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-rw-r--r--butl/prefix-map138
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diff --git a/butl/prefix-map b/butl/prefix-map
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-// file : butl/prefix-map -*- C++ -*-
-// copyright : Copyright (c) 2014-2017 Code Synthesis Ltd
-// license : MIT; see accompanying LICENSE file
-
-#ifndef BUTL_PREFIX_MAP
-#define BUTL_PREFIX_MAP
-
-#include <map>
-#include <string>
-#include <utility> // move()
-#include <algorithm> // min()
-
-namespace butl
-{
- // A map of hierarchical "paths", e.g., 'foo.bar' or 'foo/bar' with
- // the ability to retrieve a range of entries that have a specific
- // prefix. The '.' and '/' above are the delimiter characters.
- //
- // Note that as a special rule, the default implementation of
- // compare_prefix treats empty key as everyone's prefix even if
- // the paths don't start with the delimiter (useful to represent
- // a "root path").
- //
- // Implementation-wise, the idea is to pretend that each key ends
- // with the delimiter. This way we automatically avoid matching
- // 'foobar' as having a prefix 'foo'.
- //
- template <typename K>
- struct compare_prefix;
-
- template <typename C>
- struct compare_prefix<std::basic_string<C>>
- {
- typedef std::basic_string<C> K;
-
- typedef C delimiter_type;
- typedef typename K::size_type size_type;
- typedef typename K::traits_type traits_type;
-
- explicit
- compare_prefix (delimiter_type d): d_ (d) {}
-
- bool
- operator() (const K& x, const K& y) const
- {
- return compare (x.c_str (), x.size (), y.c_str (), y.size ()) < 0;
- }
-
- bool
- prefix (const K& p, const K& k) const
- {
- size_type pn (p.size ()), kn (k.size ());
- return pn == 0 || // Empty key is always a prefix.
- (pn <= kn &&
- compare (p.c_str (), pn, k.c_str (), pn == kn ? pn : pn + 1) == 0);
- }
-
- protected:
- int
- compare (const C* x, size_type xn,
- const C* y, size_type yn) const
- {
- size_type n (std::min (xn, yn));
- int r (traits_type::compare (x, y, n));
-
- if (r == 0)
- {
- // Pretend there is the delimiter characters at the end of the
- // shorter string.
- //
- char xc (xn > n ? x[n] : (xn++, d_));
- char yc (yn > n ? y[n] : (yn++, d_));
- r = traits_type::compare (&xc, &yc, 1);
-
- // If we are still equal, then compare the lengths.
- //
- if (r == 0)
- r = (xn == yn ? 0 : (xn < yn ? -1 : 1));
- }
-
- return r;
- }
-
- private:
- delimiter_type d_;
- };
-
- template <typename M>
- struct prefix_map_common: M
- {
- typedef M map_type;
- typedef typename map_type::key_type key_type;
- typedef typename map_type::value_type value_type;
- typedef typename map_type::key_compare compare_type;
- typedef typename compare_type::delimiter_type delimiter_type;
-
- typedef typename map_type::iterator iterator;
- typedef typename map_type::const_iterator const_iterator;
-
- explicit
- prefix_map_common (delimiter_type d)
- : map_type (compare_type (d)) {}
-
- prefix_map_common (std::initializer_list<value_type> i, delimiter_type d)
- : map_type (std::move (i), compare_type (d)) {}
-
- std::pair<iterator, iterator>
- find_prefix (const key_type&);
-
- std::pair<const_iterator, const_iterator>
- find_prefix (const key_type&) const;
- };
-
- template <typename M, typename prefix_map_common<M>::delimiter_type D>
- struct prefix_map_impl: prefix_map_common<M>
- {
- typedef typename prefix_map_common<M>::value_type value_type;
-
- prefix_map_impl (): prefix_map_common<M> (D) {}
- prefix_map_impl (std::initializer_list<value_type> i)
- : prefix_map_common<M> (std::move (i), D) {}
- };
-
- template <typename K,
- typename T,
- typename compare_prefix<K>::delimiter_type D>
- using prefix_map = prefix_map_impl<std::map<K, T, compare_prefix<K>>, D>;
-
- template <typename K,
- typename T,
- typename compare_prefix<K>::delimiter_type D>
- using prefix_multimap =
- prefix_map_impl<std::multimap<K, T, compare_prefix<K>>, D>;
-}
-
-#include <butl/prefix-map.txx>
-
-#endif // BUTL_PREFIX_MAP