Cleanup build script comments and fix Closure Compiler bugs.

Former-commit-id: 84771ac79d6cfd7ec3b0d29586edf58d617d5577

build.js

@@ -12,14 +12,14 @@
   /** The current working directory */
   var cwd = process.cwd();
 
-  /** Shortcut to native `Array.prototype` */
-  var ArrayProto = Array.prototype;
+  /** Used for array method references */
+  var arrayRef = [];
 
   /** Shortcut used to push arrays of values to an array */
-  var push = ArrayProto.push;
+  var push = arrayRef.push;
 
   /** Shortcut used to convert array-like objects to arrays */
-  var slice = ArrayProto.slice;
+  var slice = arrayRef.slice;
 
   /** Shortcut to the `stdout` object */
   var stdout = process.stdout;
@@ -792,7 +792,7 @@
   /*--------------------------------------------------------------------------*/
 
   /**
-   * Creates a debug and minified build, executing the `callback` for each.
+   * Creates a debug and/or minified build, executing the `callback` for each.
    * The `callback` is invoked with two arguments; (filePath, outputSource).
    *
    * Note: For a list of commands see `displayHelp()` or run `lodash --help`.
@@ -1065,7 +1065,7 @@
           '  function difference(array) {',
           '    var index = -1,',
           '        length = array.length,',
-          '        flattened = concat.apply(ArrayProto, arguments),',
+          '        flattened = concat.apply(arrayRef, arguments),',
           '        result = [];',
           '',
           '    while (++index < length) {',
@@ -1121,7 +1121,7 @@
         // replace `_.omit`
         source = source.replace(/^( +)function omit[\s\S]+?\n\1}/m, [
           '  function omit(object) {',
-          '    var props = concat.apply(ArrayProto, arguments),',
+          '    var props = concat.apply(arrayRef, arguments),',
           '        result = {};',
           '',
           '    forIn(object, function(value, key) {',
@@ -1137,7 +1137,7 @@
         source = source.replace(/^( +)function pick[\s\S]+?\n\1}/m, [
           '  function pick(object) {',
           '    var index = 0,',
-          '        props = concat.apply(ArrayProto, arguments),',
+          '        props = concat.apply(arrayRef, arguments),',
           '        length = props.length,',
           '        result = {};',
           '',
@@ -1647,10 +1647,6 @@
         'isTemplate': isTemplate,
         'outputPath': outputPath,
         'onComplete': function(source) {
-          // correct overly aggressive Closure Compiler minification
-          if (!isTemplate) {
-            source = source.replace(/prototype\s*=\s*{\s*valueOf\s*:\s*1\s*}/, 'prototype={valueOf:1,y:1}');
-          }
           // inject "use strict" directive
           if (isStrict) {
             source = source.replace(/^([\s\S]*?function[^{]+{)([^'"])/, '$1"use strict";$2');

build/minify.js

@@ -19,7 +19,7 @@
       postprocess = require('./post-compile'),
       uglifyJS = require('../vendor/uglifyjs/uglify-js');
 
-  /** Closure Compiler command-line options */
+  /** The Closure Compiler command-line options */
   var closureOptions = [
     '--compilation_level=ADVANCED_OPTIMIZATIONS',
     '--warning_level=QUIET'
@@ -135,7 +135,7 @@
         return value.replace(/^(--compilation_level)=.+$/, '$1=SIMPLE_OPTIMIZATIONS');
       });
     }
-    // the standard error stream, standard output stream, and Closure Compiler process
+    // the standard error stream, standard output stream, and the Closure Compiler process
     var error = '',
         output = '',
         compiler = spawn('java', ['-jar', closurePath].concat(options));
@@ -348,7 +348,7 @@
         uglified = this.uglified;
 
     // select the smallest gzipped file and use its minified counterpart as the
-    // official minified release (ties go to Closure Compiler)
+    // official minified release (ties go to the Closure Compiler)
     var min = Math.min(compiled.gzip.length, hybrid.gzip.length, uglified.gzip.length);
 
     // pass the minified source to the minify instances "onComplete" callback

build/post-compile.js

@@ -26,9 +26,17 @@
    * @returns {String} Returns the processed source.
    */
   function postprocess(source) {
-    // move vars exposed by Closure Compiler into the IIFE
+    // move vars exposed by the Closure Compiler into the IIFE
     source = source.replace(/^((?:(['"])use strict\2;)?(?:var (?:[a-z]+=(?:!0|!1|null)[,;])+)?)([\s\S]*?function[^)]+\){)/, '$3$1');
 
+    // avoid bugs with the Closure Compiler
+    source = source
+      // correct overly aggressive Closure Compiler minification
+      .replace(/prototype\s*=\s*{\s*valueOf\s*:\s*1\s*}/, 'prototype={valueOf:1,y:1}')
+      // restore `arrayRef` and `objectRef` values modified by pre-compile.js
+      .replace(/= *Array.prototype/, '=[]')
+      .replace(/= *Object.prototype/, '={}');
+
     // unescape properties (i.e. foo["bar"] => foo.bar)
     source = source.replace(/(\w)\["([^."]+)"\]/g, function(match, left, right) {
       return /\W/.test(right) ? match : (left + '.' + right);

build/pre-compile.js

@@ -206,7 +206,7 @@
     source || (source = '');
     options || (options = {});
 
-    // remove unrecognized JSDoc tags so Closure Compiler won't complain
+    // remove unrecognized JSDoc tags so the Closure Compiler won't complain
     source = source.replace(/@(?:alias|category)\b.*/g, '');
 
     if (options.isTemplate) {
@@ -216,7 +216,12 @@
     // remove copyright to add later in post-compile.js
     source = source.replace(/\/\*![\s\S]+?\*\//, '');
 
-    // add brackets to whitelisted properties so Closure Compiler won't mung them
+    // replace `arrayRef` and `objectRef` values to avoid a bug in the Closure Compiler
+    source = source
+      .replace(/(arrayRef *= *)\[\]/, '$1Array.prototype')
+      .replace(/(objectRef *= *)\{\}/, '$1Object.prototype');
+
+    // add brackets to whitelisted properties so the Closure Compiler won't mung them
     // http://code.google.com/closure/compiler/docs/api-tutorial3.html#export
     source = source.replace(RegExp('\\.(' + propWhitelist.join('|') + ')\\b', 'g'), "['$1']");
 
@@ -314,7 +319,7 @@
           isIteratorTemplate = /var iteratorTemplate\b/.test(snippet),
           modified = snippet;
 
-      // add brackets to whitelisted properties so Closure Compiler won't mung them
+      // add brackets to whitelisted properties so the Closure Compiler won't mung them
       modified = modified.replace(RegExp('\\.(' + iteratorOptions.join('|') + ')\\b', 'g'), "['$1']");
 
       if (isCreateIterator) {