parse { } expressions as braces and bracescat

part of #8470

Author: JeffBezanson

NEWS.md

@@ -26,6 +26,9 @@ Language changes
   * The parsing of `1<<2*3` as `1<<(2*3)` is deprecated, and will change to
     `(1<<2)*3` in a future version ([#13079]).
 
+  * `{ }` expressions now use `braces` and `bracescat` as expression heads instead
+    of `cell1d` and `cell2d`, and parse similarly to `vect` and `vcat` ([#8470]).
+
 Breaking changes
 ----------------
 

base/show.jl

@@ -473,7 +473,8 @@ const all_ops = union(quoted_syms, uni_ops, expr_infix_any)
 const expr_calls  = Dict(:call => ('(',')'), :calldecl => ('(',')'),
                          :ref => ('[',']'), :curly => ('{','}'), :(.) => ('(',')'))
 const expr_parens = Dict(:tuple=>('(',')'), :vcat=>('[',']'),
-                         :hcat =>('[',']'), :row =>('[',']'), :vect=>('[',']'))
+                         :hcat =>('[',']'), :row =>('[',']'), :vect=>('[',']'),
+                         :braces=>('{','}'), :bracescat=>('{','}'))
 
 ## AST decoding helpers ##
 
@@ -751,7 +752,7 @@ function show_unquoted(io::IO, ex::Expr, indent::Int, prec::Int)
     # list (i.e. "(1, 2, 3)" or "[1, 2, 3]")
     elseif haskey(expr_parens, head)               # :tuple/:vcat
         op, cl = expr_parens[head]
-        if head === :vcat
+        if head === :vcat || head === :bracescat
             sep = "; "
         elseif head === :hcat || head === :row
             sep = " "

src/ast.scm

@@ -50,7 +50,6 @@
                  (string #\( (deparse-arglist (cdr e))
                          (if (length= e 2) #\, "")
                          #\)))
-                ((cell1d) (string #\{ (deparse-arglist (cdr e)) #\}))
                 ((call)   (string (deparse (cadr e)) #\( (deparse-arglist (cddr e)) #\)))
                 ((ref)    (string (deparse (cadr e)) #\[ (deparse-arglist (cddr e)) #\]))
                 ((curly)  (string (deparse (cadr e)) #\{ (deparse-arglist (cddr e)) #\}))
@@ -63,6 +62,9 @@
                 ((vect)   (string #\[ (deparse-arglist (cdr e)) #\]))
                 ((vcat)   (string #\[ (deparse-arglist (cdr e) ";") #\]))
                 ((hcat)   (string #\[ (deparse-arglist (cdr e) " ") #\]))
+                ((row)    (deparse-arglist (cdr e) " "))
+                ((braces)     (string #\{ (deparse-arglist (cdr e)) #\}))
+                ((bracescat)  (string #\{ (deparse-arglist (cdr e) ";") #\}))
                 ((const)  (string "const " (deparse (cadr e))))
                 ((global local)
                  (string (car e) " " (string.join (map deparse (cdr e)) ", ")))
@@ -91,7 +93,7 @@
                  (string (deparse (cadr e)) " where "
                          (if (length= e 3)
                              (deparse (caddr e))
-                             (deparse (cons 'cell1d (cddr e))))))
+                             (deparse (cons 'braces (cddr e))))))
                 ((function for while)
                  (deparse-block (string (car e) " " (deparse (cadr e)))
                                 (block-stmts (caddr e))))

src/julia-parser.scm

@@ -945,7 +945,7 @@
      (if (eq? t 'where)
          (begin (take-token s)
                 (let ((var (parse-comparison s)))
-                  (loop (if (and (pair? var) (eq? (car var) 'cell1d))
+                  (loop (if (and (pair? var) (eq? (car var) 'braces))
                             (list* 'where ex (cdr var))  ;; form `x where {T,S}`
                             (list 'where ex var))
                         (peek-token s))))
@@ -2190,25 +2190,15 @@
            (take-token s)
            (if (eqv? (require-token s) #\})
                (begin (take-token s)
-                      '(cell1d))
+                      '(braces))
                (let ((vex (parse-cat s #\} end-symbol)))
                  (if (null? vex)
-                     '(cell1d)
+                     '(braces)
                      (case (car vex)
-                       ((vect) `(cell1d ,@(cdr vex)))
-                       ((hcat) `(cell2d 1 ,(length (cdr vex)) ,@(cdr vex)))
-                       ((comprehension)      (error "{a for a in b} syntax is discontinued"))
-                       (else
-                        (if (and (pair? (cadr vex)) (eq? (caadr vex) 'row))
-                            (let ((nr (length (cdr vex)))
-                                  (nc (length (cdadr vex))))
-                              (begin
-                                `(cell2d ,nr ,nc
-                                         ,@(apply append
-                                                  ;; transpose to storage order
-                                                  (apply map list
-                                                         (map cdr (cdr vex)))))))
-                            `(cell1d ,@(cdr vex)))))))))
+                       ((vect) `(braces ,@(cdr vex)))
+                       ((hcat) `(bracescat (row ,@(cdr vex))))
+                       ((comprehension) `(braces ,@(cdr vex)))
+                       (else   `(bracescat ,@(cdr vex))))))))
 
           ;; string literal
           ((eqv? t #\")

src/julia-syntax.scm

@@ -2181,8 +2181,8 @@
      (syntax-deprecation #f "Expr(:(=>), ...)" "Expr(:call, :(=>), ...)")
      `(call => ,(expand-forms (cadr e)) ,(expand-forms (caddr e))))
 
-   'cell1d (lambda (e) (error "{ } vector syntax is discontinued"))
-   'cell2d (lambda (e) (error "{ } matrix syntax is discontinued"))
+   'braces    (lambda (e) (error "{ } vector syntax is discontinued"))
+   'bracescat (lambda (e) (error "{ } matrix syntax is discontinued"))
 
    'string
    (lambda (e) (expand-forms `(call (top string) ,@(cdr e))))

test/parse.jl

@@ -619,15 +619,16 @@ end
 @test_throws ParseError parse("--x")
 @test_throws ParseError parse("stagedfunction foo(x); end")
 
-#@test_throws ParseError parse("{1,2,3}")
-#@test_throws ParseError parse("{1 2 3 4}")
-#@test_throws ParseError parse("{1,2; 3,4}")
-@test_throws ParseError parse("{x for x in 1:10}")
-@test_throws ParseError parse("{x=>y for (x,y) in zip([1,2,3],[4,5,6])}")
-#@test_throws ParseError parse("{:a=>1, :b=>2}")
-
 @test parse("A=>B") == Expr(:call, :(=>), :A, :B)
 
+@test parse("{1,2,3}") == Expr(:braces, 1, 2, 3)
+@test parse("{1 2 3 4}") == Expr(:bracescat, Expr(:row, 1, 2, 3, 4))
+@test parse("{1 2; 3 4}") == Expr(:bracescat, Expr(:row, 1, 2), Expr(:row, 3, 4))
+@test parse("{x for x in 1:10}") == Expr(:braces, :(x for x in 1:10))
+@test parse("{x=>y for (x,y) in zip([1,2,3],[4,5,6])}") == Expr(:braces, :(x=>y for (x,y) in zip([1,2,3],[4,5,6])))
+@test parse("{:a=>1, :b=>2}") == Expr(:braces, Expr(:call, :(=>), QuoteNode(:a), 1),
+                                      Expr(:call, :(=>), QuoteNode(:b), 2))
+
 # this now is parsed as getindex(Pair{Any,Any}, ...)
 @test_throws MethodError eval(parse("(Any=>Any)[]"))
 @test_throws MethodError eval(parse("(Any=>Any)[:a=>1,:b=>2]"))

test/show.jl

@@ -591,6 +591,22 @@ test_mt(show_f5, "show_f5(A::AbstractArray{T,N}, indexes::Vararg{$Int,N})")
 @test_repr "[a;]"
 @test_repr "[a; b]"
 
+# other brackets and braces
+@test_repr "[a]"
+@test_repr "[a,b]"
+@test_repr "[a;b;c]"
+@test_repr "[a b]"
+@test_repr "[a b;]"
+@test_repr "[a b c]"
+@test_repr "[a b; c d]"
+@test_repr "{a}"
+@test_repr "{a,b}"
+@test_repr "{a;b;c}"
+@test_repr "{a b}"
+@test_repr "{a b;}"
+@test_repr "{a b c}"
+@test_repr "{a b; c d}"
+
 # Printing of :(function f end)
 @test sprint(show, :(function f end)) == ":(function f end)"
 @test_repr "function g end"