index.js

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = memberExpressionToFunctions;

var t = _interopRequireWildcard(require("@babel/types"));

function _getRequireWildcardCache() { if (typeof WeakMap !== "function") return null; var cache = new WeakMap(); _getRequireWildcardCache = function () { return cache; }; return cache; }

function _interopRequireWildcard(obj) { if (obj && obj.__esModule) { return obj; } var cache = _getRequireWildcardCache(); if (cache && cache.has(obj)) { return cache.get(obj); } var newObj = {}; if (obj != null) { var hasPropertyDescriptor = Object.defineProperty && Object.getOwnPropertyDescriptor; for (var key in obj) { if (Object.prototype.hasOwnProperty.call(obj, key)) { var desc = hasPropertyDescriptor ? Object.getOwnPropertyDescriptor(obj, key) : null; if (desc && (desc.get || desc.set)) { Object.defineProperty(newObj, key, desc); } else { newObj[key] = obj[key]; } } } } newObj.default = obj; if (cache) { cache.set(obj, newObj); } return newObj; }

class AssignmentMemoiser {
  constructor() {
    this._map = new WeakMap();
  }

  has(key) {
    return this._map.has(key);
  }

  get(key) {
    if (!this.has(key)) return;

    const record = this._map.get(key);

    const {
      value
    } = record;
    record.count--;

    if (record.count === 0) {
      return t.assignmentExpression("=", value, key);
    }

    return value;
  }

  set(key, value, count) {
    return this._map.set(key, {
      count,
      value
    });
  }

}

const handle = {
  memoise() {},

  handle(member) {
    const {
      node,
      parent,
      parentPath
    } = member;

    if (parentPath.isUpdateExpression({
      argument: node
    })) {
      const {
        operator,
        prefix
      } = parent;
      this.memoise(member, 2);
      const value = t.binaryExpression(operator[0], t.unaryExpression("+", this.get(member)), t.numericLiteral(1));

      if (prefix) {
        parentPath.replaceWith(this.set(member, value));
      } else {
        const {
          scope
        } = member;
        const ref = scope.generateUidIdentifierBasedOnNode(node);
        scope.push({
          id: ref
        });
        value.left = t.assignmentExpression("=", t.cloneNode(ref), value.left);
        parentPath.replaceWith(t.sequenceExpression([this.set(member, value), t.cloneNode(ref)]));
      }

      return;
    }

    if (parentPath.isAssignmentExpression({
      left: node
    })) {
      const {
        operator,
        right
      } = parent;
      let value = right;

      if (operator !== "=") {
        this.memoise(member, 2);
        value = t.binaryExpression(operator.slice(0, -1), this.get(member), value);
      }

      parentPath.replaceWith(this.set(member, value));
      return;
    }

    if (parentPath.isCallExpression({
      callee: node
    })) {
      const {
        arguments: args
      } = parent;
      parentPath.replaceWith(this.call(member, args));
      return;
    }

    if (parentPath.isObjectProperty({
      value: node
    }) && parentPath.parentPath.isObjectPattern() || parentPath.isAssignmentPattern({
      left: node
    }) && parentPath.parentPath.isObjectProperty({
      value: parent
    }) && parentPath.parentPath.parentPath.isObjectPattern() || parentPath.isArrayPattern() || parentPath.isAssignmentPattern({
      left: node
    }) && parentPath.parentPath.isArrayPattern() || parentPath.isRestElement()) {
      member.replaceWith(this.destructureSet(member));
      return;
    }

    member.replaceWith(this.get(member));
  }

};

function memberExpressionToFunctions(path, visitor, state) {
  path.traverse(visitor, Object.assign({}, handle, {}, state, {
    memoiser: new AssignmentMemoiser()
  }));
}