vcf/io/writer/info/field/value/string: Percent-encode special characters

noodles-vcf/CHANGELOG.md

@@ -7,6 +7,8 @@
   * vcf/io/writer/record: Add validation for IDs, reference bases, alternate
     bases, and filters.
 
+  * vcf/io/writer/info/field/value/string: Percent-encode special characters.
+
 ## 0.52.0 - 2024-04-04
 
 ### Added

noodles-vcf/src/io/writer/record/info/field/value/string.rs

@@ -0,0 +1,45 @@
+use std::io::{self, Write};
+
+use percent_encoding::{utf8_percent_encode, AsciiSet, CONTROLS};
+
+// § 1.2 "Character encoding, non-printable characters and characters with special meaning" (2023-08-23)
+const PERCENT_ENCODE_SET: &AsciiSet = &CONTROLS
+    .add(b':')
+    .add(b';')
+    .add(b'=')
+    .add(b'%')
+    .add(b',')
+    .add(b'\r')
+    .add(b'\n')
+    .add(b'\t');
+
+pub(super) fn write_string<W>(writer: &mut W, s: &str) -> io::Result<()>
+where
+    W: Write,
+{
+    for t in utf8_percent_encode(s, PERCENT_ENCODE_SET) {
+        writer.write_all(t.as_bytes())?;
+    }
+
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_write_string() -> io::Result<()> {
+        let mut buf = Vec::new();
+
+        buf.clear();
+        write_string(&mut buf, "ndls")?;
+        assert_eq!(buf, b"ndls");
+
+        buf.clear();
+        write_string(&mut buf, "noodles=vcf;")?;
+        assert_eq!(buf, b"noodles%3Dvcf%3B");
+
+        Ok(())
+    }
+}