api for variant

Author: burrbull

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+### Added
+
+- Option-like API for `generic::Variant`
+
 ## [v0.16.1] - 2019-08-17
 
 ### Fixed

src/generate/generic.rs

@@ -227,3 +227,63 @@ pub enum Variant<U, T> {
     ///Raw bits
     Res(U),
 }
+
+use Variant::*;
+impl<U, T> Variant<U, T> {
+    /// Check if the variant is expected
+    pub fn is_value(&self) -> bool {
+        match self {
+            Val(_) => true,
+            Res(_) => false,
+        }
+    }
+    /// Check if the variant is not expected
+    pub fn is_reserved(&self) -> bool {
+        match self {
+            Val(_) => false,
+            Res(_) => true,
+        }
+    }
+
+    /// Returns the contained value or a default
+    #[inline]
+    pub fn unwrap_or(self, def: T) -> T {
+        match self {
+            Val(v) => v,
+            Res(_) => def,
+        }
+    }
+
+    /// Returns the contained value or computes it from a closure
+    #[inline]
+    pub fn unwrap_or_else<F: FnOnce(U) -> T>(self, f: F) -> T {
+        match self {
+            Val(v) => v,
+            Res(u) => f(u),
+        }
+    }
+}
+
+impl<U, T> Variant<U, T> where U: core::fmt::Debug {
+    /// Moves the value `v` out of the `Variant` if it is `Val(v)`.
+    ///
+    /// Panics if the self value equals `Res`
+    #[inline]
+    pub fn unwrap(self) -> T {
+        match self {
+            Val(v) => v,
+            Res(u) => panic!("Unexpected variant: {:?}", u),
+        }
+    }
+
+    /// Unwraps a result, yielding the content of an `Val`.
+    ///
+    /// Panics if the value is an `Res`, with a panic message including the
+    /// passed message, and the content of the `Res`.
+    pub fn expect(self, msg: &str) -> T {
+        match self {
+            Val(v) => v,
+            Res(u) => panic!("{}: {:?}", msg, u),
+        }
+    }
+}