dec2flt: Move internal traits to better locations

`Float` and `FloatExt` are already used by both parsing and printing, so
move them out of `dec2flt` to a new module in `num::imp`. `Int` `Cast`
have the potential to be used more places in the future, so move them
there as well. `Lemire` is the only remaining trait; since it is small,
move it into the `dec2flt` root.

The `fmt::LowerExp` bound is removed from `Float` here since the trait
is moving into a module without `#[cfg(not(no_fp_fmt_parse))]` and it
isn't implemented with that config (it's not easily possible to add
`cfg` attributes to a single supertrait, unfortunately). This isn't a
problem since it isn't actually being used.

library/core/src/num/imp/dec2flt/decimal.rs

@@ -1,9 +1,10 @@
 //! Representation of a float as the significant digits and exponent.
 
-use crate::num::imp::dec2flt;
-use dec2flt::float::Lemire;
+use dec2flt::Lemire;
 use dec2flt::fpu::set_precision;
 
+use crate::num::imp::dec2flt;
+
 const INT_POW10: [u64; 16] = [
     1,
     10,

library/core/src/num/imp/dec2flt/lemire.rs

@@ -1,10 +1,9 @@
 //! Implementation of the Eisel-Lemire algorithm.
 
 use dec2flt::common::BiasedFp;
-use dec2flt::float::Float;
 use dec2flt::table::{LARGEST_POWER_OF_FIVE, POWER_OF_FIVE_128, SMALLEST_POWER_OF_FIVE};
 
-use crate::num::imp::dec2flt;
+use crate::num::imp::{Float, dec2flt};
 
 /// Compute w * 10^q using an extended-precision float representation.
 ///

library/core/src/num/imp/dec2flt/mod.rs

@@ -88,24 +88,104 @@
 )]
 
 use common::BiasedFp;
-use float::{FloatExt, Lemire};
 use lemire::compute_float;
 use parse::{parse_inf_nan, parse_number};
 use slow::parse_long_mantissa;
 
+use crate::f64;
 use crate::num::ParseFloatError;
 use crate::num::float_parse::FloatErrorKind;
+use crate::num::imp::FloatExt;
 
 mod common;
 pub mod decimal;
 pub mod decimal_seq;
 mod fpu;
-mod slow;
-mod table;
-// float is used in flt2dec, and all are used in unit tests.
-pub mod float;
 pub mod lemire;
 pub mod parse;
+mod slow;
+mod table;
+
+/// Extension to `Float` that are necessary for parsing using the Lemire method.
+///
+/// See the parent module's doc comment for why this is necessary.
+///
+/// Not intended for use outside of the `dec2flt` module.
+#[doc(hidden)]
+pub trait Lemire: FloatExt {
+    /// Maximum exponent for a fast path case, or `⌊(SIG_BITS+1)/log2(5)⌋`
+    // assuming FLT_EVAL_METHOD = 0
+    const MAX_EXPONENT_FAST_PATH: i64 = {
+        let log2_5 = f64::consts::LOG2_10 - 1.0;
+        (Self::SIG_TOTAL_BITS as f64 / log2_5) as i64
+    };
+
+    /// Minimum exponent for a fast path case, or `-⌊(SIG_BITS+1)/log2(5)⌋`
+    const MIN_EXPONENT_FAST_PATH: i64 = -Self::MAX_EXPONENT_FAST_PATH;
+
+    /// Maximum exponent that can be represented for a disguised-fast path case.
+    /// This is `MAX_EXPONENT_FAST_PATH + ⌊(SIG_BITS+1)/log2(10)⌋`
+    const MAX_EXPONENT_DISGUISED_FAST_PATH: i64 =
+        Self::MAX_EXPONENT_FAST_PATH + (Self::SIG_TOTAL_BITS as f64 / f64::consts::LOG2_10) as i64;
+
+    /// Maximum mantissa for the fast-path (`1 << 53` for f64).
+    const MAX_MANTISSA_FAST_PATH: u64 = 1 << Self::SIG_TOTAL_BITS;
+
+    /// Gets a small power-of-ten for fast-path multiplication.
+    fn pow10_fast_path(exponent: usize) -> Self;
+
+    /// Converts integer into float through an as cast.
+    /// This is only called in the fast-path algorithm, and therefore
+    /// will not lose precision, since the value will always have
+    /// only if the value is <= Self::MAX_MANTISSA_FAST_PATH.
+    fn from_u64(v: u64) -> Self;
+}
+
+#[cfg(target_has_reliable_f16)]
+impl Lemire for f16 {
+    fn pow10_fast_path(exponent: usize) -> Self {
+        #[allow(clippy::use_self)]
+        const TABLE: [f16; 8] = [1e0, 1e1, 1e2, 1e3, 1e4, 0.0, 0.0, 0.];
+        TABLE[exponent & 7]
+    }
+
+    #[inline]
+    fn from_u64(v: u64) -> Self {
+        debug_assert!(v <= Self::MAX_MANTISSA_FAST_PATH);
+        v as _
+    }
+}
+
+impl Lemire for f32 {
+    fn pow10_fast_path(exponent: usize) -> Self {
+        #[allow(clippy::use_self)]
+        const TABLE: [f32; 16] =
+            [1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9, 1e10, 0., 0., 0., 0., 0.];
+        TABLE[exponent & 15]
+    }
+
+    #[inline]
+    fn from_u64(v: u64) -> Self {
+        debug_assert!(v <= Self::MAX_MANTISSA_FAST_PATH);
+        v as _
+    }
+}
+
+impl Lemire for f64 {
+    fn pow10_fast_path(exponent: usize) -> Self {
+        const TABLE: [f64; 32] = [
+            1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9, 1e10, 1e11, 1e12, 1e13, 1e14, 1e15,
+            1e16, 1e17, 1e18, 1e19, 1e20, 1e21, 1e22, 0., 0., 0., 0., 0., 0., 0., 0., 0.,
+        ];
+        TABLE[exponent & 31]
+    }
+
+    #[inline]
+    fn from_u64(v: u64) -> Self {
+        debug_assert!(v <= Self::MAX_MANTISSA_FAST_PATH);
+        v as _
+    }
+}
 
 #[inline]
 pub(super) fn pfe_empty() -> ParseFloatError {

library/core/src/num/imp/dec2flt/parse.rs

@@ -2,9 +2,8 @@
 
 use dec2flt::common::{ByteSlice, is_8digits};
 use dec2flt::decimal::Decimal;
-use dec2flt::float::Float;
 
-use crate::num::imp::dec2flt;
+use crate::num::imp::{Float, dec2flt};
 
 const MIN_19DIGIT_INT: u64 = 100_0000_0000_0000_0000;
 

library/core/src/num/imp/dec2flt/slow.rs

@@ -2,9 +2,8 @@
 
 use dec2flt::common::BiasedFp;
 use dec2flt::decimal_seq::{DecimalSeq, parse_decimal_seq};
-use dec2flt::float::Float;
 
-use crate::num::imp::dec2flt;
+use crate::num::imp::{Float, dec2flt};
 
 /// Parse the significant digits and biased, binary exponent of a float.
 ///

library/core/src/num/imp/flt2dec/decoder.rs

@@ -1,7 +1,7 @@
 //! Decodes a floating-point value into individual parts and error ranges.
 
 use crate::num::FpCategory;
-use crate::num::imp::dec2flt::float::FloatExt;
+use crate::num::imp::FloatExt;
 
 /// Decoded unsigned finite value, such that:
 ///

library/core/src/num/imp/mod.rs

@@ -16,3 +16,6 @@
 pub(crate) mod int_sqrt;
 pub(crate) mod libm;
 pub(crate) mod overflow_panic;
+mod traits;
+
+pub use traits::{Float, FloatExt, Int};

library/core/src/num/imp/traits.rs

@@ -1,10 +1,14 @@
-//! Helper trait for generic float types.
+//! Numeric traits used for internal implementations.
 
-use core::f64;
+#![doc(hidden)]
+#![unstable(
+    feature = "num_internals",
+    reason = "internal routines only exposed for testing",
+    issue = "none"
+)]
 
-use crate::fmt::{Debug, LowerExp};
 use crate::num::FpCategory;
-use crate::ops::{self, Add, Div, Mul, Neg};
+use crate::{f64, fmt, ops};
 
 /// Lossy `as` casting between two types.
 pub trait CastInto<T: Copy>: Copy {
@@ -16,7 +20,7 @@ pub trait Int:
     Sized
     + Clone
     + Copy
-    + Debug
+    + fmt::Debug
     + ops::Shr<u32, Output = Self>
     + ops::Shl<u32, Output = Self>
     + ops::BitAnd<Output = Self>
@@ -51,17 +55,16 @@ impl Int for $ty {
 #[doc(hidden)]
 pub trait Float:
     Sized
-    + Div<Output = Self>
-    + Neg<Output = Self>
-    + Mul<Output = Self>
-    + Add<Output = Self>
-    + LowerExp
+    + ops::Div<Output = Self>
+    + ops::Neg<Output = Self>
+    + ops::Mul<Output = Self>
+    + ops::Add<Output = Self>
+    + fmt::Debug
     + PartialEq
     + PartialOrd
     + Default
     + Clone
     + Copy
-    + Debug
 {
     /// The unsigned integer with the same size as the float
     type Int: Int + Into<u64>;
@@ -184,41 +187,6 @@ fn integer_decode(self) -> (u64, i16, i8) {
     }
 }
 
-/// Extension to `Float` that are necessary for parsing using the Lemire method.
-///
-/// See the parent module's doc comment for why this is necessary.
-///
-/// Not intended for use outside of the `dec2flt` module.
-#[doc(hidden)]
-pub trait Lemire: FloatExt {
-    /// Maximum exponent for a fast path case, or `⌊(SIG_BITS+1)/log2(5)⌋`
-    // assuming FLT_EVAL_METHOD = 0
-    const MAX_EXPONENT_FAST_PATH: i64 = {
-        let log2_5 = f64::consts::LOG2_10 - 1.0;
-        (Self::SIG_TOTAL_BITS as f64 / log2_5) as i64
-    };
-
-    /// Minimum exponent for a fast path case, or `-⌊(SIG_BITS+1)/log2(5)⌋`
-    const MIN_EXPONENT_FAST_PATH: i64 = -Self::MAX_EXPONENT_FAST_PATH;
-
-    /// Maximum exponent that can be represented for a disguised-fast path case.
-    /// This is `MAX_EXPONENT_FAST_PATH + ⌊(SIG_BITS+1)/log2(10)⌋`
-    const MAX_EXPONENT_DISGUISED_FAST_PATH: i64 =
-        Self::MAX_EXPONENT_FAST_PATH + (Self::SIG_TOTAL_BITS as f64 / f64::consts::LOG2_10) as i64;
-
-    /// Maximum mantissa for the fast-path (`1 << 53` for f64).
-    const MAX_MANTISSA_FAST_PATH: u64 = 1 << Self::SIG_TOTAL_BITS;
-
-    /// Gets a small power-of-ten for fast-path multiplication.
-    fn pow10_fast_path(exponent: usize) -> Self;
-
-    /// Converts integer into float through an as cast.
-    /// This is only called in the fast-path algorithm, and therefore
-    /// will not lose precision, since the value will always have
-    /// only if the value is <= Self::MAX_MANTISSA_FAST_PATH.
-    fn from_u64(v: u64) -> Self;
-}
-
 /// Solve for `b` in `10^b = 2^a`
 const fn pow2_to_pow10(a: i64) -> i64 {
     let res = (a as f64) / f64::consts::LOG2_10;
@@ -260,21 +228,6 @@ fn from_u64_bits(v: u64) -> Self {
     }
 }
 
-#[cfg(target_has_reliable_f16)]
-impl Lemire for f16 {
-    fn pow10_fast_path(exponent: usize) -> Self {
-        #[allow(clippy::use_self)]
-        const TABLE: [f16; 8] = [1e0, 1e1, 1e2, 1e3, 1e4, 0.0, 0.0, 0.];
-        TABLE[exponent & 7]
-    }
-
-    #[inline]
-    fn from_u64(v: u64) -> Self {
-        debug_assert!(v <= Self::MAX_MANTISSA_FAST_PATH);
-        v as _
-    }
-}
-
 impl Float for f32 {
     type Int = u32;
 
@@ -308,21 +261,6 @@ fn from_u64_bits(v: u64) -> Self {
     }
 }
 
-impl Lemire for f32 {
-    fn pow10_fast_path(exponent: usize) -> Self {
-        #[allow(clippy::use_self)]
-        const TABLE: [f32; 16] =
-            [1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9, 1e10, 0., 0., 0., 0., 0.];
-        TABLE[exponent & 15]
-    }
-
-    #[inline]
-    fn from_u64(v: u64) -> Self {
-        debug_assert!(v <= Self::MAX_MANTISSA_FAST_PATH);
-        v as _
-    }
-}
-
 impl Float for f64 {
     type Int = u64;
 
@@ -355,19 +293,3 @@ fn from_u64_bits(v: u64) -> Self {
         f64::from_bits(v)
     }
 }
-
-impl Lemire for f64 {
-    fn pow10_fast_path(exponent: usize) -> Self {
-        const TABLE: [f64; 32] = [
-            1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9, 1e10, 1e11, 1e12, 1e13, 1e14, 1e15,
-            1e16, 1e17, 1e18, 1e19, 1e20, 1e21, 1e22, 0., 0., 0., 0., 0., 0., 0., 0., 0.,
-        ];
-        TABLE[exponent & 31]
-    }
-
-    #[inline]
-    fn from_u64(v: u64) -> Self {
-        debug_assert!(v <= Self::MAX_MANTISSA_FAST_PATH);
-        v as _
-    }
-}

library/coretests/tests/lib.rs

@@ -88,6 +88,7 @@
 #![feature(next_index)]
 #![feature(non_exhaustive_omitted_patterns_lint)]
 #![feature(nonzero_from_str_radix)]
+#![feature(num_internals)]
 #![feature(numfmt)]
 #![feature(one_sided_range)]
 #![feature(panic_internals)]

library/coretests/tests/num/dec2flt/float.rs

@@ -1,4 +1,5 @@
-use core::num::imp::dec2flt::float::{Float, FloatExt, Lemire};
+use core::num::imp::dec2flt::Lemire;
+use core::num::imp::{Float, FloatExt};
 
 use crate::num::{ldexp_f32, ldexp_f64};
 

library/coretests/tests/num/dec2flt/lemire.rs

@@ -1,6 +1,5 @@
-use core::num::imp::dec2flt;
+use core::num::imp::{Float, dec2flt};
 
-use dec2flt::float::Float;
 use dec2flt::lemire::compute_float;
 
 #[cfg(target_has_reliable_f16)]