internal/jsonrpc2_v2: an updated jsonrpc2 library

Change-Id: I609173baa6842d33068a7e9596d54f03d89c5401
Reviewed-on: https://go-review.googlesource.com/c/tools/+/292169
Run-TryBot: Ian Cottrell <iancottrell@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Ian Cottrell <iancottrell@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>

internal/jsonrpc2/wire.go

@@ -0,0 +1,74 @@
+// Copyright 2018 The Go MCP SDK Authors. All rights reserved.
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file.
+
+package jsonrpc2
+
+import (
+	"encoding/json"
+)
+
+// This file contains the go forms of the wire specification.
+// see http://www.jsonrpc.org/specification for details
+
+var (
+	// ErrUnknown should be used for all non coded errors.
+	ErrUnknown = NewError(-32001, "JSON RPC unknown error")
+	// ErrParse is used when invalid JSON was received by the server.
+	ErrParse = NewError(-32700, "JSON RPC parse error")
+	// ErrInvalidRequest is used when the JSON sent is not a valid Request object.
+	ErrInvalidRequest = NewError(-32600, "JSON RPC invalid request")
+	// ErrMethodNotFound should be returned by the handler when the method does
+	// not exist / is not available.
+	ErrMethodNotFound = NewError(-32601, "JSON RPC method not found")
+	// ErrInvalidParams should be returned by the handler when method
+	// parameter(s) were invalid.
+	ErrInvalidParams = NewError(-32602, "JSON RPC invalid params")
+	// ErrInternal indicates a failure to process a call correctly
+	ErrInternal = NewError(-32603, "JSON RPC internal error")
+
+	// The following errors are not part of the json specification, but
+	// compliant extensions specific to this implimentation.
+
+	// ErrServerOverloaded is returned when a message was refused due to a
+	// server being temporarily unable to accept any new messages.
+	ErrServerOverloaded = NewError(-32000, "JSON RPC overloaded")
+)
+
+const wireVersion = "2.0"
+
+// wireCombined has all the fields of both Request and Response.
+// We can decode this and then work out which it is.
+type wireCombined struct {
+	VersionTag string          `json:"jsonrpc"`
+	ID         interface{}     `json:"id,omitempty"`
+	Method     string          `json:"method,omitempty"`
+	Params     json.RawMessage `json:"params,omitempty"`
+	Result     json.RawMessage `json:"result,omitempty"`
+	Error      *wireError      `json:"error,omitempty"`
+}
+
+// wireError represents a structured error in a Response.
+type wireError struct {
+	// Code is an error code indicating the type of failure.
+	Code int64 `json:"code"`
+	// Message is a short description of the error.
+	Message string `json:"message"`
+	// Data is optional structured data containing additional information about the error.
+	Data json.RawMessage `json:"data,omitempty"`
+}
+
+// NewError returns an error that will encode on the wire correctly.
+// The standard codes are made available from this package, this function should
+// only be used to build errors for application specific codes as allowed by the
+// specification.
+func NewError(code int64, message string) error {
+	return &wireError{
+		Code:    code,
+		Message: message,
+	}
+}
+
+func (err *wireError) Error() string {
+	return err.Message
+}