LuaPbIntf

Lua Protobuf interface.

Binding Protobuf to Lua with lua-intf, supporting lua53 and proto3.

LuaPbIntf is inspired by luapb, but has been rewritten to take advantage of lua-intf, which makes the binding easier to use and easier to understand.

LuaPbIntf will dynamic load Protocol Buffer message definition files .proto without code generation.

LuaPbIntf use lua table to present Message, encode() to encode lua message table to string, and decode() to decode string to lua message table.

Differ from luapb

• Support proto3
• Support service
• Able to set the proto path
• luapb skips some types such as: TYPE_SFIXED32. See issue.

Build

Build with conan

1. Install conan.
2. Add conan repositories
   • conan remote add remote_bintray_bincrafters https://api.bintray.com/conan/bincrafters/public-conan
   • conan remote add remote_bintray_jinq0123 https://api.bintray.com/conan/jinq0123/test
3. conan create . user/channel --build missing
   • The result luapbintf.dll/luapbintf.so is in ~/.conan/data/luapbintf/0.1/user/channel/package/...
   • Add build settings like: conan create user/channel --build missing -s arch=x86

Without conan (depricated)

Init third_party dir first, see third_party/README.md. Then use premake5 to generate VS2015 sln or Makefile to build. See premake/premake5.bat

On Windows, it is recommended by google that you use static protobuf only. On Linux, you may need to recompile libprotobuf.a with -fPIC, or link libprotobuf.so.

Link error

error LNK2019: unresolved external symbol "void __cdecl lua_settop(struct lua_State *,int)" (?lua_settop@@YAXPAUlua_State@@H@Z)

Please see issue #2.

By default, it expects the Lua library to build under C++. If you really want to use Lua library compiled under C, you can define LUAINTF_LINK_LUA_COMPILED_IN_CXX to 0.

Run test

See test/README.md

Example

Encode and Decode

local pb = require("luapbintf")

pb.import_proto_file("test.proto")

local msg = { uid = 12345 }
local sz = pb.encode("test.TestMsg", msg)

local msg2 = pb.decode("test.TestMsg", sz)
assert(msg2.uid == 12345)

Rpc

    assert(pb.get_rpc_input_name("test.Test", "Foo") == "test.TestMsg")
    assert(pb.get_rpc_output_name("test.Test", "Foo") == "test.CommonMsg")

Map field

local msgs = {}
msgs["k1"] = {}
msgs["k2"] = {}
pb.encode("test.TestMsg", { msgs = msgs })

Oneof field

    local msg = { msg2 = {} }
    local s = pb.encode("test.TestMsg", msg)
    local result = pb.decode("test.TestMsg", s)
    assert(result.name == "")
    assert(result.name2 == nil)
    assert(result.msg2)

Type Convertion

Number will be converted to string if necessary.

    local msg = { name = 12345 }
    local s = pb.encode("test.TestMsg", msg)
    assert(pb.decode("test.TestMsg", s).name == "12345")

Integer will be converted from one type to another. Such as from int64 4294967296 to int32 0:

    local msg = { n32 = 4294967296 + 123 }
    assert(msg.n32 == 4294967296 + 123)
    local s = pb.encode("test.TestMsg", msg)
    local msg2 = pb.decode("test.TestMsg", s)
    assert(msg2.n32 == 123)

String can be converted to integer or float:

    local msg = { d = "12345e-67" }
    local s = pb.encode("test.TestMsg", msg)
    assert(pb.decode("test.TestMsg", s).d == 12345e-67)

Can not convert float to integer.

> msg = { n32 = 1.1 }
> pb.encode("test.TestMsg", msg)
stdin:1: bad argument #-1 to 'encode' (number has no integer representation)

Enum is integer, but input string enum will be converted to integer.

    local msg = { cmd = "CMD_TYPE_CHECK" }
    local s = pb.encode("test.TestMsg", msg)
    assert(pb.decode("test.TestMsg", s).cmd == 2)

Repeated field is a lua array table and it is read from index 1 to len, ignoring others.

    local msg = { names = {"n1", "n2", "n3", [0] = "n1", [100] = "n100"} }
    local s = pb.encode("test.TestMsg", msg)
    local msg2 = pb.decode("test.TestMsg", s)
    assert(#msg2.names == 3)

Proto2 Extension

Proto2 extension is not supported, which is replaced by Any type in proto3.

Reference

See doc/reference.md.

Known Bugs

• Error in coroutine. See issue #6, #17. There is a patch: SteveKChiu/lua-intf#131