Groovyでdo-whileループ。http://d.hatena.ne.jp/fumokmm/20110630/1309446463

groovy_doloop.groovy

//break条件を受け取る感じで
class BreakException extends Exception {}
Object.metaClass.doBreak = { cond ->
  if (cond()){
    println 'break!'
    throw new BreakException()
  }
}
Object.metaClass.doloop = { proc ->
  [  // whileの実装
    'while': { cond ->
      try {
        proc()
        while(cond()) {
          proc()
        }
      } catch(BreakException ignore) {
      }
    },
    // untilの実装
    'until': { cond ->
      try {
        proc()
        while(!cond()) {
          proc()
        }
      } catch(BreakException ignore) {
      }
    }
  ]
}

// 以下、デモ
def a = 1
doloop {
  println "[in do-while loop] $a"
  a++
  doBreak {a == 5}
}.while{ a < 10 }

doloop {
  println "[in do-until loop] $a"
  a++
  doBreak {a == 10}
}.until{ a == 20 }

groovyDoWhile_error.groovy

// こちらは以前試していた失敗作
class DoWhile {
  def proc
  def _do(Closure proc) {
    this.proc = proc
    return this
  }
  def _while(Closure cond) {
    10.times {
      println cond()
      this.proc()
    }
  }
}

def dw = new DoWhile()
int i = 0
dw._do {
  println "hello ${++i}"
}._while {
  i < 50
}

// => java.lang.VerifyError: (class: ConsoleScript46$_run_closure2, method: doCall signature: (Ljava/lang/Object;)Ljava/lang/Object;) Expecting to find integer on stack
//    at ConsoleScript46.run(ConsoleScript46:17)
//    at groovy.lang.GroovyShell.runScriptOrMainOrTestOrRunnable(GroovyShell.java:266)
//    at groovy.lang.GroovyShell.run(GroovyShell.java:517)
//    at groovy.lang.GroovyShell.run(GroovyShell.java:172)
//    at groovy.lang.GroovyShell$run.call(Unknown Source)
//    at groovy.ui.Console$_runScriptImpl_closure16.doCall(Console.groovy:910)