對Regex練習器的改進

正則 對Regex練習器的改進，原貼ID901680

覆蓋原execIt函數
修改後的execIt函數允許對多個Regex進行匹配(每個Regex一行)，並對每一個匹配成分顯示出是第幾個Regex匹配的。
這可視為文法分析的雛形，只要對匹配產生相應的動作。

function execIt(form) {
  var mode
  if(form.chkmode.checked) mode = "gi"
  else mode = "g"
  var regexpArray = form.regexp.value.split("\r\n")  //擷取Regex到數組

  if(nextpoint == 0) form.reglist.value = ""
  var key = true
  if(form.scankmode.checked) key = false
  else nextpoint = 0
  do {
    var offs = 9999999999
    var pos = -1
    var input = form.main.value.substr(nextpoint)
    //對每個Regex進行匹配
    for(var i=0;i<regexpArray.length;i++) {
      re.compile(regexpArray[i],mode)
      var matchArray = re.exec(input)
      if(matchArray) {
        if(offs > matchArray.index) {
          offs = matchArray.index
          pos = i  //儲存距離起始位子最近的匹配
        }
      }
    }
    if(pos>=0) {
      re.compile(regexpArray[pos],mode)
      var matchArray = re.exec(input)
      for(var i=1;i<matchArray.length;i++)
        matchArray[i] = "$"+i+":"+matchArray[i]
      form.reglist.value = "["+(pos+1)+"]"+(nextpoint+matchArray.index)+" => " + matchArray[0] +"\n"+form.reglist.value
      form.matchlist.value = "$0:"+matchArray.join("\n")
      nextpoint = nextpoint + matchArray.index + matchArray[0].length
    }else {
      if(!key)
        form.reglist.value = "沒有找到\n" + form.reglist.value
      form.matchlist.value = " "
      nextpoint = 0
      key = false
    }
  }while(key)
}