NDL file¶

NDL - is a custom interface definition language, that based on WebIDL format.

Kotlin and C code generates based on this file when Gradle is synchronized in IDEA.

namespace global {
    void simpleFunc();
    boolean myFunc(MyDictionary params, Array<int> flags, MyCallback response);
    [Dealloc] string returnString();
    [Critical] void fastFunc();
}

enum MyEnum {
    "CASE1",
    "CASE2"
};

callback MyCallback = boolean (int arg);

dictionary ParentDictionary {
    MyEnum a;
    int b;
};

dictionary MyDictionary: ParentDictionary {
    int c;
    int d;
};

Types mapping¶

Many types are currently supported, but there are still limitations.

NDL	Kotlin	C	Kotlin Array	C Array
int	Int	KInt	IntArray	KIntArray
long	Long	KLong	LongArray	KLongArray
float	Float	KFloat	FloatArray	KFloatArray
double	Double	KDouble	DoubleArray	KDoubleArray
char	Char	KChar	CharArray	KCharArray
boolean	Boolean	KBoolean	BooleanArray	KBooleanArray
byte	Byte	KByte	ByteArray	KByteArray
short	Short	KShort	ShortArray	KShortArray
string	String	KString
void	Unit	void
Callback	Callback	Callback	Array<Callback>	Array<Callback>
Struct	Struct	Struct	Array<Struct>	Array<Struct>

Functions¶

Functions are used to call code. They have the following format:

type name(argType arg, ...);

To declare a callable function, place it inside namespace global block.

Example:

namespace global {
    int pow2(int num);
}

Dictionary¶

A Dictionary is a data container.

All its fields are copied when passed between Native and Kotlin.

Example:

dictionary UserInfo {
    string name;
    string lastName;
    int age;
}

namespace global {
    void sendUserInfo(UserInfo info);
}

Callback¶

Callback is used to call Kotlin from Native.

Example:

callback OnResponse = void (int response);

namespace global {
    void request(OnResponse result);
}

Enums¶

Enums are some typed constants.

Example:

enum MyEnum {
    "CASE1",
    "CASE2"
};

Annotations¶

There are several annotations that affect the generated code.

• Dealloc (read more in Memory model)
• Critical (read more in Critical)

Annotations can be placed before functions or their arguments.

Example:

namespace global {
    [Dealloc] Array<int> returnInts();
    [Critical] void sendFast();
}