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libtgvoip/json11.cpp

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/* Copyright (c) 2013 Dropbox, Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "json11.hpp"
#include <cassert>
#include <cmath>
#include <cstdlib>
#include <cstdio>
#include <limits>
#include <sstream>
#include <locale>
namespace json11 {
static const int max_depth = 200;
using std::string;
using std::vector;
using std::map;
using std::make_shared;
using std::initializer_list;
using std::move;
/* Helper for representing null - just a do-nothing struct, plus comparison
* operators so the helpers in JsonValue work. We can't use nullptr_t because
* it may not be orderable.
*/
struct NullStruct {
bool operator==(NullStruct) const { return true; }
bool operator<(NullStruct) const { return false; }
};
/* * * * * * * * * * * * * * * * * * * *
* Serialization
*/
static void dump(NullStruct, string &out) {
out += "null";
}
static void dump(double value, string &out) {
if (std::isfinite(value)) {
char buf[32];
snprintf(buf, sizeof buf, "%.17g", value);
out += buf;
} else {
out += "null";
}
}
static void dump(int value, string &out) {
char buf[32];
snprintf(buf, sizeof buf, "%d", value);
out += buf;
}
static void dump(bool value, string &out) {
out += value ? "true" : "false";
}
static void dump(const string &value, string &out) {
out += '"';
for (size_t i = 0; i < value.length(); i++) {
const char ch = value[i];
if (ch == '\\') {
out += "\\\\";
} else if (ch == '"') {
out += "\\\"";
} else if (ch == '\b') {
out += "\\b";
} else if (ch == '\f') {
out += "\\f";
} else if (ch == '\n') {
out += "\\n";
} else if (ch == '\r') {
out += "\\r";
} else if (ch == '\t') {
out += "\\t";
} else if (static_cast<uint8_t>(ch) <= 0x1f) {
char buf[8];
snprintf(buf, sizeof buf, "\\u%04x", ch);
out += buf;
} else if (static_cast<uint8_t>(ch) == 0xe2 && static_cast<uint8_t>(value[i+1]) == 0x80
&& static_cast<uint8_t>(value[i+2]) == 0xa8) {
out += "\\u2028";
i += 2;
} else if (static_cast<uint8_t>(ch) == 0xe2 && static_cast<uint8_t>(value[i+1]) == 0x80
&& static_cast<uint8_t>(value[i+2]) == 0xa9) {
out += "\\u2029";
i += 2;
} else {
out += ch;
}
}
out += '"';
}
static void dump(const Json::array &values, string &out) {
bool first = true;
out += "[";
for (const auto &value : values) {
if (!first)
out += ", ";
value.dump(out);
first = false;
}
out += "]";
}
static void dump(const Json::object &values, string &out) {
bool first = true;
out += "{";
for (const auto &kv : values) {
if (!first)
out += ", ";
dump(kv.first, out);
out += ": ";
kv.second.dump(out);
first = false;
}
out += "}";
}
void Json::dump(string &out) const {
m_ptr->dump(out);
}
/* * * * * * * * * * * * * * * * * * * *
* Value wrappers
*/
template <Json::Type tag, typename T>
class Value : public JsonValue {
protected:
// Constructors
explicit Value(const T &value) : m_value(value) {}
explicit Value(T &&value) : m_value(move(value)) {}
// Get type tag
Json::Type type() const override {
return tag;
}
// Comparisons
bool equals(const JsonValue * other) const override {
return m_value == static_cast<const Value<tag, T> *>(other)->m_value;
}
bool less(const JsonValue * other) const override {
return m_value < static_cast<const Value<tag, T> *>(other)->m_value;
}
const T m_value;
void dump(string &out) const override { json11::dump(m_value, out); }
};
class JsonDouble final : public Value<Json::NUMBER, double> {
double number_value() const override { return m_value; }
int int_value() const override { return static_cast<int>(m_value); }
bool equals(const JsonValue * other) const override { return m_value == other->number_value(); }
bool less(const JsonValue * other) const override { return m_value < other->number_value(); }
public:
explicit JsonDouble(double value) : Value(value) {}
};
class JsonInt final : public Value<Json::NUMBER, int> {
double number_value() const override { return m_value; }
int int_value() const override { return m_value; }
bool equals(const JsonValue * other) const override { return m_value == other->number_value(); }
bool less(const JsonValue * other) const override { return m_value < other->number_value(); }
public:
explicit JsonInt(int value) : Value(value) {}
};
class JsonBoolean final : public Value<Json::BOOL, bool> {
bool bool_value() const override { return m_value; }
public:
explicit JsonBoolean(bool value) : Value(value) {}
};
class JsonString final : public Value<Json::STRING, string> {
const string &string_value() const override { return m_value; }
public:
explicit JsonString(const string &value) : Value(value) {}
explicit JsonString(string &&value) : Value(move(value)) {}
};
class JsonArray final : public Value<Json::ARRAY, Json::array> {
const Json::array &array_items() const override { return m_value; }
const Json & operator[](size_t i) const override;
public:
explicit JsonArray(const Json::array &value) : Value(value) {}
explicit JsonArray(Json::array &&value) : Value(move(value)) {}
};
class JsonObject final : public Value<Json::OBJECT, Json::object> {
const Json::object &object_items() const override { return m_value; }
const Json & operator[](const string &key) const override;
public:
explicit JsonObject(const Json::object &value) : Value(value) {}
explicit JsonObject(Json::object &&value) : Value(move(value)) {}
};
class JsonNull final : public Value<Json::NUL, NullStruct> {
public:
JsonNull() : Value({}) {}
};
/* * * * * * * * * * * * * * * * * * * *
* Static globals - static-init-safe
*/
struct Statics {
const std::shared_ptr<JsonValue> null = make_shared<JsonNull>();
const std::shared_ptr<JsonValue> t = make_shared<JsonBoolean>(true);
const std::shared_ptr<JsonValue> f = make_shared<JsonBoolean>(false);
const string empty_string;
const vector<Json> empty_vector;
const map<string, Json> empty_map;
Statics() {}
};
static const Statics & statics() {
static const Statics s {};
return s;
}
static const Json & static_null() {
// This has to be separate, not in Statics, because Json() accesses statics().null.
static const Json json_null;
return json_null;
}
/* * * * * * * * * * * * * * * * * * * *
* Constructors
*/
Json::Json() noexcept : m_ptr(statics().null) {}
Json::Json(std::nullptr_t) noexcept : m_ptr(statics().null) {}
Json::Json(double value) : m_ptr(make_shared<JsonDouble>(value)) {}
Json::Json(int value) : m_ptr(make_shared<JsonInt>(value)) {}
Json::Json(bool value) : m_ptr(value ? statics().t : statics().f) {}
Json::Json(const string &value) : m_ptr(make_shared<JsonString>(value)) {}
Json::Json(string &&value) : m_ptr(make_shared<JsonString>(move(value))) {}
Json::Json(const char * value) : m_ptr(make_shared<JsonString>(value)) {}
Json::Json(const Json::array &values) : m_ptr(make_shared<JsonArray>(values)) {}
Json::Json(Json::array &&values) : m_ptr(make_shared<JsonArray>(move(values))) {}
Json::Json(const Json::object &values) : m_ptr(make_shared<JsonObject>(values)) {}
Json::Json(Json::object &&values) : m_ptr(make_shared<JsonObject>(move(values))) {}
/* * * * * * * * * * * * * * * * * * * *
* Accessors
*/
Json::Type Json::type() const { return m_ptr->type(); }
double Json::number_value() const { return m_ptr->number_value(); }
int Json::int_value() const { return m_ptr->int_value(); }
bool Json::bool_value() const { return m_ptr->bool_value(); }
const string & Json::string_value() const { return m_ptr->string_value(); }
const vector<Json> & Json::array_items() const { return m_ptr->array_items(); }
const map<string, Json> & Json::object_items() const { return m_ptr->object_items(); }
const Json & Json::operator[] (size_t i) const { return (*m_ptr)[i]; }
const Json & Json::operator[] (const string &key) const { return (*m_ptr)[key]; }
double JsonValue::number_value() const { return 0; }
int JsonValue::int_value() const { return 0; }
bool JsonValue::bool_value() const { return false; }
const string & JsonValue::string_value() const { return statics().empty_string; }
const vector<Json> & JsonValue::array_items() const { return statics().empty_vector; }
const map<string, Json> & JsonValue::object_items() const { return statics().empty_map; }
const Json & JsonValue::operator[] (size_t) const { return static_null(); }
const Json & JsonValue::operator[] (const string &) const { return static_null(); }
const Json & JsonObject::operator[] (const string &key) const {
auto iter = m_value.find(key);
return (iter == m_value.end()) ? static_null() : iter->second;
}
const Json & JsonArray::operator[] (size_t i) const {
if (i >= m_value.size()) return static_null();
else return m_value[i];
}
/* * * * * * * * * * * * * * * * * * * *
* Comparison
*/
bool Json::operator== (const Json &other) const {
if (m_ptr == other.m_ptr)
return true;
if (m_ptr->type() != other.m_ptr->type())
return false;
return m_ptr->equals(other.m_ptr.get());
}
bool Json::operator< (const Json &other) const {
if (m_ptr == other.m_ptr)
return false;
if (m_ptr->type() != other.m_ptr->type())
return m_ptr->type() < other.m_ptr->type();
return m_ptr->less(other.m_ptr.get());
}
/* * * * * * * * * * * * * * * * * * * *
* Parsing
*/
/* esc(c)
*
* Format char c suitable for printing in an error message.
*/
static inline string esc(char c) {
char buf[12];
if (static_cast<uint8_t>(c) >= 0x20 && static_cast<uint8_t>(c) <= 0x7f) {
snprintf(buf, sizeof buf, "'%c' (%d)", c, c);
} else {
snprintf(buf, sizeof buf, "(%d)", c);
}
return string(buf);
}
static inline bool in_range(long x, long lower, long upper) {
return (x >= lower && x <= upper);
}
namespace {
/* JsonParser
*
* Object that tracks all state of an in-progress parse.
*/
struct JsonParser final {
/* State
*/
const string &str;
size_t i;
string &err;
bool failed;
const JsonParse strategy;
/* fail(msg, err_ret = Json())
*
* Mark this parse as failed.
*/
Json fail(string &&msg) {
return fail(move(msg), Json());
}
template <typename T>
T fail(string &&msg, const T err_ret) {
if (!failed)
err = std::move(msg);
failed = true;
return err_ret;
}
/* consume_whitespace()
*
* Advance until the current character is non-whitespace.
*/
void consume_whitespace() {
while (str[i] == ' ' || str[i] == '\r' || str[i] == '\n' || str[i] == '\t')
i++;
}
/* consume_comment()
*
* Advance comments (c-style inline and multiline).
*/
bool consume_comment() {
bool comment_found = false;
if (str[i] == '/') {
i++;
if (i == str.size())
return fail("unexpected end of input after start of comment", false);
if (str[i] == '/') { // inline comment
i++;
// advance until next line, or end of input
while (i < str.size() && str[i] != '\n') {
i++;
}
comment_found = true;
}
else if (str[i] == '*') { // multiline comment
i++;
if (i > str.size()-2)
return fail("unexpected end of input inside multi-line comment", false);
// advance until closing tokens
while (!(str[i] == '*' && str[i+1] == '/')) {
i++;
if (i > str.size()-2)
return fail(
"unexpected end of input inside multi-line comment", false);
}
i += 2;
comment_found = true;
}
else
return fail("malformed comment", false);
}
return comment_found;
}
/* consume_garbage()
*
* Advance until the current character is non-whitespace and non-comment.
*/
void consume_garbage() {
consume_whitespace();
if(strategy == JsonParse::COMMENTS) {
bool comment_found = false;
do {
comment_found = consume_comment();
if (failed) return;
consume_whitespace();
}
while(comment_found);
}
}
/* get_next_token()
*
* Return the next non-whitespace character. If the end of the input is reached,
* flag an error and return 0.
*/
char get_next_token() {
consume_garbage();
if (failed) return (char)0;
if (i == str.size())
return fail("unexpected end of input", (char)0);
return str[i++];
}
/* encode_utf8(pt, out)
*
* Encode pt as UTF-8 and add it to out.
*/
void encode_utf8(long pt, string & out) {
if (pt < 0)
return;
if (pt < 0x80) {
out += static_cast<char>(pt);
} else if (pt < 0x800) {
out += static_cast<char>((pt >> 6) | 0xC0);
out += static_cast<char>((pt & 0x3F) | 0x80);
} else if (pt < 0x10000) {
out += static_cast<char>((pt >> 12) | 0xE0);
out += static_cast<char>(((pt >> 6) & 0x3F) | 0x80);
out += static_cast<char>((pt & 0x3F) | 0x80);
} else {
out += static_cast<char>((pt >> 18) | 0xF0);
out += static_cast<char>(((pt >> 12) & 0x3F) | 0x80);
out += static_cast<char>(((pt >> 6) & 0x3F) | 0x80);
out += static_cast<char>((pt & 0x3F) | 0x80);
}
}
/* parse_string()
*
* Parse a string, starting at the current position.
*/
string parse_string() {
string out;
long last_escaped_codepoint = -1;
while (true) {
if (i == str.size())
return fail("unexpected end of input in string", "");
char ch = str[i++];
if (ch == '"') {
encode_utf8(last_escaped_codepoint, out);
return out;
}
if (in_range(ch, 0, 0x1f))
return fail("unescaped " + esc(ch) + " in string", "");
// The usual case: non-escaped characters
if (ch != '\\') {
encode_utf8(last_escaped_codepoint, out);
last_escaped_codepoint = -1;
out += ch;
continue;
}
// Handle escapes
if (i == str.size())
return fail("unexpected end of input in string", "");
ch = str[i++];
if (ch == 'u') {
// Extract 4-byte escape sequence
string esc = str.substr(i, 4);
// Explicitly check length of the substring. The following loop
// relies on std::string returning the terminating NUL when
// accessing str[length]. Checking here reduces brittleness.
if (esc.length() < 4) {
return fail("bad \\u escape: " + esc, "");
}
for (size_t j = 0; j < 4; j++) {
if (!in_range(esc[j], 'a', 'f') && !in_range(esc[j], 'A', 'F')
&& !in_range(esc[j], '0', '9'))
return fail("bad \\u escape: " + esc, "");
}
long codepoint = strtol(esc.data(), nullptr, 16);
// JSON specifies that characters outside the BMP shall be encoded as a pair
// of 4-hex-digit \u escapes encoding their surrogate pair components. Check
// whether we're in the middle of such a beast: the previous codepoint was an
// escaped lead (high) surrogate, and this is a trail (low) surrogate.
if (in_range(last_escaped_codepoint, 0xD800, 0xDBFF)
&& in_range(codepoint, 0xDC00, 0xDFFF)) {
// Reassemble the two surrogate pairs into one astral-plane character, per
// the UTF-16 algorithm.
encode_utf8((((last_escaped_codepoint - 0xD800) << 10)
| (codepoint - 0xDC00)) + 0x10000, out);
last_escaped_codepoint = -1;
} else {
encode_utf8(last_escaped_codepoint, out);
last_escaped_codepoint = codepoint;
}
i += 4;
continue;
}
encode_utf8(last_escaped_codepoint, out);
last_escaped_codepoint = -1;
if (ch == 'b') {
out += '\b';
} else if (ch == 'f') {
out += '\f';
} else if (ch == 'n') {
out += '\n';
} else if (ch == 'r') {
out += '\r';
} else if (ch == 't') {
out += '\t';
} else if (ch == '"' || ch == '\\' || ch == '/') {
out += ch;
} else {
return fail("invalid escape character " + esc(ch), "");
}
}
}
/* parse_number()
*
* Parse a double.
*/
Json parse_number() {
size_t start_pos = i;
if (str[i] == '-')
i++;
// Integer part
if (str[i] == '0') {
i++;
if (in_range(str[i], '0', '9'))
return fail("leading 0s not permitted in numbers");
} else if (in_range(str[i], '1', '9')) {
i++;
while (in_range(str[i], '0', '9'))
i++;
} else {
return fail("invalid " + esc(str[i]) + " in number");
}
if (str[i] != '.' && str[i] != 'e' && str[i] != 'E'
&& (i - start_pos) <= static_cast<size_t>(std::numeric_limits<int>::digits10)) {
return std::atoi(str.c_str() + start_pos);
}
// Decimal part
if (str[i] == '.') {
i++;
if (!in_range(str[i], '0', '9'))
return fail("at least one digit required in fractional part");
while (in_range(str[i], '0', '9'))
i++;
}
// Exponent part
if (str[i] == 'e' || str[i] == 'E') {
i++;
if (str[i] == '+' || str[i] == '-')
i++;
if (!in_range(str[i], '0', '9'))
return fail("at least one digit required in exponent");
while (in_range(str[i], '0', '9'))
i++;
}
std::istringstream stm(std::string(str.begin()+start_pos, str.end()));
stm.imbue(std::locale("C"));
double result;
stm >> result;
return result;
}
/* expect(str, res)
*
* Expect that 'str' starts at the character that was just read. If it does, advance
* the input and return res. If not, flag an error.
*/
Json expect(const string &expected, Json res) {
assert(i != 0);
i--;
if (str.compare(i, expected.length(), expected) == 0) {
i += expected.length();
return res;
} else {
return fail("parse error: expected " + expected + ", got " + str.substr(i, expected.length()));
}
}
/* parse_json()
*
* Parse a JSON object.
*/
Json parse_json(int depth) {
if (depth > max_depth) {
return fail("exceeded maximum nesting depth");
}
char ch = get_next_token();
if (failed)
return Json();
if (ch == '-' || (ch >= '0' && ch <= '9')) {
i--;
return parse_number();
}
if (ch == 't')
return expect("true", true);
if (ch == 'f')
return expect("false", false);
if (ch == 'n')
return expect("null", Json());
if (ch == '"')
return parse_string();
if (ch == '{') {
map<string, Json> data;
ch = get_next_token();
if (ch == '}')
return data;
while (1) {
if (ch != '"')
return fail("expected '\"' in object, got " + esc(ch));
string key = parse_string();
if (failed)
return Json();
ch = get_next_token();
if (ch != ':')
return fail("expected ':' in object, got " + esc(ch));
data[std::move(key)] = parse_json(depth + 1);
if (failed)
return Json();
ch = get_next_token();
if (ch == '}')
break;
if (ch != ',')
return fail("expected ',' in object, got " + esc(ch));
ch = get_next_token();
}
return data;
}
if (ch == '[') {
vector<Json> data;
ch = get_next_token();
if (ch == ']')
return data;
while (1) {
i--;
data.push_back(parse_json(depth + 1));
if (failed)
return Json();
ch = get_next_token();
if (ch == ']')
break;
if (ch != ',')
return fail("expected ',' in list, got " + esc(ch));
ch = get_next_token();
(void)ch;
}
return data;
}
return fail("expected value, got " + esc(ch));
}
};
}//namespace {
Json Json::parse(const string &in, string &err, JsonParse strategy) {
JsonParser parser { in, 0, err, false, strategy };
Json result = parser.parse_json(0);
// Check for any trailing garbage
parser.consume_garbage();
if (parser.failed)
return Json();
if (parser.i != in.size())
return parser.fail("unexpected trailing " + esc(in[parser.i]));
return result;
}
// Documented in json11.hpp
vector<Json> Json::parse_multi(const string &in,
std::string::size_type &parser_stop_pos,
string &err,
JsonParse strategy) {
JsonParser parser { in, 0, err, false, strategy };
parser_stop_pos = 0;
vector<Json> json_vec;
while (parser.i != in.size() && !parser.failed) {
json_vec.push_back(parser.parse_json(0));
if (parser.failed)
break;
// Check for another object
parser.consume_garbage();
if (parser.failed)
break;
parser_stop_pos = parser.i;
}
return json_vec;
}
/* * * * * * * * * * * * * * * * * * * *
* Shape-checking
*/
bool Json::has_shape(const shape & types, string & err) const {
if (!is_object()) {
err = "expected JSON object, got " + dump();
return false;
}
for (auto & item : types) {
if ((*this)[item.first].type() != item.second) {
err = "bad type for " + item.first + " in " + dump();
return false;
}
}
return true;
}
} // namespace json11
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