rdf-dataset-fragmenter/lib/transform/QuadTransformerDistinct.js

Fragments an RDF dataset into multiple parts

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.QuadTransformerDistinct = void 0;
const rdf_string_1 = require("rdf-string");
/**
 * A quad transformer that wraps over another quad transformer and removes duplicates produced by the transformer.
 * Only quads that are produced by the quad transformer (and are unequal to the incoming quad) will be filtered away.
 */
class QuadTransformerDistinct {
    constructor(transformer) {
        this.transformer = transformer;
        this.passedQuads = new Set();
    }
    transform(quad, allowedComponent) {
        return this.transformer.transform(quad)
            .filter((quadOut) => {
            // Always let through quads that equal the incoming quad
            if (quadOut.equals(quad)) {
                return true;
            }
            const hash = JSON.stringify({ ...(0, rdf_string_1.quadToStringQuad)(quadOut), allowedComponent });
            if (this.passedQuads.has(hash)) {
                return false;
            }
            this.passedQuads.add(hash);
            return true;
        });
    }
    end() {
        if (this.transformer.end) {
            this.transformer.end();
        }
    }
}
exports.QuadTransformerDistinct = QuadTransformerDistinct;
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