Revision 41697f9d282e991562c166ecc362922a8cb8fb84 authored by Jeff Bezanson on 02 November 2017, 21:59:43 UTC, committed by Jeff Bezanson on 29 December 2017, 20:45:37 UTC
1 parent 2a56a37
parse.jl
# This file is a part of Julia. License is MIT: https://julialang.org/license
import Base.Checked: add_with_overflow, mul_with_overflow
## string to integer functions ##
"""
parse(type, str, [base])
Parse a string as a number. For `Integer` types, a base can be specified
(the default is 10). For floating-point types, the string is parsed as a decimal
floating-point number. `Complex` types are parsed from decimal strings
of the form `"R±Iim"` as a `Complex(R,I)` of the requested type; `"i"` or `"j"` can also be
used instead of `"im"`, and `"R"` or `"Iim"` are also permitted.
If the string does not contain a valid number, an error is raised.
```jldoctest
julia> parse(Int, "1234")
1234
julia> parse(Int, "1234", 5)
194
julia> parse(Int, "afc", 16)
2812
julia> parse(Float64, "1.2e-3")
0.0012
julia> parse(Complex{Float64}, "3.2e-1 + 4.5im")
0.32 + 4.5im
```
"""
parse(T::Type, str, base=Int)
function parse(::Type{T}, c::Char, base::Integer=36) where T<:Integer
a::Int = (base <= 36 ? 10 : 36)
2 <= base <= 62 || throw(ArgumentError("invalid base: base must be 2 ≤ base ≤ 62, got $base"))
d = '0' <= c <= '9' ? c-'0' :
'A' <= c <= 'Z' ? c-'A'+10 :
'a' <= c <= 'z' ? c-'a'+a : throw(ArgumentError("invalid digit: $(repr(c))"))
d < base || throw(ArgumentError("invalid base $base digit $(repr(c))"))
convert(T, d)
end
function parseint_next(s::AbstractString, startpos::Int, endpos::Int)
(0 < startpos <= endpos) || (return Char(0), 0, 0)
j = startpos
c, startpos = next(s,startpos)
c, startpos, j
end
function parseint_preamble(signed::Bool, base::Int, s::AbstractString, startpos::Int, endpos::Int)
c, i, j = parseint_next(s, startpos, endpos)
while Unicode.isspace(c)
c, i, j = parseint_next(s,i,endpos)
end
(j == 0) && (return 0, 0, 0)
sgn = 1
if signed
if c == '-' || c == '+'
(c == '-') && (sgn = -1)
c, i, j = parseint_next(s,i,endpos)
end
end
while Unicode.isspace(c)
c, i, j = parseint_next(s,i,endpos)
end
(j == 0) && (return 0, 0, 0)
if base == 0
if c == '0' && !done(s,i)
c, i = next(s,i)
base = c=='b' ? 2 : c=='o' ? 8 : c=='x' ? 16 : 10
if base != 10
c, i, j = parseint_next(s,i,endpos)
end
else
base = 10
end
end
return sgn, base, j
end
function tryparse_internal(::Type{T}, s::AbstractString, startpos::Int, endpos::Int, base_::Integer, raise::Bool) where T<:Integer
sgn, base, i = parseint_preamble(T<:Signed, Int(base_), s, startpos, endpos)
if sgn == 0 && base == 0 && i == 0
raise && throw(ArgumentError("input string is empty or only contains whitespace"))
return nothing
end
if !(2 <= base <= 62)
raise && throw(ArgumentError("invalid base: base must be 2 ≤ base ≤ 62, got $base"))
return nothing
end
if i == 0
raise && throw(ArgumentError("premature end of integer: $(repr(SubString(s,startpos,endpos)))"))
return nothing
end
c, i = parseint_next(s,i,endpos)
if i == 0
raise && throw(ArgumentError("premature end of integer: $(repr(SubString(s,startpos,endpos)))"))
return nothing
end
base = convert(T,base)
m::T = div(typemax(T)-base+1,base)
n::T = 0
a::Int = base <= 36 ? 10 : 36
while n <= m
d::T = '0' <= c <= '9' ? c-'0' :
'A' <= c <= 'Z' ? c-'A'+10 :
'a' <= c <= 'z' ? c-'a'+a : base
if d >= base
raise && throw(ArgumentError("invalid base $base digit $(repr(c)) in $(repr(SubString(s,startpos,endpos)))"))
return nothing
end
n *= base
n += d
if i > endpos
n *= sgn
return n
end
c, i = next(s,i)
Unicode.isspace(c) && break
end
(T <: Signed) && (n *= sgn)
while !Unicode.isspace(c)
d::T = '0' <= c <= '9' ? c-'0' :
'A' <= c <= 'Z' ? c-'A'+10 :
'a' <= c <= 'z' ? c-'a'+a : base
if d >= base
raise && throw(ArgumentError("invalid base $base digit $(repr(c)) in $(repr(SubString(s,startpos,endpos)))"))
return nothing
end
(T <: Signed) && (d *= sgn)
n, ov_mul = mul_with_overflow(n, base)
n, ov_add = add_with_overflow(n, d)
if ov_mul | ov_add
raise && throw(OverflowError("overflow parsing $(repr(SubString(s,startpos,endpos)))"))
return nothing
end
(i > endpos) && return n
c, i = next(s,i)
end
while i <= endpos
c, i = next(s,i)
if !Unicode.isspace(c)
raise && throw(ArgumentError("extra characters after whitespace in $(repr(SubString(s,startpos,endpos)))"))
return nothing
end
end
return n
end
function tryparse_internal(::Type{Bool}, sbuff::Union{String,SubString{String}},
startpos::Int, endpos::Int, base::Integer, raise::Bool)
if isempty(sbuff)
raise && throw(ArgumentError("input string is empty"))
return nothing
end
orig_start = startpos
orig_end = endpos
# Ignore leading and trailing whitespace
while Unicode.isspace(sbuff[startpos]) && startpos <= endpos
startpos = nextind(sbuff, startpos)
end
while Unicode.isspace(sbuff[endpos]) && endpos >= startpos
endpos = prevind(sbuff, endpos)
end
len = endpos - startpos + 1
p = pointer(sbuff) + startpos - 1
@gc_preserve sbuff begin
(len == 4) && (0 == ccall(:memcmp, Int32, (Ptr{UInt8}, Ptr{UInt8}, UInt),
p, "true", 4)) && (return true)
(len == 5) && (0 == ccall(:memcmp, Int32, (Ptr{UInt8}, Ptr{UInt8}, UInt),
p, "false", 5)) && (return false)
end
if raise
substr = SubString(sbuff, orig_start, orig_end) # show input string in the error to avoid confusion
if all(Unicode.isspace, substr)
throw(ArgumentError("input string only contains whitespace"))
else
throw(ArgumentError("invalid Bool representation: $(repr(substr))"))
end
end
return nothing
end
@inline function check_valid_base(base)
if 2 <= base <= 62
return base
end
throw(ArgumentError("invalid base: base must be 2 ≤ base ≤ 62, got $base"))
end
"""
tryparse(type, str, [base])
Like [`parse`](@ref), but returns either a value of the requested type,
or [`nothing`](@ref) if the string does not contain a valid number.
"""
tryparse(::Type{T}, s::AbstractString, base::Integer) where {T<:Integer} =
tryparse_internal(T, s, start(s), endof(s), check_valid_base(base), false)
tryparse(::Type{T}, s::AbstractString) where {T<:Integer} =
tryparse_internal(T, s, start(s), endof(s), 0, false)
function parse(::Type{T}, s::AbstractString, base::Integer) where T<:Integer
tryparse_internal(T, s, start(s), endof(s), check_valid_base(base), true)
end
function parse(::Type{T}, s::AbstractString) where T<:Integer
tryparse_internal(T, s, start(s), endof(s), 0, true) # Zero means, "figure it out"
end
## string to float functions ##
function tryparse(::Type{Float64}, s::String)
hasvalue, val = ccall(:jl_try_substrtod, Tuple{Bool, Float64},
(Ptr{UInt8},Csize_t,Csize_t), s, 0, sizeof(s))
hasvalue ? val : nothing
end
function tryparse(::Type{Float64}, s::SubString{String})
hasvalue, val = ccall(:jl_try_substrtod, Tuple{Bool, Float64},
(Ptr{UInt8},Csize_t,Csize_t), s.string, s.offset, s.ncodeunits)
hasvalue ? val : nothing
end
function tryparse_internal(::Type{Float64}, s::String, startpos::Int, endpos::Int)
hasvalue, val = ccall(:jl_try_substrtod, Tuple{Bool, Float64},
(Ptr{UInt8},Csize_t,Csize_t), s, startpos-1, endpos-startpos+1)
hasvalue ? val : nothing
end
function tryparse_internal(::Type{Float64}, s::SubString{String}, startpos::Int, endpos::Int)
hasvalue, val = ccall(:jl_try_substrtod, Tuple{Bool, Float64},
(Ptr{UInt8},Csize_t,Csize_t), s.string, s.offset+startpos-1, endpos-startpos+1)
hasvalue ? val : nothing
end
function tryparse(::Type{Float32}, s::String)
hasvalue, val = ccall(:jl_try_substrtof, Tuple{Bool, Float32},
(Ptr{UInt8},Csize_t,Csize_t), s, 0, sizeof(s))
hasvalue ? val : nothing
end
function tryparse(::Type{Float32}, s::SubString{String})
hasvalue, val = ccall(:jl_try_substrtof, Tuple{Bool, Float32},
(Ptr{UInt8},Csize_t,Csize_t), s.string, s.offset, s.ncodeunits)
hasvalue ? val : nothing
end
function tryparse_internal(::Type{Float32}, s::String, startpos::Int, endpos::Int)
hasvalue, val = ccall(:jl_try_substrtof, Tuple{Bool, Float32},
(Ptr{UInt8},Csize_t,Csize_t), s, startpos-1, endpos-startpos+1)
hasvalue ? val : nothing
end
function tryparse_internal(::Type{Float32}, s::SubString{String}, startpos::Int, endpos::Int)
hasvalue, val = ccall(:jl_try_substrtof, Tuple{Bool, Float32},
(Ptr{UInt8},Csize_t,Csize_t), s.string, s.offset+startpos-1, endpos-startpos+1)
hasvalue ? val : nothing
end
tryparse(::Type{T}, s::AbstractString) where {T<:Union{Float32,Float64}} = tryparse(T, String(s))
tryparse(::Type{Float16}, s::AbstractString) =
convert(Union{Float16, Nothing}, tryparse(Float32, s))
tryparse_internal(::Type{Float16}, s::AbstractString, startpos::Int, endpos::Int) =
convert(Union{Float16, Nothing}, tryparse_internal(Float32, s, startpos, endpos))
## string to complex functions ##
function tryparse_internal(::Type{Complex{T}}, s::Union{String,SubString{String}}, i::Int, e::Int, raise::Bool) where {T<:Real}
# skip initial whitespace
while i ≤ e && Unicode.isspace(s[i])
i = nextind(s, i)
end
if i > e
raise && throw(ArgumentError("input string is empty or only contains whitespace"))
return nothing
end
# find index of ± separating real/imaginary parts (if any)
i₊ = search(s, ('+','-'), i)
if i₊ == i # leading ± sign
i₊ = search(s, ('+','-'), i₊+1)
end
if i₊ != 0 && s[i₊-1] in ('e','E') # exponent sign
i₊ = search(s, ('+','-'), i₊+1)
end
# find trailing im/i/j
iᵢ = rsearch(s, ('m','i','j'), e)
if iᵢ > 0 && s[iᵢ] == 'm' # im
iᵢ -= 1
if s[iᵢ] != 'i'
raise && throw(ArgumentError("expected trailing \"im\", found only \"m\""))
return nothing
end
end
if i₊ == 0 # purely real or imaginary value
if iᵢ > 0 # purely imaginary
x = tryparse_internal(T, s, i, iᵢ-1, raise)
x === nothing && return nothing
return Complex{T}(zero(x),x)
else # purely real
return Complex{T}(tryparse_internal(T, s, i, e, raise))
end
end
if iᵢ < i₊
raise && throw(ArgumentError("missing imaginary unit"))
return nothing # no imaginary part
end
# parse real part
re = tryparse_internal(T, s, i, i₊-1, raise)
re === nothing && return nothing
# parse imaginary part
im = tryparse_internal(T, s, i₊+1, iᵢ-1, raise)
im === nothing && return nothing
return Complex{T}(re, s[i₊]=='-' ? -im : im)
end
# the ±1 indexing above for ascii chars is specific to String, so convert:
tryparse_internal(T::Type{<:Complex}, s::AbstractString, i::Int, e::Int, raise::Bool) =
tryparse_internal(T, String(s), i, e, raise)
# fallback methods for tryparse_internal
tryparse_internal(::Type{T}, s::AbstractString, startpos::Int, endpos::Int) where T<:Real =
startpos == start(s) && endpos == endof(s) ? tryparse(T, s) : tryparse(T, SubString(s, startpos, endpos))
function tryparse_internal(::Type{T}, s::AbstractString, startpos::Int, endpos::Int, raise::Bool) where T<:Real
result = tryparse_internal(T, s, startpos, endpos)
if raise && result === nothing
throw(ArgumentError("cannot parse $(repr(s[startpos:endpos])) as $T"))
end
return result
end
tryparse_internal(::Type{T}, s::AbstractString, startpos::Int, endpos::Int, raise::Bool) where T<:Integer =
tryparse_internal(T, s, startpos, endpos, 10, raise)
parse(::Type{T}, s::AbstractString) where T<:Union{Real,Complex} =
tryparse_internal(T, s, start(s), endof(s), true)
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