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#include "json.hh"
#include <cassert>
#include <charconv>
#include <cstddef>
#include <cstdint>
#include <memory>
#include <ostream>
#include <string>
#include <string_view>
#include <system_error>
#include <vector>
namespace json {
namespace {
struct StackEntry {
enum class Type : uint8_t {
kRoot,
kObject,
kArray,
};
Type type;
bool need_comma{false};
explicit StackEntry(Type type) : type(type) {}
};
class BaseWriter : public Writer {
public:
BaseWriter() : stack_({StackEntry(StackEntry::Type::kRoot)}) {}
void value(std::string_view value) override {
before_value();
quote(value);
}
void value(int64_t value) override {
before_value();
write(value);
}
void value(uint64_t value) override {
before_value();
write(value);
}
void value(float value) override {
before_value();
write(value);
}
void value(double value) override {
before_value();
write(value);
}
void value(bool value) override {
before_value();
write(value);
}
void value(std::nullptr_t) override {
before_value();
write(nullptr);
}
void start_array() override {
before_value();
stack_.emplace_back(StackEntry::Type::kArray);
write('[');
}
void end_array() override {
if (stack_.empty()) {
assert(false);
return;
}
assert(stack_.back().type == StackEntry::Type::kArray);
stack_.pop_back();
write(']');
if (!stack_.empty())
stack_.back().need_comma = true;
}
void start_object() override {
before_value();
stack_.emplace_back(StackEntry::Type::kObject);
write('{');
}
void key(std::string_view name) override {
if (stack_.empty()) {
assert(false);
return;
}
assert(stack_.back().type == StackEntry::Type::kObject);
if (stack_.back().need_comma) {
write(',');
stack_.back().need_comma = false;
}
quote(name);
write(':');
}
void end_object() override {
if (stack_.empty()) {
assert(false);
return;
}
assert(stack_.back().type == StackEntry::Type::kObject);
stack_.pop_back();
write('}');
if (!stack_.empty())
stack_.back().need_comma = true;
}
void clear() override {
stack_.clear();
stack_.emplace_back(StackEntry::Type::kRoot);
}
protected:
virtual void write(int64_t value) = 0;
virtual void write(uint64_t value) = 0;
virtual void write(float value) = 0;
virtual void write(double value) = 0;
virtual void write(bool value) = 0;
virtual void write(char value) = 0;
virtual void write(std::string_view value) = 0;
virtual void write(std::nullptr_t) = 0;
void write(char const* value) { this->write(std::string_view(value)); }
private:
void before_value() {
if (stack_.empty()) {
assert(false);
return;
}
if (stack_.back().need_comma) {
assert(stack_.back().type != StackEntry::Type::kRoot);
write(',');
} else {
stack_.back().need_comma = true;
}
}
void quote(std::string_view str) {
write('"');
size_t last = 0;
while (true) {
auto pos = need_quote(str, last);
if (pos == std::string_view::npos) {
write(str.substr(last));
break;
}
write(str.substr(last, pos - last));
switch (str[pos]) {
case '"':
write("\\\"");
break;
case '\\':
write("\\\\");
break;
case '\n':
write("\\n");
break;
case '\r':
write("\\r");
break;
case '\t':
write("\\t");
break;
case '\b':
write("\\b");
break;
case '\f':
write("\\f");
break;
default: {
char tmp[4];
write("\\u");
auto [ptr, ec] = std::to_chars(tmp, tmp + sizeof(tmp), str[pos], 16);
if (ec == std::errc()) {
size_t len = ptr - tmp;
assert(len > 0);
for (size_t i = 4; i > len; --i)
write('0');
write(std::string_view(tmp, len));
} else {
assert(false);
}
break;
};
}
last = pos + 1;
}
write('"');
}
static inline size_t need_quote(std::string_view str, size_t offset) {
for (; offset < str.size(); ++offset) {
if (str[offset] == '\\' || str[offset] == '"' ||
(str[offset] >= 0 && str[offset] < ' '))
return offset;
}
return std::string_view::npos;
}
std::vector<StackEntry> stack_;
};
class IosWriter : public BaseWriter {
public:
explicit IosWriter(std::ostream& out) : out_(out) {}
void write(std::string_view value) override { out_ << value; }
void write(int64_t value) override { out_ << value; }
void write(uint64_t value) override { out_ << value; }
void write(float value) override { out_ << value; }
void write(double value) override { out_ << value; }
void write(bool value) override { out_ << (value ? "true" : "false"); }
void write(char value) override { out_ << value; }
void write(std::nullptr_t) override { out_ << "null"; }
private:
std::ostream& out_;
};
class StringWriter : public BaseWriter {
public:
explicit StringWriter(std::string& out) : out_(out) {}
void write(std::string_view value) override { out_.append(value); }
void write(int64_t value) override {
auto [ptr, ec] = std::to_chars(tmp_, tmp_ + sizeof(tmp_), value);
if (ec == std::errc()) {
out_.append(tmp_, ptr - tmp_);
} else {
assert(false);
}
}
void write(uint64_t value) override {
auto [ptr, ec] = std::to_chars(tmp_, tmp_ + sizeof(tmp_), value);
if (ec == std::errc()) {
out_.append(tmp_, ptr - tmp_);
} else {
assert(false);
}
}
void write(float value) override {
auto [ptr, ec] = std::to_chars(tmp_, tmp_ + sizeof(tmp_), value);
if (ec == std::errc()) {
out_.append(tmp_, ptr - tmp_);
} else {
assert(false);
}
}
void write(double value) override {
auto [ptr, ec] = std::to_chars(tmp_, tmp_ + sizeof(tmp_), value);
if (ec == std::errc()) {
out_.append(tmp_, ptr - tmp_);
} else {
assert(false);
}
}
void write(bool value) override { out_.append(value ? "true" : "false"); }
void write(char value) override { out_.push_back(value); }
void write(std::nullptr_t) override { out_.append("null"); }
void clear() override {
BaseWriter::clear();
out_.clear();
}
private:
std::string& out_;
char tmp_[100];
};
} // namespace
void Writer::value(char const* value) { this->value(std::string_view(value)); }
void Writer::value(int32_t value) { this->value(static_cast<int64_t>(value)); }
void Writer::value(uint32_t value) {
this->value(static_cast<uint64_t>(value));
}
std::unique_ptr<Writer> writer(std::string& out) {
return std::make_unique<StringWriter>(out);
}
std::unique_ptr<Writer> writer(std::ostream& out) {
return std::make_unique<IosWriter>(out);
}
} // namespace json
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