@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, shallowEqualObjects } from "./utils.js";
function difference(array1, array2) {
  const excludeSet = new Set(array2);
  return array1.filter((x) => !excludeSet.has(x));
}
function replaceAt(array, index, value) {
  const copy = array.slice(0);
  copy[index] = value;
  return copy;
}
var QueriesObserver = class extends Subscribable {
  #client;
  #result;
  #queries;
  #options;
  #observers;
  #combinedResult;
  #lastCombine;
  #lastResult;
  #lastQueryHashes;
  #observerMatches = [];
  constructor(client, queries, options) {
    super();
    this.#client = client;
    this.#options = options;
    this.#queries = [];
    this.#observers = [];
    this.#result = [];
    this.setQueries(queries);
  }
  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) {
    this.#queries = queries;
    this.#options = options;
    if (process.env.NODE_ENV !== "production") {
      const queryHashes = queries.map(
        (query) => this.#client.defaultQueryOptions(query).queryHash
      );
      if (new Set(queryHashes).size !== queryHashes.length) {
        console.warn(
          "[QueriesObserver]: Duplicate Queries found. This might result in unexpected behavior."
        );
      }
    }
    notifyManager.batch(() => {
      const prevObservers = this.#observers;
      const newObserverMatches = this.#findMatchingObservers(this.#queries);
      newObserverMatches.forEach(
        (match) => match.observer.setOptions(match.defaultedQueryOptions)
      );
      const newObservers = newObserverMatches.map((match) => match.observer);
      const newResult = newObservers.map(
        (observer) => observer.getCurrentResult()
      );
      const hasLengthChange = prevObservers.length !== newObservers.length;
      const hasIndexChange = newObservers.some(
        (observer, index) => observer !== prevObservers[index]
      );
      const hasStructuralChange = hasLengthChange || hasIndexChange;
      const hasResultChange = hasStructuralChange ? true : newResult.some((result, index) => {
        const prev = this.#result[index];
        return !prev || !shallowEqualObjects(result, prev);
      });
      if (!hasStructuralChange && !hasResultChange) return;
      if (hasStructuralChange) {
        this.#observerMatches = newObserverMatches;
        this.#observers = newObservers;
      }
      this.#result = newResult;
      if (!this.hasListeners()) return;
      if (hasStructuralChange) {
        difference(prevObservers, newObservers).forEach((observer) => {
          observer.destroy();
        });
        difference(newObservers, prevObservers).forEach((observer) => {
          observer.subscribe((result) => {
            this.#onUpdate(observer, result);
          });
        });
      }
      this.#notify();
    });
  }
  getCurrentResult() {
    return this.#result;
  }
  getQueries() {
    return this.#observers.map((observer) => observer.getCurrentQuery());
  }
  getObservers() {
    return this.#observers;
  }
  getOptimisticResult(queries, combine) {
    const matches = this.#findMatchingObservers(queries);
    const result = matches.map(
      (match) => match.observer.getOptimisticResult(match.defaultedQueryOptions)
    );
    const queryHashes = matches.map(
      (match) => match.defaultedQueryOptions.queryHash
    );
    return [
      result,
      (r) => {
        return this.#combineResult(r ?? result, combine, queryHashes);
      },
      () => {
        return this.#trackResult(result, matches);
      }
    ];
  }
  #trackResult(result, matches) {
    return matches.map((match, index) => {
      const observerResult = result[index];
      return !match.defaultedQueryOptions.notifyOnChangeProps ? match.observer.trackResult(observerResult, (accessedProp) => {
        matches.forEach((m) => {
          m.observer.trackProp(accessedProp);
        });
      }) : observerResult;
    });
  }
  #combineResult(input, combine, queryHashes) {
    if (combine) {
      const lastHashes = this.#lastQueryHashes;
      const queryHashesChanged = queryHashes !== void 0 && lastHashes !== void 0 && (lastHashes.length !== queryHashes.length || queryHashes.some((hash, i) => hash !== lastHashes[i]));
      if (!this.#combinedResult || this.#result !== this.#lastResult || queryHashesChanged || combine !== this.#lastCombine) {
        this.#lastCombine = combine;
        this.#lastResult = this.#result;
        if (queryHashes !== void 0) {
          this.#lastQueryHashes = queryHashes;
        }
        this.#combinedResult = replaceEqualDeep(
          this.#combinedResult,
          combine(input)
        );
      }
      return this.#combinedResult;
    }
    return input;
  }
  #findMatchingObservers(queries) {
    const prevObserversMap = /* @__PURE__ */ new Map();
    this.#observers.forEach((observer) => {
      const key = observer.options.queryHash;
      if (!key) return;
      const previousObservers = prevObserversMap.get(key);
      if (previousObservers) {
        previousObservers.push(observer);
      } else {
        prevObserversMap.set(key, [observer]);
      }
    });
    const observers = [];
    queries.forEach((options) => {
      const defaultedOptions = this.#client.defaultQueryOptions(options);
      const match = prevObserversMap.get(defaultedOptions.queryHash)?.shift();
      const observer = match ?? new QueryObserver(this.#client, defaultedOptions);
      observers.push({
        defaultedQueryOptions: defaultedOptions,
        observer
      });
    });
    return observers;
  }
  #onUpdate(observer, result) {
    const index = this.#observers.indexOf(observer);
    if (index !== -1) {
      this.#result = replaceAt(this.#result, index, result);
      this.#notify();
    }
  }
  #notify() {
    if (this.hasListeners()) {
      const previousResult = this.#combinedResult;
      const newTracked = this.#trackResult(this.#result, this.#observerMatches);
      const newResult = this.#combineResult(newTracked, this.#options?.combine);
      if (previousResult !== newResult) {
        notifyManager.batch(() => {
          this.listeners.forEach((listener) => {
            listener(this.#result);
          });
        });
      }
    }
  }
};
export {
  QueriesObserver
};
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