Uses the MacroEvaluator's argument indices IntArray as-is instead of …

…allocating a new List.

src/main/java/com/amazon/ion/impl/macro/Environment.kt

@@ -16,11 +16,10 @@ package com.amazon.ion.impl.macro
 data class Environment private constructor(
     // Any variables found here have to be looked up in [parentEnvironment]
     val arguments: List<Expression>,
-    // TODO: Replace with IntArray
-    val argumentIndices: List<Int>,
+    val argumentIndices: IntArray,
     val parentEnvironment: Environment?,
 ) {
-    fun createChild(arguments: List<Expression>, argumentIndices: List<Int>) = Environment(arguments, argumentIndices, this)
+    fun createChild(arguments: List<Expression>, argumentIndices: IntArray) = Environment(arguments, argumentIndices, this)
 
     override fun toString() = """
         |Environment(
@@ -33,8 +32,8 @@ data class Environment private constructor(
 
     companion object {
         @JvmStatic
-        val EMPTY = Environment(emptyList(), emptyList(), null)
+        val EMPTY = Environment(emptyList(), IntArray(0), null)
         @JvmStatic
-        fun create(arguments: List<Expression>, argumentIndices: List<Int>) = Environment(arguments, argumentIndices, null)
+        fun create(arguments: List<Expression>, argumentIndices: IntArray) = Environment(arguments, argumentIndices, null)
     }
 }

src/main/java/com/amazon/ion/impl/macro/MacroEvaluator.kt

@@ -906,10 +906,10 @@ private fun calculateArgumentIndices(
     encodingExpressions: List<Expression>,
     argsStartInclusive: Int,
     argsEndExclusive: Int
-): List<Int> {
+): IntArray {
     // TODO: For TDL macro invocations, see if we can calculate this during the "compile" step.
     var numArgs = 0
-    val argsIndices = IntArray(macro.signature.size)
+    val argsIndices = IntArray(macro.signature.size) // TODO performance: pool these
     var currentArgIndex = argsStartInclusive
 
     for (p in macro.signature) {
@@ -936,5 +936,5 @@ private fun calculateArgumentIndices(
     if (numArgs > macro.signature.size) {
         throw IonException("Too many arguments. Expected ${macro.signature.size}, but found $numArgs")
     }
-    return argsIndices.toList()
+    return argsIndices
 }