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1 package encoding |
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2 |
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3 import ( |
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4 "sync" |
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5 ) |
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6 |
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7 // Decoder decodes the contents of b into v. |
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8 // It's primarily used for decoding contents of a file into a map[string]interface{}. |
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9 type Decoder interface { |
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10 Decode(b []byte, v map[string]interface{}) error |
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11 } |
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12 |
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13 const ( |
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14 // ErrDecoderNotFound is returned when there is no decoder registered for a format. |
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15 ErrDecoderNotFound = encodingError("decoder not found for this format") |
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16 |
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17 // ErrDecoderFormatAlreadyRegistered is returned when an decoder is already registered for a format. |
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18 ErrDecoderFormatAlreadyRegistered = encodingError("decoder already registered for this format") |
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19 ) |
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20 |
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21 // DecoderRegistry can choose an appropriate Decoder based on the provided format. |
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22 type DecoderRegistry struct { |
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23 decoders map[string]Decoder |
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24 |
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25 mu sync.RWMutex |
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26 } |
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27 |
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28 // NewDecoderRegistry returns a new, initialized DecoderRegistry. |
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29 func NewDecoderRegistry() *DecoderRegistry { |
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30 return &DecoderRegistry{ |
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31 decoders: make(map[string]Decoder), |
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32 } |
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33 } |
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34 |
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35 // RegisterDecoder registers a Decoder for a format. |
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36 // Registering a Decoder for an already existing format is not supported. |
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37 func (e *DecoderRegistry) RegisterDecoder(format string, enc Decoder) error { |
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38 e.mu.Lock() |
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39 defer e.mu.Unlock() |
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40 |
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41 if _, ok := e.decoders[format]; ok { |
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42 return ErrDecoderFormatAlreadyRegistered |
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43 } |
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44 |
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45 e.decoders[format] = enc |
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46 |
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47 return nil |
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48 } |
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49 |
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50 // Decode calls the underlying Decoder based on the format. |
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51 func (e *DecoderRegistry) Decode(format string, b []byte, v map[string]interface{}) error { |
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52 e.mu.RLock() |
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53 decoder, ok := e.decoders[format] |
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54 e.mu.RUnlock() |
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55 |
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56 if !ok { |
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57 return ErrDecoderNotFound |
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58 } |
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59 |
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60 return decoder.Decode(b, v) |
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61 } |