Parser rejects boolean comparison after `COUNT(DISTINCT ...)` during projection

[prrao87]

The Cypher parser fails when a boolean comparison is applied to an aggregate in RETURN.

Version

Tested on lance-graph 0.5.0 (Python).

Repro

import pyarrow as pa
from lance_graph import CypherQuery, GraphConfig


def build_graph() -> tuple[GraphConfig, dict[str, pa.Table]]:
    cfg = (
        GraphConfig.builder()
        .with_node_label("Person", "id")
        .with_node_label("Post", "id")
        .with_relationship("likePost", "src", "dst")
        .build()
    )

    datasets: dict[str, pa.Table] = {
        "Person": pa.table(
            {"id": [1], "firstname": ["Bill"], "lastname": ["Moore"]}
        ),
        "Post": pa.table({"id": [1]}),
        "likePost": pa.table({"src": [1], "dst": [1]}),
    }
    return cfg, datasets


def execute(query: str, cfg: GraphConfig, datasets: dict[str, pa.Table]):
    cypher = CypherQuery(query)
    return cypher.with_config(cfg).execute(datasets)


def main() -> None:
    cfg, datasets = build_graph()
    q1 = """
        MATCH (p:Post)<-[:likePost]-(p2:Person)
        WHERE p2.firstname = "Bill" AND p2.lastname = "Moore"
          AND p.id = 1
        RETURN COUNT(DISTINCT p.id) AS liked
    """
    q2 = """
        MATCH (p:Post)<-[:likePost]-(p2:Person)
        WHERE p2.firstname = "Bill" AND p2.lastname = "Moore"
          AND p.id = 2
        RETURN COUNT(DISTINCT p.id) > 0 AS liked
    """

    print("Running query without comparison:")
    print(execute(q1, cfg, datasets))

    print("\nRunning query with comparison (expected to fail):")
    try:
        print(execute(q2, cfg, datasets))
    except Exception as exc:  # noqa: BLE001 - minimal repro script
        print(f"ERROR: {exc}")


if __name__ == "__main__":
    main()

This gives:

❯ uv run repro_count_distinct_bool.py
Running query without comparison:
pyarrow.Table
liked: int64 not null
----
liked: [[1]]

Running query with comparison (expected to fail):
ERROR: Cypher parse error at position 170: Unexpected input after query: > 0 AS liked

Expected

The second query should return a boolean TRUE or FALSE based on the condition it's checking for.