Module nested 

Nested query support for backward chaining

This module implements nested/subqueries in backward chaining queries. Subqueries allow using the results of one query as input to another query.

Examples

// Find grandparents: people who are parents of parents
let results = engine.query(
    "grandparent(?x, ?z) WHERE
        parent(?x, ?y) AND
        (parent(?y, ?z) WHERE child(?z, ?y))",
    &mut facts
)?;

// Find high-value customers: VIPs or those with large purchases
let results = engine.query(
    "high_value(?customer) WHERE
        (vip(?customer) OR
         (purchase(?customer, ?item, ?amount) WHERE ?amount > 1000))",
    &mut facts
)?;

Structs

NestedQuery

Represents a nested query (subquery) within a larger query

NestedQueryEvaluator

Evaluator for nested queries

NestedQueryParser

Parser for nested queries

NestedQueryResult

Result of evaluating a nested query

NestedQueryStats

Statistics for nested query evaluation

Query

Represents a query that may contain nested subqueries