go-ethereum/rlp/rlpgen/main.go

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rlp/rlpgen: RLP encoder code generator (#24251) This change adds a code generator tool for creating EncodeRLP method implementations. The generated methods will behave identically to the reflect-based encoder, but run faster because there is no reflection overhead. Package rlp now provides the EncoderBuffer type for incremental encoding. This is used by generated code, but the new methods can also be useful for hand-written encoders. There is also experimental support for generating DecodeRLP, and some new methods have been added to the existing Stream type to support this. Creating decoders with rlpgen is not recommended at this time because the generated methods create very poor error reporting. More detail about package rlp changes: * rlp: externalize struct field processing / validation This adds a new package, rlp/internal/rlpstruct, in preparation for the RLP encoder generator. I think the struct field rules are subtle enough to warrant extracting this into their own package, even though it means that a bunch of adapter code is needed for converting to/from rlpstruct.Type. * rlp: add more decoder methods (for rlpgen) This adds new methods on rlp.Stream: - Uint64, Uint32, Uint16, Uint8, BigInt - ReadBytes for decoding into []byte - MoreDataInList - useful for optional list elements * rlp: expose encoder buffer (for rlpgen) This exposes the internal encoder buffer type for use in EncodeRLP implementations. The new EncoderBuffer type is a sort-of 'opaque handle' for a pointer to encBuffer. It is implemented this way to ensure the global encBuffer pool is handled correctly.
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// Copyright 2021 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"
"errors"
"flag"
"fmt"
"go/types"
"os"
"golang.org/x/tools/go/packages"
)
const pathOfPackageRLP = "github.com/ethereum/go-ethereum/rlp"
func main() {
var (
pkgdir = flag.String("dir", ".", "input package")
output = flag.String("out", "-", "output file (default is stdout)")
genEncoder = flag.Bool("encoder", true, "generate EncodeRLP?")
genDecoder = flag.Bool("decoder", false, "generate DecodeRLP?")
typename = flag.String("type", "", "type to generate methods for")
)
flag.Parse()
cfg := Config{
Dir: *pkgdir,
Type: *typename,
GenerateEncoder: *genEncoder,
GenerateDecoder: *genDecoder,
}
code, err := cfg.process()
if err != nil {
fatal(err)
}
if *output == "-" {
os.Stdout.Write(code)
} else if err := os.WriteFile(*output, code, 0644); err != nil {
rlp/rlpgen: RLP encoder code generator (#24251) This change adds a code generator tool for creating EncodeRLP method implementations. The generated methods will behave identically to the reflect-based encoder, but run faster because there is no reflection overhead. Package rlp now provides the EncoderBuffer type for incremental encoding. This is used by generated code, but the new methods can also be useful for hand-written encoders. There is also experimental support for generating DecodeRLP, and some new methods have been added to the existing Stream type to support this. Creating decoders with rlpgen is not recommended at this time because the generated methods create very poor error reporting. More detail about package rlp changes: * rlp: externalize struct field processing / validation This adds a new package, rlp/internal/rlpstruct, in preparation for the RLP encoder generator. I think the struct field rules are subtle enough to warrant extracting this into their own package, even though it means that a bunch of adapter code is needed for converting to/from rlpstruct.Type. * rlp: add more decoder methods (for rlpgen) This adds new methods on rlp.Stream: - Uint64, Uint32, Uint16, Uint8, BigInt - ReadBytes for decoding into []byte - MoreDataInList - useful for optional list elements * rlp: expose encoder buffer (for rlpgen) This exposes the internal encoder buffer type for use in EncodeRLP implementations. The new EncoderBuffer type is a sort-of 'opaque handle' for a pointer to encBuffer. It is implemented this way to ensure the global encBuffer pool is handled correctly.
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fatal(err)
}
}
func fatal(args ...interface{}) {
fmt.Fprintln(os.Stderr, args...)
os.Exit(1)
}
type Config struct {
Dir string // input package directory
Type string
GenerateEncoder bool
GenerateDecoder bool
}
// process generates the Go code.
func (cfg *Config) process() (code []byte, err error) {
// Load packages.
pcfg := &packages.Config{
Mode: packages.NeedName | packages.NeedTypes | packages.NeedImports | packages.NeedDeps,
Dir: cfg.Dir,
BuildFlags: []string{"-tags", "norlpgen"},
}
ps, err := packages.Load(pcfg, pathOfPackageRLP, ".")
if err != nil {
return nil, err
}
if len(ps) == 0 {
return nil, fmt.Errorf("no Go package found in %s", cfg.Dir)
}
packages.PrintErrors(ps)
// Find the packages that were loaded.
var (
pkg *types.Package
packageRLP *types.Package
)
for _, p := range ps {
if len(p.Errors) > 0 {
return nil, fmt.Errorf("package %s has errors", p.PkgPath)
}
if p.PkgPath == pathOfPackageRLP {
packageRLP = p.Types
} else {
pkg = p.Types
}
}
bctx := newBuildContext(packageRLP)
// Find the type and generate.
typ, err := lookupStructType(pkg.Scope(), cfg.Type)
if err != nil {
return nil, fmt.Errorf("can't find %s in %s: %v", typ, pkg, err)
}
code, err = bctx.generate(typ, cfg.GenerateEncoder, cfg.GenerateDecoder)
if err != nil {
return nil, err
}
// Add build comments.
// This is done here to avoid processing these lines with gofmt.
var header bytes.Buffer
fmt.Fprint(&header, "// Code generated by rlpgen. DO NOT EDIT.\n\n")
fmt.Fprint(&header, "//go:build !norlpgen\n")
fmt.Fprint(&header, "// +build !norlpgen\n\n")
return append(header.Bytes(), code...), nil
}
func lookupStructType(scope *types.Scope, name string) (*types.Named, error) {
typ, err := lookupType(scope, name)
if err != nil {
return nil, err
}
_, ok := typ.Underlying().(*types.Struct)
if !ok {
return nil, errors.New("not a struct type")
}
return typ, nil
}
func lookupType(scope *types.Scope, name string) (*types.Named, error) {
obj := scope.Lookup(name)
if obj == nil {
return nil, errors.New("no such identifier")
}
typ, ok := obj.(*types.TypeName)
if !ok {
return nil, errors.New("not a type")
}
return typ.Type().(*types.Named), nil
}