From 1d62857e14d89b4846d9dd8f15c9fae0e99467f0 Mon Sep 17 00:00:00 2001
From: Alejandro Mery <amery@jpi.io>
Date: Mon, 28 Aug 2023 22:14:45 +0000
Subject: [PATCH] lexer: introduce StateFn and the basic state machine loop

v2: make the error break more explicit

Signed-off-by: Alejandro Mery <amery@jpi.io>
---
 lexer/lexer.go | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/lexer/lexer.go b/lexer/lexer.go
index 33b17b6..e23ecad 100644
--- a/lexer/lexer.go
+++ b/lexer/lexer.go
@@ -1,2 +1,22 @@
 // Package lexer provides basic helpers to implement parsers
 package lexer
+
+// StateFn is a State Function of the parser
+type StateFn func() (StateFn, error)
+
+// Run runs a state machine until the state function either
+// returns nil or an error
+func Run(fn StateFn) error {
+	for fn != nil {
+		var err error
+
+		fn, err = fn()
+		if err != nil {
+			// failed
+			return err
+		}
+	}
+
+	// ended
+	return nil
+}