How Can I Simulate Do-While Loops and Handle Iterators in Python?

Emulating Do-While Loops in Python

In Python, a do-while loop is not natively supported. However, there are several methods to achieve a similar functionality.

One approach is to use a while True loop, as demonstrated below:

while True:
  # Execute loop body
  if break_condition:
    break

Alternatively, you can use a while loop followed by an if statement to execute the loop body before checking the break condition:

# Execute loop body
if not break_condition:
  continue

Handling the StopIteration Exception

To correctly handle the StopIteration exception raised when iterating over a list or iterable, use a try-except block:

iterator = list_of_ints.__iter__()
element = None

while True:
  try:
    element = iterator.next()
  except StopIteration:
    break

  print(element)

Emulating a State Machine

In the provided example, a state machine was implemented using a do-while loop. To emulate this in Python, you can use loops with conditional break statements:

while True:
  if state == STATE_CODE:
    if "//" in s:
      tokens.add(TOKEN_COMMENT, s.split( "//" )[1])
      state = STATE_COMMENT
    else:
      tokens.add(TOKEN_CODE, s)

  if state == STATE_COMMENT:
    if "//" in s:
      tokens.append(TOKEN_COMMENT, s.split( "//" )[1])
      state = STATE_CODE
    else:
      # Re-evaluate same line
      continue

  try:
    s = i.next()
  except StopIteration:
    break

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