grammar_end = p;
}
+/* The rule currently being defined, and the previous rule. Point to
+ the first symbol of each list: their lhs. */
+symbol_list *current_rule = NULL;
+symbol_list *previous_rule = NULL;
+
+
+/* Create a new rule for LHS in to the GRAMMAR. */
+
+static void
+grammar_rule_begin (symbol_t *lhs)
+{
+ if (!start_flag)
+ {
+ startsymbol = lhs;
+ start_flag = 1;
+ }
+
+ /* Start a new rule and record its lhs. */
+ ++nrules;
+ ++nritems;
+
+ previous_rule = grammar_end;
+ grammar_symbol_append (lhs);
+ current_rule = grammar_end;
+
+ /* Mark the rule's lhs as a nonterminal if not already so. */
+
+ if (lhs->class == unknown_sym)
+ {
+ lhs->class = nterm_sym;
+ lhs->number = nvars;
+ ++nvars;
+ }
+ else if (lhs->class == token_sym)
+ complain (_("rule given for %s, which is a token"), lhs->tag);
+}
+
+/* The previous action turns out the be a mid-rule action. Attach it
+ to the current rule, i.e., create a dummy symbol, attach it this
+ mid-rule action, and append this dummy nonterminal to the current
+ rule. */
+
+static void
+grammar_midrule_action (void)
+{
+ /* Since the action was written out with this rule's number, we must
+ give the new rule this number by inserting the new rule before
+ it. */
+
+ /* Make a dummy nonterminal, a gensym. */
+ symbol_t *sdummy = gensym ();
+ symbol_list *midrule_action = symbol_list_new (sdummy);
+
+ /* Make a new rule, whose body is empty, before the current one, so
+ that the action just read can belong to it. */
+ ++nrules;
+ ++nritems;
+ /* Attach its lineno to that of the host rule. */
+ midrule_action->line = current_rule->line;
+ /* Move the action from the host rule to this one. */
+ midrule_action->action = current_rule->action;
+ midrule_action->action_line = current_rule->action_line;
+ current_rule->action = NULL;
+
+ if (previous_rule)
+ previous_rule->next = midrule_action;
+ else
+ grammar = midrule_action;
+
+ /* End of the rule. */
+ previous_rule = symbol_list_new (NULL);
+ previous_rule->next = current_rule;
+
+ midrule_action->next = previous_rule;
+
+ /* Insert the dummy generated by that rule into this rule. */
+ ++nritems;
+ grammar_symbol_append (sdummy);
+}
+
+
static void
readgram (void)
{
token_t t;
symbol_t *lhs = NULL;
- /* Points to first symbol_list of current rule. its symbol is the
- lhs of the rule. */
- symbol_list *crule = NULL;
- /* Points to the symbol_list preceding crule. */
- symbol_list *crule1 = NULL;
-
t = lex ();
while (t != tok_two_percents && t != tok_eof)
{
lhs = symval;
- if (!start_flag)
- {
- startsymbol = lhs;
- start_flag = 1;
- }
-
t = lex ();
if (t != tok_colon)
{
unlex (t);
}
}
-
if (nrules == 0 && t == tok_bar)
{
complain (_("grammar starts with vertical bar"));
lhs = symval; /* BOGUS: use a random symval */
}
- /* start a new rule and record its lhs. */
-
- ++nrules;
- ++nritems;
-
- crule1 = grammar_end;
- grammar_symbol_append (lhs);
- crule = grammar_end;
-
- /* mark the rule's lhs as a nonterminal if not already so. */
-
- if (lhs->class == unknown_sym)
- {
- lhs->class = nterm_sym;
- lhs->number = nvars;
- ++nvars;
- }
- else if (lhs->class == token_sym)
- complain (_("rule given for %s, which is a token"), lhs->tag);
+ grammar_rule_begin (lhs);
/* read the rhs of the rule. */
for (;;)
if (t == tok_prec)
{
t = lex ();
- crule->ruleprec = symval;
+ current_rule->ruleprec = symval;
t = lex ();
}
non-terminal. */
if (action_flag)
{
- /* Since the action was written out with this rule's
- number, we must give the new rule this number by
- inserting the new rule before it. */
-
- /* Make a dummy nonterminal, a gensym. */
- symbol_t *sdummy = gensym ();
- symbol_list *p = symbol_list_new (sdummy);
-
- /* Make a new rule, whose body is empty, before the
- current one, so that the action just read can
- belong to it. */
- ++nrules;
- ++nritems;
- /* Attach its lineno to that of the host rule. */
- p->line = crule->line;
- /* Move the action from the host rule to this one. */
- p->action = crule->action;
- p->action_line = crule->action_line;
- crule->action = NULL;
-
- if (crule1)
- crule1->next = p;
- else
- grammar = p;
- /* End of the rule. */
- crule1 = symbol_list_new (NULL);
- crule1->next = crule;
-
- p->next = crule1;
-
- /* Insert the dummy generated by that rule into this
- rule. */
- ++nritems;
- grammar_symbol_append (sdummy);
+ grammar_midrule_action ();
action_flag = 0;
}
}
else /* handle an action. */
{
- parse_action (crule, rulelength);
+ parse_action (current_rule, rulelength);
action_flag = 1;
++xactions; /* JF */
}
{
complain (_("two @prec's in a row"));
t = lex ();
- crule->ruleprec = symval;
+ current_rule->ruleprec = symval;
t = lex ();
}
/* This case never occurs -wjh */
if (action_flag)
complain (_("two actions at end of one rule"));
- parse_action (crule, rulelength);
+ parse_action (current_rule, rulelength);
action_flag = 1;
++xactions; /* -wjh */
t = lex ();
projects / bison.git / blobdiff