Created
February 22, 2017 06:54
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# copy from https://docs.python.org/3.5/library/re.html | |
import collections | |
import re | |
Token = collections.namedtuple('Token', ['typ', 'value', 'line', 'column']) | |
def tokenize(code): | |
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 | |
('MISMATCH', r'.'), # Any other character | |
] | |
tok_regex = '|'.join('(?P<%s>%s)' % pair for pair in token_specification) | |
line_num = 1 | |
line_start = 0 | |
for mo in re.finditer(tok_regex, code): | |
kind = mo.lastgroup | |
value = mo.group(kind) | |
if kind == 'NEWLINE': | |
line_start = mo.end() | |
line_num += 1 | |
elif kind == 'SKIP': | |
pass | |
elif kind == 'MISMATCH': | |
raise RuntimeError('%r unexpected on line %d' % (value ,line_num)) | |
else: | |
if kind == 'ID' and value in keywords: | |
kind = value | |
column = mo.start() - line_start | |
yield Token(kind, value, line_num, column) | |
statements = ''' | |
IF quantity THEN | |
total := total + price * quantity; | |
tax := price * 0.05; | |
ENDIF; | |
''' | |
for token in tokenize(statements): | |
print(token) |
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