// 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 bind generates Ethereum contract Go bindings.
package bind
import (
"bytes"
"fmt"
"sort"
"strings"
"github.com/ethereum/go-ethereum/accounts/abi"
"golang.org/x/tools/imports"
)
// Bind generates a Go wrapper around a contract ABI. This wrapper isn't meant
// to be used as is in client code, but rather as an intermediate struct which
// enforces compile time type safety and naming convention opposed to having to
// manually maintain hard coded strings that break on runtime.
func Bind(abijson string, bytecode string, pkg string, kind string) (string, error) {
// Parse the actual ABI to generate the binding for
abi, err := abi.JSON(strings.NewReader(abijson))
if err != nil {
return "", err
}
// Generate the contract type, fields and methods
code := new(bytes.Buffer)
kind = strings.ToUpper(kind[:1]) + kind[1:]
fmt.Fprintf(code, "%s\n", bindContract(kind, strings.TrimSpace(abijson)))
fmt.Fprintf(code, "%s\n", bindConstructor(kind, strings.TrimSpace(bytecode), abi.Constructor))
methods := make([]string, 0, len(abi.Methods))
for name, _ := range abi.Methods {
methods = append(methods, name)
}
sort.Strings(methods)
for _, method := range methods {
fmt.Fprintf(code, "%s\n", bindMethod(kind, abi.Methods[method]))
}
// Format the code with goimports and return
buffer := new(bytes.Buffer)
fmt.Fprintf(buffer, "// This file is an automatically generated Go binding based on the contract ABI\n")
fmt.Fprintf(buffer, "// defined in %sABI. Do not modify as any change will likely be lost!\n\n", kind)
fmt.Fprintf(buffer, "package %s\n\n", pkg)
fmt.Fprintf(buffer, "%s\n\n", string(code.Bytes()))
blob, err := imports.Process("", buffer.Bytes(), nil)
if err != nil {
return "", fmt.Errorf("%v\n%s", err, code)
}
return string(blob), nil
}
// bindContract generates the basic wrapper code for interacting with an Ethereum
// contract via the abi package. All contract methods will call into the generic
// ones generated here.
func bindContract(kind string, abijson string) string {
code := ""
// Generate the hard coded ABI used for Ethereum interaction
code += fmt.Sprintf("// Ethereum ABI used to generate the binding from.\nconst %sABI = `%s`\n\n", kind, abijson)
// Generate the high level contract wrapper types
code += fmt.Sprintf("// %s is an auto generated Go binding around an Ethereum contract.\n", kind)
code += fmt.Sprintf("type %s struct {\n", kind)
code += fmt.Sprintf(" %sCaller // Read-only binding to the contract\n", kind)
code += fmt.Sprintf(" %sTransactor // Write-only binding to the contract\n", kind)
code += fmt.Sprintf("}\n\n")
code += fmt.Sprintf("// %sCaller is an auto generated read-only Go binding around an Ethereum contract.\n", kind)
code += fmt.Sprintf("type %sCaller struct {\n", kind)
code += fmt.Sprintf(" contract *bind.BoundContract // Generic contract wrapper for the low level calls\n")
code += fmt.Sprintf("}\n\n")
code += fmt.Sprintf("// %sTransactor is an auto generated write-only Go binding around an Ethereum contract.\n", kind)
code += fmt.Sprintf("type %sTransactor struct {\n", kind)
code += fmt.Sprintf(" contract *bind.BoundContract // Generic contract wrapper for the low level calls\n")
code += fmt.Sprintf("}\n\n")
// Generate the high level contract session wrapper types
code += fmt.Sprintf("// %sSession is an auto generated Go binding around an Ethereum contract,\n// with pre-set call and transact options.\n", kind)
code += fmt.Sprintf("type %sSession struct {\n", kind)
code += fmt.Sprintf(" Contract *%s // Generic contract binding to set the session for\n", kind)
code += fmt.Sprintf(" CallOpts bind.CallOpts // Call options to use throughout this session\n")
code += fmt.Sprintf(" TransactOpts bind.TransactOpts // Transaction auth options to use throughout this session\n")
code += fmt.Sprintf("}\n\n")
code += fmt.Sprintf("// %sCallerSession is an auto generated read-only Go binding around an Ethereum contract,\n// with pre-set call options.\n", kind)
code += fmt.Sprintf("type %sCallerSession struct {\n", kind)
code += fmt.Sprintf(" Contract *%sCaller // Generic contract caller binding to set the session for\n", kind)
code += fmt.Sprintf(" CallOpts bind.CallOpts // Call options to use throughout this session\n")
code += fmt.Sprintf("}\n\n")
code += fmt.Sprintf("// %sTransactorSession is an auto generated write-only Go binding around an Ethereum contract,\n// with pre-set transact options.\n", kind)
code += fmt.Sprintf("type %sTransactorSession struct {\n", kind)
code += fmt.Sprintf(" Contract *%sTransactor // Generic contract transactor binding to set the session for\n", kind)
code += fmt.Sprintf(" TransactOpts bind.TransactOpts // Transaction auth options to use throughout this session\n")
code += fmt.Sprintf("}\n\n")
// Generate the constructor to create a bound contract
code += fmt.Sprintf("// New%s creates a new instance of %s, bound to a specific deployed contract.\n", kind, kind)
code += fmt.Sprintf("func New%s(address common.Address, backend bind.ContractBackend) (*%s, error) {\n", kind, kind)
code += fmt.Sprintf(" contract, err := bind%s(address, backend.(bind.ContractCaller), backend.(bind.ContractTransactor))\n", kind)
code += fmt.Sprintf(" if err != nil {\n")
code += fmt.Sprintf(" return nil, err\n")
code += fmt.Sprintf(" }\n")
code += fmt.Sprintf(" return &%s{%sCaller: %sCaller{contract: contract}, %sTransactor: %sTransactor{contract: contract}}, nil\n", kind, kind, kind, kind, kind)
code += fmt.Sprintf("}\n\n")
code += fmt.Sprintf("// New%sCaller creates a new read-only instance of %s, bound to a specific deployed contract.\n", kind, kind)
code += fmt.Sprintf("func New%sCaller(address common.Address, caller bind.ContractCaller) (*%sCaller, error) {\n", kind, kind)
code += fmt.Sprintf(" contract, err := bind%s(address, caller, nil)\n", kind)
code += fmt.Sprintf(" if err != nil {\n")
code += fmt.Sprintf(" return nil, err\n")
code += fmt.Sprintf(" }\n")
code += fmt.Sprintf(" return &%sCaller{contract: contract}, nil\n", kind)
code += fmt.Sprintf("}\n\n")
code += fmt.Sprintf("// New%sTransactor creates a new write-only instance of %s, bound to a specific deployed contract.\n", kind, kind)
code += fmt.Sprintf("func New%sTransactor(address common.Address, transactor bind.ContractTransactor) (*%sTransactor, error) {\n", kind, kind)
code += fmt.Sprintf(" contract, err := bind%s(address, nil, transactor)\n", kind)
code += fmt.Sprintf(" if err != nil {\n")
code += fmt.Sprintf(" return nil, err\n")
code += fmt.Sprintf(" }\n")
code += fmt.Sprintf(" return &%sTransactor{contract: contract}, nil\n", kind)
code += fmt.Sprintf("}\n\n")
code += fmt.Sprintf("// bind%s binds a generic wrapper to an already deployed contract.\n", kind)
code += fmt.Sprintf("func bind%s(address common.Address, caller bind.ContractCaller, transactor bind.ContractTransactor) (*bind.BoundContract, error) {\n", kind)
code += fmt.Sprintf(" parsed, err := abi.JSON(strings.NewReader(%sABI))\n", kind)
code += fmt.Sprintf(" if err != nil {\n")
code += fmt.Sprintf(" return nil, err\n")
code += fmt.Sprintf(" }\n")
code += fmt.Sprintf(" return bind.NewBoundContract(address, parsed, caller, transactor), nil\n")
code += fmt.Sprintf("}")
return code
}
// bindConstructor
func bindConstructor(kind string, bytecode string, constructor abi.Method) string {
// If no byte code was supplied, we cannot deploy
if bytecode == "" {
return ""
}
// Otherwise store the bytecode into a global constant
code := fmt.Sprintf("// Ethereum VM bytecode used for deploying new contracts.\nconst %sBin = `%s`\n\n", kind, bytecode)
// Generate the argument list for the constructor
args := make([]string, 0, len(constructor.Inputs))
for i, arg := range constructor.Inputs {
param := arg.Name
if param == "" {
param = fmt.Sprintf("arg%d", i)
}
args = append(args, fmt.Sprintf("%s %s", param, bindType(arg.Type)))
}
arglist := ""
if len(args) > 0 {
arglist = "," + strings.Join(args, ",")
}
// Generate the cal parameter list for the dpeloyer
params := make([]string, len(args))
for i, param := range args {
params[i] = strings.Split(param, " ")[0]
}
paramlist := ""
if len(params) > 0 {
paramlist = "," + strings.Join(params, ",")
}
// And generate the global deployment function
code += fmt.Sprintf("// Deploy%s deploys a new contract, binding an instance of %s to it.\n", kind, kind)
code += fmt.Sprintf("func Deploy%s(auth *bind.TransactOpts, backend bind.ContractBackend %s) (common.Address, *types.Transaction, *%s, error) {\n", kind, arglist, kind)
code += fmt.Sprintf(" parsed, err := abi.JSON(strings.NewReader(%sABI))\n", kind)
code += fmt.Sprintf(" if err != nil {\n")
code += fmt.Sprintf(" return common.Address{}, nil, nil, err\n")
code += fmt.Sprintf(" }\n")
code += fmt.Sprintf(" address, tx, contract, err := bind.DeployContract(auth, parsed, common.FromHex(%sBin), backend %s)\n", kind, paramlist)
code += fmt.Sprintf(" if err != nil {\n")
code += fmt.Sprintf(" return common.Address{}, nil, nil, err\n")
code += fmt.Sprintf(" }\n")
code += fmt.Sprintf(" return address, tx, &%s{%sCaller: %sCaller{contract: contract}, %sTransactor: %sTransactor{contract: contract}}, nil\n", kind, kind, kind, kind, kind)
code += fmt.Sprintf("}\n\n")
return code
}
// bindMethod
func bindMethod(kind string, method abi.Method) string {
var (
name = strings.ToUpper(method.Name[:1]) + method.Name[1:]
prologue = new(bytes.Buffer)
)
// Generate the argument and return list for the function
args := make([]string, 0, len(method.Inputs))
for i, arg := range method.Inputs {
param := arg.Name
if param == "" {
param = fmt.Sprintf("arg%d", i)
}
args = append(args, fmt.Sprintf("%s %s", param, bindType(arg.Type)))
}
returns, _ := bindReturn(prologue, name, method.Outputs)
// Generate the docs to help with coding against the binding
callTypeDoc := "free data retrieval call"
if !method.Const {
callTypeDoc = "paid mutator transaction"
}
docs := fmt.Sprintf("// %s is a %s binding the contract method 0x%x.\n", name, callTypeDoc, method.Id())
docs += fmt.Sprintf("// \n")
docs += fmt.Sprintf("// Solidity: %s", strings.TrimPrefix(method.String(), "function "))
// Generate the passthrough argument list for sessions
params := make([]string, len(args))
for i, param := range args {
params[i] = strings.Split(param, " ")[0]
}
sessargs := ""
if len(params) > 0 {
sessargs = "," + strings.Join(params, ",")
}
// Generate the method itself for both the read/write version and the combo too
code := fmt.Sprintf("%s\n", prologue)
if method.Const {
// Create the main call implementation
callargs := append([]string{"opts *bind.CallOpts"}, args...)
code += fmt.Sprintf("%s\n", docs)
code += fmt.Sprintf("func (_%s *%sCaller) %s(%s) (%s) {\n", kind, kind, name, strings.Join(callargs, ","), strings.Join(returns, ","))
code += fmt.Sprintf(" %s\n", bindCallBody(kind, method.Name, callargs, returns))
code += fmt.Sprintf("}\n\n")
// Create the wrapping session call implementation
code += fmt.Sprintf("%s\n", docs)
code += fmt.Sprintf("func (_%s *%sSession) %s(%s) (%s) {\n", kind, kind, name, strings.Join(args, ","), strings.Join(returns, ","))
code += fmt.Sprintf(" return _%s.Contract.%s(&_%s.CallOpts %s)\n", kind, name, kind, sessargs)
code += fmt.Sprintf("}\n\n")
code += fmt.Sprintf("%s\n", docs)
code += fmt.Sprintf("func (_%s *%sCallerSession) %s(%s) (%s) {\n", kind, kind, name, strings.Join(args, ","), strings.Join(returns, ","))
code += fmt.Sprintf(" return _%s.Contract.%s(&_%s.CallOpts %s)\n", kind, name, kind, sessargs)
code += fmt.Sprintf("}\n\n")
} else {
// Create the main transaction implementation
txargs := append([]string{"opts *bind.TransactOpts"}, args...)
code += fmt.Sprintf("%s\n", docs)
code += fmt.Sprintf("func (_%s *%sTransactor) %s(%s) (*types.Transaction, error) {\n", kind, kind, name, strings.Join(txargs, ","))
code += fmt.Sprintf(" %s\n", bindTransactionBody(kind, method.Name, txargs))
code += fmt.Sprintf("}\n\n")
// Create the wrapping session call implementation
code += fmt.Sprintf("%s\n", docs)
code += fmt.Sprintf("func (_%s *%sSession) %s(%s) (*types.Transaction, error) {\n", kind, kind, name, strings.Join(args, ","))
code += fmt.Sprintf(" return _%s.Contract.%s(&_%s.TransactOpts %s)\n", kind, name, kind, sessargs)
code += fmt.Sprintf("}\n\n")
code += fmt.Sprintf("%s\n", docs)
code += fmt.Sprintf("func (_%s *%sTransactorSession) %s(%s) (*types.Transaction, error) {\n", kind, kind, name, strings.Join(args, ","))
code += fmt.Sprintf(" return _%s.Contract.%s(&_%s.TransactOpts %s)\n", kind, name, kind, sessargs)
code += fmt.Sprintf("}\n\n")
}
return code
}
// bindType converts a Solidity type to a Go one. Since there is no clear mapping
// from all Solidity types to Go ones (e.g. uint17), those that cannot be exactly
// mapped will use an upscaled type (e.g. *big.Int).
func bindType(kind abi.Type) string {
stringKind := kind.String()
switch {
case stringKind == "address":
return "common.Address"
case stringKind == "hash":
return "common.Hash"
case strings.HasPrefix(stringKind, "bytes"):
if stringKind == "bytes" {
return "[]byte"
}
return fmt.Sprintf("[%s]byte", stringKind[5:])
case strings.HasPrefix(stringKind, "int"):
switch stringKind[:3] {
case "8", "16", "32", "64":
return stringKind
}
return "*big.Int"
case strings.HasPrefix(stringKind, "uint"):
switch stringKind[:4] {
case "8", "16", "32", "64":
return stringKind
}
return "*big.Int"
default:
return stringKind
}
}
// bindReturn creates the list of return parameters for a method invocation. If
// all the fields of the return type are named, and there is more than one value
// being returned, the returns are wrapped in a result struct.
func bindReturn(prologue *bytes.Buffer, method string, outputs []abi.Argument) ([]string, string) {
// Generate the anonymous return list for when a struct is not needed/possible
var (
returns = make([]string, 0, len(outputs)+1)
anonymous = false
)
for _, ret := range outputs {
returns = append(returns, bindType(ret.Type))
if ret.Name == "" {
anonymous = true
}
}
if anonymous || len(returns) < 2 {
returns = append(returns, "error")
return returns, ""
}
// If the returns are named and numerous, wrap in a result struct
wrapper, impl := bindReturnStruct(method, outputs)
prologue.WriteString(impl + "\n")
return []string{"*" + wrapper, "error"}, wrapper
}
// bindReturnStruct creates a Go structure with the specified fields to be used
// as the return type from a method call.
func bindReturnStruct(method string, returns []abi.Argument) (string, string) {
fields := make([]string, 0, len(returns))
for _, ret := range returns {
fields = append(fields, fmt.Sprintf("%s %s", strings.ToUpper(ret.Name[:1])+ret.Name[1:], bindType(ret.Type)))
}
kind := fmt.Sprintf("%sResult", method)
docs := fmt.Sprintf("// %s is the result of the %s invocation.", kind, method)
return kind, fmt.Sprintf("%s\ntype %s struct {\n%s\n}", docs, kind, strings.Join(fields, "\n"))
}
// bindCallBody creates the Go code to declare a batch of return values, invoke
// an Ethereum method call with the requested parameters, parse the binary output
// into the return values and return them.
func bindCallBody(kind string, method string, params []string, returns []string) string {
body := ""
// Allocate memory for each of the return values
rets := make([]string, 0, len(returns)-1)
if len(returns) > 1 {
body += "var ("
for i, kind := range returns[:len(returns)-1] { // Omit the final error
name := fmt.Sprintf("ret%d", i)
rets = append(rets, name)
body += fmt.Sprintf("%s = new(%s)\n", name, kind)
}
body += ")\n"
}
// Assemble a single collector variable for the result ABI initialization
result := strings.Join(rets, ",")
if len(returns) > 2 {
result = "[]interface{}{" + result + "}"
}
// Extract the parameter list into a flat variable name list
inputs := make([]string, len(params)-1) // Omit the call options
for i, param := range params[1:] {
inputs[i] = strings.Split(param, " ")[0]
}
input := ""
if len(inputs) > 0 {
input = "," + strings.Join(inputs, ",")
}
// Request executing the contract call and return the results with the errors
body += fmt.Sprintf("err := _%s.contract.Call(opts, %s, \"%s\" %s)\n", kind, result, method, input)
outs := make([]string, 0, len(returns))
for _, ret := range rets { // Handle th final error separately
outs = append(outs, "*"+ret)
}
outs = append(outs, "err")
body += fmt.Sprintf("return %s", strings.Join(outs, ","))
return body
}
// bindTransactionBody creates the Go code to invoke an Ethereum transaction call
// with the requested parameters, and return the assembled transaction object.
func bindTransactionBody(kind string, method string, params []string) string {
// Extract the parameter list into a flat variable name list
inputs := make([]string, len(params)-1) // Omit the auth options
for i, param := range params[1:] {
inputs[i] = strings.Split(param, " ")[0]
}
input := ""
if len(inputs) > 0 {
input = "," + strings.Join(inputs, ",")
}
// Request executing the contract call and return the results with the errors
return fmt.Sprintf("return _%s.contract.Transact(opts, \"%s\" %s)", kind, method, input)
}
