3 ms·
I wonder why regex libraries don't do this then? Isn't /\s+$/ backreference free? Or does including the anchor change that?
by onetwotree 10y ago
I wonder why regex libraries don't do this then? Isn't /\s+$/ backreference free? Or does including the anchor change that?
- thaumasiotes 10y agoIt's backreference free. Backtracking to process it is just bad design. Here's a state machine that recognizes /^.*\s+$/: 1: initial state (non-matching) 2: matching state all states transition to 2 on \s, and to 1 on \S. Done. Taking this a little further, we can observe that since the transition table is identical for every state, there's no real need to have states at all -- you get the same effect by just checking the last character.