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event.go
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event.go
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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 (
"fmt"
"strings"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/crypto"
)
// Event is an event potentially triggered by the EVM's LOG mechanism. The Event
// holds type information (inputs) about the yielded output. Anonymous events
// don't get the signature canonical representation as the first LOG topic.
type Event struct {
// Name is the event name used for internal representation. It's derived from
// the raw name and a suffix will be added in the case of event overloading.
//
// e.g.
// These are two events that have the same name:
// * foo(int,int)
// * foo(uint,uint)
// The event name of the first one will be resolved as foo while the second one
// will be resolved as foo0.
Name string
// RawName is the raw event name parsed from ABI.
RawName string
Anonymous bool
Inputs Arguments
str string
// Sig contains the string signature according to the ABI spec.
// e.g. event foo(uint32 a, int b) = "foo(uint32,int256)"
// Please note that "int" is substitute for its canonical representation "int256"
Sig string
// ID returns the canonical representation of the event's signature used by the
// abi definition to identify event names and types.
ID common.Hash
}
// NewEvent creates a new Event.
// It sanitizes the input arguments to remove unnamed arguments.
// It also precomputes the id, signature and string representation
// of the event.
func NewEvent(name, rawName string, anonymous bool, inputs Arguments) Event {
// sanitize inputs to remove inputs without names
// and precompute string and sig representation.
names := make([]string, len(inputs))
types := make([]string, len(inputs))
for i, input := range inputs {
if input.Name == "" {
inputs[i] = Argument{
Name: fmt.Sprintf("arg%d", i),
Indexed: input.Indexed,
Type: input.Type,
}
} else {
inputs[i] = input
}
// string representation
names[i] = fmt.Sprintf("%v %v", input.Type, inputs[i].Name)
if input.Indexed {
names[i] = fmt.Sprintf("%v indexed %v", input.Type, inputs[i].Name)
}
// sig representation
types[i] = input.Type.String()
}
str := fmt.Sprintf("event %v(%v)", rawName, strings.Join(names, ", "))
sig := fmt.Sprintf("%v(%v)", rawName, strings.Join(types, ","))
id := common.BytesToHash(crypto.Keccak256([]byte(sig)))
return Event{
Name: name,
RawName: rawName,
Anonymous: anonymous,
Inputs: inputs,
str: str,
Sig: sig,
ID: id,
}
}
func (e Event) String() string {
return e.str
}