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boost::xpressive::after — Look-behind assertion.
// In header: <boost/xpressive/regex_primitives.hpp> template<typename Expr> unspecified after(Expr const & expr);
after(expr) succeeds if the expr sub-expression would match at the current position minus N in the sequence, where N is the width of expr. expr is not included in the match. For instance, after("foo") succeeds if we are after a "foo". Look-behind assertions can be negated with the bit-complement operator.
| ![[Note]](../../../../doc/src/images/note.png) | Note | 
|---|---|
| after(expr) is equivalent to the perl (?<=...) extension. ~after(expr) is a negative look-behind assertion, equivalent to the perl (?<!...) extension. | 
| Parameters: | 
 | ||
| Requires: | expr cannot match a variable number of characters. |