parse.lac: document.

[bison.git] / ChangeLog

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+2010-12-19  Joel E. Denny  <jdenny@clemson.edu>
+
+       parse.lac: document.
+       * NEWS (2.5): Add entry for LAC, and mention LAC in entry for
+       other corrections to verbose syntax error messages.
+       * doc/bison.texinfo (Decl Summary): Rewrite entries for
+       lr.default-reductions and lr.type to be clearer, to mention
+       %nonassoc's effect on canonical LR, and to mention LAC.  Add entry
+       for parse.lac.
+       (Glossary): Add entry for LAC.
+
+2010-12-11  Joel E. Denny  <jdenny@clemson.edu>
+
+       parse.lac: implement exploratory stack reallocations.
+       * data/yacc.c: Rename %define variable parse.lac.es-capacity to
+       parse.lac.es-capacity-initial.  Accept parse.lac.memory-trace
+       with values of "failures" (default) or "full".
+       (b4_declare_parser_state_variables): Add yyesa, yyes, and
+       yyes_capacity variables.
+       (YYSTACK_USE_ALLOCA): Ignore it if LAC requested.
+       (YYSTACK_ALLOC, YYSTACK_FREE, YYSTACK_ALLOC_MAXIMUM): Define if
+       LAC requested.
+       (YYCOPY_NEEDED): New cpp macro.
+       (YYCOPY): Define if LAC requested.
+       (yy_lac_stack_realloc): New function implementing stack
+       reallocations.  Use YYMAXDEPTH for maximum stack size given that
+       the stack should never need to grow larger than the main state
+       stack needs to grow without LAC.
+       (YY_LAC_ESTABLISH): Update yy_lac invocation.
+       (yy_lac): Add arguments for exploratory stack memory data
+       recorded in the main parser.  Invoke yy_lac_stack_realloc when
+       reallocation is necessary.
+       (yysyntax_error): Add the same new arguments and pass them to
+       yy_lac.
+       (yypstate_delete): Free yyes if necessary.
+       (yyesa, yyes, yyes_capacity): #define these to yypstate members
+       in the case of push parsing.
+       (yyparse, yypush_parse): Initialize yyes and yyes_capacity.
+       Update yysyntax_error invocations.  At yyreturn, free yyes if
+       necessary.
+       * src/parse-gram.y: %define parse.lac full.
+       * tests/input.at (LAC: errors for %define): Extend for
+       parse.lac-memory-trace.
+       * tests/regression.at (LAC: Exploratory stack): Extend to check
+       that stack reallocs happen when expected.
+       (LAC: Memory exhaustion): Update to use YYMAXDEPTH and
+       parse.lac.es-capacity-initial.
+
+2010-12-11  Joel E. Denny  <jdenny@clemson.edu>
+
+       parse.lac: implement as %define variable.
+       LAC = lookahead correction.  See discussion at
+       <http://lists.gnu.org/archive/html/bison-patches/2009-09/msg00034.html>.
+       However, one point there must be corrected: because of %nonassoc,
+       LAC is *not* always redundant for lr.type=canonical-lr.
+       * data/yacc.c: Accept values of "none" (default) or "full" for
+       parse.lac.  Accept %define parse.lac.es-capacity to specify
+       capacity of LAC's temporary exploratory stack.  It defaults to 20
+       and, for now, will not grow dynamically.
+       (b4_lac_flag, b4_lac_if): New m4 macros.  Evaluate as true for
+       parse.lac!=none.
+       (YYBACKUP): Invoke YY_LAC_DISCARD.
+       (YY_LAC_ESTABLISH, YY_LAC_DISCARD): New cpp macros that invoke
+       yy_lac and track when it needs to be invoked
+       (yy_lac): New function that, given the current stack, determines
+       whether a token can eventually be shifted.  Return status mimics
+       yyparse return status.
+       (yysyntax_error): Change yystate argument to yyssp so stack top
+       can be passed to yy_lac.  If LAC is requested, build expected
+       token list by invoking yy_lac for every token instead of just
+       checking the current state for lookaheads.  Return 2 if yy_lac
+       exhausts memory.
+       (yyparse, yypush_parse): Use local variable yy_lac_established and
+       cpp macros YY_LAC_ESTABLISH and YY_LAC_DISCARD to implement LAC.
+       Update yysyntax_error invocation.  Add yyexhaustedlab code if LAC
+       is requested.
+       * tests/conflicts.at (%nonassoc and eof): Extend to check the
+       effect of each of -Dlr.type=canonical-lr and -Dparse.lac=full.
+       (%error-verbose and consistent errors): Likewise.
+       (LAC: %nonassoc requires splitting canonical LR states): New test
+       group demonstrating how LAC can fix canonical LR.
+       * tests/input.at (LAC: Errors for %define): New test group.
+       * tests/regression.at (LAC: Exploratory stack): New test group.
+       (LAC: Memory exhaustion): New test group.
+
 2010-11-21  Joel E. Denny  <jdenny@clemson.edu>
 
        build: use gnulib's new bootstrap_sync option.