On 15.01.2016 12:04, Charles T. Smith wrote:
On Fri, 15 Jan 2016 11:42:24 +0100, Wolfgang Maier wrote:
On 15.01.2016 10:43, Peter Otten wrote:
Charles T. Smith wrote:
while ($str != $tail) {
$str ~= s/^(head-pattern)//;
use ($1);
}
....
things = []
while some_str != tail:
m = re.match(pattern_str, some_str)
things.append(some_str[:m.end()])
some_str = some_str[m.end():]
# do something with things
Okay, I guess it's not a lot more work to use the end() method to manually
cut out the found portion.
What the original snippet does is parse *and consume* a string - actually,
to avoid maintaining a cursor traverse the string. The perl feature is that
substitute allows the found pattern to be replaced, but retains the group
after the expression is complete.
The end() method is actually such a cursor, but already set up for you
by the class, and then the slicing considerably simplifies its use.
I see. If consuming the string is not essential for you, but just a
handy trick to avoid the cursor, you may prefer this (most likely
faster) solution:
pattern = pattern_str.compile()
try:
matches = pattern.findall(some_str, endpos=some_str.index(tail))
except ValueError:
# do something if tail is not found
pass
Best,
Wolfgang
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