forked from stellar/go
/
asset.go
197 lines (175 loc) · 5.11 KB
/
asset.go
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package xdr
import (
"errors"
"fmt"
"strings"
"github.com/stellar/go/strkey"
)
// This file contains helpers for working with xdr.Asset structs
// MustNewNativeAsset returns a new native asset, panicking if it can't.
func MustNewNativeAsset() Asset {
a := Asset{}
err := a.SetNative()
if err != nil {
panic(err)
}
return a
}
// MustNewCreditAsset returns a new general asset, panicking if it can't.
func MustNewCreditAsset(code string, issuer string) Asset {
a := Asset{}
accountID := AccountId{}
accountID.SetAddress(issuer)
err := a.SetCredit(code, accountID)
if err != nil {
panic(err)
}
return a
}
// SetCredit overwrites `a` with a credit asset using `code` and `issuer`. The
// asset type (CreditAlphanum4 or CreditAlphanum12) is chosen automatically
// based upon the length of `code`.
func (a *Asset) SetCredit(code string, issuer AccountId) error {
length := len(code)
var typ AssetType
var body interface{}
switch {
case length >= 1 && length <= 4:
newbody := AssetAlphaNum4{Issuer: issuer}
copy(newbody.AssetCode[:], []byte(code)[:length])
typ = AssetTypeAssetTypeCreditAlphanum4
body = newbody
case length >= 5 && length <= 12:
newbody := AssetAlphaNum12{Issuer: issuer}
copy(newbody.AssetCode[:], []byte(code)[:length])
typ = AssetTypeAssetTypeCreditAlphanum12
body = newbody
default:
return errors.New("Asset code length is invalid")
}
newa, err := NewAsset(typ, body)
if err != nil {
return err
}
*a = newa
return nil
}
// SetNative overwrites `a` with the native asset type
func (a *Asset) SetNative() error {
newa, err := NewAsset(AssetTypeAssetTypeNative, nil)
if err != nil {
return err
}
*a = newa
return nil
}
// ToAllowTrustOpAsset for Asset converts the Asset to a corresponding XDR
// "allow trust" asset, used by the XDR allow trust operation.
func (a *Asset) ToAllowTrustOpAsset(code string) (AllowTrustOpAsset, error) {
length := len(code)
switch {
case length >= 1 && length <= 4:
var bytecode [4]byte
byteArray := []byte(code)
copy(bytecode[:], byteArray[0:length])
return NewAllowTrustOpAsset(AssetTypeAssetTypeCreditAlphanum4, bytecode)
case length >= 5 && length <= 12:
var bytecode [12]byte
byteArray := []byte(code)
copy(bytecode[:], byteArray[0:length])
return NewAllowTrustOpAsset(AssetTypeAssetTypeCreditAlphanum12, bytecode)
default:
return AllowTrustOpAsset{}, errors.New("Asset code length is invalid")
}
}
// String returns a display friendly form of the asset
func (a Asset) String() string {
var t, c, i string
a.MustExtract(&t, &c, &i)
if a.Type == AssetTypeAssetTypeNative {
return t
}
return fmt.Sprintf("%s/%s/%s", t, c, i)
}
// Equals returns true if `other` is equivalent to `a`
func (a Asset) Equals(other Asset) bool {
if a.Type != other.Type {
return false
}
switch a.Type {
case AssetTypeAssetTypeNative:
return true
case AssetTypeAssetTypeCreditAlphanum4:
l := a.MustAlphaNum4()
r := other.MustAlphaNum4()
return l.AssetCode == r.AssetCode && l.Issuer.Equals(r.Issuer)
case AssetTypeAssetTypeCreditAlphanum12:
l := a.MustAlphaNum12()
r := other.MustAlphaNum12()
return l.AssetCode == r.AssetCode && l.Issuer.Equals(r.Issuer)
default:
panic(fmt.Errorf("Unknown asset type: %v", a.Type))
}
}
// Extract is a helper function to extract information from an xdr.Asset
// structure. It extracts the asset's type to the `typ` input parameter (which
// must be either a *string or *xdr.AssetType). It also extracts the asset's
// code and issuer to `code` and `issuer` respectively if they are of type
// *string and the asset is non-native
func (a Asset) Extract(typ interface{}, code interface{}, issuer interface{}) error {
switch typ := typ.(type) {
case *AssetType:
*typ = a.Type
case *string:
switch a.Type {
case AssetTypeAssetTypeNative:
*typ = "native"
case AssetTypeAssetTypeCreditAlphanum4:
*typ = "credit_alphanum4"
case AssetTypeAssetTypeCreditAlphanum12:
*typ = "credit_alphanum12"
}
default:
return errors.New("can't extract type")
}
if code != nil {
switch code := code.(type) {
case *string:
switch a.Type {
case AssetTypeAssetTypeCreditAlphanum4:
an := a.MustAlphaNum4()
*code = strings.TrimRight(string(an.AssetCode[:]), "\x00")
case AssetTypeAssetTypeCreditAlphanum12:
an := a.MustAlphaNum12()
*code = strings.TrimRight(string(an.AssetCode[:]), "\x00")
}
default:
return errors.New("can't extract code")
}
}
if issuer != nil {
switch issuer := issuer.(type) {
case *string:
switch a.Type {
case AssetTypeAssetTypeCreditAlphanum4:
an := a.MustAlphaNum4()
raw := an.Issuer.MustEd25519()
*issuer = strkey.MustEncode(strkey.VersionByteAccountID, raw[:])
case AssetTypeAssetTypeCreditAlphanum12:
an := a.MustAlphaNum12()
raw := an.Issuer.MustEd25519()
*issuer = strkey.MustEncode(strkey.VersionByteAccountID, raw[:])
}
default:
return errors.New("can't extract issuer")
}
}
return nil
}
// MustExtract behaves as Extract, but panics if an error occurs.
func (a Asset) MustExtract(typ interface{}, code interface{}, issuer interface{}) {
err := a.Extract(typ, code, issuer)
if err != nil {
panic(err)
}
}