qpdf/libqpdf/JSON.cc

#include <qpdf/JSON.hh>

#include <qpdf/QUtil.hh>
#include <qpdf/QTC.hh>
#include <stdexcept>
#include <cstring>

JSON::Members::~Members()
{
}

JSON::Members::Members(std::shared_ptr<JSON_value> value) :
    value(value)
{
}

JSON::JSON(std::shared_ptr<JSON_value> value) :
    m(new Members(value))
{
}

JSON::JSON_value::~JSON_value()
{
}

JSON::JSON_dictionary::~JSON_dictionary()
{
}

std::string JSON::JSON_dictionary::unparse(size_t depth) const
{
    std::string result = "{";
    bool first = true;
    for (auto const& iter: members)
    {
        if (first)
        {
            first = false;
        }
        else
        {
            result.append(1, ',');
        }
        result.append(1, '\n');
        result.append(2 * (1 + depth), ' ');
        result += ("\"" + iter.first + "\": " +
                   iter.second->unparse(1 + depth));
    }
    if (! first)
    {
        result.append(1, '\n');
        result.append(2 * depth, ' ');
    }
    result.append(1, '}');
    return result;
}

JSON::JSON_array::~JSON_array()
{
}

std::string JSON::JSON_array::unparse(size_t depth) const
{
    std::string result = "[";
    bool first = true;
    for (auto const& element: elements)
    {
        if (first)
        {
            first = false;
        }
        else
        {
            result.append(1, ',');
        }
        result.append(1, '\n');
        result.append(2 * (1 + depth), ' ');
        result += element->unparse(1 + depth);
    }
    if (! first)
    {
        result.append(1, '\n');
        result.append(2 * depth, ' ');
    }
    result.append(1, ']');
    return result;
}

JSON::JSON_string::JSON_string(std::string const& utf8) :
    utf8(utf8),
    encoded(encode_string(utf8))
{
}

JSON::JSON_string::~JSON_string()
{
}

std::string JSON::JSON_string::unparse(size_t) const
{
    return "\"" + encoded + "\"";
}

JSON::JSON_number::JSON_number(long long value) :
    encoded(QUtil::int_to_string(value))
{
}

JSON::JSON_number::JSON_number(double value) :
    encoded(QUtil::double_to_string(value, 6))
{
}

JSON::JSON_number::JSON_number(std::string const& value) :
    encoded(value)
{
}

JSON::JSON_number::~JSON_number()
{
}

std::string JSON::JSON_number::unparse(size_t) const
{
    return encoded;
}

JSON::JSON_bool::JSON_bool(bool val) :
    value(val)
{
}

JSON::JSON_bool::~JSON_bool()
{
}

std::string JSON::JSON_bool::unparse(size_t) const
{
    return value ? "true" : "false";
}

JSON::JSON_null::~JSON_null()
{
}

std::string JSON::JSON_null::unparse(size_t) const
{
    return "null";
}

std::string
JSON::unparse() const
{
    if (0 == this->m->value.get())
    {
        return "null";
    }
    else
    {
        return this->m->value->unparse(0);
    }
}

std::string
JSON::encode_string(std::string const& str)
{
    std::string result;
    size_t len = str.length();
    for (size_t i = 0; i < len; ++i)
    {
        unsigned char ch = static_cast<unsigned char>(str.at(i));
        switch (ch)
        {
          case '\\':
            result += "\\\\";
            break;
          case '\"':
            result += "\\\"";
            break;
          case '\b':
            result += "\\b";
            break;
          case '\f':
            result += "\\f";
            break;
          case '\n':
            result += "\\n";
            break;
          case '\r':
            result += "\\r";
            break;
          case '\t':
            result += "\\t";
            break;
          default:
            if (ch < 32)
            {
                result += "\\u" + QUtil::int_to_string_base(ch, 16, 4);
            }
            else
            {
                result.append(1, static_cast<char>(ch));
            }
        }
    }
    return result;
}

JSON
JSON::makeDictionary()
{
    return JSON(std::make_shared<JSON_dictionary>());
}

JSON
JSON::addDictionaryMember(std::string const& key, JSON const& val)
{
    JSON_dictionary* obj = dynamic_cast<JSON_dictionary*>(
        this->m->value.get());
    if (0 == obj)
    {
        throw std::runtime_error(
            "JSON::addDictionaryMember called on non-dictionary");
    }
    if (val.m->value.get())
    {
        obj->members[encode_string(key)] = val.m->value;
    }
    else
    {
        obj->members[encode_string(key)] = std::make_shared<JSON_null>();
    }
    return obj->members[encode_string(key)];
}

JSON
JSON::makeArray()
{
    return JSON(std::make_shared<JSON_array>());
}

JSON
JSON::addArrayElement(JSON const& val)
{
    JSON_array* arr = dynamic_cast<JSON_array*>(
        this->m->value.get());
    if (0 == arr)
    {
        throw std::runtime_error("JSON::addArrayElement called on non-array");
    }
    if (val.m->value.get())
    {
        arr->elements.push_back(val.m->value);
    }
    else
    {
        arr->elements.push_back(std::make_shared<JSON_null>());
    }
    return arr->elements.back();
}

JSON
JSON::makeString(std::string const& utf8)
{
    return JSON(std::make_shared<JSON_string>(utf8));
}

JSON
JSON::makeInt(long long int value)
{
    return JSON(std::make_shared<JSON_number>(value));
}

JSON
JSON::makeReal(double value)
{
    return JSON(std::make_shared<JSON_number>(value));
}

JSON
JSON::makeNumber(std::string const& encoded)
{
    return JSON(std::make_shared<JSON_number>(encoded));
}

JSON
JSON::makeBool(bool value)
{
    return JSON(std::make_shared<JSON_bool>(value));
}

JSON
JSON::makeNull()
{
    return JSON(std::make_shared<JSON_null>());
}

bool
JSON::isArray() const
{
    return nullptr != dynamic_cast<JSON_array const*>(
        this->m->value.get());
}

bool
JSON::isDictionary() const
{
    return nullptr != dynamic_cast<JSON_dictionary const*>(
        this->m->value.get());
}

bool
JSON::getString(std::string& utf8) const
{
    auto v = dynamic_cast<JSON_string const*>(this->m->value.get());
    if (v == nullptr)
    {
        return false;
    }
    utf8 = v->utf8;
    return true;
}

bool
JSON::getNumber(std::string& value) const
{
    auto v = dynamic_cast<JSON_number const*>(this->m->value.get());
    if (v == nullptr)
    {
        return false;
    }
    value = v->encoded;
    return true;
}

bool
JSON::getBool(bool& value) const
{
    auto v = dynamic_cast<JSON_bool const*>(this->m->value.get());
    if (v == nullptr)
    {
        return false;
    }
    value = v->value;
    return true;
}

bool
JSON::isNull() const
{
    if (dynamic_cast<JSON_null const*>(this->m->value.get()))
    {
        return true;
    }
    return false;
}

bool
JSON::forEachDictItem(
    std::function<void(std::string const& key, JSON value)> fn) const
{
    auto v = dynamic_cast<JSON_dictionary const*>(this->m->value.get());
    if (v == nullptr)
    {
        return false;
    }
    for (auto const& k: v->members)
    {
        fn(k.first, JSON(k.second));
    }
    return true;
}

bool
JSON::forEachArrayItem(std::function<void(JSON value)> fn) const
{
    auto v = dynamic_cast<JSON_array const*>(this->m->value.get());
    if (v == nullptr)
    {
        return false;
    }
    for (auto const& i: v->elements)
    {
        fn(JSON(i));
    }
    return true;
}

bool
JSON::checkSchema(JSON schema, std::list<std::string>& errors)
{
    return checkSchemaInternal(this->m->value.get(),
                               schema.m->value.get(),
                               0, errors, "");
}

bool
JSON::checkSchema(JSON schema, unsigned long flags,
                  std::list<std::string>& errors)
{
    return checkSchemaInternal(this->m->value.get(),
                               schema.m->value.get(),
                               flags, errors, "");
}

bool
JSON::checkSchemaInternal(JSON_value* this_v, JSON_value* sch_v,
                          unsigned long flags,
                          std::list<std::string>& errors,
                          std::string prefix)
{
    JSON_array* this_arr = dynamic_cast<JSON_array*>(this_v);
    JSON_dictionary* this_dict = dynamic_cast<JSON_dictionary*>(this_v);

    JSON_array* sch_arr = dynamic_cast<JSON_array*>(sch_v);
    JSON_dictionary* sch_dict = dynamic_cast<JSON_dictionary*>(sch_v);

    JSON_string* sch_str = dynamic_cast<JSON_string*>(sch_v);

    std::string err_prefix;
    if (prefix.empty())
    {
        err_prefix = "top-level object";
    }
    else
    {
        err_prefix = "json key \"" + prefix + "\"";
    }

    std::string pattern_key;
    if (sch_dict)
    {
        if (! this_dict)
        {
            QTC::TC("libtests", "JSON wanted dictionary");
            errors.push_back(err_prefix + " is supposed to be a dictionary");
            return false;
        }
        auto members = sch_dict->members;
        std::string key;
        if ((members.size() == 1) &&
            ((key = members.begin()->first, key.length() > 2) &&
             (key.at(0) == '<') &&
             (key.at(key.length() - 1) == '>')))
        {
            pattern_key = key;
        }
    }

    if (sch_dict && (! pattern_key.empty()))
    {
        auto pattern_schema = sch_dict->members[pattern_key].get();
        for (auto const& iter: this_dict->members)
        {
            std::string const& key = iter.first;
            checkSchemaInternal(
                this_dict->members[key].get(), pattern_schema,
                flags, errors, prefix + "." + key);
        }
    }
    else if (sch_dict)
    {
        for (auto& iter: sch_dict->members)
        {
            std::string const& key = iter.first;
            if (this_dict->members.count(key))
            {
                checkSchemaInternal(
                    this_dict->members[key].get(),
                    iter.second.get(),
                    flags, errors, prefix + "." + key);
            }
            else
            {
                if (flags & f_optional)
                {
                    QTC::TC("libtests", "JSON optional key");
                }
                else
                {
                    QTC::TC("libtests", "JSON key missing in object");
                    errors.push_back(
                        err_prefix + ": key \"" + key +
                        "\" is present in schema but missing in object");
                }
            }
        }
        for (auto const& iter: this_dict->members)
        {
            std::string const& key = iter.first;
            if (sch_dict->members.count(key) == 0)
            {
                QTC::TC("libtests", "JSON key extra in object");
                errors.push_back(
                    err_prefix + ": key \"" + key +
                    "\" is not present in schema but appears in object");
            }
        }
    }
    else if (sch_arr)
    {
        if (! this_arr)
        {
            QTC::TC("libtests", "JSON wanted array");
            errors.push_back(err_prefix + " is supposed to be an array");
            return false;
        }
        if (sch_arr->elements.size() != 1)
        {
            QTC::TC("libtests", "JSON schema array error");
            errors.push_back(err_prefix +
                             " schema array contains other than one item");
            return false;
        }
        int i = 0;
        for (auto const& element: this_arr->elements)
        {
            checkSchemaInternal(
                element.get(),
                sch_arr->elements.at(0).get(),
                flags, errors, prefix + "." + QUtil::int_to_string(i));
            ++i;
        }
    }
    else if (! sch_str)
    {
        QTC::TC("libtests", "JSON schema other type");
        errors.push_back(err_prefix +
                         " schema value is not dictionary, array, or string");
        return false;
    }

    return errors.empty();
}

namespace {
    class JSONParser
    {
      public:
        JSONParser() :
            lex_state(ls_top),
            number_before_point(0),
            number_after_point(0),
            number_after_e(0),
            number_saw_point(false),
            number_saw_e(false),
            cstr(nullptr),
            end(nullptr),
            tok_start(nullptr),
            tok_end(nullptr),
            p(nullptr),
            parser_state(ps_top)
        {
        }

        std::shared_ptr<JSON> parse(std::string const& s);

      private:
        void getToken();
        void handleToken();
        static std::string decode_string(std::string const& json);

        enum parser_state_e {
            ps_top,
            ps_dict_begin,
            ps_dict_after_key,
            ps_dict_after_colon,
            ps_dict_after_item,
            ps_dict_after_comma,
            ps_array_begin,
            ps_array_after_item,
            ps_array_after_comma,
            ps_done,
        };

        enum lex_state_e {
            ls_top,
            ls_number,
            ls_alpha,
            ls_string,
            ls_backslash,
        };

        lex_state_e lex_state;
        size_t number_before_point;
        size_t number_after_point;
        size_t number_after_e;
        bool number_saw_point;
        bool number_saw_e;
        char const* cstr;
        char const* end;
        char const* tok_start;
        char const* tok_end;
        char const* p;
        parser_state_e parser_state;
        std::vector<std::shared_ptr<JSON>> stack;
        std::vector<parser_state_e> ps_stack;
        std::string dict_key;
    };
}

std::string
JSONParser::decode_string(std::string const& str)
{
    // The string has already been validated when this private method
    // is called, so errors are logic errors instead of runtime
    // errors.
    size_t len = str.length();
    if ((len < 2) || (str.at(0) != '"') || (str.at(len-1) != '"'))
    {
        throw std::logic_error(
            "JSON Parse: decode_string called with other than \"...\"");
    }
    char const* s = str.c_str();
    // Move inside the quotation marks
    ++s;
    len -= 2;
    std::string result;
    for (size_t i = 0; i < len; ++i)
    {
        if (s[i] == '\\')
        {
            if (i + 1 >= len)
            {
                throw std::logic_error("JSON parse: nothing after \\");
            }
            char ch = s[++i];
            switch (ch)
            {
              case '\\':
              case '\"':
                result.append(1, ch);
                break;
              case 'b':
                result.append(1, '\b');
                break;
              case 'f':
                result.append(1, '\f');
                break;
              case 'n':
                result.append(1, '\n');
                break;
              case 'r':
                result.append(1, '\r');
                break;
              case 't':
                result.append(1, '\t');
                break;
              case 'u':
                if (i + 4 >= len)
                {
                    throw std::logic_error(
                        "JSON parse: not enough characters after \\u");
                }
                {
                    std::string hex =
                        QUtil::hex_decode(std::string(s+i+1, s+i+5));
                    i += 4;
                    unsigned char high = static_cast<unsigned char>(hex.at(0));
                    unsigned char low = static_cast<unsigned char>(hex.at(1));
                    unsigned long codepoint = high;
                    codepoint <<= 8;
                    codepoint += low;
                    result += QUtil::toUTF8(codepoint);
                }
                break;
              default:
                throw std::logic_error(
                    "JSON parse: bad character after \\");
                break;
            }
        }
        else
        {
            result.append(1, s[i]);
        }
    }
    return result;
}

void JSONParser::getToken()
{
    while (p < end)
    {
        if (*p == 0)
        {
            QTC::TC("libtests", "JSON parse null character");
            throw std::runtime_error(
                "JSON: null character at offset " +
                QUtil::int_to_string(p - cstr));
        }
        switch (lex_state)
        {
          case ls_top:
            if (*p == '"')
            {
                tok_start = p;
                tok_end = nullptr;
                lex_state = ls_string;
            }
            else if (QUtil::is_space(*p))
            {
                // ignore
            }
            else if ((*p >= 'a') && (*p <= 'z'))
            {
                tok_start = p;
                tok_end = nullptr;
                lex_state = ls_alpha;
            }
            else if (*p == '-')
            {
                tok_start = p;
                tok_end = nullptr;
                lex_state = ls_number;
                number_before_point = 0;
                number_after_point = 0;
                number_after_e = 0;
                number_saw_point = false;
                number_saw_e = false;
            }
            else if ((*p >= '0') && (*p <= '9'))
            {
                tok_start = p;
                tok_end = nullptr;
                lex_state = ls_number;
                number_before_point = 1;
                number_after_point = 0;
                number_after_e = 0;
                number_saw_point = false;
                number_saw_e = false;
            }
            else if (*p == '.')
            {
                tok_start = p;
                tok_end = nullptr;
                lex_state = ls_number;
                number_before_point = 0;
                number_after_point = 0;
                number_after_e = 0;
                number_saw_point = true;
                number_saw_e = false;
            }
            else if (strchr("{}[]:,", *p))
            {
                tok_start = p;
                tok_end = p + 1;
            }
            else
            {
                QTC::TC("libtests", "JSON parse bad character");
                throw std::runtime_error(
                    "JSON: offset " + QUtil::int_to_string(p - cstr) +
                    ": unexpected character " + std::string(p, 1));
            }
            break;

          case ls_number:
            if ((*p >= '0') && (*p <= '9'))
            {
                if (number_saw_e)
                {
                    ++number_after_e;
                }
                else if (number_saw_point)
                {
                    ++number_after_point;
                }
                else
                {
                    ++number_before_point;
                }
            }
            else if (*p == '.')
            {
                if (number_saw_e)
                {
                    QTC::TC("libtests", "JSON parse point after e");
                    throw std::runtime_error(
                        "JSON: offset " + QUtil::int_to_string(p - cstr) +
                        ": numeric literal: decimal point after e");
                }
                else if (number_saw_point)
                {
                    QTC::TC("libtests", "JSON parse duplicate point");
                    throw std::runtime_error(
                        "JSON: offset " + QUtil::int_to_string(p - cstr) +
                        ": numeric literal: decimal point already seen");
                }
                else
                {
                    number_saw_point = true;
                }
            }
            else if (*p == 'e')
            {
                if (number_saw_e)
                {
                    QTC::TC("libtests", "JSON parse duplicate e");
                    throw std::runtime_error(
                        "JSON: offset " + QUtil::int_to_string(p - cstr) +
                        ": numeric literal: e already seen");
                }
                else
                {
                    number_saw_e = true;
                }
            }
            else if ((*p == '+') || (*p == '-'))
            {
                if (number_saw_e && (number_after_e == 0))
                {
                    // okay
                }
                else
                {
                    QTC::TC("libtests", "JSON parse unexpected sign");
                    throw std::runtime_error(
                        "JSON: offset " + QUtil::int_to_string(p - cstr) +
                        ": numeric literal: unexpected sign");
                }
            }
            else if (QUtil::is_space(*p))
            {
                tok_end = p;
            }
            else if (strchr("{}[]:,", *p))
            {
                tok_end = p;
                --p;
            }
            else
            {
                QTC::TC("libtests", "JSON parse numeric bad character");
                throw std::runtime_error(
                    "JSON: offset " + QUtil::int_to_string(p - cstr) +
                    ": numeric literal: unexpected character " +
                    std::string(p, 1));
            }
            break;

          case ls_alpha:
            if ((*p >= 'a') && (*p <= 'z'))
            {
                // okay
            }
            else if (QUtil::is_space(*p))
            {
                tok_end = p;
            }
            else if (strchr("{}[]:,", *p))
            {
                tok_end = p;
                --p;
            }
            else
            {
                QTC::TC("libtests", "JSON parse keyword bad character");
                throw std::runtime_error(
                    "JSON: offset " + QUtil::int_to_string(p - cstr) +
                    ": keyword: unexpected character " + std::string(p, 1));
            }
            break;

          case ls_string:
            if (*p == '"')
            {
                tok_end = p + 1;
            }
            else if (*p == '\\')
            {
                lex_state = ls_backslash;
            }
            break;

          case ls_backslash:
            /* cSpell: ignore bfnrt */
            if (strchr("\\\"bfnrt", *p))
            {
                lex_state = ls_string;
            }
            else if (*p == 'u')
            {
                if (p + 4 >= end)
                {
                    QTC::TC("libtests", "JSON parse premature end of u");
                    throw std::runtime_error(
                        "JSON: offset " + QUtil::int_to_string(p - cstr) +
                        ": \\u must be followed by four characters");
                }
                for (size_t i = 1; i <= 4; ++i)
                {
                    if (! QUtil::is_hex_digit(p[i]))
                    {
                        QTC::TC("libtests", "JSON parse bad hex after u");
                        throw std::runtime_error(
                            "JSON: offset " + QUtil::int_to_string(p - cstr) +
                            ": \\u must be followed by four hex digits");
                    }
                }
                p += 4;
                lex_state = ls_string;
            }
            else
            {
                QTC::TC("libtests", "JSON parse backslash bad character");
                throw std::runtime_error(
                    "JSON: offset " + QUtil::int_to_string(p - cstr) +
                    ": invalid character after backslash: " +
                    std::string(p, 1));
            }
            break;
        }
        ++p;
        if (tok_start && tok_end)
        {
            break;
        }
    }
    if (p == end)
    {
        if (tok_start && (! tok_end))
        {
            switch (lex_state)
            {
              case ls_top:
                // Can't happen
                throw std::logic_error(
                    "tok_start set in ls_top while parsing " +
                    std::string(cstr));
                break;

              case ls_number:
              case ls_alpha:
                tok_end = p;
                break;

              case ls_string:
              case ls_backslash:
                QTC::TC("libtests", "JSON parse unterminated string");
                throw std::runtime_error(
                    "JSON: offset " + QUtil::int_to_string(p - cstr) +
                    ": unterminated string");
                break;
            }
        }
    }
}

void
JSONParser::handleToken()
{
    if (! (tok_start && tok_end))
    {
        return;
    }

    // Get token value.
    std::string value(tok_start, tok_end);

    if (parser_state == ps_done)
    {
        QTC::TC("libtests", "JSON parse junk after object");
        throw std::runtime_error(
            "JSON: offset " + QUtil::int_to_string(p - cstr) +
            ": material follows end of object: " + value);
    }

    // Git string value
    std::string s_value;
    if (lex_state == ls_string)
    {
        // Token includes the quotation marks
        if (tok_end - tok_start < 2)
        {
            throw std::logic_error("JSON string length < 2");
        }
        s_value = decode_string(value);
    }
    // Based on the lexical state and value, figure out whether we are
    // looking at an item or a delimiter. It will always be exactly
    // one of those two or an error condition.

    std::shared_ptr<JSON> item;
    char delimiter = '\0';
    switch (lex_state)
    {
      case ls_top:
        switch (*tok_start)
        {
          case '{':
            item = std::make_shared<JSON>(JSON::makeDictionary());
            break;

          case '[':
            item = std::make_shared<JSON>(JSON::makeArray());
            break;

          default:
            delimiter = *tok_start;
            break;
        }
        break;

      case ls_number:
        if (number_saw_point && (number_after_point == 0))
        {
            QTC::TC("libtests", "JSON parse decimal with no digits");
            throw std::runtime_error(
                "JSON: offset " + QUtil::int_to_string(p - cstr) +
                ": decimal point with no digits");
        }
        if ((number_before_point > 1) &&
            ((tok_start[0] == '0') ||
             ((tok_start[0] == '-') && (tok_start[1] == '0'))))
        {
            QTC::TC("libtests", "JSON parse leading zero");
            throw std::runtime_error(
                "JSON: offset " + QUtil::int_to_string(p - cstr) +
                ": number with leading zero");
        }
        if ((number_before_point == 0) && (number_after_point == 0))
        {
            QTC::TC("libtests", "JSON parse number no digits");
            throw std::runtime_error(
                "JSON: offset " + QUtil::int_to_string(p - cstr) +
                ": number with no digits");
        }
        item = std::make_shared<JSON>(JSON::makeNumber(value));
        break;

      case ls_alpha:
        if (value == "true")
        {
            item = std::make_shared<JSON>(JSON::makeBool(true));
        }
        else if (value == "false")
        {
            item = std::make_shared<JSON>(JSON::makeBool(false));
        }
        else if (value == "null")
        {
            item = std::make_shared<JSON>(JSON::makeNull());
        }
        else
        {
            QTC::TC("libtests", "JSON parse invalid keyword");
            throw std::runtime_error(
                "JSON: offset " + QUtil::int_to_string(p - cstr) +
                ": invalid keyword " + value);
        }
        break;

      case ls_string:
        item = std::make_shared<JSON>(JSON::makeString(s_value));
        break;

      case ls_backslash:
        throw std::logic_error(
            "tok_end is set while state = ls_backslash");
        break;
    }

    if ((item.get() == nullptr) == (delimiter == '\0'))
    {
        throw std::logic_error(
            "JSONParser::handleToken: logic error: exactly one of item"
            " or delimiter must be set");
    }

    // See whether what we have is allowed at this point.

    if (item.get())
    {
        switch (parser_state)
        {
          case ps_done:
            throw std::logic_error("can't happen; ps_done already handled");
            break;

          case ps_dict_after_key:
            QTC::TC("libtests", "JSON parse expected colon");
            throw std::runtime_error(
                "JSON: offset " + QUtil::int_to_string(p - cstr) +
                ": expected ':'");
            break;

          case ps_dict_after_item:
            QTC::TC("libtests", "JSON parse expected , or }");
            throw std::runtime_error(
                "JSON: offset " + QUtil::int_to_string(p - cstr) +
                ": expected ',' or '}'");
            break;

          case ps_array_after_item:
            QTC::TC("libtests", "JSON parse expected, or ]");
            throw std::runtime_error(
                "JSON: offset " + QUtil::int_to_string(p - cstr) +
                ": expected ',' or ']'");
            break;

          case ps_dict_begin:
          case ps_dict_after_comma:
            if (lex_state != ls_string)
            {
                QTC::TC("libtests", "JSON parse string as dict key");
                throw std::runtime_error(
                    "JSON: offset " + QUtil::int_to_string(p - cstr) +
                    ": expect string as dictionary key");
            }
            break;

          case ps_top:
          case ps_dict_after_colon:
          case ps_array_begin:
          case ps_array_after_comma:
            break;
            // okay
        }
    }
    else if (delimiter == '}')
    {
        if (! ((parser_state == ps_dict_begin) ||
               (parser_state == ps_dict_after_item)))

        {
            QTC::TC("libtests", "JSON parse unexpected }");
            throw std::runtime_error(
                "JSON: offset " + QUtil::int_to_string(p - cstr) +
                ": unexpected dictionary end delimiter");
        }
    }
    else if (delimiter == ']')
    {
        if (! ((parser_state == ps_array_begin) ||
               (parser_state == ps_array_after_item)))

        {
            QTC::TC("libtests", "JSON parse unexpected ]");
            throw std::runtime_error(
                "JSON: offset " + QUtil::int_to_string(p - cstr) +
                ": unexpected array end delimiter");
        }
    }
    else if (delimiter == ':')
    {
        if (parser_state != ps_dict_after_key)
        {
            QTC::TC("libtests", "JSON parse unexpected :");
            throw std::runtime_error(
                "JSON: offset " + QUtil::int_to_string(p - cstr) +
                ": unexpected colon");
        }
    }
    else if (delimiter == ',')
    {
        if (! ((parser_state == ps_dict_after_item) ||
               (parser_state == ps_array_after_item)))
        {
            QTC::TC("libtests", "JSON parse unexpected ,");
            throw std::runtime_error(
                "JSON: offset " + QUtil::int_to_string(p - cstr) +
                ": unexpected comma");
        }
    }
    else if (delimiter != '\0')
    {
        throw std::logic_error("JSONParser::handleToken: bad delimiter");
    }

    // Now we know we have a delimiter or item that is allowed. Do
    // whatever we need to do with it.

    parser_state_e next_state = ps_top;
    if (delimiter == ':')
    {
        next_state = ps_dict_after_colon;
    }
    else if (delimiter == ',')
    {
        if (parser_state == ps_dict_after_item)
        {
            next_state = ps_dict_after_comma;
        }
        else if (parser_state == ps_array_after_item)
        {
            next_state = ps_array_after_comma;
        }
        else
        {
            throw std::logic_error(
                "JSONParser::handleToken: unexpected parser"
                " state for comma");
        }
    }
    else if ((delimiter == '}') || (delimiter == ']'))
    {
        next_state = ps_stack.back();
        ps_stack.pop_back();
        if (next_state != ps_done)
        {
            stack.pop_back();
        }
    }
    else if (delimiter != '\0')
    {
        throw std::logic_error(
            "JSONParser::handleToken: unexpected delimiter in transition");
    }
    else if (item.get())
    {
        std::shared_ptr<JSON> tos;
        if (! stack.empty())
        {
            tos = stack.back();
        }
        switch (parser_state)
        {
          case ps_dict_begin:
          case ps_dict_after_comma:
            this->dict_key = s_value;
            item = nullptr;
            next_state = ps_dict_after_key;
            break;

          case ps_dict_after_colon:
            tos->addDictionaryMember(dict_key, *item);
            next_state = ps_dict_after_item;
            break;

          case ps_array_begin:
          case ps_array_after_comma:
            next_state = ps_array_after_item;
            tos->addArrayElement(*item);
            break;

          case ps_top:
            next_state = ps_done;
            break;

          case ps_dict_after_key:
          case ps_dict_after_item:
          case ps_array_after_item:
          case ps_done:
            throw std::logic_error(
                "JSONParser::handleToken: unexpected parser state");
        }
    }
    else
    {
        throw std::logic_error(
            "JSONParser::handleToken: unexpected null item in transition");
    }

    // Prepare for next token
    if (item.get())
    {
        if (item->isDictionary())
        {
            stack.push_back(item);
            ps_stack.push_back(next_state);
            next_state = ps_dict_begin;
        }
        else if (item->isArray())
        {
            stack.push_back(item);
            ps_stack.push_back(next_state);
            next_state = ps_array_begin;
        }
        else if (parser_state == ps_top)
        {
            stack.push_back(item);
        }
    }
    parser_state = next_state;
    tok_start = nullptr;
    tok_end = nullptr;
    lex_state = ls_top;
}

std::shared_ptr<JSON>
JSONParser::parse(std::string const& s)
{
    cstr = s.c_str();
    end = cstr + s.length();
    p = cstr;

    while (p < end)
    {
        getToken();
        handleToken();
    }
    if (parser_state != ps_done)
    {
        QTC::TC("libtests", "JSON parse premature EOF");
        throw std::runtime_error("JSON: premature end of input");
    }
    return stack.back();
}

JSON
JSON::parse(std::string const& s)
{
    JSONParser jp;
    return *jp.parse(s);
}