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authorruki <waruqi@gmail.com>2018-11-08 00:38:48 +0800
committerruki <waruqi@gmail.com>2018-11-07 21:53:09 +0800
commit26105034da4fcce7ac883c899d781f016559310d (patch)
treec459a5dc4e3aa0972d9919033ece511ce76dd129 /node_modules/regenerator-transform/lib/meta.js
parent2c77f00f1a7ecb6c8192f9c16d3b2001b254a107 (diff)
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+"use strict";
+
+var _assert = require("assert");
+
+var _assert2 = _interopRequireDefault(_assert);
+
+var _util = require("./util.js");
+
+function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
+
+/**
+ * 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.
+ */
+
+var m = require("private").makeAccessor();
+var hasOwn = Object.prototype.hasOwnProperty;
+
+function makePredicate(propertyName, knownTypes) {
+ function onlyChildren(node) {
+ var t = (0, _util.getTypes)();
+ t.assertNode(node);
+
+ // Assume no side effects until we find out otherwise.
+ var result = false;
+
+ function check(child) {
+ if (result) {
+ // Do nothing.
+ } else if (Array.isArray(child)) {
+ child.some(check);
+ } else if (t.isNode(child)) {
+ _assert2.default.strictEqual(result, false);
+ result = predicate(child);
+ }
+ return result;
+ }
+
+ var keys = t.VISITOR_KEYS[node.type];
+ if (keys) {
+ for (var i = 0; i < keys.length; i++) {
+ var key = keys[i];
+ var child = node[key];
+ check(child);
+ }
+ }
+
+ return result;
+ }
+
+ function predicate(node) {
+ (0, _util.getTypes)().assertNode(node);
+
+ var meta = m(node);
+ if (hasOwn.call(meta, propertyName)) return meta[propertyName];
+
+ // Certain types are "opaque," which means they have no side
+ // effects or leaps and we don't care about their subexpressions.
+ if (hasOwn.call(opaqueTypes, node.type)) return meta[propertyName] = false;
+
+ if (hasOwn.call(knownTypes, node.type)) return meta[propertyName] = true;
+
+ return meta[propertyName] = onlyChildren(node);
+ }
+
+ predicate.onlyChildren = onlyChildren;
+
+ return predicate;
+}
+
+var opaqueTypes = {
+ FunctionExpression: true,
+ ArrowFunctionExpression: true
+};
+
+// These types potentially have side effects regardless of what side
+// effects their subexpressions have.
+var sideEffectTypes = {
+ CallExpression: true, // Anything could happen!
+ ForInStatement: true, // Modifies the key variable.
+ UnaryExpression: true, // Think delete.
+ BinaryExpression: true, // Might invoke .toString() or .valueOf().
+ AssignmentExpression: true, // Side-effecting by definition.
+ UpdateExpression: true, // Updates are essentially assignments.
+ NewExpression: true // Similar to CallExpression.
+};
+
+// These types are the direct cause of all leaps in control flow.
+var leapTypes = {
+ YieldExpression: true,
+ BreakStatement: true,
+ ContinueStatement: true,
+ ReturnStatement: true,
+ ThrowStatement: true
+};
+
+// All leap types are also side effect types.
+for (var type in leapTypes) {
+ if (hasOwn.call(leapTypes, type)) {
+ sideEffectTypes[type] = leapTypes[type];
+ }
+}
+
+exports.hasSideEffects = makePredicate("hasSideEffects", sideEffectTypes);
+exports.containsLeap = makePredicate("containsLeap", leapTypes); \ No newline at end of file