From 767ea34a1d5d39f1f618a8e154c328a886de5219 Mon Sep 17 00:00:00 2001
From: Kenta Sato <bicycle1885@gmail.com>
Date: Thu, 8 Feb 2018 13:17:19 +0900
Subject: [PATCH 1/8] add sizehint keyword argument to IOBuffer

---
 base/iobuffer.jl | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/base/iobuffer.jl b/base/iobuffer.jl
index 422092f9ccd18..cffc42abf56d0 100644
--- a/base/iobuffer.jl
+++ b/base/iobuffer.jl
@@ -40,6 +40,7 @@ It may take optional keyword arguments:
 - `read`, `write`, `append`: restricts operations to the buffer; see `open` for details.
 - `truncate`: truncates the buffer size to zero length.
 - `maxsize`: specifies a size beyond which the buffer may not be grown.
+- `sizehint`: suggests a capacity of the buffer (`data` must implement `sizehint!(data, size)`).
 
 When `data` is not given, the buffer will be both readable and writable by default.
 
@@ -84,10 +85,14 @@ function IOBuffer(
         write::Union{Bool,Nothing}=nothing,
         append::Union{Bool,Nothing}=nothing,
         truncate::Union{Bool,Nothing}=nothing,
-        maxsize::Integer=typemax(Int))
+        maxsize::Integer=typemax(Int),
+        sizehint::Union{Integer,Nothing}=nothing)
     if maxsize < 0
         throw(ArgumentError("negative maxsize: $(maxsize)"))
     end
+    if sizehint !== nothing
+        sizehint!(data, sizehint)
+    end
     flags = open_flags(read=read, write=write, append=append, truncate=truncate)
     buf = GenericIOBuffer(data, flags.read, flags.write, true, flags.append, Int(maxsize))
     if flags.truncate
@@ -101,8 +106,9 @@ function IOBuffer(;
         write::Union{Bool,Nothing}=true,
         append::Union{Bool,Nothing}=nothing,
         truncate::Union{Bool,Nothing}=true,
-        maxsize::Integer=typemax(Int))
-    size = maxsize == typemax(Int) ? 32 : Int(maxsize)
+        maxsize::Integer=typemax(Int),
+        sizehint::Union{Integer,Nothing}=nothing)
+    size = maxsize != typemax(Int) ? Int(maxsize) : sizehint !== nothing ? Int(sizehint) : 32
     flags = open_flags(read=read, write=write, append=append, truncate=truncate)
     buf = IOBuffer(
         StringVector(size),

From 19d9b342eb02dd550c807f382b62e4bb122046bd Mon Sep 17 00:00:00 2001
From: Kenta Sato <bicycle1885@gmail.com>
Date: Thu, 8 Feb 2018 17:02:02 +0900
Subject: [PATCH 2/8] use sizehint in Base

---
 base/strings/basic.jl | 4 ++--
 base/strings/io.jl    | 6 +++---
 base/strings/util.jl  | 2 +-
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/base/strings/basic.jl b/base/strings/basic.jl
index a747ac39e5b8e..7e23b39a812f9 100644
--- a/base/strings/basic.jl
+++ b/base/strings/basic.jl
@@ -512,7 +512,7 @@ isascii(s::AbstractString) = all(isascii, s)
 ## string map, filter, has ##
 
 function map(f, s::AbstractString)
-    out = IOBuffer(StringVector(sizeof(s)), read=true, write=true)
+    out = IOBuffer(sizehint=sizeof(s), read=true, write=true)
     truncate(out, 0)
     for c in s
         c′ = f(c)
@@ -525,7 +525,7 @@ function map(f, s::AbstractString)
 end
 
 function filter(f, s::AbstractString)
-    out = IOBuffer(StringVector(sizeof(s)), read=true, write=true)
+    out = IOBuffer(sizehint=sizeof(s), read=true, write=true)
     truncate(out, 0)
     for c in s
         f(c) && write(out, c)
diff --git a/base/strings/io.jl b/base/strings/io.jl
index 97dbf4eed89e6..8c7bb64bf2aae 100644
--- a/base/strings/io.jl
+++ b/base/strings/io.jl
@@ -81,7 +81,7 @@ julia> sprint(showcompact, 66.66666)
 ```
 """
 function sprint(f::Function, args...; context=nothing, sizehint::Integer=0)
-    s = IOBuffer(StringVector(sizehint), read=true, write=true)
+    s = IOBuffer(sizehint=sizehint, read=true, write=true)
     # specialized version of truncate(s,0)
     s.size = 0
     s.ptr = 1
@@ -100,7 +100,7 @@ tostr_sizehint(x::Float32) = 12
 
 function print_to_string(xs...; env=nothing)
     # specialized for performance reasons
-    s = IOBuffer(StringVector(tostr_sizehint(xs[1])), read=true, write=true)
+    s = IOBuffer(sizehint=tostr_sizehint(xs[1]), read=true, write=true)
     # specialized version of truncate(s,0)
     s.size = 0
     s.ptr = 1
@@ -436,7 +436,7 @@ Returns:
 function unindent(str::AbstractString, indent::Int; tabwidth=8)
     indent == 0 && return str
     # Note: this loses the type of the original string
-    buf = IOBuffer(StringVector(sizeof(str)), read=true, write=true)
+    buf = IOBuffer(sizehint=sizeof(str), read=true, write=true)
     truncate(buf,0)
     cutting = true
     col = 0     # current column (0 based)
diff --git a/base/strings/util.jl b/base/strings/util.jl
index 9fe05fe6edcf5..d9a8c7d6806f1 100644
--- a/base/strings/util.jl
+++ b/base/strings/util.jl
@@ -383,7 +383,7 @@ function replace(str::String, pat_repl::Pair; count::Integer=typemax(Int))
     i = a = firstindex(str)
     r = coalesce(findnext(pattern,str,i), 0)
     j, k = first(r), last(r)
-    out = IOBuffer(StringVector(floor(Int, 1.2sizeof(str))), read=true, write=true)
+    out = IOBuffer(sizehint=floor(Int, 1.2sizeof(str)), read=true, write=true)
     out.size = 0
     out.ptr = 1
     while j != 0

From f24f51d1de0458df59f1b67f934a3d6548f54b97 Mon Sep 17 00:00:00 2001
From: Kenta Sato <bicycle1885@gmail.com>
Date: Thu, 8 Feb 2018 17:13:36 +0900
Subject: [PATCH 3/8] fix NEWS.md

---
 NEWS.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/NEWS.md b/NEWS.md
index fd68ecce6d5ed..2638f35c77490 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -581,6 +581,9 @@ Library improvements
     like other `AbstractDict` subtypes and its constructors mirror the
     ones of `Dict`. ([#25210])
 
+  * `IOBuffer` can take the `sizehint` keyword argument to suggest a capacity of
+    the buffer ([#?????]).
+
 Compiler/Runtime improvements
 -----------------------------
 

From 2e3f5e89c278e45207d920284e06565be875cf59 Mon Sep 17 00:00:00 2001
From: Kenta Sato <bicycle1885@gmail.com>
Date: Thu, 8 Feb 2018 17:58:04 +0900
Subject: [PATCH 4/8] fill PR serial [ci skip]

---
 NEWS.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/NEWS.md b/NEWS.md
index 2638f35c77490..ee9345f0e077b 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -582,7 +582,7 @@ Library improvements
     ones of `Dict`. ([#25210])
 
   * `IOBuffer` can take the `sizehint` keyword argument to suggest a capacity of
-    the buffer ([#?????]).
+    the buffer ([#25944]).
 
 Compiler/Runtime improvements
 -----------------------------

From 231146dd9cc5f61aaa5af1ab798d21f3f7bec90d Mon Sep 17 00:00:00 2001
From: Kenta Sato <bicycle1885@gmail.com>
Date: Fri, 9 Feb 2018 11:09:13 +0900
Subject: [PATCH 5/8] remove redundant arguments and operations

---
 base/strings/basic.jl | 6 ++----
 base/strings/io.jl    | 7 +++----
 base/strings/util.jl  | 4 +---
 3 files changed, 6 insertions(+), 11 deletions(-)

diff --git a/base/strings/basic.jl b/base/strings/basic.jl
index 7e23b39a812f9..6e83d9f263f4b 100644
--- a/base/strings/basic.jl
+++ b/base/strings/basic.jl
@@ -512,8 +512,7 @@ isascii(s::AbstractString) = all(isascii, s)
 ## string map, filter, has ##
 
 function map(f, s::AbstractString)
-    out = IOBuffer(sizehint=sizeof(s), read=true, write=true)
-    truncate(out, 0)
+    out = IOBuffer(sizehint=sizeof(s))
     for c in s
         c′ = f(c)
         isa(c′, Char) || throw(ArgumentError(
@@ -525,8 +524,7 @@ function map(f, s::AbstractString)
 end
 
 function filter(f, s::AbstractString)
-    out = IOBuffer(sizehint=sizeof(s), read=true, write=true)
-    truncate(out, 0)
+    out = IOBuffer(sizehint=sizeof(s))
     for c in s
         f(c) && write(out, c)
     end
diff --git a/base/strings/io.jl b/base/strings/io.jl
index 8c7bb64bf2aae..074d1329266de 100644
--- a/base/strings/io.jl
+++ b/base/strings/io.jl
@@ -81,7 +81,7 @@ julia> sprint(showcompact, 66.66666)
 ```
 """
 function sprint(f::Function, args...; context=nothing, sizehint::Integer=0)
-    s = IOBuffer(sizehint=sizehint, read=true, write=true)
+    s = IOBuffer(sizehint=sizehint)
     # specialized version of truncate(s,0)
     s.size = 0
     s.ptr = 1
@@ -100,7 +100,7 @@ tostr_sizehint(x::Float32) = 12
 
 function print_to_string(xs...; env=nothing)
     # specialized for performance reasons
-    s = IOBuffer(sizehint=tostr_sizehint(xs[1]), read=true, write=true)
+    s = IOBuffer(sizehint=tostr_sizehint(xs[1]))
     # specialized version of truncate(s,0)
     s.size = 0
     s.ptr = 1
@@ -436,8 +436,7 @@ Returns:
 function unindent(str::AbstractString, indent::Int; tabwidth=8)
     indent == 0 && return str
     # Note: this loses the type of the original string
-    buf = IOBuffer(sizehint=sizeof(str), read=true, write=true)
-    truncate(buf,0)
+    buf = IOBuffer(sizehint=sizeof(str))
     cutting = true
     col = 0     # current column (0 based)
     for ch in str
diff --git a/base/strings/util.jl b/base/strings/util.jl
index d9a8c7d6806f1..9d6839665d053 100644
--- a/base/strings/util.jl
+++ b/base/strings/util.jl
@@ -383,9 +383,7 @@ function replace(str::String, pat_repl::Pair; count::Integer=typemax(Int))
     i = a = firstindex(str)
     r = coalesce(findnext(pattern,str,i), 0)
     j, k = first(r), last(r)
-    out = IOBuffer(sizehint=floor(Int, 1.2sizeof(str)), read=true, write=true)
-    out.size = 0
-    out.ptr = 1
+    out = IOBuffer(sizehint=floor(Int, 1.2sizeof(str)))
     while j != 0
         if i == a || i <= k
             unsafe_write(out, pointer(str, i), UInt(j-i))

From 65f45fb819846283591bd9a8af2e8e70a4237f2c Mon Sep 17 00:00:00 2001
From: Kenta Sato <bicycle1885@gmail.com>
Date: Fri, 9 Feb 2018 11:20:33 +0900
Subject: [PATCH 6/8] fixup! remove redundant arguments and operations

---
 base/strings/io.jl | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/base/strings/io.jl b/base/strings/io.jl
index 074d1329266de..36319b0c3f646 100644
--- a/base/strings/io.jl
+++ b/base/strings/io.jl
@@ -82,9 +82,6 @@ julia> sprint(showcompact, 66.66666)
 """
 function sprint(f::Function, args...; context=nothing, sizehint::Integer=0)
     s = IOBuffer(sizehint=sizehint)
-    # specialized version of truncate(s,0)
-    s.size = 0
-    s.ptr = 1
     if context !== nothing
         f(IOContext(s, context), args...)
     else
@@ -101,9 +98,6 @@ tostr_sizehint(x::Float32) = 12
 function print_to_string(xs...; env=nothing)
     # specialized for performance reasons
     s = IOBuffer(sizehint=tostr_sizehint(xs[1]))
-    # specialized version of truncate(s,0)
-    s.size = 0
-    s.ptr = 1
     if env !== nothing
         env_io = IOContext(s, env)
         for x in xs

From 4ee880bf4bc8ee30dcbb19772224d7c6b5601598 Mon Sep 17 00:00:00 2001
From: Kenta Sato <bicycle1885@gmail.com>
Date: Fri, 9 Feb 2018 15:44:32 +0900
Subject: [PATCH 7/8] check the length of arguments for safety

---
 base/strings/io.jl | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/base/strings/io.jl b/base/strings/io.jl
index 36319b0c3f646..86009bd456e27 100644
--- a/base/strings/io.jl
+++ b/base/strings/io.jl
@@ -96,6 +96,9 @@ tostr_sizehint(x::Float64) = 20
 tostr_sizehint(x::Float32) = 12
 
 function print_to_string(xs...; env=nothing)
+    if isempty(xs)
+        return ""
+    end
     # specialized for performance reasons
     s = IOBuffer(sizehint=tostr_sizehint(xs[1]))
     if env !== nothing

From 0103483f6188a9c8ee6aaba5e1f03d3865daf260 Mon Sep 17 00:00:00 2001
From: Kenta Sato <bicycle1885@gmail.com>
Date: Fri, 9 Feb 2018 23:21:00 +0900
Subject: [PATCH 8/8] make sizehint higer precedence than maxsize

---
 base/iobuffer.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/base/iobuffer.jl b/base/iobuffer.jl
index cffc42abf56d0..b19b9b3a782bd 100644
--- a/base/iobuffer.jl
+++ b/base/iobuffer.jl
@@ -108,7 +108,7 @@ function IOBuffer(;
         truncate::Union{Bool,Nothing}=true,
         maxsize::Integer=typemax(Int),
         sizehint::Union{Integer,Nothing}=nothing)
-    size = maxsize != typemax(Int) ? Int(maxsize) : sizehint !== nothing ? Int(sizehint) : 32
+    size = sizehint !== nothing ? Int(sizehint) : maxsize != typemax(Int) ? Int(maxsize) : 32
     flags = open_flags(read=read, write=write, append=append, truncate=truncate)
     buf = IOBuffer(
         StringVector(size),