From: Nobuyoshi Nakada <nobu@...>
Date: 2007-04-12T04:19:02+09:00
Subject: Re: memory exhausted

Hi,

At Wed, 11 Apr 2007 04:56:23 +0900,
Tim Pease wrote in [ruby-talk:247418]:
> Probably hitting a lex/yacc semantic stack limit.

Yes, it will work by increasing YYMAXDEPTH.

> I wonder if you could do the same kind of thing with a
> begin/rescue/ensure/end clause?
> 
> Hmmm ....
> 
> eval <<EOS
> begin
>   raise
> #{ (0..1999).map { "rescue;\n" }.join('') }
> end
> EOS
> 
> (eval):2003: compile error (SyntaxError)
> (eval):2003: memory exhausted

A patch to inverse the order of shift/reduce.


Index: parse.y
===================================================================
--- parse.y	(revision 12169)
+++ parse.y	(working copy)
@@ -273,5 +273,5 @@ static void top_local_setup();
 %type <node> bodystmt compstmt stmts stmt expr arg primary command command_call method_call
 %type <node> expr_value arg_value primary_value
-%type <node> if_tail opt_else case_body cases opt_rescue exc_list exc_var opt_ensure
+%type <node> if_tail opt_else case_body cases opt_rescue rescue exc_list exc_var opt_ensure
 %type <node> args when_args call_args call_args2 open_args paren_args opt_paren_args
 %type <node> command_args aref_args opt_block_arg block_arg var_ref var_lhs
@@ -376,5 +376,7 @@ bodystmt	: compstmt
 		        $$ = $1;
 			if ($2) {
-			    $$ = NEW_RESCUE($1, $2, $3);
+			    $$ = $2;
+			    $$->nd_head = $1;
+			    $$->nd_else = $3;
 			}
 			else if ($3) {
@@ -1599,14 +1601,16 @@ primary		: literal
 			}
 		    }
-		| kCASE expr_value opt_terms
-		  case_body
-		  kEND
+		| kCASE expr_value opt_terms cases opt_else kEND
 		    {
-			$$ = NEW_CASE($2, $4);
+			$4->nd_head->nd_next = $5;
+			$4->nd_head = $2;
+			$$ = $4;
 		        fixpos($$, $2);
 		    }
-		| kCASE opt_terms case_body kEND
+		| kCASE opt_terms cases opt_else kEND
 		    {
-			$$ = $3;
+			$3->nd_head->nd_next = $4;
+			$$ = $3->nd_body;
+			rb_gc_force_recycle((VALUE)$3);
 		    }
 		| kCASE opt_terms kELSE compstmt kEND
@@ -1871,7 +1875,6 @@ brace_block	: '{'
 case_body	: kWHEN when_args then
 		  compstmt
-		  cases
 		    {
-			$$ = NEW_WHEN($2, $4, $5);
+			$$ = NEW_WHEN($2, $4, 0);
 		    }
 		;
@@ -1887,11 +1890,34 @@ when_args	: args
 		;
 
-cases		: opt_else
-		| case_body
+cases		: case_body
+		    {
+			$$ = NEW_CASE($1, $1);
+		    }
+		| cases
+		  case_body
+		    {
+			$$ = $1;
+			$$->nd_head->nd_next = $2;
+			$$->nd_head = $2;
+		    }
+		;
+
+opt_rescue	: none
+		| opt_rescue
+		  rescue
+		    {
+			if ($1) {
+			    $1->nd_head->nd_head = $$;
+			    $1->nd_head = $$;
+			    $$ = $1;
+			}
+			else {
+			    $$ = NEW_RESCUE($2, $2, 0);
+			}
+		    }
 		;
 
-opt_rescue	: kRESCUE exc_list exc_var then
+rescue		: kRESCUE exc_list exc_var then
 		  compstmt
-		  opt_rescue
 		    {
 		        if ($3) {
@@ -1899,8 +1925,7 @@ opt_rescue	: kRESCUE exc_list exc_var th
 			    $5 = block_append($3, $5);
 			}
-			$$ = NEW_RESBODY($2, $5, $6);
+			$$ = NEW_RESBODY($2, $5, 0);
 		        fixpos($$, $2?$2:$5);
 		    }
-		| none
 		;
 


-- 
Nobu Nakada