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In the description of generator expressions, the following notation is used:
fwdRng is an expression
of a type R that models
ForwardRange
biRng is an expression
of a type R that models
BidirectionalRange
rndRng is an expression
of a type R that models
RandomAccessRange
pred is an expression
of a type that models UnaryPredicate
bi_pred is an expression
of a type that models BinaryPredicate
fun is an expression
of a type that models UnaryFunction
value, new_value and old_value
are objects convertible to boost::range_value<R>::type
n,m are integer expressions convertible
to range_difference<R>::type
Also note that boost::range_value<R>::type must be implicitly convertible to
the type arguments to pred,
bi_pred and fun.
Range Category in the following adaptor descriptions refers to the minimum range concept required by the range passed to the adaptor. The resultant range is a model of the same range concept as the input range unless specified otherwise.
Returned Range Category is the concept of the returned range. In some cases
the returned range is of a lesser category than the range passed to the
adaptor. For example, the filtered
adaptor returns only a ForwardRange
regardless of the input.
Furthermore, the following rules apply to any expression of the form
rng | boost::adaptors::adaptor_generator
1. Applying operator|()
to a range R (always left
argument) and a range adapter RA
(always right argument) yields a new range type which may not conform to
the same range concept as R.
2. The return-type of operator|() is otherwise unspecified.
3. operator|()
is found by Argument Dependent Lookup (ADL) because a range adaptor is
implemented in namespace boost::adaptors.
4. operator|()
is used to add new behaviour lazily
and never modifies its left argument.
5. All iterators extracted from the left argument are extracted using qualified
calls to boost::begin()
and boost::end().
6. In addition to the throw-clauses
below, operator|()
may throw exceptions as a result of copying iterators. If such copying
cannot throw an exception, then neither can the whole expression.