Fix for parsing prop=!value

This was misparsed as `=!` infix op, which is not disallowed.

Author: andreypopp

mlx/lexer.mll

@@ -340,6 +340,8 @@ let identchar_latin1 =
 
 let symbolchar =
   ['!' '$' '%' '&' '*' '+' '-' '.' '/' ':' '<' '=' '>' '?' '@' '^' '|' '~']
+let symbolchar_no_prefix =
+  ['$' '%' '&' '*' '+' '-' '.' '/' ':' '<' '=' '>' '?' '@' '^' '|' '~']
 let symbolchar_no_greater =
   ['!' '$' '%' '&' '*' '+' '-' '.' '/' ':' '<' '=' '?' '@' '^' '|' '~']
 let symbolchar_no_less =
@@ -576,7 +578,9 @@ rule token = parse
             { PREFIXOP op }
   | ['~' '?'] symbolchar_or_hash + as op
             { PREFIXOP op }
-  | ['=' '<' '|' '&' '$'] symbolchar * as op
+  | ['<' '|' '&' '$'] symbolchar * as op
+            { INFIXOP0 op }
+  | '=' symbolchar_no_prefix * as op
             { INFIXOP0 op }
   | ">" symbolchar_no_less * as op
             { INFIXOP0 op }

ocamlmerlin_mlx/preprocess/lexer_raw.mll

@@ -354,6 +354,8 @@ let symbolchar =
   ['!' '$' '%' '&' '*' '+' '-' '.' '/' ':' '<' '=' '>' '?' '@' '^' '|' '~']
 let symbolcharnopercent =
   ['!' '$' '&' '*' '+' '-' '.' '/' ':' '<' '=' '>' '?' '@' '^' '|' '~']
+let symbolchar_no_prefix =
+  ['$' '%' '&' '*' '+' '-' '.' '/' ':' '<' '=' '>' '?' '@' '^' '|' '~']
 let symbolchar_no_greater =
   ['!' '$' '%' '&' '*' '+' '-' '.' '/' ':' '<' '=' '?' '@' '^' '|' '~']
 let symbolchar_no_less =
@@ -608,7 +610,10 @@ rule token state = parse
             { return (PREFIXOP op) }
   | ['~' '?'] symbolchar_or_hash + as op
             { return (PREFIXOP op) }
-  | ['=' '<' '|' '&' '$'] symbolchar * as op
+  | ['<' '|' '&' '$'] symbolchar * as op
+            { return (keyword_or state op
+                       (INFIXOP0 op)) }
+  | '=' symbolchar_no_prefix * as op
             { return (keyword_or state op
                        (INFIXOP0 op)) }
   | ">" symbolchar_no_less * as op

test/mlx.t

@@ -59,6 +59,8 @@
   MERLIN
   let _ = Hello.Ok.createElement () ~children:[ world ] [@JSX]
 
+Expected error (tag mismatch):
+
   $ echo 'let _ = <one>world</two>' | ./mlx
   BATCH
   File "*stdin*", line 1, characters 18-24:
@@ -71,3 +73,45 @@
   Error: Syntax error: '</one>' expected
     This '<one>' might be unmatched
 
+Some tests for prop expressions:
+
+  $ echo 'let _ = <element prop=`Some />' | ./mlx
+  BATCH
+  let _ = element () ~children:[] ~prop:`Some [@JSX]
+  MERLIN
+  let _ = element () ~children:[] ~prop:`Some [@JSX]
+  $ echo 'let _ = <element prop=Some.value />' | ./mlx
+  BATCH
+  let _ = element () ~children:[] ~prop:Some.value [@JSX]
+  MERLIN
+  let _ = element () ~children:[] ~prop:Some.value [@JSX]
+  $ echo 'let _ = <element prop=() />' | ./mlx
+  BATCH
+  let _ = element () ~children:[] ~prop:() [@JSX]
+  MERLIN
+  let _ = element () ~children:[] ~prop:() [@JSX]
+  $ echo 'let _ = <element prop=(1+2) />' | ./mlx
+  BATCH
+  let _ = element () ~children:[] ~prop:(1 + 2) [@JSX]
+  MERLIN
+  let _ = element () ~children:[] ~prop:(1 + 2) [@JSX]
+  $ echo 'let _ = <element prop=[] />' | ./mlx
+  BATCH
+  let _ = element () ~children:[] ~prop:[] [@JSX]
+  MERLIN
+  let _ = element () ~children:[] ~prop:[] [@JSX]
+  $ echo 'let _ = <element prop=name#obj />' | ./mlx
+  BATCH
+  let _ = element () ~children:[] ~prop:name#obj [@JSX]
+  MERLIN
+  let _ = element () ~children:[] ~prop:name#obj [@JSX]
+  $ echo 'let _ = <element prop=!ref />' | ./mlx
+  BATCH
+  let _ = element () ~children:[] ~prop:!ref [@JSX]
+  MERLIN
+  let _ = element () ~children:[] ~prop:!ref [@JSX]
+  $ echo 'let _ = <element prop=!?ref />' | ./mlx
+  BATCH
+  let _ = element () ~children:[] ~prop:!?ref [@JSX]
+  MERLIN
+  let _ = element () ~children:[] ~prop:!?ref [@JSX]