plugeth/rlp/rlpgen/gen.go
Martin Holst Swende 58d0f6440b
rlp: support for uint256 (#26898)
This adds built-in support in package rlp for encoding, decoding and generating code dealing with uint256.Int.

---------

Co-authored-by: Felix Lange <fjl@twurst.com>
2023-03-17 06:51:55 -04:00

801 lines
22 KiB
Go

// Copyright 2022 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package main
import (
"bytes"
"fmt"
"go/format"
"go/types"
"sort"
"github.com/ethereum/go-ethereum/rlp/internal/rlpstruct"
)
// buildContext keeps the data needed for make*Op.
type buildContext struct {
topType *types.Named // the type we're creating methods for
encoderIface *types.Interface
decoderIface *types.Interface
rawValueType *types.Named
typeToStructCache map[types.Type]*rlpstruct.Type
}
func newBuildContext(packageRLP *types.Package) *buildContext {
enc := packageRLP.Scope().Lookup("Encoder").Type().Underlying()
dec := packageRLP.Scope().Lookup("Decoder").Type().Underlying()
rawv := packageRLP.Scope().Lookup("RawValue").Type()
return &buildContext{
typeToStructCache: make(map[types.Type]*rlpstruct.Type),
encoderIface: enc.(*types.Interface),
decoderIface: dec.(*types.Interface),
rawValueType: rawv.(*types.Named),
}
}
func (bctx *buildContext) isEncoder(typ types.Type) bool {
return types.Implements(typ, bctx.encoderIface)
}
func (bctx *buildContext) isDecoder(typ types.Type) bool {
return types.Implements(typ, bctx.decoderIface)
}
// typeToStructType converts typ to rlpstruct.Type.
func (bctx *buildContext) typeToStructType(typ types.Type) *rlpstruct.Type {
if prev := bctx.typeToStructCache[typ]; prev != nil {
return prev // short-circuit for recursive types.
}
// Resolve named types to their underlying type, but keep the name.
name := types.TypeString(typ, nil)
for {
utype := typ.Underlying()
if utype == typ {
break
}
typ = utype
}
// Create the type and store it in cache.
t := &rlpstruct.Type{
Name: name,
Kind: typeReflectKind(typ),
IsEncoder: bctx.isEncoder(typ),
IsDecoder: bctx.isDecoder(typ),
}
bctx.typeToStructCache[typ] = t
// Assign element type.
switch typ.(type) {
case *types.Array, *types.Slice, *types.Pointer:
etype := typ.(interface{ Elem() types.Type }).Elem()
t.Elem = bctx.typeToStructType(etype)
}
return t
}
// genContext is passed to the gen* methods of op when generating
// the output code. It tracks packages to be imported by the output
// file and assigns unique names of temporary variables.
type genContext struct {
inPackage *types.Package
imports map[string]struct{}
tempCounter int
}
func newGenContext(inPackage *types.Package) *genContext {
return &genContext{
inPackage: inPackage,
imports: make(map[string]struct{}),
}
}
func (ctx *genContext) temp() string {
v := fmt.Sprintf("_tmp%d", ctx.tempCounter)
ctx.tempCounter++
return v
}
func (ctx *genContext) resetTemp() {
ctx.tempCounter = 0
}
func (ctx *genContext) addImport(path string) {
if path == ctx.inPackage.Path() {
return // avoid importing the package that we're generating in.
}
// TODO: renaming?
ctx.imports[path] = struct{}{}
}
// importsList returns all packages that need to be imported.
func (ctx *genContext) importsList() []string {
imp := make([]string, 0, len(ctx.imports))
for k := range ctx.imports {
imp = append(imp, k)
}
sort.Strings(imp)
return imp
}
// qualify is the types.Qualifier used for printing types.
func (ctx *genContext) qualify(pkg *types.Package) string {
if pkg.Path() == ctx.inPackage.Path() {
return ""
}
ctx.addImport(pkg.Path())
// TODO: renaming?
return pkg.Name()
}
type op interface {
// genWrite creates the encoder. The generated code should write v,
// which is any Go expression, to the rlp.EncoderBuffer 'w'.
genWrite(ctx *genContext, v string) string
// genDecode creates the decoder. The generated code should read
// a value from the rlp.Stream 'dec' and store it to dst.
genDecode(ctx *genContext) (string, string)
}
// basicOp handles basic types bool, uint*, string.
type basicOp struct {
typ types.Type
writeMethod string // calle write the value
writeArgType types.Type // parameter type of writeMethod
decMethod string
decResultType types.Type // return type of decMethod
decUseBitSize bool // if true, result bit size is appended to decMethod
}
func (*buildContext) makeBasicOp(typ *types.Basic) (op, error) {
op := basicOp{typ: typ}
kind := typ.Kind()
switch {
case kind == types.Bool:
op.writeMethod = "WriteBool"
op.writeArgType = types.Typ[types.Bool]
op.decMethod = "Bool"
op.decResultType = types.Typ[types.Bool]
case kind >= types.Uint8 && kind <= types.Uint64:
op.writeMethod = "WriteUint64"
op.writeArgType = types.Typ[types.Uint64]
op.decMethod = "Uint"
op.decResultType = typ
op.decUseBitSize = true
case kind == types.String:
op.writeMethod = "WriteString"
op.writeArgType = types.Typ[types.String]
op.decMethod = "String"
op.decResultType = types.Typ[types.String]
default:
return nil, fmt.Errorf("unhandled basic type: %v", typ)
}
return op, nil
}
func (*buildContext) makeByteSliceOp(typ *types.Slice) op {
if !isByte(typ.Elem()) {
panic("non-byte slice type in makeByteSliceOp")
}
bslice := types.NewSlice(types.Typ[types.Uint8])
return basicOp{
typ: typ,
writeMethod: "WriteBytes",
writeArgType: bslice,
decMethod: "Bytes",
decResultType: bslice,
}
}
func (bctx *buildContext) makeRawValueOp() op {
bslice := types.NewSlice(types.Typ[types.Uint8])
return basicOp{
typ: bctx.rawValueType,
writeMethod: "Write",
writeArgType: bslice,
decMethod: "Raw",
decResultType: bslice,
}
}
func (op basicOp) writeNeedsConversion() bool {
return !types.AssignableTo(op.typ, op.writeArgType)
}
func (op basicOp) decodeNeedsConversion() bool {
return !types.AssignableTo(op.decResultType, op.typ)
}
func (op basicOp) genWrite(ctx *genContext, v string) string {
if op.writeNeedsConversion() {
v = fmt.Sprintf("%s(%s)", op.writeArgType, v)
}
return fmt.Sprintf("w.%s(%s)\n", op.writeMethod, v)
}
func (op basicOp) genDecode(ctx *genContext) (string, string) {
var (
resultV = ctx.temp()
result = resultV
method = op.decMethod
)
if op.decUseBitSize {
// Note: For now, this only works for platform-independent integer
// sizes. makeBasicOp forbids the platform-dependent types.
var sizes types.StdSizes
method = fmt.Sprintf("%s%d", op.decMethod, sizes.Sizeof(op.typ)*8)
}
// Call the decoder method.
var b bytes.Buffer
fmt.Fprintf(&b, "%s, err := dec.%s()\n", resultV, method)
fmt.Fprintf(&b, "if err != nil { return err }\n")
if op.decodeNeedsConversion() {
conv := ctx.temp()
fmt.Fprintf(&b, "%s := %s(%s)\n", conv, types.TypeString(op.typ, ctx.qualify), resultV)
result = conv
}
return result, b.String()
}
// byteArrayOp handles [...]byte.
type byteArrayOp struct {
typ types.Type
name types.Type // name != typ for named byte array types (e.g. common.Address)
}
func (bctx *buildContext) makeByteArrayOp(name *types.Named, typ *types.Array) byteArrayOp {
nt := types.Type(name)
if name == nil {
nt = typ
}
return byteArrayOp{typ, nt}
}
func (op byteArrayOp) genWrite(ctx *genContext, v string) string {
return fmt.Sprintf("w.WriteBytes(%s[:])\n", v)
}
func (op byteArrayOp) genDecode(ctx *genContext) (string, string) {
var resultV = ctx.temp()
var b bytes.Buffer
fmt.Fprintf(&b, "var %s %s\n", resultV, types.TypeString(op.name, ctx.qualify))
fmt.Fprintf(&b, "if err := dec.ReadBytes(%s[:]); err != nil { return err }\n", resultV)
return resultV, b.String()
}
// bigIntOp handles big.Int.
// This exists because big.Int has it's own decoder operation on rlp.Stream,
// but the decode method returns *big.Int, so it needs to be dereferenced.
type bigIntOp struct {
pointer bool
}
func (op bigIntOp) genWrite(ctx *genContext, v string) string {
var b bytes.Buffer
fmt.Fprintf(&b, "if %s.Sign() == -1 {\n", v)
fmt.Fprintf(&b, " return rlp.ErrNegativeBigInt\n")
fmt.Fprintf(&b, "}\n")
dst := v
if !op.pointer {
dst = "&" + v
}
fmt.Fprintf(&b, "w.WriteBigInt(%s)\n", dst)
// Wrap with nil check.
if op.pointer {
code := b.String()
b.Reset()
fmt.Fprintf(&b, "if %s == nil {\n", v)
fmt.Fprintf(&b, " w.Write(rlp.EmptyString)")
fmt.Fprintf(&b, "} else {\n")
fmt.Fprint(&b, code)
fmt.Fprintf(&b, "}\n")
}
return b.String()
}
func (op bigIntOp) genDecode(ctx *genContext) (string, string) {
var resultV = ctx.temp()
var b bytes.Buffer
fmt.Fprintf(&b, "%s, err := dec.BigInt()\n", resultV)
fmt.Fprintf(&b, "if err != nil { return err }\n")
result := resultV
if !op.pointer {
result = "(*" + resultV + ")"
}
return result, b.String()
}
// uint256Op handles "github.com/holiman/uint256".Int
type uint256Op struct {
pointer bool
}
func (op uint256Op) genWrite(ctx *genContext, v string) string {
var b bytes.Buffer
dst := v
if !op.pointer {
dst = "&" + v
}
fmt.Fprintf(&b, "w.WriteUint256(%s)\n", dst)
// Wrap with nil check.
if op.pointer {
code := b.String()
b.Reset()
fmt.Fprintf(&b, "if %s == nil {\n", v)
fmt.Fprintf(&b, " w.Write(rlp.EmptyString)")
fmt.Fprintf(&b, "} else {\n")
fmt.Fprint(&b, code)
fmt.Fprintf(&b, "}\n")
}
return b.String()
}
func (op uint256Op) genDecode(ctx *genContext) (string, string) {
ctx.addImport("github.com/holiman/uint256")
var b bytes.Buffer
resultV := ctx.temp()
fmt.Fprintf(&b, "var %s uint256.Int\n", resultV)
fmt.Fprintf(&b, "if err := dec.ReadUint256(&%s); err != nil { return err }\n", resultV)
result := resultV
if op.pointer {
result = "&" + resultV
}
return result, b.String()
}
// encoderDecoderOp handles rlp.Encoder and rlp.Decoder.
// In order to be used with this, the type must implement both interfaces.
// This restriction may be lifted in the future by creating separate ops for
// encoding and decoding.
type encoderDecoderOp struct {
typ types.Type
}
func (op encoderDecoderOp) genWrite(ctx *genContext, v string) string {
return fmt.Sprintf("if err := %s.EncodeRLP(w); err != nil { return err }\n", v)
}
func (op encoderDecoderOp) genDecode(ctx *genContext) (string, string) {
// DecodeRLP must have pointer receiver, and this is verified in makeOp.
etyp := op.typ.(*types.Pointer).Elem()
var resultV = ctx.temp()
var b bytes.Buffer
fmt.Fprintf(&b, "%s := new(%s)\n", resultV, types.TypeString(etyp, ctx.qualify))
fmt.Fprintf(&b, "if err := %s.DecodeRLP(dec); err != nil { return err }\n", resultV)
return resultV, b.String()
}
// ptrOp handles pointer types.
type ptrOp struct {
elemTyp types.Type
elem op
nilOK bool
nilValue rlpstruct.NilKind
}
func (bctx *buildContext) makePtrOp(elemTyp types.Type, tags rlpstruct.Tags) (op, error) {
elemOp, err := bctx.makeOp(nil, elemTyp, rlpstruct.Tags{})
if err != nil {
return nil, err
}
op := ptrOp{elemTyp: elemTyp, elem: elemOp}
// Determine nil value.
if tags.NilOK {
op.nilOK = true
op.nilValue = tags.NilKind
} else {
styp := bctx.typeToStructType(elemTyp)
op.nilValue = styp.DefaultNilValue()
}
return op, nil
}
func (op ptrOp) genWrite(ctx *genContext, v string) string {
// Note: in writer functions, accesses to v are read-only, i.e. v is any Go
// expression. To make all accesses work through the pointer, we substitute
// v with (*v). This is required for most accesses including `v`, `call(v)`,
// and `v[index]` on slices.
//
// For `v.field` and `v[:]` on arrays, the dereference operation is not required.
var vv string
_, isStruct := op.elem.(structOp)
_, isByteArray := op.elem.(byteArrayOp)
if isStruct || isByteArray {
vv = v
} else {
vv = fmt.Sprintf("(*%s)", v)
}
var b bytes.Buffer
fmt.Fprintf(&b, "if %s == nil {\n", v)
fmt.Fprintf(&b, " w.Write([]byte{0x%X})\n", op.nilValue)
fmt.Fprintf(&b, "} else {\n")
fmt.Fprintf(&b, " %s", op.elem.genWrite(ctx, vv))
fmt.Fprintf(&b, "}\n")
return b.String()
}
func (op ptrOp) genDecode(ctx *genContext) (string, string) {
result, code := op.elem.genDecode(ctx)
if !op.nilOK {
// If nil pointers are not allowed, we can just decode the element.
return "&" + result, code
}
// nil is allowed, so check the kind and size first.
// If size is zero and kind matches the nilKind of the type,
// the value decodes as a nil pointer.
var (
resultV = ctx.temp()
kindV = ctx.temp()
sizeV = ctx.temp()
wantKind string
)
if op.nilValue == rlpstruct.NilKindList {
wantKind = "rlp.List"
} else {
wantKind = "rlp.String"
}
var b bytes.Buffer
fmt.Fprintf(&b, "var %s %s\n", resultV, types.TypeString(types.NewPointer(op.elemTyp), ctx.qualify))
fmt.Fprintf(&b, "if %s, %s, err := dec.Kind(); err != nil {\n", kindV, sizeV)
fmt.Fprintf(&b, " return err\n")
fmt.Fprintf(&b, "} else if %s != 0 || %s != %s {\n", sizeV, kindV, wantKind)
fmt.Fprint(&b, code)
fmt.Fprintf(&b, " %s = &%s\n", resultV, result)
fmt.Fprintf(&b, "}\n")
return resultV, b.String()
}
// structOp handles struct types.
type structOp struct {
named *types.Named
typ *types.Struct
fields []*structField
optionalFields []*structField
}
type structField struct {
name string
typ types.Type
elem op
}
func (bctx *buildContext) makeStructOp(named *types.Named, typ *types.Struct) (op, error) {
// Convert fields to []rlpstruct.Field.
var allStructFields []rlpstruct.Field
for i := 0; i < typ.NumFields(); i++ {
f := typ.Field(i)
allStructFields = append(allStructFields, rlpstruct.Field{
Name: f.Name(),
Exported: f.Exported(),
Index: i,
Tag: typ.Tag(i),
Type: *bctx.typeToStructType(f.Type()),
})
}
// Filter/validate fields.
fields, tags, err := rlpstruct.ProcessFields(allStructFields)
if err != nil {
return nil, err
}
// Create field ops.
var op = structOp{named: named, typ: typ}
for i, field := range fields {
// Advanced struct tags are not supported yet.
tag := tags[i]
if err := checkUnsupportedTags(field.Name, tag); err != nil {
return nil, err
}
typ := typ.Field(field.Index).Type()
elem, err := bctx.makeOp(nil, typ, tags[i])
if err != nil {
return nil, fmt.Errorf("field %s: %v", field.Name, err)
}
f := &structField{name: field.Name, typ: typ, elem: elem}
if tag.Optional {
op.optionalFields = append(op.optionalFields, f)
} else {
op.fields = append(op.fields, f)
}
}
return op, nil
}
func checkUnsupportedTags(field string, tag rlpstruct.Tags) error {
if tag.Tail {
return fmt.Errorf(`field %s has unsupported struct tag "tail"`, field)
}
return nil
}
func (op structOp) genWrite(ctx *genContext, v string) string {
var b bytes.Buffer
var listMarker = ctx.temp()
fmt.Fprintf(&b, "%s := w.List()\n", listMarker)
for _, field := range op.fields {
selector := v + "." + field.name
fmt.Fprint(&b, field.elem.genWrite(ctx, selector))
}
op.writeOptionalFields(&b, ctx, v)
fmt.Fprintf(&b, "w.ListEnd(%s)\n", listMarker)
return b.String()
}
func (op structOp) writeOptionalFields(b *bytes.Buffer, ctx *genContext, v string) {
if len(op.optionalFields) == 0 {
return
}
// First check zero-ness of all optional fields.
var zeroV = make([]string, len(op.optionalFields))
for i, field := range op.optionalFields {
selector := v + "." + field.name
zeroV[i] = ctx.temp()
fmt.Fprintf(b, "%s := %s\n", zeroV[i], nonZeroCheck(selector, field.typ, ctx.qualify))
}
// Now write the fields.
for i, field := range op.optionalFields {
selector := v + "." + field.name
cond := ""
for j := i; j < len(op.optionalFields); j++ {
if j > i {
cond += " || "
}
cond += zeroV[j]
}
fmt.Fprintf(b, "if %s {\n", cond)
fmt.Fprint(b, field.elem.genWrite(ctx, selector))
fmt.Fprintf(b, "}\n")
}
}
func (op structOp) genDecode(ctx *genContext) (string, string) {
// Get the string representation of the type.
// Here, named types are handled separately because the output
// would contain a copy of the struct definition otherwise.
var typeName string
if op.named != nil {
typeName = types.TypeString(op.named, ctx.qualify)
} else {
typeName = types.TypeString(op.typ, ctx.qualify)
}
// Create struct object.
var resultV = ctx.temp()
var b bytes.Buffer
fmt.Fprintf(&b, "var %s %s\n", resultV, typeName)
// Decode fields.
fmt.Fprintf(&b, "{\n")
fmt.Fprintf(&b, "if _, err := dec.List(); err != nil { return err }\n")
for _, field := range op.fields {
result, code := field.elem.genDecode(ctx)
fmt.Fprintf(&b, "// %s:\n", field.name)
fmt.Fprint(&b, code)
fmt.Fprintf(&b, "%s.%s = %s\n", resultV, field.name, result)
}
op.decodeOptionalFields(&b, ctx, resultV)
fmt.Fprintf(&b, "if err := dec.ListEnd(); err != nil { return err }\n")
fmt.Fprintf(&b, "}\n")
return resultV, b.String()
}
func (op structOp) decodeOptionalFields(b *bytes.Buffer, ctx *genContext, resultV string) {
var suffix bytes.Buffer
for _, field := range op.optionalFields {
result, code := field.elem.genDecode(ctx)
fmt.Fprintf(b, "// %s:\n", field.name)
fmt.Fprintf(b, "if dec.MoreDataInList() {\n")
fmt.Fprint(b, code)
fmt.Fprintf(b, "%s.%s = %s\n", resultV, field.name, result)
fmt.Fprintf(&suffix, "}\n")
}
suffix.WriteTo(b)
}
// sliceOp handles slice types.
type sliceOp struct {
typ *types.Slice
elemOp op
}
func (bctx *buildContext) makeSliceOp(typ *types.Slice) (op, error) {
elemOp, err := bctx.makeOp(nil, typ.Elem(), rlpstruct.Tags{})
if err != nil {
return nil, err
}
return sliceOp{typ: typ, elemOp: elemOp}, nil
}
func (op sliceOp) genWrite(ctx *genContext, v string) string {
var (
listMarker = ctx.temp() // holds return value of w.List()
iterElemV = ctx.temp() // iteration variable
elemCode = op.elemOp.genWrite(ctx, iterElemV)
)
var b bytes.Buffer
fmt.Fprintf(&b, "%s := w.List()\n", listMarker)
fmt.Fprintf(&b, "for _, %s := range %s {\n", iterElemV, v)
fmt.Fprint(&b, elemCode)
fmt.Fprintf(&b, "}\n")
fmt.Fprintf(&b, "w.ListEnd(%s)\n", listMarker)
return b.String()
}
func (op sliceOp) genDecode(ctx *genContext) (string, string) {
var sliceV = ctx.temp() // holds the output slice
elemResult, elemCode := op.elemOp.genDecode(ctx)
var b bytes.Buffer
fmt.Fprintf(&b, "var %s %s\n", sliceV, types.TypeString(op.typ, ctx.qualify))
fmt.Fprintf(&b, "if _, err := dec.List(); err != nil { return err }\n")
fmt.Fprintf(&b, "for dec.MoreDataInList() {\n")
fmt.Fprintf(&b, " %s", elemCode)
fmt.Fprintf(&b, " %s = append(%s, %s)\n", sliceV, sliceV, elemResult)
fmt.Fprintf(&b, "}\n")
fmt.Fprintf(&b, "if err := dec.ListEnd(); err != nil { return err }\n")
return sliceV, b.String()
}
func (bctx *buildContext) makeOp(name *types.Named, typ types.Type, tags rlpstruct.Tags) (op, error) {
switch typ := typ.(type) {
case *types.Named:
if isBigInt(typ) {
return bigIntOp{}, nil
}
if isUint256(typ) {
return uint256Op{}, nil
}
if typ == bctx.rawValueType {
return bctx.makeRawValueOp(), nil
}
if bctx.isDecoder(typ) {
return nil, fmt.Errorf("type %v implements rlp.Decoder with non-pointer receiver", typ)
}
// TODO: same check for encoder?
return bctx.makeOp(typ, typ.Underlying(), tags)
case *types.Pointer:
if isBigInt(typ.Elem()) {
return bigIntOp{pointer: true}, nil
}
if isUint256(typ.Elem()) {
return uint256Op{pointer: true}, nil
}
// Encoder/Decoder interfaces.
if bctx.isEncoder(typ) {
if bctx.isDecoder(typ) {
return encoderDecoderOp{typ}, nil
}
return nil, fmt.Errorf("type %v implements rlp.Encoder but not rlp.Decoder", typ)
}
if bctx.isDecoder(typ) {
return nil, fmt.Errorf("type %v implements rlp.Decoder but not rlp.Encoder", typ)
}
// Default pointer handling.
return bctx.makePtrOp(typ.Elem(), tags)
case *types.Basic:
return bctx.makeBasicOp(typ)
case *types.Struct:
return bctx.makeStructOp(name, typ)
case *types.Slice:
etyp := typ.Elem()
if isByte(etyp) && !bctx.isEncoder(etyp) {
return bctx.makeByteSliceOp(typ), nil
}
return bctx.makeSliceOp(typ)
case *types.Array:
etyp := typ.Elem()
if isByte(etyp) && !bctx.isEncoder(etyp) {
return bctx.makeByteArrayOp(name, typ), nil
}
return nil, fmt.Errorf("unhandled array type: %v", typ)
default:
return nil, fmt.Errorf("unhandled type: %v", typ)
}
}
// generateDecoder generates the DecodeRLP method on 'typ'.
func generateDecoder(ctx *genContext, typ string, op op) []byte {
ctx.resetTemp()
ctx.addImport(pathOfPackageRLP)
result, code := op.genDecode(ctx)
var b bytes.Buffer
fmt.Fprintf(&b, "func (obj *%s) DecodeRLP(dec *rlp.Stream) error {\n", typ)
fmt.Fprint(&b, code)
fmt.Fprintf(&b, " *obj = %s\n", result)
fmt.Fprintf(&b, " return nil\n")
fmt.Fprintf(&b, "}\n")
return b.Bytes()
}
// generateEncoder generates the EncodeRLP method on 'typ'.
func generateEncoder(ctx *genContext, typ string, op op) []byte {
ctx.resetTemp()
ctx.addImport("io")
ctx.addImport(pathOfPackageRLP)
var b bytes.Buffer
fmt.Fprintf(&b, "func (obj *%s) EncodeRLP(_w io.Writer) error {\n", typ)
fmt.Fprintf(&b, " w := rlp.NewEncoderBuffer(_w)\n")
fmt.Fprint(&b, op.genWrite(ctx, "obj"))
fmt.Fprintf(&b, " return w.Flush()\n")
fmt.Fprintf(&b, "}\n")
return b.Bytes()
}
func (bctx *buildContext) generate(typ *types.Named, encoder, decoder bool) ([]byte, error) {
bctx.topType = typ
pkg := typ.Obj().Pkg()
op, err := bctx.makeOp(nil, typ, rlpstruct.Tags{})
if err != nil {
return nil, err
}
var (
ctx = newGenContext(pkg)
encSource []byte
decSource []byte
)
if encoder {
encSource = generateEncoder(ctx, typ.Obj().Name(), op)
}
if decoder {
decSource = generateDecoder(ctx, typ.Obj().Name(), op)
}
var b bytes.Buffer
fmt.Fprintf(&b, "package %s\n\n", pkg.Name())
for _, imp := range ctx.importsList() {
fmt.Fprintf(&b, "import %q\n", imp)
}
if encoder {
fmt.Fprintln(&b)
b.Write(encSource)
}
if decoder {
fmt.Fprintln(&b)
b.Write(decSource)
}
source := b.Bytes()
// fmt.Println(string(source))
return format.Source(source)
}