From f929f4ffff136689b0acd2e0e81f71fa448b9aae Mon Sep 17 00:00:00 2001
From: Aneurin Barker Snook <a@aneur.in>
Date: Fri, 13 Oct 2023 21:16:08 +0100
Subject: [PATCH] add slice size validation

---
 size.go | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)
 create mode 100644 size.go

diff --git a/size.go b/size.go
new file mode 100644
index 0000000..8afe495
--- /dev/null
+++ b/size.go
@@ -0,0 +1,31 @@
+package validate
+
+import (
+	"errors"
+)
+
+// Validation error.
+var (
+	ErrTooFewItems  = errors.New("too few items")
+	ErrTooManyItems = errors.New("too many items")
+)
+
+// MaxSize validates the length of a slice as being less than or equal to a given maximum.
+func MaxSize[T any](l int) func([]T) error {
+	return func(value []T) error {
+		if len(value) > l {
+			return ErrTooFewItems
+		}
+		return nil
+	}
+}
+
+// MinSize validates the length of a slice as being greater than or equal to a given minimum.
+func MinSize[T any](l int) func([]T) error {
+	return func(value []T) error {
+		if len(value) < l {
+			return ErrTooManyItems
+		}
+		return nil
+	}
+}