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// Copyright 2019 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package proto
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import (
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	"reflect"
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	"google.golang.org/protobuf/reflect/protoreflect"
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)
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// Equal reports whether two messages are equal,
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// by recursively comparing the fields of the message.
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//
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//   - Bytes fields are equal if they contain identical bytes.
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//     Empty bytes (regardless of nil-ness) are considered equal.
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//
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//   - Floating-point fields are equal if they contain the same value.
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//     Unlike the == operator, a NaN is equal to another NaN.
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//
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//   - Other scalar fields are equal if they contain the same value.
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//
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//   - Message fields are equal if they have
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//     the same set of populated known and extension field values, and
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//     the same set of unknown fields values.
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//
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//   - Lists are equal if they are the same length and
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//     each corresponding element is equal.
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//
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//   - Maps are equal if they have the same set of keys and
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//     the corresponding value for each key is equal.
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//
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// An invalid message is not equal to a valid message.
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// An invalid message is only equal to another invalid message of the
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// same type. An invalid message often corresponds to a nil pointer
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// of the concrete message type. For example, (*pb.M)(nil) is not equal
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// to &pb.M{}.
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// If two valid messages marshal to the same bytes under deterministic
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// serialization, then Equal is guaranteed to report true.
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func Equal(x, y Message) bool {
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	if x == nil || y == nil {
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		return x == nil && y == nil
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	}
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	if reflect.TypeOf(x).Kind() == reflect.Ptr && x == y {
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		// Avoid an expensive comparison if both inputs are identical pointers.
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		return true
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	}
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	mx := x.ProtoReflect()
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	my := y.ProtoReflect()
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	if mx.IsValid() != my.IsValid() {
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		return false
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	}
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	vx := protoreflect.ValueOfMessage(mx)
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	vy := protoreflect.ValueOfMessage(my)
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	return vx.Equal(vy)
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}
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