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Add a unary integer negation operator

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This allows saying "-1" instead of "builtins.sub 0 1".
This commit is contained in:
Eelco Dolstra 2013-08-02 17:35:59 +02:00
parent 159e621d1a
commit 5d147e125c
3 changed files with 11 additions and 4 deletions
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6
src/libexpr/parser.y
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@ -270,11 +270,12 @@ void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * err
%left AND
%nonassoc EQ NEQ
%right UPDATE
%left NEG
%left NOT
%left '+'
%right CONCAT
%nonassoc '?'
%nonassoc '~'
%nonassoc NEGATE
%%
@ -306,7 +307,8 @@ expr_if
;
expr_op
: '!' expr_op %prec NEG { $$ = new ExprOpNot($2); }
: '!' expr_op %prec NOT { $$ = new ExprOpNot($2); }
| '-' expr_op %prec NEGATE { $$ = new ExprApp(new ExprApp(new ExprVar(data->symbols.create("__sub")), new ExprInt(0)), $2); }
| expr_op EQ expr_op { $$ = new ExprOpEq($1, $3); }
| expr_op NEQ expr_op { $$ = new ExprOpNEq($1, $3); }
| expr_op AND expr_op { $$ = new ExprOpAnd($1, $3); }

2
tests/lang/eval-okay-arithmetic.exp
View file

@ -1 +1 @@
1854
1843

7
tests/lang/eval-okay-arithmetic.nix
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@ -16,6 +16,11 @@ let {
range = range_ [];
*/
body = sum (range 1 50) + 123 + 456;
x = 12;
body = sum
[ (sum (range 1 50))
(123 + 456)
(0 + -10 + -(-11) + -x)
];
}