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fully generic stream range (works on any type of stream)

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q66 2017-02-27 17:52:52 +01:00
parent 5beecdf370
commit e0574308a0
1 changed files with 23 additions and 17 deletions
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34
ostd/stream.hh
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@ -9,6 +9,7 @@
#include <sys/types.h>
#include <type_traits>
#include <locale>
#include <optional>
#include "ostd/platform.hh"
#include "ostd/types.hh"
@ -157,42 +158,47 @@ struct stream_range<T, true>: input_range<stream_range<T>> {
using difference_type = stream_off_t;
stream_range() = delete;
stream_range(stream &s): p_stream(&s), p_size(s.size()) {}
stream_range(stream_range const &r): p_stream(r.p_stream), p_size(r.p_size) {}
stream_range(stream &s): p_stream(&s) {}
stream_range(stream_range const &r): p_stream(r.p_stream) {}
bool empty() const {
if (!p_item.has_value()) {
try {
auto pos = p_stream->tell();
return (p_size - pos) < stream_off_t(sizeof(T));
p_item = p_stream->get<T>();
} catch (...) {
return true;
}
}
return false;
}
void pop_front() {
T val;
p_stream->read_bytes(&val, sizeof(T));
if (p_item.has_value()) {
p_item = std::nullopt;
} else {
p_stream->get<T>();
}
}
T front() const {
T val;
p_stream->read_bytes(&val, sizeof(T));
p_stream->seek(-sizeof(T), stream_seek::CUR);
return val;
if (p_item.has_value()) {
return p_item.value();
} else {
return (p_item = p_stream->get<T>()).value();
}
}
bool equals_front(stream_range const &s) const {
return p_stream->tell() == s.p_stream->tell();
return p_stream == s.p_stream;
}
void put(T val) {
p_stream->write_bytes(&val, sizeof(T));
p_size += sizeof(T);
p_stream->put(val);
}
private:
stream *p_stream;
stream_off_t p_size;
mutable std::optional<T> p_item;
};
template<typename T>