# Language Server Protocol for golang

Language Server Protocol implementation in Go.

## Design notes

The package does not include JSON RPC handling as that is better left to other packages.

## Example

Example code using [github.com/sourcegraph/jsonrpc2](https://github.com/sourcegraph/jsonrpc2)

```go

import (
    "fmt"
    "io"
    "context"
	"encoding/json"
	"github.com/sourcegraph/jsonrpc2"
)

func handler(ctx context.Context, conn *jsonrpc2.Conn, req *jsonrpc2.Request) (any, error) {

    switch req.Method {
    case protocol.MethodInitialize:
        var params protocol.InitializeParams
        if err := json.Unmarshal(*req.Params, &params); err != nil {
            return nil, err
        }
        // handle initialize
	case protocol.MethodTextDocumentDidChange:
		var params protocol.DidChangeTextDocumentParams
		if err := json.Unmarshal(*req.Params, &params); err != nil {
			return nil, err
		}
        // handle did change
	default:
		// Respond with a method not found error
		return nil, &jsonrpc2.Error{
			Code:    jsonrpc2.CodeMethodNotFound,
			Message: fmt.Sprintf("Method %s not found", req.Method),
		}
    }
    return nil, nil
}

func (s Server) Run(ctx context.Context, conn io.ReadWriteCloser) error {
	stream := jsonrpc2.NewBufferedStream(conn, jsonrpc2.VSCodeObjectCodec{})
	rpc := jsonrpc2.NewConn(ctx, stream, jsonrpc2.HandlerWithError(s.dispatch))

	select {
	case <-ctx.Done():
		return fmt.Errorf("context closed")
	case <-rpc.DisconnectNotify():
		return nil
	}
}
```

# Author

Henrik Hautakoski <henrik@shufflingpixels.com>