⚡ micro-optimizations for dump()
All ‘<<‘ calls have been replaced by write()/put() calls. The indentation strings needs not to be resized. Cachegrind measures 1% performance improvement.
This commit is contained in:
Niels Lohmann
parent
b1441f3485
commit
0f04e42dd5
2 changed files with 132 additions and 52 deletions
92
src/json.hpp
92
src/json.hpp
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@ -8420,47 +8420,69 @@ class basic_json
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{
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if (m_value.object->empty())
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{
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o << "{}";
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o.write("{}", 2);
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return;
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}
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if (pretty_print)
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{
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o << "{\n";
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o.write("{\n", 2);
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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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string_t indent_string = string_t(new_indent, ' ');
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// first n-1 elements
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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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o << indent_string << '\"' << escape_string(i->first) << "\": ";
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o.write(indent_string.c_str(), new_indent);
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o.put('\"');
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const auto s = escape_string(i->first);
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o.write(s.c_str(), static_cast<std::streamsize>(s.size()));
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o.write("\": ", 3);
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i->second.dump(o, true, indent_step, new_indent);
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o << ",\n";
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o.write(",\n", 2);
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}
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o << indent_string << '\"' << escape_string(i->first) << "\": ";
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// last element
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assert(i != m_value.object->cend());
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o.write(indent_string.c_str(), new_indent);
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o.put('\"');
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const auto s = escape_string(i->first);
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o.write(s.c_str(), static_cast<std::streamsize>(s.size()));
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o.write("\": ", 3);
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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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o.put('\n');
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o.write(indent_string.c_str(), current_indent);
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o.put('}');
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}
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else
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{
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o << '{';
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o.put('{');
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// first n-1 elements
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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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o << '\"' << escape_string(i->first) << "\":";
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o.put('\"');
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const auto s = escape_string(i->first);
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o.write(s.c_str(), static_cast<std::streamsize>(s.size()));
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o.write("\":", 2);
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i->second.dump(o, false, indent_step, current_indent);
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o << ',';
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o.put(',');
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}
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o << '\"' << escape_string(i->first) << "\":";
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// last element
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assert(i != m_value.object->cend());
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o.put('\"');
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const auto s = escape_string(i->first);
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o.write(s.c_str(), static_cast<std::streamsize>(s.size()));
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o.write("\":", 2);
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i->second.dump(o, false, indent_step, current_indent);
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o << '}';
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o.put('}');
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}
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return;
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@ -8470,43 +8492,51 @@ class basic_json
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{
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if (m_value.array->empty())
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{
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o << "[]";
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o.write("[]", 2);
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return;
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}
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if (pretty_print)
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{
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o << "[\n";
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o.write("[\n", 2);
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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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string_t indent_string = string_t(new_indent, ' ');
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// first n-1 elements
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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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o << indent_string;
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o.write(indent_string.c_str(), new_indent);
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i->dump(o, true, indent_step, new_indent);
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o << ",\n";
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o.write(",\n", 2);
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}
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o << indent_string;
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// last element
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assert(not m_value.array->empty());
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o.write(indent_string.c_str(), new_indent);
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m_value.array->back().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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o.put('\n');
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o.write(indent_string.c_str(), current_indent);
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o.put(']');
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}
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else
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{
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o << '[';
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o.put('[');
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// first n-1 elements
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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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i->dump(o, false, indent_step, current_indent);
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o << ',';
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o.put(',');
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}
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// last element
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assert(not m_value.array->empty());
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m_value.array->back().dump(o, false, indent_step, current_indent);
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o << ']';
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o.put(']');
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}
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return;
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@ -8514,13 +8544,23 @@ class basic_json
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case value_t::string:
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{
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o << '\"' << escape_string(*m_value.string) << '\"';
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o.put('\"');
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const auto s = escape_string(*m_value.string);
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o.write(s.c_str(), static_cast<std::streamsize>(s.size()));
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o.put('\"');
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return;
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}
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case value_t::boolean:
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{
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o << (m_value.boolean ? "true" : "false");
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if (m_value.boolean)
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{
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o.write("true", 4);
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}
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else
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{
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o.write("false", 5);
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}
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return;
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}
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@ -8544,13 +8584,13 @@ class basic_json
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case value_t::discarded:
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{
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o << "<discarded>";
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o.write("<discarded>", 11);
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return;
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}
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case value_t::null:
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{
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o << "null";
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o.write("null", 4);
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return;
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}
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}
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@ -8420,47 +8420,69 @@ class basic_json
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{
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if (m_value.object->empty())
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{
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o << "{}";
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o.write("{}", 2);
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return;
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}
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if (pretty_print)
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{
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o << "{\n";
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o.write("{\n", 2);
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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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string_t indent_string = string_t(new_indent, ' ');
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// first n-1 elements
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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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o << indent_string << '\"' << escape_string(i->first) << "\": ";
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o.write(indent_string.c_str(), new_indent);
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o.put('\"');
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const auto s = escape_string(i->first);
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o.write(s.c_str(), static_cast<std::streamsize>(s.size()));
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o.write("\": ", 3);
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i->second.dump(o, true, indent_step, new_indent);
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o << ",\n";
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o.write(",\n", 2);
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}
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o << indent_string << '\"' << escape_string(i->first) << "\": ";
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// last element
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assert(i != m_value.object->cend());
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o.write(indent_string.c_str(), new_indent);
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o.put('\"');
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const auto s = escape_string(i->first);
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o.write(s.c_str(), static_cast<std::streamsize>(s.size()));
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o.write("\": ", 3);
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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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o.put('\n');
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o.write(indent_string.c_str(), current_indent);
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o.put('}');
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}
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else
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{
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o << '{';
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o.put('{');
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// first n-1 elements
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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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o << '\"' << escape_string(i->first) << "\":";
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o.put('\"');
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const auto s = escape_string(i->first);
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o.write(s.c_str(), static_cast<std::streamsize>(s.size()));
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o.write("\":", 2);
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i->second.dump(o, false, indent_step, current_indent);
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o << ',';
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o.put(',');
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}
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o << '\"' << escape_string(i->first) << "\":";
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// last element
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assert(i != m_value.object->cend());
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o.put('\"');
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const auto s = escape_string(i->first);
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o.write(s.c_str(), static_cast<std::streamsize>(s.size()));
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o.write("\":", 2);
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i->second.dump(o, false, indent_step, current_indent);
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o << '}';
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o.put('}');
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}
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return;
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@ -8470,43 +8492,51 @@ class basic_json
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{
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if (m_value.array->empty())
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{
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o << "[]";
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o.write("[]", 2);
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return;
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}
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if (pretty_print)
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{
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o << "[\n";
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o.write("[\n", 2);
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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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string_t indent_string = string_t(new_indent, ' ');
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// first n-1 elements
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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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o << indent_string;
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o.write(indent_string.c_str(), new_indent);
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i->dump(o, true, indent_step, new_indent);
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o << ",\n";
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o.write(",\n", 2);
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}
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o << indent_string;
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// last element
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assert(not m_value.array->empty());
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o.write(indent_string.c_str(), new_indent);
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m_value.array->back().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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o.put('\n');
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o.write(indent_string.c_str(), current_indent);
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o.put(']');
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}
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else
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{
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o << '[';
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o.put('[');
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// first n-1 elements
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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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i->dump(o, false, indent_step, current_indent);
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o << ',';
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o.put(',');
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}
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// last element
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assert(not m_value.array->empty());
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m_value.array->back().dump(o, false, indent_step, current_indent);
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o << ']';
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o.put(']');
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}
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return;
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@ -8514,13 +8544,23 @@ class basic_json
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case value_t::string:
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{
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o << '\"' << escape_string(*m_value.string) << '\"';
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o.put('\"');
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const auto s = escape_string(*m_value.string);
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o.write(s.c_str(), static_cast<std::streamsize>(s.size()));
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o.put('\"');
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return;
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}
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case value_t::boolean:
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{
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o << (m_value.boolean ? "true" : "false");
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if (m_value.boolean)
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{
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o.write("true", 4);
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}
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else
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{
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o.write("false", 5);
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}
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return;
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}
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@ -8544,13 +8584,13 @@ class basic_json
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case value_t::discarded:
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{
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o << "<discarded>";
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o.write("<discarded>", 11);
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return;
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}
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case value_t::null:
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{
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o << "null";
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o.write("null", 4);
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return;
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}
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}
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