packer-cn/hcl2template/shim/values.go

133 lines
3.9 KiB
Go

package hcl2shim
import (
"fmt"
"math/big"
"github.com/zclconf/go-cty/cty"
)
// UnknownVariableValue is a sentinel value that can be used
// to denote that the value of a variable is unknown at this time.
// RawConfig uses this information to build up data about
// unknown keys.
const UnknownVariableValue = "74D93920-ED26-11E3-AC10-0800200C9A66"
// ConfigValueFromHCL2 converts a value from HCL2 (really, from the cty dynamic
// types library that HCL2 uses) to a value type that matches what would've
// been produced from the HCL-based interpolator for an equivalent structure.
//
// This function will transform a cty null value into a Go nil value, which
// isn't a possible outcome of the HCL/HIL-based decoder and so callers may
// need to detect and reject any null values.
func ConfigValueFromHCL2(v cty.Value) interface{} {
if !v.IsKnown() {
return UnknownVariableValue
}
if v.IsNull() {
return nil
}
switch v.Type() {
case cty.Bool:
return v.True() // like HCL.BOOL
case cty.String:
return v.AsString() // like HCL token.STRING or token.HEREDOC
case cty.Number:
// We can't match HCL _exactly_ here because it distinguishes between
// int and float values, but we'll get as close as we can by using
// an int if the number is exactly representable, and a float if not.
// The conversion to float will force precision to that of a float64,
// which is potentially losing information from the specific number
// given, but no worse than what HCL would've done in its own conversion
// to float.
f := v.AsBigFloat()
if i, acc := f.Int64(); acc == big.Exact {
// if we're on a 32-bit system and the number is too big for 32-bit
// int then we'll fall through here and use a float64.
const MaxInt = int(^uint(0) >> 1)
const MinInt = -MaxInt - 1
if i <= int64(MaxInt) && i >= int64(MinInt) {
return int(i) // Like HCL token.NUMBER
}
}
f64, _ := f.Float64()
return f64 // like HCL token.FLOAT
}
if v.Type().IsListType() || v.Type().IsSetType() || v.Type().IsTupleType() {
l := make([]interface{}, 0, v.LengthInt())
it := v.ElementIterator()
for it.Next() {
_, ev := it.Element()
l = append(l, ConfigValueFromHCL2(ev))
}
return l
}
if v.Type().IsMapType() || v.Type().IsObjectType() {
l := make(map[string]interface{})
it := v.ElementIterator()
for it.Next() {
ek, ev := it.Element()
cv := ConfigValueFromHCL2(ev)
if cv != nil {
l[ek.AsString()] = cv
}
}
return l
}
// If we fall out here then we have some weird type that we haven't
// accounted for. This should never happen unless the caller is using
// capsule types, and we don't currently have any such types defined.
panic(fmt.Errorf("can't convert %#v to config value", v))
}
// HCL2ValueFromConfigValue is the opposite of ConfigValueFromHCL2: it takes
// a value as would be returned from the old interpolator and turns it into
// a cty.Value so it can be used within, for example, an HCL2 EvalContext.
func HCL2ValueFromConfigValue(v interface{}) cty.Value {
if v == nil {
return cty.NullVal(cty.DynamicPseudoType)
}
if v == UnknownVariableValue {
return cty.DynamicVal
}
switch tv := v.(type) {
case bool:
return cty.BoolVal(tv)
case string:
return cty.StringVal(tv)
case int:
return cty.NumberIntVal(int64(tv))
case float64:
return cty.NumberFloatVal(tv)
case []interface{}:
vals := make([]cty.Value, len(tv))
for i, ev := range tv {
vals[i] = HCL2ValueFromConfigValue(ev)
}
return cty.TupleVal(vals)
case []string:
vals := make([]cty.Value, len(tv))
for i, ev := range tv {
vals[i] = cty.StringVal(ev)
}
return cty.ListVal(vals)
case map[string]interface{}:
vals := map[string]cty.Value{}
for k, ev := range tv {
vals[k] = HCL2ValueFromConfigValue(ev)
}
return cty.ObjectVal(vals)
default:
// HCL/HIL should never generate anything that isn't caught by
// the above, so if we get here something has gone very wrong.
panic(fmt.Errorf("can't convert %#v to cty.Value", v))
}
}