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// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
#if !defined(CPPLINQ_LINQ_WHERE_HPP)
#define CPPLINQ_LINQ_WHERE_HPP
#pragma once
namespace cpplinq
{
template <class Collection, class Predicate>
class linq_where
{
typedef typename Collection::cursor
inner_cursor;
public:
struct cursor {
typedef typename util::min_iterator_category<
bidirectional_cursor_tag,
typename inner_cursor::cursor_category>::type
cursor_category;
typedef typename inner_cursor::element_type
element_type;
typedef typename inner_cursor::reference_type
reference_type;
cursor(const inner_cursor& cur, const Predicate& p) : cur(cur), pred(p)
{
if (!cur.empty() && !pred(cur.get())) {
this->inc();
}
}
void forget() { cur.forget(); }
bool empty() const { return cur.empty(); }
void inc() {
for (;;) {
cur.inc();
if (cur.empty() || pred(cur.get())) break;
}
}
reference_type get() const {
return cur.get();
}
bool atbegin() const { return atbegin(cur); }
void dec() {
for (;;) {
cur.dec();
if (pred(cur.get())) break;
}
}
private:
inner_cursor cur;
Predicate pred;
};
linq_where(const Collection& c, Predicate pred) : c(c), pred(pred) {}
cursor get_cursor() const {
return cursor(c.get_cursor(), pred);
}
private:
Collection c;
Predicate pred;
};
}
#endif // !defined(CPPLINQ_LINQ_WHERE_HPP)
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