Method shallowDecode

postgres/parser/json/encoded.go:470–521

shallowDecode decodes only the keys of an object, and doesn't decode any elements of an array. It can be used to save a decode-encode cycle for certain operations (say, key deletion).

()

// elements of an array. It can be used to save a decode-encode cycle for
// certain operations (say, key deletion).
func (j *jsonEncoded) shallowDecode() (JSON, error) {
	if dec := j.alreadyDecoded(); dec != nil {
		return dec, nil
	}

	switch j.typ {
	case NumberJSONType, StringJSONType, TrueJSONType, FalseJSONType, NullJSONType:
		return j.decode()
	case ArrayJSONType:
		iter := j.iterArrayValues()
		result := make(jsonArray, j.containerLen)
		for i := 0; i < j.containerLen; i++ {
			entry, next, _, err := iter.nextEncoded()
			if err != nil {
				return nil, err
			}
			result[i], err = newEncoded(entry, next)
			if err != nil {
				return nil, err
			}
		}
		return result, nil
	case ObjectJSONType:
		iter, err := j.iterObject()
		if err != nil {
			return nil, err
		}
		result := make(jsonObject, j.containerLen)
		for i := 0; i < j.containerLen; i++ {
			nextKey, entry, nextValue, _, err := iter.nextEncoded()
			if err != nil {
				return nil, err
			}
			v, err := newEncoded(entry, nextValue)
			if err != nil {
				return nil, err
			}
			result[i] = jsonKeyValuePair{
				k: jsonString(nextKey),
				v: v,
			}
		}
		j.mu.Lock()
		defer j.mu.Unlock()
		if j.mu.cachedDecoded == nil {
			j.mu.cachedDecoded = result
		}
		return result, nil
	default:
		return nil, errors.AssertionFailedf("unknown json type: %v", errors.Safe(j.typ))
	}
}

func (j *jsonEncoded) mustDecode() JSON {
	decoded, err := j.shallowDecode()