+/* Establish the initial context for the current lookahead if no initial
+ context is currently established.
+
+ We define a context as a snapshot of the parser stacks. We define
+ the initial context for a lookahead as the context in which the
+ parser initially examines that lookahead in order to select a
+ syntactic action. Thus, if the lookahead eventually proves
+ syntactically unacceptable (possibly in a later context reached via a
+ series of reductions), the initial context can be used to determine
+ the exact set of tokens that would be syntactically acceptable in the
+ lookahead's place. Moreover, it is the context after which any
+ further semantic actions would be erroneous because they would be
+ determined by a syntactically unacceptable token.
+
+ YY_LAC_ESTABLISH should be invoked when a reduction is about to be
+ performed in an inconsistent state (which, for the purposes of LAC,
+ includes consistent states that don't know they're consistent because
+ their default reductions have been disabled). Iff there is a
+ lookahead token, it should also be invoked before reporting a syntax
+ error. This latter case is for the sake of the debugging output.
+
+ For parse.lac=full, the implementation of YY_LAC_ESTABLISH is as
+ follows. If no initial context is currently established for the
+ current lookahead, then check if that lookahead can eventually be
+ shifted if syntactic actions continue from the current context.
+ Report a syntax error if it cannot. */
+#define YY_LAC_ESTABLISH \
+do { \
+ if (!yy_lac_established) \
+ { \
+ YYDPRINTF ((stderr, \
+ "LAC: initial context established for %s\n", \
+ yytname[yytoken])); \
+ yy_lac_established = 1; \
+ { \
+ int yy_lac_status = \
+ yy_lac (yyesa, &yyes, &yyes_capacity, yyssp, yytoken); \
+ if (yy_lac_status == 2) \
+ goto yyexhaustedlab; \
+ if (yy_lac_status == 1) \
+ goto yyerrlab; \
+ } \
+ } \
+} while (YYID (0))
+
+/* Discard any previous initial lookahead context because of Event,
+ which may be a lookahead change or an invalidation of the currently
+ established initial context for the current lookahead.
+
+ The most common example of a lookahead change is a shift. An example
+ of both cases is syntax error recovery. That is, a syntax error
+ occurs when the lookahead is syntactically erroneous for the
+ currently established initial context, so error recovery manipulates
+ the parser stacks to try to find a new initial context in which the
+ current lookahead is syntactically acceptable. If it fails to find
+ such a context, it discards the lookahead. */
+#if YYDEBUG
+# define YY_LAC_DISCARD(Event) \
+do { \
+ if (yy_lac_established) \
+ { \
+ if (yydebug) \
+ YYFPRINTF (stderr, "LAC: initial context discarded due to " \
+ Event "\n"); \
+ yy_lac_established = 0; \
+ } \
+} while (YYID (0))
+#else
+# define YY_LAC_DISCARD(Event) yy_lac_established = 0
+#endif
+
+/* Given the stack whose top is *YYSSP, return 0 iff YYTOKEN can
+ eventually (after perhaps some reductions) be shifted, return 1 if
+ not, or return 2 if memory is exhausted. As preconditions and
+ postconditions: *YYES_CAPACITY is the allocated size of the array to
+ which *YYES points, and either *YYES = YYESA or *YYES points to an
+ array allocated with YYSTACK_ALLOC. yy_lac may overwrite the
+ contents of either array, alter *YYES and *YYES_CAPACITY, and free
+ any old *YYES other than YYESA. */
+static int
+yy_lac (yytype_int16 *yyesa, yytype_int16 **yyes,
+ YYSIZE_T *yyes_capacity, yytype_int16 *yyssp, int yytoken)
+{
+ yytype_int16 *yyes_prev = yyssp;
+ yytype_int16 *yyesp = yyes_prev;
+ YYDPRINTF ((stderr, "LAC: checking lookahead %s:", yytname[yytoken]));
+ if (yytoken == YYUNDEFTOK)
+ {
+ YYDPRINTF ((stderr, " Always Err\n"));
+ return 1;
+ }
+ while (1)
+ {
+ int yyrule = yypact[*yyesp];
+ if (yypact_value_is_default (yyrule)
+ || (yyrule += yytoken) < 0 || YYLAST < yyrule
+ || yycheck[yyrule] != yytoken)
+ {
+ yyrule = yydefact[*yyesp];
+ if (yyrule == 0)
+ {
+ YYDPRINTF ((stderr, " Err\n"));
+ return 1;
+ }
+ }
+ else
+ {
+ yyrule = yytable[yyrule];
+ if (yytable_value_is_error (yyrule))
+ {
+ YYDPRINTF ((stderr, " Err\n"));
+ return 1;
+ }
+ if (0 < yyrule)
+ {
+ YYDPRINTF ((stderr, " S%d\n", yyrule));
+ return 0;
+ }
+ yyrule = -yyrule;
+ }
+ {
+ YYSIZE_T yylen = yyr2[yyrule];
+ YYDPRINTF ((stderr, " R%d", yyrule - 1));
+ if (yyesp != yyes_prev)
+ {
+ YYSIZE_T yysize = yyesp - *yyes + 1;
+ if (yylen < yysize)
+ {
+ yyesp -= yylen;
+ yylen = 0;
+ }
+ else
+ {
+ yylen -= yysize;
+ yyesp = yyes_prev;
+ }
+ }
+ if (yylen)
+ yyesp = yyes_prev -= yylen;
+ }
+ {
+ int yystate;
+ {
+ int yylhs = yyr1[yyrule] - YYNTOKENS;
+ yystate = yypgoto[yylhs] + *yyesp;
+ if (yystate < 0 || YYLAST < yystate
+ || yycheck[yystate] != *yyesp)
+ yystate = yydefgoto[yylhs];
+ else
+ yystate = yytable[yystate];
+ }
+ if (yyesp == yyes_prev)
+ {
+ yyesp = *yyes;
+ *yyesp = yystate;
+ }
+ else
+ {
+ if (yy_lac_stack_realloc (yyes_capacity, 1,
+#if YYDEBUG
+ " (", ")",
projects / bison.git / blobdiff