From 2957e913c0d0e7b0565bfcb8af21409648aa5822 Mon Sep 17 00:00:00 2001
From: Camden Dixie O'Brien <cdo@wip.sh>
Date: Fri, 25 Oct 2024 11:31:21 +0100
Subject: [PATCH] Create README with grammar spec

---
 README | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 README

diff --git a/README b/README
new file mode 100644
index 0000000..c74d2a0
--- /dev/null
+++ b/README
@@ -0,0 +1,18 @@
+                             REGEX ENGINE
+
+I've thought for a while it would be fun and interesting to write my
+own regular expression engine using Thompson's construction algorithm,
+so here we are.
+
+                               Grammar
+
+This engine is not going to be strictly supporting any standard
+syntax; the expression syntax I intend to support follows.
+
+	regex ::= sequence ( '|' regex )?
+	sequence ::= term+
+	term ::= ( '.' | class | literal | '(' regex ')' ) quantifier?
+	class ::= '[' '^'? literal+ ']'
+	literal ::= non-special | '\' special
+	quantifier ::= '*' | '+' | '?'
+	special ::= quantifier | '|' | '(' | ')' | '[' | ']' | '^' | '\'