for (const char c : str) {

if (c == '\\' || c == '"' || c < 0x20) return true;

}

return false;

public:

JSONWriter(std::ostream& out, bool compact)

: out_(out), compact_(compact) {}

private:

inline void indent() { indent_ += 2; }

inline void deindent() { indent_ -= 2; }

inline void advance() {

if (compact_) return;

for (int i = 0; i < indent_; i++) out_ << ' ';

}

inline void write_one_space() {

if (compact_) return;

out_ << ' ';

}

inline void write_new_line() {

if (compact_) return;

out_ << '\n';

}

public:

inline void json_start() {

if (state_ == kAfterValue) out_ << ',';

write_new_line();

advance();

out_ << '{';

indent();

state_ = kObjectStart;

}

inline void json_end() {

write_new_line();

deindent();

advance();

out_ << '}';

state_ = kAfterValue;

}

template <typename T>

inline void json_objectstart(T key) {

if (state_ == kAfterValue) out_ << ',';

write_new_line();

advance();

write_string(key);

out_ << ':';

write_one_space();

out_ << '{';

indent();

state_ = kObjectStart;

}

template <typename T>

inline void json_arraystart(T key) {

if (state_ == kAfterValue) out_ << ',';

write_new_line();

advance();

write_string(key);

out_ << ':';

write_one_space();

out_ << '[';

indent();

state_ = kObjectStart;

}

inline void json_objectend() {

write_new_line();

deindent();

advance();

out_ << '}';

if (indent_ == 0) {

// Top-level object is complete, so end the line.

out_ << '\n';

}

state_ = kAfterValue;

}

inline void json_arrayend() {

write_new_line();

deindent();

advance();

out_ << ']';

state_ = kAfterValue;

}

template <typename T, typename U>

inline void json_keyvalue(const T& key, const U& value) {

if (state_ == kAfterValue) out_ << ',';

write_new_line();

advance();

write_string(key);

out_ << ':';

write_one_space();

write_value(value);

state_ = kAfterValue;

}

template <typename U>

inline void json_element(const U& value) {

if (state_ == kAfterValue) out_ << ',';

write_new_line();

advance();

write_value(value);

state_ = kAfterValue;

}

struct Null {}; // Usable as a JSON value.

struct ForeignJSON {

std::string as_string;

};

private:

template <typename T,

typename test_for_number = typename std::

enable_if<std::numeric_limits<T>::is_specialized, bool>::type>

inline void write_value(T number) {

if constexpr (std::is_same<T, bool>::value)

out_ << (number ? "true" : "false");

else

out_ << number;

}

inline void write_value(Null null) { out_ << "null"; }

inline void write_value(std::string_view str) { write_string(str); }

inline void write_value(const ForeignJSON& json) {

out_ << Reindent(json.as_string, indent_);

}

inline void write_string(std::string_view str) {

out_ << '"';

if (NeedsJsonEscape(str)) // only create temporary std::string if necessary

out_ << EscapeJsonChars(str);

else

out_ << str;

out_ << '"';

}

enum JSONState { kObjectStart, kAfterValue };

std::ostream& out_;

bool compact_;

int indent_ = 0;

int state_ = kObjectStart;