Add trait IntoAsciiString to replace OwnedAsciiCast

Trait and method names are the only difference.

Author: tormol

src/ascii_string.rs

@@ -551,6 +551,44 @@ impl<T> IndexMut<T> for AsciiString where AsciiStr: IndexMut<T> {
     }
 }
 
+
+/// Trait for converting vectors into `AsciiString`.
+pub trait IntoAsciiString<T: ?Sized+AsciiExt<Owned=Self>> : Sized+Borrow<T> {
+    /// Convert to `AsciiString` without checking that every byte is less than 128.
+    unsafe fn into_ascii_unchecked(self) -> AsciiString;
+    /// Convert to `AsciiString`.
+    fn into_ascii(self) -> Result<AsciiString,Self> {
+        if self.borrow().is_ascii() {
+            Ok(unsafe { self.into_ascii_unchecked() })
+        } else {
+            Err(self)
+        }
+    }
+}
+
+#[cfg(feature = "unstable")]
+impl IntoAsciiString<AsciiStr> for AsciiString {
+    fn into_ascii(self) -> Result<AsciiString,AsciiString> {
+        Ok(self)
+    }
+    unsafe fn into_ascii_unchecked(self) -> AsciiString {
+        self
+    }
+}
+
+impl IntoAsciiString<[u8]> for Vec<u8> {
+    unsafe fn into_ascii_unchecked(self) -> AsciiString {
+        AsciiString::from_bytes_unchecked(self)
+    }
+}
+
+impl IntoAsciiString<str> for String {
+    unsafe fn into_ascii_unchecked(self) -> AsciiString {
+        self.into_bytes().into_ascii_unchecked()
+    }
+}
+
+
 #[cfg(test)]
 mod tests {
     use std::str::FromStr;

src/lib.rs

@@ -20,7 +20,7 @@ use std::borrow::Borrow;
 use std::ascii::AsciiExt;
 
 pub use ascii::{Ascii, IntoAscii, IntoAsciiError};
-pub use ascii_string::AsciiString;
+pub use ascii_string::{AsciiString, IntoAsciiString};
 pub use ascii_str::AsciiStr;
 
 /// Trait for converting into an ascii type.