Collapse the code package into jrpc2. (#97)

After removing the registration hooks in #91, what is left of the code package
is too small to deserve its own identity. Collapse the package into the root
jrpc2 package.

- Rename the code.FromError helper to jrpc2.ErrorCode.
- Update documentation.

Updates #46.

README.md

@@ -7,12 +7,10 @@ There is also a working [example in the Go playground](https://go.dev/play/p/Gdd
 
 ## Packages
 
-*  Package [jrpc2](http://godoc.org/github.com/creachadair/jrpc2) implements the base client and server.
+*  Package [jrpc2](http://godoc.org/github.com/creachadair/jrpc2) implements the base client and server and standard error codes.
 
 *  Package [channel](http://godoc.org/github.com/creachadair/jrpc2/channel) defines the communication channel abstraction used by the server & client.
 
-*  Package [code](http://godoc.org/github.com/creachadair/jrpc2/code) defines standard error codes as defined by the JSON-RPC 2.0 protocol.
-
 *  Package [handler](http://godoc.org/github.com/creachadair/jrpc2/handler) defines support for adapting functions to service methods.
 
 *  Package [jhttp](http://godoc.org/github.com/creachadair/jrpc2/jhttp) allows clients and servers to use HTTP as a transport.

base.go

@@ -8,8 +8,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"strings"
-
-	"github.com/creachadair/jrpc2/code"
 )
 
 // An Assigner assigns a Handler to handle the specified method name, or nil if
@@ -236,9 +234,9 @@ func isServiceName(s string) bool {
 // error types. If err is not a context error, it is returned unchanged.
 func filterError(e *Error) error {
 	switch e.Code {
-	case code.Cancelled:
+	case Cancelled:
 		return context.Canceled
-	case code.DeadlineExceeded:
+	case DeadlineExceeded:
 		return context.DeadlineExceeded
 	}
 	return e

client.go

@@ -11,7 +11,6 @@ import (
 	"sync"
 
 	"github.com/creachadair/jrpc2/channel"
-	"github.com/creachadair/jrpc2/code"
 )
 
 // A Client is a JSON-RPC 2.0 client. The client sends requests and receives
@@ -210,7 +209,7 @@ func (c *Client) send(ctx context.Context, reqs jmessages) ([]*Response, error)
 	// on a closing path.
 	b, err := reqs.toJSON()
 	if err != nil {
-		return nil, Errorf(code.InternalError, "marshaling request failed: %v", err)
+		return nil, Errorf(InternalError, "marshaling request failed: %v", err)
 	}
 
 	var pends []*Response
@@ -266,9 +265,9 @@ func (c *Client) waitComplete(pctx context.Context, id string, p *Response) {
 
 	var jerr *Error
 	if c.err != nil && !isUninteresting(c.err) {
-		jerr = &Error{Code: code.InternalError, Message: c.err.Error()}
+		jerr = &Error{Code: InternalError, Message: c.err.Error()}
 	} else if err != nil {
-		jerr = &Error{Code: code.FromError(err), Message: err.Error()}
+		jerr = &Error{Code: ErrorCode(err), Message: err.Error()}
 	}
 
 	p.ch <- &jmessage{
@@ -427,7 +426,7 @@ func (c *Client) marshalParams(ctx context.Context, method string, params any) (
 	if fb := firstByte(pbits); fb != '[' && fb != '{' && !isNull(pbits) {
 		// JSON-RPC requires that if parameters are provided at all, they are
 		// an array or an object.
-		return nil, &Error{Code: code.InvalidRequest, Message: "invalid parameters: array or object required"}
+		return nil, &Error{Code: InvalidRequest, Message: "invalid parameters: array or object required"}
 	}
 	return pbits, nil
 }

code/code.go → code.go

@@ -1,15 +1,15 @@
 // Copyright (C) 2017 Michael J. Fromberger. All Rights Reserved.
 
 // Package code defines error code values used by the jrpc2 package.
-package code
+package jrpc2
 
 import (
 	"context"
 	"errors"
 	"fmt"
 )
 
-// A Code is an error response code.
+// A Code is an error response.
 //
 // Code values from and including -32768 to -32000 are reserved for pre-defined
 // JSON-RPC errors.  Any code within this range, but not defined explicitly
@@ -49,9 +49,9 @@ func (c codeError) Is(err error) bool {
 	return ok && v.ErrCode() == Code(c)
 }
 
-// Err converts c to an error value, which is nil for code.NoError and
-// otherwise an error value whose code is c and whose text is based on the
-// built-in string for c if one exists.
+// Err converts c to an error value, which is nil for NoError and otherwise an
+// error value whose code is c and whose text is based on the built-in string
+// for c if one exists.
 func (c Code) Err() error {
 	if c == NoError {
 		return nil
@@ -69,7 +69,7 @@ const (
 	InvalidParams  Code = -32602 // [std] Invalid method parameters
 	InternalError  Code = -32603 // [std] Internal JSON-RPC error
 
-	NoError          Code = -32099 // Denotes a nil error (used by FromError)
+	NoError          Code = -32099 // Denotes a nil error (used by ErrorCode)
 	SystemError      Code = -32098 // Errors from the operating environment
 	Cancelled        Code = -32097 // Request cancelled (context.Canceled)
 	DeadlineExceeded Code = -32096 // Request deadline exceeded (context.DeadlineExceeded)
@@ -88,13 +88,13 @@ var stdError = map[Code]string{
 	DeadlineExceeded: "deadline exceeded",
 }
 
-// FromError returns a Code to categorize the specified error.
-// If err == nil, it returns code.NoError.
+// ErrorCode returns a Code to categorize the specified error.
+// If err == nil, it returns jrpc2.NoError.
 // If err is (or wraps) an ErrCoder, it returns the reported code value.
-// If err is context.Canceled, it returns code.Cancelled.
-// If err is context.DeadlineExceeded, it returns code.DeadlineExceeded.
-// Otherwise it returns code.SystemError.
-func FromError(err error) Code {
+// If err is context.Canceled, it returns jrpc2.Cancelled.
+// If err is context.DeadlineExceeded, it returns jrpc2.DeadlineExceeded.
+// Otherwise it returns jrpc2.SystemError.
+func ErrorCode(err error) Code {
 	if err == nil {
 		return NoError
 	}

code/code_test.go → code_test.go

@@ -1,6 +1,6 @@
 // Copyright (C) 2017 Michael J. Fromberger. All Rights Reserved.
 
-package code_test
+package jrpc2_test
 
 import (
 	"context"
@@ -9,49 +9,49 @@ import (
 	"io"
 	"testing"
 
-	"github.com/creachadair/jrpc2/code"
+	"github.com/creachadair/jrpc2"
 )
 
-type testCoder code.Code
+type testCoder jrpc2.Code
 
-func (t testCoder) ErrCode() code.Code { return code.Code(t) }
-func (testCoder) Error() string        { return "bogus" }
+func (t testCoder) ErrCode() jrpc2.Code { return jrpc2.Code(t) }
+func (testCoder) Error() string         { return "bogus" }
 
-func TestFromError(t *testing.T) {
+func TestErrorCode(t *testing.T) {
 	tests := []struct {
 		input error
-		want  code.Code
+		want  jrpc2.Code
 	}{
-		{nil, code.NoError},
-		{testCoder(code.ParseError), code.ParseError},
-		{testCoder(code.InvalidRequest), code.InvalidRequest},
-		{fmt.Errorf("wrapped parse error: %w", code.ParseError.Err()), code.ParseError},
-		{context.Canceled, code.Cancelled},
-		{fmt.Errorf("wrapped cancellation: %w", context.Canceled), code.Cancelled},
-		{context.DeadlineExceeded, code.DeadlineExceeded},
-		{fmt.Errorf("wrapped deadline: %w", context.DeadlineExceeded), code.DeadlineExceeded},
-		{errors.New("other"), code.SystemError},
-		{io.EOF, code.SystemError},
+		{nil, jrpc2.NoError},
+		{testCoder(jrpc2.ParseError), jrpc2.ParseError},
+		{testCoder(jrpc2.InvalidRequest), jrpc2.InvalidRequest},
+		{fmt.Errorf("wrapped parse error: %w", jrpc2.ParseError.Err()), jrpc2.ParseError},
+		{context.Canceled, jrpc2.Cancelled},
+		{fmt.Errorf("wrapped cancellation: %w", context.Canceled), jrpc2.Cancelled},
+		{context.DeadlineExceeded, jrpc2.DeadlineExceeded},
+		{fmt.Errorf("wrapped deadline: %w", context.DeadlineExceeded), jrpc2.DeadlineExceeded},
+		{errors.New("other"), jrpc2.SystemError},
+		{io.EOF, jrpc2.SystemError},
 	}
 	for _, test := range tests {
-		if got := code.FromError(test.input); got != test.want {
-			t.Errorf("FromError(%v): got %v, want %v", test.input, got, test.want)
+		if got := jrpc2.ErrorCode(test.input); got != test.want {
+			t.Errorf("ErrorCode(%v): got %v, want %v", test.input, got, test.want)
 		}
 	}
 }
 
 func TestCodeIs(t *testing.T) {
 	tests := []struct {
-		code code.Code
+		code jrpc2.Code
 		err  error
 		want bool
 	}{
-		{code.NoError, nil, true},
+		{jrpc2.NoError, nil, true},
 		{0, nil, false},
-		{1, code.Code(1).Err(), true},
-		{2, code.Code(3).Err(), false},
-		{4, fmt.Errorf("blah: %w", code.Code(4).Err()), true},
-		{5, fmt.Errorf("nope: %w", code.Code(6).Err()), false},
+		{1, jrpc2.Code(1).Err(), true},
+		{2, jrpc2.Code(3).Err(), false},
+		{4, fmt.Errorf("blah: %w", jrpc2.Code(4).Err()), true},
+		{5, fmt.Errorf("nope: %w", jrpc2.Code(6).Err()), false},
 	}
 	for _, test := range tests {
 		cerr := test.code.Err()
@@ -67,11 +67,11 @@ func TestErr(t *testing.T) {
 		return e1 == e2 || (e1 != nil && e2 != nil && e1.Error() == e2.Error())
 	}
 	type test struct {
-		code code.Code
+		code jrpc2.Code
 		want error
 	}
 	tests := []test{
-		{code.NoError, nil},
+		{jrpc2.NoError, nil},
 		{0, errors.New("error code 0")},
 		{1, errors.New("error code 1")},
 		{-17, errors.New("error code -17")},
@@ -84,7 +84,7 @@ func TestErr(t *testing.T) {
 		// Codes reserved by this implementation.
 		-32098, -32097, -32096,
 	} {
-		c := code.Code(v)
+		c := jrpc2.Code(v)
 		tests = append(tests, test{
 			code: c,
 			want: errors.New(c.String()),
@@ -95,7 +95,7 @@ func TestErr(t *testing.T) {
 		if !eqv(got, test.want) {
 			t.Errorf("Code(%d).Err(): got %#v, want %#v", test.code, got, test.want)
 		}
-		if c := code.FromError(got); c != test.code {
+		if c := jrpc2.ErrorCode(got); c != test.code {
 			t.Errorf("Code(%d).Err(): got code %v, want %v", test.code, c, test.code)
 		}
 	}

error.go

@@ -6,22 +6,20 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-
-	"github.com/creachadair/jrpc2/code"
 )
 
 // Error is the concrete type of errors returned from RPC calls.
 type Error struct {
-	Code    code.Code       `json:"code"`              // the machine-readable error code
+	Code    Code            `json:"code"`              // the machine-readable error code
 	Message string          `json:"message,omitempty"` // the human-readable error message
 	Data    json.RawMessage `json:"data,omitempty"`    // optional ancillary error data
 }
 
 // Error renders e to a human-readable string for the error interface.
 func (e Error) Error() string { return fmt.Sprintf("[%d] %s", e.Code, e.Message) }
 
-// ErrCode trivially satisfies the code.ErrCoder interface for an *Error.
-func (e Error) ErrCode() code.Code { return e.Code }
+// ErrCode trivially satisfies the ErrCoder interface for an *Error.
+func (e Error) ErrCode() Code { return e.Code }
 
 // WithData marshals v as JSON and constructs a copy of e whose Data field
 // includes the result. If v == nil or if marshaling v fails, e is returned
@@ -44,22 +42,22 @@ var errServerStopped = errors.New("the server has been stopped")
 var errClientStopped = errors.New("the client has been stopped")
 
 // errEmptyMethod is the error reported for an empty request method name.
-var errEmptyMethod = &Error{Code: code.InvalidRequest, Message: "empty method name"}
+var errEmptyMethod = &Error{Code: InvalidRequest, Message: "empty method name"}
 
 // errNoSuchMethod is the error reported for an unknown method name.
-var errNoSuchMethod = &Error{Code: code.MethodNotFound, Message: code.MethodNotFound.String()}
+var errNoSuchMethod = &Error{Code: MethodNotFound, Message: MethodNotFound.String()}
 
 // errDuplicateID is the error reported for a duplicated request ID.
-var errDuplicateID = &Error{Code: code.InvalidRequest, Message: "duplicate request ID"}
+var errDuplicateID = &Error{Code: InvalidRequest, Message: "duplicate request ID"}
 
 // errInvalidRequest is the error reported for an invalid request object or batch.
-var errInvalidRequest = &Error{Code: code.ParseError, Message: "invalid request value"}
+var errInvalidRequest = &Error{Code: ParseError, Message: "invalid request value"}
 
 // errEmptyBatch is the error reported for an empty request batch.
-var errEmptyBatch = &Error{Code: code.InvalidRequest, Message: "empty request batch"}
+var errEmptyBatch = &Error{Code: InvalidRequest, Message: "empty request batch"}
 
 // errInvalidParams is the error reported for invalid request parameters.
-var errInvalidParams = &Error{Code: code.InvalidParams, Message: code.InvalidParams.String()}
+var errInvalidParams = &Error{Code: InvalidParams, Message: InvalidParams.String()}
 
 // errTaskNotExecuted is the internal sentinel error for an unassigned task.
 var errTaskNotExecuted = new(Error)
@@ -70,6 +68,6 @@ var ErrConnClosed = errors.New("client connection is closed")
 
 // Errorf returns an error value of concrete type *Error having the specified
 // code and formatted message string.
-func Errorf(code code.Code, msg string, args ...any) *Error {
+func Errorf(code Code, msg string, args ...any) *Error {
 	return &Error{Code: code, Message: fmt.Sprintf(msg, args...)}
 }

examples_test.go

@@ -11,7 +11,6 @@ import (
 	"strings"
 
 	"github.com/creachadair/jrpc2"
-	"github.com/creachadair/jrpc2/code"
 	"github.com/creachadair/jrpc2/handler"
 	"github.com/creachadair/jrpc2/internal/testutil"
 	"github.com/creachadair/jrpc2/server"
@@ -119,14 +118,14 @@ func ExampleRequest_UnmarshalParams() {
 	//
 	// Solution 1: Use the jrpc2.StrictFields helper.
 	err = req.UnmarshalParams(jrpc2.StrictFields(&t))
-	if code.FromError(err) != code.InvalidParams {
+	if jrpc2.ErrorCode(err) != jrpc2.InvalidParams {
 		log.Fatalf("UnmarshalParams strict: %v", err)
 	}
 
 	// Solution 2: Implement a DisallowUnknownFields method.
 	var p strictParams
 	err = req.UnmarshalParams(&p)
-	if code.FromError(err) != code.InvalidParams {
+	if jrpc2.ErrorCode(err) != jrpc2.InvalidParams {
 		log.Fatalf("UnmarshalParams strict: %v", err)
 	}
 

handler/handler.go

@@ -14,7 +14,6 @@ import (
 	"strings"
 
 	"github.com/creachadair/jrpc2"
-	"github.com/creachadair/jrpc2/code"
 )
 
 // A Func is wrapper for a jrpc2.Handler function.
@@ -96,7 +95,7 @@ var (
 
 	strictType = reflect.TypeOf((*interface{ DisallowUnknownFields() })(nil)).Elem()
 
-	errNoParameters = &jrpc2.Error{Code: code.InvalidParams, Message: "no parameters accepted"}
+	errNoParameters = &jrpc2.Error{Code: jrpc2.InvalidParams, Message: "no parameters accepted"}
 )
 
 // FuncInfo captures type signature information from a valid handler function.
@@ -179,7 +178,7 @@ func (fi *FuncInfo) Wrap() Func {
 		newInput = func(ctx reflect.Value, req *jrpc2.Request) ([]reflect.Value, error) {
 			in := reflect.New(arg.Elem())
 			if err := req.UnmarshalParams(wrapArg(in)); err != nil {
-				return nil, jrpc2.Errorf(code.InvalidParams, "invalid parameters: %v", err)
+				return nil, jrpc2.Errorf(jrpc2.InvalidParams, "invalid parameters: %v", err)
 			}
 			return []reflect.Value{ctx, in}, nil
 		}
@@ -188,7 +187,7 @@ func (fi *FuncInfo) Wrap() Func {
 		newInput = func(ctx reflect.Value, req *jrpc2.Request) ([]reflect.Value, error) {
 			in := reflect.New(arg) // we still need a pointer to unmarshal
 			if err := req.UnmarshalParams(wrapArg(in)); err != nil {
-				return nil, jrpc2.Errorf(code.InvalidParams, "invalid parameters: %v", err)
+				return nil, jrpc2.Errorf(jrpc2.InvalidParams, "invalid parameters: %v", err)
 			}
 			// Indirect the pointer back off for the callee.
 			return []reflect.Value{ctx, in.Elem()}, nil
@@ -333,7 +332,7 @@ func (s *arrayStub) translate(data []byte) ([]byte, error) {
 	if err := json.Unmarshal(data, &arr); err != nil {
 		return nil, err
 	} else if len(arr) != len(s.posNames) {
-		return nil, jrpc2.Errorf(code.InvalidParams, "got %d parameters, want %d",
+		return nil, jrpc2.Errorf(jrpc2.InvalidParams, "got %d parameters, want %d",
 			len(arr), len(s.posNames))
 	}
 

handler/handler_test.go

@@ -11,7 +11,6 @@ import (
 	"testing"
 
 	"github.com/creachadair/jrpc2"
-	"github.com/creachadair/jrpc2/code"
 	"github.com/creachadair/jrpc2/handler"
 	"github.com/creachadair/jrpc2/internal/testutil"
 	"github.com/google/go-cmp/cmp"
@@ -254,7 +253,7 @@ func TestFuncInfo_SetStrict(t *testing.T) {
       "Z": 25
    }}`)
 	rsp, err := fn(context.Background(), req)
-	if got := code.FromError(err); got != code.InvalidParams {
+	if got := jrpc2.ErrorCode(err); got != jrpc2.InvalidParams {
 		t.Errorf("Handler returned (%+v, %v), want InvalidParms", rsp, err)
 	}
 }