Make predicates inconstructible.

Author: nekitdev

README.md

@@ -48,7 +48,7 @@ use refinement_types::{Refinement, int::u8, length, logic::And, str};
 pub type Name<'n> = Refinement<&'n str, And<str::Ascii, length::Closed<1, 32>>>;
 
 /// Represents device charge, in percentage.
-pub type Charge = Refinement<u8, u8::Closed<1, 100>>;
+pub type Charge = Refinement<u8, u8::LessOrEqual<100>>;
 
 /// Represents devices.
 #[derive(Debug)]
@@ -83,8 +83,8 @@ impl<'d> Device<'d> {
 ```rust
 // main.rs
 
-use anyhow::Result;
 use device::{Charge, Device, Name};
+use miette::Result;
 
 fn main() -> Result<()> {
     let charge = Charge::refine(13)?;

src/char/ascii.rs

@@ -1,6 +1,6 @@
 //! ASCII character predicates.
 
-use core::fmt;
+use core::{fmt, marker::PhantomData};
 
 #[cfg(feature = "diagnostics")]
 use miette::Diagnostic;
@@ -39,8 +39,9 @@ impl DigitError {
 }
 
 /// Checks whether the given character is a digit in the specified base `B`.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
-pub struct Digit<const B: Base = 10>;
+pub struct Digit<const B: Base = 10> {
+    private: PhantomData<()>,
+}
 
 /// Checks whether the given character is an octal digit.
 pub type OctDigit = Digit<8>;

src/char/macros.rs

@@ -1,5 +1,5 @@
 pub(crate) mod import {
-    pub use core::fmt;
+    pub use core::{fmt, marker::PhantomData};
 
     pub use paste::paste;
     pub use thiserror::Error;
@@ -37,9 +37,10 @@ macro_rules! predicate {
                 }
             }
 
-            #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
             #[doc = $doc]
-            pub struct $name;
+            pub struct $name {
+                private: $crate::char::macros::import::PhantomData<()>,
+            }
 
             impl $crate::core::Predicate<char> for $name {
                 type Error = [< $name Error >];

src/core.rs

@@ -86,12 +86,12 @@ pub trait Predicate<T: ?Sized> {
 }
 
 /// Represents expectations of predicates.
-pub struct Expected<T: ?Sized, P: Predicate<T> + ?Sized> {
+pub struct Expected<T: ?Sized, P: ?Sized> {
     value: PhantomData<T>,
     predicate: PhantomData<P>,
 }
 
-impl<T: ?Sized, P: Predicate<T> + ?Sized> Expected<T, P> {
+impl<T: ?Sized, P: ?Sized> Expected<T, P> {
     const fn new() -> Self {
         Self {
             value: PhantomData,
@@ -107,12 +107,12 @@ impl<T: ?Sized, P: Predicate<T> + ?Sized> fmt::Display for Expected<T, P> {
 }
 
 /// Represents expectation codes of predicates.
-pub struct ExpectedCode<T: ?Sized, P: Predicate<T> + ?Sized> {
+pub struct ExpectedCode<T: ?Sized, P: ?Sized> {
     value: PhantomData<T>,
     predicate: PhantomData<P>,
 }
 
-impl<T: ?Sized, P: Predicate<T> + ?Sized> ExpectedCode<T, P> {
+impl<T: ?Sized, P: ?Sized> ExpectedCode<T, P> {
     const fn new() -> Self {
         Self {
             value: PhantomData,
@@ -413,6 +413,16 @@ impl<T, P: Predicate<T> + ?Sized, H: TypeStr + ?Sized> Refinement<T, P, H> {
         Self::refine(function(self.take()))
     }
 
+    /// Maps thte value of the refinement without checking the new value.
+    ///
+    /// # Safety
+    ///
+    /// The caller must ensure that the new value satisfies the predicate.
+    pub unsafe fn map_unchecked<F: FnOnce(T) -> T>(self, function: F) -> Self {
+        // SAFETY: the caller must ensure that the new value satisfies the predicate
+        unsafe { Self::unchecked(function(self.take())) }
+    }
+
     /// Replaces the value of the refinement.
     ///
     /// # Errors
@@ -422,6 +432,16 @@ impl<T, P: Predicate<T> + ?Sized, H: TypeStr + ?Sized> Refinement<T, P, H> {
         Self::refine(value)
     }
 
+    /// Replaces the value of the refinement without checking the new value.
+    ///
+    /// # Safety
+    ///
+    /// The caller must ensure that the new value satisfies the predicate.
+    pub unsafe fn replace_unchecked(self, value: T) -> Self {
+        // SAFETY: the caller must ensure that the new value satisfies the predicate
+        unsafe { Self::unchecked(value) }
+    }
+
     #[cfg(feature = "unsafe-assert")]
     fn assert_refined(&self) {
         unsafe { assert_unchecked(Self::is_fine(&self.value)) }
@@ -436,7 +456,7 @@ impl<T, P: Predicate<T> + ?Sized, H: TypeStr + ?Sized> Refinement<T, P, H> {
     }
 
     /// Returns a reference to the value of the refinement.
-    #[allow(clippy::missing_const_for_fn)]
+    #[allow(clippy::missing_const_for_fn)] // conditionally const
     pub fn get(&self) -> &T {
         #[cfg(feature = "unsafe-assert")]
         self.assert_refined();

src/empty.rs

@@ -1,6 +1,7 @@
 //! Predicates based on emptiness.
 
 use core::fmt;
+use core::marker::PhantomData;
 
 use thiserror::Error;
 
@@ -31,8 +32,9 @@ pub const VALUE: StaticStr = "empty value";
 pub const EMPTY: StaticStr = "empty";
 
 /// Checks whether the value is empty.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
-pub struct Empty;
+pub struct Empty {
+    private: PhantomData<()>,
+}
 
 impl<T: HasEmpty + ?Sized> Predicate<T> for Empty {
     type Error = EmptyError;

src/int/macros.rs

@@ -1,5 +1,5 @@
 pub(crate) mod import {
-    pub use core::fmt;
+    pub use core::{fmt, marker::PhantomData};
 
     pub use paste::paste;
     pub use thiserror::Error;
@@ -129,8 +129,9 @@ macro_rules! compare {
                 $crate::int::macros::human!($operation),
                 " `N`."
             )]
-            #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
-            pub struct $name<const N: $int>;
+            pub struct $name<const N: $int> {
+                private: $crate::int::macros::import::PhantomData<()>,
+            }
 
             impl<const N: $int> $crate::core::Predicate<$int> for $name<N> {
                 type Error = [< $name Error >];
@@ -313,7 +314,7 @@ macro_rules! modulo {
             feature = "diagnostics",
             derive($crate::int::macros::import::Diagnostic),
             diagnostic(
-                code(int::$int::Modulo),
+                code(int::$int::modulo),
                 help("make sure the value divided by {divisor} and has modulo {modulo}")
             )
         )]
@@ -334,8 +335,9 @@ macro_rules! modulo {
         #[doc = concat!(
             "Checks whether ", $crate::int::macros::reference!($int), " divided by `D` has modulo `M`."
         )]
-        #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
-        pub struct Modulo<const D: $int, const M: $int>;
+        pub struct Modulo<const D: $int, const M: $int> {
+            private: $crate::int::macros::import::PhantomData<()>,
+        }
 
         impl<const D: $int, const M: $int> $crate::core::Predicate<$int> for Modulo<D, M> {
             type Error = ModuloError;

src/length.rs

@@ -1,6 +1,6 @@
 //! Predicates based on length.
 
-use core::fmt;
+use core::{fmt, marker::PhantomData};
 
 #[cfg(feature = "diagnostics")]
 use miette::Diagnostic;
@@ -40,8 +40,9 @@ impl LessError {
 }
 
 /// Checks whether the given value has length less than `N`.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
-pub struct Less<const N: usize>;
+pub struct Less<const N: usize> {
+    private: PhantomData<()>,
+}
 
 impl<const N: usize, T: HasLength + ?Sized> Predicate<T> for Less<N> {
     type Error = LessError;
@@ -88,8 +89,9 @@ impl LessOrEqualError {
 }
 
 /// Checks whether the given value has length less than or equal to `N`.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
-pub struct LessOrEqual<const N: usize>;
+pub struct LessOrEqual<const N: usize> {
+    private: PhantomData<()>,
+}
 
 impl<const N: usize, T: HasLength + ?Sized> Predicate<T> for LessOrEqual<N> {
     type Error = LessOrEqualError;
@@ -133,8 +135,9 @@ impl GreaterError {
 }
 
 /// Checks whether the given value has length greater than `N`.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
-pub struct Greater<const N: usize>;
+pub struct Greater<const N: usize> {
+    private: PhantomData<()>,
+}
 
 impl<const N: usize, T: HasLength + ?Sized> Predicate<T> for Greater<N> {
     type Error = GreaterError;
@@ -181,8 +184,9 @@ impl GreaterOrEqualError {
 }
 
 /// Checks whether the given value has length greater than or equal to `N`.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
-pub struct GreaterOrEqual<const N: usize>;
+pub struct GreaterOrEqual<const N: usize> {
+    private: PhantomData<()>,
+}
 
 impl<const N: usize, T: HasLength + ?Sized> Predicate<T> for GreaterOrEqual<N> {
     type Error = GreaterOrEqualError;
@@ -226,8 +230,9 @@ impl EqualError {
 }
 
 /// Checks whether the given value has length equal to `N`.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
-pub struct Equal<const N: usize>;
+pub struct Equal<const N: usize> {
+    private: PhantomData<()>,
+}
 
 impl<const N: usize, T: HasLength + ?Sized> Predicate<T> for Equal<N> {
     type Error = EqualError;
@@ -271,8 +276,9 @@ impl NotEqualError {
 }
 
 /// Checks whether the given value has length not equal to `N`.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
-pub struct NotEqual<const N: usize>;
+pub struct NotEqual<const N: usize> {
+    private: PhantomData<()>,
+}
 
 impl<const N: usize, T: HasLength + ?Sized> Predicate<T> for NotEqual<N> {
     type Error = NotEqualError;
@@ -335,8 +341,9 @@ impl ModuloError {
 }
 
 /// Checks whether the given value length divided by `D` has modulo `M`.
-#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
-pub struct Modulo<const D: usize, const M: usize>;
+pub struct Modulo<const D: usize, const M: usize> {
+    private: PhantomData<()>,
+}
 
 impl<const D: usize, const M: usize, T: HasLength + ?Sized> Predicate<T> for Modulo<D, M> {
     type Error = ModuloError;

src/logic.rs

@@ -13,8 +13,9 @@ use crate::{
 };
 
 /// Represents predicates that are always satisfied.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
-pub struct True;
+pub struct True {
+    private: PhantomData<()>,
+}
 
 /// Represents errors that are never encountered.
 ///
@@ -51,8 +52,9 @@ impl<T: ?Sized> Predicate<T> for True {
 }
 
 /// Represents predicates that are never satisfied.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
-pub struct False;
+pub struct False {
+    private: PhantomData<()>,
+}
 
 /// Represents errors that are always encountered.
 #[derive(Debug, Error)]
@@ -132,7 +134,6 @@ impl<E: Diagnostic + 'static, F: Diagnostic + 'static> Diagnostic for EitherErro
 }
 
 /// Represents predicates that are satisfied when both `P` and `Q` are satisfied.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
 pub struct And<P: ?Sized, Q: ?Sized> {
     left: PhantomData<P>,
     right: PhantomData<Q>,
@@ -143,8 +144,8 @@ impl<T: ?Sized, P: Predicate<T> + ?Sized, Q: Predicate<T> + ?Sized> Predicate<T>
 
     fn check(value: &T) -> Result<(), Self::Error> {
         P::check(value)
-            .map_err(EitherError::Left)
-            .and_then(|()| Q::check(value).map_err(EitherError::Right))
+            .map_err(Self::Error::Left)
+            .and_then(|()| Q::check(value).map_err(Self::Error::Right))
     }
 
     fn expect(formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
@@ -202,7 +203,6 @@ impl<E: Diagnostic, F: Diagnostic> Diagnostic for BothError<E, F> {
 }
 
 /// Represents predicates that are satisfied when either `P` or `Q` (or both) are satisfied.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
 pub struct Or<P: ?Sized, Q: ?Sized> {
     left: PhantomData<P>,
     right: PhantomData<Q>,
@@ -248,7 +248,6 @@ impl NotError {
 }
 
 /// Represents predicates that are satisfied when `P` is not satisfied.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
 pub struct Not<P: ?Sized> {
     predicate: PhantomData<P>,
 }
@@ -318,7 +317,6 @@ impl<E: Diagnostic + 'static, F: Diagnostic + 'static> Diagnostic for NeitherOrB
 }
 
 /// Represents predicates that are satisfied when either `P` or `Q` (but *not* both) are satisfied.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
 pub struct Xor<P: ?Sized, Q: ?Sized> {
     left: PhantomData<P>,
     right: PhantomData<Q>,