io.jl
# This file is a part of Julia. License is MIT: https://julialang.org/license
# Generic IO stubs -- all subtypes should implement these (if meaningful)
"""
EOFError()
No more data was available to read from a file or stream.
"""
struct EOFError <: Exception end
"""
SystemError(prefix::AbstractString, [errno::Int32])
A system call failed with an error code (in the `errno` global variable).
"""
struct SystemError <: Exception
prefix::AbstractString
errnum::Int32
extrainfo
SystemError(p::AbstractString, e::Integer, extrainfo) = new(p, e, extrainfo)
SystemError(p::AbstractString, e::Integer) = new(p, e, nothing)
SystemError(p::AbstractString) = new(p, Libc.errno())
end
lock(::IO) = nothing
unlock(::IO) = nothing
reseteof(x::IO) = nothing
const SZ_UNBUFFERED_IO = 65536
buffer_writes(x::IO, bufsize=SZ_UNBUFFERED_IO) = x
"""
isopen(object) -> Bool
Determine whether an object - such as a stream or timer
-- is not yet closed. Once an object is closed, it will never produce a new event.
However, since a closed stream may still have data to read in its buffer,
use [`eof`](@ref) to check for the ability to read data.
Use the `FileWatching` package to be notified when a stream might be writable or readable.
# Examples
```jldoctest
julia> io = open("my_file.txt", "w+");
julia> isopen(io)
true
julia> close(io)
julia> isopen(io)
false
```
"""
function isopen end
"""
close(stream)
Close an I/O stream. Performs a [`flush`](@ref) first.
"""
function close end
function flush end
function wait_connected end
function wait_readnb end
function wait_readbyte end
function wait_close end
function bytesavailable end
"""
readavailable(stream)
Read all available data on the stream, blocking the task only if no data is available. The
result is a `Vector{UInt8,1}`.
"""
function readavailable end
"""
isreadable(io) -> Bool
Return `true` if the specified IO object is readable (if that can be determined).
# Examples
```jldoctest
julia> open("myfile.txt", "w") do io
print(io, "Hello world!");
isreadable(io)
end
false
julia> open("myfile.txt", "r") do io
isreadable(io)
end
true
julia> rm("myfile.txt")
```
"""
function isreadable end
"""
iswritable(io) -> Bool
Return `true` if the specified IO object is writable (if that can be determined).
# Examples
```jldoctest
julia> open("myfile.txt", "w") do io
print(io, "Hello world!");
iswritable(io)
end
true
julia> open("myfile.txt", "r") do io
iswritable(io)
end
false
julia> rm("myfile.txt")
```
"""
function iswritable end
function copy end
function eof end
"""
read(io::IO, T)
Read a single value of type `T` from `io`, in canonical binary representation.
read(io::IO, String)
Read the entirety of `io`, as a `String`.
# Examples
```jldoctest
julia> io = IOBuffer("JuliaLang is a GitHub organization");
julia> read(io, Char)
'J': ASCII/Unicode U+004a (category Lu: Letter, uppercase)
julia> io = IOBuffer("JuliaLang is a GitHub organization");
julia> read(io, String)
"JuliaLang is a GitHub organization"
```
"""
read(stream, t)
"""
write(io::IO, x)
write(filename::AbstractString, x)
Write the canonical binary representation of a value to the given I/O stream or file.
Return the number of bytes written into the stream. See also [`print`](@ref) to
write a text representation (with an encoding that may depend upon `io`).
You can write multiple values with the same `write` call. i.e. the following are equivalent:
write(io, x, y...)
write(io, x) + write(io, y...)
# Examples
```jldoctest
julia> io = IOBuffer();
julia> write(io, "JuliaLang is a GitHub organization.", " It has many members.")
56
julia> String(take!(io))
"JuliaLang is a GitHub organization. It has many members."
julia> write(io, "Sometimes those members") + write(io, " write documentation.")
44
julia> String(take!(io))
"Sometimes those members write documentation."
```
User-defined plain-data types without `write` methods can be written when wrapped in a `Ref`:
```jldoctest
julia> struct MyStruct; x::Float64; end
julia> io = IOBuffer()
IOBuffer(data=UInt8[...], readable=true, writable=true, seekable=true, append=false, size=0, maxsize=Inf, ptr=1, mark=-1)
julia> write(io, Ref(MyStruct(42.0)))
8
julia> seekstart(io); read!(io, Ref(MyStruct(NaN)))
Base.RefValue{MyStruct}(MyStruct(42.0))
```
"""
function write end
read(s::IO, ::Type{UInt8}) = error(typeof(s)," does not support byte I/O")
write(s::IO, x::UInt8) = error(typeof(s)," does not support byte I/O")
"""
unsafe_write(io::IO, ref, nbytes::UInt)
Copy `nbytes` from `ref` (converted to a pointer) into the `IO` object.
It is recommended that subtypes `T<:IO` override the following method signature
to provide more efficient implementations:
`unsafe_write(s::T, p::Ptr{UInt8}, n::UInt)`
"""
function unsafe_write(s::IO, p::Ptr{UInt8}, n::UInt)
written::Int = 0
for i = 1:n
written += write(s, unsafe_load(p, i))
end
return written
end
"""
unsafe_read(io::IO, ref, nbytes::UInt)
Copy `nbytes` from the `IO` stream object into `ref` (converted to a pointer).
It is recommended that subtypes `T<:IO` override the following method signature
to provide more efficient implementations:
`unsafe_read(s::T, p::Ptr{UInt8}, n::UInt)`
"""
function unsafe_read(s::IO, p::Ptr{UInt8}, n::UInt)
for i = 1:n
unsafe_store!(p, read(s, UInt8)::UInt8, i)
end
nothing
end
# Generic wrappers around other IO objects
abstract type AbstractPipe <: IO end
function pipe_reader end
function pipe_writer end
write(io::AbstractPipe, byte::UInt8) = write(pipe_writer(io), byte)
unsafe_write(io::AbstractPipe, p::Ptr{UInt8}, nb::UInt) = unsafe_write(pipe_writer(io), p, nb)
buffer_writes(io::AbstractPipe, args...) = buffer_writes(pipe_writer(io), args...)
flush(io::AbstractPipe) = flush(pipe_writer(io))
read(io::AbstractPipe, byte::Type{UInt8}) = read(pipe_reader(io), byte)
unsafe_read(io::AbstractPipe, p::Ptr{UInt8}, nb::UInt) = unsafe_read(pipe_reader(io), p, nb)
read(io::AbstractPipe) = read(pipe_reader(io))
readuntil(io::AbstractPipe, arg::UInt8; kw...) = readuntil(pipe_reader(io), arg; kw...)
readuntil(io::AbstractPipe, arg::AbstractChar; kw...) = readuntil(pipe_reader(io), arg; kw...)
readuntil(io::AbstractPipe, arg::AbstractString; kw...) = readuntil(pipe_reader(io), arg; kw...)
readuntil(io::AbstractPipe, arg::AbstractVector; kw...) = readuntil(pipe_reader(io), arg; kw...)
readuntil_vector!(io::AbstractPipe, target::AbstractVector, keep::Bool, out) = readuntil_vector!(pipe_reader(io), target, keep, out)
for f in (
# peek/mark interface
:peek, :mark, :unmark, :reset, :ismarked,
# Simple reader functions
:readavailable, :isreadable)
@eval $(f)(io::AbstractPipe) = $(f)(pipe_reader(io))
end
iswritable(io::AbstractPipe) = iswritable(pipe_writer(io))
isopen(io::AbstractPipe) = isopen(pipe_writer(io)) || isopen(pipe_reader(io))
close(io::AbstractPipe) = (close(pipe_writer(io)); close(pipe_reader(io)))
wait_readnb(io::AbstractPipe, nb::Int) = wait_readnb(pipe_reader(io), nb)
wait_readbyte(io::AbstractPipe, byte::UInt8) = wait_readbyte(pipe_reader(io), byte)
wait_close(io::AbstractPipe) = (wait_close(pipe_writer(io)); wait_close(pipe_reader(io)))
"""
bytesavailable(io)
Return the number of bytes available for reading before a read from this stream or buffer will block.
# Examples
```jldoctest
julia> io = IOBuffer("JuliaLang is a GitHub organization");
julia> bytesavailable(io)
34
```
"""
bytesavailable(io::AbstractPipe) = bytesavailable(pipe_reader(io))
"""
eof(stream) -> Bool
Test whether an I/O stream is at end-of-file. If the stream is not yet exhausted, this
function will block to wait for more data if necessary, and then return `false`. Therefore
it is always safe to read one byte after seeing `eof` return `false`. `eof` will return
`false` as long as buffered data is still available, even if the remote end of a connection
is closed.
"""
eof(io::AbstractPipe) = eof(pipe_reader(io))
reseteof(io::AbstractPipe) = reseteof(pipe_reader(io))
# Exception-safe wrappers (io = open(); try f(io) finally close(io))
write(filename::AbstractString, a1, args...) = open(io->write(io, a1, args...), filename, "w")
"""
read(filename::AbstractString, args...)
Open a file and read its contents. `args` is passed to `read`: this is equivalent to
`open(io->read(io, args...), filename)`.
read(filename::AbstractString, String)
Read the entire contents of a file as a string.
"""
read(filename::AbstractString, args...) = open(io->read(io, args...), filename)
read(filename::AbstractString, ::Type{T}) where {T} = open(io->read(io, T), filename)
"""
read!(stream::IO, array::Union{Array, BitArray})
read!(filename::AbstractString, array::Union{Array, BitArray})
Read binary data from an I/O stream or file, filling in `array`.
"""
function read! end
read!(filename::AbstractString, a) = open(io->read!(io, a), filename)
"""
readuntil(stream::IO, delim; keep::Bool = false)
readuntil(filename::AbstractString, delim; keep::Bool = false)
Read a string from an I/O stream or a file, up to the given delimiter.
The delimiter can be a `UInt8`, `AbstractChar`, string, or vector.
Keyword argument `keep` controls whether the delimiter is included in the result.
The text is assumed to be encoded in UTF-8.
# Examples
```jldoctest
julia> open("my_file.txt", "w") do io
write(io, "JuliaLang is a GitHub organization.\\nIt has many members.\\n");
end
57
julia> readuntil("my_file.txt", 'L')
"Julia"
julia> readuntil("my_file.txt", '.', keep = true)
"JuliaLang is a GitHub organization."
julia> rm("my_file.txt")
```
"""
readuntil(filename::AbstractString, args...; kw...) = open(io->readuntil(io, args...; kw...), filename)
"""
readline(io::IO=stdin; keep::Bool=false)
readline(filename::AbstractString; keep::Bool=false)
Read a single line of text from the given I/O stream or file (defaults to `stdin`).
When reading from a file, the text is assumed to be encoded in UTF-8. Lines in the
input end with `'\\n'` or `"\\r\\n"` or the end of an input stream. When `keep` is
false (as it is by default), these trailing newline characters are removed from the
line before it is returned. When `keep` is true, they are returned as part of the
line.
# Examples
```jldoctest
julia> open("my_file.txt", "w") do io
write(io, "JuliaLang is a GitHub organization.\\nIt has many members.\\n");
end
57
julia> readline("my_file.txt")
"JuliaLang is a GitHub organization."
julia> readline("my_file.txt", keep=true)
"JuliaLang is a GitHub organization.\\n"
julia> rm("my_file.txt")
```
"""
function readline(filename::AbstractString; keep::Bool=false)
open(filename) do f
readline(f, keep=keep)
end
end
function readline(s::IO=stdin; keep::Bool=false)::String
line = readuntil(s, 0x0a, keep=true)
i = length(line)
if keep || i == 0 || line[i] != 0x0a
return String(line)
elseif i < 2 || line[i-1] != 0x0d
return String(resize!(line,i-1))
else
return String(resize!(line,i-2))
end
end
"""
readlines(io::IO=stdin; keep::Bool=false)
readlines(filename::AbstractString; keep::Bool=false)
Read all lines of an I/O stream or a file as a vector of strings. Behavior is
equivalent to saving the result of reading [`readline`](@ref) repeatedly with the same
arguments and saving the resulting lines as a vector of strings.
# Examples
```jldoctest
julia> open("my_file.txt", "w") do io
write(io, "JuliaLang is a GitHub organization.\\nIt has many members.\\n");
end
57
julia> readlines("my_file.txt")
2-element Array{String,1}:
"JuliaLang is a GitHub organization."
"It has many members."
julia> readlines("my_file.txt", keep=true)
2-element Array{String,1}:
"JuliaLang is a GitHub organization.\\n"
"It has many members.\\n"
julia> rm("my_file.txt")
```
"""
function readlines(filename::AbstractString; kw...)
open(filename) do f
readlines(f; kw...)
end
end
readlines(s=stdin; kw...) = collect(eachline(s; kw...))
## byte-order mark, ntoh & hton ##
let a = UInt32[0x01020304]
endian_bom = GC.@preserve a unsafe_load(convert(Ptr{UInt8}, pointer(a)))
global ntoh, hton, ltoh, htol
if endian_bom == 0x01
ntoh(x) = x
hton(x) = x
ltoh(x) = bswap(x)
htol(x) = bswap(x)
const global ENDIAN_BOM = 0x01020304
elseif endian_bom == 0x04
ntoh(x) = bswap(x)
hton(x) = bswap(x)
ltoh(x) = x
htol(x) = x
const global ENDIAN_BOM = 0x04030201
else
error("seriously? what is this machine?")
end
end
"""
ENDIAN_BOM
The 32-bit byte-order-mark indicates the native byte order of the host machine.
Little-endian machines will contain the value `0x04030201`. Big-endian machines will contain
the value `0x01020304`.
"""
ENDIAN_BOM
"""
ntoh(x)
Convert the endianness of a value from Network byte order (big-endian) to that used by the Host.
"""
ntoh(x)
"""
hton(x)
Convert the endianness of a value from that used by the Host to Network byte order (big-endian).
"""
hton(x)
"""
ltoh(x)
Convert the endianness of a value from Little-endian to that used by the Host.
"""
ltoh(x)
"""
htol(x)
Convert the endianness of a value from that used by the Host to Little-endian.
"""
htol(x)
"""
isreadonly(io) -> Bool
Determine whether a stream is read-only.
# Examples
```jldoctest
julia> io = IOBuffer("JuliaLang is a GitHub organization");
julia> isreadonly(io)
true
julia> io = IOBuffer();
julia> isreadonly(io)
false
```
"""
isreadonly(s) = isreadable(s) && !iswritable(s)
## binary I/O ##
write(io::IO, x) = throw(MethodError(write, (io, x)))
function write(io::IO, x1, xs...)
written::Int = write(io, x1)
for x in xs
written += write(io, x)
end
return written
end
@noinline unsafe_write(s::IO, p::Ref{T}, n::Integer) where {T} =
unsafe_write(s, unsafe_convert(Ref{T}, p)::Ptr, n) # mark noinline to ensure ref is gc-rooted somewhere (by the caller)
unsafe_write(s::IO, p::Ptr, n::Integer) = unsafe_write(s, convert(Ptr{UInt8}, p), convert(UInt, n))
write(s::IO, x::Ref{T}) where {T} = unsafe_write(s, x, Core.sizeof(T))
write(s::IO, x::Int8) = write(s, reinterpret(UInt8, x))
function write(s::IO, x::Union{Int16,UInt16,Int32,UInt32,Int64,UInt64,Int128,UInt128,Float16,Float32,Float64})
return write(s, Ref(x))
end
write(s::IO, x::Bool) = write(s, UInt8(x))
write(to::IO, p::Ptr) = write(to, convert(UInt, p))
function write(s::IO, A::AbstractArray)
if !isbitstype(eltype(A))
error("`write` is not supported on non-isbits arrays")
end
nb = 0
for a in A
nb += write(s, a)
end
return nb
end
function write(s::IO, a::Array)
if isbitstype(eltype(a))
return GC.@preserve a unsafe_write(s, pointer(a), sizeof(a))
else
error("`write` is not supported on non-isbits arrays")
end
end
function write(s::IO, a::SubArray{T,N,<:Array}) where {T,N}
if !isbitstype(T) || !isa(a, StridedArray)
return invoke(write, Tuple{IO, AbstractArray}, s, a)
end
elsz = sizeof(T)
colsz = size(a,1) * elsz
GC.@preserve a if stride(a,1) != 1
for idxs in CartesianIndices(size(a))
unsafe_write(s, pointer(a, idxs.I), elsz)
end
return elsz * length(a)
elseif N <= 1
return unsafe_write(s, pointer(a, 1), colsz)
else
for idxs in CartesianIndices((1, size(a)[2:end]...))
unsafe_write(s, pointer(a, idxs.I), colsz)
end
return colsz * trailingsize(a,2)
end
end
function write(io::IO, c::Char)
u = bswap(reinterpret(UInt32, c))
n = 1
while true
write(io, u % UInt8)
(u >>= 8) == 0 && return n
n += 1
end
end
# write(io, ::AbstractChar) is not defined: implementations
# must provide their own encoding-specific method.
function write(io::IO, s::Symbol)
pname = unsafe_convert(Ptr{UInt8}, s)
return unsafe_write(io, pname, Int(ccall(:strlen, Csize_t, (Cstring,), pname)))
end
function write(to::IO, from::IO)
n = 0
while !eof(from)
n += write(to, readavailable(from))
end
return n
end
@noinline unsafe_read(s::IO, p::Ref{T}, n::Integer) where {T} = unsafe_read(s, unsafe_convert(Ref{T}, p)::Ptr, n) # mark noinline to ensure ref is gc-rooted somewhere (by the caller)
unsafe_read(s::IO, p::Ptr, n::Integer) = unsafe_read(s, convert(Ptr{UInt8}, p), convert(UInt, n))
read!(s::IO, x::Ref{T}) where {T} = (unsafe_read(s, x, Core.sizeof(T)); x)
read(s::IO, ::Type{Int8}) = reinterpret(Int8, read(s, UInt8))
function read(s::IO, T::Union{Type{Int16},Type{UInt16},Type{Int32},Type{UInt32},Type{Int64},Type{UInt64},Type{Int128},Type{UInt128},Type{Float16},Type{Float32},Type{Float64}})
return read!(s, Ref{T}(0))[]::T
end
read(s::IO, ::Type{Bool}) = (read(s, UInt8) != 0)
read(s::IO, ::Type{Ptr{T}}) where {T} = convert(Ptr{T}, read(s, UInt))
function read!(s::IO, a::Array{UInt8})
GC.@preserve a unsafe_read(s, pointer(a), sizeof(a))
return a
end
function read!(s::IO, a::Array{T}) where T
if isbitstype(T)
GC.@preserve a unsafe_read(s, pointer(a), sizeof(a))
else
for i in eachindex(a)
a[i] = read(s, T)
end
end
return a
end
function read(io::IO, ::Type{Char})
b0 = read(io, UInt8)
l = 8(4-leading_ones(b0))
c = UInt32(b0) << 24
if l < 24
s = 16
while s ≥ l && !eof(io)
peek(io) & 0xc0 == 0x80 || break
b = read(io, UInt8)
c |= UInt32(b) << s
s -= 8
end
end
return reinterpret(Char, c)
end
# read(io, T) is not defined for other AbstractChar: implementations
# must provide their own encoding-specific method.
# readuntil_string is useful below since it has
# an optimized method for s::IOStream
readuntil_string(s::IO, delim::UInt8, keep::Bool) = String(readuntil(s, delim, keep=keep))
function readuntil(s::IO, delim::AbstractChar; keep::Bool=false)
if delim ≤ '\x7f'
return readuntil_string(s, delim % UInt8, keep)
end
out = IOBuffer()
while !eof(s)
c = read(s, Char)
if c == delim
keep && write(out, c)
break
end
write(out, c)
end
return String(take!(out))
end
function readuntil(s::IO, delim::T; keep::Bool=false) where T
out = (T === UInt8 ? StringVector(0) : Vector{T}())
while !eof(s)
c = read(s, T)
if c == delim
keep && push!(out, c)
break
end
push!(out, c)
end
return out
end
# requires that indices for target are the integer unit range from firstindex to lastindex
# returns whether the delimiter was matched
# uses the Knuth–Morris–Pratt_algorithm, with the first and second cache entries unrolled
# For longer targets, the cache improves the big-O efficiency of scanning of sequences
# with repeated patterns
# Each cache entry tells us which index we should start the search at.
# We assume this is unlikely, so we only lazy-initialize as much of the cache as we need to use
# When we allocate the cache, we initialize it to 0 (and offset by the first index afterwards).
# Suppose target is:
# Index: 1245689
# Value: "aδcaδcx"
# We would set the cache to
# 0 0 0 1 2 3 4 0
# So after if we mismatch after the second aδc sequence,
# we can immediately jump back to index 5 (4 + 1).
function readuntil_vector!(io::IO, target::AbstractVector{T}, keep::Bool, out) where {T}
first = firstindex(target)
last = lastindex(target)
len = last - first + 1
if len < 1
return true
end
pos = 0 # array-offset
max_pos = 1 # array-offset in cache
local cache # will be lazy initialized when needed
output! = (isa(out, IO) ? write : push!)
while !eof(io)
c = read(io, T)
# Backtrack until the next target character matches what was found
while true
c1 = target[pos + first]
if c == c1
pos += 1
break
elseif pos == 0
break
elseif pos == 1
if !keep
output!(out, target[first])
end
pos = 0
else
# grow cache to contain up to `pos`
if !@isdefined(cache)
cache = zeros(Int, len)
end
while max_pos < pos
ci = target[max_pos + first]
b = max_pos
max_pos += 1
while b != 0
b = cache[b]
cb = target[b + first]
if ci == cb
cache[max_pos] = b + 1
break
end
end
end
# read new position from cache
pos1 = cache[pos]
if !keep
# and add the removed prefix from the target to the output
# if not always keeping the match
for b in 1:(pos - pos1)
output!(out, target[b - 1 + first])
end
end
pos = pos1
end
end
if keep || pos == 0
output!(out, c)
end
pos == len && return true
end
if !keep
# failed early without finishing the match,
# add the partial match to the output
# if not always keeping the match
for b in 1:pos
output!(out, target[b - 1 + first])
end
end
return false
end
function readuntil(io::IO, target::AbstractString; keep::Bool=false)
# small-string target optimizations
isempty(target) && return ""
c, rest = Iterators.peel(target)
if isempty(rest) && c <= '\x7f'
return readuntil_string(io, c % UInt8, keep)
end
# convert String to a utf8-byte-iterator
if !(target isa String) && !(target isa SubString{String})
target = String(target)
end
target = codeunits(target)::AbstractVector
return String(readuntil(io, target, keep=keep))
end
function readuntil(io::IO, target::AbstractVector{T}; keep::Bool=false) where T
out = (T === UInt8 ? StringVector(0) : Vector{T}())
readuntil_vector!(io, target, keep, out)
return out
end
"""
readchomp(x)
Read the entirety of `x` as a string and remove a single trailing newline
if there is one. Equivalent to `chomp(read(x, String))`.
# Examples
```jldoctest
julia> open("my_file.txt", "w") do io
write(io, "JuliaLang is a GitHub organization.\\nIt has many members.\\n");
end;
julia> readchomp("my_file.txt")
"JuliaLang is a GitHub organization.\\nIt has many members."
julia> rm("my_file.txt");
```
"""
readchomp(x) = chomp(read(x, String))
# read up to nb bytes into nb, returning # bytes read
"""
readbytes!(stream::IO, b::AbstractVector{UInt8}, nb=length(b))
Read at most `nb` bytes from `stream` into `b`, returning the number of bytes read.
The size of `b` will be increased if needed (i.e. if `nb` is greater than `length(b)`
and enough bytes could be read), but it will never be decreased.
"""
function readbytes!(s::IO, b::AbstractArray{UInt8}, nb=length(b))
require_one_based_indexing(b)
olb = lb = length(b)
nr = 0
while nr < nb && !eof(s)
a = read(s, UInt8)
nr += 1
if nr > lb
lb = nr * 2
resize!(b, lb)
end
b[nr] = a
end
if lb > olb
resize!(b, nr) # shrink to just contain input data if was resized
end
return nr
end
"""
read(s::IO, nb=typemax(Int))
Read at most `nb` bytes from `s`, returning a `Vector{UInt8}` of the bytes read.
"""
function read(s::IO, nb::Integer = typemax(Int))
# Let readbytes! grow the array progressively by default
# instead of taking of risk of over-allocating
b = Vector{UInt8}(undef, nb == typemax(Int) ? 1024 : nb)
nr = readbytes!(s, b, nb)
return resize!(b, nr)
end
read(s::IO, ::Type{String}) = String(read(s))
read(s::IO, T::Type) = error("The IO stream does not support reading objects of type $T.")
## high-level iterator interfaces ##
struct EachLine{IOT <: IO}
stream::IOT
ondone::Function
keep::Bool
EachLine(stream::IO=stdin; ondone::Function=()->nothing, keep::Bool=false) =
new{typeof(stream)}(stream, ondone, keep)
end
"""
eachline(io::IO=stdin; keep::Bool=false)
eachline(filename::AbstractString; keep::Bool=false)
Create an iterable `EachLine` object that will yield each line from an I/O stream
or a file. Iteration calls [`readline`](@ref) on the stream argument repeatedly with
`keep` passed through, determining whether trailing end-of-line characters are
retained. When called with a file name, the file is opened once at the beginning of
iteration and closed at the end. If iteration is interrupted, the file will be
closed when the `EachLine` object is garbage collected.
# Examples
```jldoctest
julia> open("my_file.txt", "w") do io
write(io, "JuliaLang is a GitHub organization.\\n It has many members.\\n");
end;
julia> for line in eachline("my_file.txt")
print(line)
end
JuliaLang is a GitHub organization. It has many members.
julia> rm("my_file.txt");
```
"""
function eachline(stream::IO=stdin; keep::Bool=false)
EachLine(stream, keep=keep)::EachLine
end
function eachline(filename::AbstractString; keep::Bool=false)
s = open(filename)
EachLine(s, ondone=()->close(s), keep=keep)::EachLine
end
function iterate(itr::EachLine, state=nothing)
eof(itr.stream) && return (itr.ondone(); nothing)
(readline(itr.stream, keep=itr.keep), nothing)
end
eltype(::Type{<:EachLine}) = String
IteratorSize(::Type{<:EachLine}) = SizeUnknown()
# IOStream Marking
# Note that these functions expect that io.mark exists for
# the concrete IO type. This may not be true for IO types
# not in base.
"""
mark(s)
Add a mark at the current position of stream `s`. Return the marked position.
See also [`unmark`](@ref), [`reset`](@ref), [`ismarked`](@ref).
"""
function mark(io::IO)
io.mark = position(io)
end
"""
unmark(s)
Remove a mark from stream `s`. Return `true` if the stream was marked, `false` otherwise.
See also [`mark`](@ref), [`reset`](@ref), [`ismarked`](@ref).
"""
function unmark(io::IO)
!ismarked(io) && return false
io.mark = -1
return true
end
"""
reset(s)
Reset a stream `s` to a previously marked position, and remove the mark. Return the
previously marked position. Throw an error if the stream is not marked.
See also [`mark`](@ref), [`unmark`](@ref), [`ismarked`](@ref).
"""
function reset(io::T) where T<:IO
ismarked(io) || throw(ArgumentError("$T not marked"))
m = io.mark
seek(io, m)
io.mark = -1 # must be after seek, or seek may fail
return m
end
"""
ismarked(s)
Return `true` if stream `s` is marked.
See also [`mark`](@ref), [`unmark`](@ref), [`reset`](@ref).
"""
ismarked(io::IO) = io.mark >= 0
# Make sure all IO streams support flush, even if only as a no-op,
# to make it easier to write generic I/O code.
"""
flush(stream)
Commit all currently buffered writes to the given stream.
"""
flush(io::IO) = nothing
"""
skipchars(predicate, io::IO; linecomment=nothing)
Advance the stream `io` such that the next-read character will be the first remaining for
which `predicate` returns `false`. If the keyword argument `linecomment` is specified, all
characters from that character until the start of the next line are ignored.
# Examples
```jldoctest
julia> buf = IOBuffer(" text")
IOBuffer(data=UInt8[...], readable=true, writable=false, seekable=true, append=false, size=8, maxsize=Inf, ptr=1, mark=-1)
julia> skipchars(isspace, buf)
IOBuffer(data=UInt8[...], readable=true, writable=false, seekable=true, append=false, size=8, maxsize=Inf, ptr=5, mark=-1)
julia> String(readavailable(buf))
"text"
```
"""
function skipchars(predicate, io::IO; linecomment=nothing)
while !eof(io)
c = read(io, Char)
if c === linecomment
readline(io)
elseif !predicate(c)
skip(io, -ncodeunits(c))
break
end
end
return io
end
"""
countlines(io::IO; eol::AbstractChar = '\\n')
Read `io` until the end of the stream/file and count the number of lines. To specify a file
pass the filename as the first argument. EOL markers other than `'\\n'` are supported by
passing them as the second argument. The last non-empty line of `io` is counted even if it does not
end with the EOL, matching the length returned by [`eachline`](@ref) and [`readlines`](@ref).
# Examples
```jldoctest
julia> io = IOBuffer("JuliaLang is a GitHub organization.\\n");
julia> countlines(io)
1
julia> io = IOBuffer("JuliaLang is a GitHub organization.");
julia> countlines(io)
1
julia> countlines(io, eol = '.')
0
```
"""
function countlines(io::IO; eol::AbstractChar='\n')
isascii(eol) || throw(ArgumentError("only ASCII line terminators are supported"))
aeol = UInt8(eol)
a = Vector{UInt8}(undef, 8192)
nl = nb = 0
while !eof(io)
nb = readbytes!(io, a)
@simd for i=1:nb
@inbounds nl += a[i] == aeol
end
end
if nb > 0 && a[nb] != aeol
nl += 1 # final line is not terminated with eol
end
nl
end
countlines(f::AbstractString; eol::AbstractChar = '\n') = open(io->countlines(io, eol = eol), f)::Int