add Infinity/NaN, string/number member expressions/calls and Math calls static evaluation

src/babel/transformation/transformers/index.js

@@ -7,14 +7,14 @@ export default {
   "minification.removeDebugger":           require("./minification/remove-debugger"),
   "minification.removeConsole":            require("./minification/remove-console"),
   "utility.inlineEnvironmentVariables":    require("./utility/inline-environment-variables"),
-  "minification.inlineExpressions":        require("./minification/inline-expressions"),
-  "minification.deadCodeElimination":      require("./minification/dead-code-elimination"),
+  "minification.constantFolding":          require("./minification/constant-folding"),
   _modules:                                require("./internal/modules"),
   "spec.functionName":                     require("./spec/function-name"),
 
   //- builtin-basic
   // this is where the bulk of the ES6 transformations take place, none of them require traversal state
   // so they can all be concatenated together for performance
+  "minification.deadCodeElimination":      require("./minification/dead-code-elimination"),
   "es7.classProperties":                   require("./es7/class-properties"),
   "es7.trailingFunctionCommas":            require("./es7/trailing-function-commas"),
   "es7.asyncFunctions":                    require("./es7/async-functions"),

src/babel/traversal/path/evaluation.js

@@ -1,5 +1,7 @@
 /* eslint eqeqeq: 0 */
 
+const VALID_CALLEES = ["String", "Number", "Math"];
+
 /**
  * Walk the input `node` and statically evaluate if it's truthy.
  *
@@ -74,8 +76,28 @@ export function evaluate(): { confident: boolean; value: any } {
       }
     }
 
-    if (path.isIdentifier({ name: "undefined" })) {
-      return undefined;
+    if (path.isIdentifier() && !path.scope.hasBinding(node.name, true)) {
+      if (node.name === "undefined") {
+        return undefined;
+      } else if (node.name === "Infinity") {
+        return Infinity;
+      } else if (node.name === "NaN") {
+        return NaN;
+      }
+    }
+
+    // "foo".length
+    if (path.isMemberExpression() && !path.parentPath.isCallExpression({ callee: node })) {
+      let property = path.get("property");
+      let object = path.get("object");
+
+      if (object.isLiteral() && property.isIdentifier()) {
+        let value = object.node.value;
+        let type = typeof value;
+        if (type === "number" || type === "string") {
+          return value[property.node.name];
+        }
+      }
     }
 
     if ((path.isIdentifier() || path.isMemberExpression()) && path.isReferenced()) {
@@ -134,6 +156,44 @@ export function evaluate(): { confident: boolean; value: any } {
       }
     }
 
+    if (path.isCallExpression()) {
+      var callee = path.get("callee");
+      var context;
+      var func;
+
+      // Number(1);
+      if (callee.isIdentifier() && !path.scope.getBinding(callee.node.name, true) && VALID_CALLEES.indexOf(callee.node.name) >= 0) {
+        func = global[node.callee.name];
+      }
+
+      if (callee.isMemberExpression()) {
+        let object = callee.get("object");
+        var property = callee.get("property");
+
+        // Math.min(1, 2)
+        if (object.isIdentifier() && property.isIdentifier() && VALID_CALLEES.indexOf(object.node.name) >= 0) {
+          context = global[object.node.name];
+          func = context[property.node.name];
+        }
+
+        // "abc".charCodeAt(4)
+        if (object.isLiteral() && property.isIdentifier()) {
+          let type = typeof object.node.value;
+          if (type === "string" || type === "number") {
+            context = object.node.value;
+            func = context[property.node.name];
+          }
+        }
+      }
+
+      if (func) {
+        var args = path.get("arguments").map(evaluate);
+        if (!confident) return;
+
+        return func.apply(context, args);
+      }
+    }
+
     confident = false;
   }
 }

src/babel/traversal/scope/index.js

@@ -77,9 +77,19 @@ var collectorVisitor = {
   },
 
   BlockScoped(node, parent, scope) {
+    if (this.isFunctionDeclaration()) return;
     if (scope.path === this) scope = scope.parent;
     scope.getBlockParent().registerDeclaration(this);
-  }
+  },
+
+  Block(node, parent, scope) {
+    var paths = this.get("body");
+    for (var path of (paths: Array)) {
+      if (path.isFunctionDeclaration()) {
+        scope.getBlockParent().registerDeclaration(path);
+      }
+    }
+  },
 };
 
 var renameVisitor = {
@@ -132,7 +142,13 @@ export default class Scope {
   }
 
   static globals = flatten([globals.builtin, globals.browser, globals.node].map(Object.keys));
-  static contextVariables = ["this", "arguments", "super", "undefined"];
+
+  static contextVariables = [
+    "arguments",
+    "undefined",
+    "Infinity",
+    "NaN"
+  ];
 
   /**
    * Description
@@ -539,14 +555,29 @@ export default class Scope {
    * Description
    */
 
-  isPure(node, constantsOnly) {
+  isPure(node, constantsOnly?: boolean) {
     if (t.isIdentifier(node)) {
-      var bindingInfo = this.getBinding(node.name);
-      return !!bindingInfo && (!constantsOnly || (constantsOnly && bindingInfo.constant));
+      var binding = this.getBinding(node.name);
+      if (!binding) return false;
+      if (constantsOnly) return binding.constant;
+      return true;
     } else if (t.isClass(node)) {
-      return !node.superClass;
+      return !node.superClass || this.isPure(node.superClass, constantsOnly);
     } else if (t.isBinary(node)) {
       return this.isPure(node.left, constantsOnly) && this.isPure(node.right, constantsOnly);
+    } else if (t.isArrayExpression(node)) {
+      for (var elem of (node.elements: Array)) {
+        if (!this.isPure(elem, constantsOnly)) return false;
+      }
+      return true;
+    } else if (t.isObjectExpression(node)) {
+      for (var prop of (node.properties: Array)) {
+        if (!this.isPure(prop, constantsOnly)) return false;
+      }
+      return true;
+    } else if (t.isProperty(node)) {
+      if (node.computed && !t.isPure(node.key, constantsOnly)) return false;
+      return t.isPure(node.value, constantsOnly);
     } else {
       return t.isPure(node);
     }
@@ -821,13 +852,13 @@ export default class Scope {
    * Description
    */
 
-  hasBinding(name: string) {
+  hasBinding(name: string, noGlobals?) {
     if (!name) return false;
     if (this.hasOwnBinding(name)) return true;
-    if (this.parentHasBinding(name)) return true;
+    if (this.parentHasBinding(name, noGlobals)) return true;
     if (this.hasUid(name)) return true;
-    if (includes(Scope.globals, name)) return true;
-    if (includes(Scope.contextVariables, name)) return true;
+    if (!noGlobals && includes(Scope.globals, name)) return true;
+    if (!noGlobals && includes(Scope.contextVariables, name)) return true;
     return false;
   }
 
@@ -835,8 +866,8 @@ export default class Scope {
    * Description
    */
 
-  parentHasBinding(name: string) {
-    return this.parent && this.parent.hasBinding(name);
+  parentHasBinding(name: string, noGlobals?) {
+    return this.parent && this.parent.hasBinding(name, noGlobals);
   }
 
   /**

src/babel/types/alias-keys.json

@@ -8,10 +8,10 @@
   "LabeledStatement":         ["Statement"],
   "VariableDeclaration":      ["Statement", "Declaration"],
 
-  "BreakStatement":           ["Statement", "Terminatorless"],
-  "ContinueStatement":        ["Statement", "Terminatorless"],
-  "ReturnStatement":          ["Statement", "Terminatorless"],
-  "ThrowStatement":           ["Statement", "Terminatorless"],
+  "BreakStatement":           ["Statement", "Terminatorless", "CompletionStatement"],
+  "ContinueStatement":        ["Statement", "Terminatorless", "CompletionStatement"],
+  "ReturnStatement":          ["Statement", "Terminatorless", "CompletionStatement"],
+  "ThrowStatement":           ["Statement", "Terminatorless", "CompletionStatement"],
 
   "DoWhileStatement":         ["Statement", "BlockParent", "Loop", "While", "Scopable"],
   "WhileStatement":           ["Statement", "BlockParent", "Loop", "While", "Scopable"],
@@ -32,8 +32,8 @@
   "FunctionDeclaration":     ["Scopable", "Function", "Func", "BlockParent", "FunctionParent", "Statement", "Pure", "Declaration"],
   "FunctionExpression":      ["Scopable", "Function", "Func", "BlockParent", "FunctionParent", "Expression", "Pure"],
 
-  "BlockStatement": ["Scopable", "BlockParent", "Statement"],
-  "Program":        ["Scopable", "BlockParent", "FunctionParent"],
+  "BlockStatement": ["Scopable", "BlockParent", "Block", "Statement"],
+  "Program":        ["Scopable", "BlockParent", "Block", "FunctionParent"],
   "CatchClause":    ["Scopable"],
 
   "LogicalExpression": ["Binary", "Expression"],