Extract shared readFrom helper to deduplicate io.Reader boilerplate

13 types implemented identical offset-based io.Reader patterns with
5-7 lines of copy-and-offset-tracking code each. Extract a shared
readFrom(p, offset, data) helper and reduce each Read() method to a
one-liner delegating to it.

1 files changed, 15 insertions, 0 deletions

diff --git a/hotline/read_helper.go b/hotline/read_helper.go
new file mode 100644
index 0000000..3154a74
--- /dev/null
+++ b/hotline/read_helper.go
@@ -0,0 +1,15 @@
+package hotline
+
+import "io"
+
+// readFrom is a shared helper for types that implement io.Reader via an
+// offset-based copy from a serialized byte slice. It copies bytes from data
+// starting at *offset into p, advances *offset, and returns io.EOF when done.
+func readFrom(p []byte, offset *int, data []byte) (int, error) {
+	if *offset >= len(data) {
+		return 0, io.EOF
+	}
+	n := copy(p, data[*offset:])
+	*offset += n
+	return n, nil
+}