58 lines
1.7 KiB
C++
58 lines
1.7 KiB
C++
#pragma once
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#include <istream>
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template <typename C, int delimiterCount, int blockSize = 0x1000 / sizeof(C)> // windows file block size
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class BlockMarkupIterator
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{
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public:
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BlockMarkupIterator(const std::istream& stream, const std::basic_string_view<C>(&delimiters)[delimiterCount]) : streambuf(*stream.rdbuf())
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{
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std::copy_n(delimiters, delimiterCount, this->delimiters.begin());
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}
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std::optional<std::array<std::basic_string<C>, delimiterCount>> Next()
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{
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std::array<std::basic_string<C>, delimiterCount> results;
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Find(delimiters[0], true);
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for (int i = 0; i < delimiterCount; ++i)
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{
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const auto delimiter = i + 1 < delimiterCount ? delimiters[i + 1] : end;
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if (auto found = Find(delimiter, false)) results[i] = std::move(found.value());
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else return {};
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}
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return results;
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}
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private:
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std::optional<std::basic_string<C>> Find(std::basic_string_view<C> delimiter, bool discard)
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{
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for (int i = 0; ;)
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{
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int pos = buffer.find(delimiter, i);
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if (pos != std::string::npos)
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{
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auto result = !discard ? std::optional(std::basic_string(buffer.begin(), buffer.begin() + pos)) : std::nullopt;
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buffer.erase(buffer.begin(), buffer.begin() + pos + delimiter.size());
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return result;
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}
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int oldSize = buffer.size();
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buffer.resize(oldSize + blockSize);
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if (!streambuf.sgetn((char*)(buffer.data() + oldSize), blockSize * sizeof(C))) return {};
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i = max(0, oldSize - (int)delimiter.size());
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if (discard)
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{
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buffer.erase(0, i);
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i = 0;
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}
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}
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}
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static constexpr C endImpl[5] = { '|', 'E', 'N', 'D', '|' };
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static constexpr std::basic_string_view end{ endImpl, 5 };
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std::basic_streambuf<char>& streambuf;
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std::basic_string<C> buffer;
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std::array<std::basic_string_view<C>, delimiterCount> delimiters;
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};
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