countlines now counts final non-empty line even if it doesn't end wit…

…h EOL (JuliaLang#25845)

NEWS.md

@@ -199,6 +199,9 @@ This section lists changes that do not have deprecation warnings.
  * `readuntil` now does *not* include the delimiter in its result, matching the
  behavior of `readline`. Pass `keep=true` to get the old behavior ([#25633]).
 
+ * `countlines` now always counts the last non-empty line even if it does not
+ end with EOL, matching the behavior of `eachline` and `readlines` ([#25845]).
+
  * `getindex(s::String, r::UnitRange{Int})` now throws `UnicodeError` if `last(r)`
  is not a valid index into `s` ([#22572]).
 
@@ -1260,4 +1263,4 @@ Command-line option changes
 [#25622]: https://github.com/JuliaLang/julia/issues/25622
 [#25634]: https://github.com/JuliaLang/julia/issues/25634
 [#25654]: https://github.com/JuliaLang/julia/issues/25654
-[#25655]: https://github.com/JuliaLang/julia/issues/25655
+[#25655]: https://github.com/JuliaLang/julia/issues/25655

base/io.jl

@@ -999,7 +999,8 @@ end
 
 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.
+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
@@ -1011,7 +1012,7 @@ julia> countlines(io)
 julia> io = IOBuffer("JuliaLang is a GitHub organization.");
 
 julia> countlines(io)
-0
+1
 
 julia> countlines(io, eol = '.')
 1
@@ -1021,13 +1022,16 @@ function countlines(io::IO; eol::Char='\n')
  isascii(eol) || throw(ArgumentError("only ASCII line terminators are supported"))
  aeol = UInt8(eol)
  a = Vector{UInt8}(uninitialized, 8192)
- nl = 0
+ 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
 

test/read.jl

@@ -537,15 +537,18 @@ rm(f)
 end # mktempdir() do dir
 
 @testset "countlines" begin
+ @test countlines(IOBuffer("")) == 0
  @test countlines(IOBuffer("\n")) == 1
- @test countlines(IOBuffer("\n"), eol = '\r') == 0
+ @test countlines(IOBuffer("\n"), eol = '\r') == 1
+ @test countlines(IOBuffer("\r\r\n\r"), eol = '\r') == 3
  @test countlines(IOBuffer("\n\n\n\n\n\n\n\n\n\n")) == 10
  @test countlines(IOBuffer("\n \n \n \n \n \n \n \n \n \n")) == 10
  @test countlines(IOBuffer("\r\n \r\n \r\n \r\n \r\n")) == 5
+ @test countlines(IOBuffer("foo\nbar")) == length(readlines(IOBuffer("foo\nbar"))) == 2
  file = tempname()
  write(file,"Spiffy header\nspectacular first row\neven better 2nd row\nalmost done\n")
  @test countlines(file) == 4
- @test countlines(file, eol = '\r') == 0
+ @test countlines(file, eol = '\r') == 1
  @test countlines(file, eol = '\n') == 4
  rm(file)
 end