json::Node Class Reference

Public Types
enum class	Type {   number , string , array , object ,   boolean , null }

Public Member Functions
void	setOverrides (Node overrides)
Type	type () const
Node	optional (std::string const &key) const
Node	require (std::string const &key) const
Node	at (std::size_t index) const
std::size_t	size () const
double	asDouble () const
float	asFloat () const
int	asInt () const
std::string const &	asString () const
bool	asBool () const
	operator bool () const

Static Public Member Functions
static Node	readFrom (std::istream &)

Detailed Description

Definition at line 25 of file JsonParser.h.

Member Enumeration Documentation

Type

enum class json::Node::Type

strong

Definition at line 28 of file JsonParser.h.

        {
            number,
            string,
            array,
            object,
            boolean,
            null
        };

Member Function Documentation

asBool()

bool json::Node::asBool

(

)

const

Query the value of a boolean

Definition at line 322 of file JsonParser.cpp.

    {
        if (type() != Type::boolean) {
            throw std::runtime_error("JSON parser: Expected a boolean");
        }
        return dynamic_cast<Bool&>(*m_value).value;
    }

asDouble()

double json::Node::asDouble

(

)

const

Query the value of a number

Definition at line 290 of file JsonParser.cpp.

    {
        if (type() != Type::number) {
            throw std::runtime_error("JSON parser: Expected a number");
        }
        return dynamic_cast<Number&>(*m_value).value;
    }

asFloat()

float json::Node::asFloat

(

)

const

Query the value of a number

Definition at line 298 of file JsonParser.cpp.

    {
        return static_cast<float>(asDouble());
    }

asInt()

int json::Node::asInt

(

)

const

Query the value of a number and require it to be an integer

Definition at line 303 of file JsonParser.cpp.

    {
        auto value = asDouble();
        auto rounded = static_cast<int>(std::lround(value));
        auto error = value - rounded;
        if (error > 1e-6) {
            throw std::runtime_error("JSON parser: Expected an integer value");
        }
        return rounded;
    }

asString()

std::string const & json::Node::asString

(

)

const

Query the value of a string

Definition at line 314 of file JsonParser.cpp.

    {
        if (type() != Type::string) {
            throw std::runtime_error("JSON parser: Expected a string");
        }
        return dynamic_cast<String&>(*m_value).value;
    }

at()

Node json::Node::at

(

std::size_t

index

)

const

Query an array by index

Definition at line 269 of file JsonParser.cpp.

    {
        if (type() != Type::array) {
            throw std::runtime_error("JSON parser: Expected an array");
        }
        return{ dynamic_cast<Array&>(*m_value).value.at(index) };
    }

operator bool()

json::Node::operator bool

(

)

const

Anything apart from false and null is true

Definition at line 330 of file JsonParser.cpp.

    {
        switch (type()) {
            case Type::null:
                return false;
            case Type::boolean:
                return asBool();
            default:
                return true;
        }
    }

optional()

Node json::Node::optional

(

std::string const &

key

)

const

Query an object parameter, Null if not found

It is possible to specify overrides

Definition at line 238 of file JsonParser.cpp.

    {
        if (m_overrides) {
            try {
                return{ m_overrides->value.at(key) };
            }
            catch (std::out_of_range&) {}
        }
        try {
            return{ dynamic_cast<Object&>(*m_value).value.at(key) };
        }
        catch (std::out_of_range&) {
            return{ std::make_shared<Null>() };
        }
        catch (std::bad_cast&) {
            std::ostringstream what;
            what << "JSON parser: Querying optional key '" << key << "', but node is not an object";
            throw std::runtime_error(what.str());
        }
    }

readFrom()

Node json::Node::readFrom ( std::istream &  stream )

static

Read JSON from an input stream

Definition at line 203 of file JsonParser.cpp.

    {
        try {
            stream.exceptions(std::ios::badbit | std::ios::failbit);
            auto value = readValue(stream);
            skipWhitespace(stream);
 
            if (!stream.eof()) {
                auto ch = stream.get();
                std::ostringstream what;
                what << "Stray character " << static_cast<char>(ch) << " (0x" << std::ios::hex << ch << ")";
                throw std::runtime_error(what.str());
            }
 
            return{ value };
        }
        catch (std::runtime_error& e) {
            throw std::runtime_error(std::string("JSON parser: ") + e.what());
        }
        catch (std::exception& e) {
            throw std::logic_error(std::string("JSON parser bug: ") + e.what());
        }
    }

require()

Node json::Node::require

(

std::string const &

key

)

const

Query an object parameter, throws "parameter KEY is required" unless found

It is possible to specify overrides

Definition at line 259 of file JsonParser.cpp.

    {
        auto node = optional(key);
        if (node)
            return node;
        std::ostringstream stream;
        stream << "JSON parser: Parameter " << key << " is required but missing";
        throw std::runtime_error(stream.str());
    }

setOverrides()

void json::Node::setOverrides

(

Node

overrides

)

Definition at line 227 of file JsonParser.cpp.

    {
        assert(type() == Type::object && overrides.type() == Type::object);
        m_overrides = std::dynamic_pointer_cast<Object>(overrides.m_value);
    }

size()

std::size_t json::Node::size

(

)

const

Query the size of an array

Definition at line 277 of file JsonParser.cpp.

    {
        switch (type()) {
            case Type::array:
                return dynamic_cast<Array&>(*m_value).value.size();
            case Type::object:
                return dynamic_cast<Object&>(*m_value).value.size();
            default:
                throw std::runtime_error("JSON parser: Expected an array or object");
        }
 
    }

type()

Node::Type json::Node::type

(

)

const

Query the value type of this node

Definition at line 233 of file JsonParser.cpp.

    {
        return m_value->type;
    }

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The documentation for this class was generated from the following files:

• JsonParser.h
• JsonParser.cpp