perf(operators): specialize accuPush comprehension loops

Author: AntonPieper

lib/operators.js

@@ -388,6 +388,10 @@ function runComprehension(items, args, ev, ctx) {
   if (!isArray(items)) items = toIterable(ev, args, items)
   const accu = ev.eval(args.init, (ctx = args.iterCtx.reuse(ctx)))
   ctx.accuValue = accu
+  if (args.step.op === 'accuPush') {
+    if (ctx === args.iterCtx) return iterateLoopAccuPush(ev, ctx, args, items, accu, 0)
+    return continueLoopAccuPush(ev, ctx, args, items, accu, 0)
+  }
   if (ctx === args.iterCtx) return iterateLoop(ev, ctx, args, items, accu, 0)
   return continueLoop(ev, ctx, args, items, accu, 0)
 }
@@ -418,6 +422,34 @@ async function continueLoop(ev, ctx, args, items, accu, i) {
   return args.result(accu)
 }
 
+function iterateLoopAccuPush(ev, ctx, args, items, accu, i) {
+  const condition = args.condition
+  const transform = args.step.args
+  const len = items.length
+  while (i < len) {
+    if (condition && !condition(accu)) break
+    const value = ev.eval(transform, ctx.setIterValue(items[i++], ev))
+    if (value instanceof Promise) return continueLoopAccuPush(ev, ctx, args, items, accu, i, value)
+    accu.push(value)
+  }
+  return args.result(accu)
+}
+
+async function continueLoopAccuPush(ev, ctx, args, items, accu, i, value) {
+  if (ctx === args.iterCtx) ctx.async = true
+  const condition = args.condition
+  const transform = args.step.args
+  const len = items.length
+
+  if (value !== undefined) accu.push(await value)
+  while (i < len) {
+    if (condition && !condition(accu)) return args.result(accu)
+    value = ev.eval(transform, ctx.setIterValue(items[i++], ev))
+    accu.push(value instanceof Promise ? await value : value)
+  }
+  return args.result(accu)
+}
+
 function iterateQuantifier(ev, ctx, args, items, accu, i, error, stp) {
   const condition = args.condition
   const step = args.step