⚡ micro-optimizations for dump()
Indentation string is recycled to avoid allocations. Comma-separation in objects does not need an if any more. Cachegrind measures 1% performance improvement.
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2 changed files with 34 additions and 28 deletions
31
src/json.hpp
31
src/json.hpp
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@ -8430,34 +8430,36 @@ class basic_json
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// variable to hold indentation for recursive calls
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const auto new_indent = current_indent + indent_step;
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const std::string indent_string = string_t(new_indent, ' ');
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string_t indent_string = string_t(new_indent, ' ');
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for (auto i = m_value.object->cbegin(); i != m_value.object->cend(); ++i)
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auto i = m_value.object->cbegin();
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for (size_t cnt = 0; cnt < m_value.object->size() - 1; ++cnt, ++i)
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{
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if (i != m_value.object->cbegin())
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{
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o << ",\n";
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}
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o << indent_string << '\"' << escape_string(i->first) << "\": ";
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i->second.dump(o, true, indent_step, new_indent);
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o << ",\n";
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}
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o << '\n' << string_t(current_indent, ' ') + '}';
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o << indent_string << '\"' << escape_string(i->first) << "\": ";
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i->second.dump(o, true, indent_step, new_indent);
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indent_string.resize(current_indent);
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o << '\n' << indent_string << '}';
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}
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else
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{
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o << '{';
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for (auto i = m_value.object->cbegin(); i != m_value.object->cend(); ++i)
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auto i = m_value.object->cbegin();
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for (size_t cnt = 0; cnt < m_value.object->size() - 1; ++cnt, ++i)
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{
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if (i != m_value.object->cbegin())
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{
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o << ',';
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}
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o << '\"' << escape_string(i->first) << "\":";
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i->second.dump(o, false, indent_step, current_indent);
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o << ',';
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}
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o << '\"' << escape_string(i->first) << "\":";
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i->second.dump(o, false, indent_step, current_indent);
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o << '}';
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}
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@ -8478,7 +8480,7 @@ class basic_json
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// variable to hold indentation for recursive calls
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const auto new_indent = current_indent + indent_step;
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const std::string indent_string = string_t(new_indent, ' ');
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string_t indent_string = string_t(new_indent, ' ');
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for (auto i = m_value.array->cbegin(); i != m_value.array->cend() - 1; ++i)
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{
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@ -8491,7 +8493,8 @@ class basic_json
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assert(not m_value.array->empty());
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m_value.array->back().dump(o, true, indent_step, new_indent);
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o << '\n' << string_t(current_indent, ' ') << ']';
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indent_string.resize(current_indent);
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o << '\n' << indent_string << ']';
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}
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else
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{
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@ -8430,34 +8430,36 @@ class basic_json
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// variable to hold indentation for recursive calls
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const auto new_indent = current_indent + indent_step;
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const std::string indent_string = string_t(new_indent, ' ');
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string_t indent_string = string_t(new_indent, ' ');
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for (auto i = m_value.object->cbegin(); i != m_value.object->cend(); ++i)
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auto i = m_value.object->cbegin();
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for (size_t cnt = 0; cnt < m_value.object->size() - 1; ++cnt, ++i)
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{
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if (i != m_value.object->cbegin())
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{
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o << ",\n";
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}
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o << indent_string << '\"' << escape_string(i->first) << "\": ";
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i->second.dump(o, true, indent_step, new_indent);
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o << ",\n";
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}
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o << '\n' << string_t(current_indent, ' ') + '}';
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o << indent_string << '\"' << escape_string(i->first) << "\": ";
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i->second.dump(o, true, indent_step, new_indent);
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indent_string.resize(current_indent);
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o << '\n' << indent_string << '}';
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}
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else
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{
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o << '{';
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for (auto i = m_value.object->cbegin(); i != m_value.object->cend(); ++i)
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auto i = m_value.object->cbegin();
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for (size_t cnt = 0; cnt < m_value.object->size() - 1; ++cnt, ++i)
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{
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if (i != m_value.object->cbegin())
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{
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o << ',';
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}
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o << '\"' << escape_string(i->first) << "\":";
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i->second.dump(o, false, indent_step, current_indent);
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o << ',';
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}
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o << '\"' << escape_string(i->first) << "\":";
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i->second.dump(o, false, indent_step, current_indent);
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o << '}';
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}
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@ -8478,7 +8480,7 @@ class basic_json
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// variable to hold indentation for recursive calls
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const auto new_indent = current_indent + indent_step;
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const std::string indent_string = string_t(new_indent, ' ');
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string_t indent_string = string_t(new_indent, ' ');
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for (auto i = m_value.array->cbegin(); i != m_value.array->cend() - 1; ++i)
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{
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@ -8491,7 +8493,8 @@ class basic_json
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assert(not m_value.array->empty());
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m_value.array->back().dump(o, true, indent_step, new_indent);
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o << '\n' << string_t(current_indent, ' ') << ']';
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indent_string.resize(current_indent);
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o << '\n' << indent_string << ']';
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}
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else
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{
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