如何使前瞻非贪婪匹配?我希望第一种情况不要匹配任何内容(就像第二种情况一样),但它返回了“winnie”。我猜是因为它在“the”后面贪婪匹配了。
str <- "winnie the pooh bear"
## Unexpected
regmatches(str, gregexpr("winnie|bear(?= bear|pooh)", str, perl=T))
# [1] "winnie"
## Expected
regmatches(str, gregexpr("winnie(?= bear|pooh)", str, perl=T))
# character(0)