1// Copyright 2020 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
5package order
6
7import (
8	pref "google.golang.org/protobuf/reflect/protoreflect"
9)
10
11// FieldOrder specifies the ordering to visit message fields.
12// It is a function that reports whether x is ordered before y.
13type FieldOrder func(x, y pref.FieldDescriptor) bool
14
15var (
16	// AnyFieldOrder specifies no specific field ordering.
17	AnyFieldOrder FieldOrder = nil
18
19	// LegacyFieldOrder sorts fields in the same ordering as emitted by
20	// wire serialization in the github.com/golang/protobuf implementation.
21	LegacyFieldOrder FieldOrder = func(x, y pref.FieldDescriptor) bool {
22		ox, oy := x.ContainingOneof(), y.ContainingOneof()
23		inOneof := func(od pref.OneofDescriptor) bool {
24			return od != nil && !od.IsSynthetic()
25		}
26
27		// Extension fields sort before non-extension fields.
28		if x.IsExtension() != y.IsExtension() {
29			return x.IsExtension() && !y.IsExtension()
30		}
31		// Fields not within a oneof sort before those within a oneof.
32		if inOneof(ox) != inOneof(oy) {
33			return !inOneof(ox) && inOneof(oy)
34		}
35		// Fields in disjoint oneof sets are sorted by declaration index.
36		if ox != nil && oy != nil && ox != oy {
37			return ox.Index() < oy.Index()
38		}
39		// Fields sorted by field number.
40		return x.Number() < y.Number()
41	}
42
43	// NumberFieldOrder sorts fields by their field number.
44	NumberFieldOrder FieldOrder = func(x, y pref.FieldDescriptor) bool {
45		return x.Number() < y.Number()
46	}
47
48	// IndexNameFieldOrder sorts non-extension fields before extension fields.
49	// Non-extensions are sorted according to their declaration index.
50	// Extensions are sorted according to their full name.
51	IndexNameFieldOrder FieldOrder = func(x, y pref.FieldDescriptor) bool {
52		// Non-extension fields sort before extension fields.
53		if x.IsExtension() != y.IsExtension() {
54			return !x.IsExtension() && y.IsExtension()
55		}
56		// Extensions sorted by fullname.
57		if x.IsExtension() && y.IsExtension() {
58			return x.FullName() < y.FullName()
59		}
60		// Non-extensions sorted by declaration index.
61		return x.Index() < y.Index()
62	}
63)
64
65// KeyOrder specifies the ordering to visit map entries.
66// It is a function that reports whether x is ordered before y.
67type KeyOrder func(x, y pref.MapKey) bool
68
69var (
70	// AnyKeyOrder specifies no specific key ordering.
71	AnyKeyOrder KeyOrder = nil
72
73	// GenericKeyOrder sorts false before true, numeric keys in ascending order,
74	// and strings in lexicographical ordering according to UTF-8 codepoints.
75	GenericKeyOrder KeyOrder = func(x, y pref.MapKey) bool {
76		switch x.Interface().(type) {
77		case bool:
78			return !x.Bool() && y.Bool()
79		case int32, int64:
80			return x.Int() < y.Int()
81		case uint32, uint64:
82			return x.Uint() < y.Uint()
83		case string:
84			return x.String() < y.String()
85		default:
86			panic("invalid map key type")
87		}
88	}
89)
90