remove isDynamic checks and always execute those expressions **once**

lib/6to5/transformation/transformers/es6-classes.js

@@ -89,7 +89,7 @@ Class.prototype.run = function () {
     this.closure = true;
 
     // so we're only evaluating it once
-    var superRef = t.getUid(superName, this.file);
+    var superRef = this.scope.generateUidBasedOnNode(superName, this.file);
     body.unshift(t.variableDeclaration("var", [
       t.variableDeclarator(superRef, superName)
     ]));

lib/6to5/transformation/transformers/es6-computed-property-names.js

@@ -1,6 +1,6 @@
 var t = require("../../types");
 
-exports.ObjectExpression = function (node, parent, file) {
+exports.ObjectExpression = function (node, parent, file, scope) {
   var hasComputed = false;
   var prop;
   var key;
@@ -13,7 +13,7 @@ exports.ObjectExpression = function (node, parent, file) {
 
   if (!hasComputed) return;
 
-  var objId = t.getUid(parent, file);
+  var objId = scope.generateUidBasedOnNode(parent, file);
 
   var body = [];
   var container = t.functionExpression(null, [], t.blockStatement(body));

lib/6to5/transformation/transformers/es6-destructuring.js

@@ -75,7 +75,7 @@ var pushArrayPattern = function (opts, nodes, pattern, parentId) {
 
   var toArray = opts.file.toArray(parentId, !hasSpreadElement && pattern.elements.length);
 
-  var _parentId = t.getUid(parentId, opts.file, opts.scope);
+  var _parentId = opts.scope.generateUidBasedOnNode(parentId, opts.file);
   nodes.push(t.variableDeclaration("var", [
     t.variableDeclarator(_parentId, toArray)
   ]));
@@ -113,7 +113,7 @@ var pushPattern = function (opts) {
   var scope = opts.scope;
 
   if (!t.isMemberExpression(parentId) && !t.isIdentifier(parentId)) {
-    var key = t.getUid(parentId, file, scope);
+    var key = scope.generateUidBasedOnNode(parentId, file);
 
     nodes.push(t.variableDeclaration("var", [
       t.variableDeclarator(key, parentId)

lib/6to5/transformation/transformers/es6-property-method-assignment.js

@@ -7,7 +7,7 @@ exports.Property = function (node, parent, file, scope) {
 
   node.method = false;
 
-  var key = t.toComputedPropertyKey(node);
+  var key = t.toComputedKey(node, node.key);
   if (!t.isLiteral(key)) return; // we can't set a function id with this
 
   var id = t.toIdentifier(key.value);
@@ -46,7 +46,7 @@ exports.Property = function (node, parent, file, scope) {
   }
 };
 
-exports.ObjectExpression = function (node, parent, file) {
+exports.ObjectExpression = function (node, parent, file, scope) {
   var mutatorMap = {};
   var hasAny = false;
 
@@ -63,7 +63,7 @@ exports.ObjectExpression = function (node, parent, file) {
   if (!hasAny) return;
 
   if (node.properties.length) {
-    var objId = t.getUid(parent, file);
+    var objId = scope.generateUidBasedOnNode(parent, file);
 
     return util.template("object-define-properties-closure", {
       KEY: objId,

lib/6to5/transformation/transformers/es6-spread.js

@@ -77,16 +77,13 @@ exports.CallExpression = function (node, parent, file, scope) {
   }
 
   var callee = node.callee;
-  var temp;
 
   if (t.isMemberExpression(callee)) {
-    contextLiteral = callee.object;
-
-    if (t.isDynamic(contextLiteral)) {
-      temp = contextLiteral = scope.generateTemp(file);
+    var temp = scope.generateTempBasedOnNode(callee.object, file);
+    if (temp) {
       callee.object = t.assignmentExpression("=", temp, callee.object);
+      contextLiteral = temp;
     }
-
     t.appendToMemberExpression(callee, t.identifier("apply"));
   } else {
     node.callee = t.memberExpression(node.callee, t.identifier("apply"));

lib/6to5/transformation/transformers/es7-abstract-references.js

@@ -30,10 +30,8 @@ exports.AssignmentExpression = function (node, parent, file, scope) {
 
   // we need to return `node.right`
   if (!t.isExpressionStatement(parent)) {
-    // `node.right` isn't a simple identifier so we need to reference it
-    if (t.isDynamic(value)) {
-      temp = value = scope.generateTemp(file);
-    }
+    temp = scope.generateTempBasedOnNode(node.right, file);
+    if (temp) value = temp;
   }
 
   if (node.operator !== "=") {
@@ -80,11 +78,7 @@ exports.CallExpression = function (node, parent, file, scope) {
   var callee = node.callee;
   if (!t.isVirtualPropertyExpression(callee)) return;
 
-  var temp;
-  if (t.isDynamic(callee.object)) {
-    // we need to save `callee.object` so we can call it again
-    temp = scope.generateTemp(file);
-  }
+  var temp = scope.generateTempBasedOnNode(callee.object, file);
 
   var call = util.template("abstract-expression-call", {
     PROPERTY: callee.property,

lib/6to5/transformation/transformers/es7-array-comprehension.js

@@ -5,7 +5,7 @@ var t        = require("../../types");
 exports.experimental = true;
 
 var build = function (node, parent, file, scope) {
-  var uid = t.getUid(parent, file, scope);
+  var uid = scope.generateUidBasedOnNode(parent, file);
 
   var container = util.template("array-comprehension-container", {
     KEY: uid

lib/6to5/transformation/transformers/playground-memoization-operator.js

@@ -10,7 +10,7 @@ var getPropRef = function (nodes, prop, file, scope) {
   if (t.isIdentifier(prop)) {
     return t.literal(prop.name);
   } else {
-    var temp = t.getUid(prop, file, scope);
+    var temp = scope.generateUidBasedOnNode(prop, file);
     nodes.push(t.variableDeclaration("var", [
       t.variableDeclarator(temp, prop)
     ]));
@@ -19,15 +19,11 @@ var getPropRef = function (nodes, prop, file, scope) {
 };
 
 var getObjRef = function (nodes, obj, file, scope) {
-  if (t.isDynamic(obj)) {
-    var temp = t.getUid(obj, file, scope);
-    nodes.push(t.variableDeclaration("var", [
-      t.variableDeclarator(temp, obj)
-    ]));
-    return temp;
-  } else {
-    return obj;
-  }
+  var temp = scope.generateUidBasedOnNode(obj, file);
+  nodes.push(t.variableDeclaration("var", [
+    t.variableDeclarator(temp, obj)
+  ]));
+  return temp;
 };
 
 var buildHasOwn = function (obj, prop, file) {

lib/6to5/transformation/transformers/playground-method-binding.js

@@ -5,10 +5,8 @@ exports.BindMemberExpression = function (node, parent, file, scope) {
   var object = node.object;
   var prop   = node.property;
 
-  var temp;
-  if (t.isDynamic(object)) {
-    temp = object = scope.generateTemp(file);
-  }
+  var temp = scope.generateTempBasedOnNode(node.object, file);
+  if (temp) object = temp;
 
   var call = t.callExpression(
     t.memberExpression(t.memberExpression(object, prop), t.identifier("bind")),
@@ -33,16 +31,12 @@ exports.BindFunctionExpression = function (node, parent, file, scope) {
     ]));
   };
 
-  if (_.find(node.arguments, t.isDynamic)) {
-    var temp = scope.generateTemp(file, "args");
+  var temp = scope.generateTemp(file, "args");
 
-    return t.sequenceExpression([
-      t.assignmentExpression("=", temp, t.arrayExpression(node.arguments)),
-      buildCall(node.arguments.map(function (node, i) {
-        return t.memberExpression(temp, t.literal(i), true);
-      }))
-    ]);
-  } else {
-    return buildCall(node.arguments);
-  }
+  return t.sequenceExpression([
+    t.assignmentExpression("=", temp, t.arrayExpression(node.arguments)),
+    buildCall(node.arguments.map(function (node, i) {
+      return t.memberExpression(temp, t.literal(i), true);
+    }))
+  ]);
 };

lib/6to5/traverse/scope.js

@@ -31,6 +31,13 @@ Scope.add = function (node, references) {
   _.defaults(references, t.getIds(node, true));
 };
 
+/**
+ * Description
+ *
+ * @param {File} file
+ * @param {String} [name="temp"]
+ */
+
 Scope.prototype.generateTemp = function (file, name) {
   var id = file.generateUidIdentifier(name || "temp", this);
   this.push({
@@ -40,6 +47,83 @@ Scope.prototype.generateTemp = function (file, name) {
   return id;
 };
 
+/*
+ * Description
+ *
+ * @param {Object} parent
+ * @param {File} file
+ * @param {Scope} scope
+ * @returns {Object}
+ */
+
+Scope.prototype.generateUidBasedOnNode = function (parent, file) {
+  var node = parent;
+
+  if (t.isAssignmentExpression(parent)) {
+    node = parent.left;
+  } else if (t.isVariableDeclarator(parent)) {
+    node = parent.id;
+  }
+
+  var id = "ref";
+
+  if (t.isProperty(node)) {
+    node = node.key;
+  }
+
+  if (t.isIdentifier(node)) {
+    id = node.name;
+  } else if (t.isLiteral(node)) {
+    id = node.value;
+  } else if (t.isMemberExpression(node)) {
+    var parts = [];
+
+    var add = function (node) {
+      if (t.isMemberExpression(node)) {
+        add(node.object);
+        add(node.property);
+      } else if (t.isIdentifier(node)) {
+        parts.push(node.name);
+      } else if (t.isLiteral(node)) {
+        parts.push(node.value);
+      }
+    };
+
+    add(node);
+
+    id = parts.join("$");
+  }
+
+  id = id.replace(/^_/, "");
+
+  return file.generateUidIdentifier(id, this);
+};
+
+/**
+ * Description
+ *
+ * @param {Object} node
+ * @param {File} file
+ * @returns {Object}
+ */
+
+Scope.prototype.generateTempBasedOnNode = function (node, file) {
+  if (!t.isIdentifier(node) && !t.isMemberExpression(node)) {
+    throw new TypeError("Invalid node type " + JSON.stringify(node.type) + " passed to Scope.prototype.generateTempBasedOnNode");
+  }
+
+  if (t.isIdentifier(node) && this.has(node.name, true)) {
+    return null;
+  }
+
+  var id = this.generateUidBasedOnNode(node, file);
+  this.push({
+    key: id.name,
+    id: id
+  });
+  return id;
+};
+
 Scope.prototype.getInfo = function () {
   var block = this.block;
   if (block._scopeInfo) return block._scopeInfo;
@@ -123,6 +207,12 @@ Scope.prototype.getInfo = function () {
   return info;
 };
 
+/**
+ * Description
+ *
+ * @param {Object} opts
+ */
+
 Scope.prototype.push = function (opts) {
   var block = this.block;
 
@@ -143,33 +233,84 @@ Scope.prototype.push = function (opts) {
   }
 };
 
+/**
+ * Description
+ *
+ * @param {Object} node
+ */
+
 Scope.prototype.add = function (node) {
   Scope.add(node, this.references);
 };
 
+/**
+ * Description
+ *
+ * @param {String} [id]
+ * @param {Boolean} [decl]
+ */
+
 Scope.prototype.get = function (id, decl) {
   return id && (this.getOwn(id, decl) || this.parentGet(id, decl));
 };
 
+/**
+ * Description
+ *
+ * @param {String} [id]
+ * @param {Boolean} [decl]
+ */
+
 Scope.prototype.getOwn = function (id, decl) {
   var refs = this.references;
   if (decl) refs = this.declarations;
   return _.has(refs, id) && refs[id];
 };
 
+/**
+ * Description
+ *
+ * @param {String} [id]
+ * @param {Boolean} [decl]
+ */
+
 Scope.prototype.parentGet = function (id, decl) {
   return this.parent && this.parent.get(id, decl);
 };
 
+/**
+ * Description
+ *
+ * @param {String} [id]
+ * @param {Boolean} [decl]
+ * @returns {Boolean}
+ */
+
 Scope.prototype.has = function (id, decl) {
   return (id && (this.hasOwn(id, decl) || this.parentHas(id, decl))) ||
          _.contains(Scope.defaultDeclarations, id);
 };
 
+/**
+ * Description
+ *
+ * @param {String} [id]
+ * @param {Boolean} [decl]
+ * @returns {Boolean}
+ */
+
 Scope.prototype.hasOwn = function (id, decl) {
   return !!this.getOwn(id, decl);
 };
 
+/**
+ * Description
+ *
+ * @param {String} [id]
+ * @param {Boolean} [decl]
+ * @returns {Boolean}
+ */
+
 Scope.prototype.parentHas = function (id, decl) {
   return this.parent && this.parent.has(id, decl);
 };

lib/6to5/types/index.js

@@ -71,9 +71,8 @@ _.each(t.FLIPPED_ALIAS_KEYS, function (types, type) {
  * @returns {Object}
  */
 
-t.toComputedPropertyKey = function (prop) {
-  var key = prop.key;
-  if (!prop.computed) {
+t.toComputedKey = function (node, key) {
+  if (!node.computed) {
     if (t.isIdentifier(key)) key = t.literal(key.name);
   }
   return key;
@@ -126,6 +125,10 @@ t.toSequenceExpression = function (nodes, scope) {
     }
   });
 
+  if (exprs.length === 1) {
+    return exprs[0]
+  }
+
   return t.sequenceExpression(exprs);
 };
 
@@ -174,25 +177,6 @@ t.prependToMemberExpression = function (member, append) {
   return member;
 };
 
-/*
- * Description
- *
- * @param {Object} node
- * @returns {Boolean}
- */
-
-t.isDynamic = function (node) {
-  if (t.isExpressionStatement(node)) {
-    return t.isDynamic(node.expression);
-  } else if (t.isIdentifier(node) || t.isLiteral(node) || t.isThisExpression(node)) {
-    return false;
-  } else if (t.isMemberExpression(node)) {
-    return t.isDynamic(node.object) || t.isDynamic(node.property);
-  } else {
-    return true;
-  }
-};
-
 /**
  * Description
  *
@@ -341,58 +325,6 @@ t.toBlock = function (node, parent) {
   return t.blockStatement(node);
 };
 
-/*
- * Description
- *
- * @param {Object} parent
- * @param {File} file
- * @param {Scope} scope
- * @returns {Object}
- */
-
-t.getUid = function (parent, file, scope) {
-  var node = parent;
-
-  if (t.isAssignmentExpression(parent)) {
-    node = parent.left;
-  } else if (t.isVariableDeclarator(parent)) {
-    node = parent.id;
-  }
-
-  var id = "ref";
-
-  if (t.isProperty(node)) {
-    node = node.key;
-  }
-
-  if (t.isIdentifier(node)) {
-    id = node.name;
-  } else if (t.isLiteral(node)) {
-    id = node.value;
-  } else if (t.isMemberExpression(node)) {
-    var parts = [];
-
-    var add = function (node) {
-      if (t.isMemberExpression(node)) {
-        add(node.object);
-        add(node.property);
-      } else if (t.isIdentifier(node)) {
-        parts.push(node.name);
-      } else if (t.isLiteral(node)) {
-        parts.push(node.value);
-      }
-    };
-
-    add(node);
-
-    id = parts.join("$");
-  }
-
-  id = id.replace(/^_/, "");
-
-  return file.generateUidIdentifier(id, scope);
-};
-
 /**
  * Description
  *