From e6c5a6372b01812465d0a31c6cc289d5d03ddef7 Mon Sep 17 00:00:00 2001
From: Chris Foster <chris42f@gmail.com>
Date: Wed, 19 Sep 2018 13:40:16 +1000
Subject: [PATCH] =?UTF-8?q?Add=20a=20line=20continuation=20character=20'?=
 =?UTF-8?q?=E2=A4=B8'?=
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Closes #27533
---
 src/julia-parser.scm             | 13 +++++++++++++
 stdlib/REPL/src/latex_symbols.jl |  1 +
 test/syntax.jl                   |  7 +++++++
 3 files changed, 21 insertions(+)

diff --git a/src/julia-parser.scm b/src/julia-parser.scm
index 9d832894f9bb1..bd75855f45ca7 100644
--- a/src/julia-parser.scm
+++ b/src/julia-parser.scm
@@ -503,6 +503,18 @@
              (skip-multiline-comment port 1))
       (skip-to-eol port)))
 
+(define (maybe-continue-line port)
+  (if (not space-sensitive)
+      (error "Line continuation '⤸' is only allowed for space separated lists like macros arugments and matrix literals"))
+  (read-char port) ; Consume ⤸
+  (let ((c (peek-char port)))
+    (if (eof-object? c)
+        (error "incomplete: Line continuation '⤸' is last character in file")) ; NOTE: changing this may affect code in base/client.jl
+    (if (not (eqv? c #\newline))
+        (error (string "Line continuation '⤸' must be followed by a newline. Got \"⤸"
+                       c "\" instead"))))
+  (read-char port))
+
 (define (skip-ws-and-comments port)
   (skip-ws port #t)
   (if (eqv? (peek-char port) #\#)
@@ -530,6 +542,7 @@
           ((string.find "0123456789" c)   (read-number port #f #f))
 
           ((eqv? c #\#)                   (skip-comment port) (next-token port s))
+          ((eqv? c #\⤸)                   (maybe-continue-line port) (next-token port s))
 
           ;; . is difficult to handle; it could start a number or operator
           ((and (eqv? c #\.)
diff --git a/stdlib/REPL/src/latex_symbols.jl b/stdlib/REPL/src/latex_symbols.jl
index 6f8cf59fc22b6..e91d4acfefa76 100644
--- a/stdlib/REPL/src/latex_symbols.jl
+++ b/stdlib/REPL/src/latex_symbols.jl
@@ -107,6 +107,7 @@ const latex_symbols = Dict(
     "\\impliedby" => "⟸",
     "\\to" => "→",
     "\\euler" => "ℯ",
+    "\\linecontinuation" => "⤸",
 
     # Superscripts
     "\\^0" => "⁰",
diff --git a/test/syntax.jl b/test/syntax.jl
index 4a0c7a390850f..0c36e91c95f31 100644
--- a/test/syntax.jl
+++ b/test/syntax.jl
@@ -1719,6 +1719,13 @@ let g = @foo28900 f28900(kwarg = x->2x)
     @test g(10) == 20
 end
 
+# Line continuation - issue #27533
+@test Meta.parse("[1 ⤸\n 2]") == Expr(:hcat, 1, 2)
+@test Meta.parse("@f ⤸\n a") == Expr(:macrocall, Symbol("@f"), LineNumberNode(1, :none), :a)
+@test Meta.isexpr(Meta.parse("@f ⤸"), :incomplete)
+@test_throws ParseError("Line continuation '⤸' is only allowed for space separated lists like macros arugments and matrix literals") Meta.parse("x ⤸\n = 1")
+@test_throws ParseError("Line continuation '⤸' must be followed by a newline. Got \"⤸ \" instead") Meta.parse("@x ⤸ \n")
+
 # issue #26037
 x26037() = 10
 function test_26037()