regenerator-transform/lib/visit.js

/**
 * Copyright (c) 2014-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

"use strict";

var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault");
var _assert = _interopRequireDefault(require("assert"));
var _hoist = require("./hoist");
var _emit = require("./emit");
var _replaceShorthandObjectMethod = _interopRequireDefault(require("./replaceShorthandObjectMethod"));
var util = _interopRequireWildcard(require("./util"));
function _getRequireWildcardCache(nodeInterop) { if (typeof WeakMap !== "function") return null; var cacheBabelInterop = new WeakMap(); var cacheNodeInterop = new WeakMap(); return (_getRequireWildcardCache = function _getRequireWildcardCache(nodeInterop) { return nodeInterop ? cacheNodeInterop : cacheBabelInterop; })(nodeInterop); }
function _interopRequireWildcard(obj, nodeInterop) { if (!nodeInterop && obj && obj.__esModule) { return obj; } if (obj === null || typeof obj !== "object" && typeof obj !== "function") { return { "default": obj }; } var cache = _getRequireWildcardCache(nodeInterop); if (cache && cache.has(obj)) { return cache.get(obj); } var newObj = {}; var hasPropertyDescriptor = Object.defineProperty && Object.getOwnPropertyDescriptor; for (var key in obj) { if (key !== "default" && 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; }
exports.getVisitor = function (_ref) {
  var t = _ref.types;
  return {
    Method: function Method(path, state) {
      var node = path.node;
      if (!shouldRegenerate(node, state)) return;
      var container = t.functionExpression(null, [], t.cloneNode(node.body, false), node.generator, node.async);
      path.get("body").set("body", [t.returnStatement(t.callExpression(container, []))]);

      // Regardless of whether or not the wrapped function is a an async method
      // or generator the outer function should not be
      node.async = false;
      node.generator = false;

      // Unwrap the wrapper IIFE's environment so super and this and such still work.
      path.get("body.body.0.argument.callee").unwrapFunctionEnvironment();
    },
    Function: {
      exit: util.wrapWithTypes(t, function (path, state) {
        var node = path.node;
        if (!shouldRegenerate(node, state)) return;

        // if this is an ObjectMethod, we need to convert it to an ObjectProperty
        path = (0, _replaceShorthandObjectMethod["default"])(path);
        node = path.node;
        var contextId = path.scope.generateUidIdentifier("context");
        var argsId = path.scope.generateUidIdentifier("args");
        path.ensureBlock();
        var bodyBlockPath = path.get("body");
        if (node.async) {
          bodyBlockPath.traverse(awaitVisitor);
        }
        bodyBlockPath.traverse(functionSentVisitor, {
          context: contextId
        });
        var outerBody = [];
        var innerBody = [];
        bodyBlockPath.get("body").forEach(function (childPath) {
          var node = childPath.node;
          if (t.isExpressionStatement(node) && t.isStringLiteral(node.expression)) {
            // Babylon represents directives like "use strict" as elements
            // of a bodyBlockPath.node.directives array, but they could just
            // as easily be represented (by other parsers) as traditional
            // string-literal-valued expression statements, so we need to
            // handle that here. (#248)
            outerBody.push(node);
          } else if (node && node._blockHoist != null) {
            outerBody.push(node);
          } else {
            innerBody.push(node);
          }
        });
        if (outerBody.length > 0) {
          // Only replace the inner body if we actually hoisted any statements
          // to the outer body.
          bodyBlockPath.node.body = innerBody;
        }
        var outerFnExpr = getOuterFnExpr(path);
        // Note that getOuterFnExpr has the side-effect of ensuring that the
        // function has a name (so node.id will always be an Identifier), even
        // if a temporary name has to be synthesized.
        t.assertIdentifier(node.id);
        var innerFnId = t.identifier(node.id.name + "$");

        // Turn all declarations into vars, and replace the original
        // declarations with equivalent assignment expressions.
        var vars = (0, _hoist.hoist)(path);
        var context = {
          usesThis: false,
          usesArguments: false,
          getArgsId: function getArgsId() {
            return t.clone(argsId);
          }
        };
        path.traverse(argumentsThisVisitor, context);
        if (context.usesArguments) {
          vars = vars || t.variableDeclaration("var", []);
          vars.declarations.push(t.variableDeclarator(t.clone(argsId), t.identifier("arguments")));
        }
        var emitter = new _emit.Emitter(contextId);
        emitter.explode(path.get("body"));
        if (vars && vars.declarations.length > 0) {
          outerBody.push(vars);
        }
        var wrapArgs = [emitter.getContextFunction(innerFnId)];
        var tryLocsList = emitter.getTryLocsList();
        if (node.generator) {
          wrapArgs.push(outerFnExpr);
        } else if (context.usesThis || tryLocsList || node.async) {
          // Async functions that are not generators don't care about the
          // outer function because they don't need it to be marked and don't
          // inherit from its .prototype.
          wrapArgs.push(t.nullLiteral());
        }
        if (context.usesThis) {
          wrapArgs.push(t.thisExpression());
        } else if (tryLocsList || node.async) {
          wrapArgs.push(t.nullLiteral());
        }
        if (tryLocsList) {
          wrapArgs.push(tryLocsList);
        } else if (node.async) {
          wrapArgs.push(t.nullLiteral());
        }
        if (node.async) {
          // Rename any locally declared "Promise" variable,
          // to use the global one.
          var currentScope = path.scope;
          do {
            if (currentScope.hasOwnBinding("Promise")) currentScope.rename("Promise");
          } while (currentScope = currentScope.parent);
          wrapArgs.push(t.identifier("Promise"));
        }
        var wrapCall = t.callExpression(util.runtimeProperty(node.async ? "async" : "wrap"), wrapArgs);
        outerBody.push(t.returnStatement(wrapCall));
        node.body = t.blockStatement(outerBody);
        // We injected a few new variable declarations (for every hoisted var),
        // so we need to add them to the scope.
        path.get("body.body").forEach(function (p) {
          return p.scope.registerDeclaration(p);
        });
        var oldDirectives = bodyBlockPath.node.directives;
        if (oldDirectives) {
          // Babylon represents directives like "use strict" as elements of
          // a bodyBlockPath.node.directives array. (#248)
          node.body.directives = oldDirectives;
        }
        var wasGeneratorFunction = node.generator;
        if (wasGeneratorFunction) {
          node.generator = false;
        }
        if (node.async) {
          node.async = false;
        }
        if (wasGeneratorFunction && t.isExpression(node)) {
          util.replaceWithOrRemove(path, t.callExpression(util.runtimeProperty("mark"), [node]));
          path.addComment("leading", "#__PURE__");
        }
        var insertedLocs = emitter.getInsertedLocs();
        path.traverse({
          NumericLiteral: function NumericLiteral(path) {
            if (!insertedLocs.has(path.node)) {
              return;
            }
            path.replaceWith(t.numericLiteral(path.node.value));
          }
        });

        // Generators are processed in 'exit' handlers so that regenerator only has to run on
        // an ES5 AST, but that means traversal will not pick up newly inserted references
        // to things like 'regeneratorRuntime'. To avoid this, we explicitly requeue.
        path.requeue();
      })
    }
  };
};

// Check if a node should be transformed by regenerator
function shouldRegenerate(node, state) {
  if (node.generator) {
    if (node.async) {
      // Async generator
      return state.opts.asyncGenerators !== false;
    } else {
      // Plain generator
      return state.opts.generators !== false;
    }
  } else if (node.async) {
    // Async function
    return state.opts.async !== false;
  } else {
    // Not a generator or async function.
    return false;
  }
}

// Given a NodePath for a Function, return an Expression node that can be
// used to refer reliably to the function object from inside the function.
// This expression is essentially a replacement for arguments.callee, with
// the key advantage that it works in strict mode.
function getOuterFnExpr(funPath) {
  var t = util.getTypes();
  var node = funPath.node;
  t.assertFunction(node);
  if (!node.id) {
    // Default-exported function declarations, and function expressions may not
    // have a name to reference, so we explicitly add one.
    node.id = funPath.scope.parent.generateUidIdentifier("callee");
  }
  if (node.generator &&
  // Non-generator functions don't need to be marked.
  t.isFunctionDeclaration(node)) {
    // Return the identifier returned by runtime.mark(<node.id>).
    return getMarkedFunctionId(funPath);
  }
  return t.clone(node.id);
}
var markInfo = new WeakMap();
function getMarkInfo(node) {
  if (!markInfo.has(node)) {
    markInfo.set(node, {});
  }
  return markInfo.get(node);
}
function getMarkedFunctionId(funPath) {
  var t = util.getTypes();
  var node = funPath.node;
  t.assertIdentifier(node.id);
  var blockPath = funPath.findParent(function (path) {
    return path.isProgram() || path.isBlockStatement();
  });
  if (!blockPath) {
    return node.id;
  }
  var block = blockPath.node;
  _assert["default"].ok(Array.isArray(block.body));
  var info = getMarkInfo(block);
  if (!info.decl) {
    info.decl = t.variableDeclaration("var", []);
    blockPath.unshiftContainer("body", info.decl);
    info.declPath = blockPath.get("body.0");
  }
  _assert["default"].strictEqual(info.declPath.node, info.decl);

  // Get a new unique identifier for our marked variable.
  var markedId = blockPath.scope.generateUidIdentifier("marked");
  var markCallExp = t.callExpression(util.runtimeProperty("mark"), [t.clone(node.id)]);
  var index = info.decl.declarations.push(t.variableDeclarator(markedId, markCallExp)) - 1;
  var markCallExpPath = info.declPath.get("declarations." + index + ".init");
  _assert["default"].strictEqual(markCallExpPath.node, markCallExp);
  markCallExpPath.addComment("leading", "#__PURE__");
  return t.clone(markedId);
}
var argumentsThisVisitor = {
  "FunctionExpression|FunctionDeclaration|Method": function FunctionExpressionFunctionDeclarationMethod(path) {
    path.skip();
  },
  Identifier: function Identifier(path, state) {
    if (path.node.name === "arguments" && util.isReference(path)) {
      util.replaceWithOrRemove(path, state.getArgsId());
      state.usesArguments = true;
    }
  },
  ThisExpression: function ThisExpression(path, state) {
    state.usesThis = true;
  }
};
var functionSentVisitor = {
  MetaProperty: function MetaProperty(path) {
    var node = path.node;
    if (node.meta.name === "function" && node.property.name === "sent") {
      var t = util.getTypes();
      util.replaceWithOrRemove(path, t.memberExpression(t.clone(this.context), t.identifier("_sent")));
    }
  }
};
var awaitVisitor = {
  Function: function Function(path) {
    path.skip(); // Don't descend into nested function scopes.
  },

  AwaitExpression: function AwaitExpression(path) {
    var t = util.getTypes();

    // Convert await expressions to yield expressions.
    var argument = path.node.argument;

    // Transforming `await x` to `yield regeneratorRuntime.awrap(x)`
    // causes the argument to be wrapped in such a way that the runtime
    // can distinguish between awaited and merely yielded values.
    util.replaceWithOrRemove(path, t.yieldExpression(t.callExpression(util.runtimeProperty("awrap"), [argument]), false));
  }
};