simple-preprocessor

A simple Javascript preprocessor. I intended it for node.js, but it can be used for any javascript framework.

Installation

npm install -g simple-preprocessor

Usage

Surround parts of your code you want to conditionally compile in the following way:

//ifdef TEST 
function TestFunction() 
{ 
    //some code 
}
//else
function TestFunction2()
{
   //some code
}
//endif

Without Config File

Now, in order to compile this code you will need to run simple-preprocessor in your source directory and specify the TEST directive:

simple-preprocessor -D TEST

In this case, the result of the preprocessing will be a file with the same name with the TEST block included, but with the else block commented out:

//ifdef TEST 
function TestFunction() 
{ 
    //some code 
}
//else
//function TestFunction2()
//{
//   //some code
//}
//endif

If you don't want to compile this block of code, then don't include this directive:

simple-preprocessor

In this case, the result of the preprocessing will be a file with the same name (don't worry, your original files are cached within the .simp-prep-cache directory before the preprocessing) but with the TEST block commented out, and the else block uncommented:

//ifdef TEST 
//function TestFunction() 
//{ 
//    //some code 
//}
//else
function TestFunction2()
{
   //some code
}
//endif

Of course, you can omit the else block altogether, and this syntax is perfectly valid:

//ifdef TEST 
function TestFunction() 
{ 
    //some code 
}
//endif

Above examples expect you to run simple-preprocessor from the root directory of your project. Simple-preprocessor automatically walks through all .js files in the root directory and in all subdirectories. Should you wish to set the directory (or directories) to walk manually, you would do this:

simple-preprocessor -dir path/to/my/dir path/to/another/dir

To exclude some directories from the preprocessing you do this (the node_modules directory is excluded by default):

simple-preprocessor -exclude_dirs dirname anotherDirName

Directories with these names will be excluded from the preprocessing, irrespective of their relative path (i.e. ./dir/dirname, ./dirname, dir/dir2/anotherDirName etc. will all be excluded.

With Config File

It's easier however to create a config file named simp-prep-config.json in the root directory of your project. You can use command simple-preprocessor init to automatically create a sample config file in the current directory. simp-prep-config.json is a JSON formatted file which supports all above directives. Here is an example:

{
   "D" :
   {
      "TEST" : false,
      "RELEASE" : true
   },
   "dir" : [ "testDir", "myDir" ],
   "exclude_dirs" : [ "anotherDir" ]
}

Here "dir" specifies the directories to be preprocessed. Other directories in your proejct will be left as they are. Leave this empty ([]) if you want to preprocess all directories. "D" specifies defined (and undefined, if they are false) directives. exclude_dirs specifies directories key names to exclude. Then you just run simple-preprocessor in the directory with the simp-prep-config.json file.

Updates

• You can now specify several directories as input to the -dir command. This also relates to the dir property of the config file. In case of config file, you can now specify an array of strings (representing relative directory paths), instead of a single string. See examples above, they all now use this new feature.
• All your files are now backed up before the preprocessing into the .simp-prep-cache directory which is created in the directory where simple-preprocessor is called. If something happens during the preprocessing (like sudden power outage while a file is being written to), you can use this cache to restore files.
• .simp-prep-cache and .git directories are now excluded by default.

Old syntax

Old syntax with //SIMP_PREP DIRECTIVE and //SIMP_PREP_END DIRECTIVE is still supported, but deprecated. Please, use new syntax.

Nested directives

Nested directives like those shown below are not supported yet:

//ifdef TEST 
function TestFunction() 
{
//ifdef TEST_2
    //some code
//endif    
}
//endif

The behavior is undefined is this case.

Test

To test run

npm test

from the directory where simple-preprocessor is installed.