From 75de281ceeb73e0cfa23109be6bd1ceb1d128b10 Mon Sep 17 00:00:00 2001
From: Kistaro Windrider <kistaro@gmail.com>
Date: Sat, 1 Apr 2023 19:40:28 -0700
Subject: [PATCH] Refactor Strip (already).

Stripping cards from the Hand will also be useful, so I pulled the logic of Strip out into arrayutil (more efficiently, too) and rewrote deck.Strip to use it.
---
 cardsim/deck.go      | 21 +++------------------
 cardsim/sliceutil.go | 19 +++++++++++++++++++
 2 files changed, 22 insertions(+), 18 deletions(-)

diff --git a/cardsim/deck.go b/cardsim/deck.go
index b888150..627ea70 100644
--- a/cardsim/deck.go
+++ b/cardsim/deck.go
@@ -275,22 +275,7 @@ func (d *Deck[C]) ShuffleBottom(frac float64) error {
 // shouldRemove is provided with each card in the deck and its index.
 // It returns how many cards were stripped from the deck.
 func (d *Deck[C]) Strip(shouldRemove func(idx int, c Card[C]) bool) int {
-	stripped := 0
-	startStripRange := -1
-	for i := 0; i < len(d.cards); i++ {
-		if shouldRemove(i, d.cards[i]) {
-			stripped++
-			if startStripRange < 0 {
-				startStripRange = i
-			}
-		} else if startStripRange >= 0 {
-			d.cards = DeleteNFrom(d.cards, startStripRange, i-startStripRange)
-			i = startStripRange
-			startStripRange = -1
-		}
-	}
-	if startStripRange >= 0 {
-		d.cards = d.cards[:startStripRange]
-	}
-	return stripped
+	origLen := d.Len()
+	d.cards = Strip(d.cards, shouldRemove)
+	return origLen - d.Len()
 }
diff --git a/cardsim/sliceutil.go b/cardsim/sliceutil.go
index e64207e..704731b 100644
--- a/cardsim/sliceutil.go
+++ b/cardsim/sliceutil.go
@@ -126,3 +126,22 @@ func ShufflePart[T any](slice []T, r *rand.Rand, loc, n int) {
 	}
 	ShuffleAll(slice[loc:loc+n], r)
 }
+
+// Strip iterates T, removing any element for which removeWhen returns true
+// (when provided the index of the element and the element itself as arguments).
+// It returns the stripped slice.
+func Strip[T any](slice []T, removeWhen func(idx int, t T) bool) []T {
+	if len(slice) == 0 {
+		return nil
+	}
+	to := 0
+	for from, e := range slice {
+		if !removeWhen(from, e) {
+			if to != from {
+				slice[to] = slice[from]
+			}
+			to++
+		}
+	}
+	return slice[:to]
+}