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 

     5 package order

     6 

     7 import (

     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.

    13 type FieldOrder func(x, y pref.FieldDescriptor) bool

    14 

    15 var (

    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.

    67 type KeyOrder func(x, y pref.MapKey) bool

    68 

    69 var (

    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 )