118 lines
2.5 KiB
Go
118 lines
2.5 KiB
Go
package envconfig
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import (
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"fmt"
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"reflect"
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"strconv"
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"strings"
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)
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/*
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ignored:"true"
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env:"ENVIRONMENT_VARIABLE"
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default:"default value"
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*/
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type StructInfo struct {
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Name string
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Alt string
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Key string
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Field reflect.Value
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Tags reflect.StructTag
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Type reflect.Type
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DefaultValue interface{}
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}
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func GetStructInfo(spec interface{}) ([]StructInfo, error) {
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s := reflect.ValueOf(spec)
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if s.Kind() != reflect.Pointer {
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return []StructInfo{}, fmt.Errorf("getStructInfo() was sent a %s instead of a pointer to a struct.\n", s.Kind())
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}
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s = s.Elem()
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if s.Kind() != reflect.Struct {
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return []StructInfo{}, fmt.Errorf("getStructInfo() was sent a %s instead of a struct.\n", s.Kind())
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}
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typeOfSpec := s.Type()
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infos := make([]StructInfo, 0, s.NumField())
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for i := 0; i < s.NumField(); i++ {
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f := s.Field(i)
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ftype := typeOfSpec.Field(i)
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ignored, _ := strconv.ParseBool(ftype.Tag.Get("ignored"))
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if !f.CanSet() || ignored {
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continue
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}
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for f.Kind() == reflect.Pointer {
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if f.IsNil() {
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if f.Type().Elem().Kind() != reflect.Struct {
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break
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}
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f.Set(reflect.New(f.Type().Elem()))
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}
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f = f.Elem()
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}
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info := StructInfo{
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Name: ftype.Name,
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Alt: strings.ToUpper(ftype.Tag.Get("env")),
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Key: ftype.Name,
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Field: f,
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Tags: ftype.Tag,
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Type: ftype.Type,
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}
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if info.Alt != "" {
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info.Key = info.Alt
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}
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info.Key = strings.ToUpper(info.Key)
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if ftype.Tag.Get("default") != "" {
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v, err := typeConversion(ftype.Type.String(), ftype.Tag.Get("default"))
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if err != nil {
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return []StructInfo{}, err
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}
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info.DefaultValue = v
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}
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infos = append(infos, info)
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}
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return infos, nil
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}
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func typeConversion(t, v string) (interface{}, error) {
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switch t {
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case "string":
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return v, nil
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case "int":
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return strconv.ParseInt(v, 10, 0)
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case "int8":
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return strconv.ParseInt(v, 10, 8)
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case "int16":
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return strconv.ParseInt(v, 10, 16)
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case "int32":
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return strconv.ParseInt(v, 10, 32)
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case "int64":
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return strconv.ParseInt(v, 10, 64)
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case "uint":
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return strconv.ParseUint(v, 10, 0)
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case "uint16":
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return strconv.ParseUint(v, 10, 16)
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case "uint32":
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return strconv.ParseUint(v, 10, 32)
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case "uint64":
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return strconv.ParseUint(v, 10, 64)
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case "float32":
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return strconv.ParseFloat(v, 32)
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case "float64":
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return strconv.ParseFloat(v, 64)
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case "complex64":
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return strconv.ParseComplex(v, 64)
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case "complex128":
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return strconv.ParseComplex(v, 128)
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case "bool":
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return strconv.ParseBool(v)
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}
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return nil, fmt.Errorf("Unable to identify type.")
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}
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