packer-cn/hcl2template/function/index.go

59 lines
1.4 KiB
Go

package function
import (
"errors"
"github.com/zclconf/go-cty/cty"
"github.com/zclconf/go-cty/cty/function"
"github.com/zclconf/go-cty/cty/function/stdlib"
)
// IndexFunc constructs a function that finds the element index for a given value in a list.
var IndexFunc = function.New(&function.Spec{
Params: []function.Parameter{
{
Name: "list",
Type: cty.DynamicPseudoType,
},
{
Name: "value",
Type: cty.DynamicPseudoType,
},
},
Type: function.StaticReturnType(cty.Number),
Impl: func(args []cty.Value, retType cty.Type) (ret cty.Value, err error) {
if !(args[0].Type().IsListType() || args[0].Type().IsTupleType()) {
return cty.NilVal, errors.New("argument must be a list or tuple")
}
if !args[0].IsKnown() {
return cty.UnknownVal(cty.Number), nil
}
if args[0].LengthInt() == 0 { // Easy path
return cty.NilVal, errors.New("cannot search an empty list")
}
for it := args[0].ElementIterator(); it.Next(); {
i, v := it.Element()
eq, err := stdlib.Equal(v, args[1])
if err != nil {
return cty.NilVal, err
}
if !eq.IsKnown() {
return cty.UnknownVal(cty.Number), nil
}
if eq.True() {
return i, nil
}
}
return cty.NilVal, errors.New("item not found")
},
})
// Index finds the element index for a given value in a list.
func Index(list, value cty.Value) (cty.Value, error) {
return IndexFunc.Call([]cty.Value{list, value})
}