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val X = Parser("1211") { it.toStack() }
val A1 = parseStream.IsSequenceOnce("1")
val B1 = parseStream.IsSequenceOnce("2")
val list1 = A1 and B1;
val list2 = A1 and A1;
val list3 = list2 or B1;
val lists = list1 and list3
// (A and B) and ( (A and A) or B)
// (1 && 2) && ( (1 && 1) || 2)
// will match 1211
// left 1211
// list 1: 12 > match 12
// left: 11
// list2: 11||2 > match 11
// left: null

    inner class Types {
        var AND = 0;
        var OR = 1;
        var once: IsSequenceOnce? = null
        var oneOrMany: IsSequenceOneOrMany? = null
        var zeroOrMany: IsSequenceZeroOrMany? = null
        var type: Int? = null;
        fun get(): Any? = when {
            once != null -> once
            oneOrMany != null -> oneOrMany
            zeroOrMany != null -> zeroOrMany
            else -> null
        }
        fun add(p: Any, type: Int) {
            this.type = type
            when(p) {
                is IsSequenceOnce -> once = p
                is IsSequenceOneOrMany -> oneOrMany = p
                is IsSequenceZeroOrMany -> zeroOrMany = p
                else -> println("unsupported type")
            }
        }
    }

    inner class Multi(str: String) {
        private val parent = this@Parser
        var list: MutableList<Types> = mutableListOf()
        val value: String = str

        fun printList() = list.forEach {
            val x = it.get()
            println("it.${when(x) {
                is IsSequenceOnce -> "once.value = " + x.value + " as IsSequenceOnce"
                is IsSequenceOneOrMany -> "oneOrMany.value = " + x.value + " as IsSequenceOneOrMany"
                else -> "zeroOrMany.value = " + (x as IsSequenceZeroOrMany).value + " as IsSequenceZeroOrMany"
            }}")
        }

        override fun toString(): String {
            val x = cloneList(list).iterator()
            val result = StringBuilder()
            while (x.hasNext()) {
                val y = x.next().get()
                if (
                    when(y) {
                        is IsSequenceOnce -> y.peek()
                        is IsSequenceOneOrMany -> y.peek()
                        else -> (y as IsSequenceZeroOrMany).peek() 
                    }
                ) {
                    val z = when(y) {
                        is IsSequenceOnce -> y.toString()
                        is IsSequenceOneOrMany -> y.toString()
                        else -> (y as IsSequenceZeroOrMany).toString()
                    }
                    if (
                        when(y) {
                            is IsSequenceOnce -> y.pop()
                            is IsSequenceOneOrMany -> y.pop()
                            else -> (y as IsSequenceZeroOrMany).pop()
                        }
                    ) result.append(z)
                    else break
                } else break
            }
            return result.toString()
        }

        fun peek(): Boolean {
            val x = cloneList(list).iterator()
            var m = 0
            val max = list.size
            while (x.hasNext()) {
                val y = x.next().get()
                if (
                    when(y) {
                        is IsSequenceOnce -> y.peek()
                        is IsSequenceOneOrMany -> y.peek()
                        else -> (y as IsSequenceZeroOrMany).peek()
                    }
                ) {
                    if (
                        when(y) {
                            is IsSequenceOnce -> y.pop()
                            is IsSequenceOneOrMany -> y.pop()
                            else -> (y as IsSequenceZeroOrMany).pop()
                        }
                    ) m++
                    else break
                } else break
            }
            if (m == max) return true
            return false
        }

        fun pop(): Boolean {
            val x = list.iterator()
            var m = 0
            val max = list.size
            while (x.hasNext()) {
                val y = x.next().get()
                if (
                    when(y) {
                        is IsSequenceOnce -> y.peek()
                        is IsSequenceOneOrMany -> y.peek()
                        else -> (y as IsSequenceZeroOrMany).peek()
                    }
                ) {
                    if (
                        when(y) {
                            is IsSequenceOnce -> y.pop()
                            is IsSequenceOneOrMany -> y.pop()
                            else -> (y as IsSequenceZeroOrMany).pop()
                        }
                    ) m++
                    else break
                } else break
            }
            if (m == max) return true
            return false
        }

        infix fun and(right: Multi): Multi {
            val x = parent.clone().Multi(this.value)
            x.list.addAll(this.list)
            x.list.addAll(right.list)
            return x
        }

        infix fun and(right: IsSequenceZeroOrMany): Multi {
            val x = parent.clone().Multi(this.value)
            x.list.addAll(this.list)
            if (right.list.size != 0) x.list.addAll(right.list) else x.list.add(Types().also { it.add(right, it.AND) })
            return x
        }

        infix fun and(right: IsSequenceOneOrMany): Multi {
            val x = parent.clone().Multi(this.value)
            x.list.addAll(this.list)
            if (right.list.size != 0) x.list.addAll(right.list) else x.list.add(Types().also { it.add(right, it.AND) })
            return x
        }

        infix fun and(right: IsSequenceOnce): Multi {
            val x = parent.clone().Multi(this.value)
            x.list.addAll(this.list)
            if (right.list.size != 0) x.list.addAll(right.list) else x.list.add(Types().also { it.add(right, it.AND) })
            return x
        }
    }

    /**
     * matches a sequence of **str**
     *
     * this is the base class of which all Parser sequence classes use
     *
     * based on [Stack] functions [toString][Stack.toString], [peek][Stack.peek], and
     * [pop][Stack.pop]
     *
     * @param str a string to match
     * @see IsSequenceZeroOrMany
     * @see IsSequenceOneOrMany
     */
    inner class IsSequenceOnce(str: String) {
        val parent = this@Parser
        var list: MutableList<Types> = mutableListOf()
        var type: Int? = null

        fun printList() = list.forEach {
            val x = it.get()
            println("it.${when(x) {
                is IsSequenceOnce -> "once.value = " + x.value + " as IsSequenceOnce"
                is IsSequenceOneOrMany -> "oneOrMany.value = " + x.value + " as IsSequenceOneOrMany"
                else -> "zeroOrMany.value = " + (x as IsSequenceZeroOrMany).value + " as IsSequenceZeroOrMany"
            }}")
        }

        /**
         * the string to match
         */
        val value = str

        /**
         * returns the accumulative value of [Parser.peek] and [Parser.pop]
         *
         * the original [tokenList] is [cloned][Parser.clone] to prevent modifications to the original [list][tokenList]
         *
         * @return "" if either [tokenList] or [str][value] is empty
         *
         * otherwise the result of [Parser.peek], which can never be an empty string
         * @see peek
         * @see pop
         */
        override fun toString(): String = if (list.size != 0) toStringMultiple() else toStringSingle()

        private fun toStringSingle(): String {
            val tmp = tokenList.clone()
            val s = stackMethodFunction(value)
            if (s.peek() == null || tmp.peek() == null) return ""
            val result = StringBuilder()
            while (tmp.peek() != null && s.peek() != null) {
                val x = tmp.peek()
                if (tmp.pop() == s.pop()) result.append(x)
            }
            return result.toString()
        }

        private fun toStringMultiple(): String {
            val x = cloneList(list).iterator()
            val result = StringBuilder()
            while (x.hasNext()) {
                val y = x.next().once!!
                if (y.peek()) {
                    result.append(y.toString())
                    y.pop()
                } else break
            }
            return result.toString()
        }

        /**
         * the original [tokenList] is [cloned][Parser.clone] to prevent modifications to the original [list][tokenList]
         *
         * @return false if [str][value] does not match
         *
         * otherwise returns true
         * @see toString
         * @see pop
         */
        fun peek(): Boolean = if (list.size != 0) {
            if (type == Types().AND) peekMultipleAnd()
            else peekMultipleOr()
        } else peekSingle()

        private fun peekSingle(): Boolean {
            val tmp = tokenList.clone()
            val s = stackMethodFunction(value)
            if (s.peek() == null || tmp.peek() == null) return false
            val expected = s.size
            var matches = 0
            while (tmp.peek() != null && s.peek() != null) if (tmp.pop() == s.pop()) matches++
            if (matches == expected) return true
            return false
        }

        private fun peekMultipleAnd(): Boolean {
            val x = cloneList(list).iterator()
            var m = 0
            val max = list.size
            while (x.hasNext()) {
                val p = x.next().once!!
                if (p.peek()) {
                    m++
                    p.pop()
                } else break
            }
            if (m == max) return true
            return false
        }

        private fun peekMultipleOr(): Boolean {
            val x = cloneList(list).iterator()
            while (x.hasNext()) {
                val p = x.next().once!!
                if (p.peek()) {
                    p.pop()
                    return true;
                }
            }
            return false
        }

        /**
         *
         * **WARNING**: this **CAN** modify [tokenList]
         *
         * it is recommended to use ***if (Parser.peek()) Parser.pop()*** to avoid accidental modifications, where
         * **Parser** is an instance of [IsSequenceOnce]
         *
         * @return false if [str][value] does not match
         *
         * otherwise returns true
         * @see toString
         * @see peek
         */
        fun pop(): Boolean = if (list.size != 0) {
            if (type == Types().AND) popMultipleAnd()
            else popMultipleOr()
        } else popSingle()

        private fun popSingle(): Boolean {
            val s = stackMethodFunction(value)
            if (s.peek() == null) return false
            val expected = s.size
            var matches = 0
            while (this@Parser.peek() != null && s.peek() != null) if (this@Parser.pop().equals(s.pop())) matches++
            if (matches == expected) return true
            return false
        }

        private fun popMultipleAnd(): Boolean {
            val x = list.iterator()
            var m = 0
            val max = list.size
            while (x.hasNext()) {
                val y = x.next().once!!
                if (y.peek()) {
                    m++
                    y.pop()
                } else break
            }
            if (m == max) return true
            return false
        }

        private fun popMultipleOr(): Boolean {
            val x = list.iterator()
            while (x.hasNext()) {
                val y = x.next().once!!
                if (y.peek()) {
                    y.pop()
                    return true
                } else break
            }
            return false
        }

        infix fun and(right: IsSequenceZeroOrMany): Multi {
            val x = parent.clone().Multi(this.value)
            if (this.type == null || this.type == Types().AND) x.type = Types().AND
            if (right.type == null || right.type == Types().AND) x.type = Types().AND
            if (this.list.size != 0) x.list.addAll(this.list) else x.list.add(Types().also { it.add(this, it.AND) })
            if (right.list.size != 0) x.list.addAll(right.list) else x.list.add(Types().also { it.add(right, it.AND) })
            return x
        }

        infix fun and(right: IsSequenceOneOrMany): Multi {
            val x = parent.clone().Multi(this.value)
            if (this.type == null || this.type == Types().AND) x.type = Types().AND
            if (right.type == null || right.type == Types().AND) x.type = Types().AND
            if (this.list.size != 0) x.list.addAll(this.list) else x.list.add(Types().also { it.add(this, it.AND) })
            if (right.list.size != 0) x.list.addAll(right.list) else x.list.add(Types().also { it.add(right, it.AND) })
            return x
        }

        infix fun and(right: IsSequenceOnce): IsSequenceOnce {
            val x = parent.clone().IsSequenceOnce(this.value)
            if (this.type == null || this.type == Types().AND) x.type = Types().AND
            if (right.type == null || right.type == Types().AND) x.type = Types().AND
            if (this.list.size != 0) x.list.addAll(this.list) else x.list.add(Types().also { it.add(this, it.AND) })
            if (right.list.size != 0) x.list.addAll(right.list) else x.list.add(Types().also { it.add(right, it.AND) })
            return x
        }

        infix fun or(right: IsSequenceZeroOrMany): Multi {
            val x = parent.clone().Multi(this.value)
            if (this.type == null || this.type == Types().OR) x.type = Types().OR
            if (right.type == null || right.type == Types().OR) x.type = Types().OR
            if (this.list.size != 0) x.list.addAll(this.list) else x.list.add(Types().also { it.add(this, it.OR) })
            if (right.list.size != 0) x.list.addAll(right.list) else x.list.add(Types().also { it.add(right, it.OR) })
            return x
        }

        infix fun or(right: IsSequenceOneOrMany): Multi {
            val x = parent.clone().Multi(this.value)
            if (this.type == null || this.type == Types().OR) x.type = Types().OR
            if (right.type == null || right.type == Types().OR) x.type = Types().OR
            if (this.list.size != 0) x.list.addAll(this.list) else x.list.add(Types().also { it.add(this, it.OR) })
            if (right.list.size != 0) x.list.addAll(right.list) else x.list.add(Types().also { it.add(right, it.OR) })
            return x
        }

        infix fun or(right: IsSequenceOnce): IsSequenceOnce {
            val x = parent.clone().IsSequenceOnce(this.value)
            if (this.type == null || this.type == Types().OR) x.type = Types().OR
            if (right.type == null || right.type == Types().OR) x.type = Types().OR
            if (this.list.size != 0) x.list.addAll(this.list) else x.list.add(Types().also { it.add(this, it.OR) })
            if (right.list.size != 0) x.list.addAll(right.list) else x.list.add(Types().also { it.add(right, it.OR) })
            return x
        }
    }