ddd-jquery/_transforms/deamdify.js

de-bowerified, de-amdified, de-gruntified... jQuery.

/*
(The MIT License)

Copyright (c) 2013 Jared Hanson

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

/**
 * Module dependencies.
 */
var through = require('through')
  , esprima = require('esprima')
  , estraverse = require('estraverse')
  , escodegen = require('escodegen')
  , util = require('util');


/**
 * Transform AMD to CommonJS.
 *
 * This transform translates AMD modules into CommonJS modules.  AMD modules
 * are defined by calling the `define` function that is available as a free
 * or global variable.  The transform translates that call into traditional
 * CommonJS require statements.  Any value returned from the factory function
 * is assigned to `module.exports`.
 *
 * After the transform is complete, Browserify will be able to parse and
 * bundle the module as if it were a Node.js module.
 *
 * @param {String} file
 * @return {Stream}
 * @api public
 */
module.exports = function (file) {
  var data = '';
  
  var stream = through(write, end);
  return stream;
  
  function write(buf) { data += buf }
  function end() {

    console.log('[deamdify]', file);

    var ast = esprima.parse(data)
      , tast
      , isAMD = false;
    
    //console.log('-- ORIGINAL AST --');
    //console.log(util.inspect(ast, false, null));
    //console.log('------------------');
    
    // TODO: Ensure that define is a free variable.
    // TODO: Implement support for amdWeb UMD modules.
    
    estraverse.replace(ast, {
      enter: function(node) {
        if (isDefine(node)) {
          var parents = this.parents();
          
          // Check that this module is an AMD module, as evidenced by invoking
          // `define` at the top-level.  Any CommonJS or UMD modules are pass
          // through unmodified.
          if (parents.length == 2 && parents[0].type == 'Program' && parents[1].type == 'ExpressionStatement') {
            isAMD = true;
          }
        }
      },
      leave: function(node) {
        if (isDefine(node)) {
          if (node.arguments.length == 1 && node.arguments[0].type == 'FunctionExpression') {
            var factory = node.arguments[0];
            
            if (factory.params.length == 0) {
              tast = createProgram(factory.body.body);
              this.break();
            } else if (factory.params.length > 0) {
              // simplified CommonJS wrapper
              tast = createProgram(factory.body.body);
              this.break();
            }
          } else if (node.arguments.length == 1 && node.arguments[0].type == 'ObjectExpression') {
            // object literal
            var obj = node.arguments[0];
            
            tast = createModuleExport(obj);
            this.break();
          } else if (node.arguments.length == 1 && node.arguments[0].type == 'ArrayExpression') {

            // define(['dep1/file'])
            // Found in the jQuery source.
            var dependencies = node.arguments[0];
            var reqs = dependencies.elements.map(function(el) {
              return createRequireExpression(el.value);
            });

            if (reqs) {
              tast = createProgram(reqs);
            }

            this.break();

          } else if (node.arguments.length == 2 && node.arguments[0].type == 'ArrayExpression' && node.arguments[1].type == 'FunctionExpression') {
            var dependencies = node.arguments[0]
              , factory = node.arguments[1];
            
            var ids = dependencies.elements.map(function(el) { return el.value });
            var vars = factory.params.map(function(el) { return el.name });

            // Backfill in the event that there are not enough defined
            // callback args (named dependencies) to match dependency
            // paths:
            //   define(['a/hey', 'a/what'], function(hey) {});
            while (vars.length < ids.length) {
              vars.push('__unnameddep__');
            }

            var reqs = createRequires(ids, vars);
            if (reqs) {
              tast = createProgram([reqs].concat(factory.body.body));
            } else {
              tast = createProgram(factory.body.body);
            }
            this.break();
          } else if (node.arguments.length == 3 && node.arguments[0].type == 'Literal' && node.arguments[1].type == 'ArrayExpression' && node.arguments[2].type == 'FunctionExpression') {
            var dependencies = node.arguments[1]
              , factory = node.arguments[2];
            
            var ids = dependencies.elements.map(function(el) { return el.value });
            var vars = factory.params.map(function(el) { return el.name });

            // Backfill in the event that there are not enough defined
            // callback args (named dependencies) to match dependency
            // paths:
            //   define(['a/hey', 'a/what'], function(hey) {});
            while (vars.length < ids.length) {
              vars.push('__unnameddep__');
            }

            var reqs = createRequires(ids, vars);
            if (reqs) {
              tast = createProgram([reqs].concat(factory.body.body));
            } else {
              tast = createProgram(factory.body.body);
            }
            this.break();
          }
        } else if (isReturn(node)) {
          var parents = this.parents();
          
          if (parents.length == 5 && isDefine(parents[2]) && isAMD) {
            return createModuleExport(node.argument);
          }
        }
      }
    });
    
    if (!isAMD) {
      stream.queue(data);
      stream.queue(null);
      return;
    }
    
    tast = tast || ast;
    
    //console.log('-- TRANSFORMED AST --');
    //console.log(util.inspect(tast, false, null));
    //console.log('---------------------');
    
    var out = escodegen.generate(tast);
    stream.queue(out);
    stream.queue(null);
  }
};


function isDefine(node) {
  var callee = node.callee;
  return callee
    && node.type == 'CallExpression'
    && callee.type == 'Identifier'
    && callee.name == 'define'
  ;
}

function isReturn(node) {
  return node.type == 'ReturnStatement';
}

function createProgram(body) {
  return { type: 'Program',
    body: body };
}

function createRequires(ids, vars) {
  var decls = [];
  
  for (var i = 0, len = ids.length; i < len; ++i) {
    if (['require', 'module', 'exports'].indexOf(ids[i]) != -1) { continue; }
    
    decls.push({ type: 'VariableDeclarator',
      id: { type: 'Identifier', name: vars[i] },
      init: 
        { type: 'CallExpression',
          callee: { type: 'Identifier', name: 'require' },
          arguments: [ { type: 'Literal', value: ids[i] } ] } });
  }
  
  if (decls.length == 0) { return null; }
  
  return { type: 'VariableDeclaration',
    declarations: decls,
    kind: 'var' };
}

function createRequireExpression(id) {
  return {
    "type": "ExpressionStatement",
    "expression": {
      "type": "CallExpression",
      "callee": {
        "type": "Identifier",
        "name": "require"
      },
      "arguments": [
        {
          "type": "Literal",
          "value": id
        }
      ]
    }
  }
}

function createModuleExport(obj) {
  return { type: 'ExpressionStatement',
    expression: 
     { type: 'AssignmentExpression',
       operator: '=',
       left: 
        { type: 'MemberExpression',
          computed: false,
          object: { type: 'Identifier', name: 'module' },
          property: { type: 'Identifier', name: 'exports' } },
       right: obj } };
}