coffee-cache.js

var fs     = require('fs');
var path   = require('path');
var mkpath = require('mkpath');
// We don't want to include our own version of CoffeeScript since we don't know
// what version the parent relies on
var coffee;
try {
  coffee = require('coffee-script');
  // CoffeeScript 1.7 support
  if (typeof coffee.register === 'function') {
    coffee.register();
  }
} catch (e) {
  // No coffee-script installed in the project; warn them and stop
  process.stderr.write("coffee-cache: No coffee-script package found.\n");
  return;
}

// Directory to store compiled source
var cacheDir = process.env['COFFEE_CACHE_DIR'] || '.coffee';

// Root directory of project - use __dirname by default
var rootDir = process.env['COFFEE_ROOT_DIR'] || '.';

// Storing coffee's require extension for backup use
var coffeeExtension = require.extensions['.coffee'];

// Only log once if we can't write the cache directory
var logCouldNotWriteCache = function() {
  process.stderr.write(
    "coffee-cache: Could not write cache at " + cacheDir + ".\n"
  );
  logCouldNotWriteCache = function(){};
}

// Compile a file as you would with require and return the contents
function cacheFile(filename) {
  // First, convert the filename to something more digestible and use our cache
  // folder
  var cachePath = path.join(cacheDir, path.relative(rootDir, filename)).replace(/\.coffee$/, '.js');
  var content;

  // Try and stat the files for their last modified time
  try {
    var cacheTime = fs.statSync(cachePath).mtime;
    var sourceTime = fs.statSync(filename).mtime;
    if (cacheTime > sourceTime) {
      // We can return the cached version
      content = fs.readFileSync(cachePath, 'utf8');
    }
  } catch (err) {
    // If the cached file was not created yet, this will fail, and that is okay
  }

  // If we don't have the content, we need to compile ourselves
  if (!content) {
    // Read from disk and then compile
    var mapPath = path.resolve(cachePath.replace(/\.js$/, '.map'));
    var compiled = coffee.compile(fs.readFileSync(filename, 'utf8'), {
      filename: filename,
      sourceMap: true
    });
    content = compiled.js;

    // Since we don't know which version of CoffeeScript we have, make sure
    // we handle the older versions that return just the compiled version.
    if (content == null)
      content = compiled;

    try {
      // Try writing to cache
      mkpath.sync(path.dirname(cachePath));
      fs.writeFileSync(cachePath, content, 'utf8');
      if (mapPath)
        fs.writeFileSync(mapPath, compiled.v3SourceMap, 'utf8');
    } catch (err) {
      logCouldNotWriteCache()
    }
  }

  return content;
}

// Set up an extension map for .coffee files -- we are completely overriding
// CoffeeScript's since it only returns the compiled module.
require.extensions['.coffee'] = function(module, filename) {
  var content = cacheFile(filename);
  if (content)
    // Successfully retrieved the file from disk or the cache
    return module._compile(content, filename);
  else
    // Something went wrong, so we can use coffee's require
    return coffeeExtension.apply(this, arguments);
};

// Export settings
module.exports = {
  setCacheDir: function(dir, root){
    if(root) {
      rootDir = root;
    }

    cacheDir = dir;
    return this;
  },
  cacheFile: cacheFile,
};