grafast/dist/steps/last.js

Cutting edge GraphQL planning and execution engine

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.LastStep = void 0;
exports.last = last;
const constants_js_1 = require("../constants.js");
const step_js_1 = require("../step.js");
const connection_js_1 = require("./connection.js");
const list_js_1 = require("./list.js");
function unbatchedExecute(_extra, list) {
    return list?.[list.length - 1];
}
function optimalExecute({ indexMap, values: [values0], }) {
    return indexMap((i) => {
        const list = values0.at(i);
        return list?.[list.length - 1];
    });
}
class LastStep extends step_js_1.Step {
    static { this.$$export = {
        moduleName: "grafast",
        exportName: "LastStep",
    }; }
    constructor(parentPlan, isArray = true) {
        super();
        this.allowMultipleOptimizations = true;
        this.addDependency((0, connection_js_1.itemsOrStep)(parentPlan));
        if (isArray) {
            this.unbatchedExecute = unbatchedExecute;
            this.execute = (optimalExecute);
            this.isSyncAndSafe = true;
        }
        else {
            this.isSyncAndSafe = false;
        }
    }
    [constants_js_1.$$deepDepSkip]() {
        return this.getDepOptions(0).step;
    }
    execute({ indexMap, values: [values0], }) {
        return indexMap((i) => {
            const val = values0.at(i);
            if (val == null)
                return val;
            if (Array.isArray(val))
                return val[val.length - 1];
            // Iterable? Return the last entry
            return (async () => {
                let last = undefined;
                for await (const e of val) {
                    last = e;
                }
                return last;
            })();
        });
    }
    deduplicate(peers) {
        return peers;
    }
    optimize() {
        const parent = this.getDep(0);
        // The last of a list plan is just the last dependency of the list plan.
        if (parent instanceof list_js_1.ListStep) {
            return parent.last();
        }
        return this;
    }
}
exports.LastStep = LastStep;
/**
 * A plan that resolves to the last entry in the list returned by the given
 * plan.
 *
 * @param plan - the list plan
 * @param array - set this true if the plan represents an array (or
 * null/undefined) - i.e. it' won't be an (async) iterable - to enable greater
 * optimization
 */
function last(plan, array = true) {
    return plan.operationPlan.cacheStep(plan, "GrafastInternal:last()", array, () => new LastStep(plan, array));
}
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