2010-04-28 16:09:03 +00:00
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< div class = "section" title = "Class sub_range" >
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< a name = "range.reference.utilities.sub_range" > < / a > < a class = "link" href = "sub_range.html" title = "Class sub_range" > Class < code class = "computeroutput" > < span class = "identifier" > sub_range< / span > < / code > < / a >
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The < code class = "computeroutput" > < span class = "identifier" > sub_range< / span > < / code > class inherits
all its functionality from the < a class = "link" href = "iterator_range.html" title = "Class iterator_range" > < code class = "computeroutput" > < span class = "identifier" > iterator_range< / span > < / code > < / a > class. The < code class = "computeroutput" > < span class = "identifier" > sub_range< / span > < / code > class is often easier to use
because one must specify the < a class = "link" href = "../../concepts/forward_range.html" title = "Forward Range" > Forward
Range< / a > template argument instead of an iterator. Moreover, the < code class = "computeroutput" > < span class = "identifier" > sub_range< / span > < / code > class can propagate constness
since it knows what a corresponding < code class = "computeroutput" > < span class = "identifier" > const_iterator< / span > < / code >
is.
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< a name = "range.reference.utilities.sub_range.synopsis" > < / a > < h5 >
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< a name = "id2800752" > < / a >
2010-04-28 16:09:03 +00:00
< a class = "link" href = "sub_range.html#range.reference.utilities.sub_range.synopsis" > Synopsis< / a >
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< pre class = "programlisting" > < span class = "keyword" > namespace< / span > < span class = "identifier" > boost< / span >
< span class = "special" > {< / span >
< span class = "keyword" > template< / span > < span class = "special" > < < / span > < span class = "keyword" > class< / span > < span class = "identifier" > ForwardRange< / span > < span class = "special" > > < / span >
< span class = "keyword" > class< / span > < span class = "identifier" > sub_range< / span > < span class = "special" > :< / span > < span class = "keyword" > public< / span > < span class = "identifier" > iterator_range< / span > < span class = "special" > < < / span > < span class = "keyword" > typename< / span > < span class = "identifier" > range_iterator< / span > < span class = "special" > < < / span > < span class = "identifier" > ForwardRange< / span > < span class = "special" > > ::< / span > < span class = "identifier" > type< / span > < span class = "special" > > < / span >
< span class = "special" > {< / span >
< span class = "keyword" > public< / span > < span class = "special" > :< / span >
< span class = "keyword" > typedef< / span > < span class = "keyword" > typename< / span > < span class = "identifier" > range_iterator< / span > < span class = "special" > < < / span > < span class = "identifier" > ForwardRange< / span > < span class = "special" > > ::< / span > < span class = "identifier" > type< / span > < span class = "identifier" > iterator< / span > < span class = "special" > ;< / span >
< span class = "keyword" > typedef< / span > < span class = "keyword" > typename< / span > < span class = "identifier" > range_iterator< / span > < span class = "special" > < < / span > < span class = "keyword" > const< / span > < span class = "identifier" > ForwardRange< / span > < span class = "special" > > ::< / span > < span class = "identifier" > type< / span > < span class = "identifier" > const_iterator< / span > < span class = "special" > ;< / span >
< span class = "keyword" > typedef< / span > < span class = "keyword" > typename< / span > < span class = "identifier" > iterator_difference< / span > < span class = "special" > < < / span > < span class = "identifier" > iterator< / span > < span class = "special" > > ::< / span > < span class = "identifier" > type< / span > < span class = "identifier" > difference_type< / span > < span class = "special" > ;< / span >
< span class = "keyword" > public< / span > < span class = "special" > :< / span > < span class = "comment" > // construction, assignment
< / span > < span class = "keyword" > template< / span > < span class = "special" > < < / span > < span class = "keyword" > class< / span > < span class = "identifier" > ForwardTraversalIterator< / span > < span class = "special" > > < / span >
< span class = "identifier" > sub_range< / span > < span class = "special" > (< / span > < span class = "identifier" > ForwardTraversalIterator< / span > < span class = "identifier" > Begin< / span > < span class = "special" > ,< / span > < span class = "identifier" > ForwardTraversalIterator< / span > < span class = "identifier" > End< / span > < span class = "special" > );< / span >
< span class = "keyword" > template< / span > < span class = "special" > < < / span > < span class = "keyword" > class< / span > < span class = "identifier" > ForwardRange2< / span > < span class = "special" > > < / span >
< span class = "identifier" > sub_range< / span > < span class = "special" > (< / span > < span class = "identifier" > ForwardRange2< / span > < span class = "special" > & < / span > < span class = "identifier" > r< / span > < span class = "special" > );< / span >
< span class = "keyword" > template< / span > < span class = "special" > < < / span > < span class = "keyword" > class< / span > < span class = "identifier" > ForwardRange2< / span > < span class = "special" > > < / span >
< span class = "identifier" > sub_range< / span > < span class = "special" > (< / span > < span class = "keyword" > const< / span > < span class = "identifier" > Range2< / span > < span class = "special" > & < / span > < span class = "identifier" > r< / span > < span class = "special" > );< / span >
< span class = "keyword" > template< / span > < span class = "special" > < < / span > < span class = "keyword" > class< / span > < span class = "identifier" > ForwardRange2< / span > < span class = "special" > > < / span >
< span class = "identifier" > sub_range< / span > < span class = "special" > & < / span > < span class = "keyword" > operator< / span > < span class = "special" > =(< / span > < span class = "identifier" > ForwardRange2< / span > < span class = "special" > & < / span > < span class = "identifier" > r< / span > < span class = "special" > );< / span >
< span class = "keyword" > template< / span > < span class = "special" > < < / span > < span class = "keyword" > class< / span > < span class = "identifier" > ForwardRange2< / span > < span class = "special" > > < / span >
< span class = "identifier" > sub_range< / span > < span class = "special" > & < / span > < span class = "keyword" > operator< / span > < span class = "special" > =(< / span > < span class = "keyword" > const< / span > < span class = "identifier" > ForwardRange2< / span > < span class = "special" > & < / span > < span class = "identifier" > r< / span > < span class = "special" > );< / span >
< span class = "keyword" > public< / span > < span class = "special" > :< / span > < span class = "comment" > // Forward Range functions
< / span > < span class = "identifier" > iterator< / span > < span class = "identifier" > begin< / span > < span class = "special" > ();< / span >
< span class = "identifier" > const_iterator< / span > < span class = "identifier" > begin< / span > < span class = "special" > ()< / span > < span class = "keyword" > const< / span > < span class = "special" > ;< / span >
< span class = "identifier" > iterator< / span > < span class = "identifier" > end< / span > < span class = "special" > ();< / span >
< span class = "identifier" > const_iterator< / span > < span class = "identifier" > end< / span > < span class = "special" > ()< / span > < span class = "keyword" > const< / span > < span class = "special" > ;< / span >
< span class = "keyword" > public< / span > < span class = "special" > :< / span > < span class = "comment" > // convenience
< / span > < span class = "identifier" > value_type< / span > < span class = "special" > & < / span > < span class = "identifier" > front< / span > < span class = "special" > ();< / span >
< span class = "keyword" > const< / span > < span class = "identifier" > value_type< / span > < span class = "special" > & < / span > < span class = "identifier" > front< / span > < span class = "special" > ()< / span > < span class = "keyword" > const< / span > < span class = "special" > ;< / span >
< span class = "identifier" > value_type< / span > < span class = "special" > & < / span > < span class = "identifier" > back< / span > < span class = "special" > ();< / span >
< span class = "keyword" > const< / span > < span class = "identifier" > value_type< / span > < span class = "special" > & < / span > < span class = "identifier" > back< / span > < span class = "special" > ()< / span > < span class = "keyword" > const< / span > < span class = "special" > ;< / span >
< span class = "comment" > // for Random Access Range only:
< / span > < span class = "identifier" > value_type< / span > < span class = "special" > & < / span > < span class = "keyword" > operator< / span > < span class = "special" > [](< / span > < span class = "identifier" > size_type< / span > < span class = "identifier" > at< / span > < span class = "special" > );< / span >
< span class = "keyword" > const< / span > < span class = "identifier" > value_type< / span > < span class = "special" > & < / span > < span class = "keyword" > operator< / span > < span class = "special" > [](< / span > < span class = "identifier" > size_type< / span > < span class = "identifier" > at< / span > < span class = "special" > )< / span > < span class = "keyword" > const< / span > < span class = "special" > ;< / span >
< span class = "keyword" > public< / span > < span class = "special" > :< / span >
< span class = "comment" > // rest of interface inherited from iterator_range
< / span > < span class = "special" > };< / span >
< span class = "special" > }< / span > < span class = "comment" > // namespace 'boost'
< / span > < / pre >
< p >
< / p >
< p >
The class should be trivial to use as seen below. Imagine that we have
an algorithm that searches for a sub-string in a string. The result is
an iterator_range, that delimits the match. We need to store the result
from this algorithm. Here is an example of how we can do it with and without
< code class = "computeroutput" > < span class = "identifier" > sub_range< / span > < / code >
< / p >
< p >
< / p >
< pre class = "programlisting" > < span class = "identifier" > std< / span > < span class = "special" > ::< / span > < span class = "identifier" > string< / span > < span class = "identifier" > str< / span > < span class = "special" > (< / span > < span class = "string" > "hello"< / span > < span class = "special" > );< / span >
< span class = "identifier" > iterator_range< / span > < span class = "special" > < < / span > < span class = "identifier" > std< / span > < span class = "special" > ::< / span > < span class = "identifier" > string< / span > < span class = "special" > ::< / span > < span class = "identifier" > iterator< / span > < span class = "special" > > < / span > < span class = "identifier" > ir< / span > < span class = "special" > =< / span > < span class = "identifier" > find_first< / span > < span class = "special" > (< / span > < span class = "identifier" > str< / span > < span class = "special" > ,< / span > < span class = "string" > "ll"< / span > < span class = "special" > );< / span >
< span class = "identifier" > sub_range< / span > < span class = "special" > < < / span > < span class = "identifier" > std< / span > < span class = "special" > ::< / span > < span class = "identifier" > string< / span > < span class = "special" > > < / span > < span class = "identifier" > sub< / span > < span class = "special" > =< / span > < span class = "identifier" > find_first< / span > < span class = "special" > (< / span > < span class = "identifier" > str< / span > < span class = "special" > ,< / span > < span class = "string" > "ll"< / span > < span class = "special" > );< / span >
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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