How to use esprima-fb - 10 common examples

var recast = require("recast");
var types = recast.types;
var through = require("through");
var esprima = require("esprima-fb");
var visitor = require("./visitor");

// Make sure that this esprima can parse async functions.
esprima.parse("async function test() {}");

function exports() {
  var data = [];
  return through(write, end);

  function write(buf) {
    data.push(buf);
  }

  function end() {
    this.queue(compile(data.join("")).code);
    this.queue(null);
  }
}

function compile(source, options) {

* 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.
 */
/*global exports:true*/

/**
 * Implements ES7 object spread property.
 * https://gist.github.com/sebmarkbage/aa849c7973cb4452c547
 *
 * { ...a, x: 1 }
 *
 * Object.assign({}, a, {x: 1 })
 *
 */

var Syntax = require('esprima-fb').Syntax;
var utils = require('../src/utils');

function visitObjectLiteralSpread(traverse, node, path, state) {
  utils.catchup(node.range[0], state);

  utils.append('Object.assign({', state);

  // Skip the original {
  utils.move(node.range[0] + 1, state);

  var lastWasSpread = renderSpreadProperties(
    traverse,
    node.properties,
    path,
    state,
    false // previousWasSpread

* you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*jslint node:true*/


var Syntax = require('esprima-fb').Syntax;
var utils = require('jstransform/src/utils');

function _nodeIsFunctionWithRestParam(node) {
  return (node.type === Syntax.FunctionDeclaration
          || node.type === Syntax.FunctionExpression
          || node.type === Syntax.ArrowFunctionExpression)
         && node.rest;
}

function visitFunctionParamsWithRestParam(traverse, node, path, state) {
  // Render params.
  if (node.params.length) {
    utils.catchup(node.params[node.params.length - 1].range[0], state);
    path.unshift(node);
    traverse(node.params[node.params.length - 1], path, state);
    path.shift();

function shouldAddDisplayName(object) {
  if (object &&
      object.type === Syntax.CallExpression &&
      object.callee.type === Syntax.MemberExpression &&
      object.callee.object.type === Syntax.Identifier &&
      object.callee.object.name === 'React' &&
      object.callee.property.type === Syntax.Identifier &&
      object.callee.property.name === 'createClass' &&
      object.arguments.length === 1 &&
      object.arguments[0].type === Syntax.ObjectExpression) {
    // Verify that the displayName property isn't already set
    var properties = object.arguments[0].properties;
    var safe = properties.every(function(property) {
      var value = property.key.type === Syntax.Identifier ?
        property.key.name :
        property.key.value;
      return value !== 'displayName';
    });
    return safe;
  }
  return false;

if (item.type === Syntax.SpreadProperty) {
      var restExpression = restPropertyHelpers.renderRestExpression(
        utils.getTempVar(tmpIndex),
        patternItems
      );
      components.push(item.argument.name + '=' + restExpression);
      continue;
    }

    // Depending on pattern type (Array or Object), we get
    // corresponding pattern item parts.
    var accessor = getPatternItemAccessor(node, item, tmpIndex, idx);
    var value = getPatternItemValue(node, item);

    // TODO(dmitrys): implement default values: {x, y=5}
    if (value.type === Syntax.Identifier) {
      // Simple pattern item.
      components.push(value.name + '=' + accessor);
    } else {
      // Complex sub-structure.
      components.push(
        utils.getTempVar(++state.localScope.tempVarIndex) + '=' + accessor +
        ',' + getDestructuredComponents(value, state)
      );
    }
  }

  return components.join(',');
}

function _getSuperClassInfo(node, state) {
  var ret = {
    name: null,
    expression: null
  };
  if (node.superClass) {
    if (node.superClass.type === Syntax.Identifier) {
      ret.name = node.superClass.name;
    } else {
      // Extension from an expression
      ret.name = _generateAnonymousClassName(state);
      ret.expression = state.g.source.substring(
        node.superClass.range[0],
        node.superClass.range[1]
      );
    }
  }
  return ret;
}

function reindentScript(script) {
    // We do another pass with Esprima in order to indent JS code correctly
    var outputAst = esprima.parse(script);
    return escodegen.generate(outputAst);
}

var transform = function(code, _context, options) {
    let ast = esprima.parse(code, { loc: true });
    let scopeManager = escope.analyze(ast);
    scopeManager.attach();

    scopeStack = new Stack();
    context = _context;
    contextName = "context" + Date.now();
    path = [];

    estraverse.replace(ast, {
        enter: (node, parent) => {
            if (node.__$escope$__) {
                let scope = {};
                let isRoot = scopeStack.size === 0;

                node.__$escope$__.variables.forEach(variable => {
                    // don't include variables from the context in the root scope

// Always munge identifiers that were declared within the method function
    // scope
    if (utils.identWithinLexicalScope(node.name, state, state.methodFuncNode)) {
      return true;
    }

    // Always munge private keys on object literals defined within a method's
    // scope.
    if (path[0].type === Syntax.Property
        && path[1].type === Syntax.ObjectExpression) {
      return true;
    }

    // Always munge function parameters
    if (path[0].type === Syntax.FunctionExpression
        || path[0].type === Syntax.FunctionDeclaration
        || path[0].type === Syntax.ArrowFunctionExpression) {
      for (var i = 0; i < path[0].params.length; i++) {
        if (path[0].params[i] === node) {
          return true;
        }
      }
    }
  }
  return false;
};

visitIdentifierUndefined.test = function(node, path, state) {
  if (
    node.type === Syntax.Identifier
      && node.name === 'undefined'
      && !utils.identWithinLexicalScope('undefined', state)
  ) {
    if (path[0]) {
      switch (path[0].type) {
        case Syntax.FunctionDeclaration:
        case Syntax.FunctionExpression:
        case Syntax.ArrowFunctionExpression:
          // skips: function params
          if (node !== path[0].body) {
            return false;
          }
          break;
        case Syntax.AssignmentExpression:
          // throws for: `undefined = foo` (where `undefined` is not declared)
          if (node === path[0].left) {
            throw new Error(
              'Illegal assignment to `undefined`. '
                + 'This breaks assumptions of the transform.'
            );
          }
          break;
        case Syntax.MemberExpression: