Standard encoding/json marshaller interface support.

bootstrap/bootstrap.go

@@ -20,8 +20,9 @@ type Generator struct {
 	PkgPath, PkgName string
 	Types            []string
 
-	SnakeCase bool
-	OmitEmpty bool
+	NoStdMarshalers bool
+	SnakeCase       bool
+	OmitEmpty       bool
 
 	OutName   string
 	BuildTags string
@@ -78,6 +79,9 @@ func (g *Generator) writeMain() (path string, err error) {
 	if g.OmitEmpty {
 		fmt.Fprintln(f, "  g.OmitEmpty()")
 	}
+	if g.NoStdMarshalers {
+		fmt.Fprintln(f, "  g.NoStdMarshalers()")
+	}
 	for _, v := range g.Types {
 		fmt.Fprintln(f, "  g.Add(pkg."+v+"{})")
 	}

easyjson/main.go

@@ -12,6 +12,7 @@ import (
 
 var buildTags = flag.String("build_tags", "", "build tags to add to generated file")
 var snakeCase = flag.Bool("snake_case", false, "use snake_case names instead of CamelCase by default")
+var noStdMarshalers = flag.Bool("no_std_marshalers", false, "don't generate MarshalJSON/UnmarshalJSON methods")
 var omitEmpty = flag.Bool("omit_empty", false, "omit empty fields by default")
 var allStructs = flag.Bool("all", false, "generate un-/marshallers for all structs in a file")
 var leaveTemps = flag.Bool("leave_temps", false, "do not delete temporary files")
@@ -31,15 +32,16 @@ func generate(fname string) (err error) {
 	}
 
 	g := bootstrap.Generator{
-		BuildTags:  *buildTags,
-		PkgPath:    p.PkgPath,
-		PkgName:    p.PkgName,
-		Types:      p.StructNames,
-		SnakeCase:  *snakeCase,
-		OmitEmpty:  *omitEmpty,
-		LeaveTemps: *leaveTemps,
-		OutName:    outName,
-		StubsOnly:  *stubs,
+		BuildTags:       *buildTags,
+		PkgPath:         p.PkgPath,
+		PkgName:         p.PkgName,
+		Types:           p.StructNames,
+		SnakeCase:       *snakeCase,
+		NoStdMarshalers: *noStdMarshalers,
+		OmitEmpty:       *omitEmpty,
+		LeaveTemps:      *leaveTemps,
+		OutName:         outName,
+		StubsOnly:       *stubs,
 	}
 
 	if err := g.Run(); err != nil {

gen/decoder.go

@@ -1,6 +1,7 @@
 package gen
 
 import (
+	"encoding/json"
 	"fmt"
 	"reflect"
 	"strings"
@@ -42,6 +43,14 @@ func (g *Generator) genTypeDecoder(t reflect.Type, out string, indent int) error
 		return nil
 	}
 
+	unmarshalerIface = reflect.TypeOf((*json.Unmarshaler)(nil)).Elem()
+	if reflect.PtrTo(t).Implements(unmarshalerIface) {
+		fmt.Fprintln(g.out, ws+"if data := in.Raw(); in.Ok() {")
+		fmt.Fprintln(g.out, ws+"  in.AddError( ("+out+").UnmarshalJSON(data) )")
+		fmt.Fprintln(g.out, ws+"}")
+		return nil
+	}
+
 	// Check whether type is primitive, needs to be done after interface check.
 	if dec := primitiveDecoders[t.Kind()]; dec != "" {
 		fmt.Fprintln(g.out, ws+out+" = "+dec)
@@ -224,11 +233,14 @@ func (g *Generator) genStructUnmarshaller(t reflect.Type) error {
 	fname := g.getStructDecoderName(t)
 	typ := g.getType(t)
 
-	fmt.Fprintln(g.out, "func (v *"+typ+") UnmarshalJSON(data []byte) error {")
-	fmt.Fprintln(g.out, "  r := jlexer.Lexer{Data: data}")
-	fmt.Fprintln(g.out, "  "+fname+"(&r, v)")
-	fmt.Fprintln(g.out, "  return r.Error()")
-	fmt.Fprintln(g.out, "}")
+	if !g.noStdMarshalers {
+		fmt.Fprintln(g.out, "func (v *"+typ+") UnmarshalJSON(data []byte) error {")
+		fmt.Fprintln(g.out, "  r := jlexer.Lexer{Data: data}")
+		fmt.Fprintln(g.out, "  "+fname+"(&r, v)")
+		fmt.Fprintln(g.out, "  return r.Error()")
+		fmt.Fprintln(g.out, "}")
+	}
+
 	fmt.Fprintln(g.out, "func (v *"+typ+") UnmarshalEasyJSON(l *jlexer.Lexer) {")
 	fmt.Fprintln(g.out, "  "+fname+"(l, v)")
 	fmt.Fprintln(g.out, "}")

gen/encoder.go

@@ -1,6 +1,7 @@
 package gen
 
 import (
+	"encoding/json"
 	"fmt"
 	"reflect"
 	"strconv"
@@ -39,6 +40,12 @@ func (g *Generator) genTypeEncoder(t reflect.Type, in string, indent int) error
 		return nil
 	}
 
+	marshalerIface = reflect.TypeOf((*json.Marshaler)(nil)).Elem()
+	if reflect.PtrTo(t).Implements(marshalerIface) {
+		fmt.Fprintln(g.out, ws+"out.Raw( ("+in+").MarshalJSON() )")
+		return nil
+	}
+
 	// Check whether type is primitive, needs to be done after interface check.
 	if enc := primitiveEncoders[t.Kind()]; enc != "" {
 		fmt.Fprintln(g.out, ws+enc+"("+in+")")
@@ -198,11 +205,13 @@ func (g *Generator) genStructMarshaller(t reflect.Type) error {
 	fname := g.getStructEncoderName(t)
 	typ := g.getType(t)
 
-	fmt.Fprintln(g.out, "func (v *"+typ+") MarshalJSON() ([]byte, error) {")
-	fmt.Fprintln(g.out, "  w := jwriter.Writer{}")
-	fmt.Fprintln(g.out, "  "+fname+"(&w, v)")
-	fmt.Fprintln(g.out, "  return w.Buffer.BuildBytes(), w.Error")
-	fmt.Fprintln(g.out, "}")
+	if !g.noStdMarshalers {
+		fmt.Fprintln(g.out, "func (v *"+typ+") MarshalJSON() ([]byte, error) {")
+		fmt.Fprintln(g.out, "  w := jwriter.Writer{}")
+		fmt.Fprintln(g.out, "  "+fname+"(&w, v)")
+		fmt.Fprintln(g.out, "  return w.Buffer.BuildBytes(), w.Error")
+		fmt.Fprintln(g.out, "}")
+	}
 
 	fmt.Fprintln(g.out, "func (v *"+typ+") MarshalEasyJSON(w *jwriter.Writer) {")
 	fmt.Fprintln(g.out, "  "+fname+"(w, v)")

gen/generator.go

@@ -29,8 +29,9 @@ type Generator struct {
 
 	varCounter int
 
-	omitEmpty bool
-	namer     FieldNamer
+	noStdMarshalers bool
+	omitEmpty       bool
+	namer           FieldNamer
 
 	// package path to local alias map for tracking imports
 	imports map[string]string
@@ -85,6 +86,12 @@ func (g *Generator) UseSnakeCase() {
 	g.namer = SnakeCaseFieldNamer{}
 }
 
+// NoStdMarshalers instructs not to generate standard MarshalJSON/UnmarshalJSON
+// methods (only the custom interface).
+func (g *Generator) NoStdMarshalers() {
+	g.noStdMarshalers = true
+}
+
 // OmitEmpty triggers `json=",omitempty"` behaviour by default.
 func (g *Generator) OmitEmpty() {
 	g.omitEmpty = true

tests/basic_test.go

@@ -23,6 +23,7 @@ var testCases = []struct {
 	{&omitEmptyDefaultValue, omitEmptyDefaultString},
 	{&optsValue, optsString},
 	{&rawValue, rawString},
+	{&stdMarshalerValue, stdMarshalerString},
 }
 
 func TestMarshal(t *testing.T) {

tests/data.go

@@ -3,6 +3,7 @@ package tests
 import (
 	"fmt"
 	"math"
+	"time"
 
 	"github.com/mailru/easyjson"
 	"github.com/mailru/easyjson/opt"
@@ -200,3 +201,10 @@ var rawString = `{` +
 	`"Field":{"a" : "b"},` +
 	`"Field2":"test"` +
 	`}`
+
+type StdMarshaler struct {
+	T time.Time
+}
+
+var stdMarshalerValue = StdMarshaler{T: time.Date(2016, 01, 02, 14, 15, 10, 0, time.UTC)}
+var stdMarshalerString = `{"T":"2016-01-02T14:15:10Z"}`