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