Vendor things

third-party/vendor/bindgen/ir/derive.rs

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+//! Traits for determining whether we can derive traits for a thing or not.
+//!
+//! These traits tend to come in pairs:
+//!
+//! 1. A "trivial" version, whose implementations aren't allowed to recursively
+//! look at other types or the results of fix point analyses.
+//!
+//! 2. A "normal" version, whose implementations simply query the results of a
+//! fix point analysis.
+//!
+//! The former is used by the analyses when creating the results queried by the
+//! second.
+
+use super::context::BindgenContext;
+
+use std::cmp;
+use std::ops;
+
+/// A trait that encapsulates the logic for whether or not we can derive `Debug`
+/// for a given thing.
+pub trait CanDeriveDebug {
+    /// Return `true` if `Debug` can be derived for this thing, `false`
+    /// otherwise.
+    fn can_derive_debug(&self, ctx: &BindgenContext) -> bool;
+}
+
+/// A trait that encapsulates the logic for whether or not we can derive `Copy`
+/// for a given thing.
+pub trait CanDeriveCopy {
+    /// Return `true` if `Copy` can be derived for this thing, `false`
+    /// otherwise.
+    fn can_derive_copy(&self, ctx: &BindgenContext) -> bool;
+}
+
+/// A trait that encapsulates the logic for whether or not we can derive
+/// `Default` for a given thing.
+pub trait CanDeriveDefault {
+    /// Return `true` if `Default` can be derived for this thing, `false`
+    /// otherwise.
+    fn can_derive_default(&self, ctx: &BindgenContext) -> bool;
+}
+
+/// A trait that encapsulates the logic for whether or not we can derive `Hash`
+/// for a given thing.
+pub trait CanDeriveHash {
+    /// Return `true` if `Hash` can be derived for this thing, `false`
+    /// otherwise.
+    fn can_derive_hash(&self, ctx: &BindgenContext) -> bool;
+}
+
+/// A trait that encapsulates the logic for whether or not we can derive
+/// `PartialEq` for a given thing.
+pub trait CanDerivePartialEq {
+    /// Return `true` if `PartialEq` can be derived for this thing, `false`
+    /// otherwise.
+    fn can_derive_partialeq(&self, ctx: &BindgenContext) -> bool;
+}
+
+/// A trait that encapsulates the logic for whether or not we can derive
+/// `PartialOrd` for a given thing.
+pub trait CanDerivePartialOrd {
+    /// Return `true` if `PartialOrd` can be derived for this thing, `false`
+    /// otherwise.
+    fn can_derive_partialord(&self, ctx: &BindgenContext) -> bool;
+}
+
+/// A trait that encapsulates the logic for whether or not we can derive `Eq`
+/// for a given thing.
+pub trait CanDeriveEq {
+    /// Return `true` if `Eq` can be derived for this thing, `false` otherwise.
+    fn can_derive_eq(&self, ctx: &BindgenContext) -> bool;
+}
+
+/// A trait that encapsulates the logic for whether or not we can derive `Ord`
+/// for a given thing.
+pub trait CanDeriveOrd {
+    /// Return `true` if `Ord` can be derived for this thing, `false` otherwise.
+    fn can_derive_ord(&self, ctx: &BindgenContext) -> bool;
+}
+
+/// Whether it is possible or not to automatically derive trait for an item.
+///
+/// ```ignore
+///         No
+///          ^
+///          |
+///      Manually
+///          ^
+///          |
+///         Yes
+/// ```
+///
+/// Initially we assume that we can derive trait for all types and then
+/// update our understanding as we learn more about each type.
+#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord)]
+pub enum CanDerive {
+    /// Yes, we can derive automatically.
+    Yes,
+
+    /// The only thing that stops us from automatically deriving is that
+    /// array with more than maximum number of elements is used.
+    ///
+    /// This means we probably can "manually" implement such trait.
+    Manually,
+
+    /// No, we cannot.
+    No,
+}
+
+impl Default for CanDerive {
+    fn default() -> CanDerive {
+        CanDerive::Yes
+    }
+}
+
+impl CanDerive {
+    /// Take the least upper bound of `self` and `rhs`.
+    pub fn join(self, rhs: Self) -> Self {
+        cmp::max(self, rhs)
+    }
+}
+
+impl ops::BitOr for CanDerive {
+    type Output = Self;
+
+    fn bitor(self, rhs: Self) -> Self::Output {
+        self.join(rhs)
+    }
+}
+
+impl ops::BitOrAssign for CanDerive {
+    fn bitor_assign(&mut self, rhs: Self) {
+        *self = self.join(rhs)
+    }
+}