elliotchance/gedcom

package gedcom

// NoIndent can be used with GEDCOMLine and GEDCOMString so that the output does
// not contain the indent-levels.
const NoIndent = -1

// GEDCOMLiner allows an instance to return the single-line GEDCOM value as a
// string. This excludes any child nodes.
type GEDCOMLiner interface {
    // GEDCOMLine will return a single GEDCOM line, excluding children and with
    // an optional indent-level.
    //
    // The indent will only be included if it is at least 0. If you want to use
    // GEDCOMLine to compare the string values of nodes or exclude the indent
    // you should use the NoIndent constant.
    //
    // It is not safe to invoke GEDCOMLine on a nil value. Use GEDCOMLine() for
    // a safer alternative.
    GEDCOMLine(indent int) string
}

// GEDCOMStringer allows an instance to be rendered as multi-line GEDCOM.
//
// GEDCOMStringer can be thought of as a superset of GEDCOMLiner, often sharing
// the same line. However, for some entities (such as a Document) it does not
// make sense to implement GEDCOMLiner as well.
type GEDCOMStringer interface {
    // GEDCOMString returns the multi-line GEDCOM that includes an optional
    // indent for each line.
    //
    // The indent will only be included if it is at least 0. If you want to use
    // GEDCOMString to compare the string values of nodes or exclude the indent
    // you should use the NoIndent constant.
    //
    // It is not safe to invoke GEDCOMString on a nil value. Use GEDCOMString()
    // for a safer alternative.
    GEDCOMString(indent int) string
}

// GEDCOMLine is the safer alternative to GEDCOMLiner.GEDCOMLine. It will handle
// nils gracefully, returning an empty string.
func GEDCOMLine(value GEDCOMLiner, indent int) string {
    if IsNil(value) {
        return ""
    }

    return value.GEDCOMLine(indent)
}

// GEDCOMString is the safer alternative to GEDCOMStringer.GEDCOMString. It will
// handle nils gracefully, returning an empty string.
func GEDCOMString(value GEDCOMStringer, indent int) string {
    if IsNil(value) {
        return ""
    }

    return value.GEDCOMString(indent)
}