1 files changed, 81 insertions, 0 deletions
diff --git a/src/eval/int.rs b/src/eval/int.rs
new file mode 100644
index 00000000..4e081617
--- /dev/null
+++ b/src/eval/int.rs
@@ -0,0 +1,81 @@
+use std::num::{NonZeroI64, NonZeroIsize, NonZeroU64, NonZeroUsize};
+
+use super::{cast, Value};
+
+macro_rules! signed_int {
+    ($($ty:ty)*) => {
+        $(cast! {
+            $ty,
+            self => Value::Int(self as i64),
+            v: i64 => v.try_into().map_err(|_| "number too large")?,
+        })*
+    }
+}
+
+macro_rules! unsigned_int {
+    ($($ty:ty)*) => {
+        $(cast! {
+            $ty,
+            self => Value::Int(self as i64),
+            v: i64 => v.try_into().map_err(|_| {
+                if v < 0 {
+                    "number must be at least zero"
+                } else {
+                    "number too large"
+                }
+            })?,
+        })*
+    }
+}
+
+macro_rules! signed_nonzero {
+    ($($ty:ty)*) => {
+        $(cast! {
+            $ty,
+            self => Value::Int(self.get() as i64),
+            v: i64 => v
+                .try_into()
+                .ok()
+                .and_then($ty::new)
+                .ok_or_else(|| if v == 0 {
+                    "number must not be zero"
+                } else {
+                    "number too large"
+                })?,
+        })*
+    }
+}
+
+macro_rules! unsigned_nonzero {
+    ($($ty:ty)*) => {
+        $(cast! {
+            $ty,
+            self => Value::Int(self.get() as i64),
+            v: i64 => v
+                .try_into()
+                .ok()
+                .and_then($ty::new)
+                .ok_or_else(|| if v <= 0 {
+                    "number must be positive"
+                } else {
+                    "number too large"
+                })?,
+        })*
+    }
+}
+
+signed_int! {
+    i8 i16 i32 isize
+}
+
+unsigned_int! {
+    u8 u16 u32 u64 usize
+}
+
+signed_nonzero! {
+    NonZeroI64 NonZeroIsize
+}
+
+unsigned_nonzero! {
+    NonZeroU64  NonZeroUsize
+}