Struct SubqueryExecutor 

pub struct SubqueryExecutor;

Executor for SPARQL subqueries

Implementations

impl SubqueryExecutor

pub fn new() -> Self

Create a new executor

pub fn execute( &self, subquery: &Subquery, outer_bindings: &[HashMap<String, String>], ) -> SubqueryResult

Execute a subquery given a set of outer bindings.

The algorithm:

1. For each triple pattern in the inner WHERE, generate candidate bindings by matching against the outer bindings (simulated evaluation).
2. If the subquery is correlated, inject the outer binding into every candidate.
3. Apply FILTER expressions (simple equality checks on bound variables).
4. Project to the SELECT variables.
5. Apply DISTINCT, OFFSET, LIMIT.

pub fn project( bindings: Vec<HashMap<String, String>>, vars: &[String], ) -> Vec<HashMap<String, String>>

Project bindings to only the specified variables. If vars is empty, all variables are kept (SELECT *).

pub fn deduplicate( bindings: Vec<HashMap<String, String>>, ) -> Vec<HashMap<String, String>>

Remove duplicate bindings

pub fn apply_limit_offset( bindings: Vec<HashMap<String, String>>, limit: Option<usize>, offset: Option<usize>, ) -> Vec<HashMap<String, String>>

Apply LIMIT and OFFSET to a binding sequence

pub fn variables_used(query: &SelectQuery) -> Vec<String>

Return all variable names used in the query’s WHERE clause

pub fn is_correlated(subquery: &Subquery) -> bool

Return true if the subquery references any outer variables in its WHERE clause

Trait Implementations

impl Default for SubqueryExecutor

fn default() -> Self

Returns the “default value” for a type.