ecc876cec0
Removed old unmarshalling of return types: `abi.Call(...).([]byte)`. This is now replaced by a new syntax: ``` var a []byte err := abi.Call(&a, ...) ``` It also addresses a few issues with Bytes and Strings and can also handle both fixed and arbitrary sized byte slices, including strings.
278 lines
8.1 KiB
Go
278 lines
8.1 KiB
Go
// Copyright 2015 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package abi
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import (
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"encoding/json"
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"fmt"
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"io"
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"reflect"
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"strings"
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"github.com/ethereum/go-ethereum/common"
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)
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// Executer is an executer method for performing state executions. It takes one
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// argument which is the input data and expects output data to be returned as
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// multiple 32 byte word length concatenated slice
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type Executer func(datain []byte) []byte
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// The ABI holds information about a contract's context and available
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// invokable methods. It will allow you to type check function calls and
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// packs data accordingly.
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type ABI struct {
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Methods map[string]Method
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Events map[string]Event
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}
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// JSON returns a parsed ABI interface and error if it failed.
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func JSON(reader io.Reader) (ABI, error) {
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dec := json.NewDecoder(reader)
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var abi ABI
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if err := dec.Decode(&abi); err != nil {
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return ABI{}, err
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}
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return abi, nil
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}
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// tests, tests whether the given input would result in a successful
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// call. Checks argument list count and matches input to `input`.
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func (abi ABI) pack(name string, args ...interface{}) ([]byte, error) {
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method := abi.Methods[name]
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var ret []byte
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for i, a := range args {
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input := method.Inputs[i]
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packed, err := input.Type.pack(a)
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if err != nil {
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return nil, fmt.Errorf("`%s` %v", name, err)
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}
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ret = append(ret, packed...)
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}
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return ret, nil
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}
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// Pack the given method name to conform the ABI. Method call's data
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// will consist of method_id, args0, arg1, ... argN. Method id consists
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// of 4 bytes and arguments are all 32 bytes.
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// Method ids are created from the first 4 bytes of the hash of the
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// methods string signature. (signature = baz(uint32,string32))
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func (abi ABI) Pack(name string, args ...interface{}) ([]byte, error) {
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method, exist := abi.Methods[name]
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if !exist {
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return nil, fmt.Errorf("method '%s' not found", name)
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}
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// start with argument count match
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if len(args) != len(method.Inputs) {
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return nil, fmt.Errorf("argument count mismatch: %d for %d", len(args), len(method.Inputs))
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}
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arguments, err := abi.pack(name, args...)
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if err != nil {
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return nil, err
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}
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// Set function id
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packed := abi.Methods[name].Id()
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packed = append(packed, arguments...)
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return packed, nil
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}
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// toGoType parses the input and casts it to the proper type defined by the ABI
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// argument in T.
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func toGoType(i int, t Argument, output []byte) (interface{}, error) {
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index := i * 32
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if index+32 > len(output) {
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return nil, fmt.Errorf("abi: cannot marshal in to go type: length insufficient %d require %d", len(output), index+32)
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}
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// Parse the given index output and check whether we need to read
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// a different offset and length based on the type (i.e. string, bytes)
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var returnOutput []byte
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switch t.Type.T {
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case StringTy, BytesTy: // variable arrays are written at the end of the return bytes
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// parse offset from which we should start reading
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offset := int(common.BytesToBig(output[index : index+32]).Uint64())
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if offset+32 > len(output) {
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return nil, fmt.Errorf("abi: cannot marshal in to go type: length insufficient %d require %d", len(output), offset+32)
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}
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// parse the size up until we should be reading
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size := int(common.BytesToBig(output[offset : offset+32]).Uint64())
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if offset+32+size > len(output) {
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return nil, fmt.Errorf("abi: cannot marshal in to go type: length insufficient %d require %d", len(output), offset+32+size)
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}
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// get the bytes for this return value
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returnOutput = output[offset+32 : offset+32+size]
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default:
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returnOutput = output[index : index+32]
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}
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// cast bytes to abi return type
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switch t.Type.T {
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case IntTy:
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return common.BytesToBig(returnOutput), nil
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case UintTy:
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return common.BytesToBig(returnOutput), nil
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case BoolTy:
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return common.BytesToBig(returnOutput).Uint64() > 0, nil
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case AddressTy:
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return common.BytesToAddress(returnOutput), nil
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case HashTy:
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return common.BytesToHash(returnOutput), nil
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case BytesTy, FixedBytesTy:
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return returnOutput, nil
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case StringTy:
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return string(returnOutput), nil
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}
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return nil, fmt.Errorf("abi: unknown type %v", t.Type.T)
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}
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// Call will unmarshal the output of the call in v. It will return an error if
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// invalid type is given or if the output is too short to conform to the ABI
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// spec.
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//
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// Call supports all of the available types and accepts a struct or an interface
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// slice if the return is a tuple.
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func (abi ABI) Call(executer Executer, v interface{}, name string, args ...interface{}) error {
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callData, err := abi.Pack(name, args...)
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if err != nil {
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return err
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}
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return abi.unmarshal(v, name, executer(callData))
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}
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var interSlice = reflect.TypeOf([]interface{}{})
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// unmarshal output in v according to the abi specification
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func (abi ABI) unmarshal(v interface{}, name string, output []byte) error {
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var method = abi.Methods[name]
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if len(output) == 0 {
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return fmt.Errorf("abi: unmarshalling empty output")
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}
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value := reflect.ValueOf(v).Elem()
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typ := value.Type()
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if len(method.Outputs) > 1 {
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switch value.Kind() {
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// struct will match named return values to the struct's field
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// names
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case reflect.Struct:
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for i := 0; i < len(method.Outputs); i++ {
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marshalledValue, err := toGoType(i, method.Outputs[i], output)
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if err != nil {
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return err
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}
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reflectValue := reflect.ValueOf(marshalledValue)
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for j := 0; j < typ.NumField(); j++ {
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field := typ.Field(j)
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// TODO read tags: `abi:"fieldName"`
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if field.Name == strings.ToUpper(method.Outputs[i].Name[:1])+method.Outputs[i].Name[1:] {
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if field.Type.AssignableTo(reflectValue.Type()) {
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value.Field(j).Set(reflectValue)
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break
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} else {
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return fmt.Errorf("abi: cannot unmarshal %v in to %v", field.Type, reflectValue.Type())
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}
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}
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}
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}
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case reflect.Slice:
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if !value.Type().AssignableTo(interSlice) {
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return fmt.Errorf("abi: cannot marshal tuple in to slice %T (only []interface{} is supported)", v)
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}
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// create a new slice and start appending the unmarshalled
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// values to the new interface slice.
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z := reflect.MakeSlice(typ, 0, len(method.Outputs))
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for i := 0; i < len(method.Outputs); i++ {
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marshalledValue, err := toGoType(i, method.Outputs[i], output)
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if err != nil {
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return err
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}
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z = reflect.Append(z, reflect.ValueOf(marshalledValue))
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}
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value.Set(z)
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default:
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return fmt.Errorf("abi: cannot unmarshal tuple in to %v", typ)
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}
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} else {
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marshalledValue, err := toGoType(0, method.Outputs[0], output)
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if err != nil {
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return err
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}
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reflectValue := reflect.ValueOf(marshalledValue)
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if typ.AssignableTo(reflectValue.Type()) {
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value.Set(reflectValue)
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} else {
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return fmt.Errorf("abi: cannot unmarshal %v in to %v", reflectValue.Type(), value.Type())
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}
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}
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return nil
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}
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func (abi *ABI) UnmarshalJSON(data []byte) error {
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var fields []struct {
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Type string
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Name string
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Const bool
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Indexed bool
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Inputs []Argument
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Outputs []Argument
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}
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if err := json.Unmarshal(data, &fields); err != nil {
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return err
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}
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abi.Methods = make(map[string]Method)
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abi.Events = make(map[string]Event)
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for _, field := range fields {
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switch field.Type {
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// empty defaults to function according to the abi spec
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case "function", "":
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abi.Methods[field.Name] = Method{
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Name: field.Name,
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Const: field.Const,
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Inputs: field.Inputs,
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Outputs: field.Outputs,
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}
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case "event":
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abi.Events[field.Name] = Event{
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Name: field.Name,
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Inputs: field.Inputs,
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}
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}
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}
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return nil
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}
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