index.js

var es = require('event-stream');
var swig = require('swig-templates');
var clone = require('clone');
var gutil = require('gulp-util');
var ext = gutil.replaceExtension;
var PluginError = gutil.PluginError;
var fs = require('fs');
var path = require('path');

function extend(target) {
  'use strict';
  var sources = [].slice.call(arguments, 1);
  sources.forEach(function(source) {
    for (var prop in source) {
      if (source.hasOwnProperty(prop)) {
        target[prop] = source[prop];
      }
    }
  });
  return target;
}

module.exports = function(options) {
  'use strict';

  var opts = options ? clone(options) : {};
  opts.ext = opts.ext || ".html";

  if (opts.defaults) {
    swig.setDefaults(opts.defaults);
  }

  if (opts.setup && typeof opts.setup === 'function') {
    opts.setup(swig);
  }

  function gulpswig(file, callback) {

    var data = opts.data || {}, jsonPath;

    if (typeof data === 'function') {
      data = data(file);
    }

    if (file.data) {
      data = extend(file.data, data);
    }

    if (opts.load_json === true) {
      if (opts.json_path) {
        jsonPath = path.join(opts.json_path, ext(path.basename(file.path), '.json'));
      } else {
        jsonPath = ext(file.path, '.json');
      }

      // skip error if json file doesn't exist
      try {
        data = extend(JSON.parse(fs.readFileSync(jsonPath)), data);
      } catch (err) {}
    }

    try {

      var _swig = opts.varControls ? new swig.Swig(opts) : swig;
      var tpl = _swig.compile(String(file.contents), {filename: file.path});
      var compiled = tpl(data);

      file.path = ext(file.path, opts.ext);
      file.contents = new Buffer(compiled);

      callback(null, file);
    } catch (err) {
      callback(new PluginError('gulp-swig', err));
      callback();
    }
  }

  return es.map(gulpswig);
};