feat: add HAS_INF/HAS_NAN/HAS_FINITE_ONLY format query constants

src/bits.rs

@@ -175,7 +175,7 @@ pub const fn is_nan_bits<F: Format>(bits: u8) -> bool {
 }
 
 pub fn is_infinity_bits<F: Format>(bits: u8) -> bool {
-    F::OVERFLOW == Overflow::Infinity
+    F::HAS_INF
         && exponent_field::<F>(bits) == F::MAX_EXPONENT_FIELD
         && mantissa_field::<F>(bits) == 0
 }

src/format.rs

@@ -60,4 +60,102 @@ pub trait Format: Copy + 'static {
         reason = "format exponent fields fit in eight storage bits"
     )]
     const MAX_EXPONENT_FIELD: u8 = ((1u16 << Self::EXPONENT_BITS) - 1) as u8;
+
+    /// Returns `true` if this format can represent infinity.
+    ///
+    /// A format has infinity when its overflow behavior is
+    /// [`Overflow::Infinity`]. Formats with `Overflow::Nan` or
+    /// `Overflow::Saturate` do not represent infinity.
+    const HAS_INF: bool = matches!(Self::OVERFLOW, Overflow::Infinity);
+
+    /// Returns `true` if this format can represent NaN values.
+    ///
+    /// A format has NaN if its NaN encoding is anything except
+    /// [`NanEncoding::None`].
+    const HAS_NAN: bool = !matches!(Self::NAN, NanEncoding::None);
+
+    /// Returns `true` if this format saturates on overflow.
+    const HAS_FINITE_ONLY: bool = matches!(Self::OVERFLOW, Overflow::Saturate);
+}
+
+#[cfg(test)]
+#[expect(
+    clippy::assertions_on_constants,
+    reason = "tests verify const trait associated constants"
+)]
+mod tests {
+    use super::*;
+    use crate::{
+        Float4E2M1FnFormat, Float6E2M3FnFormat, Float6E3M2FnFormat, Float8E3M4Format,
+        Float8E4M3B11FnuzFormat, Float8E4M3FnFormat, Float8E4M3FnuzFormat, Float8E4M3Format,
+        Float8E5M2FnuzFormat, Float8E5M2Format, Float8E8M0FnuFormat,
+    };
+
+    // Single NaN with Unsigned zero (E4M3B11FNuz) — has NaN, no Inf, no saturate
+    #[test]
+    fn single_nan_unsigned_zero_b11_format() {
+        assert!(!<Float8E4M3B11FnuzFormat as Format>::HAS_INF);
+        assert!(<Float8E4M3B11FnuzFormat as Format>::HAS_NAN);
+        assert!(!<Float8E4M3B11FnuzFormat as Format>::HAS_FINITE_ONLY);
+    }
+
+    // IEEE-like formats (E5M2, E4M3, E3M4) — has Inf, has NaN, no saturate
+    #[test]
+    fn ieee_formats_has_inf_nan() {
+        assert!(<Float8E5M2Format as Format>::HAS_INF);
+        assert!(<Float8E5M2Format as Format>::HAS_NAN);
+        assert!(!<Float8E5M2Format as Format>::HAS_FINITE_ONLY);
+
+        assert!(<Float8E4M3Format as Format>::HAS_INF);
+        assert!(<Float8E4M3Format as Format>::HAS_NAN);
+        assert!(!<Float8E4M3Format as Format>::HAS_FINITE_ONLY);
+
+        assert!(<Float8E3M4Format as Format>::HAS_INF);
+        assert!(<Float8E3M4Format as Format>::HAS_NAN);
+        assert!(!<Float8E3M4Format as Format>::HAS_FINITE_ONLY);
+    }
+
+    // Outer NaN formats (E4M3FN) — has NaN, no Inf, no saturate
+    #[test]
+    fn outer_nan_formats_has_nan() {
+        assert!(!<Float8E4M3FnFormat as Format>::HAS_INF);
+        assert!(<Float8E4M3FnFormat as Format>::HAS_NAN);
+        assert!(!<Float8E4M3FnFormat as Format>::HAS_FINITE_ONLY);
+    }
+
+    // Single NaN, Unsigned zero formats (E4M3FNuz, E5M2FNuz) — has NaN, no Inf
+    #[test]
+    fn single_nan_unsigned_zero_formats() {
+        assert!(!<Float8E4M3FnuzFormat as Format>::HAS_INF);
+        assert!(<Float8E4M3FnuzFormat as Format>::HAS_NAN);
+        assert!(!<Float8E4M3FnuzFormat as Format>::HAS_FINITE_ONLY);
+
+        assert!(!<Float8E5M2FnuzFormat as Format>::HAS_INF);
+        assert!(<Float8E5M2FnuzFormat as Format>::HAS_NAN);
+        assert!(!<Float8E5M2FnuzFormat as Format>::HAS_FINITE_ONLY);
+    }
+
+    // Single NaN, unsigned sign format (E8M0FNU) — has NaN, no Inf
+    #[test]
+    fn unsigned_e8m0_format() {
+        assert!(!<Float8E8M0FnuFormat as Format>::HAS_INF);
+        assert!(<Float8E8M0FnuFormat as Format>::HAS_NAN);
+        assert!(!<Float8E8M0FnuFormat as Format>::HAS_FINITE_ONLY);
+    }
+
+    // Saturate formats (F4, F6) — no Inf, no NaN, finite only
+    #[test]
+    fn saturate_formats_finite_only() {
+        assert!(!<Float4E2M1FnFormat as Format>::HAS_INF);
+        assert!(!<Float4E2M1FnFormat as Format>::HAS_NAN);
+        assert!(<Float4E2M1FnFormat as Format>::HAS_FINITE_ONLY);
+
+        assert!(!<Float6E2M3FnFormat as Format>::HAS_INF);
+        assert!(!<Float6E2M3FnFormat as Format>::HAS_NAN);
+        assert!(<Float6E2M3FnFormat as Format>::HAS_FINITE_ONLY);
+
+        assert!(!<Float6E3M2FnFormat as Format>::HAS_INF);
+        assert!(!<Float6E3M2FnFormat as Format>::HAS_NAN);
+        assert!(<Float6E3M2FnFormat as Format>::HAS_FINITE_ONLY);
+    }
 }

src/formats.rs

@@ -274,6 +274,21 @@ macro_rules! define_format {
                 self.0.to_ne_bytes()
             }
 
+            /// Returns `true` if this format can represent infinity.
+            pub const fn has_inf() -> bool {
+                <$format as crate::format::Format>::HAS_INF
+            }
+
+            /// Returns `true` if this format can represent NaN values.
+            pub const fn has_nan() -> bool {
+                <$format as crate::format::Format>::HAS_NAN
+            }
+
+            /// Returns `true` if this format saturates on overflow (finite-only).
+            pub const fn is_finite_only() -> bool {
+                <$format as crate::format::Format>::HAS_FINITE_ONLY
+            }
+
             /// Converts an `f32` to this format.
             ///
             /// The result is rounded to the nearest representable value. Values outside the

src/micro.rs

@@ -186,7 +186,7 @@ impl<F: Format> MicroFloat<F> {
             }
             return self;
         }
-        if F::NAN == NanEncoding::None
+        if !F::HAS_NAN
             && self.is_sign_negative()
             && self.classify() != FpCategory::Zero
             && !is_integer(n.to_f32())
@@ -197,10 +197,7 @@ impl<F: Format> MicroFloat<F> {
     }
 
     pub fn sqrt(self) -> Self {
-        if F::NAN == NanEncoding::None
-            && self.is_sign_negative()
-            && self.classify() != FpCategory::Zero
-        {
+        if !F::HAS_NAN && self.is_sign_negative() && self.classify() != FpCategory::Zero {
             return Self::ZERO;
         }
         unary_result(self, libm::sqrtf(self.to_f32()))
@@ -219,27 +216,21 @@ impl<F: Format> MicroFloat<F> {
     }
 
     pub fn ln(self) -> Self {
-        if F::NAN == NanEncoding::None
-            && self.is_sign_negative()
-            && self.classify() != FpCategory::Zero
-        {
+        if !F::HAS_NAN && self.is_sign_negative() && self.classify() != FpCategory::Zero {
             return Self::ZERO;
         }
         unary_result(self, libm::logf(self.to_f32()))
     }
 
     pub fn ln_1p(self) -> Self {
-        if F::NAN == NanEncoding::None && self.to_f32() < -1.0 {
+        if !F::HAS_NAN && self.to_f32() < -1.0 {
             return Self::ZERO;
         }
         unary_result(self, libm::log1pf(self.to_f32()))
     }
 
     pub fn log2(self) -> Self {
-        if F::NAN == NanEncoding::None
-            && self.is_sign_negative()
-            && self.classify() != FpCategory::Zero
-        {
+        if !F::HAS_NAN && self.is_sign_negative() && self.classify() != FpCategory::Zero {
             return Self::ZERO;
         }
         unary_result(self, libm::log2f(self.to_f32()))

tests/format_edges.rs

@@ -1,4 +1,7 @@
-use microfloat::{f4e2m1fn, f8e4m3, f8e4m3b11fnuz, f8e4m3fn, f8e4m3fnuz, f8e8m0fnu};
+use microfloat::{
+    f4e2m1fn, f6e2m3fn, f6e3m2fn, f8e3m4, f8e4m3, f8e4m3b11fnuz, f8e4m3fn, f8e4m3fnuz, f8e5m2,
+    f8e5m2fnuz, f8e8m0fnu,
+};
 
 #[test]
 fn special_constants_cover_format_modes() {
@@ -38,3 +41,50 @@ fn clamp_panics_when_min_is_nan() {
 fn clamp_panics_when_max_is_nan() {
     let _ = std::panic::catch_unwind(|| f8e4m3::ZERO.clamp(f8e4m3::ONE, f8e4m3::NAN));
 }
+
+#[test]
+fn format_query_helpers() {
+    assert!(f8e3m4::has_inf());
+    assert!(f8e3m4::has_nan());
+    assert!(!f8e3m4::is_finite_only());
+
+    assert!(f8e4m3::has_inf());
+    assert!(f8e4m3::has_nan());
+    assert!(!f8e4m3::is_finite_only());
+
+    assert!(f8e5m2::has_inf());
+    assert!(f8e5m2::has_nan());
+    assert!(!f8e5m2::is_finite_only());
+
+    assert!(!f8e4m3fn::has_inf());
+    assert!(f8e4m3fn::has_nan());
+    assert!(!f8e4m3fn::is_finite_only());
+
+    assert!(!f8e4m3fnuz::has_inf());
+    assert!(f8e4m3fnuz::has_nan());
+    assert!(!f8e4m3fnuz::is_finite_only());
+
+    assert!(!f8e5m2fnuz::has_inf());
+    assert!(f8e5m2fnuz::has_nan());
+    assert!(!f8e5m2fnuz::is_finite_only());
+
+    assert!(!f8e4m3b11fnuz::has_inf());
+    assert!(f8e4m3b11fnuz::has_nan());
+    assert!(!f8e4m3b11fnuz::is_finite_only());
+
+    assert!(!f8e8m0fnu::has_inf());
+    assert!(f8e8m0fnu::has_nan());
+    assert!(!f8e8m0fnu::is_finite_only());
+
+    assert!(!f4e2m1fn::has_inf());
+    assert!(!f4e2m1fn::has_nan());
+    assert!(f4e2m1fn::is_finite_only());
+
+    assert!(!f6e2m3fn::has_inf());
+    assert!(!f6e2m3fn::has_nan());
+    assert!(f6e2m3fn::is_finite_only());
+
+    assert!(!f6e3m2fn::has_inf());
+    assert!(!f6e3m2fn::has_nan());
+    assert!(f6e3m2fn::is_finite_only());
+}