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util.jl
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# This file is a part of Julia. License is MIT: https://julialang.org/license
const Chars = Union{AbstractChar,Tuple{Vararg{<:AbstractChar}},AbstractVector{<:AbstractChar},Set{<:AbstractChar}}
# starts with and ends with predicates
"""
startswith(s::AbstractString, prefix::AbstractString)
Return `true` if `s` starts with `prefix`. If `prefix` is a vector or set
of characters, test whether the first character of `s` belongs to that set.
See also [`endswith`](@ref).
# Examples
```jldoctest
julia> startswith("JuliaLang", "Julia")
true
```
"""
function startswith(a::AbstractString, b::AbstractString)
a, b = Iterators.Stateful(a), Iterators.Stateful(b)
all(splat(==), zip(a, b)) && isempty(b)
end
startswith(str::AbstractString, chars::Chars) = !isempty(str) && first(str) in chars
"""
endswith(s::AbstractString, suffix::AbstractString)
Return `true` if `s` ends with `suffix`. If `suffix` is a vector or set of
characters, test whether the last character of `s` belongs to that set.
See also [`startswith`](@ref).
# Examples
```jldoctest
julia> endswith("Sunday", "day")
true
```
"""
function endswith(a::AbstractString, b::AbstractString)
a = Iterators.Stateful(Iterators.reverse(a))
b = Iterators.Stateful(Iterators.reverse(b))
all(splat(==), zip(a, b)) && isempty(b)
end
endswith(str::AbstractString, chars::Chars) = !isempty(str) && last(str) in chars
function startswith(a::Union{String, SubString{String}},
b::Union{String, SubString{String}})
cub = ncodeunits(b)
if ncodeunits(a) < cub
false
elseif _memcmp(a, b, sizeof(b)) == 0
nextind(a, cub) == cub + 1
else
false
end
end
function endswith(a::Union{String, SubString{String}},
b::Union{String, SubString{String}})
cub = ncodeunits(b)
astart = ncodeunits(a) - ncodeunits(b) + 1
if astart < 1
false
elseif GC.@preserve(a, _memcmp(pointer(a, astart), b, sizeof(b))) == 0
thisind(a, astart) == astart
else
false
end
end
"""
contains(haystack::AbstractString, needle)
Return `true` if `haystack` contains `needle`.
This is the same as `occursin(needle, haystack)`, but is provided for consistency with
`startswith(haystack, needle)` and `endswith(haystack, needle)`.
# Examples
```jldoctest
julia> contains("JuliaLang is pretty cool!", "Julia")
true
julia> contains("JuliaLang is pretty cool!", 'a')
true
julia> contains("aba", r"a.a")
true
julia> contains("abba", r"a.a")
false
```
!!! compat "Julia 1.5"
The `contains` function requires at least Julia 1.5.
"""
contains(haystack::AbstractString, needle) = occursin(needle, haystack)
"""
endswith(suffix)
Create a function that checks whether its argument ends with `suffix`, i.e.
a function equivalent to `y -> endswith(y, suffix)`.
The returned function is of type `Base.Fix2{typeof(endswith)}`, which can be
used to implement specialized methods.
!!! compat "Julia 1.5"
The single argument `endswith(suffix)` requires at least Julia 1.5.
"""
endswith(s) = Base.Fix2(endswith, s)
"""
startswith(prefix)
Create a function that checks whether its argument starts with `prefix`, i.e.
a function equivalent to `y -> startswith(y, prefix)`.
The returned function is of type `Base.Fix2{typeof(startswith)}`, which can be
used to implement specialized methods.
!!! compat "Julia 1.5"
The single argument `startswith(prefix)` requires at least Julia 1.5.
"""
startswith(s) = Base.Fix2(startswith, s)
"""
contains(needle)
Create a function that checks whether its argument contains `needle`, i.e.
a function equivalent to `haystack -> contains(haystack, needle)`.
The returned function is of type `Base.Fix2{typeof(contains)}`, which can be
used to implement specialized methods.
"""
contains(needle) = Base.Fix2(contains, needle)
"""
chop(s::AbstractString; head::Integer = 0, tail::Integer = 1)
Remove the first `head` and the last `tail` characters from `s`.
The call `chop(s)` removes the last character from `s`.
If it is requested to remove more characters than `length(s)`
then an empty string is returned.
# Examples
```jldoctest
julia> a = "March"
"March"
julia> chop(a)
"Marc"
julia> chop(a, head = 1, tail = 2)
"ar"
julia> chop(a, head = 5, tail = 5)
""
```
"""
function chop(s::AbstractString; head::Integer = 0, tail::Integer = 1)
if isempty(s)
return SubString(s)
end
SubString(s, nextind(s, firstindex(s), head), prevind(s, lastindex(s), tail))
end
# TODO: optimization for the default case based on
# chop(s::AbstractString) = SubString(s, firstindex(s), prevind(s, lastindex(s)))
"""
chomp(s::AbstractString) -> SubString
Remove a single trailing newline from a string.
# Examples
```jldoctest
julia> chomp("Hello\\n")
"Hello"
```
"""
function chomp(s::AbstractString)
i = lastindex(s)
(i < 1 || s[i] != '\n') && (return SubString(s, 1, i))
j = prevind(s,i)
(j < 1 || s[j] != '\r') && (return SubString(s, 1, j))
return SubString(s, 1, prevind(s,j))
end
function chomp(s::String)
i = lastindex(s)
if i < 1 || codeunit(s,i) != 0x0a
return @inbounds SubString(s, 1, i)
elseif i < 2 || codeunit(s,i-1) != 0x0d
return @inbounds SubString(s, 1, prevind(s, i))
else
return @inbounds SubString(s, 1, prevind(s, i-1))
end
end
"""
lstrip([pred=isspace,] str::AbstractString) -> SubString
lstrip(str::AbstractString, chars) -> SubString
Remove leading characters from `str`, either those specified by `chars` or those for
which the function `pred` returns `true`.
The default behaviour is to remove leading whitespace and delimiters: see
[`isspace`](@ref) for precise details.
The optional `chars` argument specifies which characters to remove: it can be a single
character, or a vector or set of characters.
# Examples
```jldoctest
julia> a = lpad("March", 20)
" March"
julia> lstrip(a)
"March"
```
"""
function lstrip(f, s::AbstractString)
e = lastindex(s)
for (i::Int, c::AbstractChar) in pairs(s)
!f(c) && return @inbounds SubString(s, i, e)
end
SubString(s, e+1, e)
end
lstrip(s::AbstractString) = lstrip(isspace, s)
lstrip(s::AbstractString, chars::Chars) = lstrip(in(chars), s)
"""
rstrip([pred=isspace,] str::AbstractString) -> SubString
rstrip(str::AbstractString, chars) -> SubString
Remove trailing characters from `str`, either those specified by `chars` or those for
which the function `pred` returns `true`.
The default behaviour is to remove trailing whitespace and delimiters: see
[`isspace`](@ref) for precise details.
The optional `chars` argument specifies which characters to remove: it can be a single
character, or a vector or set of characters.
# Examples
```jldoctest
julia> a = rpad("March", 20)
"March "
julia> rstrip(a)
"March"
```
"""
function rstrip(f, s::AbstractString)
for (i, c) in Iterators.reverse(pairs(s))
f(c::AbstractChar) || return @inbounds SubString(s, 1, i::Int)
end
SubString(s, 1, 0)
end
rstrip(s::AbstractString) = rstrip(isspace, s)
rstrip(s::AbstractString, chars::Chars) = rstrip(in(chars), s)
"""
strip([pred=isspace,] str::AbstractString) -> SubString
strip(str::AbstractString, chars) -> SubString
Remove leading and trailing characters from `str`, either those specified by `chars` or
those for which the function `pred` returns `true`.
The default behaviour is to remove leading whitespace and delimiters: see
[`isspace`](@ref) for precise details.
The optional `chars` argument specifies which characters to remove: it can be a single
character, vector or set of characters.
!!! compat "Julia 1.2"
The method which accepts a predicate function requires Julia 1.2 or later.
# Examples
```jldoctest
julia> strip("{3, 5}\\n", ['{', '}', '\\n'])
"3, 5"
```
"""
strip(s::AbstractString) = lstrip(rstrip(s))
strip(s::AbstractString, chars::Chars) = lstrip(rstrip(s, chars), chars)
strip(f, s::AbstractString) = lstrip(f, rstrip(f, s))
## string padding functions ##
"""
lpad(s, n::Integer, p::Union{AbstractChar,AbstractString}=' ') -> String
Stringify `s` and pad the resulting string on the left with `p` to make it `n`
characters (code points) long. If `s` is already `n` characters long, an equal
string is returned. Pad with spaces by default.
# Examples
```jldoctest
julia> lpad("March", 10)
" March"
```
"""
lpad(s, n::Integer, p::Union{AbstractChar,AbstractString}=' ') = lpad(string(s), n, string(p))
function lpad(
s::Union{AbstractChar,AbstractString},
n::Integer,
p::Union{AbstractChar,AbstractString}=' ',
) :: String
m = signed(n) - length(s)
m ≤ 0 && return string(s)
l = length(p)
q, r = divrem(m, l)
r == 0 ? string(p^q, s) : string(p^q, first(p, r), s)
end
"""
rpad(s, n::Integer, p::Union{AbstractChar,AbstractString}=' ') -> String
Stringify `s` and pad the resulting string on the right with `p` to make it `n`
characters (code points) long. If `s` is already `n` characters long, an equal
string is returned. Pad with spaces by default.
# Examples
```jldoctest
julia> rpad("March", 20)
"March "
```
"""
rpad(s, n::Integer, p::Union{AbstractChar,AbstractString}=' ') = rpad(string(s), n, string(p))
function rpad(
s::Union{AbstractChar,AbstractString},
n::Integer,
p::Union{AbstractChar,AbstractString}=' ',
) :: String
m = signed(n) - length(s)
m ≤ 0 && return string(s)
l = length(p)
q, r = divrem(m, l)
r == 0 ? string(s, p^q) : string(s, p^q, first(p, r))
end
"""
split(str::AbstractString, dlm; limit::Integer=0, keepempty::Bool=true)
split(str::AbstractString; limit::Integer=0, keepempty::Bool=false)
Split `str` into an array of substrings on occurrences of the delimiter(s) `dlm`. `dlm`
can be any of the formats allowed by [`findnext`](@ref)'s first argument (i.e. as a
string, regular expression or a function), or as a single character or collection of
characters.
If `dlm` is omitted, it defaults to [`isspace`](@ref).
The optional keyword arguments are:
- `limit`: the maximum size of the result. `limit=0` implies no maximum (default)
- `keepempty`: whether empty fields should be kept in the result. Default is `false` without
a `dlm` argument, `true` with a `dlm` argument.
See also [`rsplit`](@ref).
# Examples
```jldoctest
julia> a = "Ma.rch"
"Ma.rch"
julia> split(a, ".")
2-element Vector{SubString{String}}:
"Ma"
"rch"
```
"""
function split end
function split(str::T, splitter;
limit::Integer=0, keepempty::Bool=true) where {T<:AbstractString}
_split(str, splitter, limit, keepempty, T <: SubString ? T[] : SubString{T}[])
end
function split(str::T, splitter::Union{Tuple{Vararg{<:AbstractChar}},AbstractVector{<:AbstractChar},Set{<:AbstractChar}};
limit::Integer=0, keepempty::Bool=true) where {T<:AbstractString}
_split(str, in(splitter), limit, keepempty, T <: SubString ? T[] : SubString{T}[])
end
function split(str::T, splitter::AbstractChar;
limit::Integer=0, keepempty::Bool=true) where {T<:AbstractString}
_split(str, isequal(splitter), limit, keepempty, T <: SubString ? T[] : SubString{T}[])
end
function _split(str::AbstractString, splitter, limit::Integer, keepempty::Bool, strs::Vector)
i = 1 # firstindex(str)
n = lastindex(str)::Int
r = findfirst(splitter,str)::Union{Nothing,Int,UnitRange{Int}}
if !isnothing(r)
j, k = first(r), nextind(str,last(r))::Int
while 0 < j <= n && length(strs) != limit-1
if i < k
if keepempty || i < j
push!(strs, @inbounds SubString(str,i,prevind(str,j)::Int))
end
i = k
end
(k <= j) && (k = nextind(str,j)::Int)
r = findnext(splitter,str,k)::Union{Nothing,Int,UnitRange{Int}}
isnothing(r) && break
j, k = first(r), nextind(str,last(r))::Int
end
end
if keepempty || i <= ncodeunits(str)::Int
push!(strs, @inbounds SubString(str,i))
end
return strs
end
# a bit oddball, but standard behavior in Perl, Ruby & Python:
split(str::AbstractString;
limit::Integer=0, keepempty::Bool=false) =
split(str, isspace; limit=limit, keepempty=keepempty)
"""
rsplit(s::AbstractString; limit::Integer=0, keepempty::Bool=false)
rsplit(s::AbstractString, chars; limit::Integer=0, keepempty::Bool=true)
Similar to [`split`](@ref), but starting from the end of the string.
# Examples
```jldoctest
julia> a = "M.a.r.c.h"
"M.a.r.c.h"
julia> rsplit(a, ".")
5-element Vector{SubString{String}}:
"M"
"a"
"r"
"c"
"h"
julia> rsplit(a, "."; limit=1)
1-element Vector{SubString{String}}:
"M.a.r.c.h"
julia> rsplit(a, "."; limit=2)
2-element Vector{SubString{String}}:
"M.a.r.c"
"h"
```
"""
function rsplit end
function rsplit(str::T, splitter;
limit::Integer=0, keepempty::Bool=true) where {T<:AbstractString}
_rsplit(str, splitter, limit, keepempty, T <: SubString ? T[] : SubString{T}[])
end
function rsplit(str::T, splitter::Union{Tuple{Vararg{<:AbstractChar}},AbstractVector{<:AbstractChar},Set{<:AbstractChar}};
limit::Integer=0, keepempty::Bool=true) where {T<:AbstractString}
_rsplit(str, in(splitter), limit, keepempty, T <: SubString ? T[] : SubString{T}[])
end
function rsplit(str::T, splitter::AbstractChar;
limit::Integer=0, keepempty::Bool=true) where {T<:AbstractString}
_rsplit(str, isequal(splitter), limit, keepempty, T <: SubString ? T[] : SubString{T}[])
end
function _rsplit(str::AbstractString, splitter, limit::Integer, keepempty::Bool, strs::Array)
n = lastindex(str)::Int
r = something(findlast(splitter, str)::Union{Nothing,Int,UnitRange{Int}}, 0)
j, k = first(r), last(r)
while j > 0 && k > 0 && length(strs) != limit-1
(keepempty || k < n) && pushfirst!(strs, @inbounds SubString(str,nextind(str,k)::Int,n))
n = prevind(str, j)::Int
r = something(findprev(splitter,str,n)::Union{Nothing,Int,UnitRange{Int}}, 0)
j, k = first(r), last(r)
end
(keepempty || n > 0) && pushfirst!(strs, SubString(str,1,n))
return strs
end
rsplit(str::AbstractString;
limit::Integer=0, keepempty::Bool=false) =
rsplit(str, isspace; limit=limit, keepempty=keepempty)
_replace(io, repl, str, r, pattern) = print(io, repl)
_replace(io, repl::Function, str, r, pattern) =
print(io, repl(SubString(str, first(r), last(r))))
_replace(io, repl::Function, str, r, pattern::Function) =
print(io, repl(str[first(r)]))
replace(str::String, pat_repl::Pair{<:AbstractChar}; count::Integer=typemax(Int)) =
replace(str, isequal(first(pat_repl)) => last(pat_repl); count=count)
replace(str::String, pat_repl::Pair{<:Union{Tuple{Vararg{<:AbstractChar}},
AbstractVector{<:AbstractChar},Set{<:AbstractChar}}};
count::Integer=typemax(Int)) =
replace(str, in(first(pat_repl)) => last(pat_repl), count=count)
_pat_replacer(x) = x
_free_pat_replacer(x) = nothing
function replace(str::String, pat_repl::Pair; count::Integer=typemax(Int))
pattern, repl = pat_repl
count == 0 && return str
count < 0 && throw(DomainError(count, "`count` must be non-negative."))
n = 1
e = lastindex(str)
i = a = firstindex(str)
pattern = _pat_replacer(pattern)
r = something(findnext(pattern,str,i), 0)
j, k = first(r), last(r)
out = IOBuffer(sizehint=floor(Int, 1.2sizeof(str)))
while j != 0
if i == a || i <= k
GC.@preserve str unsafe_write(out, pointer(str, i), UInt(j-i))
_replace(out, repl, str, r, pattern)
end
if k < j
i = j
j > e && break
k = nextind(str, j)
else
i = k = nextind(str, k)
end
r = something(findnext(pattern,str,k), 0)
r == 0:-1 || n == count && break
j, k = first(r), last(r)
n += 1
end
_free_pat_replacer(pattern)
write(out, SubString(str,i))
String(take!(out))
end
"""
replace(s::AbstractString, pat=>r; [count::Integer])
Search for the given pattern `pat` in `s`, and replace each occurrence with `r`.
If `count` is provided, replace at most `count` occurrences.
`pat` may be a single character, a vector or a set of characters, a string,
or a regular expression.
If `r` is a function, each occurrence is replaced with `r(s)`
where `s` is the matched substring (when `pat` is a `Regex` or `AbstractString`) or
character (when `pat` is an `AbstractChar` or a collection of `AbstractChar`).
If `pat` is a regular expression and `r` is a [`SubstitutionString`](@ref), then capture group
references in `r` are replaced with the corresponding matched text.
To remove instances of `pat` from `string`, set `r` to the empty `String` (`""`).
# Examples
```jldoctest
julia> replace("Python is a programming language.", "Python" => "Julia")
"Julia is a programming language."
julia> replace("The quick foxes run quickly.", "quick" => "slow", count=1)
"The slow foxes run quickly."
julia> replace("The quick foxes run quickly.", "quick" => "", count=1)
"The foxes run quickly."
julia> replace("The quick foxes run quickly.", r"fox(es)?" => s"bus\\1")
"The quick buses run quickly."
```
"""
replace(s::AbstractString, pat_f::Pair; count=typemax(Int)) =
replace(String(s), pat_f, count=count)
# TODO: allow transform as the first argument to replace?
# hex <-> bytes conversion
"""
hex2bytes(s::Union{AbstractString,AbstractVector{UInt8}})
Given a string or array `s` of ASCII codes for a sequence of hexadecimal digits, returns a
`Vector{UInt8}` of bytes corresponding to the binary representation: each successive pair
of hexadecimal digits in `s` gives the value of one byte in the return vector.
The length of `s` must be even, and the returned array has half of the length of `s`.
See also [`hex2bytes!`](@ref) for an in-place version, and [`bytes2hex`](@ref) for the inverse.
# Examples
```jldoctest
julia> s = string(12345, base = 16)
"3039"
julia> hex2bytes(s)
2-element Vector{UInt8}:
0x30
0x39
julia> a = b"01abEF"
6-element Base.CodeUnits{UInt8,String}:
0x30
0x31
0x61
0x62
0x45
0x46
julia> hex2bytes(a)
3-element Vector{UInt8}:
0x01
0xab
0xef
```
"""
function hex2bytes end
hex2bytes(s::AbstractString) = hex2bytes(String(s))
hex2bytes(s::Union{String,AbstractVector{UInt8}}) = hex2bytes!(Vector{UInt8}(undef, length(s) >> 1), s)
_firstbyteidx(s::String) = 1
_firstbyteidx(s::AbstractVector{UInt8}) = first(eachindex(s))
_lastbyteidx(s::String) = sizeof(s)
_lastbyteidx(s::AbstractVector{UInt8}) = lastindex(s)
"""
hex2bytes!(d::AbstractVector{UInt8}, s::Union{String,AbstractVector{UInt8}})
Convert an array `s` of bytes representing a hexadecimal string to its binary
representation, similar to [`hex2bytes`](@ref) except that the output is written in-place
in `d`. The length of `s` must be exactly twice the length of `d`.
"""
function hex2bytes!(d::AbstractVector{UInt8}, s::Union{String,AbstractVector{UInt8}})
if 2length(d) != sizeof(s)
isodd(sizeof(s)) && throw(ArgumentError("input hex array must have even length"))
throw(ArgumentError("output array must be half length of input array"))
end
j = first(eachindex(d)) - 1
for i = _firstbyteidx(s):2:_lastbyteidx(s)
@inbounds d[j += 1] = number_from_hex(_nthbyte(s,i)) << 4 + number_from_hex(_nthbyte(s,i+1))
end
return d
end
@inline number_from_hex(c) =
(UInt8('0') <= c <= UInt8('9')) ? c - UInt8('0') :
(UInt8('A') <= c <= UInt8('F')) ? c - (UInt8('A') - 0x0a) :
(UInt8('a') <= c <= UInt8('f')) ? c - (UInt8('a') - 0x0a) :
throw(ArgumentError("byte is not an ASCII hexadecimal digit"))
"""
bytes2hex(a::AbstractArray{UInt8}) -> String
bytes2hex(io::IO, a::AbstractArray{UInt8})
Convert an array `a` of bytes to its hexadecimal string representation, either
returning a `String` via `bytes2hex(a)` or writing the string to an `io` stream
via `bytes2hex(io, a)`. The hexadecimal characters are all lowercase.
# Examples
```jldoctest
julia> a = string(12345, base = 16)
"3039"
julia> b = hex2bytes(a)
2-element Vector{UInt8}:
0x30
0x39
julia> bytes2hex(b)
"3039"
```
"""
function bytes2hex end
function bytes2hex(a::AbstractArray{UInt8})
b = Base.StringVector(2*length(a))
@inbounds for (i, x) in enumerate(a)
b[2i - 1] = hex_chars[1 + x >> 4]
b[2i ] = hex_chars[1 + x & 0xf]
end
return String(b)
end
bytes2hex(io::IO, a::AbstractArray{UInt8}) =
for x in a
print(io, Char(hex_chars[1 + x >> 4]), Char(hex_chars[1 + x & 0xf]))
end
# check for pure ASCII-ness
function ascii(s::String)
for i in 1:sizeof(s)
@inbounds codeunit(s, i) < 0x80 || __throw_invalid_ascii(s, i)
end
return s
end
@noinline __throw_invalid_ascii(s::String, i::Int) = throw(ArgumentError("invalid ASCII at index $i in $(repr(s))"))
"""
ascii(s::AbstractString)
Convert a string to `String` type and check that it contains only ASCII data, otherwise
throwing an `ArgumentError` indicating the position of the first non-ASCII byte.
# Examples
```jldoctest
julia> ascii("abcdeγfgh")
ERROR: ArgumentError: invalid ASCII at index 6 in "abcdeγfgh"
Stacktrace:
[...]
julia> ascii("abcdefgh")
"abcdefgh"
```
"""
ascii(x::AbstractString) = ascii(String(x))