From 356730208b8b909a9959272e99b1a79c0246cb63 Mon Sep 17 00:00:00 2001
From: Stefan Majewsky <majewsky@gmx.net>
Date: Fri, 17 Jul 2026 19:03:48 +0200
Subject: add type Selection

---
 runtimeindex.go | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

(limited to 'runtimeindex.go')

diff --git a/runtimeindex.go b/runtimeindex.go
index a5f1f67..394c6a8 100644
--- a/runtimeindex.go
+++ b/runtimeindex.go
@@ -29,11 +29,13 @@ func (i RuntimeIndex[R, K]) Index(records []R) map[K]R {
 
 // IndexFrom is like Index, but can directly wrap a [Store.Select] or [Store.SelectWhere] call.
 // If there is an error, it is passed through unchanged.
-func (i RuntimeIndex[R, K]) IndexFrom(records []R, err error) (map[K]R, error) {
-	if err != nil {
-		return nil, err
-	}
-	return i.Index(records), nil
+func (i RuntimeIndex[R, K]) IndexFrom(s Selection[R]) (map[K]R, error) {
+	result := make(map[K]R)
+	err := s.Foreach(func(record R) error {
+		result[i(record)] = record
+		return nil
+	})
+	return result, err
 }
 
 // Partition builds a partition of the resulting records by their index value.
@@ -49,9 +51,12 @@ func (i RuntimeIndex[R, K]) Partition(records []R) map[K][]R {
 
 // PartitionFrom is like Partition, but can directly wrap a [Store.Select] or [Store.SelectWhere] call.
 // If there is an error, it is passed through unchanged.
-func (i RuntimeIndex[R, K]) PartitionFrom(records []R, err error) (map[K][]R, error) {
-	if err != nil {
-		return nil, err
-	}
-	return i.Partition(records), nil
+func (i RuntimeIndex[R, K]) PartitionFrom(s Selection[R]) (map[K][]R, error) {
+	result := make(map[K][]R)
+	err := s.Foreach(func(record R) error {
+		key := i(record)
+		result[key] = append(result[key], record)
+		return nil
+	})
+	return result, err
 }
-- 
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