statement is parsed. The engine’s relation planner parses the body (the graph’s name, MATCH, the pattern, WHERE and COLUMNS) and plans it.

The rewrite works on sqlparser’s own tokens, so a GRAPH_TABLE inside a string or a comment is left alone, and the matching ) is found by counting brackets over tokens, which strings and comments cannot unbalance. Text outside each GRAPH_TABLE ( … ) is kept byte for byte.

Constants

GRAPH_TABLE_FUNCTION

The table function a GRAPH_TABLE ( … ) becomes.

Functions

rewrite_graph_tables

sql with every GRAPH_TABLE ( body ) rewritten to graph_table('body'). Text that does not tokenize is returned as it is, for the parser to report.