From c1eae9fa3490fc71c7557a20c7bab83f99b0450a Mon Sep 17 00:00:00 2001
From: Brandon Dyck <brandon@dyck.us>
Date: Tue, 10 Sep 2024 19:00:44 -0600
Subject: [PATCH] Added End parser

---
 gigaparsec.go  | 19 +++++++++++++++++++
 parser_test.go |  4 ++++
 2 files changed, 23 insertions(+)

diff --git a/gigaparsec.go b/gigaparsec.go
index 1d2eaf8..5122b95 100644
--- a/gigaparsec.go
+++ b/gigaparsec.go
@@ -222,3 +222,22 @@ func Map[In, Out1, Out2 any](p Parser[In, Out1], f func(Out1) Out2) Parser[In, O
 		return Return[In](f(out))
 	})
 }
+
+func End[In any](s State[In]) (consumed bool, reply Result[In, struct{}], err error) {
+	_, _, err = s.cursor.Read([]In{})
+	if errors.Is(err, io.EOF) {
+		reply := Result[In, struct{}]{
+			State:   s,
+			Message: MessageOK(s.Pos()),
+		}
+		return true, reply, nil
+	}
+	if err != nil {
+		return false, Result[In, struct{}]{}, fmt.Errorf("End: unexpected error: %w", err)
+	}
+	return false, Result[In, struct{}]{}, ParseError{
+		Pos:      s.Pos(),
+		Got:      "",
+		Expected: []string{"end of input"},
+	}
+}
diff --git a/parser_test.go b/parser_test.go
index 7e4e54d..88f8912 100644
--- a/parser_test.go
+++ b/parser_test.go
@@ -90,3 +90,7 @@ func Try(t *testing.T) {
 func TestLabel(t *testing.T) {
 	Todo(t)
 }
+
+func TestEnd(t *testing.T) {
+	Todo(t)
+}