|
| 1 | +package logfmt |
| 2 | + |
| 3 | +import ( |
| 4 | + "fmt" |
| 5 | + "io" |
| 6 | + "reflect" |
| 7 | + "strconv" |
| 8 | + "unicode" |
| 9 | +) |
| 10 | + |
| 11 | +type Encoder struct { |
| 12 | + w io.Writer |
| 13 | + FormatKey func(key string) string |
| 14 | + // FormatPrimitiveValue is used to format primitive values (strings, ints, |
| 15 | + // floats, etc). It is not used for arrays or objects. |
| 16 | + FormatPrimitiveValue func(value interface{}) string |
| 17 | +} |
| 18 | + |
| 19 | +func NewEncoder(w io.Writer) *Encoder { |
| 20 | + return &Encoder{ |
| 21 | + FormatKey: func(key string) string { return key }, |
| 22 | + FormatPrimitiveValue: func(value interface{}) string { return fmt.Sprintf("%+v", value) }, |
| 23 | + w: w, |
| 24 | + } |
| 25 | +} |
| 26 | + |
| 27 | +func isPrimitive(typ reflect.Type) bool { |
| 28 | + switch typ.Kind() { |
| 29 | + case reflect.Bool: |
| 30 | + return true |
| 31 | + case reflect.String: |
| 32 | + return true |
| 33 | + case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: |
| 34 | + return true |
| 35 | + case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64: |
| 36 | + return true |
| 37 | + case reflect.Float32, reflect.Float64: |
| 38 | + return true |
| 39 | + case reflect.Complex64, reflect.Complex128: |
| 40 | + return true |
| 41 | + default: |
| 42 | + return false |
| 43 | + } |
| 44 | +} |
| 45 | + |
| 46 | +// Encode encodes the given message to the writer. For flat objects, the |
| 47 | +// output resembles key=value pairs. For nested objects, a surrounding { } is |
| 48 | +// used. For arrays, a surrounding [ ] is used. |
| 49 | +func (e *Encoder) Encode(m interface{}) error { |
| 50 | + typ := reflect.TypeOf(m) |
| 51 | + if typ.Kind() == reflect.Ptr { |
| 52 | + typ = typ.Elem() |
| 53 | + } |
| 54 | + |
| 55 | + if isPrimitive(typ) { |
| 56 | + e.w.Write([]byte(e.FormatPrimitiveValue(m))) |
| 57 | + return nil |
| 58 | + } |
| 59 | + |
| 60 | + switch typ.Kind() { |
| 61 | + case reflect.Struct: |
| 62 | + v := reflect.ValueOf(m) |
| 63 | + for i := 0; i < typ.NumField(); i++ { |
| 64 | + field := typ.Field(i) |
| 65 | + value := v.Field(i) |
| 66 | + if !value.CanInterface() { |
| 67 | + continue |
| 68 | + } |
| 69 | + if value.IsZero() { |
| 70 | + continue |
| 71 | + } |
| 72 | + if field.Anonymous { |
| 73 | + if err := e.Encode(value.Interface()); err != nil { |
| 74 | + return err |
| 75 | + } |
| 76 | + continue |
| 77 | + } |
| 78 | + if e.FormatKey != nil { |
| 79 | + e.w.Write([]byte(e.FormatKey(field.Name))) |
| 80 | + } else { |
| 81 | + e.w.Write([]byte(field.Name)) |
| 82 | + } |
| 83 | + e.w.Write([]byte("=")) |
| 84 | + if e.FormatPrimitiveValue != nil { |
| 85 | + e.w.Write([]byte(e.FormatPrimitiveValue(value.Interface()))) |
| 86 | + } else { |
| 87 | + e.w.Write([]byte(formatValue(value.Interface()))) |
| 88 | + } |
| 89 | + default: |
| 90 | + return fmt.Errorf("unsupported type %T", m) |
| 91 | + } |
| 92 | +} |
| 93 | + |
| 94 | +// quotes quotes a string so that it is suitable |
| 95 | +// as a key for a map or in general some output that |
| 96 | +// cannot span multiple lines or have weird characters. |
| 97 | +func quote(key string) string { |
| 98 | + // strconv.Quote does not quote an empty string so we need this. |
| 99 | + if key == "" { |
| 100 | + return `""` |
| 101 | + } |
| 102 | + |
| 103 | + var hasSpace bool |
| 104 | + for _, r := range key { |
| 105 | + if unicode.IsSpace(r) { |
| 106 | + hasSpace = true |
| 107 | + break |
| 108 | + } |
| 109 | + } |
| 110 | + quoted := strconv.Quote(key) |
| 111 | + // If the key doesn't need to be quoted, don't quote it. |
| 112 | + // We do not use strconv.CanBackquote because it doesn't |
| 113 | + // account tabs. |
| 114 | + if !hasSpace && quoted[1:len(quoted)-1] == key { |
| 115 | + return key |
| 116 | + } |
| 117 | + return quoted |
| 118 | +} |
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