ApplyAggregators resolves the `in` keyword in the query, taking values from one statement result than setting it on target statement result.

ApplyFilters returns a version of the already resolved Resources only with the fields defined by the `only` clause.

ApplyHidden returns a version of the already resolved Resources removing the statement results with the `hidden` clause.

NewEvaluator constructs an instance of the restQL interpreter.

ResolveVariables returns a restQL query with all variables resolved to values present in the client body, query parameters or headers, in this specific order.

ErrMapping is returned by Evaluator when the asked query references a non existing mapping.

ErrParser is returned by Evaluator when the asked query has invalid syntax.

ErrTimeout is returned by Evaluator when the query execution time exceeds the maximum time defined in configuration.

ErrValidation is returned by Evaluator when the query execution request contains invalid information.• Namespace: is an empty string or is not present• QueryRevisions name: is an empty string or is not present• Revision: is not a positive integer• Tenant: is an empty string or is not present.

Evaluator is the interpreter of the restQL language.

MappingsReader is an interface implemented by types that can fetch a collection of mapping for the given tenant.

QueryReader is an interface implemented by types that can fetch a query for the given identification (namespace, id, revision).