From 5accf50ec467aa14e9dcf7541c2ca0c8ab1a497b Mon Sep 17 00:00:00 2001
From: Sam Anthony <sam@samanthony.xyz>
Date: Sat, 17 Aug 2024 23:12:36 -0400
Subject: ConstSlice

---
 slice.go | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 slice.go

(limited to 'slice.go')

diff --git a/slice.go b/slice.go
new file mode 100644
index 0000000..0be8f3e
--- /dev/null
+++ b/slice.go
@@ -0,0 +1,46 @@
+package share
+
+// ConstSlice is a read-only slice that can be shared between goroutines. It should be closed after use.
+type ConstSlice[T any] struct {
+	requests chan<- chan T
+}
+
+// NewConstSlice initializes a ConstSlice with the given slice. The slice is not copied, and thus should not be used
+// again after creating the ConstSlice.
+func NewConstSlice[T any](slc []T) ConstSlice[T] {
+	requests := make(chan chan T)
+	go serve(slc, requests)
+	return ConstSlice[T]{requests}
+}
+
+// Elems returns a channel that yields each successive element of the slice.
+// Once drained, the channel is closed automatically, and therefore should NOT be closed again by the caller.
+func (cs ConstSlice[T]) Elems() <-chan T {
+	elems := make(chan T) // will be closed by request handler
+	cs.requests <- elems
+	c := make(chan T)
+	go func() {
+		defer close(c)
+		for elem := range elems {
+			c <- elem
+		}
+	}()
+	return c
+}
+
+func (cs ConstSlice[T]) Close() {
+	close(cs.requests)
+}
+
+func serve[T any](slc []T, requests <-chan chan T) {
+	for request := range requests {
+		go handle(request, slc)
+	}
+}
+
+func handle[T any](request chan<- T, slc []T) {
+	defer close(request)
+	for _, v := range slc {
+		request <- v
+	}
+}
-- 
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