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Merge pull request #388 from dlorenc/tags
Add yamltags
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,189 @@ | ||
| /* | ||
| Copyright 2018 The Skaffold Authors | ||
| 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 yamltags | ||
|
|
||
| import ( | ||
| "errors" | ||
| "fmt" | ||
| "reflect" | ||
| "strconv" | ||
| "strings" | ||
| ) | ||
|
|
||
| // ProcessStruct validates and processes the provided pointer to a struct. | ||
| func ProcessStruct(s interface{}) error { | ||
| parentStruct := reflect.ValueOf(s).Elem() | ||
| t := parentStruct.Type() | ||
|
|
||
| // Loop through the fields on the struct, looking for tags. | ||
| for i := 0; i < t.NumField(); i++ { | ||
| f := t.Field(i) | ||
| val := parentStruct.Field(i) | ||
| field := parentStruct.Type().Field(i) | ||
| if tags, ok := f.Tag.Lookup("yamltags"); ok { | ||
| if err := ProcessTags(tags, val, parentStruct, field); err != nil { | ||
| return err | ||
| } | ||
| } | ||
| // Recurse down the struct | ||
| if val.Kind() == reflect.Struct { | ||
| if err := ProcessStruct(val.Addr().Interface()); err != nil { | ||
| return err | ||
| } | ||
| } | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| func ProcessTags(yamltags string, val reflect.Value, parentStruct reflect.Value, field reflect.StructField) error { | ||
| tags := strings.Split(yamltags, ",") | ||
| for _, tag := range tags { | ||
| tagParts := strings.Split(tag, "=") | ||
| var yt YamlTag | ||
| switch tagParts[0] { | ||
| case "required": | ||
| yt = &RequiredTag{} | ||
| case "default": | ||
| yt = &DefaultTag{} | ||
| case "oneOf": | ||
| yt = &OneOfTag{ | ||
| Field: field, | ||
| Parent: parentStruct, | ||
| } | ||
| } | ||
| if err := yt.Load(tagParts); err != nil { | ||
| return err | ||
| } | ||
| if err := yt.Process(val); err != nil { | ||
| return err | ||
| } | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| type YamlTag interface { | ||
| Load([]string) error | ||
| Process(reflect.Value) error | ||
| } | ||
|
|
||
| type RequiredTag struct { | ||
| } | ||
|
|
||
| func (rt *RequiredTag) Load(s []string) error { | ||
| return nil | ||
| } | ||
|
|
||
| func (rt *RequiredTag) Process(val reflect.Value) error { | ||
| if isZeroValue(val) { | ||
| return errors.New("required value not set") | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| type DefaultTag struct { | ||
| dv string | ||
| } | ||
|
|
||
| func (dt *DefaultTag) Load(s []string) error { | ||
| if len(s) != 2 { | ||
| return fmt.Errorf("invalid default tag: %v, expected key=value", s) | ||
| } | ||
| dt.dv = s[1] | ||
| return nil | ||
| } | ||
|
|
||
| func (dt *DefaultTag) Process(val reflect.Value) error { | ||
| if !isZeroValue(val) { | ||
| return nil | ||
| } | ||
|
|
||
| switch val.Kind() { | ||
| case reflect.Int, reflect.Int16, reflect.Int32, reflect.Int64: | ||
| i, err := strconv.ParseInt(dt.dv, 0, 0) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| val.SetInt(i) | ||
| case reflect.String: | ||
| val.SetString(dt.dv) | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| // A program can have many structs, that each have many oneOfSets | ||
| // each oneOfSet is a map of a set name to the list of fields that belong to that set | ||
| // only one field in that list can have a non-zero value. | ||
|
|
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| var allOneOfs map[string]map[string][]string | ||
|
|
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| func getOneOfSetsForStruct(structName string) map[string][]string { | ||
| _, ok := allOneOfs[structName] | ||
| if !ok { | ||
| allOneOfs[structName] = map[string][]string{} | ||
| } | ||
| return allOneOfs[structName] | ||
| } | ||
|
|
||
| type OneOfTag struct { | ||
| Field reflect.StructField | ||
| Parent reflect.Value | ||
| oneOfSets map[string][]string | ||
| setName string | ||
| } | ||
|
|
||
| func (oot *OneOfTag) Load(s []string) error { | ||
| if len(s) != 2 { | ||
| return fmt.Errorf("invalid default struct tag: %v, expected key=value", s) | ||
| } | ||
| oot.setName = s[1] | ||
|
|
||
| // Fetch the right oneOfSet for the struct. | ||
| structName := oot.Parent.Type().Name() | ||
| oot.oneOfSets = getOneOfSetsForStruct(structName) | ||
|
|
||
| // Add this field to the oneOfSet | ||
| oot.oneOfSets[oot.setName] = append(oot.oneOfSets[oot.setName], oot.Field.Name) | ||
| return nil | ||
| } | ||
|
|
||
| func (oot *OneOfTag) Process(val reflect.Value) error { | ||
| if isZeroValue(val) { | ||
| return nil | ||
| } | ||
|
|
||
| // This must exist because process is always called after Load. | ||
| oneOfSet := oot.oneOfSets[oot.setName] | ||
| for _, otherField := range oneOfSet { | ||
| if otherField == oot.Field.Name { | ||
| continue | ||
| } | ||
| field := oot.Parent.FieldByName(otherField) | ||
| if !isZeroValue(field) { | ||
| return fmt.Errorf("only one element in set %s can be set. got %s and %s", oot.setName, otherField, oot.Field.Name) | ||
| } | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| func isZeroValue(val reflect.Value) bool { | ||
| zv := reflect.Zero(val.Type()).Interface() | ||
| return reflect.DeepEqual(zv, val.Interface()) | ||
| } | ||
|
|
||
| func init() { | ||
| allOneOfs = make(map[string]map[string][]string) | ||
| } |
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