1 files changed, 99 insertions, 0 deletions
diff --git a/src/asn1_types/null.rs b/src/asn1_types/null.rs
new file mode 100644
index 0000000..ba9f0f5
--- /dev/null
+++ b/src/asn1_types/null.rs
@@ -0,0 +1,99 @@
+use crate::*;
+use core::convert::TryFrom;
+
+/// ASN.1 `NULL` type
+#[derive(Debug, PartialEq, Eq)]
+pub struct Null {}
+
+impl Null {
+    pub const fn new() -> Self {
+        Null {}
+    }
+}
+
+impl<'a> TryFrom<Any<'a>> for Null {
+    type Error = Error;
+
+    fn try_from(any: Any<'a>) -> Result<Null> {
+        TryFrom::try_from(&any)
+    }
+}
+
+impl<'a, 'b> TryFrom<&'b Any<'a>> for Null {
+    type Error = Error;
+
+    fn try_from(any: &'b Any<'a>) -> Result<Null> {
+        any.tag().assert_eq(Self::TAG)?;
+        if !any.header.length.is_null() {
+            return Err(Error::InvalidLength);
+        }
+        Ok(Null {})
+    }
+}
+
+impl CheckDerConstraints for Null {
+    fn check_constraints(_any: &Any) -> Result<()> {
+        Ok(())
+    }
+}
+
+impl DerAutoDerive for Null {}
+
+impl Tagged for Null {
+    const TAG: Tag = Tag::Null;
+}
+
+#[cfg(feature = "std")]
+impl ToDer for Null {
+    fn to_der_len(&self) -> Result<usize> {
+        Ok(2)
+    }
+
+    fn write_der_header(&self, writer: &mut dyn std::io::Write) -> SerializeResult<usize> {
+        writer.write(&[0x05, 0x00]).map_err(Into::into)
+    }
+
+    fn write_der_content(&self, _writer: &mut dyn std::io::Write) -> SerializeResult<usize> {
+        Ok(0)
+    }
+}
+
+impl<'a> TryFrom<Any<'a>> for () {
+    type Error = Error;
+
+    fn try_from(any: Any<'a>) -> Result<()> {
+        any.tag().assert_eq(Self::TAG)?;
+        any.header.assert_primitive()?;
+        if !any.header.length.is_null() {
+            return Err(Error::InvalidLength);
+        }
+        Ok(())
+    }
+}
+
+impl CheckDerConstraints for () {
+    fn check_constraints(_any: &Any) -> Result<()> {
+        Ok(())
+    }
+}
+
+impl DerAutoDerive for () {}
+
+impl Tagged for () {
+    const TAG: Tag = Tag::Null;
+}
+
+#[cfg(feature = "std")]
+impl ToDer for () {
+    fn to_der_len(&self) -> Result<usize> {
+        Ok(2)
+    }
+
+    fn write_der_header(&self, writer: &mut dyn std::io::Write) -> SerializeResult<usize> {
+        writer.write(&[0x05, 0x00]).map_err(Into::into)
+    }
+
+    fn write_der_content(&self, _writer: &mut dyn std::io::Write) -> SerializeResult<usize> {
+        Ok(0)
+    }
+}