Switch float printing from grisu to ryu algorithm

Author: quinnj

LICENSE.md

@@ -39,6 +39,7 @@ Julia includes code from the following projects, which have their own licenses:
 
 The following components included in Julia `Base` have their own separate licenses:
 
+- base/ryu/* [Boost] (see [ryu](https://github.com/ulfjack/ryu/blob/master/LICENSE-Boost))
 - base/grisu/* [BSD-3] (see [double-conversion](https://github.com/google/double-conversion/blob/master/LICENSE))
 - base/special/{exp,rem_pio2,hyperbolic}.jl [Freely distributable with preserved copyright notice] (see [FDLIBM](https://www.netlib.org/fdlibm))
 

base/Base.jl

@@ -303,10 +303,15 @@ function deepcopy_internal end
 include("Enums.jl")
 using .Enums
 
-# BigInts and BigFloats
+# BigInts
 include("gmp.jl")
 using .GMP
 
+# float printing: requires BigInt
+include("ryu/Ryu.jl")
+using .Ryu
+
+# BigFloats
 include("mpfr.jl")
 using .MPFR
 

base/docs/basedocs.jl

@@ -1059,10 +1059,10 @@ Create a `Float32` from `x`. If `x` is not exactly representable then `mode` det
 # Examples
 ```jldoctest
 julia> Float32(1/3, RoundDown)
-0.3333333f0
+0.3333333
 
 julia> Float32(1/3, RoundUp)
-0.33333334f0
+0.33333334
 ```
 
 See [`RoundingMode`](@ref) for available rounding modes.

base/essentials.jl

@@ -141,7 +141,7 @@ julia> x = 1/3
 0.3333333333333333
 
 julia> convert(Float32, x)
-0.33333334f0
+0.33333334
 
 julia> convert(Rational{Int32}, x)
 1//3
@@ -402,11 +402,11 @@ For example,
 # Examples
 ```jldoctest
 julia> reinterpret(Float32, UInt32(7))
-1.0f-44
+1.0e-44
 
 julia> reinterpret(Float32, UInt32[1 2 3 4 5])
 1×5 reinterpret(Float32, ::Array{UInt32,2}):
- 1.4013e-45  2.8026e-45  4.2039e-45  5.60519e-45  7.00649e-45
+ 1.0e-45  3.0e-45  4.0e-45  6.0e-45  7.0e-45
 ```
 """
 reinterpret(::Type{T}, x) where {T} = bitcast(T, x)

base/float.jl

@@ -764,10 +764,10 @@ The highest finite value representable by the given floating-point DataType `T`.
 # Examples
 ```jldoctest
 julia> floatmax(Float16)
-Float16(6.55e4)
+65500.0
 
 julia> floatmax(Float32)
-3.4028235f38
+3.4028235e38
 ```
 """
 floatmax(x::T) where {T<:AbstractFloat} = floatmax(T)
@@ -790,7 +790,7 @@ julia> eps()
 2.220446049250313e-16
 
 julia> eps(Float32)
-1.1920929f-7
+1.1920929e-7
 
 julia> 1.0 + eps()
 1.0000000000000002

base/grisu/grisu.jl

@@ -154,31 +154,6 @@ function _show(io::IO, x::AbstractFloat, mode, n::Int, typed, compact)
     nothing
 end
 
-function Base.show(io::IO, x::Union{Float64,Float32})
-    if get(io, :compact, false)
-        _show(io, x, PRECISION, 6, x isa Float64, true)
-    else
-        _show(io, x, SHORTEST, 0, get(io, :typeinfo, Any) !== typeof(x), false)
-    end
-end
-
-function Base.show(io::IO, x::Float16)
-    hastypeinfo = Float16 === get(io, :typeinfo, Any)
-    # if hastypeinfo, the printing would be more compact using `SHORTEST`
-    # while still retaining all the information
-    # BUT: we want to print all digits in `show`, not in display, so we rely
-    # on the :compact property to make the decision
-    # (cf. https://github.com/JuliaLang/julia/pull/24651#issuecomment-345535687)
-    if get(io, :compact, false) && !hastypeinfo
-        _show(io, x, PRECISION, 5, false, true)
-    else
-        _show(io, x, SHORTEST, 0, !hastypeinfo, false)
-    end
-end
-
-Base.print(io::IO, x::Float32) = _show(io, x, SHORTEST, 0, false, false)
-Base.print(io::IO, x::Float16) = _show(io, x, SHORTEST, 0, false, false)
-
 # normal:
 #   0 < pt < len        ####.####           len+1
 #   pt <= 0             0.000########       len-pt+1

base/int.jl

@@ -638,10 +638,10 @@ The lowest value representable by the given (real) numeric DataType `T`.
 # Examples
 ```jldoctest
 julia> typemin(Float16)
--Inf16
+-Inf
 
 julia> typemin(Float32)
--Inf32
+-Inf
 ```
 """
 function typemin end

base/promotion.jl

@@ -250,7 +250,7 @@ If no arguments can be converted, an error is raised.
 # Examples
 ```jldoctest
 julia> promote(Int8(1), Float16(4.5), Float32(4.1))
-(1.0f0, 4.5f0, 4.1f0)
+(1.0, 4.5, 4.1)
 ```
 """
 function promote end

base/ryu/LICENSE.md

@@ -0,0 +1,25 @@
+The code in this directory (base/ryu) is a derivative based on the work in the https://github.com/ulfjack/ryu repository, which allows the use of the Boost software license, included below.
+
+Boost Software License - Version 1.0 - August 17th, 2003
+
+Permission is hereby granted, free of charge, to any person or organization
+obtaining a copy of the software and accompanying documentation covered by
+this license (the "Software") to use, reproduce, display, distribute,
+execute, and transmit the Software, and to prepare derivative works of the
+Software, and to permit third-parties to whom the Software is furnished to
+do so, all subject to the following:
+
+The copyright notices in the Software and this entire statement, including
+the above license grant, this restriction and the following disclaimer,
+must be included in all copies of the Software, in whole or in part, and
+all derivative works of the Software, unless such copies or derivative
+works are solely in the form of machine-executable object code generated by
+a source language processor.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.

base/ryu/Ryu.jl

@@ -0,0 +1,99 @@
+module Ryu
+
+include("utils.jl")
+include("shortest.jl")
+include("fixed.jl")
+include("exp.jl")
+
+neededdigits(::Type{Float64}) = 309 + 17
+neededdigits(::Type{Float32}) = 39 + 9
+neededdigits(::Type{Float16}) = 9 + 5
+
+"""
+    Ryu.writeshortest(x, plus=false, space=false, hash=true, precision=-1, expchar=UInt8('e'), padexp=false, decchar=UInt8('.'))
+    Ryu.writeshortest(buf::Vector{UInt8}, pos::Int, x, args...)
+
+Convert a float value `x` into its "shortest" decimal string, which can be parsed back to the same value.
+This function allows achieving the `%g` printf format.
+Note the 2nd method allows passing in a byte buffer and position directly; callers must ensure the buffer has sufficient room to hold the entire decimal string.
+
+Various options for the output format include:
+  * `plus`: for positive `x`, prefix decimal string with a `'+'` character
+  * `space`: for positive `x`, prefix decimal string with a `' '` character; overridden if `plus=true`
+  * `hash`: whether the decimal point should be written, even if no additional digits are needed for precision
+  * `precision`: minimum number of significant digits to be included in the decimal string; extra `'0'` characters will be added for padding if necessary
+  * `expchar`: character to use exponent component in scientific notation
+  * `padexp`: whether two digits should always be written, even for single-digit exponents (e.g. `e+1` becomes `e+01`)
+  * `decchar`: decimal point character to be used
+"""
+function writeshortest(x::T,
+        plus::Bool=false,
+        space::Bool=false,
+        hash::Bool=true,
+        precision::Integer=-1,
+        expchar::UInt8=UInt8('e'),
+        padexp::Bool=false,
+        decchar::UInt8=UInt8('.')) where {T <: Base.IEEEFloat}
+    buf = Base.StringVector(neededdigits(T))
+    pos = writeshortest(buf, 1, x)
+    @assert pos - 1 <= length(buf)
+    return String(resize!(buf, pos - 1))
+end
+
+"""
+    Ryu.writefixed(x, plus=false, space=false, hash=true, precision=-1, decchar=UInt8('.'))
+    Ryu.writefixed(buf::Vector{UInt8}, pos::Int, x, args...)
+
+Convert a float value `x` into a "fixed" size decimal string.
+This function allows achieving the `%f` printf format.
+Note the 2nd method allows passing in a byte buffer and position directly; callers must ensure the buffer has sufficient room to hold the entire decimal string.
+
+Various options for the output format include:
+  * `plus`: for positive `x`, prefix decimal string with a `'+'` character
+  * `space`: for positive `x`, prefix decimal string with a `' '` character; overridden if `plus=true`
+  * `hash`: whether the decimal point should be written, even if no additional digits are needed for precision
+  * `precision`: minimum number of significant digits to be included in the decimal string; extra `'0'` characters will be added for padding if necessary
+  * `decchar`: decimal point character to be used
+"""
+function writefixed(x::T, precision) where {T <: Base.IEEEFloat}
+    buf = Base.StringVector(precision + neededdigits(T))
+    pos = writefixed(buf, 1, x, false, false, false, precision)
+    @assert pos - 1 <= length(buf)
+    return String(resize!(buf, pos - 1))
+end
+
+"""
+    Ryu.writeexp(x, plus=false, space=false, hash=true, precision=-1, expchar=UInt8('e'), decchar=UInt8('.'))
+    Ryu.writeexp(buf::Vector{UInt8}, pos::Int, x, args...)
+
+Convert a float value `x` into a scientific notation decimal string.
+This function allows achieving the `%e` printf format.
+Note the 2nd method allows passing in a byte buffer and position directly; callers must ensure the buffer has sufficient room to hold the entire decimal string.
+
+Various options for the output format include:
+  * `plus`: for positive `x`, prefix decimal string with a `'+'` character
+  * `space`: for positive `x`, prefix decimal string with a `' '` character; overridden if `plus=true`
+  * `hash`: whether the decimal point should be written, even if no additional digits are needed for precision
+  * `precision`: minimum number of significant digits to be included in the decimal string; extra `'0'` characters will be added for padding if necessary
+  * `expchar`: character to use exponent component in scientific notation
+  * `decchar`: decimal point character to be used
+"""
+function writeexp(x::T, precision) where {T <: Base.IEEEFloat}
+    buf = Base.StringVector(precision + neededdigits(T))
+    pos = writeexp(buf, 1, x, false, false, false, precision)
+    @assert pos - 1 <= length(buf)
+    return String(resize!(buf, pos - 1))
+end
+
+function Base.show(io::IO, x::T) where {T <: Base.IEEEFloat}
+    if get(io, :compact, false)
+        x = round(x, sigdigits=6)
+    end
+    buf = Base.StringVector(neededdigits(T))
+    pos = writeshortest(buf, 1, x)
+    @assert pos - 1 <= length(buf)
+    write(io, resize!(buf, pos - 1))
+    return
+end
+
+end # module