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unmodulizer.js
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395 lines (348 loc) · 11.2 KB
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/*
* Copyright 2013 Lloyd Smith II
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
var escodegen = require('escodegen'),
esprima = require('esprima'),
path = require('path');
var variableNamers = {
'default': defaultVariableNamer,
globals: globalsVariableNamer,
namespace: namespaceVariableNamer
};
module.exports = {
unmodulize: unmodulize,
variableNamers: variableNamers,
makeModuleStub: makeModuleStub
};
function unmodulize(code, variableNamer, stubs) {
var syntax = esprima.parse(code, {
loc: true,
range: true,
raw: true,
tokens: true,
comment: true,
tolerant: false
});
// insert all the stubs first in the program body:
Array.prototype.unshift.apply(syntax.body, (stubs || []).map(function(stub) { return stub.syntax; }));
var outputAst = {
type: 'Program',
body: []
},
moduleIdToVarNameMap = {},
varNameToModuleIdMap = {},
count = 0;
syntax.body.forEach(function(node) {
var parsedNode, replacement;
if((parsedNode = parseDefineCall(node))) {
replacement = getTransformedDefineCall();
} else if((parsedNode = parseRequireCall(node))) {
replacement = getTransformedRequireCall();
} else if((parsedNode = parseRequireCallWithNoCallback(node))) {
// make sure all dependencies are known!
parsedNode.deps.forEach(function(moduleId) {
if(!isModuleDefined(moduleId)) {
throw new Error('module "' + moduleId +
'" in require invocation without callback is not defined! '
+ debugJSON(node.loc));
}
});
replacement = {
type: 'EmptyStatement' // TODO: omit this entirely
};
}
outputAst.body.push(replacement || node);
function getTransformedDefineCall() {
var varName = registerNewVarNameForModule(parsedNode.moduleId);
// replace:
//
// define(moduleId, [dep1, dep2, ...], function(one, two, ...) { })
//
// with:
//
// var moduleId = (function(one, two, ...){})(dep1, dep2, ...);
return {
type: 'VariableDeclaration',
declarations: [
{
type: 'VariableDeclarator',
id: {
type: 'Identifier',
name: varName
},
init: {
type: 'CallExpression',
callee: parsedNode.factory,
'arguments': parsedNode.deps.map(function(depId) {
var depVarName = moduleIdToVarNameMap[depId];
if(!depVarName) {
throw new Error('No previous define for dependency "' +
depId + '" used in factory for module "' +
parsedNode.moduleId + '": location: ' +
debugJSON(node.loc));
}
return {
type: 'Identifier',
name: moduleIdToVarNameMap[depId]
};
})
}
}
],
kind: 'var'
};
}
function getTransformedRequireCall() {
var requireArgs = parsedNode.deps.map(function(depId) {
if(!moduleIdToVarNameMap[depId]) {
throw new Error('require has unknown dependency "' + depId +
'" : ' + debugJSON(node.loc) + '\nIdentifier map: ' + debugJSON(moduleIdToVarNameMap));
}
return {
type: 'Identifier',
name: moduleIdToVarNameMap[depId]
};
});
// replace:
//
// require([dep1, dep1, ...], function(one, two, ...) {} )
//
// with:
//
// (function(one, two, ...){})(dep1, dep2, ...);
return {
type: 'ExpressionStatement',
expression: {
type: 'CallExpression',
callee: parsedNode.callback,
'arguments': requireArgs
}
};
}
});
return escodegen.generate(outputAst);
function isModuleDefined(moduleId) {
// TODO: what if sb uses 'toString' for a module id?
return moduleIdToVarNameMap.hasOwnProperty(moduleId);
}
function isVarNameTaken(varName) {
return varNameToModuleIdMap.hasOwnProperty(varName);
}
function registerNewVarNameForModule(moduleId) {
var varName;
if(isModuleDefined(moduleId)) {
throw new Error('module already defined: ' +
moduleId + ' ' + debugJSON(node.loc));
}
// TODO: check that varName is a valid identifier, etc.
varName = variableNamer(moduleId, count);
if(isVarNameTaken(varName)) {
throw new Error('variableNamer function produced a non-unique variable name for module: [' +
moduleId + '] , count: ' + count + ' : given varName: ' +
varName + 'varNameToModuleIdMap => ' +
debugJSON(varNameToModuleIdMap));
}
count++;
moduleIdToVarNameMap[moduleId] = varName;
varNameToModuleIdMap[varName] = moduleId;
return varName;
}
}
// variable namer intended for situations where you are wrapping in a closure
// and minifying the code so that the variable names will be changed anyway.
function defaultVariableNamer(moduleId, count) {
return '____$unmodulizer$'+count+'$'+sanitizeVarName(moduleId);
}
function sanitizeVarName(varName) {
varName = varName.replace(/[^a-zA-Z0-9_\$]/g,'')
.replace(/^([^a-zA-Z])/,function(match, ch) {
return '$'+ch.replace(/[^a-zA-Z0-9\$_]/,'');
});
if(varName === '') {
varName = '$';
}
return varName;
}
// turn a module name like: foo/bar/car => FooBarCar
function globalsVariableNamer(moduleId) {
var name = moduleId.replace(/\/([a-z])/g, function(match, ch) {
return ch.toUpperCase();
})
.replace(/^([a-z])/, function(match, ch) {
return ch.toUpperCase();
})
.replace(/[^a-zA-Z0-9_\$]/g, '');
return name;
}
function namespaceVariableNamer(moduleId) {
// TODO - do AST transform to create namespace as we go (if not there)
return moduleId.replace(/\//g, '.');
}
function parseDefineCall(node) {
var result;
if(isFuncCall(node, 'define')) {
var expr = node.expression;
var args = expr['arguments'];
if(args.length === 3 &&
args[0].type === 'Literal' &&
args[1].type === 'ArrayExpression' &&
args[2].type === 'FunctionExpression') {
var moduleId = args[0].value;
result = {
moduleId: moduleId,
deps: parseDepsArg(args[1], function(depId) {
if(depId[0] === '.') {
return path.resolve('/'+moduleId.substring(0, moduleId.lastIndexOf('/')), depId).substring(1);
// TODO: hack to handle relative paths
} else {
return depId;
}
}),
factory: args[2]
};
}
}
return result;
}
function parseRequireCall(node) {
var result;
if(isFuncCall(node, 'require')) {
var expr = node.expression,
args = expr['arguments'];
if(args.length === 2 &&
args[0].type === 'ArrayExpression' &&
args[1].type === 'FunctionExpression') {
result = {
deps: parseDepsArg(args[0]),
callback: args[1]
};
}
}
return result;
}
/**
* Gets an array of module ids from the ArrayExpression of a 'define'
* or 'require' call. The factory can be used to further
* process the module id (e.g., resolve relative module paths).
*
* @param arg {ArrayExpression}
* @param factory? {function}
* @return {Array} of {string} dependency ids
*/
function parseDepsArg(arg, factory) {
return arg.elements.map(function(depEl) {
// TODO: assert a {string} literal
if(typeof factory === "function") {
return factory(depEl.value, depEl);
}
return depEl.value;
});
}
// parse a require invocation that does not have a callback:
//
// require(['dep1', 'dep2', ...]);
//
// the purpose of such a require call can only be for the side effects,
// of the modules having loaded; in practice, these side effects are only
// useful for "main" modules (the main entry-point to an application);
//
// most modules simply return constructors, functions, or namespaces and
// do minimal work upon initialization (never do work in constructors, right).
//
// so ... when we encounter these, we need to delete them! why?
// the corresponding defines for the dependencies will already have been erased
// and therefore had its factory invoked.
//
// Put another, a missing callback is the same as a no-op callback:
//
// require(['dep1'], function() {
// });
//
// =>
// (function() {})(dep1); // <---- pointless
function parseRequireCallWithNoCallback(node) {
var expr, result;
if(isFuncCall(node, 'require')) {
var expr = node.expression,
args = expr['arguments'];
if(args.length === 1 &&
args[0].type === 'ArrayExpression') {
result = {
deps : parseDepsArg(args[0]),
skip: true
};
}
}
return result;
}
function isFuncCall(node, name) {
var expr;
if(node.type === "ExpressionStatement" && (expr = node.expression) &&
expr.type === "CallExpression" &&
expr.callee.type === "Identifier" &&
expr.callee.name === name) {
return true;
}
return false;
}
function makeModuleStub(moduleId, deps, expressionSource) {
// TODO: allow dependencies
var expr = esprima.parse(expressionSource);
if(!(expr.body.length === 1 && expr.body[0].type === 'ExpressionStatement')) {
throw new Error('ExpressionStatement required for stubbed module "' +
moduleId + '" : source => "' + expressionSource + '" parsed to ' + debugJSON(expr));
}
return {
"type": "ExpressionStatement",
"expression": {
"type": "CallExpression",
"callee": {
"type": "Identifier",
"name": "define"
},
"arguments": [
{
"type": "Literal",
"value": moduleId
},
{
"type": "ArrayExpression",
"elements": []
},
{
"type": "FunctionExpression",
"id": null,
"params": [],
"defaults": [],
"body": {
"type": "BlockStatement",
"body": [
{
"type": "ReturnStatement",
"argument": expr.body[0].expression
}
]
},
"rest": null,
"generator": false,
"expression": false
}
]
}
};
}
function debugJSON(obj) {
return JSON.stringify(obj, null, 2);
}