improver parser perf

src/main/kotlin/blitz/collections/RefVec.kt

@@ -0,0 +1,111 @@
+package blitz.collections
+
+import kotlin.system.measureTimeMillis
+
+@Suppress("UNCHECKED_CAST")
+class RefVec<T>(private val initCap: Int = 0): Vec<T> {
+    override var size = 0
+    private var cap = initCap
+    private var array: Array<Any?>? = if (initCap > 0) arrayOfNulls(initCap) else null
+
+    override fun clear() {
+        size = 0
+        if (array == null) return
+        if (array!!.size <= initCap) {
+            cap = array!!.size
+        } else {
+            cap = 0
+            array = null
+        }
+    }
+
+    fun copyAsArray(): Array<Any?> =
+        array?.copyOfRange(0, size) ?: emptyArray()
+
+    fun copyIntoArray(arr: Array<Any?>, destOff: Int = 0, startOff: Int = 0) =
+        array?.copyInto(arr, destOff, startOff, size)
+
+    override fun copy(): RefVec<T> =
+        RefVec<T>(size).also {
+            it.array?.let { copyIntoArray(it) }
+        }
+
+    override fun reserve(amount: Int)  {
+        if (amount > 0 && cap - size >= amount)
+            return
+        if (array == null) {
+            cap = size + amount
+            array = arrayOfNulls(cap)
+        } else {
+            array = array!!.copyOf(size + amount)
+            cap = size + amount
+        }
+    }
+
+    override fun reserve(need: Int, totalIfRealloc: Int)  {
+        if (need > 0 && cap - size >= need)
+            return
+        if (array == null) {
+            cap = size + totalIfRealloc
+            array = arrayOfNulls(cap)
+        } else {
+            array = array!!.copyOf(size + totalIfRealloc)
+            cap = size + totalIfRealloc
+        }
+    }
+
+    override fun popBack(): T =
+        array!![size - 1].also {
+            reserve(-1)
+            size --
+        } as T
+
+    override fun get(index: Int): T =
+        array!![index] as T
+
+    override fun flip() {
+        array = array?.reversedArray()
+    }
+
+    override fun pushBack(elem: T) {
+        reserve(1, 8)
+        array!![size] = elem
+        size ++
+    }
+
+    override fun iterator(): Iterator<T> =
+        object : Iterator<T> {
+            var index = 0
+            override fun hasNext(): Boolean = index < size
+            override fun next(): T {
+                if (!hasNext())
+                    throw NoSuchElementException()
+                return array!![index++] as T
+            }
+        }
+
+    override fun toString(): String =
+        joinToString(prefix = "[", postfix = "]") { it.toString() }
+
+    override fun set(index: Int, value: T) {
+        array!![index] = value
+    }
+
+    companion object {
+        fun <T> from(data: Array<T>) =
+            RefVec<T>(data.size).also {
+                it.array?.let { data.copyInto(it) }
+                it.size += data.size
+            }
+
+        fun <T> from(data: Iterable<T>) =
+            RefVec<T>().also { bv ->
+                data.forEach(bv::pushBack)
+            }
+
+        fun <T> of(vararg elements: T): RefVec<T> =
+            RefVec<T>(elements.size).also {
+                it.array?.let { elements.copyInto(it) }
+            }
+    }
+}