Incremunica user tools

A collection of functions to help use incremunica.

Install

$ yarn add @incremunica/user-tools

Usage

BindingsTools

The isAddition function checks if a binding is an addition. It returns true if the passed bindings are an addition, false otherwise.

import { isAddition } from '@incremunica/user-tools';
import { KeysBindings } from '@incremunica/context-entries';
import { BindingsFactory } from '@comunica/utils-bindings-factory';

export const BF = new BindingsFactory();

const bindings1 = BF.fromRecord({
  s: DF.namedNode('http://ex.org/s'),
});
const bindings2 = BF.fromRecord({
  s: DF.namedNode('http://ex.org/s'),
}).setContextEntry(KeysBindings.isAddition, true);
const bindings3 = BF.fromRecord({
  s: DF.namedNode('http://ex.org/s'),
}).setContextEntry(KeysBindings.isAddition, false);

console.log(isAddition(bindings1)); // true
console.log(isAddition(bindings2)); // true
console.log(isAddition(bindings3)); // false

The getBindingsIndex function can be used in case the query uses an ORDER BY clause. The function returns the index of the bindings in the result set and -1 if there is no index.

import { getBindingsIndex } from '@incremunica/user-tools';
import { KeysBindings } from '@incremunica/context-entries';
import { BindingsFactory } from '@comunica/utils-bindings-factory';

export const BF = new BindingsFactory();

const bindings1 = BF.fromRecord({
  s: DF.namedNode('http://ex.org/s'),
});
const bindings2 = BF.fromRecord({
  s: DF.namedNode('http://ex.org/s'),
}).setContextEntry(KeysBindings.order, {index: 0});

console.log(getBindingsIndex(bindings1)); // -1
console.log(getBindingsIndex(bindings2)); // 0

DeferredEvaluationTools

The DeferredEvaluation class can be used to trigger a deferred evaluation of a query engine.

import {DeferredEvaluation} from '@incremunica/user-tools';
import {QueryEngine} from "@incremunica/query-sparql-incremental";

const deferredEvaluation = new DeferredEvaluation();
const queryEngine = new QueryEngine();
const bindingsStream = queryEngine.queryBindings("SELECT * WHERE { ?s ?p ?o }", {
    sources: [ "https://www.rubensworks.net/" ],
    deferredEvaluationTrigger: deferredEvaluation.events
});

// Trigger the deferred evaluation
deferredEvaluation.triggerUpdate();

SourcesTools

createSourcesStreamFromBindingsStream can be used to create a sources stream from a bindings stream.

import {createSourcesStreamFromBindingsStream} from '@incremunica/user-tools';
import {QueryEngine} from "@incremunica/query-sparql-incremental";

const queryEngine = new QueryEngine();
const bindingsStream1 = queryEngine.queryBindings("SELECT * WHERE { ?s ?p ?o }", {
    sources: [ "https://www.rubensworks.net/" ],
});
const bindingsStream2 = queryEngine.queryBindings("SELECT * WHERE { ?s ?p ?o }", {
  sources: [ createSourcesStreamFromBindingsStream(bindingsStream1, ["s"]) ],
});

QuerySourceIterator is a helper class to help build a query sources stream from different locations to pass to the query engine.

import {QuerySourceIterator} from '@incremunica/user-tools';
import {QueryEngine} from "@incremunica/query-sparql-incremental";

const querySourceIterator = new QuerySourceIterator({
  seedSources: ["https://www.rubensworks.net/"],
  distinct: true
});
const queryEngine = new QueryEngine();
const bindingsStream = queryEngine.queryBindings("SELECT * WHERE { ?s ?p ?o }", {
  sources: [querySourceIterator],
});

querySourceIterator.addSource("https://ruben.verborgh.org/profile/"); // Add a source
querySourceIterator.removeSource("https://www.rubensworks.net/"); // Remove a source
querySourceIterator.addBindingsStream(anotherBindingsStream); // Add a bindings stream
querySourceIterator.addBindingsStream(bindingsStream, ["s"]); // Add results from the same bindingsStream