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textbook example solution in Clear category for I Love Python! by apotokin
import collections
import re
Token = collections.namedtuple('Token', ['typ', 'value', 'line', 'column'])
def tokenize(s):
keywords = {'IF', 'THEN', 'ENDIF', 'FOR', 'NEXT', 'GOSUB', 'RETURN'}
token_specification = [
('NUMBER', r'\d+(\.\d*)?'), # Integer or decimal number
('ASSIGN', r':='), # Assignment operator
('END', r';'), # Statement terminator
('ID', r'[A-Za-z]+'), # Identifiers
('OP', r'[+*\/\-]'), # Arithmetic operators
('NEWLINE', r'\n'), # Line endings
('SKIP', r'[ \t]'), # Skip over spaces and tabs
]
tok_regex = '|'.join('(?P<%s>%s)' % pair for pair in token_specification)
get_token = re.compile(tok_regex).match
line = 1
pos = line_start = 0
a_token = get_token(s)
while a_token is not None:
typ = a_token.lastgroup
if typ == 'NEWLINE':
line_start = pos
line += 1
elif typ != 'SKIP':
val = a_token.group(typ)
if typ == 'ID' and val in keywords:
typ = val
yield Token(typ, val, line, a_token.start()-line_start)
pos = a_token.end()
a_token = get_token(s, pos)
if pos != len(s):
raise RuntimeError('Unexpected character %r on line %d' %(s[pos], line))
statements = '''
IF quantity THEN
total := total + price * quantity;
tax := price * 0.05;
ENDIF;
'''
for token in tokenize(statements):
print(token)
def i_love_python():
return "I love Python!"
if __name__ == 'MYCODE':
#These "asserts" using only for self-checking and not necessary for auto-testing
assert i_love_python() == "I love Python!"
print('I do love python, but other serpents')
Aug. 2, 2015
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