Class BuildingEvaluator

java.lang.Object

ca.marcusdunn.jsonlens.path.evaluator.BuildingEvaluator

public final class BuildingEvaluator
extends Object

An evaluator with building function extensions. It accepts only models that implement both JsonModel and JsonFactory.

JsonPathEvaluator.withFunctions(List, List) makes a building evaluator. It works as a JsonPathEvaluator, but the compiler rejects a read-only model:

JsonPathParser parser = JsonPathParser.withFunctions(List.of(Upper.SIGNATURE)).orElse(null);
BuildingEvaluator evaluator =
        JsonPathEvaluator.withFunctions(List.of(), List.of(new Upper())).orElse(null);

JsonPathQuery query = parser.parse("$[?upper(@) == upper('abc')]").orElse(null);
// JacksonJsonModel implements JsonModel and JsonFactory. A read-only model does not compile here.
List<Node<JsonNode>> nodes = evaluator.evaluate(query, root, JacksonJsonModel.INSTANCE).orElse(List.of());
// nodes: the paths $[0] and $[1]

A building evaluator is immutable and safe for use by more than one thread.

Method Summary

Modifier and Type	Method	Description
<N, M extends JsonModel<N> & JsonFactory<N>> Result<List<Node<N>>, EvaluationError>	evaluate(JsonPathQuery query, N root, M model)	Applies a query to a JSON value.
List<FunctionSignature>	functions()	Returns the signatures of the functions that this evaluator has.
JsonPathEvaluator.Limits	limits()	Returns the limits of this evaluator.
BuildingEvaluator	withLimits(JsonPathEvaluator.Limits limits)	Returns an evaluator with the same functions and other limits.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

withLimits

public BuildingEvaluator withLimits(JsonPathEvaluator.Limits limits)

Returns an evaluator with the same functions and other limits.

Parameters:

limits - the limits

Returns:

the evaluator

limits

public JsonPathEvaluator.Limits limits()

Returns the limits of this evaluator.

Returns:

the limits

functions

public List<FunctionSignature> functions()

Returns the signatures of the functions that this evaluator has.

Returns:

the signatures, the standard functions first

evaluate

public <N, M extends JsonModel<N> & JsonFactory<N>>
Result<List<Node<N>>, EvaluationError> evaluate(JsonPathQuery query,
 N root,
 M model)

Applies a query to a JSON value. See JsonPathEvaluator.evaluate(JsonPathQuery, Object, JsonModel).

Type Parameters:

N - the node type

M - the type of the model

Parameters:

query - the query

root - the query argument: the root node value

model - the model for the node type, which can also build nodes

Returns:

the nodelist, or an error