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authorQuentin Carbonneaux <quentin@c9x.me>2018-01-18 11:46:13 +0000
committerOri Bernstein <ori@eigenstate.org>2018-01-26 22:39:56 -0800
commit6fb0d750b296506f31cfd0871fdac82ee878834b (patch)
tree0d6bab181652f7859c6eef913285abfc41d1bc38 /parse/gram.y
parent24a566ff1751b246c8b6efd8adea3447975b9efa (diff)
downloadmc-6fb0d750b296506f31cfd0871fdac82ee878834b.tar.gz
New auto operator.
Summary: -------- During the Myrcon in September Ori suggested an 'auto' operator that would evaluate what it applies to, store the result in a temporary t, and call __dispose__(t) when the current block exits. This patch implements this idea under the form of a unary operator. This, for instance, allows to have: impl disposable regex# = __dispose__ = {r; regex.free(r)} ;; regex.exec(auto std.try(regex.compile("f..bar")), "foobar") Like before, it is guaranteed that __dispose__ is called in reverse order of auto appearance. Backward compatibility: ----------------------- Nope. Auto variables are now gone. This should not be a problem, simply rewrite: var auto x = foo() into: var x = auto foo() Implementation: --------------- It largely reuses the code I had written for 'auto' variables but needs a little finer grain tracking because we don't always want to call __dispose__ for *all* auto expression results when leaving a block (some might not be evaluated yet). For example: auto 1 if b -> void ;; auto 2 Only __dispose__(1) must be called when '-> void' is executed. If the block falls through, __dispose__(2) and __dispose__(1) will be called in sequence. TODO: ----- - Err when goto jumps in/out of a block that has auto expressions. - Support auto in patterns. match ... | `std.Some (auto x): ... is essentially rewritten to: match ... | `std.Some (auto x): auto x ... - Test edge cases (e.g., auto in loop condition) Actually, test. Cheers,
Diffstat (limited to 'parse/gram.y')
-rw-r--r--parse/gram.y15
1 files changed, 6 insertions, 9 deletions
diff --git a/parse/gram.y b/parse/gram.y
index 5c73295..adc63c4 100644
--- a/parse/gram.y
+++ b/parse/gram.y
@@ -147,7 +147,7 @@ static void setupinit(Node *n);
%type<node> littok literal lorexpr landexpr borexpr strlit bandexpr
%type<node> cmpexpr addexpr mulexpr shiftexpr prefixexpr
%type<node> postfixexpr funclit seqlit tuplit name block stmt label
-%type<node> use fnparam declbody declcore typedeclcore autodecl structent
+%type<node> use fnparam declbody declcore typedeclcore structent
%type<node> arrayelt structelt tuphead ifstmt forstmt whilestmt
%type<node> matchstmt elifs optexprln loopcond optexpr match
@@ -419,8 +419,8 @@ pkgtydef: attrs tydef {
}
;
-declbody: autodecl Tasn expr {$$ = $1; $1->decl.init = $3;}
- | autodecl
+declbody: declcore Tasn expr {$$ = $1; $1->decl.init = $3;}
+ | declcore
;
declcore: name {$$ = mkdecl($1->loc, $1, mktyvar($1->loc));}
@@ -431,10 +431,6 @@ typedeclcore
: name Tcolon type {$$ = mkdecl($1->loc, $1, $3);}
;
-autodecl: Tauto declcore {$$ = $2; $$->decl.isauto = 1;}
- | declcore
- ;
-
name : Tident {$$ = mkname($1->loc, $1->id);}
| Tident Tdot Tident {
$$ = mknsname($3->loc, $1->id, $3->id);
@@ -764,7 +760,8 @@ shiftexpr
shiftop : Tbsl | Tbsr;
prefixexpr
- : Tinc prefixexpr {$$ = mkexpr($1->loc, Opreinc, $2, NULL);}
+ : Tauto prefixexpr {$$ = mkexpr($1->loc, Oauto, $2, NULL);}
+ | Tinc prefixexpr {$$ = mkexpr($1->loc, Opreinc, $2, NULL);}
| Tdec prefixexpr {$$ = mkexpr($1->loc, Opredec, $2, NULL);}
| Tband prefixexpr {$$ = mkexpr($1->loc, Oaddr, $2, NULL);}
| Tlnot prefixexpr {$$ = mkexpr($1->loc, Olnot, $2, NULL);}
@@ -923,7 +920,7 @@ params : fnparam {
| /* empty */ {$$.nl = NULL; $$.nn = 0;}
;
-fnparam : autodecl {$$ = $1;}
+fnparam : declcore {$$ = $1;}
| Tgap { $$ = mkpseudodecl($1->loc, mktyvar($1->loc)); }
| Tgap Tcolon type { $$ = mkpseudodecl($1->loc, $3); }
;