WIP - add extractor, generate snippet_data

node_modules/babel-plugin-minify-mangle-names/lib/index.js

@@ -0,0 +1,618 @@
+"use strict";
+
+var _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();
+
+function _toConsumableArray(arr) { if (Array.isArray(arr)) { for (var i = 0, arr2 = Array(arr.length); i < arr.length; i++) { arr2[i] = arr[i]; } return arr2; } else { return Array.from(arr); } }
+
+function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
+
+var Charset = require("./charset");
+var ScopeTracker = require("./scope-tracker");
+var isLabelIdentifier = require("./is-label-identifier");
+var bfsTraverseCreator = require("./bfs-traverse");
+var fixupVarScoping = require("./fixup-var-scoping");
+
+var _require = require("babel-helper-mark-eval-scopes"),
+    markEvalScopes = _require.markEvalScopes,
+    isEvalScopesMarked = _require.isMarked,
+    hasEval = _require.hasEval;
+
+var newIssueUrl = "https://github.com/babel/minify/issues/new";
+
+module.exports = function (babel) {
+  var t = babel.types,
+      traverse = babel.traverse;
+
+  var bfsTraverse = bfsTraverseCreator(babel);
+  var hop = Object.prototype.hasOwnProperty;
+
+  var Mangler = function () {
+    function Mangler(charset, program) {
+      var _ref = arguments.length > 2 && arguments[2] !== undefined ? arguments[2] : {},
+          _ref$exclude = _ref.exclude,
+          exclude = _ref$exclude === undefined ? {} : _ref$exclude,
+          _ref$keepFnName = _ref.keepFnName,
+          keepFnName = _ref$keepFnName === undefined ? false : _ref$keepFnName,
+          _ref$keepClassName = _ref.keepClassName,
+          keepClassName = _ref$keepClassName === undefined ? false : _ref$keepClassName,
+          _ref$eval = _ref.eval,
+          _eval = _ref$eval === undefined ? false : _ref$eval,
+          _ref$topLevel = _ref.topLevel,
+          topLevel = _ref$topLevel === undefined ? false : _ref$topLevel;
+
+      _classCallCheck(this, Mangler);
+
+      this.charset = charset;
+      this.program = program;
+
+      // user passed options
+      this.exclude = toObject(exclude);
+      this.keepFnName = keepFnName;
+      this.keepClassName = keepClassName;
+      this.topLevel = topLevel;
+      this.eval = _eval;
+
+      // tracking
+      this.visitedScopes = new Set();
+      this.scopeTracker = new ScopeTracker();
+      this.renamedNodes = new Set();
+    }
+
+    /**
+     * Run the mangler
+     */
+
+
+    _createClass(Mangler, [{
+      key: "run",
+      value: function run() {
+        this.crawlScope();
+        this.collect();
+        this.fixup();
+        this.charset.sort();
+        this.mangle();
+      }
+
+      /**
+       * Tells if a variable name is excluded
+       * @param {String} name
+       */
+
+    }, {
+      key: "isExcluded",
+      value: function isExcluded(name) {
+        return hop.call(this.exclude, name) && this.exclude[name];
+      }
+
+      /**
+       * Clears traverse cache and recrawls the AST
+       *
+       * to recompute the bindings, references, other scope information
+       * and paths because the other transformations in the same pipeline
+       * (other plugins and presets) changes the AST and does NOT update
+       * the scope objects
+       */
+
+    }, {
+      key: "crawlScope",
+      value: function crawlScope() {
+        (traverse.clearCache || traverse.cache.clear)();
+        this.program.scope.crawl();
+      }
+
+      /**
+       * Re-crawling comes with a side-effect that let->var conversion
+       * reverts the update of the binding information (block to fn scope).
+       * This function takes care of it by updating it again.
+       *
+       * TODO: This is unnecessary work and needs to be fixed in babel.
+       * https://github.com/babel/babel/issues/4818
+       *
+       * When this is removed, remember to remove fixup's dependency in
+       * ScopeTracker
+       */
+
+    }, {
+      key: "fixup",
+      value: function fixup() {
+        fixupVarScoping(this);
+      }
+
+      /**
+       * A single pass through the AST to collect info for
+       *
+       * 1. Scope Tracker
+       * 2. Unsafe Scopes (direct eval scopes)
+       * 3. Charset considerations for better gzip compression
+       *
+       * Traversed in the same fashion(BFS) the mangling is done
+       */
+
+    }, {
+      key: "collect",
+      value: function collect() {
+        var mangler = this;
+        var scopeTracker = mangler.scopeTracker;
+
+
+        scopeTracker.addScope(this.program.scope);
+
+        /**
+         * Same usage as in DCE, whichever runs first
+         */
+
+        if (!isEvalScopesMarked(mangler.program)) {
+          markEvalScopes(mangler.program);
+        }
+
+        /**
+         * The visitors to be used in traversal.
+         *
+         * Note: BFS traversal supports only the `enter` handlers, `exit`
+         * handlers are simply dropped without Errors
+         *
+         * Collects items defined in the ScopeTracker
+         */
+        var collectVisitor = {
+          Scopable(_ref2) {
+            var scope = _ref2.scope;
+
+            scopeTracker.addScope(scope);
+
+            // Collect bindings defined in the scope
+            Object.keys(scope.bindings).forEach(function (name) {
+              scopeTracker.addBinding(scope.bindings[name]);
+            });
+          },
+          /**
+           * This is necessary because, in Babel, the scope.references
+           * does NOT contain the references in that scope. Only the program
+           * scope (top most level) contains all the references.
+           *
+           * We collect the references in a fashion where all the scopes between
+           * and including the referenced scope and scope where it is declared
+           * is considered as scope referencing that identifier
+           */
+          ReferencedIdentifier(path) {
+            if (isLabelIdentifier(path)) return;
+            var scope = path.scope,
+                name = path.node.name;
+
+            var binding = scope.getBinding(name);
+            if (!binding) {
+              // Do not collect globals as they are already available via
+              // babel's API
+              if (scope.hasGlobal(name)) return;
+              // This should NOT happen ultimately. Panic if this code block is
+              // reached
+              throw new Error(`Binding not found for ReferencedIdentifier "${name}" ` + `present in "${path.parentPath.type}". ` + `Please report this at ${newIssueUrl}`);
+            } else {
+              // Add it to our scope tracker if everything is fine
+              scopeTracker.addReference(scope, binding, name);
+            }
+          },
+
+          /**
+           * This is useful to detect binding ids and add them to the
+           * scopeTracker's bindings
+           *
+           * TODO:
+           *
+           * This visitor is probably unnecessary. It was added to capture the
+           * bindings that was not present in scope.bindings. But, now, it looks
+           * like the unit and smoke tests pass without this.
+           */
+          BindingIdentifier(path) {
+            if (isLabelIdentifier(path)) return;
+
+            var scope = path.scope,
+                name = path.node.name;
+
+            var binding = scope.getBinding(name);
+
+            /**
+             * We have already captured the bindings when traversing through
+             * Scopables, if a binding identifier doesn't have a binding, it
+             * probably means that another transformation created a new binding,
+             * refer https://github.com/babel/minify/issues/549 for example -
+             * binding created by plugin transform-es2015-function-name
+             *
+             * So we just don't care about bindings that do not exist
+             *
+             * TODO:
+             *
+             * this deopts in DCE as this name can be removed for this particular
+             * case (es2015-function-name)
+             */
+            if (!binding) return;
+
+            /**
+             * Detect constant violations
+             *
+             * If it's a constant violation, then add the Identifier Path as
+             * a Reference instead of Binding - This is because the ScopeTracker
+             * tracks these Re-declaration and mutation of variables as References
+             * as it is simple to rename them
+             */
+            if (binding.identifier === path.node) {
+              scopeTracker.addBinding(binding);
+            } else {
+              // constant violation
+              scopeTracker.addReference(scope, binding, name);
+            }
+          }
+        };
+
+        /**
+         * These visitors are for collecting the Characters used in the program
+         * to measure the frequency and generate variable names for mangling so
+         * as to improve the gzip compression - as gzip likes repetition
+         */
+        if (this.charset.shouldConsider) {
+          collectVisitor.Identifier = function Identifer(path) {
+            var node = path.node;
+
+            // We don't mangle properties, so we collect them as they contribute
+            // to the frequency of characters
+
+            if (path.parentPath.isMemberExpression({ property: node }) || path.parentPath.isObjectProperty({ key: node })) {
+              mangler.charset.consider(node.name);
+            }
+          };
+          collectVisitor.Literal = function Literal(_ref3) {
+            var node = _ref3.node;
+
+            mangler.charset.consider(String(node.value));
+          };
+        }
+
+        // Traverse the AST
+        bfsTraverse(mangler.program, collectVisitor);
+      }
+
+      /**
+       * Tells if a binding is exported as a NamedExport - so as to NOT mangle
+       *
+       * Babel treats NamedExports as a binding referenced by this NamedExport decl
+       * @param {Binding} binding
+       */
+
+    }, {
+      key: "isExportedWithName",
+      value: function isExportedWithName(binding) {
+        // short circuit
+        if (!this.topLevel) {
+          return false;
+        }
+
+        var refs = binding.referencePaths;
+
+        var _iteratorNormalCompletion = true;
+        var _didIteratorError = false;
+        var _iteratorError = undefined;
+
+        try {
+          for (var _iterator = refs[Symbol.iterator](), _step; !(_iteratorNormalCompletion = (_step = _iterator.next()).done); _iteratorNormalCompletion = true) {
+            var ref = _step.value;
+
+            if (ref.isExportNamedDeclaration()) {
+              return true;
+            }
+          }
+
+          // default
+        } catch (err) {
+          _didIteratorError = true;
+          _iteratorError = err;
+        } finally {
+          try {
+            if (!_iteratorNormalCompletion && _iterator.return) {
+              _iterator.return();
+            }
+          } finally {
+            if (_didIteratorError) {
+              throw _iteratorError;
+            }
+          }
+        }
+
+        return false;
+      }
+
+      /**
+       * Mangle the scope
+       * @param {Scope} scope
+       */
+
+    }, {
+      key: "mangleScope",
+      value: function mangleScope(scope) {
+        var mangler = this;
+        var scopeTracker = mangler.scopeTracker;
+
+        // Unsafe Scope
+
+        if (!mangler.eval && hasEval(scope)) return;
+
+        // Already visited
+        // This is because for a function, in Babel, the function and
+        // the function body's BlockStatement has the same scope, and will
+        // be visited twice by the Scopable handler, and we want to mangle
+        // it only once
+        if (mangler.visitedScopes.has(scope)) return;
+        mangler.visitedScopes.add(scope);
+
+        // Helpers to generate names
+        var i = 0;
+        function getNext() {
+          return mangler.charset.getIdentifier(i++);
+        }
+        function resetNext() {
+          i = 0;
+        }
+
+        var bindings = scopeTracker.bindings.get(scope);
+        var names = [].concat(_toConsumableArray(bindings.keys()));
+
+        /**
+         * 1. Iterate through the list of BindingIdentifiers
+         * 2. Rename each of them in-place
+         * 3. Update the scope tree.
+         */
+        for (var _i = 0; _i < names.length; _i++) {
+          var oldName = names[_i];
+          var binding = bindings.get(oldName);
+
+          // Names which should NOT be mangled
+          if (
+          // arguments - for non-strict mode
+          oldName === "arguments" ||
+          // labels
+          binding.path.isLabeledStatement() ||
+          // ClassDeclaration has binding in two scopes
+          //   1. The scope in which it is declared
+          //   2. The class's own scope
+          binding.path.isClassDeclaration() && binding.path === scope.path ||
+          // excluded
+          mangler.isExcluded(oldName) || (
+          // function names
+          mangler.keepFnName ? isFunction(binding.path) : false) || (
+          // class names
+          mangler.keepClassName ? isClass(binding.path) : false) ||
+          // named export
+          mangler.isExportedWithName(binding)) {
+            continue;
+          }
+
+          var next = void 0;
+          do {
+            next = getNext();
+          } while (!t.isValidIdentifier(next) || scopeTracker.hasBinding(scope, next) || scope.hasGlobal(next) || scopeTracker.hasReference(scope, next) || !scopeTracker.canUseInReferencedScopes(binding, next));
+
+          // Reset so variables which are removed can be reused
+          resetNext();
+
+          // Once we detected a valid `next` Identifier which could be used,
+          // call the renamer
+          mangler.rename(scope, binding, oldName, next);
+        }
+      }
+
+      /**
+       * The mangle function that traverses through all the Scopes in a BFS
+       * fashion - calls mangleScope
+       */
+
+    }, {
+      key: "mangle",
+      value: function mangle() {
+        var mangler = this;
+
+        bfsTraverse(this.program, {
+          Scopable(path) {
+            if (!path.isProgram() || mangler.topLevel) mangler.mangleScope(path.scope);
+          }
+        });
+      }
+
+      /**
+       * Given a NodePath, collects all the Identifiers which are BindingIdentifiers
+       * and replaces them with the new name
+       *
+       * For example,
+       *   var a = 1, { b } = c; // a and b are BindingIdentifiers
+       *
+       * @param {NodePath} path
+       * @param {String} oldName
+       * @param {String} newName
+       * @param {Function} predicate
+       */
+
+    }, {
+      key: "renameBindingIds",
+      value: function renameBindingIds(path, oldName, newName) {
+        var predicate = arguments.length > 3 && arguments[3] !== undefined ? arguments[3] : function () {
+          return true;
+        };
+
+        var bindingIds = path.getBindingIdentifierPaths(true, false);
+        for (var name in bindingIds) {
+          if (name !== oldName) continue;
+          var _iteratorNormalCompletion2 = true;
+          var _didIteratorError2 = false;
+          var _iteratorError2 = undefined;
+
+          try {
+            for (var _iterator2 = bindingIds[name][Symbol.iterator](), _step2; !(_iteratorNormalCompletion2 = (_step2 = _iterator2.next()).done); _iteratorNormalCompletion2 = true) {
+              var idPath = _step2.value;
+
+              if (predicate(idPath)) {
+                this.renamedNodes.add(idPath.node);
+                idPath.replaceWith(t.identifier(newName));
+                this.renamedNodes.add(idPath.node);
+              }
+            }
+          } catch (err) {
+            _didIteratorError2 = true;
+            _iteratorError2 = err;
+          } finally {
+            try {
+              if (!_iteratorNormalCompletion2 && _iterator2.return) {
+                _iterator2.return();
+              }
+            } finally {
+              if (_didIteratorError2) {
+                throw _iteratorError2;
+              }
+            }
+          }
+        }
+      }
+
+      /**
+       * The Renamer:
+       * Renames the following for one Binding in a Scope
+       *
+       * 1. Binding in that Scope
+       * 2. All the Binding's constant violations
+       * 3. All its References
+       * 4. Updates mangler.scopeTracker
+       * 5. Updates Babel's Scope tracking
+       *
+       * @param {Scope} scope
+       * @param {Binding} binding
+       * @param {String} oldName
+       * @param {String} newName
+       */
+
+    }, {
+      key: "rename",
+      value: function rename(scope, binding, oldName, newName) {
+        var mangler = this;
+        var scopeTracker = mangler.scopeTracker;
+
+        // rename at the declaration level
+
+        this.renameBindingIds(binding.path, oldName, newName, function (idPath) {
+          return idPath.node === binding.identifier;
+        });
+
+        // update mangler's ScopeTracker
+        scopeTracker.renameBinding(scope, oldName, newName);
+
+        // update all constant violations
+        var violations = binding.constantViolations;
+        for (var i = 0; i < violations.length; i++) {
+          if (violations[i].isLabeledStatement()) continue;
+
+          this.renameBindingIds(violations[i], oldName, newName);
+          scopeTracker.updateReference(violations[i].scope, binding, oldName, newName);
+        }
+
+        // update all referenced places
+        var refs = binding.referencePaths;
+        for (var _i2 = 0; _i2 < refs.length; _i2++) {
+          var path = refs[_i2];
+
+          var node = path.node;
+
+
+          if (!path.isIdentifier()) {
+            // Ideally, this should not happen
+            // it happens in these places now -
+            // case 1: Export Statements
+            // This is a bug in babel
+            // https://github.com/babel/babel/pull/3629
+            // case 2: Replacements in other plugins
+            // eg: https://github.com/babel/minify/issues/122
+            // replacement in dce from `x` to `!x` gives referencePath as `!x`
+            path.traverse({
+              ReferencedIdentifier(refPath) {
+                if (refPath.node.name !== oldName) {
+                  return;
+                }
+                var actualBinding = refPath.scope.getBinding(oldName);
+                if (actualBinding !== binding) {
+                  return;
+                }
+                mangler.renamedNodes.add(refPath.node);
+                refPath.replaceWith(t.identifier(newName));
+                mangler.renamedNodes.add(refPath.node);
+
+                scopeTracker.updateReference(refPath.scope, binding, oldName, newName);
+              }
+            });
+          } else if (!isLabelIdentifier(path)) {
+            if (path.node.name === oldName) {
+              mangler.renamedNodes.add(path.node);
+              path.replaceWith(t.identifier(newName));
+              mangler.renamedNodes.add(path.node);
+              scopeTracker.updateReference(path.scope, binding, oldName, newName);
+            } else if (mangler.renamedNodes.has(path.node)) {
+              // already renamed,
+              // just update the references
+              scopeTracker.updateReference(path.scope, binding, oldName, newName);
+            } else {
+              throw new Error(`Unexpected Rename Error: ` + `Trying to replace "${node.name}": from "${oldName}" to "${newName}". ` + `Please report it at ${newIssueUrl}`);
+            }
+          }
+          // else label identifier - silently ignore
+        }
+
+        // update babel's scope tracking
+        var bindings = scope.bindings;
+
+        bindings[newName] = binding;
+        delete bindings[oldName];
+      }
+    }]);
+
+    return Mangler;
+  }();
+
+  return {
+    name: "minify-mangle-names",
+    visitor: {
+      /**
+       * Mangler is run as a single pass. It's the same pattern as used in DCE
+       */
+      Program: {
+        exit(path) {
+          // If the source code is small then we're going to assume that the user
+          // is running on this on single files before bundling. Therefore we
+          // need to achieve as much determinisim and we will not do any frequency
+          // sorting on the character set. Currently the number is pretty arbitrary.
+          var shouldConsiderSource = path.getSource().length > 70000;
+
+          var charset = new Charset(shouldConsiderSource);
+
+          var mangler = new Mangler(charset, path, this.opts);
+          mangler.run();
+        }
+      }
+    }
+  };
+};
+
+// convert value to object
+function toObject(value) {
+  if (!Array.isArray(value)) {
+    return value;
+  }
+
+  var map = {};
+  for (var i = 0; i < value.length; i++) {
+    map[value[i]] = true;
+  }
+  return map;
+}
+
+// for keepFnName
+function isFunction(path) {
+  return path.isFunctionExpression() || path.isFunctionDeclaration();
+}
+
+// for keepClassName
+function isClass(path) {
+  return path.isClassExpression() || path.isClassDeclaration();
+}