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// Copyright 2013 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package model
import (
"encoding/json"
"fmt"
)
// Value is a generic interface for values resulting from a query evaluation.
type Value interface {
Type() ValueType
String() string
}
func (Matrix) Type() ValueType { return ValMatrix }
func (Vector) Type() ValueType { return ValVector }
func (*Scalar) Type() ValueType { return ValScalar }
func (*String) Type() ValueType { return ValString }
type ValueType int
const (
ValNone ValueType = iota
ValScalar
ValVector
ValMatrix
ValString
)
// MarshalJSON implements json.Marshaler.
func (et ValueType) MarshalJSON() ([]byte, error) {
return json.Marshal(et.String())
}
func (et *ValueType) UnmarshalJSON(b []byte) error {
var s string
if err := json.Unmarshal(b, &s); err != nil {
return err
}
switch s {
case "<ValNone>":
*et = ValNone
case "scalar":
*et = ValScalar
case "vector":
*et = ValVector
case "matrix":
*et = ValMatrix
case "string":
*et = ValString
default:
return fmt.Errorf("unknown value type %q", s)
}
return nil
}
func (e ValueType) String() string {
switch e {
case ValNone:
return "<ValNone>"
case ValScalar:
return "scalar"
case ValVector:
return "vector"
case ValMatrix:
return "matrix"
case ValString:
return "string"
}
panic("ValueType.String: unhandled value type")
}
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