gulp-first

A Gulp plugin for passing through only the first object (source file) selected.

Used combination with gulp-newer, this filter will emit only the first file object if any of the files from a gulp.src(...) glob are newer than the target. This can be useful with gulp-exec for many:1 build tasks where some external tool needs to be invoked if the target is out-of-date.

npm install -D gulp-first

use (in a gulpfile)

var gulp = require('gulp')
var newer = require('gulp-newer')
var first = require('gulp-first')
var exec = require('gulp-exec')

var paths = {
  src: ["pom.xml", "src/**/*", "resources/**/*", "test/**/*"],
  target: "target/antlr4-typescript-4.6-SNAPSHOT-complete.jar"
}

gulp.task('maven', function () {
  return gulp.src(paths.src, { read: false })
    .pipe(newer(paths.target))
    .pipe(first())
    .pipe(exec('mvn install -Dmaven.test.skip=true'))
    .pipe(exec.reporter())
})

This usage pattern will ensure that the mvn command is executed only once, to generate the .jar file, no matter how many source files have changed.