generic-library/cxx
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Implementation of Boyer-Moore and Boyer-Moore-Horspool searchers for the LFTS.

Browse Source 
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@247036 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Marshall Clow
2015-09-08 17:59:09 +00:00
parent 65a6f64221
commit af9a44f256
11 changed files with 1360 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

327
include/experimental/functional
View File

@@ -20,7 +20,7 @@ namespace std {
namespace experimental {
inline namespace fundamentals_v1 {
// See C++14 §20.9.9, Function object binders
// See C++14 20.9.9, Function object binders
template <class T> constexpr bool is_bind_expression_v
= is_bind_expression<T>::value;
template <class T> constexpr int is_placeholder_v
@@ -89,7 +89,12 @@ inline namespace fundamentals_v1 {
#include <experimental/__config>
#include <functional>
#include <algorithm>
#include <type_traits>
#include <vector>
#include <array>
#include <unordered_map>
#include <__undef_min_max>
@@ -101,18 +106,23 @@ inline namespace fundamentals_v1 {
_LIBCPP_BEGIN_NAMESPACE_LFTS
#if _LIBCPP_STD_VER > 11
// default searcher
template<class _ForwardIterator, class _BinaryPredicate = equal_to<>>
_LIBCPP_TYPE_VIS
class default_searcher {
public:
_LIBCPP_INLINE_VISIBILITY
default_searcher(_ForwardIterator __f, _ForwardIterator __l,
_BinaryPredicate __p = _BinaryPredicate())
: __first_(__f), __last_(__l), __pred_(__p) {}
template <typename _ForwardIterator2>
_ForwardIterator2 operator () (_ForwardIterator2 __f, _ForwardIterator2 __l) const {
_LIBCPP_INLINE_VISIBILITY
_ForwardIterator2 operator () (_ForwardIterator2 __f, _ForwardIterator2 __l) const
{
return _VSTD::search(__f, __l, __first_, __last_, __pred_);
}
}
private:
_ForwardIterator __first_;
@@ -121,12 +131,323 @@ private:
};
template<class _ForwardIterator, class _BinaryPredicate = equal_to<>>
_LIBCPP_INLINE_VISIBILITY
default_searcher<_ForwardIterator, _BinaryPredicate>
make_default_searcher( _ForwardIterator __f, _ForwardIterator __l, _BinaryPredicate __p = _BinaryPredicate ())
{
return default_searcher<_ForwardIterator, _BinaryPredicate>(__f, __l, __p);
}
template<class _Key, class _Value, class _Hash, class _BinaryPredicate, bool /*useArray*/> class _BMSkipTable;
// General case for BM data searching; use a map
template<class _Key, typename _Value, class _Hash, class _BinaryPredicate>
class _BMSkipTable<_Key, _Value, _Hash, _BinaryPredicate, false> {
public: // TODO private:
typedef _Value value_type;
typedef _Key key_type;
const _Value __default_value_;
std::unordered_map<_Key, _Value, _Hash, _BinaryPredicate> __table;
public:
_LIBCPP_INLINE_VISIBILITY
_BMSkipTable(std::size_t __sz, _Value __default, _Hash __hf, _BinaryPredicate __pred)
: __default_value_(__default), __table(__sz, __hf, __pred) {}
_LIBCPP_INLINE_VISIBILITY
void insert(const key_type &__key, value_type __val)
{
__table [__key] = __val; // Would skip_.insert (val) be better here?
}
_LIBCPP_INLINE_VISIBILITY
value_type operator [](const key_type & __key) const
{
auto __it = __table.find (__key);
return __it == __table.end() ? __default_value_ : __it->second;
}
};
// Special case small numeric values; use an array
template<class _Key, typename _Value, class _Hash, class _BinaryPredicate>
class _BMSkipTable<_Key, _Value, _Hash, _BinaryPredicate, true> {
private:
typedef _Value value_type;
typedef _Key key_type;
typedef typename std::make_unsigned<key_type>::type unsigned_key_type;
typedef std::array<value_type, _VSTD::numeric_limits<unsigned_key_type>::max()> skip_map;
skip_map __table;
public:
_LIBCPP_INLINE_VISIBILITY
_BMSkipTable(std::size_t /*__sz*/, _Value __default, _Hash /*__hf*/, _BinaryPredicate /*__pred*/)
{
std::fill_n(__table.begin(), __table.size(), __default);
}
_LIBCPP_INLINE_VISIBILITY
void insert(key_type __key, value_type __val)
{
__table[static_cast<unsigned_key_type>(__key)] = __val;
}
_LIBCPP_INLINE_VISIBILITY
value_type operator [](key_type __key) const
{
return __table[static_cast<unsigned_key_type>(__key)];
}
};
template <class _RandomAccessIterator1,
class _Hash = hash<typename iterator_traits<_RandomAccessIterator1>::value_type>,
class _BinaryPredicate = equal_to<>>
_LIBCPP_TYPE_VIS
class boyer_moore_searcher {
private:
typedef typename std::iterator_traits<_RandomAccessIterator1>::difference_type difference_type;
typedef typename std::iterator_traits<_RandomAccessIterator1>::value_type value_type;
typedef _BMSkipTable<value_type, difference_type, _Hash, _BinaryPredicate,
_VSTD::is_integral<value_type>::value && // what about enums?
sizeof(value_type) == 1 &&
is_same<_Hash, hash<value_type>>::value &&
is_same<_BinaryPredicate, equal_to<>>::value
> skip_table_type;
public:
boyer_moore_searcher(_RandomAccessIterator1 __f, _RandomAccessIterator1 __l,
_Hash __hf = _Hash(), _BinaryPredicate __pred = _BinaryPredicate())
: __first_(__f), __last_(__l), __pred_(__pred),
__pattern_length_(_VSTD::distance(__first_, __last_)),
__skip_{make_shared<skip_table_type>(__pattern_length_, -1, __hf, __pred_)},
__suffix_{make_shared<vector<difference_type>>(__pattern_length_ + 1)}
{
// build the skip table
for ( difference_type __i = 0; __f != __l; ++__f, (void) ++__i )
__skip_->insert(*__f, __i);
this->__build_suffix_table ( __first_, __last_, __pred_ );
}
template <typename _RandomAccessIterator2>
_RandomAccessIterator2
operator ()(_RandomAccessIterator2 __f, _RandomAccessIterator2 __l) const
{
static_assert ( std::is_same<
typename std::decay<typename std::iterator_traits<_RandomAccessIterator1>::value_type>::type,
typename std::decay<typename std::iterator_traits<_RandomAccessIterator2>::value_type>::type
>::value,
"Corpus and Pattern iterators must point to the same type" );
if (__f == __l ) return __l; // empty corpus
if (__first_ == __last_) return __f; // empty pattern
// If the pattern is larger than the corpus, we can't find it!
if ( __pattern_length_ > _VSTD::distance (__f, __l))
return __l;
// Do the search
return this->__search(__f, __l);
}
public: // TODO private:
_RandomAccessIterator1 __first_;
_RandomAccessIterator1 __last_;
_BinaryPredicate __pred_;
difference_type __pattern_length_;
shared_ptr<skip_table_type> __skip_;
shared_ptr<vector<difference_type>> __suffix_;
template <typename _RandomAccessIterator2>
_RandomAccessIterator2 __search(_RandomAccessIterator2 __f, _RandomAccessIterator2 __l) const
{
_RandomAccessIterator2 __cur = __f;
const _RandomAccessIterator2 __last = __l - __pattern_length_;
const skip_table_type & __skip = *__skip_.get();
const vector<difference_type> & __suffix = *__suffix_.get();
while (__cur <= __last)
{
// Do we match right where we are?
difference_type __j = __pattern_length_;
while (__pred_(__first_ [__j-1], __cur [__j-1])) {
__j--;
// We matched - we're done!
if ( __j == 0 )
return __cur;
}
// Since we didn't match, figure out how far to skip forward
difference_type __k = __skip[__cur [ __j - 1 ]];
difference_type __m = __j - __k - 1;
if (__k < __j && __m > __suffix[ __j ])
__cur += __m;
else
__cur += __suffix[ __j ];
}
return __l; // We didn't find anything
}
template<typename _Iterator, typename _Container>
void __compute_bm_prefix ( _Iterator __f, _Iterator __l, _BinaryPredicate __pred, _Container &__prefix )
{
const std::size_t __count = _VSTD::distance(__f, __l);
__prefix[0] = 0;
std::size_t __k = 0;
for ( std::size_t __i = 1; __i < __count; ++__i )
{
while ( __k > 0 && !__pred ( __f[__k], __f[__i] ))
__k = __prefix [ __k - 1 ];
if ( __pred ( __f[__k], __f[__i] ))
__k++;
__prefix [ __i ] = __k;
}
}
void __build_suffix_table(_RandomAccessIterator1 __f, _RandomAccessIterator1 __l,
_BinaryPredicate __pred)
{
const std::size_t __count = _VSTD::distance(__f, __l);
vector<difference_type> & __suffix = *__suffix_.get();
if (__count > 0)
{
_VSTD::vector<value_type> __scratch(__count);
__compute_bm_prefix(__f, __l, __pred, __scratch);
for ( std::size_t __i = 0; __i <= __count; __i++ )
__suffix[__i] = __count - __scratch[__count-1];
typedef _VSTD::reverse_iterator<_RandomAccessIterator1> _RevIter;
__compute_bm_prefix(_RevIter(__l), _RevIter(__f), __pred, __scratch);
for ( std::size_t __i = 0; __i < __count; __i++ )
{
const std::size_t __j = __count - __scratch[__i];
const difference_type __k = __i - __scratch[__i] + 1;
if (__suffix[__j] > __k)
__suffix[__j] = __k;
}
}
}
};
template<class _RandomAccessIterator,
class _Hash = hash<typename iterator_traits<_RandomAccessIterator>::value_type>,
class _BinaryPredicate = equal_to<>>
_LIBCPP_INLINE_VISIBILITY
boyer_moore_searcher<_RandomAccessIterator, _Hash, _BinaryPredicate>
make_boyer_moore_searcher( _RandomAccessIterator __f, _RandomAccessIterator __l,
_Hash __hf = _Hash(), _BinaryPredicate __p = _BinaryPredicate ())
{
return boyer_moore_searcher<_RandomAccessIterator, _Hash, _BinaryPredicate>(__f, __l, __hf, __p);
}
// boyer-moore-horspool
template <class _RandomAccessIterator1,
class _Hash = hash<typename iterator_traits<_RandomAccessIterator1>::value_type>,
class _BinaryPredicate = equal_to<>>
_LIBCPP_TYPE_VIS
class boyer_moore_horspool_searcher {
private:
typedef typename std::iterator_traits<_RandomAccessIterator1>::difference_type difference_type;
typedef typename std::iterator_traits<_RandomAccessIterator1>::value_type value_type;
typedef _BMSkipTable<value_type, difference_type, _Hash, _BinaryPredicate,
_VSTD::is_integral<value_type>::value && // what about enums?
sizeof(value_type) == 1 &&
is_same<_Hash, hash<value_type>>::value &&
is_same<_BinaryPredicate, equal_to<>>::value
> skip_table_type;
public:
boyer_moore_horspool_searcher(_RandomAccessIterator1 __f, _RandomAccessIterator1 __l,
_Hash __hf = _Hash(), _BinaryPredicate __pred = _BinaryPredicate())
: __first_(__f), __last_(__l), __pred_(__pred),
__pattern_length_(_VSTD::distance(__first_, __last_)),
__skip_{_VSTD::make_shared<skip_table_type>(__pattern_length_, __pattern_length_, __hf, __pred_)}
{
// build the skip table
if ( __f != __l )
{
__l = __l - 1;
for ( difference_type __i = 0; __f != __l; ++__f, (void) ++__i )
__skip_->insert(*__f, __pattern_length_ - 1 - __i);
}
}
template <typename _RandomAccessIterator2>
_RandomAccessIterator2
operator ()(_RandomAccessIterator2 __f, _RandomAccessIterator2 __l) const
{
static_assert ( std::is_same<
typename std::decay<typename std::iterator_traits<_RandomAccessIterator1>::value_type>::type,
typename std::decay<typename std::iterator_traits<_RandomAccessIterator2>::value_type>::type
>::value,
"Corpus and Pattern iterators must point to the same type" );
if (__f == __l ) return __l; // empty corpus
if (__first_ == __last_) return __f; // empty pattern
// If the pattern is larger than the corpus, we can't find it!
if ( __pattern_length_ > _VSTD::distance (__f, __l))
return __l;
// Do the search
return this->__search(__f, __l);
}
private:
_RandomAccessIterator1 __first_;
_RandomAccessIterator1 __last_;
_BinaryPredicate __pred_;
difference_type __pattern_length_;
shared_ptr<skip_table_type> __skip_;
template <typename _RandomAccessIterator2>
_RandomAccessIterator2 __search ( _RandomAccessIterator2 __f, _RandomAccessIterator2 __l ) const {
_RandomAccessIterator2 __cur = __f;
const _RandomAccessIterator2 __last = __l - __pattern_length_;
const skip_table_type & __skip = *__skip_.get();
while (__cur <= __last)
{
// Do we match right where we are?
difference_type __j = __pattern_length_;
while (__pred_(__first_[__j-1], __cur[__j-1]))
{
__j--;
// We matched - we're done!
if ( __j == 0 )
return __cur;
}
__cur += __skip[__cur[__pattern_length_-1]];
}
return __l;
}
};
template<class _RandomAccessIterator,
class _Hash = hash<typename iterator_traits<_RandomAccessIterator>::value_type>,
class _BinaryPredicate = equal_to<>>
_LIBCPP_INLINE_VISIBILITY
boyer_moore_horspool_searcher<_RandomAccessIterator, _Hash, _BinaryPredicate>
make_boyer_moore_horspool_searcher( _RandomAccessIterator __f, _RandomAccessIterator __l,
_Hash __hf = _Hash(), _BinaryPredicate __p = _BinaryPredicate ())
{
return boyer_moore_horspool_searcher<_RandomAccessIterator, _Hash, _BinaryPredicate>(__f, __l, __hf, __p);
}
#endif // _LIBCPP_STD_VER > 11
_LIBCPP_END_NAMESPACE_LFTS