Skip to content

Commit

Permalink
make precedence of => strictly higher than = and ,. fixes #25391 (
Browse files Browse the repository at this point in the history
  • Loading branch information
JeffBezanson authored Jan 12, 2018
1 parent 052def7 commit 5726178
Show file tree
Hide file tree
Showing 3 changed files with 19 additions and 9 deletions.
2 changes: 2 additions & 0 deletions NEWS.md
Original file line number Diff line number Diff line change
Expand Up @@ -179,6 +179,8 @@ Language changes
* The syntax `using A.B` can now only be used when `A.B` is a module, and the syntax
`using A: B` can only be used for adding single bindings ([#8000]).

* `=>` now has its own precedence level, giving it strictly higher precedence than
`=` and `,` ([#25391]).

Breaking changes
----------------
Expand Down
20 changes: 11 additions & 9 deletions src/julia-parser.scm
Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,9 @@
;; be an operator.
(define prec-assignment
(append! (add-dots '(= += -= *= /= //= |\\=| ^= ÷= %= <<= >>= >>>= |\|=| &= ⊻=))
'(:= => ~ $=)))
'(:= ~ $=)))
;; comma - higher than assignment outside parentheses, lower when inside
(define prec-pair '(=>))
(define prec-conditional '(?))
(define prec-arrow (append!
'(-- -->)
Expand All @@ -34,7 +36,7 @@
(define prec-dot '(|.|))

(define prec-names '(prec-assignment
prec-conditional prec-lazy-or prec-lazy-and prec-arrow prec-comparison
prec-pair prec-conditional prec-lazy-or prec-lazy-and prec-arrow prec-comparison
prec-pipe< prec-pipe> prec-colon prec-plus prec-bitshift prec-times prec-rational
prec-power prec-decl prec-dot))

Expand Down Expand Up @@ -714,8 +716,8 @@
(if (or (eqv? nxt #\,) (eqv? nxt #\) ) (eqv? nxt #\}) (eqv? nxt #\]))
t
(begin (ts:put-back! s t spc)
(parse-assignment s parse-cond)))))
(parse-assignment s parse-cond))))
(parse-assignment s parse-pair)))))
(parse-assignment s parse-pair))))

(define (eventually-call? ex)
(and (pair? ex)
Expand All @@ -735,14 +737,12 @@
ex
(begin
(take-token s)
(cond ((eq? t '~)
(cond ((eq? t '~) ;; ~ is the only non-syntactic assignment-precedence operators
(if (and space-sensitive (ts:space? s)
(not (eqv? (peek-char (ts:port s)) #\ )))
(begin (ts:put-back! s t (ts:space? s))
ex)
(list 'call t ex (parse-assignment s down))))
((eq? t '=>) ;; ~ and => are the only non-syntactic assignment-precedence operators
(list 'call t ex (parse-assignment s down)))
((eq? t '=)
;; insert line/file for short-form function defs, otherwise leave alone
(let ((lno (input-port-line (ts:port s))))
Expand All @@ -753,7 +753,7 @@

; parse-comma is needed for commas outside parens, for example a = b,c
(define (parse-comma s)
(let loop ((ex (list (parse-cond s)))
(let loop ((ex (list (parse-pair s)))
(first? #t)
(t (peek-token s)))
(if (not (eqv? t #\,))
Expand All @@ -767,7 +767,9 @@
(begin (take-token s)
(if (or (eof-object? (peek-token s)) (eq? (peek-token s) '=))
(loop ex #f (peek-token s))
(loop (cons (parse-cond s) ex) #f (peek-token s)))))))
(loop (cons (parse-pair s) ex) #f (peek-token s)))))))

(define (parse-pair s) (parse-RtoL s parse-cond is-prec-pair? #f parse-pair))

(define (parse-cond s)
(let ((ex (parse-arrow s)))
Expand Down
6 changes: 6 additions & 0 deletions test/syntax.jl
Original file line number Diff line number Diff line change
Expand Up @@ -1246,3 +1246,9 @@ function f25055()
return x
end
@test f25055() !== f25055()

# issue #25391
@test Meta.parse("0:-1, \"\"=>\"\"") == Meta.parse("(0:-1, \"\"=>\"\")") ==
Expr(:tuple, Expr(:(:), 0, -1), Expr(:call, :(=>), "", ""))
@test Meta.parse("a => b = c") == Expr(:(=), Expr(:call, :(=>), :a, :b), Expr(:block, LineNumberNode(1, :none), :c))
@test Meta.parse("a = b => c") == Expr(:(=), :a, Expr(:call, :(=>), :b, :c))

0 comments on commit 5726178

Please sign in to comment.