pulumi/sdk/go/common/util/mapper/mapper_decode.go

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2018-05-22 19:43:36 +00:00
// Copyright 2016-2018, 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 mapper
import (
"encoding"
"fmt"
"reflect"
"github.com/pulumi/pulumi/sdk/v3/go/common/util/contract"
)
// Decoder is a func that knows how to decode into particular type.
type Decoder func(m Mapper, obj map[string]interface{}) (interface{}, error)
// Decoders is a map from type to a decoder func that understands how to decode that type.
type Decoders map[reflect.Type]Decoder
// Decode decodes an entire map into a target object, using tag-directed mappings.
func (md *mapper) Decode(obj map[string]interface{}, target interface{}) MappingError {
// Fetch the destination types and validate that we can store into the target (i.e., a valid lval).
vdst := reflect.ValueOf(target)
contract.Assertf(vdst.Kind() == reflect.Ptr && !vdst.IsNil() && vdst.Elem().CanSet(),
"Target %v must be a non-nil, settable pointer", vdst.Type())
vdstType := vdst.Type().Elem()
contract.Assertf(vdstType.Kind() == reflect.Struct && !vdst.IsNil(),
"Target %v must be a struct type with `pulumi:\"x\"` tags to direct decoding", vdstType)
// Keep track of any errors that result.
var errs []error
// For each field in the struct that has a `pulumi:"name"`, look it up in the map by that `name`, issuing an error
// if it is missing or of the wrong type. For each field that is marked optional, e.g. `pulumi:"name,optional"`,
// do the same, but permit it to be missing without issuing an error.
flds := make(map[string]bool)
for _, fldtag := range md.structFieldsTags(vdstType) {
// Use the tag to direct unmarshaling.
key := fldtag.Key
if !fldtag.Skip {
fld := vdst.Elem().FieldByName(fldtag.Info.Name)
if err := md.DecodeValue(obj, vdstType, key, fld.Addr().Interface(), fldtag.Optional); err != nil {
errs = append(errs, err)
}
}
// Remember this key so we can be sure not to reject it later when checking for unrecognized fields.
flds[key] = true
}
// Afterwards, if there are any unrecognized fields, issue an error.
if !md.opts.IgnoreUnrecognized {
for k := range obj {
if !flds[k] {
err := NewUnrecognizedError(vdstType, k)
errs = append(errs, err)
}
}
}
// If there are no errors, return nil; else manufacture a decode error object.
if len(errs) == 0 {
return nil
}
return NewMappingError(errs)
}
// DecodeValue decodes primitive type fields. For fields of complex types, we use custom deserialization.
func (md *mapper) DecodeValue(obj map[string]interface{}, ty reflect.Type, key string,
all: Reformat with gofumpt Per team discussion, switching to gofumpt. [gofumpt][1] is an alternative, stricter alternative to gofmt. It addresses other stylistic concerns that gofmt doesn't yet cover. [1]: https://github.com/mvdan/gofumpt See the full list of [Added rules][2], but it includes: - Dropping empty lines around function bodies - Dropping unnecessary variable grouping when there's only one variable - Ensuring an empty line between multi-line functions - simplification (`-s` in gofmt) is always enabled - Ensuring multi-line function signatures end with `) {` on a separate line. [2]: https://github.com/mvdan/gofumpt#Added-rules gofumpt is stricter, but there's no lock-in. All gofumpt output is valid gofmt output, so if we decide we don't like it, it's easy to switch back without any code changes. gofumpt support is built into the tooling we use for development so this won't change development workflows. - golangci-lint includes a gofumpt check (enabled in this PR) - gopls, the LSP for Go, includes a gofumpt option (see [installation instrutions][3]) [3]: https://github.com/mvdan/gofumpt#installation This change was generated by running: ```bash gofumpt -w $(rg --files -g '*.go' | rg -v testdata | rg -v compilation_error) ``` The following files were manually tweaked afterwards: - pkg/cmd/pulumi/stack_change_secrets_provider.go: one of the lines overflowed and had comments in an inconvenient place - pkg/cmd/pulumi/destroy.go: `var x T = y` where `T` wasn't necessary - pkg/cmd/pulumi/policy_new.go: long line because of error message - pkg/backend/snapshot_test.go: long line trying to assign three variables in the same assignment I have included mention of gofumpt in the CONTRIBUTING.md.
2023-03-03 16:36:39 +00:00
target interface{}, optional bool,
) FieldError {
vdst := reflect.ValueOf(target)
contract.Assertf(vdst.Kind() == reflect.Ptr && !vdst.IsNil() && vdst.Elem().CanSet(),
"Target %v must be a non-nil, settable pointer", vdst.Type())
if v, has := obj[key]; has {
// The field exists; okay, try to map it to the right type.
vsrc := reflect.ValueOf(v)
// If the source is a ptr, dereference it as necessary to get the underlying
// value.
for vsrc.IsValid() && vsrc.Type().Kind() == reflect.Ptr && !vsrc.IsNil() {
vsrc = vsrc.Elem()
}
// Ensure the source is valid; this is false if the value reflects the zero value.
if vsrc.IsValid() {
vdstType := vdst.Type().Elem()
// So long as the target element is a pointer, we have a pointer to pointer; dig through until we bottom out
// on the non-pointer type that matches the source. This assumes the source isn't itself a pointer!
contract.Assertf(vsrc.Type().Kind() != reflect.Ptr, "source is a null pointer")
for vdstType.Kind() == reflect.Ptr {
vdst = vdst.Elem()
vdstType = vdstType.Elem()
if !vdst.Elem().CanSet() {
// If the pointer is nil, initialize it so we can set it below.
contract.Assertf(vdst.IsNil(), "destination pointer must be nil")
vdst.Set(reflect.New(vdstType))
}
}
// Adjust the value if necessary; this handles recursive struct marshaling, interface unboxing, and more.
var err FieldError
if vsrc, err = md.adjustValueForAssignment(vsrc, vdstType, ty, key); err != nil {
return err
}
// Finally, provided everything is kosher, go ahead and store the value; otherwise, issue an error.
if vsrc.Type().AssignableTo(vdstType) {
vdst.Elem().Set(vsrc)
return nil
}
return NewWrongTypeError(ty, key, vdstType, vsrc.Type())
}
}
if !optional && !md.opts.IgnoreMissing {
// The field doesn't exist and yet it is required; issue an error.
return NewMissingError(ty, key)
}
return nil
}
var (
emptyObject = map[string]interface{}{}
textUnmarshalerType = reflect.TypeOf(new(encoding.TextUnmarshaler)).Elem()
)
// adjustValueForAssignment converts if possible to produce the target type.
func (md *mapper) adjustValueForAssignment(val reflect.Value,
all: Reformat with gofumpt Per team discussion, switching to gofumpt. [gofumpt][1] is an alternative, stricter alternative to gofmt. It addresses other stylistic concerns that gofmt doesn't yet cover. [1]: https://github.com/mvdan/gofumpt See the full list of [Added rules][2], but it includes: - Dropping empty lines around function bodies - Dropping unnecessary variable grouping when there's only one variable - Ensuring an empty line between multi-line functions - simplification (`-s` in gofmt) is always enabled - Ensuring multi-line function signatures end with `) {` on a separate line. [2]: https://github.com/mvdan/gofumpt#Added-rules gofumpt is stricter, but there's no lock-in. All gofumpt output is valid gofmt output, so if we decide we don't like it, it's easy to switch back without any code changes. gofumpt support is built into the tooling we use for development so this won't change development workflows. - golangci-lint includes a gofumpt check (enabled in this PR) - gopls, the LSP for Go, includes a gofumpt option (see [installation instrutions][3]) [3]: https://github.com/mvdan/gofumpt#installation This change was generated by running: ```bash gofumpt -w $(rg --files -g '*.go' | rg -v testdata | rg -v compilation_error) ``` The following files were manually tweaked afterwards: - pkg/cmd/pulumi/stack_change_secrets_provider.go: one of the lines overflowed and had comments in an inconvenient place - pkg/cmd/pulumi/destroy.go: `var x T = y` where `T` wasn't necessary - pkg/cmd/pulumi/policy_new.go: long line because of error message - pkg/backend/snapshot_test.go: long line trying to assign three variables in the same assignment I have included mention of gofumpt in the CONTRIBUTING.md.
2023-03-03 16:36:39 +00:00
to reflect.Type, ty reflect.Type, key string,
) (reflect.Value, FieldError) {
for !val.Type().AssignableTo(to) {
// The source cannot be assigned directly to the destination. Go through all known conversions.
if val.Type().ConvertibleTo(to) {
// A simple conversion exists to make this right.
val = val.Convert(to)
} else if to.Kind() == reflect.Ptr && val.Type().AssignableTo(to.Elem()) {
// Here the destination type (to) is a pointer to a type that accepts val.
var adjusted reflect.Value // var adjusted *toElem
if val.CanAddr() && val.Addr().Type().AssignableTo(to) {
// If taking the address of val makes this right, do it.
adjusted = val.Addr() // adjusted = &val
} else {
// Otherwise create a fresh pointer of the desired type and point it to val.
adjusted = reflect.New(to.Elem()) // adjusted = new(toElem)
adjusted.Elem().Set(val) // *adjusted = val
}
// In either case, the loop condition should be sastisfied at this point.
contract.Assertf(adjusted.Type().AssignableTo(to), "type %v is not assignable to %v", adjusted.Type(), to)
return adjusted, nil
} else if val.Kind() == reflect.Interface {
// It could be that the source is an interface{} with the right element type (or the right element type
// through a series of successive conversions); go ahead and give it a try.
val = val.Elem()
} else if val.Type().Kind() == reflect.Slice && to.Kind() == reflect.Slice {
// If a slice, everything's ok so long as the elements are compatible.
arr := reflect.New(to).Elem()
for i := 0; i < val.Len(); i++ {
elem := val.Index(i)
if !elem.Type().AssignableTo(to.Elem()) {
ekey := fmt.Sprintf("%v[%v]", key, i)
var err FieldError
if elem, err = md.adjustValueForAssignment(elem, to.Elem(), ty, ekey); err != nil {
return val, err
}
if !elem.Type().AssignableTo(to.Elem()) {
return val, NewWrongTypeError(ty, ekey, to.Elem(), elem.Type())
}
}
arr = reflect.Append(arr, elem)
}
val = arr
} else if val.Type().Kind() == reflect.Map && to.Kind() == reflect.Map {
// Similarly, if a map, everything's ok so long as elements and keys are compatible.
m := reflect.MakeMap(to)
for _, k := range val.MapKeys() {
entry := val.MapIndex(k)
if !k.Type().AssignableTo(to.Key()) {
kkey := fmt.Sprintf("%v[%v] key", key, k.Interface())
var err FieldError
if k, err = md.adjustValueForAssignment(k, to.Key(), ty, kkey); err != nil {
return val, err
}
if !k.Type().AssignableTo(to.Key()) {
return val, NewWrongTypeError(ty, kkey, to.Key(), k.Type())
}
}
if !entry.Type().AssignableTo(to.Elem()) {
ekey := fmt.Sprintf("%v[%v] value", key, k.Interface())
var err FieldError
if entry, err = md.adjustValueForAssignment(entry, to.Elem(), ty, ekey); err != nil {
return val, err
}
if !entry.Type().AssignableTo(to.Elem()) {
return val, NewWrongTypeError(ty, ekey, to.Elem(), entry.Type())
}
}
m.SetMapIndex(k, entry)
}
val = m
} else if val.Type() == reflect.TypeOf(emptyObject) {
// The value is an object and needs to be decoded into a value.
obj := val.Interface().(map[string]interface{})
if decode, has := md.opts.CustomDecoders[to]; has {
// A custom decoder exists; use it to unmarshal the type.
target, err := decode(md, obj)
if err != nil {
return val, NewTypeFieldError(ty, key, err)
}
val = reflect.ValueOf(target)
} else if to.Kind() == reflect.Struct || (to.Kind() == reflect.Ptr && to.Elem().Kind() == reflect.Struct) {
// If the target is a struct, we can use the built-in decoding logic.
var target interface{}
if to.Kind() == reflect.Ptr {
target = reflect.New(to.Elem()).Interface()
} else {
target = reflect.New(to).Interface()
}
if err := md.Decode(obj, target); err != nil {
return val, NewTypeFieldError(ty, key, err)
}
val = reflect.ValueOf(target).Elem()
} else {
return val, NewTypeFieldError(ty, key,
fmt.Errorf(
"Cannot decode Object{} to type %v; it isn't a struct, and no custom decoder exists", to))
}
} else if val.Type().Kind() == reflect.String {
// If the source is a string, see if the target implements encoding.TextUnmarshaler.
target := reflect.New(to)
if target.Type().Implements(textUnmarshalerType) {
um := target.Interface().(encoding.TextUnmarshaler)
if err := um.UnmarshalText([]byte(val.String())); err != nil {
return val, NewTypeFieldError(ty, key, err)
}
val = target.Elem()
} else {
break
}
} else {
break
}
}
return val, nil
}