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- // Copyright 2016 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 abi
- import (
- "errors"
- "fmt"
- "math/big"
- "reflect"
- "strings"
- )
- // ConvertType converts an interface of a runtime type into a interface of the
- // given type
- // e.g. turn
- // var fields []reflect.StructField
- // fields = append(fields, reflect.StructField{
- // Name: "X",
- // Type: reflect.TypeOf(new(big.Int)),
- // Tag: reflect.StructTag("json:\"" + "x" + "\""),
- // }
- // into
- // type TupleT struct { X *big.Int }
- func ConvertType(in interface{}, proto interface{}) interface{} {
- protoType := reflect.TypeOf(proto)
- if reflect.TypeOf(in).ConvertibleTo(protoType) {
- return reflect.ValueOf(in).Convert(protoType).Interface()
- }
- // Use set as a last ditch effort
- if err := set(reflect.ValueOf(proto), reflect.ValueOf(in)); err != nil {
- panic(err)
- }
- return proto
- }
- // indirect recursively dereferences the value until it either gets the value
- // or finds a big.Int
- func indirect(v reflect.Value) reflect.Value {
- if v.Kind() == reflect.Ptr && v.Elem().Type() != reflect.TypeOf(big.Int{}) {
- return indirect(v.Elem())
- }
- return v
- }
- // reflectIntType returns the reflect using the given size and
- // unsignedness.
- func reflectIntType(unsigned bool, size int) reflect.Type {
- if unsigned {
- switch size {
- case 8:
- return reflect.TypeOf(uint8(0))
- case 16:
- return reflect.TypeOf(uint16(0))
- case 32:
- return reflect.TypeOf(uint32(0))
- case 64:
- return reflect.TypeOf(uint64(0))
- }
- }
- switch size {
- case 8:
- return reflect.TypeOf(int8(0))
- case 16:
- return reflect.TypeOf(int16(0))
- case 32:
- return reflect.TypeOf(int32(0))
- case 64:
- return reflect.TypeOf(int64(0))
- }
- return reflect.TypeOf(&big.Int{})
- }
- // mustArrayToByteSlice creates a new byte slice with the exact same size as value
- // and copies the bytes in value to the new slice.
- func mustArrayToByteSlice(value reflect.Value) reflect.Value {
- slice := reflect.MakeSlice(reflect.TypeOf([]byte{}), value.Len(), value.Len())
- reflect.Copy(slice, value)
- return slice
- }
- // set attempts to assign src to dst by either setting, copying or otherwise.
- //
- // set is a bit more lenient when it comes to assignment and doesn't force an as
- // strict ruleset as bare `reflect` does.
- func set(dst, src reflect.Value) error {
- dstType, srcType := dst.Type(), src.Type()
- switch {
- case dstType.Kind() == reflect.Interface && dst.Elem().IsValid():
- return set(dst.Elem(), src)
- case dstType.Kind() == reflect.Ptr && dstType.Elem() != reflect.TypeOf(big.Int{}):
- return set(dst.Elem(), src)
- case srcType.AssignableTo(dstType) && dst.CanSet():
- dst.Set(src)
- case dstType.Kind() == reflect.Slice && srcType.Kind() == reflect.Slice && dst.CanSet():
- return setSlice(dst, src)
- case dstType.Kind() == reflect.Array:
- return setArray(dst, src)
- case dstType.Kind() == reflect.Struct:
- return setStruct(dst, src)
- default:
- return fmt.Errorf("abi: cannot unmarshal %v in to %v", src.Type(), dst.Type())
- }
- return nil
- }
- // setSlice attempts to assign src to dst when slices are not assignable by default
- // e.g. src: [][]byte -> dst: [][15]byte
- // setSlice ignores if we cannot copy all of src' elements.
- func setSlice(dst, src reflect.Value) error {
- slice := reflect.MakeSlice(dst.Type(), src.Len(), src.Len())
- for i := 0; i < src.Len(); i++ {
- if src.Index(i).Kind() == reflect.Struct {
- if err := set(slice.Index(i), src.Index(i)); err != nil {
- return err
- }
- } else {
- // e.g. [][32]uint8 to []common.Hash
- if err := set(slice.Index(i), src.Index(i)); err != nil {
- return err
- }
- }
- }
- if dst.CanSet() {
- dst.Set(slice)
- return nil
- }
- return errors.New("Cannot set slice, destination not settable")
- }
- func setArray(dst, src reflect.Value) error {
- if src.Kind() == reflect.Ptr {
- return set(dst, indirect(src))
- }
- array := reflect.New(dst.Type()).Elem()
- min := src.Len()
- if src.Len() > dst.Len() {
- min = dst.Len()
- }
- for i := 0; i < min; i++ {
- if err := set(array.Index(i), src.Index(i)); err != nil {
- return err
- }
- }
- if dst.CanSet() {
- dst.Set(array)
- return nil
- }
- return errors.New("Cannot set array, destination not settable")
- }
- func setStruct(dst, src reflect.Value) error {
- for i := 0; i < src.NumField(); i++ {
- srcField := src.Field(i)
- dstField := dst.Field(i)
- if !dstField.IsValid() || !srcField.IsValid() {
- return fmt.Errorf("Could not find src field: %v value: %v in destination", srcField.Type().Name(), srcField)
- }
- if err := set(dstField, srcField); err != nil {
- return err
- }
- }
- return nil
- }
- // mapArgNamesToStructFields maps a slice of argument names to struct fields.
- // first round: for each Exportable field that contains a `abi:""` tag
- // and this field name exists in the given argument name list, pair them together.
- // second round: for each argument name that has not been already linked,
- // find what variable is expected to be mapped into, if it exists and has not been
- // used, pair them.
- // Note this function assumes the given value is a struct value.
- func mapArgNamesToStructFields(argNames []string, value reflect.Value) (map[string]string, error) {
- typ := value.Type()
- abi2struct := make(map[string]string)
- struct2abi := make(map[string]string)
- // first round ~~~
- for i := 0; i < typ.NumField(); i++ {
- structFieldName := typ.Field(i).Name
- // skip private struct fields.
- if structFieldName[:1] != strings.ToUpper(structFieldName[:1]) {
- continue
- }
- // skip fields that have no abi:"" tag.
- tagName, ok := typ.Field(i).Tag.Lookup("abi")
- if !ok {
- continue
- }
- // check if tag is empty.
- if tagName == "" {
- return nil, fmt.Errorf("struct: abi tag in '%s' is empty", structFieldName)
- }
- // check which argument field matches with the abi tag.
- found := false
- for _, arg := range argNames {
- if arg == tagName {
- if abi2struct[arg] != "" {
- return nil, fmt.Errorf("struct: abi tag in '%s' already mapped", structFieldName)
- }
- // pair them
- abi2struct[arg] = structFieldName
- struct2abi[structFieldName] = arg
- found = true
- }
- }
- // check if this tag has been mapped.
- if !found {
- return nil, fmt.Errorf("struct: abi tag '%s' defined but not found in abi", tagName)
- }
- }
- // second round ~~~
- for _, argName := range argNames {
- structFieldName := ToCamelCase(argName)
- if structFieldName == "" {
- return nil, fmt.Errorf("abi: purely underscored output cannot unpack to struct")
- }
- // this abi has already been paired, skip it... unless there exists another, yet unassigned
- // struct field with the same field name. If so, raise an error:
- // abi: [ { "name": "value" } ]
- // struct { Value *big.Int , Value1 *big.Int `abi:"value"`}
- if abi2struct[argName] != "" {
- if abi2struct[argName] != structFieldName &&
- struct2abi[structFieldName] == "" &&
- value.FieldByName(structFieldName).IsValid() {
- return nil, fmt.Errorf("abi: multiple variables maps to the same abi field '%s'", argName)
- }
- continue
- }
- // return an error if this struct field has already been paired.
- if struct2abi[structFieldName] != "" {
- return nil, fmt.Errorf("abi: multiple outputs mapping to the same struct field '%s'", structFieldName)
- }
- if value.FieldByName(structFieldName).IsValid() {
- // pair them
- abi2struct[argName] = structFieldName
- struct2abi[structFieldName] = argName
- } else {
- // not paired, but annotate as used, to detect cases like
- // abi : [ { "name": "value" }, { "name": "_value" } ]
- // struct { Value *big.Int }
- struct2abi[structFieldName] = argName
- }
- }
- return abi2struct, nil
- }
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