scanner.py

"""
Sample script to test ad-hoc scanning by table drive.
This accepts a number with optional decimal part [0-9]+(\.[0-9]+)?

NOTE: suitable for optional matches
"""

def getchar(text,pos):
	""" returns char category at position `pos` of `text`,
	or None if out of bounds """
	
	if pos<0 or pos>=len(text): return None
	
	c = text[pos]
	
	# **Σημείο #3**: Προαιρετικά, προσθέστε τις δικές σας ομαδοποιήσεις
	
	
	return c	# anything else
	


def scan(text,transitions,accepts):
	""" scans `text` while transitions exist in
	'transitions'. After that, if in a state belonging to
	`accepts`, it returns the corresponding token, else ERROR_TOKEN.
	"""
	
	# initial state
	pos = 0
	state = 's0'
	# memory for last seen accepting states
	last_token = None
	last_pos = None
	
	
	while True:
		
		c = getchar(text,pos)	# get next char (category)
		
		if state in transitions and c in transitions[state]:
			state = transitions[state][c]	# set new state
			pos += 1	# advance to next char
			
			# remember if current state is accepting
			if state in accepts:
				last_token = accepts[state]
				last_pos = pos
			
		else:	# no transition found

			if last_token is not None:	# if an accepting state already met
				return last_token,last_pos
			
			# else, no accepting state met yet
			return 'ERROR_TOKEN',pos
			
	
# **Σημείο #1**: Αντικαταστήστε με το δικό σας λεξικό μεταβάσεων
transitions = { 
	's0': {'0': 's1', '1': 's1', '2': 's1', '3': 's2'},
	's1': {'0': 's3', '1': 's3', '2': 's3', '3': 's3', '4': 's3', '5': 's3', '6': 's3', '7': 's3', '8': 's3', '9': 's3'},
	's2': {'0': 's3', '1': 's3', '2': 's3', '3': 's3', '4': 's3', '5': 's3'},
	's3': {'0': 's4'},
	's4': {'0': 's5', '1': 's5', '2': 's5', '3': 's5', '4': 's5', '5': 's5', '6': 's5', '7': 's5', '8': 's5', '9': 's5'},
	's5': {'0': 's6', '1': 's6', '2': 's6', '3': 's6', '4': 's6', '5': 's6', '6': 's6', '7': 's6', '8': 's6', '9': 's6'},
	's6': {'K': 's7', 'M': 's8', 'G': 's9'},
	's7': {'T': 's10'},
	's8': {'P': 's11'},
	's9': {'0': 's12', '1': 's12', '2': 's12', '3': 's12', '4': 's12', '5': 's12', '6': 's12', '7': 's12', '8': 's12', '9': 's12'},
	's11': {'S': 's10'},
	's12': {'0': 's13', '1': 's13', '2': 's13', '3': 's13', '4': 's13', '5': 's13', '6': 's13', '7': 's13', '8': 's13', '9': 's13'},
	's13': {'M': 's8', 'K': 's7'}
} 

# **Σημείο #2**: Αντικαταστήστε με το δικό σας λεξικό καταστάσεων αποδοχής
accepts = { 's10':'WIND_TOKEN' }


# get a string from input
text = input('give some input>')

# scan text until no more input
while text:		# i.e. len(text)>0
	# get next token and position after last char recognized
	token,pos = scan(text,transitions,accepts)
	if token=='ERROR_TOKEN':
		print('unrecognized input at position',pos,'of',text)
		break
	print("token:",token,"text:",text[:pos])
	# new text for next scan
	text = text[pos:]