Remove need for readuntil file

base/io.jl

@@ -443,6 +443,90 @@ function readuntil{T}(s::IO, delim::T)
     return out
 end
 
+mutable struct Backtrack{T, C<:AbstractArray}
+    target::Vector{T}
+    pos::Int
+    len::Int
+    cache::C
+    max_pos::Int
+end
+
+function Backtrack(target::AbstractString)
+    t = collect(target)
+    len = length(t)
+    # Setting max_pos to 1 means that backtrack[1] == 0
+    Backtrack(t, 0, len, spzeros(Int, len), 1)
+end
+
+function Backtrack(target::String)
+    t = Vector{UInt8}(target)  # convert String to a utf8-byte-iterator
+    len = length(t)
+    Backtrack(t, 0, len, spzeros(Int, len), 1)
+end
+
+function backtrack(bt::Backtrack, index::Integer)
+    for i = (bt.max_pos + 1):index
+        b = bt.cache[i - 1] + 1
+        # Requires that i > b. We can avoid this check since we start max_pos at 1.
+        if bt.target[i] == bt.target[b]
+            bt.cache[i] = b
+        end
+    end
+    bt.max_pos = index
+    return bt.cache[index]
+end
+
+@inline function record{T}(bt::Backtrack{T}, c::T)
+    i = bt.pos
+    # Backtrack until the next target character matches what was found
+    while i > 0 && c != bt.target[i + 1]
+        i = backtrack(bt, i)
+    end
+    if c == bt.target[i + 1]
+        i += 1
+    end
+    bt.pos = i
+    return i == bt.len
+end
+
+function readuntil(io::IO, target::AbstractString)
+    i = start(target)
+    if done(target, i)
+        return ""
+    end
+    c, i = next(target, i)
+    if done(target, i) && c < Char(0x80)
+        return readuntil_string(s, c % UInt8)
+    end
+    backtrack = Backtrack(target)
+    out = IOBuffer()
+    while !eof(io)
+        c = read(io, Char)
+        write(out, c)
+        record(backtrack, c) && break
+    end
+    return String(take!(out))
+end
+
+function readuntil(s::IO, target::String)
+    i = start(target)
+    if done(target, i)
+        return ""
+    end
+    c, i = next(target, i)
+    if done(target, i) && c < Char(0x80)
+        return readuntil_string(s, c % UInt8)
+    end
+    backtrack = Backtrack(target)
+    out = Base.StringVector(0)
+    while !eof(s)
+        byte = read(s, UInt8)
+        push!(out, byte)
+        record(backtrack, byte) && break
+    end
+    return String(out)
+end
+
 """
     readchomp(x)
 

base/sysimg.jl

@@ -356,7 +356,6 @@ import .Dates: Date, DateTime, DateFormat, @dateformat_str, now
 include("sparse/sparse.jl")
 importall .SparseArrays
 
-include("readuntil.jl")
 include("asyncmap.jl")
 
 include("distributed/Distributed.jl")