PyQt5实现QLineEdit正则表达式输入验证器

from PyQt5 import QtWidgets, QtCore, QtGui, Qt
import re

############## QLineEdit正则表达式输入验证器
class LineEditRegExpValidator(QtGui.QValidator):

  '''
  # 默认为科学计数法输入验证器

  用法
  SciNotValidator = LineEditRegExpValidator() # 创建一个QLineEdit正则表达式输入验证器的类，默认为科学计数法输入验证器

  self.LineEdit1.setValidator(SciNotValidator) # 设置验证器（启用）
  self.LineEdit1.installEventFilter(SciNotValidator) # QLineEdit清空内容且游标失焦时，自动填充上一次的字符串内容

  self.LineEdit2.setValidator(SciNotValidator)
  self.LineEdit2.installEventFilter(SciNotValidator)

  self.LineEdit3.setValidator(SciNotValidator)
  self.LineEdit3.installEventFilter(SciNotValidator)

  Validator.validate() is abstract and must be overriddenValidator.validate() is abstract and must be overridden
  '''

  def __init__(
    self, 

    # 编辑状态框输入结束允许的字符串
    fullPatterns=[
      r"[+|-]?[0-9]+\.?[0-9]*(?:[Ee][+|-]?[0-9]+)?", 
      r'[+|-]{0,1}nan', r'[+|-]{0,1}inf'
      ], 
    
    # 编辑状态框输入尚未结束允许的字符串
    partialPatterns=[
      r'[+|-]?[0-9]+\.?[0-9]*(?:[Ee][+|-]?)?', 
      r'-', 
      r'\+', 
      r'[+|-]{0,1}nan', 
      r'[+|-]{0,1}na', 
      r'[+|-]{0,1}n', 
      r'[+|-]{0,1}inf', 
      r'[+|-]{0,1}in', 
      r'[+|-]{0,1}i'
      ],
    
    fixupString='1.0'
    ):

    super(LineEditRegExpValidator, self).__init__()
    self.fullPatterns = fullPatterns
    self.partialPatterns = partialPatterns
    self.fixupString = fixupString
  

  # 实时监听文本框的改变
  # 可能是键盘单个字符'n'输入, 也有可能是粘贴多个字符'nan'输入
  def validate(self, string, pos) -> QtGui.QValidator.State: # string为编辑状态框中可见的字符串+输入字符/字符串

    # 编辑过程结束，若返回True，将编辑状态框中的字符串填入LineEdit,若返回Flase则自动调用self.fixup方法，将fixup方法返回的字符串填入LineEdit
    if self.acceptable_check(string):
      #print(f'QtGui.QValidator.Acceptable:{QtGui.QValidator.Acceptable}')
      return QtGui.QValidator.Acceptable, string, pos # QtGui.QValidator.Acceptable = 2; 
    

    # 编辑过程中允许出现的字符串
    if self.intermediate_check(string):
      #print(f'QtGui.QValidator.Intermediate:{QtGui.QValidator.Intermediate}')
      return QtGui.QValidator.Intermediate, string, pos # QtGui.QValidator.State = 1;
    # 编辑过程中不允许出现的字符串(本次输入的单个字符或字符串无效)
    else:
      #print(f'QtGui.QValidator.Invalid:{QtGui.QValidator.Invalid}')
      return QtGui.QValidator.Invalid, string, pos


  # 编辑状态框验证通过, 编辑状态框单个字输入符成功
  def acceptable_check(self, string) -> bool:
    True_ = 0
    for fullPattern in self.fullPatterns:
      if re.fullmatch(fullPattern, string):
        True_ += 1
      else:
        continue
    if True_ != 0:
      return True
    else:
      return False

  # 输入还未结束允许的字符串
  def intermediate_check(self, string): #-> bool;  string为编辑状态框中可见的字符串
    """
    Checks if string makes a valid partial float, keeping in mind locale dependent decimal separators.
    """
    if string == '':
      return True
    for partialPattern in self.partialPatterns:
      if re.fullmatch(partialPattern, string):
        return True
      else:
        pass

  # 
  def eventFilter(self, lineEdit, event): # -> bool
    # FocusIn event
    # 每当fous in时，更新LineEditRegExpValidator的fixupString
    # 输入验证器
    '''
    SciNotValidator = LineEditRegExpValidator()

    self.LineEdit1.setValidator(SciNotValidator)
    self.LineEdit1.installEventFilter(SciNotValidator)
    '''

    if event.type() == QtCore.QEvent.FocusIn:
      # do custom stuff
      # print('focus in')

      # self.lineEdit_zhuansu.installEventFilter(SciNotValidator)， 在本类中，widget是self.lineEdit，执行函数self.lineEdit.text(), 其它类不一定有text()方法

      #lineEdit.selectAll()
      QtCore.QTimer.singleShot(0, lineEdit.selectAll) # 0ms
      self.fixupString = lineEdit.text()

      #print(self.fixupString)
      # return False so that the lineEdit will also handle the event
      # otherwise it won't focus out
      return False
    else:
      # we don't care about other events
      return False

  # 重写QValidator的fixup(str)方法。可以在切换焦点后，直接修改不合规则的字符串。参数str是经过validate()方法验证后的字符串；
  def fixup(self, string) -> str:
    """
    Fixes up input text to create a valid float. Puts an empty string on failure.
    """
    print(string)

    True_ = 0
    for fullPattern in self.fullPatterns:
      if re.fullmatch(fullPattern, string):
        True_ += 1
      else:
        continue
    if True_ != 0:
      return string
    else:
      return self.fixupString


# listWidget、tableWidget输入数据检查
class LineEditDelegate_Regx(QtWidgets.QStyledItemDelegate):
 # 科学计数法正则表达式
  regx = r"-?\ *[0-9]+\.?[0-9]*(?:[Ee]\ *-?\ *[0-9]+)?" #
  """
  -?    optionally matches a negative sign (zero or one negative signs)
  \ *    matches any number of spaces (to allow for fORMatting variations like - 2.3 or -2.3)
  [0-9]+  matches one or more digits
  \.?    optionally matches a period (zero or one periods)
  [0-9]*  matches any number of digits, including zero
  (?: ... ) groups an expression, but without forming a "capturing group" (look it up)
  [Ee]   matches either "e" or "E"
  \ *    matches any number of spaces (to allow for formats like 2.3E5 or 2.3E 5)
  -?    optionally matches a negative sign
  \ *    matches any number of spaces
  [0-9]+  matches one or more digits
  ?     makes the entire non-capturing group optional (to allow for the presence or absence of the exponent - 3000 or 3E3

  https://stackoverflow.com/questions/18152597/extract-scientific-number-from-string
  """

  """
  用法：
  def __init__(self, parent=None):
    super(NewClassName, self).__init__(parent)
    self.setupUi(self)

    delegate = LineEditDelegate_Regx(regx=None)
    self.listWidget_ShuZhiLieBiao.setItemDelegate(delegate)
    self.tableWidget.setItemDelegate(delegate)
  """
  def __init__(self, regx=None, parent=None):
    super(LineEditDelegate_Regx, self).__init__(parent)
    if regx == None:
      pass
    else:
      self.regx = regx

  # 方法重写
  def createEditor(self, parent, option, index): # self, parent, option, index四个参数均不能少
    editor_qlineedit = QtWidgets.QLineEdit(parent)
    #SciNotValidator = QtGui.QRegExpValidator(QtCore.QRegExp(self.regx))
    SciNotValidator = LineEditRegExpValidator()
    editor_qlineedit.setValidator(SciNotValidator)
    return editor_qlineedit # LineEditDelegate_Regx(regx=None, parent=None), QStyledItemDelegate(parent: QObject = None)

"""
# LineEdit输入数据检查
def LineEditInputChecking(lineEdit, regx=None):
  '''
  用法：
  LineEditInputChecking(lineEdit=self.lineEdit_zhuansu)
  '''
  if regx == None:
    regx = r"-?\ *[0-9]+\.?[0-9]*(?:[Ee]\ *-?\ *[0-9]+)?"
  reg_ex = QtCore.QRegExp(regx)
  input_validator = QtGui.QRegExpValidator(reg_ex, lineEdit)
  lineEdit.setValidator(input_validator)
"""