Skip to content

Explicitly extend Base functions (Base.foo(...) = ...) instead of imports. #52

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 5 commits into from
Apr 19, 2020
Merged

Explicitly extend Base functions (Base.foo(...) = ...) instead of imports. #52

Changes from 2 commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
5877a58
Explicitly extend Base functions (Base.foo(...) = ...) instead of imp…
NHDaly Feb 1, 2020
317c82b
Remove unsafe `@pure`: for max_exp10, `@eval` in a loop instead
NHDaly Feb 1, 2020
685b3dc
Update src/FixedPointDecimals.jl
NHDaly Apr 19, 2020
9949f40
Import Base at-pure to simplify FixedPointDecimals.jl file.
NHDaly Apr 19, 2020
a2b442e
Remove bit-rotted comment about at-pure for max_exp10
NHDaly Apr 19, 2020
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
132 changes: 69 additions & 63 deletions src/FixedPointDecimals.jl
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -27,13 +27,7 @@ module FixedPointDecimals

export FixedDecimal, RoundThrows

import Base: reinterpret, zero, one, abs, sign, ==, <, <=, +, -, /, *, div, rem, divrem,
fld, mod, fldmod, fld1, mod1, fldmod1, isinteger, typemin, typemax,
print, show, string, convert, parse, promote_rule, min, max,
floatmin, floatmax, trunc, round, floor, ceil, eps, float, widemul, decompose

const BitInteger = Union{Int8, UInt8, Int16, UInt16, Int32, UInt32, Int64,
UInt64, Int128, UInt128}
using Base: decompose, BitInteger

# floats that support fma and are roughly IEEE-like
const FMAFloat = Union{Float16, Float32, Float64, BigFloat}
Expand Down Expand Up @@ -114,22 +108,22 @@ floattype(::Type{<:FD{T}}) where {T<:Integer} = Float64
floattype(::Type{<:FD{BigInt}}) = BigFloat

# basic operators
-(x::FD{T, f}) where {T, f} = reinterpret(FD{T, f}, -x.i)
abs(x::FD{T, f}) where {T, f} = reinterpret(FD{T, f}, abs(x.i))
Base.:-(x::FD{T, f}) where {T, f} = reinterpret(FD{T, f}, -x.i)
Base.abs(x::FD{T, f}) where {T, f} = reinterpret(FD{T, f}, abs(x.i))

+(x::FD{T, f}, y::FD{T, f}) where {T, f} = reinterpret(FD{T, f}, x.i+y.i)
-(x::FD{T, f}, y::FD{T, f}) where {T, f} = reinterpret(FD{T, f}, x.i-y.i)
Base.:+(x::FD{T, f}, y::FD{T, f}) where {T, f} = reinterpret(FD{T, f}, x.i+y.i)
Base.:-(x::FD{T, f}, y::FD{T, f}) where {T, f} = reinterpret(FD{T, f}, x.i-y.i)

# wide multiplication
Base.@pure function widemul(x::FD{<:Any, f}, y::FD{<:Any, g}) where {f, g}
Base.@pure function Base.widemul(x::FD{<:Any, f}, y::FD{<:Any, g}) where {f, g}
i = widemul(x.i, y.i)
reinterpret(FD{typeof(i), f + g}, i)
end
Base.@pure function widemul(x::FD{T, f}, y::Integer) where {T, f}
Base.@pure function Base.widemul(x::FD{T, f}, y::Integer) where {T, f}
i = widemul(x.i, y)
reinterpret(FD{typeof(i), f}, i)
end
Base.@pure widemul(x::Integer, y::FD) = widemul(y, x)
Base.@pure Base.widemul(x::Integer, y::FD) = widemul(y, x)

"""
_round_to_even(quotient, remainder, divisor)
Expand Down Expand Up @@ -160,48 +154,48 @@ _round_to_even(q, r, d) = _round_to_even(promote(q, r, d)...)
# multiplication rounds to nearest even representation
# TODO: can we use floating point to speed this up? after we build a
# correctness test suite.
function *(x::FD{T, f}, y::FD{T, f}) where {T, f}
function Base.:*(x::FD{T, f}, y::FD{T, f}) where {T, f}
powt = coefficient(FD{T, f})
quotient, remainder = fldmodinline(widemul(x.i, y.i), powt)
reinterpret(FD{T, f}, _round_to_even(quotient, remainder, powt))
end

# these functions are needed to avoid InexactError when converting from the
# integer type
*(x::Integer, y::FD{T, f}) where {T, f} = reinterpret(FD{T, f}, T(x * y.i))
*(x::FD{T, f}, y::Integer) where {T, f} = reinterpret(FD{T, f}, T(x.i * y))
Base.:*(x::Integer, y::FD{T, f}) where {T, f} = reinterpret(FD{T, f}, T(x * y.i))
Base.:*(x::FD{T, f}, y::Integer) where {T, f} = reinterpret(FD{T, f}, T(x.i * y))

function /(x::FD{T, f}, y::FD{T, f}) where {T, f}
function Base.:/(x::FD{T, f}, y::FD{T, f}) where {T, f}
powt = coefficient(FD{T, f})
quotient, remainder = fldmod(widemul(x.i, powt), y.i)
reinterpret(FD{T, f}, T(_round_to_even(quotient, remainder, y.i)))
end

# These functions allow us to perform division with integers outside of the range of the
# FixedDecimal.
function /(x::Integer, y::FD{T, f}) where {T, f}
function Base.:/(x::Integer, y::FD{T, f}) where {T, f}
powt = coefficient(FD{T, f})
powtsq = widemul(powt, powt)
quotient, remainder = fldmod(widemul(x, powtsq), y.i)
reinterpret(FD{T, f}, T(_round_to_even(quotient, remainder, y.i)))
end

function /(x::FD{T, f}, y::Integer) where {T, f}
function Base.:/(x::FD{T, f}, y::Integer) where {T, f}
quotient, remainder = fldmod(x.i, y)
reinterpret(FD{T, f}, T(_round_to_even(quotient, remainder, y)))
end

# integerification
trunc(x::FD{T, f}) where {T, f} = FD{T, f}(div(x.i, coefficient(FD{T, f})))
floor(x::FD{T, f}) where {T, f} = FD{T, f}(fld(x.i, coefficient(FD{T, f})))
Base.trunc(x::FD{T, f}) where {T, f} = FD{T, f}(div(x.i, coefficient(FD{T, f})))
Base.floor(x::FD{T, f}) where {T, f} = FD{T, f}(fld(x.i, coefficient(FD{T, f})))

# TODO: round with number of digits; should be easy
function round(x::FD{T, f}, ::RoundingMode{:Nearest}=RoundNearest) where {T, f}
function Base.round(x::FD{T, f}, ::RoundingMode{:Nearest}=RoundNearest) where {T, f}
powt = coefficient(FD{T, f})
quotient, remainder = fldmodinline(x.i, powt)
FD{T, f}(_round_to_even(quotient, remainder, powt))
end
function ceil(x::FD{T, f}) where {T, f}
function Base.ceil(x::FD{T, f}) where {T, f}
powt = coefficient(FD{T, f})
quotient, remainder = fldmodinline(x.i, powt)
if remainder > 0
Expand Down Expand Up @@ -243,44 +237,44 @@ end
_apply_exact_float(f, ::Type{T}, x::Real, i::Integer) where T = f(T, x, i)

for fn in [:trunc, :floor, :ceil]
@eval ($fn(::Type{TI}, x::FD)::TI) where {TI <: Integer} = $fn(x)
@eval (Base.$fn(::Type{TI}, x::FD)::TI) where {TI <: Integer} = $fn(x)

# round/trunc/ceil/flooring to FD; generic
@eval function $fn(::Type{FD{T, f}}, x::Real) where {T, f}
@eval function Base.$fn(::Type{FD{T, f}}, x::Real) where {T, f}
powt = coefficient(FD{T, f})
# Use machine Float64 if possible, but fall back to BigFloat if we need
# more precision. 4f bits suffices.
val = _apply_exact_float($(Symbol(fn, "mul")), T, x, powt)
reinterpret(FD{T, f}, val)
end
end
function round(::Type{TI}, x::FD, ::RoundingMode{:Nearest}=RoundNearest) where {TI <: Integer}
function Base.round(::Type{TI}, x::FD, ::RoundingMode{:Nearest}=RoundNearest) where {TI <: Integer}
convert(TI, round(x))::TI
end
function round(::Type{FD{T, f}}, x::Real, ::RoundingMode{:Nearest}=RoundNearest) where {T, f}
function Base.round(::Type{FD{T, f}}, x::Real, ::RoundingMode{:Nearest}=RoundNearest) where {T, f}
reinterpret(FD{T, f}, round(T, x * coefficient(FD{T, f})))
end

# needed to avoid ambiguity
function round(::Type{FD{T, f}}, x::Rational, ::RoundingMode{:Nearest}=RoundNearest) where {T, f}
function Base.round(::Type{FD{T, f}}, x::Rational, ::RoundingMode{:Nearest}=RoundNearest) where {T, f}
reinterpret(FD{T, f}, round(T, x * coefficient(FD{T, f})))
end

# conversions and promotions
convert(::Type{FD{T, f}}, x::FD{T, f}) where {T, f} = x # Converting an FD to itself is a no-op
Base.convert(::Type{FD{T, f}}, x::FD{T, f}) where {T, f} = x # Converting an FD to itself is a no-op

function convert(::Type{FD{T, f}}, x::Integer) where {T, f}
function Base.convert(::Type{FD{T, f}}, x::Integer) where {T, f}
reinterpret(FD{T, f}, T(widemul(x, coefficient(FD{T, f}))))
end

convert(::Type{T}, x::AbstractFloat) where {T <: FD} = round(T, x)
Base.convert(::Type{T}, x::AbstractFloat) where {T <: FD} = round(T, x)

function convert(::Type{FD{T, f}}, x::Rational) where {T, f}
function Base.convert(::Type{FD{T, f}}, x::Rational) where {T, f}
powt = coefficient(FD{T, f})
reinterpret(FD{T, f}, T(x * powt))::FD{T, f}
end

function convert(::Type{FD{T, f}}, x::FD{U, g}) where {T, f, U, g}
function Base.convert(::Type{FD{T, f}}, x::FD{U, g}) where {T, f, U, g}
if f ≥ g
# Compute `10^(f - g)` without overflow
powt = div(coefficient(FD{T, f}), coefficient(FD{U, g}))
Expand All @@ -298,7 +292,7 @@ function convert(::Type{FD{T, f}}, x::FD{U, g}) where {T, f, U, g}
end

for remfn in [:rem, :mod, :mod1, :min, :max]
@eval $remfn(x::T, y::T) where {T <: FD} = reinterpret(T, $remfn(x.i, y.i))
@eval Base.$remfn(x::T, y::T) where {T <: FD} = reinterpret(T, $remfn(x.i, y.i))
end
# TODO: When we upgrade to a min julia version >=1.4 (i.e Julia 2.0), this block can be
# dropped in favor of three-argument `div`, below.
Expand All @@ -313,33 +307,33 @@ if VERSION >= v"1.4.0-"
Base.div(x::T, y::T, r::RoundingMode) where {T <: FD} = T(div(x.i, y.i, r))
end

convert(::Type{AbstractFloat}, x::FD) = convert(floattype(typeof(x)), x)
function convert(::Type{TF}, x::FD{T, f}) where {TF <: AbstractFloat, T, f}
Base.convert(::Type{AbstractFloat}, x::FD) = convert(floattype(typeof(x)), x)
function Base.convert(::Type{TF}, x::FD{T, f}) where {TF <: AbstractFloat, T, f}
convert(TF, x.i / coefficient(FD{T, f}))::TF
end

function convert(::Type{TF}, x::FD{T, f}) where {TF <: BigFloat, T, f}
function Base.convert(::Type{TF}, x::FD{T, f}) where {TF <: BigFloat, T, f}
convert(TF, BigInt(x.i) / BigInt(coefficient(FD{T, f})))::TF
end

function convert(::Type{TI}, x::FD{T, f}) where {TI <: Integer, T, f}
function Base.convert(::Type{TI}, x::FD{T, f}) where {TI <: Integer, T, f}
isinteger(x) || throw(InexactError(:convert, TI, x))
convert(TI, div(x.i, coefficient(FD{T, f})))::TI
end

function convert(::Type{TR}, x::FD{T, f}) where {TR <: Rational, T, f}
function Base.convert(::Type{TR}, x::FD{T, f}) where {TR <: Rational, T, f}
convert(TR, x.i // coefficient(FD{T, f}))::TR
end

(::Type{T})(x::FD) where {T<:Union{AbstractFloat,Integer,Rational}} = convert(T, x)

promote_rule(::Type{FD{T, f}}, ::Type{<:Integer}) where {T, f} = FD{T, f}
promote_rule(::Type{<:FD}, ::Type{TF}) where {TF <: AbstractFloat} = TF
promote_rule(::Type{<:FD}, ::Type{Rational{TR}}) where {TR} = Rational{TR}
Base.promote_rule(::Type{FD{T, f}}, ::Type{<:Integer}) where {T, f} = FD{T, f}
Base.promote_rule(::Type{<:FD}, ::Type{TF}) where {TF <: AbstractFloat} = TF
Base.promote_rule(::Type{<:FD}, ::Type{Rational{TR}}) where {TR} = Rational{TR}

# TODO: decide if these are the right semantics;
# right now we pick the bigger int type and the bigger decimal point
Base.@pure function promote_rule(::Type{FD{T, f}}, ::Type{FD{U, g}}) where {T, f, U, g}
Base.@pure function Base.promote_rule(::Type{FD{T, f}}, ::Type{FD{U, g}}) where {T, f, U, g}
FD{promote_type(T, U), max(f, g)}
end

Expand All @@ -348,24 +342,24 @@ Base.zero(::Type{FD{T, f}}) where {T, f} = reinterpret(FD{T, f}, zero(T))
Base.one(::Type{FD{T, f}}) where {T, f} = reinterpret(FD{T, f}, coefficient(FD{T, f}))

# comparison
==(x::T, y::T) where {T <: FD} = x.i == y.i
<(x::T, y::T) where {T <: FD} = x.i < y.i
<=(x::T, y::T) where {T <: FD} = x.i <= y.i
Base.:(==)(x::T, y::T) where {T <: FD} = x.i == y.i
Base.:( <)(x::T, y::T) where {T <: FD} = x.i < y.i
Base.:(<=)(x::T, y::T) where {T <: FD} = x.i <= y.i

# predicates and traits
isinteger(x::FD{T, f}) where {T, f} = rem(x.i, coefficient(FD{T, f})) == 0
typemin(::Type{FD{T, f}}) where {T, f} = reinterpret(FD{T, f}, typemin(T))
typemax(::Type{FD{T, f}}) where {T, f}= reinterpret(FD{T, f}, typemax(T))
eps(::Type{T}) where {T <: FD} = reinterpret(T, 1)
eps(x::FD) = eps(typeof(x))
floatmin(::Type{T}) where {T <: FD} = eps(T)
floatmax(::Type{T}) where {T <: FD} = typemax(T)
Base.isinteger(x::FD{T, f}) where {T, f} = rem(x.i, coefficient(FD{T, f})) == 0
Base.typemin(::Type{FD{T, f}}) where {T, f} = reinterpret(FD{T, f}, typemin(T))
Base.typemax(::Type{FD{T, f}}) where {T, f}= reinterpret(FD{T, f}, typemax(T))
Base.eps(::Type{T}) where {T <: FD} = reinterpret(T, 1)
Base.eps(x::FD) = eps(typeof(x))
Base.floatmin(::Type{T}) where {T <: FD} = eps(T)
Base.floatmax(::Type{T}) where {T <: FD} = typemax(T)

# printing
function print(io::IO, x::FD{T, 0}) where T
function Base.print(io::IO, x::FD{T, 0}) where T
print(io, x.i)
end
function print(io::IO, x::FD{T, f}) where {T, f}
function Base.print(io::IO, x::FD{T, f}) where {T, f}
iscompact = get(io, :compact, false)

# note: a is negative if x.i == typemin(x.i)
Expand All @@ -387,7 +381,7 @@ function print(io::IO, x::FD{T, f}) where {T, f}
print(io, integer, '.', fractionchars)
end

function show(io::IO, x::FD{T, f}) where {T, f}
function Base.show(io::IO, x::FD{T, f}) where {T, f}
iscompact = get(io, :compact, false)
if !iscompact
print(io, "FixedDecimal{$T,$f}(")
Expand All @@ -407,7 +401,7 @@ Raises an `InexactError` if any rounding is necessary.
"""
const RoundThrows = RoundingMode{:Throw}()

function parse(::Type{FD{T, f}}, str::AbstractString, mode::RoundingMode=RoundNearest) where {T, f}
function Base.parse(::Type{FD{T, f}}, str::AbstractString, mode::RoundingMode=RoundNearest) where {T, f}
if !(mode in [RoundThrows, RoundNearest, RoundToZero])
throw(ArgumentError("Unhandled rounding mode $mode"))
end
Expand Down Expand Up @@ -475,8 +469,17 @@ end

The highest value of `x` which does not result in an overflow when evaluating `T(10)^x`. For
types of `T` that do not overflow -1 will be returned.

NOTE: This function is expensive, since it contains a while-loop, but it is actually
computing a constant value for types, so it really only needs to be run once per type.
We achieve this by `@eval`ing new methods in a loop, below. Users can do this
themselves to add more "frozen" methods for custom Integer types:
```julia
@eval FixedPointDecimals.max_exp10(::Type{CustomIntType}) = \$(max_exp10(CustomIntType))
```
This function does not have or depend on any side-effects.
"""
Base.@pure function max_exp10(::Type{T}) where {T <: Integer}
function max_exp10(::Type{T}) where {T <: Integer}
# This function is marked as `Base.@pure`. Even though it does call some generic
Copy link
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

comment has bitrotted

Copy link
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

other than this, LGTM

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Oops. I don't think i actually meant for this change to be part of this PR... BUT i guess it doesn't hurt. It is definitely an improvement, so i'll just carry it along. Sorry about that; thanks for the careful review.

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Fixed comment. Done.

# functions, they are all simple methods that should be able to be evaluated as
# constants. This function does not have or depend on any side-effects.
Expand All @@ -497,9 +500,12 @@ Base.@pure function max_exp10(::Type{T}) where {T <: Integer}
end

max_exp10(::Type{BigInt}) = -1
# Freeze the evaluation for Int128, since max_exp10(Int128) is too compilicated to get
# optimized away by the compiler during const-folding.
@eval max_exp10(::Type{Int128}) = $(max_exp10(Int128))
# Freeze the evaluation for BitInteger types, since max_exp10() is too compilicated to get
# optimized away by the compiler during const-folding. (We can't freeze for user-defined
# types because we don't know what they are yet.)
for T in Base.BitInteger_types
@eval max_exp10(::Type{$T}) = $(max_exp10(T))
end

# coefficient is marked pure. This is needed to ensure that the result is always available
# at compile time, and can therefore be used when optimizing mathematical operations.
Expand All @@ -514,6 +520,6 @@ Base.@pure coefficient(fd::FD{T, f}) where {T, f} = coefficient(FD{T, f})
value(fd::FD) = fd.i

# for generic hashing
decompose(fd::FD) = decompose(Rational(fd))
Base.decompose(fd::FD) = decompose(Rational(fd))

end