1// Copyright 2023 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 trace
6
7import "fmt"
8
9// Value is a dynamically-typed value obtained from a trace.
10type Value struct {
11	kind   ValueKind
12	scalar uint64
13}
14
15// ValueKind is the type of a dynamically-typed value from a trace.
16type ValueKind uint8
17
18const (
19	ValueBad ValueKind = iota
20	ValueUint64
21)
22
23// Kind returns the ValueKind of the value.
24//
25// It represents the underlying structure of the value.
26//
27// New ValueKinds may be added in the future. Users of this type must be robust
28// to that possibility.
29func (v Value) Kind() ValueKind {
30	return v.kind
31}
32
33// Uint64 returns the uint64 value for a MetricSampleUint64.
34//
35// Panics if this metric sample's Kind is not MetricSampleUint64.
36func (v Value) Uint64() uint64 {
37	if v.kind != ValueUint64 {
38		panic("Uint64 called on Value of a different Kind")
39	}
40	return v.scalar
41}
42
43// valueAsString produces a debug string value.
44//
45// This isn't just Value.String because we may want to use that to store
46// string values in the future.
47func valueAsString(v Value) string {
48	switch v.Kind() {
49	case ValueUint64:
50		return fmt.Sprintf("Uint64(%d)", v.scalar)
51	}
52	return "Bad"
53}
54