Better parsing of header

vcf/Cargo.toml

@@ -6,3 +6,4 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+regex = "1.9.3"

vcf/src/headers.rs

@@ -48,4 +48,44 @@ mod tests {
             ],
         );
     }
+
+    #[test]
+    fn can_parse_when_quoted_text_contains_comma_in_last_key_value_pair() {
+        let input = "##FORMAT=<abc=123,xyz=3125,sfh=\"1,574\">";
+        let header = Header::parse(input);
+
+        assert_eq!(
+            header,
+            Ok(
+                Header {
+                    key: "FORMAT",
+                    value: HeaderValue::Nested(HashMap::from([
+                        ("abc", "123"),
+                        ("xyz", "3125"),
+                        ("sfh", "1,574"),
+                    ])),
+                }
+            )
+        );
+    }
+
+    #[test]
+    fn can_parse_when_quoted_text_contains_comma_in_first_key_value_pair() {
+        let input = "##FORMAT=<abc=\"1,233\",xyz=3125,sfh=157>";
+        let header = Header::parse(input);
+
+        assert_eq!(
+            header,
+            Ok(
+                Header {
+                    key: "FORMAT",
+                    value: HeaderValue::Nested(HashMap::from([
+                        ("abc", "1,233"),
+                        ("xyz", "3125"),
+                        ("sfh", "157"),
+                    ])),
+                }
+            )
+        );
+    }
 }

vcf/src/parse.rs

@@ -1,5 +1,7 @@
 use std::collections::HashMap;
 
+use regex::Regex;
+
 use crate::{Header, HeaderValue};
 
 impl<'src> Header<'src> {
@@ -15,11 +17,22 @@ impl<'src> Header<'src> {
 
 impl<'src> HeaderValue<'src> {
     pub fn parse(input: &'src str) -> Result<Self, ParseError> {
+        // Repeatedly match either non-comma/non-quote characters or blocks of text enclosed in
+        // quotes, until we can't, in which case we're either at a non-quote-enclosed comma or the
+        // end of the string.
+        let re = Regex::new(r#"(?:[^,"]+|(?:"[^"]*"))+"#).unwrap();
         match input.strip_prefix('<').and_then(|input| input.strip_suffix('>')) {
             None => Ok(Self::Flat(input)),
             Some(pairs) => {
-                pairs.split(',')
+                re.captures_iter(pairs)
+                    .map(|c| c.get(0).unwrap().as_str())
                     .map(|pair| pair.split_once('=').ok_or(ParseError))
+                    .map(
+                        |r| match r {
+                            Ok((k, v)) => Ok((k, v.trim_matches('\"'))),
+                            x => x,
+                        }
+                    )
                     .collect::<Result<HashMap<_, _>, _>>()
                     .map(HeaderValue::Nested)
             }