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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use std::cmp::Ordering;
use std::hash;
use std::mem::transmute;
use super::err::*;
#[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
pub enum ConstFloat {
F32(f32),
F64(f64),
// When the type isn't known, we have to operate on both possibilities.
FInfer {
f32: f32,
f64: f64
}
}
pub use self::ConstFloat::*;
impl ConstFloat {
/// Description of the type, not the value
pub fn description(&self) -> &'static str {
match *self {
FInfer {..} => "float",
F32(_) => "f32",
F64(_) => "f64",
}
}
pub fn is_nan(&self) -> bool {
match *self {
F32(f) => f.is_nan(),
F64(f) => f.is_nan(),
FInfer { f32, f64 } => f32.is_nan() || f64.is_nan()
}
}
/// Compares the values if they are of the same type
pub fn try_cmp(self, rhs: Self) -> Result<Ordering, ConstMathErr> {
match (self, rhs) {
(F64(a), F64(b)) |
(F64(a), FInfer { f64: b, .. }) |
(FInfer { f64: a, .. }, F64(b)) |
(FInfer { f64: a, .. }, FInfer { f64: b, .. }) => {
// This is pretty bad but it is the existing behavior.
Ok(if a == b {
Ordering::Equal
} else if a < b {
Ordering::Less
} else {
Ordering::Greater
})
}
(F32(a), F32(b)) |
(F32(a), FInfer { f32: b, .. }) |
(FInfer { f32: a, .. }, F32(b)) => {
Ok(if a == b {
Ordering::Equal
} else if a < b {
Ordering::Less
} else {
Ordering::Greater
})
}
_ => Err(CmpBetweenUnequalTypes),
}
}
}
/// Note that equality for `ConstFloat` means that the it is the same
/// constant, not that the rust values are equal. In particular, `NaN
/// == NaN` (at least if it's the same NaN; distinct encodings for NaN
/// are considering unequal).
impl PartialEq for ConstFloat {
fn eq(&self, other: &Self) -> bool {
match (*self, *other) {
(F64(a), F64(b)) |
(F64(a), FInfer { f64: b, .. }) |
(FInfer { f64: a, .. }, F64(b)) |
(FInfer { f64: a, .. }, FInfer { f64: b, .. }) => {
unsafe{transmute::<_,u64>(a) == transmute::<_,u64>(b)}
}
(F32(a), F32(b)) => {
unsafe{transmute::<_,u32>(a) == transmute::<_,u32>(b)}
}
_ => false
}
}
}
impl Eq for ConstFloat {}
impl hash::Hash for ConstFloat {
fn hash<H: hash::Hasher>(&self, state: &mut H) {
match *self {
F64(a) | FInfer { f64: a, .. } => {
unsafe { transmute::<_,u64>(a) }.hash(state)
}
F32(a) => {
unsafe { transmute::<_,u32>(a) }.hash(state)
}
}
}
}
impl ::std::fmt::Display for ConstFloat {
fn fmt(&self, fmt: &mut ::std::fmt::Formatter) -> Result<(), ::std::fmt::Error> {
match *self {
FInfer { f64, .. } => write!(fmt, "{}", f64),
F32(f) => write!(fmt, "{}f32", f),
F64(f) => write!(fmt, "{}f64", f),
}
}
}
macro_rules! derive_binop {
($op:ident, $func:ident) => {
impl ::std::ops::$op for ConstFloat {
type Output = Result<Self, ConstMathErr>;
fn $func(self, rhs: Self) -> Result<Self, ConstMathErr> {
match (self, rhs) {
(F32(a), F32(b)) |
(F32(a), FInfer { f32: b, .. }) |
(FInfer { f32: a, .. }, F32(b)) => Ok(F32(a.$func(b))),
(F64(a), F64(b)) |
(FInfer { f64: a, .. }, F64(b)) |
(F64(a), FInfer { f64: b, .. }) => Ok(F64(a.$func(b))),
(FInfer { f32: a32, f64: a64 },
FInfer { f32: b32, f64: b64 }) => Ok(FInfer {
f32: a32.$func(b32),
f64: a64.$func(b64)
}),
_ => Err(UnequalTypes(Op::$op)),
}
}
}
}
}
derive_binop!(Add, add);
derive_binop!(Sub, sub);
derive_binop!(Mul, mul);
derive_binop!(Div, div);
derive_binop!(Rem, rem);
impl ::std::ops::Neg for ConstFloat {
type Output = Self;
fn neg(self) -> Self {
match self {
F32(f) => F32(-f),
F64(f) => F64(-f),
FInfer { f32, f64 } => FInfer {
f32: -f32,
f64: -f64
}
}
}
}
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