concat.js

/*
 * grunt-contrib-concat
 * http://gruntjs.com/
 *
 * Copyright (c) 2016 "Cowboy" Ben Alman, contributors
 * Licensed under the MIT license.
 */

'use strict';

module.exports = function(grunt) {

  // Internal lib.
  var comment = require('./lib/comment').init(grunt);
  var chalk = require('chalk');
  var sourcemap = require('./lib/sourcemap').init(grunt);

  grunt.registerMultiTask('concat', 'Concatenate files.', function() {
    // Merge task-specific and/or target-specific options with these defaults.
    var options = this.options({
      separator: grunt.util.linefeed,
      banner: '',
      footer: '',
      stripBanners: false,
      process: false,
      sourceMap: false,
      sourceMapName: undefined,
      sourceMapStyle: 'embed'
    });

    // Normalize boolean options that accept options objects.
    if (options.stripBanners === true) {
      options.stripBanners = {};
    }
    if (options.process === true) {
      options.process = {};
    }

    // Process banner and footer.
    var banner = grunt.template.process(options.banner);
    var footer = grunt.template.process(options.footer);

    // Set a local variable for whether to build source maps or not.
    var sourceMap = options.sourceMap;

    // If content is not embedded and it will be modified, either exit or do
    // not make the source map.
    if (
      sourceMap && options.sourceMapStyle === 'link' &&
        (options.stripBanners || options.process)
    ) {
      // Warn and exit if --force isn't set.
      grunt.warn(
        'stripBanners or process option is enabled. ' +
        'Set sourceMapStyle option to \'embed\' or \'inline\'.'
      );
      // --force is set, continue on without the source map.
      grunt.log.warn('Skipping creation of source maps.');
      // Set sourceMap to false to keep maps from being constructed.
      sourceMap = false;
    }

    var exitEarly = {};
    try {
      // Iterate over all src-dest file pairs.
      this.files.forEach(function(f) {
        // Initialize source map objects.
        var sourceMapHelper;
        if (sourceMap) {
          sourceMapHelper = sourcemap.helper(f, options);
          sourceMapHelper.add(banner);
        }

        // Concat banner + specified files + footer.
        var src = banner + f.src.filter(function(filepath) {
          // Warn on invalid source files (if nonull was set). They will be
          // removed if --force is specified.
          if (!grunt.file.exists(filepath)) {
            grunt.fail.warn('Source file "' + filepath + '" not found.');
            if (!grunt.option('force')) {
              // See the catch clause below for why we do this.
              throw exitEarly;
            }
            return false;
          }
          return true;
        }).map(function(filepath, i) {
          if (grunt.file.isDir(filepath)) {
            return;
          }
          // Read file source.
          var src = grunt.file.read(filepath);
          // Process files as templates if requested.
          if (typeof options.process === 'function') {
            src = options.process(src, filepath);
          } else if (options.process) {
            src = grunt.template.process(src, options.process);
          }
          // Strip banners if requested.
          if (options.stripBanners) {
            src = comment.stripBanner(src, options.stripBanners);
          }
          // Add the lines of this file to our map.
          if (sourceMapHelper) {
            src = sourceMapHelper.addlines(src, filepath);
            if (i < f.src.length - 1) {
              sourceMapHelper.add(options.separator);
            }
          }
          return src;
        }).join(options.separator) + footer;

        if (sourceMapHelper) {
          sourceMapHelper.add(footer);
          sourceMapHelper.write();
          // Add sourceMappingURL to the end.
          src += sourceMapHelper.url();
        }

        // Write the destination file.
        grunt.file.write(f.dest, src);

        // Print a success message.
        grunt.verbose.write('File ' + chalk.cyan(f.dest) + ' created.');
      });
    } catch (reason) {
      if (reason === exitEarly) {
        // grunt.fail.warn uses the "exit" library, which doesn't stop the
        // process synchronously on Node.js 0.10 on Windows, which could result
        // in files still being concatenated even when some are missing. See:
        // https://github.com/nodejs/node-v0.x-archive/issues/3584#issuecomment-8034529
        // Therefore, we throw a unique reference to emulate exiting early.
        return;
      }
      throw reason;
    }
  });

};