1 files changed, 94 insertions, 0 deletions
diff --git a/src/str.rs b/src/str.rs
new file mode 100644
index 0000000..1825e06
--- /dev/null
+++ b/src/str.rs
@@ -0,0 +1,94 @@
+// Copyright © 2022 Kim Altintop <kim@eagain.io>
+// SPDX-License-Identifier: GPL-2.0-only WITH openvpn-openssl-exception
+
+use core::fmt;
+use std::{
+    ops::Deref,
+    str::FromStr,
+};
+
+use anyhow::ensure;
+
+// A variable-length string type with a maximum length `N`.
+#[derive(Clone, Debug, Eq, Ord, PartialEq, PartialOrd, serde::Serialize)]
+pub struct Varchar<T, const N: usize>(T);
+
+impl<T, const N: usize> Varchar<T, N>
+where
+    T: AsRef<str>,
+{
+    pub fn len(&self) -> usize {
+        self.0.as_ref().len()
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.0.as_ref().is_empty()
+    }
+
+    fn try_from_t(t: T) -> crate::Result<Self> {
+        let len = t.as_ref().len();
+        ensure!(len <= N, "string length exceeds {N}: {len}");
+        Ok(Self(t))
+    }
+}
+
+impl<const N: usize> Varchar<String, N> {
+    pub const fn new() -> Self {
+        Self(String::new())
+    }
+}
+
+impl<const N: usize> TryFrom<String> for Varchar<String, N> {
+    type Error = crate::Error;
+
+    fn try_from(s: String) -> Result<Self, Self::Error> {
+        Self::try_from_t(s)
+    }
+}
+
+impl<const N: usize> FromStr for Varchar<String, N> {
+    type Err = crate::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        Self::try_from(s.to_owned())
+    }
+}
+
+impl<'a, const N: usize> TryFrom<&'a str> for Varchar<&'a str, N> {
+    type Error = crate::Error;
+
+    fn try_from(s: &'a str) -> Result<Self, Self::Error> {
+        Self::try_from_t(s)
+    }
+}
+
+impl<T, const N: usize> Deref for Varchar<T, N> {
+    type Target = T;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl<T, const N: usize> fmt::Display for Varchar<T, N>
+where
+    T: AsRef<str>,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str(self.0.as_ref())
+    }
+}
+
+impl<'de, T, const N: usize> serde::Deserialize<'de> for Varchar<T, N>
+where
+    T: serde::Deserialize<'de> + TryInto<Self>,
+    <T as TryInto<Self>>::Error: fmt::Display,
+{
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        let t = T::deserialize(deserializer)?;
+        t.try_into().map_err(serde::de::Error::custom)
+    }
+}