C Preprocessor

C Preprocessor is a preprocessor created with Node.js only and running like a C preprocessor with # directives.
It was originally designed for Javascript but you can use it with any language you want.
See changelog here.

Installation

For local installation, run the following command:

npm install c-preprocessor --save

For global installation, run the following command:

npm install -g c-preprocessor

Compile a file/text

In command line

If you have installed this package in global, you can run c-preprocessor and pass your main file and output file in arguments.

c-preprocessor mainFile.js outputFile.js

Additionally you can specify a configuration file (see below for it's format):

c-preprocessor --config configFile.js mainFile.js outputFile.js

With require()

var compiler = require("c-preprocessor");
 
 
// To compile a file
compiler.compileFile(fileName, [ options, ] function(err, result) {
 
    if (err)
        return console.log(err);
 
    console.log(result);
});
 
 
// To compile a text
compiler.compile(code, [ options, ] function(err, result) {
    // ...
});
 
 
// Or use Compiler class
var c = new compiler.Compiler([options]);
c.on('success', /* ... */)
c.on('error', /* ... */)
 
c.compile(code);
// or
c.compileFile(fileName);

Customize options

This are the defaults options. You can modify them by passing an option object.

var options = {
    
    // Predefined constants (ex: { "MY_CONST": "42" })
    constants: {},
 
    // Predefined macros (ex: { "MACRO": "(a,b) a+b" })
    macros: {},
 
    // End of line character
    newLine: '\n',
 
    // Escape '//#' & '/*#' comments (see extra/comments)
    commentEscape: true,
    
    // Empty lines to add between code and included files
    includeSpaces: 0,
    
    // Limit of empty following lines (0 = no limit)
    emptyLinesLimit: 0,
 
    // Base path for including files
    basePath: './',
 
    // Stop the compiler when an error ocurred ?
    stopOnError: true,
 
    // Must constants in #enum directive be in hexadecimal ?
    enumInHex: true
};

Usage

Like a C preprocessor

Include

#include "file.js"

Include and parse a file.

Define

// Define a constant 
#define MY_CONST 42
 
// Define a macro 
#define SUM(a,b) a + b

Create a constant or a macro.

Undefine

#undef MY_CONST

Delete a constant or a macro.

Condition

#if A + B == 5 && defined(MY_CONST)
  // Do stuff 
#elif "MY_CONST2" == "House"
  // Do other stuff 
#else
  // Do other stuff 
#endif
 
#ifndef MY_CONST3
  // Do stuff 
#endif

C like conditions.
#if condition is evaluated in JS so you must add " between string constants.
Note: #ifdef C and #ifndef C are faster than #if defined(C) and #if !defined(C).

Pragma once

#pragma once

Include the current file once.

Error

#error This is an error

Stop the compiler and log the message given after the directive.

Extra

Compiler constants

__TIME__ // Current time 
__DATE__ // Current date 
__LINE__ // Current line (where this constant is used). 
__FILE__ // Current file (where this constant is used). 

This constants are predefined by the compiler.

Comments

//# One line comment 
 
/*#
 
Multi-lines comment
 
#*/

This comments will be deleted in the compiled file.
Note: options.commentEscape must be true.

Enumeration

// Here A=0, ..., D=3 
#enum
  A, B, C, D
#endenum
 
// With options, so Car=5, .., Truck=25 
#enum start=5, step=10
  Car, Bike, Truck
#endenum

C like enumeration.
You can use this directive for creating a lot of constants.