"MockK: intentions" example about composite matchers

CompositeMatcher.kt

/**
 * Boolean logic "AND" and "OR" matcher composed of two other matchers
 */
data class AndOrMatcher<T : Any>(
    val and: Boolean,
    val first: T,
    val second: T
) : Matcher<T>, CompositeMatcher<T>, CapturingMatcher {
    override val operandValues: List<T>
        get() = listOf(first, second)

    override var subMatchers: List<Matcher<T>>? = null

    override fun match(arg: T?): Boolean =
        if (and)
            subMatchers!![0].match(arg) && subMatchers!![1].match(arg)
        else
            subMatchers!![0].match(arg) || subMatchers!![1].match(arg)

    override fun substitute(map: Map<Any, Any>): Matcher<T> {
        val matcher = copy(
            first = first.internalSubstitute(map),
            second = second.internalSubstitute(map)
        )
        val sm = subMatchers
        if (sm != null) {
            matcher.subMatchers = sm.map { it.substitute(map) }
        }
        return matcher
    }

    override fun capture(arg: Any?) {
        captureSubMatchers(arg)
    }

    override fun toString(): String {
        val sm = subMatchers
        val op = if (and) "and" else "or"
        return if (sm != null)
            "$op(${sm[0]}, ${sm[1]})"
        else
            "$op()"
    }


}