vscroll/dist/esm5/classes/buffer/defaultSize.js

Virtual scroll engine

import { __read, __spreadArray } from "tslib";
import { SizeStrategy } from '../../inputs/index';
var SizesRecalculation = /** @class */ (function () {
  function SizesRecalculation() {
    this.reset();
  }
  SizesRecalculation.prototype.reset = function () {
    this.newItems = [];
    this.oldItems = [];
    this.removed = [];
  };
  return SizesRecalculation;
}());
export { SizesRecalculation };
var DefaultSize = /** @class */ (function () {
  function DefaultSize(itemSize, sizeStrategy) {
    this.itemSize = itemSize;
    this.sizeStrategy = sizeStrategy;
    this.sizeMap = new Map();
    this.recalculation = new SizesRecalculation();
  }
  DefaultSize.prototype.reset = function (force) {
    if (force) {
      this.constantSize = this.itemSize;
      this.frequentSize = this.itemSize;
      this.averageSize = this.itemSize;
      this.averageSizeFloat = this.itemSize;
      this.sizeMap.clear();
    }
    this.recalculation.reset();
  };
  DefaultSize.prototype.get = function () {
    switch (this.sizeStrategy) {
      case SizeStrategy.Average:
        return this.averageSize;
      case SizeStrategy.Frequent:
        return this.frequentSize;
      default:
        return this.constantSize;
    }
  };
  DefaultSize.prototype.recalculateAverageSize = function (cacheSize) {
    var _a = this.recalculation, oldItems = _a.oldItems, newItems = _a.newItems, removed = _a.removed;
    if (oldItems.length) {
      var oldSize = oldItems.reduce(function (acc, item) { return acc + item.size; }, 0);
      var newSize = oldItems.reduce(function (acc, item) { return acc + item.newSize; }, 0);
      var averageSize = this.averageSizeFloat || 0;
      this.averageSizeFloat = averageSize - (oldSize - newSize) / (cacheSize - newItems.length);
    }
    if (newItems.length) {
      var newSize = newItems.reduce(function (acc, item) { return acc + item.size; }, 0);
      var averageSize = this.averageSizeFloat || 0;
      this.averageSizeFloat = ((cacheSize - newItems.length) * averageSize + newSize) / cacheSize;
    }
    if (removed.length) {
      var removedSize = removed.reduce(function (acc, item) { return acc + item.size; }, 0);
      var averageSize = this.averageSizeFloat || 0;
      this.averageSizeFloat =
        ((cacheSize + removed.length) * averageSize - removedSize) / cacheSize;
    }
    this.averageSize = Math.round(this.averageSizeFloat);
  };
  DefaultSize.prototype.recalculateFrequentSize = function () {
    var _this = this;
    var _a = this.recalculation, oldItems = _a.oldItems, newItems = _a.newItems, removed = _a.removed;
    var oldFrequentSizeCount = this.sizeMap.get(this.frequentSize);
    if (newItems.length) {
      newItems.forEach(function (_a) {
        var size = _a.size;
        return _this.sizeMap.set(size, (_this.sizeMap.get(size) || 0) + 1);
      });
    }
    if (oldItems.length) {
      oldItems.forEach(function (_a) {
        var size = _a.size;
        return _this.sizeMap.set(size, Math.max((_this.sizeMap.get(size) || 0) - 1, 0));
      });
      oldItems.forEach(function (_a) {
        var s = _a.newSize;
        return _this.sizeMap.set(s, (_this.sizeMap.get(s) || 0) + 1);
      });
    }
    if (removed.length) {
      removed.forEach(function (_a) {
        var size = _a.size;
        return _this.sizeMap.set(size, Math.max((_this.sizeMap.get(size) || 0) - 1, 0));
      });
    }
    var sorted = __spreadArray([], __read(this.sizeMap.entries()), false).sort(function (a, b) { return b[1] - a[1]; });
    var mostFrequentCount = sorted[0][1];
    var listEqual = sorted.filter(function (i) { return i[1] === mostFrequentCount; });
    if (listEqual.length > 1 && listEqual.find(function (i) { return i[0] === oldFrequentSizeCount; })) {
      // if there are more than 1 most frequent sizes, but the old one is present
      return;
    }
    this.frequentSize = sorted[0][0];
  };
  DefaultSize.prototype.recalculate = function (cacheSize) {
    if (this.sizeStrategy === SizeStrategy.Constant) {
      return false;
    }
    var _a = this.recalculation, oldItems = _a.oldItems, newItems = _a.newItems, removed = _a.removed;
    if (!oldItems.length && !newItems.length && !removed.length) {
      return false;
    }
    var oldValue = this.get();
    if (!cacheSize) {
      this.reset(true);
    }
    else {
      if (this.sizeStrategy === SizeStrategy.Average) {
        this.recalculateAverageSize(cacheSize);
      }
      else {
        this.recalculateFrequentSize();
      }
      this.recalculation.reset();
    }
    return this.get() !== oldValue;
  };
  DefaultSize.prototype.setExisted = function (oldSize, newSize) {
    if (this.sizeStrategy !== SizeStrategy.Constant) {
      this.recalculation.oldItems.push({
        size: oldSize,
        newSize: newSize
      });
    }
  };
  DefaultSize.prototype.setNew = function (size) {
    if (this.sizeStrategy !== SizeStrategy.Constant) {
      this.recalculation.newItems.push({ size: size });
    }
    else {
      if (!this.constantSize) {
        this.constantSize = size;
      }
    }
  };
  DefaultSize.prototype.setRemoved = function (size) {
    if (this.sizeStrategy !== SizeStrategy.Constant) {
      this.recalculation.removed.push({ size: size });
    }
  };
  return DefaultSize;
}());
export { DefaultSize };
//# sourceMappingURL=defaultSize.js.map