terraform-provider-gitea/vendor/github.com/zclconf/go-cty/cty/gob.go

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2022-04-03 04:07:16 +00:00
package cty
import (
"bytes"
"encoding/gob"
"errors"
"fmt"
"math/big"
"github.com/zclconf/go-cty/cty/set"
)
// GobEncode is an implementation of the gob.GobEncoder interface, which
// allows Values to be included in structures encoded with encoding/gob.
//
// Currently it is not possible to represent values of capsule types in gob,
// because the types themselves cannot be represented.
func (val Value) GobEncode() ([]byte, error) {
if val.IsMarked() {
return nil, errors.New("value is marked")
}
buf := &bytes.Buffer{}
enc := gob.NewEncoder(buf)
gv := gobValue{
Version: 0,
Ty: val.ty,
V: val.v,
}
err := enc.Encode(gv)
if err != nil {
return nil, fmt.Errorf("error encoding cty.Value: %s", err)
}
return buf.Bytes(), nil
}
// GobDecode is an implementation of the gob.GobDecoder interface, which
// inverts the operation performed by GobEncode. See the documentation of
// GobEncode for considerations when using cty.Value instances with gob.
func (val *Value) GobDecode(buf []byte) error {
r := bytes.NewReader(buf)
dec := gob.NewDecoder(r)
var gv gobValue
err := dec.Decode(&gv)
if err != nil {
return fmt.Errorf("error decoding cty.Value: %s", err)
}
if gv.Version != 0 {
return fmt.Errorf("unsupported cty.Value encoding version %d; only 0 is supported", gv.Version)
}
// Because big.Float.GobEncode is implemented with a pointer reciever,
// gob encoding of an interface{} containing a *big.Float value does not
// round-trip correctly, emerging instead as a non-pointer big.Float.
// The rest of cty expects all number values to be represented by
// *big.Float, so we'll fix that up here.
gv.V = gobDecodeFixNumberPtr(gv.V, gv.Ty)
val.ty = gv.Ty
val.v = gv.V
return nil
}
// GobEncode is an implementation of the gob.GobEncoder interface, which
// allows Types to be included in structures encoded with encoding/gob.
//
// Currently it is not possible to represent capsule types in gob.
func (t Type) GobEncode() ([]byte, error) {
buf := &bytes.Buffer{}
enc := gob.NewEncoder(buf)
gt := gobType{
Version: 0,
Impl: t.typeImpl,
}
err := enc.Encode(gt)
if err != nil {
return nil, fmt.Errorf("error encoding cty.Type: %s", err)
}
return buf.Bytes(), nil
}
// GobDecode is an implementatino of the gob.GobDecoder interface, which
// reverses the encoding performed by GobEncode to allow types to be recovered
// from gob buffers.
func (t *Type) GobDecode(buf []byte) error {
r := bytes.NewReader(buf)
dec := gob.NewDecoder(r)
var gt gobType
err := dec.Decode(&gt)
if err != nil {
return fmt.Errorf("error decoding cty.Type: %s", err)
}
if gt.Version != 0 {
return fmt.Errorf("unsupported cty.Type encoding version %d; only 0 is supported", gt.Version)
}
t.typeImpl = gt.Impl
return nil
}
// Capsule types cannot currently be gob-encoded, because they rely on pointer
// equality and we have no way to recover the original pointer on decode.
func (t *capsuleType) GobEncode() ([]byte, error) {
return nil, fmt.Errorf("cannot gob-encode capsule type %q", t.FriendlyName(friendlyTypeName))
}
func (t *capsuleType) GobDecode() ([]byte, error) {
return nil, fmt.Errorf("cannot gob-decode capsule type %q", t.FriendlyName(friendlyTypeName))
}
type gobValue struct {
Version int
Ty Type
V interface{}
}
type gobType struct {
Version int
Impl typeImpl
}
type gobCapsuleTypeImpl struct {
}
// goDecodeFixNumberPtr fixes an unfortunate quirk of round-tripping cty.Number
// values through gob: the big.Float.GobEncode method is implemented on a
// pointer receiver, and so it loses the "pointer-ness" of the value on
// encode, causing the values to emerge the other end as big.Float rather than
// *big.Float as we expect elsewhere in cty.
//
// The implementation of gobDecodeFixNumberPtr mutates the given raw value
// during its work, and may either return the same value mutated or a new
// value. Callers must no longer use whatever value they pass as "raw" after
// this function is called.
func gobDecodeFixNumberPtr(raw interface{}, ty Type) interface{} {
// Unfortunately we need to work recursively here because number values
// might be embedded in structural or collection type values.
switch {
case ty.Equals(Number):
if bf, ok := raw.(big.Float); ok {
return &bf // wrap in pointer
}
case ty.IsMapType() && ty.ElementType().Equals(Number):
if m, ok := raw.(map[string]interface{}); ok {
for k, v := range m {
m[k] = gobDecodeFixNumberPtr(v, ty.ElementType())
}
}
case ty.IsListType() && ty.ElementType().Equals(Number):
if s, ok := raw.([]interface{}); ok {
for i, v := range s {
s[i] = gobDecodeFixNumberPtr(v, ty.ElementType())
}
}
case ty.IsSetType() && ty.ElementType().Equals(Number):
if s, ok := raw.(set.Set); ok {
newS := set.NewSet(s.Rules())
for it := s.Iterator(); it.Next(); {
newV := gobDecodeFixNumberPtr(it.Value(), ty.ElementType())
newS.Add(newV)
}
return newS
}
case ty.IsObjectType():
if m, ok := raw.(map[string]interface{}); ok {
for k, v := range m {
aty := ty.AttributeType(k)
m[k] = gobDecodeFixNumberPtr(v, aty)
}
}
case ty.IsTupleType():
if s, ok := raw.([]interface{}); ok {
for i, v := range s {
ety := ty.TupleElementType(i)
s[i] = gobDecodeFixNumberPtr(v, ety)
}
}
}
return raw
}
// gobDecodeFixNumberPtrVal is a helper wrapper around gobDecodeFixNumberPtr
// that works with already-constructed values. This is primarily for testing,
// to fix up intentionally-invalid number values for the parts of the test
// code that need them to be valid, such as calling GoString on them.
func gobDecodeFixNumberPtrVal(v Value) Value {
raw := gobDecodeFixNumberPtr(v.v, v.ty)
return Value{
v: raw,
ty: v.ty,
}
}