mpagenko | af80163 | 2020-07-03 10:00:42 +0000 | [diff] [blame] | 1 | // Copyright 2019 The Go Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | // Package fieldsort defines an ordering of fields. |
| 6 | // |
| 7 | // The ordering defined by this package matches the historic behavior of the proto |
| 8 | // package, placing extensions first and oneofs last. |
| 9 | // |
| 10 | // There is no guarantee about stability of the wire encoding, and users should not |
| 11 | // depend on the order defined in this package as it is subject to change without |
| 12 | // notice. |
| 13 | package fieldsort |
| 14 | |
| 15 | import ( |
| 16 | "google.golang.org/protobuf/reflect/protoreflect" |
| 17 | ) |
| 18 | |
| 19 | // Less returns true if field a comes before field j in ordered wire marshal output. |
| 20 | func Less(a, b protoreflect.FieldDescriptor) bool { |
| 21 | ea := a.IsExtension() |
| 22 | eb := b.IsExtension() |
| 23 | oa := a.ContainingOneof() |
| 24 | ob := b.ContainingOneof() |
| 25 | switch { |
| 26 | case ea != eb: |
| 27 | return ea |
| 28 | case oa != nil && ob != nil: |
| 29 | if oa == ob { |
| 30 | return a.Number() < b.Number() |
| 31 | } |
| 32 | return oa.Index() < ob.Index() |
| 33 | case oa != nil && !oa.IsSynthetic(): |
| 34 | return false |
| 35 | case ob != nil && !ob.IsSynthetic(): |
| 36 | return true |
| 37 | default: |
| 38 | return a.Number() < b.Number() |
| 39 | } |
| 40 | } |