Godobuf v0.2.2

About

Godobuf is a Google Protocol buffers compiler from .proto-file description to GDScript output file. Output file contains user protobuf messages represented by classes and protobuf core code which responsible for data serialization/deserialization. Godobuf used as plugin for Godot v3.x
Godobuf is easy to use, does not require rebuilding the Godot, because it is written in GDScript. All you need is to start the plugin.

Features

Supported

• Protobuf v2 and v3
• Message definitions (cascade messages)
• Simple Protobuf types (int32, uint32, sint32, fixed32, sfixed32
  int64, uint64, sint64, fixed64, sfixed64, float, double, bool, enum, string, bytes)
• Oneof type
• Map type
• Repeated fields
• Option packed for fields
• Protobuf imports (also public modificator)
• Debug string for class (message) fields (since v0.2.1)

Not supported

• Packages
• Reserved statements
• Services
• Any types
• Default values option for fields

Installation

1. Create a new project in Godot or use an existing project.
2. Copy addons directory from Godobuf repository to your Gotot project directory.
3. Choose in Menu Project->Project Settings.
   
   
4. In Project Settings window choose Plugins tab.
5. Find Godobuf plugin and set status Active.
   
   
6. Close Project Settings window.
7. The Godobuf panel will be displayed in the Godot
   

Usage

1. Open file dialog window Input protobuf file.
2. Choose *.proto file in a dialog window.
   
   
3. Open file dialog window Output GDScript file.
4. Choose directory and enter output file name.
   
   
5. Press Compile button.
6. See Godot Output for details.
7. All possilble errors details are displayed in Godot Output
8. After task completion you'll see alert window which report you about compilation result.
   
   
9. If compilation was successful a new GDScript will be created in a specified directory.
10. Use script in you project.

Mapping of protocol buffers datatypes to GDScript

Protobuf	GDScript	GDScript typeof
int32, uint32, sint32, fixed32, sfixed32 int64, uint64, sint64, fixed64, sfixed64	int	TYPE_INT
float	double / real note: number after unpacking will be single precision	TYPE_REAL
double	double / real	TYPE_REAL
bool	bool	TYPE_BOOL
enum	enum / int	TYPE_INT
string	String	TYPE_STRING
bytes	PoolByteArray	TYPE_RAW_ARRAY
oneof	fields described in oneof note: fields are not grouped into a structure, but you can set the value for only one field	different
map	Dictionary	TYPE_DICTIONARY
message	class	TYPE_OBJECT
repeated fields	Array	TYPE_ARRAY

Default values

Protobuf version 2

Initially all fields setted as null.
Default values in .proto syntax not supported.
Repeated fields are setted as empty Array.

Protobuf version 3

Initially all fields setted to default values specified in Protobuf manual.
Repeated fields are setted as empty Array.

Using generated .gd file in Godot project

1. Open the script in which Protobuf will be used.
2. Preload previously generated script:

const MyProto = preload("res://my_proto.gd")

3. Use previously described messages as GDScript classes. Example, we have .proto file:

syntax = "proto3";
message A {
    double f1 = 1;
    B f2 = 2;
}

Pack (serialization) message

Packed message must be instanced as GDScript class object directly.
Pack message A:

# Create packed class (message)
var a = MyProto.A.new()
# Example, set field f1
a.set_f1(12.554)
# Pack message A
# Use to_bytes() method, it's return PoolByteArray
var packed_bytes = a.to_bytes()

Unpack (deserialization) message

Unpacked message must be instanced as GDScript class object directly.
Re-calling from_bytes() of the same object instance is not allowed. You must create new object instance.
Unpack message A:

# Create unpacked class (message)
var a = MyProto.A.new()
# Unpack byte sequence to class (message) A.
# Use from_bytes(PoolByteArray my_byte_sequence) method
var result_code = a.from_bytes(my_byte_sequence)
# result_code must be checked (see Unpack result codes section)
if result_code == MyProto.PB_ERR.NO_ERRORS:
    print("OK")
else:
    return
# Use class 'a' fields. Example, get field f1
var f1 = a.get_f1()

Unpack result codes

from_bytes() method returns a success or an error state.
User must check the result code to make sure the unpacking is correct (see 'Unpack message' section above).
Result codes (enum PB_ERR) are presented in table below.

Unpack result code	int representation	Description
NO_ERRORS	0	Success
VARINT_NOT_FOUND	-1	Parse error. Byte sequence does not contains varint attribute, but varint is described in .proto file.
REPEATED_COUNT_NOT_FOUND	-2	Parse error. Byte sequence contains negative size of repeated block.
REPEATED_COUNT_MISMATCH	-3	Parse error. Byte sequence size less than field type size or block size.
LENGTHDEL_SIZE_NOT_FOUND	-4	Parse error. Byte sequence contains negative size of length delimited field type.
LENGTHDEL_SIZE_MISMATCH	-5	Parse error. Byte sequence size less than length delimited field type size.
PACKAGE_SIZE_MISMATCH	-6	Parse error. Byte sequence size less than package required length.
UNDEFINED_STATE	-7	Error. Unspecified error.
PARSE_INCOMPLETE	-8	Byte sequence error. Byte sequence is correct and corresponds to the .proto descriptor, but it's size is incomplete. The package (byte sequence) did not come completely.
REQUIRED_FIELDS	-9	Sender error. For Protobuf v2. Byte sequence is correct and corresponds to the .proto descriptor, but not all required fields are filled (data is missing in the byte sequence).

API

1. Scalar types

Scalar types: int32, uint32, sint32, fixed32, sfixed32, int64, uint64, sint64, fixed64, sfixed64, float, double, bool.

Set value

Use method set_<field_name>(value). Sets field value.

Get value

Use method get_<field_name>(). Returns field value.

Example

.proto-file

syntax = "proto3";
message A {
    double f1 = 1;
    int32 f2 = 2;
}

GDScript. Using set

var a = MyProto.A.new()
a.set_f1(12.554)
a.set_f2(500)

GDScript. Using get

var a = MyProto.A.new()
var state = a.from_bytes(byte_sequence)
# First you have to check the 'state' ...
var my_field_f1 = a.get_f1()
var my_field_f2 = a.get_f2()

2. String

Use similarly to scalar types.

Set value

Use method set_<field_name>(value). Sets field value.

Get value

Use method get_<field_name>(). Returns field value.

Example

.proto-file

syntax = "proto3";
message A {
    string f1 = 1;
}

GDScript. Using set

var a = MyProto.A.new()
a.set_f1("my string")

GDScript. Using get

var a = MyProto.A.new()
var state = a.from_bytes(byte_sequence)
# First you have to check the 'state' ...
var my_field_f1 = a.get_f1()

3. Bytes

Use similarly to scalar types.

Set value

Use method set_<field_name>(value). Sets field value.

Get value

Use method get_<field_name>(). Returns field value as PoolByteArray.

Example

.proto-file

syntax = "proto3";
message A {
    bytes f1 = 1;
    bytes f2 = 2;
}

GDScript. Using set

var a = MyProto.A.new()
# Correct both
a.set_f1([1,2,3,4,5])
a.set_f2(PoolByteArray([0,3,4,5,7]))

GDScript. Using get

var a = MyProto.A.new()
var state = a.from_bytes(byte_sequence)
# First you have to check the 'state' ...
var my_pool_byte_array_f1 = a.get_f1()

4. Enum

Use similarly to scalar types, but values should be taken from Enum which was generated by compiler.
Generated Enums are named according to the following rule:
<message root>.<message inner>. ... <enum name>
Using enum name in GDScript:
<preloaded/loaded resource instance name>.<class root>.<class inner>. ... <enum name>

Set value

Use method set_<field_name>(value). Sets field value.

Get value

Use method get_<field_name>(). Returns field value.

Example

.proto-file

syntax = "proto3";
enum TestEnum {
    VALUE_0 = 0;
    VALUE_1 = 1;
    VALUE_2 = 2;
}

message B {
    enum BEnum {
        BVALUE_0 = 0;
        BVALUE_1 = 1;
        BVALUE_2 = 2;
    }
}

message A {
    TestEnum f1 = 1;
    B.BEnum f2 = 2;
}

GDScript. Using set

var a = MyProto.A.new()
a.set_f1(MyProto.TestEnum.VALUE_1)
a.set_f2(MyProto.B.BEnum.BVALUE_2)

GDScript. Using get

var a = MyProto.A.new()
var state = a.from_bytes(byte_sequence)
# First you have to check the 'state' ...
var my_field_f1 = a.get_f1()
if my_field_f1 == MyProto.TestEnum.VALUE_1:
    print("OK value-1")

5. Oneof

Use similarly to scalar types, but you can set the value for only one field grouped in oneof.
Oneof group name not used in GDScript.
If you set one field of oneof group another fields will be cleared automatically.

Set value

Use method set_<field_name>(value). Sets field value.

Get value

Use method get_<field_name>(). Returns field value.

Has value

Use method has_<field_name>(). Returns true if value is been setted in byte_sequence.

Example

.proto-file

syntax = "proto3";
message A {
    oneof my_oneof {
        string      f1 = 1;
        int32       f2 = 2;
        map<int32, int32> f3 = 3;
    }
}

GDScript. Using set

var a = MyProto.A.new()
a.set_f1("my string")
# if you set f2: f1 and f3 will be setted to default values (or null for Protobuf v2)
a.set_f2(10)

GDScript. Using get

var a = MyProto.A.new()
var state = a.from_bytes(byte_sequence)
# First you have to check the 'state' ...
var my_field_f1 = a.get_f1()

GDScript. Using has

var a = MyProto.A.new()
var state = a.from_bytes(byte_sequence)
# First you have to check the 'state' ...
if a.has_f1():
    print("F1")
elif a.has_f2():
    print("F2")

6. Map

Add value

For non-message map values used method:
add_<field_name>(key, value). Append one key-value pair to Dictionary (map) field.

If map value is message (class) used method:
add_<field_name>(key). Append one key-value pair to Dictionary (map) field and return value object instance.

Get value

Use method get_<field_name>(). Returns GDScript Dictionary (map).

Example

.proto-file

syntax = "proto3";
message A {
    message B {
        int32 f1 = 1;
        int32 f2 = 2;
    }
    map<int32, string> f1 = 1;
    map<int32, B> f2 = 2;
}

GDScript. Using add

var a = MyProto.A.new()
a.add_f1(1, "one")
a.add_f1(2, "two")
a.add_f1(4, "four")

var b
b = a.add_f2(10)
b.set_f1(100)
b.set_f2(200)
b = a.add_f2(20)
b.set_f1(1000)
b.set_f2(2000)

GDScript. Using get

var a = MyProto.A.new()
var state = a.from_bytes(byte_sequence)
# First you have to check the 'state' ...
var my_dict_f1 = a.get_f1()

7. Message

Set value

Use method new_<field_name>(). Create object instance, sets as field value and returns instance.

Get value

Use method get_<field_name>(). Returns object instance.

Example

.proto-file

syntax = "proto3";
message A {
    message B {
        int64 Bf1 = 1;
        float Bf2 = 2;
    }
    message C {
        string Cf1 = 1;
        B Cf2 = 2;
    }
    
    int32 Af1 = 1;
    C Af2 = 2;
}

GDScript. Using new (set)

var a = MyProto.A.new()
a.set_Af1(10)
var c = a.new_Af2()
c.set_Cf1("my string")
var b = c.new_Cf2()
b.set_Bf1(20)
b.set_Bf2(2.5)

GDScript. Using get

var a = MyProto.A.new()
var state = a.from_bytes(byte_sequence)
# First you have to check the 'state' ...
var my_class_instance_c = a.get_Af2()
var my_int32 = my_class_instance_c.get_Af1()
# ...

8. Repeated

Add value for non-message types

Use method add_<field_name>(value). Append value to Array.

Add value for message fields

Use method add_<field_name>(). Create object instance, sets as next Array element and returns instance.

Get value

Use method get_<field_name>(). Returns Array of fields.

Example

.proto-file

syntax = "proto3";
message A {
    message B {
        int64 Bf1 = 1;
        float Bf2 = 2;
    }
    
    repeated int32 Af1 = 1;
    repeated B Af2 = 2;
}

GDScript. Using add

var a = MyProto.A.new()

a.add_Af1(10)
a.add_Af1(20)
a.add_Af1(30)

var b
b = a.add_Af2()
b.set_Bf1(100)
b.set_Bf2(1.5)

b = a.add_Af2()
b.set_Bf1(200)
b.set_Bf2(2.5)

GDScript. Using get

var a = MyProto.A.new()
var state = a.from_bytes(byte_sequence)
# First you have to check the 'state' ...
var my_array_b = a.get_Af2()
for inst in my_array_b:
    print(inst.get_Bf1())

9. Debug method to_string()

All message classes have to_string() method.
to_sting() generate debug string, which contains field names and their values. Default values are ignored.

String output format:

field_<type> - field name

field_int: 12;
field_float: 12.34;
field_bool: True;
field_string: "test";
field_enum: ENUM::2;

field_message_1: {
  field_message_2: {
    field_int: 12;
    field_float: 12.34;
  }
  field_bool: True;
  field_string: "test";
};

field_repeated: [
  0: {
    field_int: 123;
    field_bool: True;
  },
  1: {
    field_int: 454;
    field_bool: False;
  }
];

field_repeated: [
  1: 2, 
  2: 3, 
  3: 4
];

field_map: (
  "key1": "value1",
  "key2": "value2"
);

field_map: (
  "object1": {
    field_int: 123;
    field_bool: True;
  },
  "object2": {
    field_int: 454;
    field_bool: False;
  }
);

field_bytes: <1, 2, 4, 5>;
field_empty_message: {};

Example

# Debug print, where "message" - any Protobuf class (message)
print(message.to_string())

Related links

Google Protobuf: https://developers.google.com/protocol-buffers/docs/overview
Godot engine: http://godotengine.org
Godot docs: http://docs.godotengine.org/en/3.0/
Godobuf test suites: https://github.com/kittenseater/godobuf-test
https://github.com/kittenseater/godobuf-gen-v2
https://github.com/kittenseater/godobuf-gen-v3