// Copyright 2016-2023, Pulumi Corporation. // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. package internal import ( "fmt" "reflect" "github.com/pulumi/pulumi/sdk/v3/go/common/util/contract" ) // MapStructTypes returns a function that maps the fields of struct type 'from' // to the fields of struct type 'to'. // // The returned function takes a value of type 'to' // and an index of a field in 'from', // and returns the corresponding field in 'to'. // The value may be omitted if just the field's type information is needed. func MapStructTypes(from, to reflect.Type) func(reflect.Value, int) (reflect.StructField, reflect.Value) { contract.Assertf(from.Kind() == reflect.Struct, "from must be a struct type, got %v (%v)", from, from.Kind()) contract.Assertf(to.Kind() == reflect.Struct, "to must be a struct type, got %v (%v)", to, to.Kind()) if from == to { return func(v reflect.Value, i int) (reflect.StructField, reflect.Value) { var fv reflect.Value if v.IsValid() { fv = v.Field(i) } return to.Field(i), fv } } nameToIndex := map[string]int{} numFields := to.NumField() for i := 0; i < numFields; i++ { nameToIndex[to.Field(i).Name] = i } return func(v reflect.Value, i int) (reflect.StructField, reflect.Value) { fieldName := from.Field(i).Name j, ok := nameToIndex[fieldName] if !ok { panic(fmt.Errorf("unknown field %v when marshaling inputs of type %v to %v", fieldName, from, to)) } field := to.Field(j) var fieldValue reflect.Value if v.IsValid() { fieldValue = v.Field(j) } return field, fieldValue } }