size.go

Documentation: google.golang.org/protobuf/proto

     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 proto
     6  
     7  import (
     8  	"google.golang.org/protobuf/encoding/protowire"
     9  	"google.golang.org/protobuf/internal/encoding/messageset"
    10  	"google.golang.org/protobuf/reflect/protoreflect"
    11  	"google.golang.org/protobuf/runtime/protoiface"
    12  )
    13  
    14  // Size returns the size in bytes of the wire-format encoding of m.
    15  func Size(m Message) int {
    16  	return MarshalOptions{}.Size(m)
    17  }
    18  
    19  // Size returns the size in bytes of the wire-format encoding of m.
    20  func (o MarshalOptions) Size(m Message) int {
    21  	// Treat a nil message interface as an empty message; nothing to output.
    22  	if m == nil {
    23  		return 0
    24  	}
    25  
    26  	return o.size(m.ProtoReflect())
    27  }
    28  
    29  // size is a centralized function that all size operations go through.
    30  // For profiling purposes, avoid changing the name of this function or
    31  // introducing other code paths for size that do not go through this.
    32  func (o MarshalOptions) size(m protoreflect.Message) (size int) {
    33  	methods := protoMethods(m)
    34  	if methods != nil && methods.Size != nil {
    35  		out := methods.Size(protoiface.SizeInput{
    36  			Message: m,
    37  		})
    38  		return out.Size
    39  	}
    40  	if methods != nil && methods.Marshal != nil {
    41  		// This is not efficient, but we don't have any choice.
    42  		// This case is mainly used for legacy types with a Marshal method.
    43  		out, _ := methods.Marshal(protoiface.MarshalInput{
    44  			Message: m,
    45  		})
    46  		return len(out.Buf)
    47  	}
    48  	return o.sizeMessageSlow(m)
    49  }
    50  
    51  func (o MarshalOptions) sizeMessageSlow(m protoreflect.Message) (size int) {
    52  	if messageset.IsMessageSet(m.Descriptor()) {
    53  		return o.sizeMessageSet(m)
    54  	}
    55  	m.Range(func(fd protoreflect.FieldDescriptor, v protoreflect.Value) bool {
    56  		size += o.sizeField(fd, v)
    57  		return true
    58  	})
    59  	size += len(m.GetUnknown())
    60  	return size
    61  }
    62  
    63  func (o MarshalOptions) sizeField(fd protoreflect.FieldDescriptor, value protoreflect.Value) (size int) {
    64  	num := fd.Number()
    65  	switch {
    66  	case fd.IsList():
    67  		return o.sizeList(num, fd, value.List())
    68  	case fd.IsMap():
    69  		return o.sizeMap(num, fd, value.Map())
    70  	default:
    71  		return protowire.SizeTag(num) + o.sizeSingular(num, fd.Kind(), value)
    72  	}
    73  }
    74  
    75  func (o MarshalOptions) sizeList(num protowire.Number, fd protoreflect.FieldDescriptor, list protoreflect.List) (size int) {
    76  	sizeTag := protowire.SizeTag(num)
    77  
    78  	if fd.IsPacked() && list.Len() > 0 {
    79  		content := 0
    80  		for i, llen := 0, list.Len(); i < llen; i++ {
    81  			content += o.sizeSingular(num, fd.Kind(), list.Get(i))
    82  		}
    83  		return sizeTag + protowire.SizeBytes(content)
    84  	}
    85  
    86  	for i, llen := 0, list.Len(); i < llen; i++ {
    87  		size += sizeTag + o.sizeSingular(num, fd.Kind(), list.Get(i))
    88  	}
    89  	return size
    90  }
    91  
    92  func (o MarshalOptions) sizeMap(num protowire.Number, fd protoreflect.FieldDescriptor, mapv protoreflect.Map) (size int) {
    93  	sizeTag := protowire.SizeTag(num)
    94  
    95  	mapv.Range(func(key protoreflect.MapKey, value protoreflect.Value) bool {
    96  		size += sizeTag
    97  		size += protowire.SizeBytes(o.sizeField(fd.MapKey(), key.Value()) + o.sizeField(fd.MapValue(), value))
    98  		return true
    99  	})
   100  	return size
   101  }
   102
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