perf: cache ObjComp allLocals, while-loop sum/avg, arraycopy remove/removeAt

sjsonnet/src/sjsonnet/Evaluator.scala

@@ -1103,7 +1103,7 @@ class Evaluator(
   }
 
   def visitObjComp(e: ObjBody.ObjComp, sup: Val.Obj)(implicit scope: ValScope): Val.Obj = {
-    val binds = e.preLocals ++ e.postLocals
+    val binds = e.allLocals
     val compScope: ValScope = scope // .clearSuper
     val builder = new java.util.LinkedHashMap[String, Val.Obj.Member]
     val compScopes = visitComp(e.first :: e.rest, Array(compScope))

sjsonnet/src/sjsonnet/Expr.scala

@@ -390,6 +390,8 @@ object Expr {
       override def exprErrorString: String = "object comprehension"
       override def toString: String =
         s"ObjComp($pos, ${arrStr(preLocals)}, $key, $value, ${arrStr(postLocals)}, $first, $rest)"
+      // Cache concatenation of preLocals and postLocals to avoid repeated array allocation
+      lazy val allLocals: Array[Bind] = preLocals ++ postLocals
     }
   }
 }

sjsonnet/src/sjsonnet/stdlib/ArrayModule.scala

@@ -487,26 +487,35 @@ object ArrayModule extends AbstractFunctionModule {
       if (idx == -1) {
         arr
       } else {
-        Val.Arr(
-          arr.pos,
-          arr.asLazyArray.slice(0, idx) ++ arr.asLazyArray.slice(idx + 1, arr.length)
-        )
+        val src = arr.asLazyArray
+        val result = new Array[Eval](src.length - 1)
+        System.arraycopy(src, 0, result, 0, idx)
+        System.arraycopy(src, idx + 1, result, idx, src.length - idx - 1)
+        Val.Arr(arr.pos, result)
       }
     },
     builtin("removeAt", "arr", "idx") { (_, _, arr: Val.Arr, idx: Int) =>
       if (!(0 <= idx && idx < arr.length)) {
         Error.fail("index out of bounds: 0 <= " + idx + " < " + arr.length)
       }
-      Val.Arr(
-        arr.pos,
-        arr.asLazyArray.slice(0, idx) ++ arr.asLazyArray.slice(idx + 1, arr.length)
-      )
+      val src = arr.asLazyArray
+      val result = new Array[Eval](src.length - 1)
+      System.arraycopy(src, 0, result, 0, idx)
+      System.arraycopy(src, idx + 1, result, idx, src.length - idx - 1)
+      Val.Arr(arr.pos, result)
     },
     builtin("sum", "arr") { (_, _, arr: Val.Arr) =>
       if (!arr.forall(_.isInstanceOf[Val.Num])) {
         Error.fail("Argument must be an array of numbers")
       }
-      arr.asLazyArray.map(_.value.asDouble).sum
+      val a = arr.asLazyArray
+      var sum = 0.0
+      var i = 0
+      while (i < a.length) {
+        sum += a(i).value.asDouble
+        i += 1
+      }
+      sum
     },
     builtin("avg", "arr") { (_, _, arr: Val.Arr) =>
       if (!arr.forall(_.isInstanceOf[Val.Num])) {
@@ -515,7 +524,14 @@ object ArrayModule extends AbstractFunctionModule {
       if (arr.length == 0) {
         Error.fail("Cannot calculate average of an empty array")
       }
-      arr.asLazyArray.map(_.value.asDouble).sum / arr.length
+      val a = arr.asLazyArray
+      var sum = 0.0
+      var i = 0
+      while (i < a.length) {
+        sum += a(i).value.asDouble
+        i += 1
+      }
+      sum / arr.length
     }
   )
 }