gulp-forkat

Split the stream, merge the substreams back, cache the state

var forkat = require('gulp-forkat');
var filter = forkat();
var lesscss = forkat();

return gulp.src(['jquery.js', '**/*.ctpl'])
    .pipe(conkitty({
        common: 'common.js',
        templates: 'tpl.js',
        deps: true
    }))
    .pipe(filter('**/*.js', function(src) {
        return mode === 'prod' ?
            src
                .pipe(concat('app.js'))        
                .pipe(uglify({preserveComments: 'some'}))
            :
            src;
    }))
    .pipe(filter('**/*.{less,css}', function(src) {
        var ret = src
            .pipe(lesscss({each: true}, function() {
                return src
                    .pipe(less())
                    .pipe(prefix('last 1 version', '> 1%'));
            }))
            .pipe(lesscss.merge());
        return mode === 'prod' ?
            ret
                .pipe(concat('app.css'))
                .pipe(minifyCSS())
            :
            ret;
    }))
    .pipe(filter(['!**/*.js', '!**/*.css'], function(src) {
        return src;
    }))
    .pipe(filter.merge())
    .pipe(gulp.dest('build'));