@tanstack/query-core/build/modern/queriesObserver.js

The framework agnostic core that powers TanStack Query

// src/queriesObserver.ts
import { notifyManager } from "./notifyManager.js";
import { QueryObserver } from "./queryObserver.js";
import { Subscribable } from "./subscribable.js";
import { replaceEqualDeep } from "./utils.js";
function difference(array1, array2) {
  return array1.filter((x) => !array2.includes(x));
}
function replaceAt(array, index, value) {
  const copy = array.slice(0);
  copy[index] = value;
  return copy;
}
var QueriesObserver = class extends Subscribable {
  #client;
  #result;
  #queries;
  #observers;
  #options;
  #combinedResult;
  constructor(client, queries, options) {
    super();
    this.#client = client;
    this.#queries = [];
    this.#observers = [];
    this.#setResult([]);
    this.setQueries(queries, options);
  }
  #setResult(value) {
    this.#result = value;
    this.#combinedResult = this.#combineResult(value);
  }
  onSubscribe() {
    if (this.listeners.size === 1) {
      this.#observers.forEach((observer) => {
        observer.subscribe((result) => {
          this.#onUpdate(observer, result);
        });
      });
    }
  }
  onUnsubscribe() {
    if (!this.listeners.size) {
      this.destroy();
    }
  }
  destroy() {
    this.listeners = /* @__PURE__ */ new Set();
    this.#observers.forEach((observer) => {
      observer.destroy();
    });
  }
  setQueries(queries, options, notifyOptions) {
    this.#queries = queries;
    this.#options = options;
    notifyManager.batch(() => {
      const prevObservers = this.#observers;
      const newObserverMatches = this.#findMatchingObservers(this.#queries);
      newObserverMatches.forEach(
        (match) => match.observer.setOptions(match.defaultedQueryOptions, notifyOptions)
      );
      const newObservers = newObserverMatches.map((match) => match.observer);
      const newResult = newObservers.map(
        (observer) => observer.getCurrentResult()
      );
      const hasIndexChange = newObservers.some(
        (observer, index) => observer !== prevObservers[index]
      );
      if (prevObservers.length === newObservers.length && !hasIndexChange) {
        return;
      }
      this.#observers = newObservers;
      this.#setResult(newResult);
      if (!this.hasListeners()) {
        return;
      }
      difference(prevObservers, newObservers).forEach((observer) => {
        observer.destroy();
      });
      difference(newObservers, prevObservers).forEach((observer) => {
        observer.subscribe((result) => {
          this.#onUpdate(observer, result);
        });
      });
      this.#notify();
    });
  }
  getCurrentResult() {
    return this.#combinedResult;
  }
  getQueries() {
    return this.#observers.map((observer) => observer.getCurrentQuery());
  }
  getObservers() {
    return this.#observers;
  }
  getOptimisticResult(queries) {
    const matches = this.#findMatchingObservers(queries);
    const result = matches.map(
      (match) => match.observer.getOptimisticResult(match.defaultedQueryOptions)
    );
    return [
      result,
      (r) => {
        return this.#combineResult(r ?? result);
      },
      () => {
        return matches.map((match, index) => {
          const observerResult = result[index];
          return !match.defaultedQueryOptions.notifyOnChangeProps ? match.observer.trackResult(observerResult) : observerResult;
        });
      }
    ];
  }
  #combineResult(input) {
    const combine = this.#options?.combine;
    if (combine) {
      return replaceEqualDeep(this.#combinedResult, combine(input));
    }
    return input;
  }
  #findMatchingObservers(queries) {
    const prevObservers = this.#observers;
    const prevObserversMap = new Map(
      prevObservers.map((observer) => [observer.options.queryHash, observer])
    );
    const defaultedQueryOptions = queries.map(
      (options) => this.#client.defaultQueryOptions(options)
    );
    const matchingObservers = defaultedQueryOptions.flatMap((defaultedOptions) => {
      const match = prevObserversMap.get(defaultedOptions.queryHash);
      if (match != null) {
        return [{ defaultedQueryOptions: defaultedOptions, observer: match }];
      }
      return [];
    });
    const matchedQueryHashes = new Set(
      matchingObservers.map((match) => match.defaultedQueryOptions.queryHash)
    );
    const unmatchedQueries = defaultedQueryOptions.filter(
      (defaultedOptions) => !matchedQueryHashes.has(defaultedOptions.queryHash)
    );
    const getObserver = (options) => {
      const defaultedOptions = this.#client.defaultQueryOptions(options);
      const currentObserver = this.#observers.find(
        (o) => o.options.queryHash === defaultedOptions.queryHash
      );
      return currentObserver ?? new QueryObserver(this.#client, defaultedOptions);
    };
    const newOrReusedObservers = unmatchedQueries.map((options) => {
      return {
        defaultedQueryOptions: options,
        observer: getObserver(options)
      };
    });
    const sortMatchesByOrderOfQueries = (a, b) => defaultedQueryOptions.indexOf(a.defaultedQueryOptions) - defaultedQueryOptions.indexOf(b.defaultedQueryOptions);
    return matchingObservers.concat(newOrReusedObservers).sort(sortMatchesByOrderOfQueries);
  }
  #onUpdate(observer, result) {
    const index = this.#observers.indexOf(observer);
    if (index !== -1) {
      this.#setResult(replaceAt(this.#result, index, result));
      this.#notify();
    }
  }
  #notify() {
    notifyManager.batch(() => {
      this.listeners.forEach((listener) => {
        listener(this.#result);
      });
    });
  }
};
export {
  QueriesObserver
};
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