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omusomus
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Merge pull request #1 from JuliaMath/cv/parse
Add support for creating FixedDecimals from strings
2 parents 9627c91 + 0ebb0ce commit 4dd5492

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2 files changed

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‎src/FixedPointDecimals.jl

Lines changed: 73 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -25,13 +25,13 @@ __precompile__()
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module FixedPointDecimals
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export FixedDecimal
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export FixedDecimal, RoundThrows
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using Compat
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import Base: reinterpret, zero, one, abs, sign, ==, <, <=, +, -, /, *, div,
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rem, divrem, fld, mod, fldmod, fld1, mod1, fldmod1, isinteger,
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typemin, typemax, realmin, realmax, print, show, string, convert,
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typemin, typemax, realmin, realmax, print, show, string, convert, parse,
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promote_rule, min, max, trunc, round, floor, ceil, eps, float, widemul
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import Base.Checked: checked_mul
@@ -311,4 +311,75 @@ function show{T, f}(io::IO, x::FD{T, f})
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end
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end
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# parsing
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"""
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RoundThrows
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Raises an `InexactError` if any rounding is necessary.
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"""
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const RoundThrows = RoundingMode{:Throw}()
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function parse{T, f}(::Type{FD{T, f}}, str::AbstractString, mode::RoundingMode=RoundNearest)
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if !(mode in [RoundThrows, RoundNearest, RoundToZero])
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throw(ArgumentError("Unhandled rounding mode $mode"))
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end
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# Parse exponent information
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exp_index = findfirst(str, 'e')
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if exp_index > 0
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exp = parse(Int, str[(exp_index + 1):end])
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sig_end = exp_index - 1
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else
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exp = 0
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sig_end = endof(str)
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end
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# Remove the decimal place from the string
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sign = T(first(str) == '-' ? -1 : 1)
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dec_index = findfirst(str, '.')
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sig_start = sign < 0 ? 2 : 1
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if dec_index > 0
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int_str = str[sig_start:(dec_index - 1)] * str[(dec_index + 1):sig_end]
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exp -= sig_end - dec_index
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else
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int_str = str[sig_start:sig_end]
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end
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# Split the integer string into the value we can represent inside the FixedDecimal and
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# the remaining digits we'll use during rounding
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int_end = endof(int_str)
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pivot = int_end + exp - (-f)
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a = rpad(int_str[1:min(pivot, int_end)], pivot, '0')
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b = lpad(int_str[max(pivot, 1):int_end], int_end - pivot + 1, '0')
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# Parse the strings
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val = isempty(a) ? T(0) : sign * parse(T, a)
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if !isempty(b) && any(collect(b[2:end]) .!= '0')
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if mode == RoundThrows
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throw(InexactError())
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elseif mode == RoundNearest
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val += sign * parse_round(T, b, mode)
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end
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end
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reinterpret(FD{T, f}, val)
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end
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function parse_round{T}(::Type{T}, fractional::AbstractString, ::RoundingMode{:Nearest})
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# Note: parsing each digit individually ensures we don't run into an OverflowError
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digits = Int8[parse(Int8, d) for d in fractional]
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for i in length(digits):-1:2
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if digits[i] > 5 || digits[i] == 5 && isodd(digits[i - 1])
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if i - 1 == 1
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return T(1)
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else
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digits[i - 1] += 1
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end
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end
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end
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return T(0)
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end
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end

‎test/runtests.jl

Lines changed: 140 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -454,4 +454,144 @@ end
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end
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end
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@testset "parse_round" begin
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@test FixedPointDecimals.parse_round(Int, "44", RoundNearest) == 0
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@test FixedPointDecimals.parse_round(Int, "45", RoundNearest) == 0
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@test FixedPointDecimals.parse_round(Int, "46", RoundNearest) == 1
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@test FixedPointDecimals.parse_round(Int, "54", RoundNearest) == 0
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@test FixedPointDecimals.parse_round(Int, "55", RoundNearest) == 1
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@test FixedPointDecimals.parse_round(Int, "56", RoundNearest) == 1
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# Handle a number of digits that exceeds the storage capacity of Int128
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@test FixedPointDecimals.parse_round(Int8, "9"^40, RoundNearest) == 1
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end
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@testset "parse" begin
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# Note: the underscore used in the reinterpreted integer is used to indicate the decimal
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# place.
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@testset "decimal position" begin
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@test parse(FD2, "123") == reinterpret(FD2, 123_00)
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@test parse(FD2, "0.123") == reinterpret(FD2, 0_12)
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@test parse(FD2, ".123") == reinterpret(FD2, 0_12)
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@test parse(FD2, "1.23") == reinterpret(FD2, 1_23)
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@test parse(FD2, "12.3") == reinterpret(FD2, 12_30)
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@test parse(FD2, "123.") == reinterpret(FD2, 123_00)
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@test parse(FD2, "123.0") == reinterpret(FD2, 123_00)
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@test parse(FD2, "-123") == reinterpret(FD2, -123_00)
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@test parse(FD2, "-0.123") == reinterpret(FD2, -0_12)
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@test parse(FD2, "-.123") == reinterpret(FD2, -0_12)
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@test parse(FD2, "-1.23") == reinterpret(FD2, -1_23)
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@test parse(FD2, "-12.3") == reinterpret(FD2, -12_30)
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@test parse(FD2, "-123.") == reinterpret(FD2, -123_00)
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@test parse(FD2, "-123.0") == reinterpret(FD2, -123_00)
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end
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@testset "scientific notation" begin
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@test parse(FD4, "12e0") == reinterpret(FD4, 00012_0000)
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@test parse(FD4, "12e3") == reinterpret(FD4, 12000_0000)
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@test parse(FD4, "12e-3") == reinterpret(FD4, 00000_0120)
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@test parse(FD4, "1.2e0") == reinterpret(FD4, 00001_2000)
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@test parse(FD4, "1.2e3") == reinterpret(FD4, 01200_0000)
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@test parse(FD4, "1.2e-3") == reinterpret(FD4, 00000_0012)
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@test parse(FD4, "1.2e-4") == reinterpret(FD4, 00000_0001)
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@test parse(FD4, "-12e0") == reinterpret(FD4, -00012_0000)
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@test parse(FD4, "-12e3") == reinterpret(FD4, -12000_0000)
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@test parse(FD4, "-12e-3") == reinterpret(FD4, -00000_0120)
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@test parse(FD4, "-1.2e0") == reinterpret(FD4, -00001_2000)
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@test parse(FD4, "-1.2e3") == reinterpret(FD4, -01200_0000)
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@test parse(FD4, "-1.2e-3") == reinterpret(FD4, -00000_0012)
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@test parse(FD2, "999e-1") == reinterpret(FD2, 99_90)
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@test parse(FD2, "999e-2") == reinterpret(FD2, 09_99)
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@test parse(FD2, "999e-3") == reinterpret(FD2, 01_00)
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@test parse(FD2, "999e-4") == reinterpret(FD2, 00_10)
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@test parse(FD2, "999e-5") == reinterpret(FD2, 00_01)
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@test parse(FD2, "999e-6") == reinterpret(FD2, 00_00)
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@test parse(FD2, "-999e-1") == reinterpret(FD2, -99_90)
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@test parse(FD2, "-999e-2") == reinterpret(FD2, -09_99)
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@test parse(FD2, "-999e-3") == reinterpret(FD2, -01_00)
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@test parse(FD2, "-999e-4") == reinterpret(FD2, -00_10)
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@test parse(FD2, "-999e-5") == reinterpret(FD2, -00_01)
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@test parse(FD2, "-999e-6") == reinterpret(FD2, -00_00)
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@test parse(FD4, "9"^96 * "e-100") == reinterpret(FD4, 0_001)
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end
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@testset "round to nearest" begin
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@test parse(FD2, "0.444") == reinterpret(FD2, 0_44)
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@test parse(FD2, "0.445") == reinterpret(FD2, 0_44)
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@test parse(FD2, "0.446") == reinterpret(FD2, 0_45)
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@test parse(FD2, "0.454") == reinterpret(FD2, 0_45)
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@test parse(FD2, "0.455") == reinterpret(FD2, 0_46)
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@test parse(FD2, "0.456") == reinterpret(FD2, 0_46)
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@test parse(FD2, "-0.444") == reinterpret(FD2, -0_44)
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@test parse(FD2, "-0.445") == reinterpret(FD2, -0_44)
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@test parse(FD2, "-0.446") == reinterpret(FD2, -0_45)
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@test parse(FD2, "-0.454") == reinterpret(FD2, -0_45)
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@test parse(FD2, "-0.455") == reinterpret(FD2, -0_46)
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@test parse(FD2, "-0.456") == reinterpret(FD2, -0_46)
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@test parse(FD2, "0.009") == reinterpret(FD2, 0_01)
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@test parse(FD2, "-0.009") == reinterpret(FD2, -0_01)
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@test parse(FD4, "1.5e-4") == reinterpret(FD4, 0_0002)
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end
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@testset "round to zero" begin
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@test parse(FD2, "0.444", RoundToZero) == reinterpret(FD2, 0_44)
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@test parse(FD2, "0.445", RoundToZero) == reinterpret(FD2, 0_44)
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@test parse(FD2, "0.446", RoundToZero) == reinterpret(FD2, 0_44)
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@test parse(FD2, "0.454", RoundToZero) == reinterpret(FD2, 0_45)
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@test parse(FD2, "0.455", RoundToZero) == reinterpret(FD2, 0_45)
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@test parse(FD2, "0.456", RoundToZero) == reinterpret(FD2, 0_45)
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@test parse(FD2, "-0.444", RoundToZero) == reinterpret(FD2, -0_44)
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@test parse(FD2, "-0.445", RoundToZero) == reinterpret(FD2, -0_44)
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@test parse(FD2, "-0.446", RoundToZero) == reinterpret(FD2, -0_44)
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@test parse(FD2, "-0.454", RoundToZero) == reinterpret(FD2, -0_45)
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@test parse(FD2, "-0.455", RoundToZero) == reinterpret(FD2, -0_45)
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@test parse(FD2, "-0.456", RoundToZero) == reinterpret(FD2, -0_45)
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@test parse(FD2, "0.009", RoundToZero) == reinterpret(FD2, 0_00)
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@test parse(FD2, "-0.009", RoundToZero) == reinterpret(FD2, 0_00)
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@test parse(FD4, "1.5e-4", RoundToZero) == reinterpret(FD4, 0_0001)
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end
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@testset "round throws" begin
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@test parse(FD2, "0.44", RoundThrows) == reinterpret(FD2, 0_44)
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@test parse(FD2, "0.440", RoundThrows) == reinterpret(FD2, 0_44)
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@test_throws InexactError parse(FD2, "0.444", RoundThrows)
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@test_throws InexactError parse(FD2, "0.445", RoundThrows)
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@test_throws InexactError parse(FD2, "0.446", RoundThrows)
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@test_throws InexactError parse(FD2, "0.454", RoundThrows)
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@test_throws InexactError parse(FD2, "0.455", RoundThrows)
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@test_throws InexactError parse(FD2, "0.456", RoundThrows)
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@test_throws InexactError parse(FD2, "-0.444", RoundThrows)
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@test_throws InexactError parse(FD2, "-0.445", RoundThrows)
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@test_throws InexactError parse(FD2, "-0.446", RoundThrows)
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@test_throws InexactError parse(FD2, "-0.454", RoundThrows)
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@test_throws InexactError parse(FD2, "-0.455", RoundThrows)
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@test_throws InexactError parse(FD2, "-0.456", RoundThrows)
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@test_throws InexactError parse(FD2, "0.009", RoundThrows)
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@test_throws InexactError parse(FD2, "-0.009", RoundThrows)
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@test_throws InexactError parse(FD4, "1.5e-4", RoundThrows)
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end
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@testset "invalid" begin
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@test_throws OverflowError parse(FD4, "1.2e100")
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@test_throws ArgumentError parse(FD4, "foo")
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@test_throws ArgumentError parse(FD4, "1.2.3")
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@test_throws ArgumentError parse(FD4, "1.2", RoundUp)
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end
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end
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end # global testset

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