feed/nodeop.go


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package feed

//go:generate stringer -linecomment -type=NodeOp

import (
  "encoding/json"
  "fmt"
)

// Node boolean operator.
type NodeOp byte

const (
  OrOp NodeOp = iota  // OR
  AndOp               // AND
)

// Unmarshal DataVersion from JSON.
func (me *NodeOp) UnmarshalJSON(b []byte) error {
  // decode string, check for error
  var s string
  if err := json.Unmarshal(b, &s); err != nil {
    return err
  }

  // check value
  switch s {
  case "AND":
    *me = AndOp
  case "OR":
    *me = OrOp
  default:
    // return error
    return fmt.Errorf("unknown operator: %s", s)
  }

  // return success
  return nil
}