both of these approaches use NFAs under the hood, which means O(m * n) matching. our approach is fundamentally different: we encode lookaround information directly in the automaton via derivatives, which gives us O(n) matching with a small constant. the trade-off is that we restrict lookarounds to a normalized form (?<=R1)R2(?=R3) where R1/R2/R3 themselves don’t contain lookarounds. the oracle-based approaches support more general nesting, but pay for it in the matching loop. one open question i have is how they handle memory for the oracle table - if you read a gigabyte of text, do you keep a gigabyte-sized table in memory for each lookaround in the pattern?
FirstFT: the day's biggest stories
，这一点在爱思助手中也有详细论述
NASA wrote a statement saying that the astronaut experienced an unknown medical event on January 7 "that required immediate attention" from his fellow crew members. Fincke added that his "status quickly stabilized" thanks to the "quick response and the guidance" of the flight surgeons.
Express(absent)