From eacefbbbe842443efe73a03384c7608390e97cde Mon Sep 17 00:00:00 2001
From: Konstantin Nazarov <mail@knazarov.com>
Date: Sat, 10 Jul 2021 22:45:07 +0000
Subject: [PATCH] Add support for underlined headers

---
 markdown.awk | 26 ++++++++++++++++++++------
 test.sh      | 11 +++++++++++
 2 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/markdown.awk b/markdown.awk
index 7e8708a..9db96c5 100644
--- a/markdown.awk
+++ b/markdown.awk
@@ -3,12 +3,23 @@ BEGIN {
 	in_code = 0
 }
 
-function parse_header(str) {
-	match(str, /#+/);
-    hnum = RLENGTH;
+function parse_header(str,    hnum, content) {
+	if (substr(str, 1, 1) == "#") {
+		match(str, /#+/);
+    	hnum = RLENGTH;
 
-	content = parse_line(substr(str, hnum + 1, length(str) - hnum ));
-	return "<h" hnum ">" content "</h" hnum ">";
+		content = parse_line(substr(str, hnum + 1, length(str) - hnum ));
+		return "<h" hnum ">" content "</h" hnum ">";
+	}
+	if (match(body, /^[^\n]+\n=+$/)) {
+		gsub(/\n=+$/, "", str);
+		return "<h1>" parse_line(str) "</h1>"
+	}
+	if (match(body, /^[^\n]+\n-+$/)) {
+		gsub(/\n-+$/, "", str);
+		return "<h2>" parse_line(str) "</h2>"
+	}
+	return "";
 }
 
 function read_line(str, pos, res, i) {
@@ -254,7 +265,7 @@ function parse_block(str) {
 	if (match(str, /^```\n.*```$/) || match(str, /^    /)) {
 		return parse_code(str);
 	}
-	if (substr(str, 1, 1) == "#") {
+	if (substr(str, 1, 1) == "#" || match(body, /^[^\n]+\n[-=]+$/)) {
 		return parse_header(str);
 	}
 	else if (substr(str, 1, 1) == ">") {
@@ -278,6 +289,9 @@ function line_continues(body, line) {
 	if (match(body, /^#* /))
 		return 0;
 
+	if (match(body, /^[^\n]+\n[-=]+$/))
+		return 0;
+
 	if (line != "")
 		return 1;
 
diff --git a/test.sh b/test.sh
index b1b43a0..9abe49d 100755
--- a/test.sh
+++ b/test.sh
@@ -86,6 +86,17 @@ check <<-EOF
 <h3> Header3</h3>
 EOF
 
+check <<-EOF
+underlined header 1
+===================
+
+underlined header 2
+-------------------
+---
+<h1>underlined header 1</h1>
+<h2>underlined header 2</h2>
+EOF
+
 check <<-EOF
 **bold**
 ---