@n1ru4l/graphql-live-query-patch/esm/createLiveQueryPatchGenerator.js

Shared logic for building live query patch implementations.

import { Repeater } from "@repeaterjs/repeater";
/**
 * Symbol that indicates that there is no diff between the previous and current state and thus no patch must be sent to the client.
 * This value should be returned from GeneratePatchFunction.
 */
export const noDiffSymbol = Symbol("noDiffSymbol");
export const createLiveQueryPatchGenerator = (generatePatch) => (source) => new Repeater(async (push, stop) => {
    var _a, _b;
    const iterator = source[Symbol.asyncIterator]();
    stop.then(() => { var _a; return (_a = iterator.return) === null || _a === void 0 ? void 0 : _a.call(iterator); });
    let previousValue = null;
    let revision = 1;
    let next;
    while ((next = await iterator.next()).done === false) {
        // if it is not live we simply forward everything :)
        if (!next.value.isLive) {
            await push(next.value);
            continue;
        }
        const valueToPublish = {};
        if (previousValue) {
            const currentValue = (_a = next.value.data) !== null && _a !== void 0 ? _a : {};
            const patch = generatePatch(previousValue, currentValue);
            previousValue = currentValue;
            if (patch === noDiffSymbol) {
                continue;
            }
            valueToPublish.patch = patch;
            revision++;
        }
        else {
            previousValue = (_b = next.value.data) !== null && _b !== void 0 ? _b : {};
            if ("data" in next.value) {
                valueToPublish.data = previousValue;
            }
        }
        if ("errors" in next.value) {
            valueToPublish.errors = next.value.errors;
        }
        if ("extensions" in next.value) {
            valueToPublish.extensions = next.value.extensions;
        }
        valueToPublish.revision = revision;
        await push(valueToPublish);
    }
    stop();
});