Use recast to strip functions

README.md

@@ -15,16 +15,29 @@ Simple [Webpack](http://webpack.github.io/) loader to strip custom functions fro
 
 ## Usage
 
-In your client js source files:
+Before
 
 ```javascript
 
+// the following variable will be stubbed to a noop function
 var debug = require('debug')('MyFile');
 
 var makeFoo = function () {
-    // The following two lines of code will be stripped with our webpack loader
-    debug('makeFoo called');
-    debug('makeFoo args', arguments);
+    // The following line of code will be stripped with our webpack loader
+    debug('making Foo');
+    // This code would remain
+    return 'Foo';
+};
+
+```
+
+After
+
+```javascript
+
+var debug = function(){};
+
+var makeFoo = function () {
     // This code would remain
     return 'Foo';
 };
@@ -51,7 +64,7 @@ In your webpack config:
 {
     module: {
         loaders: [
-            { test: /\.js$/, loader: "strip-loader?strip[]=debug,strip[]=console.log" }
+            { test: /\.js$/, loader: "strip-loader?strip[]=debug,strip[]=assert" }
         ]
     }
 };
@@ -72,24 +85,6 @@ var webpackConfig = {
 };
 ```
 
-### Replace unused module
-
-So far we've removed the calls to the debug function, but your app still requires the `debug` module in the final bundle. Use the [`NormalModuleReplacementPlugin`](http://webpack.github.io/docs/list-of-plugins.html#normalmodulereplacementplugin) to replace it with an empty function:
-
-```javascript
-// webpack config
-{
-    plugins: [
-        new webpack.NormalModuleReplacementPlugin(/debug/, process.cwd() + '/emptyDebug.js'),
-    ]
-}
-
-// emptyDebug.js
-module.exports = function() { return new Function(); };
-```
-
-
-
 ## License
 
 This software is free to use under the Yahoo! Inc. BSD license.

lib/fix.js

@@ -0,0 +1,50 @@
+/* jshint ignore:start */
+// copied and modified from https://github.com/jshint/fixmyjs/blob/v2.0/lib/index.js
+// because they don't allow custom rules to be specified
+
+var fu = require('fu');
+var recast = require('recast');
+var traverse = require('./traverse');
+var SHEBANG = /^(\#\!.*)\n/;
+
+function getRules(options) {
+    return require('./rules').map(function (rule) {
+        return rule(options);
+    });
+}
+
+function fix(code, config) {
+    config = config || {};
+
+    var shebang = SHEBANG.exec(code);
+    var pureCode = code.replace(SHEBANG, '');
+    var ast;
+    try {
+        ast = recast.parse(pureCode);
+    } catch (e) {
+        if (e.message === 'AST contains no nodes at all?') {
+            return code;
+        }
+        throw e;
+    }
+    var rules = getRules(config);
+    var options = { wrapColumn: Infinity };
+
+    var modifiedTree = traverse(ast, function (node, parent) {
+        return fu.foldl(function (node, f) {
+            return node && f.hasOwnProperty(node.type)
+                ? f[node.type](node, parent)
+                : node;
+        }, rules, node);
+    });
+
+    var generatedCode = recast.print(modifiedTree, options).code;
+
+    return shebang === null
+        ? generatedCode
+        : [shebang[1], generatedCode].join('\n');
+}
+/* jshint ignore:end */
+
+module.exports = fix;
+

lib/index.js

@@ -6,20 +6,19 @@
 "use strict";
 
 var loaderUtils = require('loader-utils');
+var fix = require('./fix');
 
 function StripFnLoader(source) {
     var query = loaderUtils.parseQuery(this.query);
 
-    if (!query || !query.strip) return;
+    if (!query || !query.strip) {
+        this.callback(new Error('strip-loader: no functions provided for stripping'));
+    }
 
-    var toStrip = query.strip.join('|');
-
-    var regexPattern = new RegExp('\\n[ \\t]*(' + toStrip + ')\\([^\\);]+\\)[ \\t]*[;\\n]', 'g');
-
-    var transformed = source.replace(regexPattern, '\n');
-
-    this.callback(null, transformed);
+    var output = fix(source, {strip: query.strip});
+    this.callback(null, output);
 }
+
 module.exports = StripFnLoader;
 
 module.exports.loader = function () {

lib/rules/index.js

@@ -0,0 +1,4 @@
+module.exports = [
+    require('./stripFnCall'),
+    require('./stripFnDecl')
+];

lib/rules/stripFnCall.js

@@ -0,0 +1,17 @@
+module.exports = function (opts) {
+    return opts.strip ? {
+        ExpressionStatement: stripFnCalls.bind(stripFnCalls, opts.strip)
+    } : {};
+};
+
+function stripFnCalls (toStrip, node) {
+    if (!node.expression.type ||
+        node.expression.type !== 'CallExpression' ||
+        !node.expression.callee ||
+        node.expression.callee.type !== 'Identifier' ||
+        toStrip.indexOf(node.expression.callee.name) === -1) {
+        return node;
+    }
+
+    return [];
+}

lib/rules/stripFnDecl.js

@@ -0,0 +1,27 @@
+module.exports = function (opts) {
+    return opts.strip ? {
+        VariableDeclarator: stripFnDecl.bind(stripFnDecl, opts.strip)
+    } : {};
+};
+
+var recast = require('recast');
+var b = recast.types.builders;
+
+var emptyFnNode = b.functionExpression(
+    null,
+    [],
+    {
+        type: 'BlockStatement',
+        body: []
+    });
+
+function stripFnDecl (toStrip, node) {
+    if (node.id.type !== 'Identifier' ||
+        toStrip.indexOf(node.id.name) === -1) {
+        return node;
+    }
+
+    node.init = emptyFnNode;
+
+    return node;
+}

lib/traverse.js

@@ -0,0 +1,35 @@
+/* jshint ignore:start */
+/* globals toString */
+/* from https://github.com/jshint/fixmyjs/blob/v2.0/lib/traverse.js*/
+module.exports = traverse
+
+var fu = require('fu')
+
+function traverse(o, f, p) {
+  var k
+
+  function make(parent) {
+    return function (node) {
+      var next = traverse(node, f, parent)
+      next === node || (next._fixmyjs = 1)
+      return next
+    }
+  }
+
+  if (o === undefined) {
+    return o
+  }
+
+  for (k in o) {
+    var call = make(o)
+
+    if (toString.call(o[k]) == '[object Object]') {
+      o[k] = call(o[k])
+    } else if (Array.isArray(o[k])) {
+      o[k] = fu.concatMap(call, o[k])
+    }
+  }
+
+  return f(o, p)
+}
+/* jshint ignore:end */

package.json

@@ -5,7 +5,7 @@
   "main": "lib/index.js",
   "scripts": {
     "cover": "node node_modules/istanbul/lib/cli.js cover --dir artifacts -- ./node_modules/mocha/bin/_mocha tests/unit/ --recursive --reporter spec",
-    "lint": "./node_modules/.bin/jshint lib tests",
+    "lint": "./node_modules/.bin/jshint --exclude-path=.gitignore lib tests",
     "test": "mocha tests/unit --recursive --reporter spec"
   },
   "keywords": [
@@ -26,7 +26,9 @@
     "webpack": "^1.4.15"
   },
   "dependencies": {
-    "loader-utils": "^0.2.6"
+    "fu": "^0.1.0",
+    "loader-utils": "^0.2.6",
+    "recast": "^0.10.0"
   },
   "licenses": [
     {

tests/fixtures/app/index.js

@@ -2,11 +2,13 @@
  * Copyright 2015, Yahoo! Inc.
  * Copyrights licensed under the New BSD License. See the accompanying LICENSE file for terms.
  */
-
+var assert = require('chai').assert;
+var debug = require('debug')('Foo');
 var makeFoo = function (bar, baz) {
-    // The following 2 lines of code will be stripped with our webpack loader
-    console.log('some debug info');
+    // The following 3 lines of code will be stripped with our webpack loader
+    assert(bar, true);
     debug('better debug info');
+    debug('This is fancy debug: ' + (baz) + '.');
     // This code would remain
     return new Foo(bar, baz);
 };

tests/unit/index.js

@@ -32,20 +32,31 @@ var createWebpackConfigWithLoader = function (loaderOpt) {
 
 var createWebpackTest = function (done) {
     return function(err, stats) {
+        var statsJson = stats.toJson();
+        if (stats.hasErrors()) {
+            done(statsJson.errors[0]);
+        }
 
         expect(err).to.be.null();
         expect(stats.hasErrors()).to.be.false();
 
-        var statsJson = stats.toJson();
         expect(statsJson.errors).to.have.length(0);
 
         var originalSource = fs.readFileSync(cwd + '/index.js', {encoding: 'utf8'});
-        expect(originalSource).to.contain('console.log');
+        expect(originalSource).to.contain('assert');
         expect(originalSource).to.contain('debug');
 
         var strippedSource = statsJson.modules[0].source;
-        expect(strippedSource).to.not.contain('console.log');
-        expect(strippedSource).to.not.contain('debug');
+        if (strippedSource.match(/assert/g)) {
+            expect(strippedSource.match(/assert/g)).to.have.length.of.at.most(1);
+        } else {
+            expect(strippedSource).to.not.contain('assert');
+        }
+        if (strippedSource.match(/debug/g)) {
+            expect(strippedSource.match(/debug/g)).to.have.length.of.at.most(1);
+        } else {
+            expect(strippedSource).to.not.contain('debug');
+        }
 
         done(err);
     };
@@ -56,14 +67,14 @@ describe('integration', function () {
     describe('webpack', function () {
         it('should work with loader query params', function (done) {
             webpack(
-                createWebpackConfigWithLoader(loaderLibPath + '?strip[]=console.log,strip[]=debug'),
+                createWebpackConfigWithLoader(loaderLibPath + '?strip[]=assert,strip[]=debug'),
                 createWebpackTest(done)
             );
         });
 
         it('should work with loader used as library', function (done) {
             webpack(
-                createWebpackConfigWithLoader(loaderLib.loader('console.log', 'debug')),
+                createWebpackConfigWithLoader(loaderLib.loader('assert', 'debug')),
                 createWebpackTest(done)
             );
         });