path: root/accounts/abi/bind/bind.go

// 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.
//
// Detailed usage document and tutorial available on the go-ethereum Wiki page:
// https://github.com/ethereum/go-ethereum/wiki/Native-DApps:-Go-bindings-to-Ethereum-contracts
package bind

import (
    "bytes"
    "fmt"
    "regexp"
    "strings"
    "text/template"
    "unicode"

    "github.com/ethereum/go-ethereum/accounts/abi"
    "golang.org/x/tools/imports"
)

// Lang is a target programming language selector to generate bindings for.
type Lang int

const (
    LangGo Lang = iota
    LangJava
    LangObjC
)

// 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(types []string, abis []string, bytecodes []string, pkg string, lang Lang) (string, error) {
    // Process each individual contract requested binding
    contracts := make(map[string]*tmplContract)

    for i := 0; i < len(types); i++ {
        // Parse the actual ABI to generate the binding for
        evmABI, err := abi.JSON(strings.NewReader(abis[i]))
        if err != nil {
            return "", err
        }
        // Strip any whitespace from the JSON ABI
        strippedABI := strings.Map(func(r rune) rune {
            if unicode.IsSpace(r) {
                return -1
            }
            return r
        }, abis[i])

        // Extract the call and transact methods; events; and sort them alphabetically
        var (
            calls     = make(map[string]*tmplMethod)
            transacts = make(map[string]*tmplMethod)
            events    = make(map[string]*tmplEvent)
        )
        for _, original := range evmABI.Methods {
            // Normalize the method for capital cases and non-anonymous inputs/outputs
            normalized := original
            normalized.Name = methodNormalizer[lang](original.Name)

            normalized.Inputs = make([]abi.Argument, len(original.Inputs))
            copy(normalized.Inputs, original.Inputs)
            for j, input := range normalized.Inputs {
                if input.Name == "" {
                    normalized.Inputs[j].Name = fmt.Sprintf("arg%d", j)
                }
            }
            normalized.Outputs = make([]abi.Argument, len(original.Outputs))
            copy(normalized.Outputs, original.Outputs)
            for j, output := range normalized.Outputs {
                if output.Name != "" {
                    normalized.Outputs[j].Name = capitalise(output.Name)
                }
            }
            // Append the methods to the call or transact lists
            if original.Const {
                calls[original.Name] = &tmplMethod{Original: original, Normalized: normalized, Structured: structured(original.Outputs)}
            } else {
                transacts[original.Name] = &tmplMethod{Original: original, Normalized: normalized, Structured: structured(original.Outputs)}
            }
        }
        for _, original := range evmABI.Events {
            // Skip anonymous events as they don't support explicit filtering
            if original.Anonymous {
                continue
            }
            // Normalize the event for capital cases and non-anonymous outputs
            normalized := original
            normalized.Name = methodNormalizer[lang](original.Name)

            normalized.Inputs = make([]abi.Argument, len(original.Inputs))
            copy(normalized.Inputs, original.Inputs)
            for j, input := range normalized.Inputs {
                // Indexed fields are input, non-indexed ones are outputs
                if input.Indexed {
                    if input.Name == "" {
                        normalized.Inputs[j].Name = fmt.Sprintf("arg%d", j)
                    }
                }
            }
            // Append the event to the accumulator list
            events[original.Name] = &tmplEvent{Original: original, Normalized: normalized}
        }
        contracts[types[i]] = &tmplContract{
            Type:        capitalise(types[i]),
            InputABI:    strings.Replace(strippedABI, "\"", "\\\"", -1),
            InputBin:    strings.TrimSpace(bytecodes[i]),
            Constructor: evmABI.Constructor,
            Calls:       calls,
            Transacts:   transacts,
            Events:      events,
        }
    }
    // Generate the contract template data content and render it
    data := &tmplData{
        Package:   pkg,
        Contracts: contracts,
    }
    buffer := new(bytes.Buffer)

    funcs := map[string]interface{}{
        "bindtype":      bindType[lang],
        "bindtopictype": bindTopicType[lang],
        "namedtype":     namedType[lang],
        "capitalise":    capitalise,
        "decapitalise":  decapitalise,
    }
    tmpl := template.Must(template.New("").Funcs(funcs).Parse(tmplSource[lang]))
    if err := tmpl.Execute(buffer, data); err != nil {
        return "", err
    }
    // For Go bindings pass the code through goimports to clean it up and double check
    if lang == LangGo {
        code, err := imports.Process(".", buffer.Bytes(), nil)
        if err != nil {
            return "", fmt.Errorf("%v\n%s", err, buffer)
        }
        return string(code), nil
    }
    // For all others just return as is for now
    return buffer.String(), nil
}

// bindType is a set of type binders that convert Solidity types to some supported
// programming language types.
var bindType = map[Lang]func(kind abi.Type) string{
    LangGo:   bindTypeGo,
    LangJava: bindTypeJava,
}

// Helper function for the binding generators.
// It reads the unmatched characters after the inner type-match,
//  (since the inner type is a prefix of the total type declaration),
//  looks for valid arrays (possibly a dynamic one) wrapping the inner type,
//  and returns the sizes of these arrays.
//
// Returned array sizes are in the same order as solidity signatures; inner array size first.
// Array sizes may also be "", indicating a dynamic array.
func wrapArray(stringKind string, innerLen int, innerMapping string) (string, []string) {
    remainder := stringKind[innerLen:]
    //find all the sizes
    matches := regexp.MustCompile(`\[(\d*)\]`).FindAllStringSubmatch(remainder, -1)
    parts := make([]string, 0, len(matches))
    for _, match := range matches {
        //get group 1 from the regex match
        parts = append(parts, match[1])
    }
    return innerMapping, parts
}

// Translates the array sizes to a Go-lang declaration of a (nested) array of the inner type.
// Simply returns the inner type if arraySizes is empty.
func arrayBindingGo(inner string, arraySizes []string) string {
    out := ""
    //prepend all array sizes, from outer (end arraySizes) to inner (start arraySizes)
    for i := len(arraySizes) - 1; i >= 0; i-- {
        out += "[" + arraySizes[i] + "]"
    }
    out += inner
    return out
}

// bindTypeGo 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 bindTypeGo(kind abi.Type) string {
    stringKind := kind.String()
    innerLen, innerMapping := bindUnnestedTypeGo(stringKind)
    return arrayBindingGo(wrapArray(stringKind, innerLen, innerMapping))
}

// The inner function of bindTypeGo, this finds the inner type of stringKind.
// (Or just the type itself if it is not an array or slice)
// The length of the matched part is returned, with the the translated type.
func bindUnnestedTypeGo(stringKind string) (int, string) {

    switch {
    case strings.HasPrefix(stringKind, "address"):
        return len("address"), "common.Address"

    case strings.HasPrefix(stringKind, "bytes"):
        parts := regexp.MustCompile(`bytes([0-9]*)`).FindStringSubmatch(stringKind)
        return len(parts[0]), fmt.Sprintf("[%s]byte", parts[1])

    case strings.HasPrefix(stringKind, "int") || strings.HasPrefix(stringKind, "uint"):
        parts := regexp.MustCompile(`(u)?int([0-9]*)`).FindStringSubmatch(stringKind)
        switch parts[2] {
        case "8", "16", "32", "64":
            return len(parts[0]), fmt.Sprintf("%sint%s", parts[1], parts[2])
        }
        return len(parts[0]), "*big.Int"

    case strings.HasPrefix(stringKind, "bool"):
        return len("bool"), "bool"

    case strings.HasPrefix(stringKind, "string"):
        return len("string"), "string"

    default:
        return len(stringKind), stringKind
    }
}

// Translates the array sizes to a Java declaration of a (nested) array of the inner type.
// Simply returns the inner type if arraySizes is empty.
func arrayBindingJava(inner string, arraySizes []string) string {
    // Java array type declarations do not include the length.
    return inner + strings.Repeat("[]", len(arraySizes))
}

// bindTypeJava converts a Solidity type to a Java one. Since there is no clear mapping
// from all Solidity types to Java ones (e.g. uint17), those that cannot be exactly
// mapped will use an upscaled type (e.g. BigDecimal).
func bindTypeJava(kind abi.Type) string {
    stringKind := kind.String()
    innerLen, innerMapping := bindUnnestedTypeJava(stringKind)
    return arrayBindingJava(wrapArray(stringKind, innerLen, innerMapping))
}

// The inner function of bindTypeJava, this finds the inner type of stringKind.
// (Or just the type itself if it is not an array or slice)
// The length of the matched part is returned, with the the translated type.
func bindUnnestedTypeJava(stringKind string) (int, string) {

    switch {
    case strings.HasPrefix(stringKind, "address"):
        parts := regexp.MustCompile(`address(\[[0-9]*\])?`).FindStringSubmatch(stringKind)
        if len(parts) != 2 {
            return len(stringKind), stringKind
        }
        if parts[1] == "" {
            return len("address"), "Address"
        }
        return len(parts[0]), "Addresses"

    case strings.HasPrefix(stringKind, "bytes"):
        parts := regexp.MustCompile(`bytes([0-9]*)`).FindStringSubmatch(stringKind)
        if len(parts) != 2 {
            return len(stringKind), stringKind
        }
        return len(parts[0]), "byte[]"

    case strings.HasPrefix(stringKind, "int") || strings.HasPrefix(stringKind, "uint"):
        //Note that uint and int (without digits) are also matched,
        // these are size 256, and will translate to BigInt (the default).
        parts := regexp.MustCompile(`(u)?int([0-9]*)`).FindStringSubmatch(stringKind)
        if len(parts) != 3 {
            return len(stringKind), stringKind
        }

        namedSize := map[string]string{
            "8":  "byte",
            "16": "short",
            "32": "int",
            "64": "long",
        }[parts[2]]

        //default to BigInt
        if namedSize == "" {
            namedSize = "BigInt"
        }
        return len(parts[0]), namedSize

    case strings.HasPrefix(stringKind, "bool"):
        return len("bool"), "boolean"

    case strings.HasPrefix(stringKind, "string"):
        return len("string"), "String"

    default:
        return len(stringKind), stringKind
    }
}

// bindTopicType is a set of type binders that convert Solidity types to some
// supported programming language topic types.
var bindTopicType = map[Lang]func(kind abi.Type) string{
    LangGo:   bindTopicTypeGo,
    LangJava: bindTopicTypeJava,
}

// bindTypeGo converts a Solidity topic type to a Go one. It is almost the same
// funcionality as for simple types, but dynamic types get converted to hashes.
func bindTopicTypeGo(kind abi.Type) string {
    bound := bindTypeGo(kind)
    if bound == "string" || bound == "[]byte" {
        bound = "common.Hash"
    }
    return bound
}

// bindTypeGo converts a Solidity topic type to a Java one. It is almost the same
// funcionality as for simple types, but dynamic types get converted to hashes.
func bindTopicTypeJava(kind abi.Type) string {
    bound := bindTypeJava(kind)
    if bound == "String" || bound == "Bytes" {
        bound = "Hash"
    }
    return bound
}

// namedType is a set of functions that transform language specific types to
// named versions that my be used inside method names.
var namedType = map[Lang]func(string, abi.Type) string{
    LangGo:   func(string, abi.Type) string { panic("this shouldn't be needed") },
    LangJava: namedTypeJava,
}

// namedTypeJava converts some primitive data types to named variants that can
// be used as parts of method names.
func namedTypeJava(javaKind string, solKind abi.Type) string {
    switch javaKind {
    case "byte[]":
        return "Binary"
    case "byte[][]":
        return "Binaries"
    case "string":
        return "String"
    case "string[]":
        return "Strings"
    case "boolean":
        return "Bool"
    case "boolean[]":
        return "Bools"
    case "BigInt[]":
        return "BigInts"
    default:
        parts := regexp.MustCompile(`(u)?int([0-9]*)(\[[0-9]*\])?`).FindStringSubmatch(solKind.String())
        if len(parts) != 4 {
            return javaKind
        }
        switch parts[2] {
        case "8", "16", "32", "64":
            if parts[3] == "" {
                return capitalise(fmt.Sprintf("%sint%s", parts[1], parts[2]))
            }
            return capitalise(fmt.Sprintf("%sint%ss", parts[1], parts[2]))

        default:
            return javaKind
        }
    }
}

// methodNormalizer is a name transformer that modifies Solidity method names to
// conform to target language naming concentions.
var methodNormalizer = map[Lang]func(string) string{
    LangGo:   capitalise,
    LangJava: decapitalise,
}

// capitalise makes a camel-case string which starts with an upper case character.
func capitalise(input string) string {
    for len(input) > 0 && input[0] == '_' {
        input = input[1:]
    }
    if len(input) == 0 {
        return ""
    }
    return toCamelCase(strings.ToUpper(input[:1]) + input[1:])
}

// decapitalise makes a camel-case string which starts with a lower case character.
func decapitalise(input string) string {
    for len(input) > 0 && input[0] == '_' {
        input = input[1:]
    }
    if len(input) == 0 {
        return ""
    }
    return toCamelCase(strings.ToLower(input[:1]) + input[1:])
}

// toCamelCase converts an under-score string to a camel-case string
func toCamelCase(input string) string {
    toupper := false

    result := ""
    for k, v := range input {
        switch {
        case k == 0:
            result = strings.ToUpper(string(input[0]))

        case toupper:
            result += strings.ToUpper(string(v))
            toupper = false

        case v == '_':
            toupper = true

        default:
            result += string(v)
        }
    }
    return result
}

// structured checks whether a list of ABI data types has enough information to
// operate through a proper Go struct or if flat returns are needed.
func structured(args abi.Arguments) bool {
    if len(args) < 2 {
        return false
    }
    exists := make(map[string]bool)
    for _, out := range args {
        // If the name is anonymous, we can't organize into a struct
        if out.Name == "" {
            return false
        }
        // If the field name is empty when normalized or collides (var, Var, _var, _Var),
        // we can't organize into a struct
        field := capitalise(out.Name)
        if field == "" || exists[field] {
            return false
        }
        exists[field] = true
    }
    return true
}