JSON_writer.hh
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#ifndef JSON_WRITER_HH
#define JSON_WRITER_HH
#include <qpdf/JSON.hh>
#include <qpdf/Pipeline.hh>
#include <qpdf/Pl_Base64.hh>
#include <qpdf/Pl_Concatenate.hh>
#include <string_view>
// Writer is a small utility class to aid writing JSON to a pipeline. Methods are designed to allow
// chaining of calls.
//
// Some uses of the class have a significant performance impact. The class is intended purely for
// internal use to allow it to be adapted as needed to maintain performance.
class JSON::Writer
{
public:
Writer(Pipeline* p, size_t depth) :
p(p),
indent(2 * depth)
{
}
Writer&
write(char const* data, size_t len)
{
p->write(reinterpret_cast<unsigned char const*>(data), len);
return *this;
}
Writer&
writeBase64(std::string_view sv)
{
auto encoded = Pl_Base64::encode(sv);
p->write(reinterpret_cast<unsigned char const*>(encoded.data()), encoded.size());
return *this;
}
Writer&
writeNext()
{
auto n = indent;
if (first) {
first = false;
write(&spaces[1], n % n_spaces + 1);
} else {
write(&spaces[0], n % n_spaces + 2);
}
while (n >= n_spaces) {
write(&spaces[2], n_spaces);
n -= n_spaces;
}
return *this;
}
Writer&
writeStart(char const& c)
{
write(&c, 1);
first = true;
indent += 2;
return *this;
}
Writer&
writeEnd(char const& c)
{
if (indent > 1) {
indent -= 2;
}
if (!first) {
first = true;
writeNext();
}
first = false;
write(&c, 1);
return *this;
}
Writer&
operator<<(std::string_view sv)
{
p->write(reinterpret_cast<unsigned char const*>(sv.data()), sv.size());
return *this;
}
Writer&
operator<<(char const* s)
{
*this << std::string_view{s};
return *this;
}
Writer&
operator<<(bool val)
{
*this << (val ? "true" : "false");
return *this;
}
Writer&
operator<<(int val)
{
*this << std::to_string(val);
return *this;
}
Writer&
operator<<(size_t val)
{
*this << std::to_string(val);
return *this;
}
Writer&
operator<<(JSON&& j)
{
j.write(p, indent / 2);
return *this;
}
static std::string encode_string(std::string const& utf8);
private:
Pipeline* p;
bool first{true};
size_t indent;
static constexpr std::string_view spaces =
",\n ";
static constexpr auto n_spaces = spaces.size() - 2;
};
#endif // JSON_WRITER_HH