flagEnums.kt

package syntax.flagEnums

private val TODO: Nothing
    get() = throw UnsupportedOperationException()

public open class PatternOptions(public val value: Int = 0) {
    // the only meaning declarations
    public object CASE_INSENSITIVE : PatternOptions(0x02)
    public object COMMENTS : PatternOptions(0x04)
    public object MULTILINE : PatternOptions(0x08)

    // boilerplate

    // ?
    public constructor(vararg options: PatternOptions) : this(options.fold(0) { v, value -> v or value.value })

    public fun plus(other: PatternOptions): PatternOptions {
        if (this.value == 0) return other
        if (other.value == 0) return this
        return PatternOptions(this.value or other.value)
    }

    public fun minus(other: PatternOptions): PatternOptions = TODO

    public override fun toString(): String = TODO // TODO: Decompose value, substitute name, join with comma
    public fun name(): String = TODO // TODO: Only defined for singular name
    //TODO: Comparable<PatternOptions>
    //TODO: equality members

    companion object {
        public val values: List<PatternOptions>
            get() = TODO

        // TODO: Decompose names, substitute value, join with +
        public fun valueOf(value: String): PatternOptions = TODO

    }
}

fun testOptions() {
    fun use(options: PatternOptions) {}

    use( PatternOptions() )
    use(PatternOptions.CASE_INSENSITIVE)
    use(PatternOptions.COMMENTS + PatternOptions.CASE_INSENSITIVE)
    use(PatternOptions(PatternOptions.CASE_INSENSITIVE, PatternOptions.MULTILINE))

    // compose from value
    val p1 = PatternOptions(0x0F)
    // maybe val p2 = PatternOptions.valueOf(0x0f)
    val p3 = PatternOptions.valueOf("COMMENTS, CASE_INSENSITIVE")
    // toggle flag off
    val p4 = p3 - PatternOptions.MULTILINE

    // type conversion
    val v1 = p1.value // or toInt() ?
    val n4 = p4.name()
    val s3 = p3.toString()
}