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Simplify counting iterators

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This commit is contained in:
Victor Zverovich
2018-03-31 07:47:30 -10:00
parent e8e006f4e7
commit 4975297eb0
1 changed files with 15 additions and 15 deletions
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30
include/fmt/format.h
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@ -702,7 +702,7 @@ FMT_CONSTEXPR const Char *pointer_from(null_terminating_iterator<Char> it) {
template <typename T> template <typename T>
class counting_iterator { class counting_iterator {
private: private:
std::size_t* count_; std::size_t count_;
mutable T blackhole_; mutable T blackhole_;
public: public:
@ -712,10 +712,12 @@ class counting_iterator {
typedef T* pointer; typedef T* pointer;
typedef T& reference; typedef T& reference;
explicit counting_iterator(std::size_t &count): count_(&count) {} counting_iterator(): count_(0) {}
std::size_t count() const { return count_; }
counting_iterator& operator++() { counting_iterator& operator++() {
++*count_; ++count_;
return *this; return *this;
} }
@ -733,7 +735,7 @@ class truncating_iterator {
OutputIt out_; OutputIt out_;
std::size_t limit_; std::size_t limit_;
std::size_t *count_; std::size_t count_;
mutable typename traits::value_type blackhole_; mutable typename traits::value_type blackhole_;
public: public:
@ -743,20 +745,21 @@ class truncating_iterator {
typedef typename traits::pointer pointer; typedef typename traits::pointer pointer;
typedef typename traits::reference reference; typedef typename traits::reference reference;
truncating_iterator(OutputIt out, std::size_t limit, std::size_t &count) truncating_iterator(OutputIt out, std::size_t limit)
: out_(out), limit_(limit), count_(&count) {} : out_(out), limit_(limit), count_(0) {}
OutputIt base() const { return out_; } OutputIt base() const { return out_; }
std::size_t count() const { return count_; }
truncating_iterator& operator++() { truncating_iterator& operator++() {
if ((*count_)++ < limit_) if (count_++ < limit_)
++out_; ++out_;
return *this; return *this;
} }
truncating_iterator operator++(int) { return ++*this; } truncating_iterator operator++(int) { return ++*this; }
reference operator*() const { return *count_ < limit_ ? *out_ : blackhole_; } reference operator*() const { return count_ < limit_ ? *out_ : blackhole_; }
}; };
// Returns true if value is negative, false otherwise. // Returns true if value is negative, false otherwise.
@ -3436,10 +3439,9 @@ template <typename OutputIt, typename... Args>
inline format_to_n_result<OutputIt> format_to_n( inline format_to_n_result<OutputIt> format_to_n(
OutputIt out, std::size_t n, string_view format_str, const Args & ... args) { OutputIt out, std::size_t n, string_view format_str, const Args & ... args) {
typedef internal::truncating_iterator<OutputIt> It; typedef internal::truncating_iterator<OutputIt> It;
std::size_t count = 0; auto it = vformat_to(It(out, n), format_str,
auto it = vformat_to(It(out, n, count), format_str,
*make_args<typename context_t<It>::type>(args...)); *make_args<typename context_t<It>::type>(args...));
return {it.base(), count}; return {it.base(), it.count()};
} }
inline std::string vformat(string_view format_str, format_args args) { inline std::string vformat(string_view format_str, format_args args) {
@ -3472,10 +3474,8 @@ inline typename std::enable_if<internal::is_format_string<String>::value>::type
// Counts the number of characters in the output of format(format_str, args...). // Counts the number of characters in the output of format(format_str, args...).
template <typename... Args> template <typename... Args>
inline std::size_t count(string_view format_str, const Args & ... args) { inline std::size_t count(string_view format_str, const Args & ... args) {
std::size_t size = 0; auto it = format_to(internal::counting_iterator<char>(), format_str, args...);
internal::counting_iterator<char> it(size); return it.count();
format_to(it, format_str, args...);
return size;
} }
} // namespace fmt } // namespace fmt