Greedy vs. Reluctant vs. Possessive Quantifiers

Question

I found this excellent tutorial on regular expressions and while I intuitively understand what \"greedy\", \"reluctant\" and \"possessive\" quantifiers do, there seems to be

Answer 1

Greedy Quantification involves pattern matching using all of the remaining unvalidated characters of a string during an iteration. Unvalidated characters start in the active sequence. Every time a match does not occur, the character at the end is quarantined and the check is performed again.

When only leading conditions of the regex pattern are satisfied by the active sequence, an attempt is made to validate the remaining conditions against the quarantine. If this validation is successful, matched characters in the quarantine are validated and residual unmatched characters remain unvalidated and will be used when the process begins anew in the next iteration.

The flow of characters is from the active sequence into the quarantine. The resulting behavior is that as much of the original sequence is included in a match as possible.

Reluctant Quantification is mostly the same as greedy qualification except the flow of characters is the opposite--that is, they start in the quarantine and flow into the active sequence. The resulting behavior is that as little of the original sequence is included in a match as possible.

Possessive Quantification does not have a quarantine and includes everything in a fixed active sequence.