prepack/lib/partial-evaluators/IfStatement.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.default = function (ast, strictCode, env, realm) {
  let [exprValue, exprAst, exprIO] = env.partiallyEvaluateCompletionDeref(ast.test, strictCode);
  if (exprValue instanceof _completions.AbruptCompletion) return [exprValue, t.expressionStatement(exprAst), exprIO];
  let completion;
  if (exprValue instanceof _completions.PossiblyNormalCompletion) {
    completion = exprValue;
    exprValue = completion.value;
  }
  (0, _invariant2.default)(exprValue instanceof _index2.Value);

  if (!exprValue.mightNotBeTrue()) {
    // 3.a. Let stmtCompletion be the result of evaluating the first Statement
    let [stmtCompletion, stmtAst, stmtIO] = env.partiallyEvaluateCompletionDeref(ast.consequent, strictCode);

    // 5. Return Completion(UpdateEmpty(stmtCompletion, undefined)
    stmtCompletion = (0, _index.UpdateEmpty)(realm, stmtCompletion, realm.intrinsics.undefined);
    return [stmtCompletion, stmtAst, exprIO.concat(stmtIO)];
  } else if (!exprValue.mightNotBeFalse()) {
    let stmtCompletion, stmtAst, stmtIO;
    if (ast.alternate)
      // 4.a. Let stmtCompletion be the result of evaluating the second Statement
      [stmtCompletion, stmtAst, stmtIO] = env.partiallyEvaluateCompletionDeref(ast.alternate, strictCode);else {
      // 3 (of the if only statement). Return NormalCompletion(undefined)
      stmtCompletion = realm.intrinsics.undefined;
      stmtAst = t.emptyStatement();
      stmtIO = [];
    }
    // 5. Return Completion(UpdateEmpty(stmtCompletion, undefined)
    stmtCompletion = (0, _index.UpdateEmpty)(realm, stmtCompletion, realm.intrinsics.undefined);
    return [stmtCompletion, stmtAst, exprIO.concat(stmtIO)];
  }
  (0, _invariant2.default)(exprValue instanceof _index2.AbstractValue);

  // Evaluate consequent and alternate in sandboxes and get their effects.
  let [consequentEffects, conAst, conIO] = realm.partiallyEvaluateNodeForEffects(ast.consequent, strictCode, env);
  let [conCompl, gen1, bindings1, properties1, createdObj1] = consequentEffects;
  let consequentAst = conAst;
  if (conIO.length > 0) consequentAst = t.blockStatement(conIO.concat(consequentAst));

  let [alternateEffects, altAst, altIO] = ast.alternate ? realm.partiallyEvaluateNodeForEffects(ast.alternate, strictCode, env) : [(0, _realm.construct_empty_effects)(realm), undefined, []];
  let [altCompl, gen2, bindings2, properties2, createdObj2] = alternateEffects;
  let alternateAst = altAst;
  if (altIO.length > 0) alternateAst = t.blockStatement(altIO.concat(alternateAst));

  // Join the effects, creating an abstract view of what happened, regardless
  // of the actual value of exprValue.
  let joinedEffects = _singletons.Join.joinEffects(realm, exprValue, [conCompl, gen1, bindings1, properties1, createdObj1], [altCompl, gen2, bindings2, properties2, createdObj2]);
  completion = joinedEffects[0];
  if (completion instanceof _completions.PossiblyNormalCompletion) {
    // in this case one of the branches may complete abruptly, which means that
    // not all control flow branches join into one flow at this point.
    // Consequently we have to continue tracking changes until the point where
    // all the branches come together into one.
    realm.captureEffects(completion);
  }
  // Note that the effects of (non joining) abrupt branches are not included
  // in joinedEffects, but are tracked separately inside completion.
  realm.applyEffects(joinedEffects);

  let resultAst = t.ifStatement(exprAst, consequentAst, alternateAst);
  (0, _invariant2.default)(!(completion instanceof _environment.Reference));
  return [completion, resultAst, exprIO];
};

var _completions = require("../completions.js");

var _environment = require("../environment.js");

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

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

var _realm = require("../realm.js");

var _singletons = require("../singletons.js");

var _babelTypes = require("babel-types");

var t = _interopRequireWildcard(_babelTypes);

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

var _invariant2 = _interopRequireDefault(_invariant);

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

function _interopRequireWildcard(obj) { if (obj && obj.__esModule) { return obj; } else { var newObj = {}; if (obj != null) { for (var key in obj) { if (Object.prototype.hasOwnProperty.call(obj, key)) newObj[key] = obj[key]; } } newObj.default = obj; return newObj; } }
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