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https://github.com/nlohmann/json.git
synced 2025-07-09 11:01:47 +03:00
improved performance for dump()
This commit is contained in:
Niels
122
src/json.hpp
122
src/json.hpp
@ -779,14 +779,18 @@ class basic_json
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*/
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inline string_t dump(const int indent = -1) const noexcept
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{
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std::stringstream ss;
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if (indent >= 0)
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{
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return dump(true, static_cast<unsigned int>(indent));
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dump(ss, true, static_cast<unsigned int>(indent));
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}
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else
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{
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return dump(false, 0);
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dump(ss, false, 0);
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}
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return ss.str();
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}
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/// return the type of the object (explicit)
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@ -1964,19 +1968,21 @@ class basic_json
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friend std::ostream& operator<<(std::ostream& o, const basic_json& j)
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{
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// read width member and use it as indentation parameter if nonzero
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const int indentation = (o.width() == 0) ? -1 : o.width();
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const bool prettyPrint = (o.width() > 0);
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const auto indentation = (prettyPrint ? o.width() : 0);
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o << j.dump(indentation);
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// reset width to 0 for subsequent calls to this stream
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o.width(0);
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// do the actual serialization
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j.dump(o, prettyPrint, indentation);
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return o;
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}
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/// serialize to stream
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friend std::ostream& operator>>(const basic_json& j, std::ostream& o)
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{
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// read width member and use it as indentation parameter if nonzero
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const int indentation = (o.width() == 0) ? -1 : o.width();
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o << j.dump(indentation);
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o << j;
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return o;
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}
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@ -2067,15 +2073,11 @@ class basic_json
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characters by a sequence of "\u" followed by a four-digit hex
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representation.
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@param o the stream to write the escaped string to
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@param s the string to escape
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@return escaped string
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*/
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static string_t escape_string(const string_t& s) noexcept
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static void escape_string(std::ostream& o, const string_t& s) noexcept
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{
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// create a result string of at least the size than s
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string_t result;
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result.reserve(s.size());
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for (const auto c : s)
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{
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switch (c)
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@ -2083,49 +2085,49 @@ class basic_json
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// quotation mark (0x22)
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case '"':
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{
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result += "\\\"";
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o << "\\\"";
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break;
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}
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// reverse solidus (0x5c)
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case '\\':
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{
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result += "\\\\";
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o << "\\\\";
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break;
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}
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// backspace (0x08)
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case '\b':
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{
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result += "\\b";
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o << "\\b";
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break;
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}
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// formfeed (0x0c)
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case '\f':
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{
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result += "\\f";
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o << "\\f";
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break;
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}
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// newline (0x0a)
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case '\n':
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{
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result += "\\n";
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o << "\\n";
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break;
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}
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// carriage return (0x0d)
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case '\r':
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{
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result += "\\r";
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o << "\\r";
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break;
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}
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// horizontal tab (0x09)
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case '\t':
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{
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result += "\\t";
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o << "\\t";
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break;
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}
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@ -2135,24 +2137,19 @@ class basic_json
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{
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// control characters (everything between 0x00 and 0x1f)
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// -> create four-digit hex representation
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std::basic_stringstream<typename string_t::value_type> ss;
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ss << "\\u" << std::hex << std::setw(4) << std::setfill('0') << int(c);
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result += ss.str();
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o << "\\u" << std::hex << std::setw(4) << std::setfill('0') << int(c);
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}
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else
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{
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// all other characters are added as-is
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result.append(1, c);
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o << c;
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}
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break;
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}
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}
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}
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return result;
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}
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/*!
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@brief internal implementation of the serialization function
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@ -2166,108 +2163,115 @@ class basic_json
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std::to_string()
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- floating-point numbers are converted to a string using "%g" format
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@param o stream to write to
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@param prettyPrint whether the output shall be pretty-printed
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@param indentStep the indent level
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@param currentIndent the current indent level (only used internally)
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*/
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inline string_t dump(const bool prettyPrint, const unsigned int indentStep,
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const unsigned int currentIndent = 0) const noexcept
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inline void dump(std::ostream& o, const bool prettyPrint, const unsigned int indentStep,
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const unsigned int currentIndent = 0) const noexcept
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{
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// variable to hold indentation for recursive calls
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auto new_indent = currentIndent;
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// helper function to return whitespace as indentation
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const auto indent = [prettyPrint, &new_indent]()
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{
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return prettyPrint ? string_t(new_indent, ' ') : string_t();
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};
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switch (m_type)
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{
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case (value_t::object):
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{
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if (m_value.object->empty())
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{
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return "{}";
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o << "{}";
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return;
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}
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string_t result = "{";
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o << "{";
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// increase indentation
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if (prettyPrint)
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{
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new_indent += indentStep;
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result += "\n";
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o << "\n";
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}
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for (auto i = m_value.object->cbegin(); i != m_value.object->cend(); ++i)
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{
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if (i != m_value.object->cbegin())
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{
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result += prettyPrint ? ",\n" : ",";
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o << (prettyPrint ? ",\n" : ",");
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}
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result += indent() + "\"" + escape_string(i->first) + "\":" + (prettyPrint ? " " : "")
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+ i->second.dump(prettyPrint, indentStep, new_indent);
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o << string_t(new_indent, ' ') << "\"";
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escape_string(o, i->first);
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o << "\":" << (prettyPrint ? " " : "");
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i->second.dump(o, prettyPrint, indentStep, new_indent);
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}
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// decrease indentation
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if (prettyPrint)
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{
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new_indent -= indentStep;
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result += "\n";
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o << "\n";
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}
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return result + indent() + "}";
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o << string_t(new_indent, ' ') + "}";
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return;
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}
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case (value_t::array):
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{
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if (m_value.array->empty())
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{
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return "[]";
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o << "[]";
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return;
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}
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string_t result = "[";
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o << "[";
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// increase indentation
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if (prettyPrint)
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{
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new_indent += indentStep;
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result += "\n";
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o << "\n";
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}
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for (auto i = m_value.array->cbegin(); i != m_value.array->cend(); ++i)
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{
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if (i != m_value.array->cbegin())
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{
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result += prettyPrint ? ",\n" : ",";
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o << (prettyPrint ? ",\n" : ",");
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}
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result += indent() + i->dump(prettyPrint, indentStep, new_indent);
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o << string_t(new_indent, ' ');
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i->dump(o, prettyPrint, indentStep, new_indent);
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}
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// decrease indentation
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if (prettyPrint)
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{
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new_indent -= indentStep;
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result += "\n";
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o << "\n";
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}
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return result + indent() + "]";
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o << string_t(new_indent, ' ') << "]";
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return;
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}
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case (value_t::string):
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{
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return string_t("\"") + escape_string(*m_value.string) + "\"";
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o << string_t("\"");
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escape_string(o, *m_value.string);
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o << "\"";
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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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return m_value.boolean ? "true" : "false";
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o << (m_value.boolean ? "true" : "false");
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return;
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}
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case (value_t::number_integer):
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{
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return std::to_string(m_value.number_integer);
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o << m_value.number_integer;
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return;
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}
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case (value_t::number_float):
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@ -2277,16 +2281,20 @@ class basic_json
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const auto sz = static_cast<unsigned int>(std::snprintf(nullptr, 0, "%.15g", m_value.number_float));
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std::vector<typename string_t::value_type> buf(sz + 1);
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std::snprintf(&buf[0], buf.size(), "%.15g", m_value.number_float);
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return string_t(buf.data());
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o << buf.data();
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return;
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}
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case (value_t::discarded):
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{
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return "<discarded>";
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o << "<discarded>";
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return;
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}
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default:
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{
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return "null";
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o << "null";
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return;
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}
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}
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}
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