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path: root/accounts/abi/bind/topics.go
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// Copyright 2018 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 bind

import (
    "errors"
    "fmt"
    "math/big"
    "reflect"

    "github.com/ethereum/go-ethereum/accounts/abi"
    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/crypto"
)

// makeTopics converts a filter query argument list into a filter topic set.
func makeTopics(query ...[]interface{}) ([][]common.Hash, error) {
    topics := make([][]common.Hash, len(query))
    for i, filter := range query {
        for _, rule := range filter {
            var topic common.Hash

            // Try to generate the topic based on simple types
            switch rule := rule.(type) {
            case common.Hash:
                copy(topic[:], rule[:])
            case common.Address:
                copy(topic[common.HashLength-common.AddressLength:], rule[:])
            case *big.Int:
                blob := rule.Bytes()
                copy(topic[common.HashLength-len(blob):], blob)
            case bool:
                if rule {
                    topic[common.HashLength-1] = 1
                }
            case int8:
                blob := big.NewInt(int64(rule)).Bytes()
                copy(topic[common.HashLength-len(blob):], blob)
            case int16:
                blob := big.NewInt(int64(rule)).Bytes()
                copy(topic[common.HashLength-len(blob):], blob)
            case int32:
                blob := big.NewInt(int64(rule)).Bytes()
                copy(topic[common.HashLength-len(blob):], blob)
            case int64:
                blob := big.NewInt(rule).Bytes()
                copy(topic[common.HashLength-len(blob):], blob)
            case uint8:
                blob := new(big.Int).SetUint64(uint64(rule)).Bytes()
                copy(topic[common.HashLength-len(blob):], blob)
            case uint16:
                blob := new(big.Int).SetUint64(uint64(rule)).Bytes()
                copy(topic[common.HashLength-len(blob):], blob)
            case uint32:
                blob := new(big.Int).SetUint64(uint64(rule)).Bytes()
                copy(topic[common.HashLength-len(blob):], blob)
            case uint64:
                blob := new(big.Int).SetUint64(rule).Bytes()
                copy(topic[common.HashLength-len(blob):], blob)
            case string:
                hash := crypto.Keccak256Hash([]byte(rule))
                copy(topic[:], hash[:])
            case []byte:
                hash := crypto.Keccak256Hash(rule)
                copy(topic[:], hash[:])

            default:
                // Attempt to generate the topic from funky types
                val := reflect.ValueOf(rule)

                switch {
                case val.Kind() == reflect.Array && reflect.TypeOf(rule).Elem().Kind() == reflect.Uint8:
                    reflect.Copy(reflect.ValueOf(topic[common.HashLength-val.Len():]), val)

                default:
                    return nil, fmt.Errorf("unsupported indexed type: %T", rule)
                }
            }
            topics[i] = append(topics[i], topic)
        }
    }
    return topics, nil
}

// Big batch of reflect types for topic reconstruction.
var (
    reflectHash    = reflect.TypeOf(common.Hash{})
    reflectAddress = reflect.TypeOf(common.Address{})
    reflectBigInt  = reflect.TypeOf(new(big.Int))
)

// parseTopics converts the indexed topic fields into actual log field values.
//
// Note, dynamic types cannot be reconstructed since they get mapped to Keccak256
// hashes as the topic value!
func parseTopics(out interface{}, fields abi.Arguments, topics []common.Hash) error {
    // Sanity check that the fields and topics match up
    if len(fields) != len(topics) {
        return errors.New("topic/field count mismatch")
    }
    // Iterate over all the fields and reconstruct them from topics
    for _, arg := range fields {
        if !arg.Indexed {
            return errors.New("non-indexed field in topic reconstruction")
        }
        field := reflect.ValueOf(out).Elem().FieldByName(capitalise(arg.Name))

        // Try to parse the topic back into the fields based on primitive types
        switch field.Kind() {
        case reflect.Bool:
            if topics[0][common.HashLength-1] == 1 {
                field.Set(reflect.ValueOf(true))
            }
        case reflect.Int8:
            num := new(big.Int).SetBytes(topics[0][:])
            field.Set(reflect.ValueOf(int8(num.Int64())))

        case reflect.Int16:
            num := new(big.Int).SetBytes(topics[0][:])
            field.Set(reflect.ValueOf(int16(num.Int64())))

        case reflect.Int32:
            num := new(big.Int).SetBytes(topics[0][:])
            field.Set(reflect.ValueOf(int32(num.Int64())))

        case reflect.Int64:
            num := new(big.Int).SetBytes(topics[0][:])
            field.Set(reflect.ValueOf(num.Int64()))

        case reflect.Uint8:
            num := new(big.Int).SetBytes(topics[0][:])
            field.Set(reflect.ValueOf(uint8(num.Uint64())))

        case reflect.Uint16:
            num := new(big.Int).SetBytes(topics[0][:])
            field.Set(reflect.ValueOf(uint16(num.Uint64())))

        case reflect.Uint32:
            num := new(big.Int).SetBytes(topics[0][:])
            field.Set(reflect.ValueOf(uint32(num.Uint64())))

        case reflect.Uint64:
            num := new(big.Int).SetBytes(topics[0][:])
            field.Set(reflect.ValueOf(num.Uint64()))

        default:
            // Ran out of plain primitive types, try custom types
            switch field.Type() {
            case reflectHash: // Also covers all dynamic types
                field.Set(reflect.ValueOf(topics[0]))

            case reflectAddress:
                var addr common.Address
                copy(addr[:], topics[0][common.HashLength-common.AddressLength:])
                field.Set(reflect.ValueOf(addr))

            case reflectBigInt:
                num := new(big.Int).SetBytes(topics[0][:])
                field.Set(reflect.ValueOf(num))

            default:
                // Ran out of custom types, try the crazies
                switch {
                case arg.Type.T == abi.FixedBytesTy:
                    reflect.Copy(field, reflect.ValueOf(topics[0][common.HashLength-arg.Type.Size:]))

                default:
                    return fmt.Errorf("unsupported indexed type: %v", arg.Type)
                }
            }
        }
        topics = topics[1:]
    }
    return nil
}