package hcl import ( "errors" "fmt" "reflect" "sort" "strconv" "strings" "github.com/hashicorp/hcl/hcl/ast" "github.com/hashicorp/hcl/hcl/token" ) // This is the tag to use with structures to have settings for HCL const tagName = "hcl" // Decode reads the given input and decodes it into the structure // given by `out`. func Decode(out interface{}, in string) error { obj, err := Parse(in) if err != nil { return err } return DecodeObject(out, obj) } // DecodeObject is a lower-level version of Decode. It decodes a // raw Object into the given output. func DecodeObject(out interface{}, n ast.Node) error { val := reflect.ValueOf(out) if val.Kind() != reflect.Ptr { return errors.New("result must be a pointer") } // If we have the file, we really decode the root node if f, ok := n.(*ast.File); ok { n = f.Node } var d decoder return d.decode("root", n, val.Elem()) } type decoder struct { stack []reflect.Kind } func (d *decoder) decode(name string, node ast.Node, result reflect.Value) error { k := result // If we have an interface with a valid value, we use that // for the check. if result.Kind() == reflect.Interface { elem := result.Elem() if elem.IsValid() { k = elem } } // Push current onto stack unless it is an interface. if k.Kind() != reflect.Interface { d.stack = append(d.stack, k.Kind()) // Schedule a pop defer func() { d.stack = d.stack[:len(d.stack)-1] }() } switch k.Kind() { case reflect.Bool: return d.decodeBool(name, node, result) case reflect.Float64: return d.decodeFloat(name, node, result) case reflect.Int: return d.decodeInt(name, node, result) case reflect.Interface: // When we see an interface, we make our own thing return d.decodeInterface(name, node, result) case reflect.Map: return d.decodeMap(name, node, result) case reflect.Ptr: return d.decodePtr(name, node, result) case reflect.Slice: return d.decodeSlice(name, node, result) case reflect.String: return d.decodeString(name, node, result) case reflect.Struct: return d.decodeStruct(name, node, result) default: return fmt.Errorf( "%s: unknown kind to decode into: %s", name, k.Kind()) } return nil } func (d *decoder) decodeBool(name string, node ast.Node, result reflect.Value) error { switch n := node.(type) { case *ast.LiteralType: if n.Token.Type == token.BOOL { v, err := strconv.ParseBool(n.Token.Text) if err != nil { return err } result.Set(reflect.ValueOf(v)) return nil } } return fmt.Errorf("%s: unknown type %T", name, node) } func (d *decoder) decodeFloat(name string, node ast.Node, result reflect.Value) error { switch n := node.(type) { case *ast.LiteralType: if n.Token.Type == token.FLOAT { v, err := strconv.ParseFloat(n.Token.Text, 64) if err != nil { return err } result.Set(reflect.ValueOf(v)) return nil } } return fmt.Errorf("%s: unknown type %T", name, node) } func (d *decoder) decodeInt(name string, node ast.Node, result reflect.Value) error { switch n := node.(type) { case *ast.LiteralType: switch n.Token.Type { case token.NUMBER: v, err := strconv.ParseInt(n.Token.Text, 0, 0) if err != nil { return err } result.Set(reflect.ValueOf(int(v))) return nil case token.STRING: v, err := strconv.ParseInt(n.Token.Value().(string), 0, 0) if err != nil { return err } result.Set(reflect.ValueOf(int(v))) return nil } } return fmt.Errorf("%s: unknown type %T", name, node) } func (d *decoder) decodeInterface(name string, node ast.Node, result reflect.Value) error { var set reflect.Value redecode := true // For testing types, ObjectType should just be treated as a list. We // set this to a temporary var because we want to pass in the real node. testNode := node if ot, ok := node.(*ast.ObjectType); ok { testNode = ot.List } switch n := testNode.(type) { case *ast.ObjectList: // If we're at the root or we're directly within a slice, then we // decode objects into map[string]interface{}, otherwise we decode // them into lists. if len(d.stack) == 0 || d.stack[len(d.stack)-1] == reflect.Slice { var temp map[string]interface{} tempVal := reflect.ValueOf(temp) result := reflect.MakeMap( reflect.MapOf( reflect.TypeOf(""), tempVal.Type().Elem())) set = result } else { var temp []map[string]interface{} tempVal := reflect.ValueOf(temp) result := reflect.MakeSlice( reflect.SliceOf(tempVal.Type().Elem()), 0, len(n.Items)) set = result } case *ast.ObjectType: // If we're at the root or we're directly within a slice, then we // decode objects into map[string]interface{}, otherwise we decode // them into lists. if len(d.stack) == 0 || d.stack[len(d.stack)-1] == reflect.Slice { var temp map[string]interface{} tempVal := reflect.ValueOf(temp) result := reflect.MakeMap( reflect.MapOf( reflect.TypeOf(""), tempVal.Type().Elem())) set = result } else { var temp []map[string]interface{} tempVal := reflect.ValueOf(temp) result := reflect.MakeSlice( reflect.SliceOf(tempVal.Type().Elem()), 0, 1) set = result } case *ast.ListType: var temp []interface{} tempVal := reflect.ValueOf(temp) result := reflect.MakeSlice( reflect.SliceOf(tempVal.Type().Elem()), 0, 0) set = result case *ast.LiteralType: switch n.Token.Type { case token.BOOL: var result bool set = reflect.Indirect(reflect.New(reflect.TypeOf(result))) case token.FLOAT: var result float64 set = reflect.Indirect(reflect.New(reflect.TypeOf(result))) case token.NUMBER: var result int set = reflect.Indirect(reflect.New(reflect.TypeOf(result))) case token.STRING, token.HEREDOC: set = reflect.Indirect(reflect.New(reflect.TypeOf(""))) default: return fmt.Errorf( "%s: cannot decode into interface: %T", name, node) } default: return fmt.Errorf( "%s: cannot decode into interface: %T", name, node) } // Set the result to what its supposed to be, then reset // result so we don't reflect into this method anymore. result.Set(set) if redecode { // Revisit the node so that we can use the newly instantiated // thing and populate it. if err := d.decode(name, node, result); err != nil { return err } } return nil } func (d *decoder) decodeMap(name string, node ast.Node, result reflect.Value) error { if item, ok := node.(*ast.ObjectItem); ok { node = &ast.ObjectList{Items: []*ast.ObjectItem{item}} } if ot, ok := node.(*ast.ObjectType); ok { node = ot.List } n, ok := node.(*ast.ObjectList) if !ok { return fmt.Errorf("%s: not an object type for map (%T)", name, node) } // If we have an interface, then we can address the interface, // but not the slice itself, so get the element but set the interface set := result if result.Kind() == reflect.Interface { result = result.Elem() } resultType := result.Type() resultElemType := resultType.Elem() resultKeyType := resultType.Key() if resultKeyType.Kind() != reflect.String { return fmt.Errorf( "%s: map must have string keys", name) } // Make a map if it is nil resultMap := result if result.IsNil() { resultMap = reflect.MakeMap( reflect.MapOf(resultKeyType, resultElemType)) } // Go through each element and decode it. done := make(map[string]struct{}) for _, item := range n.Items { if item.Val == nil { continue } // Get the key we're dealing with, which is the first item keyStr := item.Keys[0].Token.Value().(string) // If we've already processed this key, then ignore it if _, ok := done[keyStr]; ok { continue } // Determine the value. If we have more than one key, then we // get the objectlist of only these keys. itemVal := item.Val if len(item.Keys) > 1 { itemVal = n.Filter(keyStr) done[keyStr] = struct{}{} } // Make the field name fieldName := fmt.Sprintf("%s.%s", name, keyStr) // Get the key/value as reflection values key := reflect.ValueOf(keyStr) val := reflect.Indirect(reflect.New(resultElemType)) // If we have a pre-existing value in the map, use that oldVal := resultMap.MapIndex(key) if oldVal.IsValid() { val.Set(oldVal) } // Decode! if err := d.decode(fieldName, itemVal, val); err != nil { return err } // Set the value on the map resultMap.SetMapIndex(key, val) } // Set the final map if we can set.Set(resultMap) return nil } func (d *decoder) decodePtr(name string, node ast.Node, result reflect.Value) error { // Create an element of the concrete (non pointer) type and decode // into that. Then set the value of the pointer to this type. resultType := result.Type() resultElemType := resultType.Elem() val := reflect.New(resultElemType) if err := d.decode(name, node, reflect.Indirect(val)); err != nil { return err } result.Set(val) return nil } func (d *decoder) decodeSlice(name string, node ast.Node, result reflect.Value) error { // If we have an interface, then we can address the interface, // but not the slice itself, so get the element but set the interface set := result if result.Kind() == reflect.Interface { result = result.Elem() } // Create the slice if it isn't nil resultType := result.Type() resultElemType := resultType.Elem() if result.IsNil() { resultSliceType := reflect.SliceOf(resultElemType) result = reflect.MakeSlice( resultSliceType, 0, 0) } // Figure out the items we'll be copying into the slice var items []ast.Node switch n := node.(type) { case *ast.ObjectList: items = make([]ast.Node, len(n.Items)) for i, item := range n.Items { items[i] = item } case *ast.ObjectType: items = []ast.Node{n} case *ast.ListType: items = n.List default: return fmt.Errorf("unknown slice type: %T", node) } for i, item := range items { fieldName := fmt.Sprintf("%s[%d]", name, i) // Decode val := reflect.Indirect(reflect.New(resultElemType)) if err := d.decode(fieldName, item, val); err != nil { return err } // Append it onto the slice result = reflect.Append(result, val) } set.Set(result) return nil } func (d *decoder) decodeString(name string, node ast.Node, result reflect.Value) error { switch n := node.(type) { case *ast.LiteralType: switch n.Token.Type { case token.NUMBER: result.Set(reflect.ValueOf(n.Token.Text).Convert(result.Type())) return nil case token.STRING, token.HEREDOC: result.Set(reflect.ValueOf(n.Token.Value()).Convert(result.Type())) return nil } } return fmt.Errorf("%s: unknown type for string %T", name, node) } func (d *decoder) decodeStruct(name string, node ast.Node, result reflect.Value) error { var item *ast.ObjectItem if it, ok := node.(*ast.ObjectItem); ok { item = it node = it.Val } if ot, ok := node.(*ast.ObjectType); ok { node = ot.List } list, ok := node.(*ast.ObjectList) if !ok { return fmt.Errorf("%s: not an object type for struct (%T)", name, node) } // This slice will keep track of all the structs we'll be decoding. // There can be more than one struct if there are embedded structs // that are squashed. structs := make([]reflect.Value, 1, 5) structs[0] = result // Compile the list of all the fields that we're going to be decoding // from all the structs. fields := make(map[*reflect.StructField]reflect.Value) for len(structs) > 0 { structVal := structs[0] structs = structs[1:] structType := structVal.Type() for i := 0; i < structType.NumField(); i++ { fieldType := structType.Field(i) if fieldType.Anonymous { fieldKind := fieldType.Type.Kind() if fieldKind != reflect.Struct { return fmt.Errorf( "%s: unsupported type to struct: %s", fieldType.Name, fieldKind) } // We have an embedded field. We "squash" the fields down // if specified in the tag. squash := false tagParts := strings.Split(fieldType.Tag.Get(tagName), ",") for _, tag := range tagParts[1:] { if tag == "squash" { squash = true break } } if squash { structs = append( structs, result.FieldByName(fieldType.Name)) continue } } // Normal struct field, store it away fields[&fieldType] = structVal.Field(i) } } usedKeys := make(map[string]struct{}) decodedFields := make([]string, 0, len(fields)) decodedFieldsVal := make([]reflect.Value, 0) unusedKeysVal := make([]reflect.Value, 0) for fieldType, field := range fields { if !field.IsValid() { // This should never happen panic("field is not valid") } // If we can't set the field, then it is unexported or something, // and we just continue onwards. if !field.CanSet() { continue } fieldName := fieldType.Name tagValue := fieldType.Tag.Get(tagName) tagParts := strings.SplitN(tagValue, ",", 2) if len(tagParts) >= 2 { switch tagParts[1] { case "decodedFields": decodedFieldsVal = append(decodedFieldsVal, field) continue case "key": if item == nil { return fmt.Errorf( "%s: %s asked for 'key', impossible", name, fieldName) } field.SetString(item.Keys[0].Token.Value().(string)) continue case "unusedKeys": unusedKeysVal = append(unusedKeysVal, field) continue } } if tagParts[0] != "" { fieldName = tagParts[0] } // Determine the element we'll use to decode. If it is a single // match (only object with the field), then we decode it exactly. // If it is a prefix match, then we decode the matches. filter := list.Filter(fieldName) prefixMatches := filter.Children() matches := filter.Elem() if len(matches.Items) == 0 && len(prefixMatches.Items) == 0 { continue } // Track the used key usedKeys[fieldName] = struct{}{} // Create the field name and decode. We range over the elements // because we actually want the value. fieldName = fmt.Sprintf("%s.%s", name, fieldName) if len(prefixMatches.Items) > 0 { if err := d.decode(fieldName, prefixMatches, field); err != nil { return err } } for _, match := range matches.Items { var decodeNode ast.Node = match.Val if ot, ok := decodeNode.(*ast.ObjectType); ok { decodeNode = &ast.ObjectList{Items: ot.List.Items} } if err := d.decode(fieldName, decodeNode, field); err != nil { return err } } decodedFields = append(decodedFields, fieldType.Name) } if len(decodedFieldsVal) > 0 { // Sort it so that it is deterministic sort.Strings(decodedFields) for _, v := range decodedFieldsVal { v.Set(reflect.ValueOf(decodedFields)) } } return nil }