@jahed/sparql-engine/dist/optimizer/optimizer.js

SPARQL query engine for servers and web browsers.

import PlanVisitor from "./plan-visitor.js";
import UnionMerge from "./visitors/union-merge.js";
/**
 * An Optimizer applies a set of optimization rules, implemented using subclasses of {@link PlanVisitor}.
 */
export default class Optimizer {
    _visitors;
    constructor() {
        this._visitors = [];
    }
    /**
     * Get an optimizer configured with the default optimization rules
     * @return A new Optimizer pre-configured with default rules
     */
    static getDefault() {
        const opt = new Optimizer();
        opt.addVisitor(new UnionMerge());
        return opt;
    }
    /**
     * Register a new visitor, which implements an optimization rule.
     * @param visitor - Visitor
     */
    addVisitor(visitor) {
        this._visitors.push(visitor);
    }
    /**
     * Optimize a SPARQL query expression tree, by applying the set of rules.
     * @param  plan - SPARQL query expression tree to iptimize
     * @return Optimized SPARQL query expression tree
     */
    optimize(plan) {
        return this._visitors.reduce((current, v) => v.visit(current), plan);
    }
}
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