Add Compat.StringVector (#348)

* Add Compat.StringVector

README.md

@@ -163,6 +163,8 @@ Currently, the `@compat` macro supports the following syntaxes:
 
 * `bswap` is supported for `Complex` arguments on 0.5 and below. ([#21346])
 
+* `Compat.StringVector` is supported on 0.5 and below. On 0.6 and later, it aliases `Base.StringVector`. This function allocates a `Vector{UInt8}` whose data can be made into a `String` in constant time; that is, without copying. On 0.5 and later, use `String(...)` with the vector allocated by `StringVector` as an argument to create a string without copying. Note that if 0.4 support is needed, `Compat.UTF8String(...)` should be used instead. ([#19449])
+
 ## Renamed functions
 
 * `pointer_to_array` and `pointer_to_string` have been replaced with `unsafe_wrap(Array, ...)` and `unsafe_wrap(String, ...)` respectively

src/Compat.jl

@@ -1464,6 +1464,13 @@ if VERSION < v"0.6.0-pre.beta.102"
     Base.bswap(z::Complex) = Complex(bswap(real(z)), bswap(imag(z)))
 end
 
+# https://github.com/JuliaLang/julia/pull/19449
+if VERSION < v"0.6.0-dev.1988"
+    StringVector(n::Integer) = Vector{UInt8}(n)
+else
+    using Base: StringVector
+end
+
 include("to-be-deprecated.jl")
 
 end # module Compat

test/runtests.jl

@@ -1822,6 +1822,15 @@ let zbuf = IOBuffer([0xbf, 0xc0, 0x00, 0x00, 0x40, 0x20, 0x00, 0x00,
     @test bswap(z2) ===  3.5 - 4.5im
 end
 
+# PR 19449
+using Compat: StringVector
+@test length(StringVector(5)) == 5
+@test String(fill!(StringVector(5), 0x61)) == "aaaaa"
+
+let x = fill!(StringVector(5), 0x61)
+    @test pointer(x) == pointer(Compat.UTF8String(x))
+end
+
 include("to-be-deprecated.jl")
 
 nothing