prepack/lib/serializer/utils.js

Execute a JS bundle, serialize global state and side effects to a snapshot that can be quickly restored.

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.getSuggestedArrayLiteralLength = getSuggestedArrayLiteralLength;
exports.commonAncestorOf = commonAncestorOf;
exports.getOrDefault = getOrDefault;
exports.withDescriptorValue = withDescriptorValue;
exports.canIgnoreClassLengthProperty = canIgnoreClassLengthProperty;
exports.getObjectPrototypeMetadata = getObjectPrototypeMetadata;
exports.createAdditionalEffects = createAdditionalEffects;
exports.handleReportedSideEffect = handleReportedSideEffect;
exports.ClassPropertiesToIgnore = void 0;

var _index = require("../values/index.js");

var _errors = require("../errors.js");

var _invariant = _interopRequireDefault(require("../invariant.js"));

var _index2 = require("../methods/index.js");

var _logger = require("../utils/logger.js");

var _generator = require("../utils/generator.js");

var _babelhelpers = require("../utils/babelhelpers.js");

var _descriptors = require("../descriptors.js");

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

/**
 * Copyright (c) 2017-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 */

/**
 * Get index property list length by searching array properties list for the max index key value plus 1.
 * If tail elements are conditional, return the minimum length if an assignment to the length property
 * can be avoided because of that. The boolean part of the result is a flag that indicates if the latter is true.
 */
function getSuggestedArrayLiteralLength(realm, val) {
  (0, _invariant.default)((0, _index2.IsArray)(realm, val));
  let instantRenderMode = realm.instantRender.enabled;
  let minLength = 0,
      maxLength = 0;
  let actualLength;

  for (const key of val.properties.keys()) {
    if ((0, _index2.IsArrayIndex)(realm, key) && Number(key) >= maxLength) {
      let prevMax = maxLength;
      maxLength = Number(key) + 1;

      let elem = val._SafeGetDataPropertyValue(key);

      if (instantRenderMode || !elem.mightHaveBeenDeleted()) minLength = maxLength;else if (elem instanceof _index.AbstractValue && elem.kind === "conditional") {
        let maxLengthVal = new _index.IntegralValue(realm, maxLength);
        let [c, x, y] = elem.args;

        if (x instanceof _index.EmptyValue && !y.mightHaveBeenDeleted()) {
          let prevActual = actualLength === undefined ? new _index.IntegralValue(realm, prevMax) : actualLength;
          actualLength = _index.AbstractValue.createFromConditionalOp(realm, c, prevActual, maxLengthVal);
        } else if (y instanceof _index.EmptyValue && !x.mightHaveBeenDeleted()) {
          let prevActual = actualLength === undefined ? new _index.IntegralValue(realm, prevMax) : actualLength;
          actualLength = _index.AbstractValue.createFromConditionalOp(realm, c, maxLengthVal, prevActual);
        } else {
          actualLength = undefined;
        }
      }
    }
  }

  if (maxLength > minLength && actualLength instanceof _index.AbstractValue) {
    let lengthVal = val._SafeGetDataPropertyValue("length");

    if (lengthVal.equals(actualLength)) return [minLength, true];
  }

  return [maxLength, false];
}

function commonAncestorOf(node1, node2, getParent) {
  if (node1 === node2) return node1; // First get the path length to the root node for both nodes while also checking if
  // either node is the parent of the other.

  let n1 = node1,
      n2 = node2,
      count1 = 0,
      count2 = 0;

  while (true) {
    let p1 = n1 && getParent(n1);
    let p2 = n2 && getParent(n2);
    if (p1 === node2) return node2;
    if (p2 === node1) return node1;
    if (p1 !== undefined) count1++;
    if (p2 !== undefined) count2++;
    if (p1 === undefined && p2 === undefined) break;
    n1 = p1;
    n2 = p2;
  } // Now shorten the longest path to the same length as the shorter path


  n1 = node1;

  while (count1 > count2) {
    (0, _invariant.default)(n1 !== undefined);
    n1 = getParent(n1);
    count1--;
  }

  n2 = node2;

  while (count1 < count2) {
    (0, _invariant.default)(n2 !== undefined);
    n2 = getParent(n2);
    count2--;
  } // Now run up both paths in tandem, stopping at the first common entry


  while (n1 !== n2) {
    (0, _invariant.default)(n1 !== undefined);
    n1 = getParent(n1);
    (0, _invariant.default)(n2 !== undefined);
    n2 = getParent(n2);
  }

  return n1;
} // Gets map[key] with default value provided by defaultFn


function getOrDefault(map, key, defaultFn) {
  let value = map.get(key);
  if (value === undefined) map.set(key, value = defaultFn());
  (0, _invariant.default)(value !== undefined);
  return value;
}

function withDescriptorValue(propertyNameOrSymbol, descriptor, func) {
  if (descriptor !== undefined) {
    (0, _invariant.default)(descriptor instanceof _descriptors.PropertyDescriptor); // TODO: Handle joined descriptors.

    if (descriptor.value !== undefined) {
      func(propertyNameOrSymbol, descriptor.value, "value");
    } else {
      if (descriptor.get !== undefined) {
        func(propertyNameOrSymbol, descriptor.get, "get");
      }

      if (descriptor.set !== undefined) {
        func(propertyNameOrSymbol, descriptor.set, "set");
      }
    }
  }
}

const ClassPropertiesToIgnore = new Set(["arguments", "name", "caller"]);
exports.ClassPropertiesToIgnore = ClassPropertiesToIgnore;

function canIgnoreClassLengthProperty(val, desc, logger) {
  if (desc) {
    if (desc instanceof _descriptors.PropertyDescriptor) {
      if (desc.value === undefined) {
        logger.logError(val, "Functions with length accessor properties are not supported in residual heap.");
      }
    } else {
      logger.logError(val, "Functions with length properties with different attributes are not supported in residual heap.");
    }
  }

  return true;
}

function getObjectPrototypeMetadata(realm, obj) {
  let proto = obj.$Prototype;
  let skipPrototype = false;
  let constructor;

  if (obj.$IsClassPrototype) {
    skipPrototype = true;
  }

  if (proto && proto.$IsClassPrototype) {
    (0, _invariant.default)(proto instanceof _index.ObjectValue); // we now need to check if the prototpe has a constructor

    let _constructor = proto.properties.get("constructor");

    if (_constructor !== undefined) {
      // if the contructor has been deleted then we have no way
      // to serialize the original class AST as it won't have been
      // evluated and thus visited
      if (_constructor.descriptor === undefined) {
        throw new _errors.FatalError("TODO #1024: implement object prototype serialization with deleted constructor");
      }

      if (!(_constructor.descriptor instanceof _descriptors.PropertyDescriptor)) {
        throw new _errors.FatalError("TODO #1024: implement object prototype serialization with multiple constructor attributes");
      }

      let classFunc = _constructor.descriptor.value;

      if (classFunc instanceof _index.ECMAScriptSourceFunctionValue) {
        constructor = classFunc;
        skipPrototype = true;
      }
    }
  }

  return {
    skipPrototype,
    constructor
  };
}

function createAdditionalEffects(realm, effects, fatalOnAbrupt, name, additionalFunctionEffects, preEvaluationComponentToWriteEffectFunction, optimizedFunction, parentOptimizedFunction, transforms = []) {
  let generator = _generator.Generator.fromEffects(effects, realm, name, additionalFunctionEffects, preEvaluationComponentToWriteEffectFunction, optimizedFunction);

  let retValue = {
    parentAdditionalFunction: parentOptimizedFunction || undefined,
    effects,
    transforms,
    generator,
    additionalRoots: new Set()
  };
  return retValue;
}

function handleReportedSideEffect(exceptionHandler, sideEffectType, binding, expressionLocation) {
  // This causes an infinite recursion because creating a callstack causes internal-only side effects
  if (binding && binding.object && binding.object.intrinsicName === "__checkedBindings") return;
  let location = (0, _babelhelpers.optionalStringOfLocation)(expressionLocation);

  if (sideEffectType === "MODIFIED_BINDING") {
    let name = binding ? `"${binding.name}"` : "unknown";
    exceptionHandler(`side-effects from mutating the binding ${name}${location}`, expressionLocation);
  } else if (sideEffectType === "MODIFIED_PROPERTY" || sideEffectType === "MODIFIED_GLOBAL") {
    let name = "";
    let pb = binding;
    let key = pb.key;

    if (typeof key === "string") {
      name = `"${key}"`;
    }

    if (sideEffectType === "MODIFIED_PROPERTY") {
      if (!_index.ObjectValue.refuseSerializationOnPropertyBinding(pb)) exceptionHandler(`side-effects from mutating a property ${name}${location}`, expressionLocation);
    } else {
      exceptionHandler(`side-effects from mutating the global object property ${name}${location}`, expressionLocation);
    }
  } else if (sideEffectType === "EXCEPTION_THROWN") {
    exceptionHandler(`side-effects from throwing exception${location}`, expressionLocation);
  }
}
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