feat: Waku v2 bridge

Issue #12610

vendor/github.com/ethereum/go-ethereum/rlp/internal/rlpstruct/rlpstruct.go

@@ -0,0 +1,213 @@
+// 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 rlpstruct implements struct processing for RLP encoding/decoding.
+//
+// In particular, this package handles all rules around field filtering,
+// struct tags and nil value determination.
+package rlpstruct
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+)
+
+// Field represents a struct field.
+type Field struct {
+	Name     string
+	Index    int
+	Exported bool
+	Type     Type
+	Tag      string
+}
+
+// Type represents the attributes of a Go type.
+type Type struct {
+	Name      string
+	Kind      reflect.Kind
+	IsEncoder bool  // whether type implements rlp.Encoder
+	IsDecoder bool  // whether type implements rlp.Decoder
+	Elem      *Type // non-nil for Kind values of Ptr, Slice, Array
+}
+
+// DefaultNilValue determines whether a nil pointer to t encodes/decodes
+// as an empty string or empty list.
+func (t Type) DefaultNilValue() NilKind {
+	k := t.Kind
+	if isUint(k) || k == reflect.String || k == reflect.Bool || isByteArray(t) {
+		return NilKindString
+	}
+	return NilKindList
+}
+
+// NilKind is the RLP value encoded in place of nil pointers.
+type NilKind uint8
+
+const (
+	NilKindString NilKind = 0x80
+	NilKindList   NilKind = 0xC0
+)
+
+// Tags represents struct tags.
+type Tags struct {
+	// rlp:"nil" controls whether empty input results in a nil pointer.
+	// nilKind is the kind of empty value allowed for the field.
+	NilKind NilKind
+	NilOK   bool
+
+	// rlp:"optional" allows for a field to be missing in the input list.
+	// If this is set, all subsequent fields must also be optional.
+	Optional bool
+
+	// rlp:"tail" controls whether this field swallows additional list elements. It can
+	// only be set for the last field, which must be of slice type.
+	Tail bool
+
+	// rlp:"-" ignores fields.
+	Ignored bool
+}
+
+// TagError is raised for invalid struct tags.
+type TagError struct {
+	StructType string
+
+	// These are set by this package.
+	Field string
+	Tag   string
+	Err   string
+}
+
+func (e TagError) Error() string {
+	field := "field " + e.Field
+	if e.StructType != "" {
+		field = e.StructType + "." + e.Field
+	}
+	return fmt.Sprintf("rlp: invalid struct tag %q for %s (%s)", e.Tag, field, e.Err)
+}
+
+// ProcessFields filters the given struct fields, returning only fields
+// that should be considered for encoding/decoding.
+func ProcessFields(allFields []Field) ([]Field, []Tags, error) {
+	lastPublic := lastPublicField(allFields)
+
+	// Gather all exported fields and their tags.
+	var fields []Field
+	var tags []Tags
+	for _, field := range allFields {
+		if !field.Exported {
+			continue
+		}
+		ts, err := parseTag(field, lastPublic)
+		if err != nil {
+			return nil, nil, err
+		}
+		if ts.Ignored {
+			continue
+		}
+		fields = append(fields, field)
+		tags = append(tags, ts)
+	}
+
+	// Verify optional field consistency. If any optional field exists,
+	// all fields after it must also be optional. Note: optional + tail
+	// is supported.
+	var anyOptional bool
+	var firstOptionalName string
+	for i, ts := range tags {
+		name := fields[i].Name
+		if ts.Optional || ts.Tail {
+			if !anyOptional {
+				firstOptionalName = name
+			}
+			anyOptional = true
+		} else {
+			if anyOptional {
+				msg := fmt.Sprintf("must be optional because preceding field %q is optional", firstOptionalName)
+				return nil, nil, TagError{Field: name, Err: msg}
+			}
+		}
+	}
+	return fields, tags, nil
+}
+
+func parseTag(field Field, lastPublic int) (Tags, error) {
+	name := field.Name
+	tag := reflect.StructTag(field.Tag)
+	var ts Tags
+	for _, t := range strings.Split(tag.Get("rlp"), ",") {
+		switch t = strings.TrimSpace(t); t {
+		case "":
+			// empty tag is allowed for some reason
+		case "-":
+			ts.Ignored = true
+		case "nil", "nilString", "nilList":
+			ts.NilOK = true
+			if field.Type.Kind != reflect.Ptr {
+				return ts, TagError{Field: name, Tag: t, Err: "field is not a pointer"}
+			}
+			switch t {
+			case "nil":
+				ts.NilKind = field.Type.Elem.DefaultNilValue()
+			case "nilString":
+				ts.NilKind = NilKindString
+			case "nilList":
+				ts.NilKind = NilKindList
+			}
+		case "optional":
+			ts.Optional = true
+			if ts.Tail {
+				return ts, TagError{Field: name, Tag: t, Err: `also has "tail" tag`}
+			}
+		case "tail":
+			ts.Tail = true
+			if field.Index != lastPublic {
+				return ts, TagError{Field: name, Tag: t, Err: "must be on last field"}
+			}
+			if ts.Optional {
+				return ts, TagError{Field: name, Tag: t, Err: `also has "optional" tag`}
+			}
+			if field.Type.Kind != reflect.Slice {
+				return ts, TagError{Field: name, Tag: t, Err: "field type is not slice"}
+			}
+		default:
+			return ts, TagError{Field: name, Tag: t, Err: "unknown tag"}
+		}
+	}
+	return ts, nil
+}
+
+func lastPublicField(fields []Field) int {
+	last := 0
+	for _, f := range fields {
+		if f.Exported {
+			last = f.Index
+		}
+	}
+	return last
+}
+
+func isUint(k reflect.Kind) bool {
+	return k >= reflect.Uint && k <= reflect.Uintptr
+}
+
+func isByte(typ Type) bool {
+	return typ.Kind == reflect.Uint8 && !typ.IsEncoder
+}
+
+func isByteArray(typ Type) bool {
+	return (typ.Kind == reflect.Slice || typ.Kind == reflect.Array) && isByte(*typ.Elem)
+}