vcf/variant/record: Add info fields trait

noodles-vcf/src/variant/record.rs

@@ -1,3 +1,5 @@
 //! Variant record.
 
 pub mod info;
+
+pub use self::info::Info;

noodles-vcf/src/variant/record/info.rs

@@ -1,3 +1,23 @@
 //! Variant record info fields.
 
 pub mod field;
+
+use std::io;
+
+use self::field::Value;
+use crate::Header;
+
+/// Variant record info fields.
+pub trait Info {
+    /// Returns whether there are any fields.
+    fn is_empty(&self) -> bool;
+
+    /// Returns the number of fields.
+    fn len(&self) -> usize;
+
+    /// Returns an iterator over fields.
+    fn iter<'a, 'h: 'a>(
+        &'a self,
+        header: &'h Header,
+    ) -> Box<dyn Iterator<Item = io::Result<(&'a str, Option<Value<'a>>)>> + 'a>;
+}