From 98258ae661e5df0fb168a1a4cb247a33977ed10c Mon Sep 17 00:00:00 2001
From: Jeff Bezanson <jeff.bezanson@gmail.com>
Date: Tue, 16 May 2017 17:44:12 -0400
Subject: [PATCH] copy-free delegating of rest keywords

---
 base/boot.jl         |  2 --
 base/essentials.jl   |  6 +++++-
 base/methodshow.jl   |  2 +-
 src/julia-syntax.scm | 10 +++++++++-
 4 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/base/boot.jl b/base/boot.jl
index d0a686e761bf50..8440465167315d 100644
--- a/base/boot.jl
+++ b/base/boot.jl
@@ -147,8 +147,6 @@ export
     # constants
     nothing, Main
 
-const AnyVector = Array{Any,1}
-
 abstract type Number end
 abstract type Real     <: Number end
 abstract type AbstractFloat <: Real end
diff --git a/base/essentials.jl b/base/essentials.jl
index 805fa564ef2a1e..0e4299f7032a5c 100644
--- a/base/essentials.jl
+++ b/base/essentials.jl
@@ -336,7 +336,9 @@ function vector_any(xs::ANY...)
     a
 end
 
-function as_kwargs(xs::Union{AbstractArray,Associative})
+as_kwargs(xs::Union{AbstractArray,Associative}) = collect_as_kwargs(xs)
+
+function collect_as_kwargs(xs::Union{AbstractArray,Associative})
     n = length(xs)
     to = Vector{Any}(n*2)
     i = 1
@@ -382,6 +384,8 @@ end
 const KWDict = ImmutableDict{Symbol,Any}
 const EmptyKWDict = KWDict()
 
+as_kwargs(xs::KWDict) = xs
+
 """
     ImmutableDict
 
diff --git a/base/methodshow.jl b/base/methodshow.jl
index c9f304a509c9e9..a258b9df7b6270 100644
--- a/base/methodshow.jl
+++ b/base/methodshow.jl
@@ -67,7 +67,7 @@ function arg_decl_parts(m::Method)
 end
 
 function kwarg_decl(m::Method, kwtype::DataType)
-    sig = rewrap_unionall(Tuple{kwtype, Core.AnyVector, unwrap_unionall(m.sig).parameters...}, m.sig)
+    sig = rewrap_unionall(Tuple{kwtype, Any, unwrap_unionall(m.sig).parameters...}, m.sig)
     kwli = ccall(:jl_methtable_lookup, Any, (Any, Any, UInt), kwtype.name.mt, sig, typemax(UInt))
     if kwli !== nothing
         kwli = kwli::Method
diff --git a/src/julia-syntax.scm b/src/julia-syntax.scm
index ef42464fc7cc29..0f5e2f18b3f840 100644
--- a/src/julia-syntax.scm
+++ b/src/julia-syntax.scm
@@ -472,7 +472,7 @@
           `((|::|
              ;; if there are optional positional args, we need to be able to reference the function name
              ,(if (any kwarg? pargl) (gensy) UNUSED)
-             (call (core kwftype) ,ftype)) (:: ,kw (core AnyVector)) ,@pargl ,@vararg)
+             (call (core kwftype) ,ftype)) ,kw ,@pargl ,@vararg)
           `(block
             ;; initialize keyword args to their defaults, or set a flag telling
             ;; whether this keyword needs to be set.
@@ -486,6 +486,13 @@
                    flags)
             ,@(if (null? restkw) '()
                   `((= ,rkw (top EmptyKWDict))))
+            ,(if (and (not (null? restkw)) (null? keynames))
+                 `(if (call (core isa) ,kw (top KWDict))
+                      (block
+                       (= ,rkw ,kw)  ;; reuse kwarg list for delegation if possible
+                       (symbolicgoto do_call)))
+                 `(if (call (core isa) ,kw (top KWDict))
+                      (= ,kw (call (top collect_as_kwargs) ,kw))))
             ;; for i = 1:(length(kw)>>1)
             (for (= ,i (: (call (top >>) (call (top length) ,kw) 1) -1 1))
                  (block
@@ -546,6 +553,7 @@
                                 '()
                                 `((if ,flag (= ,name ,dflt)))))
                           keynames vals flags))
+            (symboliclabel do_call)
             ;; finally, call the core function
             (return (call ,mangled
                           ,@keynames