Re: calc++ example leaks

[Paul Eggert]

"Sander Brandenburg" <address@hidden> writes:

> Below is a fix for the memory leaks. I'm only not sure the way I solve it is
> good practice, because keeping track of what needs to be deleted looks
> rather cumbersome.

Thanks for the bug report.  Yes, it is cumbersome, but I'm afraid that
for Bison right now that's life in the C++ city.  I installed this
patch to fix the upstream source (and some minor white space and
comment issues):

2006-09-11  Paul Eggert  <address@hidden>

        * doc/bison.texinfo (Calc++ Parser): Fix memory leak reported by
        Sander Brandenburg in
        <http://lists.gnu.org/archive/html/bug-bison/2006-09/msg00002.html>.
        Also, fix minor white space and comment issues.

--- doc/bison.texinfo.~1.203.~  2006-09-11 10:48:45.000000000 -0700
+++ doc/bison.texinfo   2006-09-11 10:53:30.000000000 -0700
@@ -7423,8 +7423,8 @@ factor both as follows.
 
 @comment file: calc++-driver.hh
 @example
-// Announce to Flex the prototype we want for lexing function, ...
-# define YY_DECL                                       \
+// Tell Flex the lexer's prototype ...
+# define YY_DECL                                        \
   yy::calcxx_parser::token_type                         \
   yylex (yy::calcxx_parser::semantic_type* yylval,      \
          yy::calcxx_parser::location_type* yylloc,      \
@@ -7675,7 +7675,9 @@ unit: assignments exp  @{ driver.result 
 assignments: assignments assignment @address@hidden
            | /* Nothing.  */        @address@hidden;
 
-assignment: "identifier" ":=" exp @{ driver.variables[*$1] = $3; @};
+assignment:
+     "identifier" ":=" exp
+       @{ driver.variables[*$1] = $3; delete $1; @};
 
 %left '+' '-';
 %left '*' '/';
@@ -7683,7 +7685,7 @@ exp: exp '+' exp   @{ $$ = $1 + $3; @}
    | exp '-' exp   @{ $$ = $1 - $3; @}
    | exp '*' exp   @{ $$ = $1 * $3; @}
    | exp '/' exp   @{ $$ = $1 / $3; @}
-   | "identifier"  @{ $$ = driver.variables[*$1]; @}
+   | "identifier"  @{ $$ = driver.variables[*$1]; delete $1; @}
    | "number"      @{ $$ = $1; @};
 %%
 @end example
@@ -7844,8 +7846,8 @@ main (int argc, char *argv[])
       driver.trace_scanning = true;
     else
       @{
-       driver.parse (*argv);
-       std::cout << driver.result << std::endl;
+        driver.parse (*argv);
+        std::cout << driver.result << std::endl;
       @}
 @}
 @end example