order.go

Documentation: google.golang.org/protobuf/internal/order

     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  	"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 protoreflect.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 protoreflect.FieldDescriptor) bool {
    22  		ox, oy := x.ContainingOneof(), y.ContainingOneof()
    23  		inOneof := func(od protoreflect.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 inOneof(ox) && inOneof(oy) && 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 protoreflect.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 protoreflect.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 protoreflect.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 protoreflect.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
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