| /* Input parser for Bison |
| |
| Copyright (C) 1984, 1986, 1989, 1992, 1998, 2000-2003, 2005-2007, |
| 2009-2015, 2018-2019 Free Software Foundation, Inc. |
| |
| This file is part of Bison, the GNU Compiler Compiler. |
| |
| This program is free software: you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation, either version 3 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| |
| #include <config.h> |
| #include "system.h" |
| |
| #include <quote.h> |
| |
| #include "complain.h" |
| #include "conflicts.h" |
| #include "files.h" |
| #include "fixits.h" |
| #include "getargs.h" |
| #include "gram.h" |
| #include "muscle-tab.h" |
| #include "reader.h" |
| #include "symlist.h" |
| #include "symtab.h" |
| #include "scan-gram.h" |
| #include "scan-code.h" |
| |
| static void prepare_percent_define_front_end_variables (void); |
| static void check_and_convert_grammar (void); |
| |
| static symbol_list *grammar = NULL; |
| static bool start_flag = false; |
| merger_list *merge_functions; |
| |
| /* Was %union seen? */ |
| bool union_seen = false; |
| |
| /* Should rules have a default precedence? */ |
| bool default_prec = true; |
| |
| /*-----------------------. |
| | Set the start symbol. | |
| `-----------------------*/ |
| |
| void |
| grammar_start_symbol_set (symbol *sym, location loc) |
| { |
| if (start_flag) |
| complain (&loc, complaint, _("multiple %s declarations"), "%start"); |
| else |
| { |
| start_flag = true; |
| startsymbol = sym; |
| startsymbol_loc = loc; |
| } |
| } |
| |
| |
| |
| /*------------------------------------------------------------------------. |
| | Return the merger index for a merging function named NAME. Records the | |
| | function, if new, in MERGER_LIST. | |
| `------------------------------------------------------------------------*/ |
| |
| static int |
| get_merge_function (uniqstr name) |
| { |
| if (! glr_parser) |
| return 0; |
| |
| merger_list *syms; |
| merger_list head; |
| int n; |
| |
| head.next = merge_functions; |
| for (syms = &head, n = 1; syms->next; syms = syms->next, n += 1) |
| if (UNIQSTR_EQ (name, syms->next->name)) |
| break; |
| if (syms->next == NULL) |
| { |
| syms->next = xmalloc (sizeof syms->next[0]); |
| syms->next->name = uniqstr_new (name); |
| /* After all symbol type declarations have been parsed, packgram invokes |
| record_merge_function_type to set the type. */ |
| syms->next->type = NULL; |
| syms->next->next = NULL; |
| merge_functions = head.next; |
| } |
| return n; |
| } |
| |
| /*-------------------------------------------------------------------------. |
| | For the existing merging function with index MERGER, record the result | |
| | type as TYPE as required by the lhs of the rule whose %merge declaration | |
| | is at DECLARATION_LOC. | |
| `-------------------------------------------------------------------------*/ |
| |
| static void |
| record_merge_function_type (int merger, uniqstr type, location declaration_loc) |
| { |
| if (merger <= 0) |
| return; |
| |
| if (type == NULL) |
| type = uniqstr_new (""); |
| |
| merger_list *merge_function; |
| int merger_find = 1; |
| for (merge_function = merge_functions; |
| merge_function != NULL && merger_find != merger; |
| merge_function = merge_function->next) |
| merger_find += 1; |
| aver (merge_function != NULL && merger_find == merger); |
| if (merge_function->type != NULL && !UNIQSTR_EQ (merge_function->type, type)) |
| { |
| int indent = 0; |
| complain_indent (&declaration_loc, complaint, &indent, |
| _("result type clash on merge function %s: " |
| "<%s> != <%s>"), |
| quote (merge_function->name), type, |
| merge_function->type); |
| indent += SUB_INDENT; |
| complain_indent (&merge_function->type_declaration_loc, complaint, |
| &indent, |
| _("previous declaration")); |
| } |
| merge_function->type = uniqstr_new (type); |
| merge_function->type_declaration_loc = declaration_loc; |
| } |
| |
| /*--------------------------------------. |
| | Free all merge-function definitions. | |
| `--------------------------------------*/ |
| |
| void |
| free_merger_functions (void) |
| { |
| merger_list *L0 = merge_functions; |
| while (L0) |
| { |
| merger_list *L1 = L0->next; |
| free (L0); |
| L0 = L1; |
| } |
| } |
| |
| |
| /*-------------------------------------------------------------------. |
| | Parse the input grammar into a one symbol_list structure. Each | |
| | rule is represented by a sequence of symbols: the left hand side | |
| | followed by the contents of the right hand side, followed by a | |
| | null pointer instead of a symbol to terminate the rule. The next | |
| | symbol is the lhs of the following rule. | |
| | | |
| | All actions are copied out, labelled by the rule number they apply | |
| | to. | |
| `-------------------------------------------------------------------*/ |
| |
| /* The (currently) last symbol of GRAMMAR. */ |
| static symbol_list *grammar_end = NULL; |
| |
| /* Append SYM to the grammar. */ |
| static symbol_list * |
| grammar_symbol_append (symbol *sym, location loc) |
| { |
| symbol_list *p = symbol_list_sym_new (sym, loc); |
| |
| if (grammar_end) |
| grammar_end->next = p; |
| else |
| grammar = p; |
| |
| grammar_end = p; |
| |
| /* A null SYM stands for an end of rule; it is not an actual |
| part of it. */ |
| if (sym) |
| ++nritems; |
| |
| return p; |
| } |
| |
| static void |
| assign_named_ref (symbol_list *p, named_ref *name) |
| { |
| symbol *sym = p->content.sym; |
| |
| if (name->id == sym->tag) |
| { |
| complain (&name->loc, Wother, |
| _("duplicated symbol name for %s ignored"), |
| quote (sym->tag)); |
| named_ref_free (name); |
| } |
| else |
| p->named_ref = name; |
| } |
| |
| |
| /* The rule currently being defined, and the previous rule. |
| CURRENT_RULE points to the first LHS of the current rule, while |
| PREVIOUS_RULE_END points to the *end* of the previous rule (NULL). */ |
| static symbol_list *current_rule = NULL; |
| static symbol_list *previous_rule_end = NULL; |
| |
| |
| /*----------------------------------------------. |
| | Create a new rule for LHS in to the GRAMMAR. | |
| `----------------------------------------------*/ |
| |
| void |
| grammar_current_rule_begin (symbol *lhs, location loc, |
| named_ref *lhs_name) |
| { |
| /* Start a new rule and record its lhs. */ |
| ++nrules; |
| previous_rule_end = grammar_end; |
| |
| current_rule = grammar_symbol_append (lhs, loc); |
| if (lhs_name) |
| assign_named_ref (current_rule, named_ref_copy (lhs_name)); |
| |
| /* Mark the rule's lhs as a nonterminal if not already so. */ |
| if (lhs->content->class == unknown_sym || lhs->content->class == pct_type_sym) |
| symbol_class_set (lhs, nterm_sym, empty_loc, false); |
| else if (lhs->content->class == token_sym) |
| complain (&loc, complaint, _("rule given for %s, which is a token"), |
| lhs->tag); |
| } |
| |
| |
| /*----------------------------------------------------------------------. |
| | A symbol should be used if either: | |
| | 1. It has a destructor. | |
| | 2. The symbol is a midrule symbol (i.e., the generated LHS | |
| | replacing a midrule action) that was assigned to or used, as in | |
| | "exp: { $$ = 1; } { $$ = $1; }". | |
| `----------------------------------------------------------------------*/ |
| |
| static bool |
| symbol_should_be_used (symbol_list const *s, bool *midrule_warning) |
| { |
| if (symbol_code_props_get (s->content.sym, destructor)->code) |
| return true; |
| if ((s->midrule && s->midrule->action_props.is_value_used) |
| || (s->midrule_parent_rule |
| && (symbol_list_n_get (s->midrule_parent_rule, |
| s->midrule_parent_rhs_index) |
| ->action_props.is_value_used))) |
| { |
| *midrule_warning = true; |
| return true; |
| } |
| return false; |
| } |
| |
| /*-----------------------------------------------------------------. |
| | Check that the rule R is properly defined. For instance, there | |
| | should be no type clash on the default action. Possibly install | |
| | the default action. | |
| `-----------------------------------------------------------------*/ |
| |
| static void |
| grammar_rule_check_and_complete (symbol_list *r) |
| { |
| /* Type check. |
| |
| If there is an action, then there is nothing we can do: the user |
| is allowed to shoot herself in the foot. |
| |
| Don't worry about the default action if $$ is untyped, since $$'s |
| value can't be used. */ |
| if (!r->action_props.code && r->content.sym->content->type_name) |
| { |
| symbol *first_rhs = r->next->content.sym; |
| /* If $$ is being set in default way, report if any type mismatch. */ |
| if (first_rhs) |
| { |
| char const *lhs_type = r->content.sym->content->type_name; |
| char const *rhs_type = |
| first_rhs->content->type_name ? first_rhs->content->type_name : ""; |
| if (!UNIQSTR_EQ (lhs_type, rhs_type)) |
| complain (&r->rhs_loc, Wother, |
| _("type clash on default action: <%s> != <%s>"), |
| lhs_type, rhs_type); |
| else |
| { |
| /* Install the default action only for C++. */ |
| const bool is_cxx = |
| STREQ (language->language, "c++") |
| || (skeleton && (STREQ (skeleton, "glr.cc") |
| || STREQ (skeleton, "lalr1.cc"))); |
| if (is_cxx) |
| { |
| code_props_rule_action_init (&r->action_props, "{ $$ = $1; }", |
| r->rhs_loc, r, |
| /* name */ NULL, |
| /* type */ NULL, |
| /* is_predicate */ false); |
| code_props_translate_code (&r->action_props); |
| } |
| } |
| } |
| /* Warn if there is no default for $$ but we need one. */ |
| else |
| complain (&r->rhs_loc, Wother, |
| _("empty rule for typed nonterminal, and no action")); |
| } |
| |
| /* Check that symbol values that should be used are in fact used. */ |
| { |
| int n = 0; |
| for (symbol_list const *l = r; l && l->content.sym; l = l->next, ++n) |
| { |
| bool midrule_warning = false; |
| if (!l->action_props.is_value_used |
| && symbol_should_be_used (l, &midrule_warning) |
| /* The default action, $$ = $1, 'uses' both. */ |
| && (r->action_props.code || (n != 0 && n != 1))) |
| { |
| warnings warn_flag = midrule_warning ? Wmidrule_values : Wother; |
| if (n) |
| complain (&l->sym_loc, warn_flag, _("unused value: $%d"), n); |
| else |
| complain (&l->rhs_loc, warn_flag, _("unset value: $$")); |
| } |
| } |
| } |
| |
| /* Check that %empty => empty rule. */ |
| if (r->percent_empty_loc.start.file |
| && r->next && r->next->content.sym) |
| { |
| complain (&r->percent_empty_loc, complaint, |
| _("%%empty on non-empty rule")); |
| fixits_register (&r->percent_empty_loc, ""); |
| } |
| |
| /* Check that empty rule => %empty. */ |
| if (!(r->next && r->next->content.sym) |
| && !r->midrule_parent_rule |
| && !r->percent_empty_loc.start.file |
| && warning_is_enabled (Wempty_rule)) |
| { |
| complain (&r->rhs_loc, Wempty_rule, _("empty rule without %%empty")); |
| if (feature_flag & feature_caret) |
| location_caret_suggestion (r->rhs_loc, "%empty", stderr); |
| location loc = r->rhs_loc; |
| loc.end = loc.start; |
| fixits_register (&loc, " %empty "); |
| } |
| |
| /* See comments in grammar_current_rule_prec_set for how POSIX |
| mandates this complaint. It's only for identifiers, so skip |
| it for char literals and strings, which are always tokens. */ |
| if (r->ruleprec |
| && r->ruleprec->tag[0] != '\'' && r->ruleprec->tag[0] != '"' |
| && r->ruleprec->content->status != declared |
| && !r->ruleprec->content->prec) |
| complain (&r->rhs_loc, Wother, |
| _("token for %%prec is not defined: %s"), r->ruleprec->tag); |
| |
| /* Check that the (main) action was not typed. */ |
| if (r->action_props.type) |
| complain (&r->rhs_loc, Wother, |
| _("only midrule actions can be typed: %s"), r->action_props.type); |
| } |
| |
| |
| /*-------------------------------------. |
| | End the currently being grown rule. | |
| `-------------------------------------*/ |
| |
| void |
| grammar_current_rule_end (location loc) |
| { |
| /* Put an empty link in the list to mark the end of this rule */ |
| grammar_symbol_append (NULL, grammar_end->rhs_loc); |
| current_rule->rhs_loc = loc; |
| } |
| |
| |
| /*-------------------------------------------------------------------. |
| | The previous action turns out to be a midrule action. Attach it | |
| | to the current rule, i.e., create a dummy symbol, attach it this | |
| | midrule action, and append this dummy nonterminal to the current | |
| | rule. | |
| `-------------------------------------------------------------------*/ |
| |
| 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, whose location is that of the midrule |
| action. Create the MIDRULE. */ |
| location dummy_loc = current_rule->action_props.location; |
| symbol *dummy = dummy_symbol_get (dummy_loc); |
| symbol_type_set(dummy, |
| current_rule->action_props.type, current_rule->action_props.location); |
| symbol_list *midrule = symbol_list_sym_new (dummy, dummy_loc); |
| |
| /* Remember named_ref of previous action. */ |
| named_ref *action_name = current_rule->action_props.named_ref; |
| |
| /* 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 location and actions to that of the DUMMY. */ |
| midrule->rhs_loc = dummy_loc; |
| code_props_rule_action_init (&midrule->action_props, |
| current_rule->action_props.code, |
| current_rule->action_props.location, |
| midrule, |
| /* name_ref */ NULL, |
| /* type */ NULL, |
| current_rule->action_props.is_predicate); |
| code_props_none_init (¤t_rule->action_props); |
| |
| midrule->expected_sr_conflicts = current_rule->expected_sr_conflicts; |
| midrule->expected_rr_conflicts = current_rule->expected_rr_conflicts; |
| current_rule->expected_sr_conflicts = -1; |
| current_rule->expected_rr_conflicts = -1; |
| |
| if (previous_rule_end) |
| previous_rule_end->next = midrule; |
| else |
| grammar = midrule; |
| |
| /* End the dummy's rule. */ |
| midrule->next = symbol_list_sym_new (NULL, dummy_loc); |
| midrule->next->next = current_rule; |
| |
| previous_rule_end = midrule->next; |
| |
| /* Insert the dummy nonterminal replacing the midrule action into |
| the current rule. Bind it to its dedicated rule. */ |
| grammar_current_rule_symbol_append (dummy, dummy_loc, |
| action_name); |
| grammar_end->midrule = midrule; |
| midrule->midrule_parent_rule = current_rule; |
| midrule->midrule_parent_rhs_index = symbol_list_length (current_rule->next); |
| } |
| |
| /* Set the precedence symbol of the current rule to PRECSYM. */ |
| |
| void |
| grammar_current_rule_prec_set (symbol *precsym, location loc) |
| { |
| /* POSIX says that any identifier is a nonterminal if it does not |
| appear on the LHS of a grammar rule and is not defined by %token |
| or by one of the directives that assigns precedence to a token. |
| We ignore this here because the only kind of identifier that |
| POSIX allows to follow a %prec is a token and because assuming |
| it's a token now can produce more logical error messages. |
| Nevertheless, grammar_rule_check_and_complete does obey what we |
| believe is the real intent of POSIX here: that an error be |
| reported for any identifier that appears after %prec but that is |
| not defined separately as a token. */ |
| symbol_class_set (precsym, token_sym, loc, false); |
| if (current_rule->ruleprec) |
| duplicate_rule_directive ("%prec", |
| current_rule->ruleprec->location, loc); |
| else |
| current_rule->ruleprec = precsym; |
| } |
| |
| /* Set %empty for the current rule. */ |
| |
| void |
| grammar_current_rule_empty_set (location loc) |
| { |
| /* If %empty is used and -Wno-empty-rule is not, then enable |
| -Wempty-rule. */ |
| if (warning_is_unset (Wempty_rule)) |
| warning_argmatch ("empty-rule", 0, 0); |
| if (current_rule->percent_empty_loc.start.file) |
| duplicate_rule_directive ("%empty", |
| current_rule->percent_empty_loc, loc); |
| else |
| current_rule->percent_empty_loc = loc; |
| } |
| |
| /* Attach dynamic precedence DPREC to the current rule. */ |
| |
| void |
| grammar_current_rule_dprec_set (int dprec, location loc) |
| { |
| if (! glr_parser) |
| complain (&loc, Wother, _("%s affects only GLR parsers"), |
| "%dprec"); |
| if (dprec <= 0) |
| complain (&loc, complaint, _("%s must be followed by positive number"), |
| "%dprec"); |
| else if (current_rule->dprec != 0) |
| duplicate_rule_directive ("%dprec", |
| current_rule->dprec_loc, loc); |
| else |
| { |
| current_rule->dprec = dprec; |
| current_rule->dprec_loc = loc; |
| } |
| } |
| |
| /* Attach a merge function NAME with argument type TYPE to current |
| rule. */ |
| |
| void |
| grammar_current_rule_merge_set (uniqstr name, location loc) |
| { |
| if (! glr_parser) |
| complain (&loc, Wother, _("%s affects only GLR parsers"), |
| "%merge"); |
| if (current_rule->merger != 0) |
| duplicate_rule_directive ("%merge", |
| current_rule->merger_declaration_loc, loc); |
| else |
| { |
| current_rule->merger = get_merge_function (name); |
| current_rule->merger_declaration_loc = loc; |
| } |
| } |
| |
| /* Attach SYM to the current rule. If needed, move the previous |
| action as a midrule action. */ |
| |
| void |
| grammar_current_rule_symbol_append (symbol *sym, location loc, |
| named_ref *name) |
| { |
| if (current_rule->action_props.code) |
| grammar_midrule_action (); |
| symbol_list *p = grammar_symbol_append (sym, loc); |
| if (name) |
| assign_named_ref (p, name); |
| if (sym->content->status == undeclared || sym->content->status == used) |
| sym->content->status = needed; |
| } |
| |
| void |
| grammar_current_rule_action_append (const char *action, location loc, |
| named_ref *name, uniqstr type) |
| { |
| if (current_rule->action_props.code) |
| grammar_midrule_action (); |
| if (type) |
| complain (&loc, Wyacc, |
| _("POSIX Yacc does not support typed midrule actions")); |
| /* After all symbol declarations have been parsed, packgram invokes |
| code_props_translate_code. */ |
| code_props_rule_action_init (¤t_rule->action_props, action, loc, |
| current_rule, |
| name, type, |
| /* is_predicate */ false); |
| } |
| |
| void |
| grammar_current_rule_predicate_append (const char *pred, location loc) |
| { |
| if (current_rule->action_props.code) |
| grammar_midrule_action (); |
| code_props_rule_action_init (¤t_rule->action_props, pred, loc, |
| current_rule, |
| NULL, NULL, |
| /* is_predicate */ true); |
| } |
| |
| /* Set the expected number of shift-reduce (reduce-reduce) conflicts for |
| * the current rule. If a midrule is encountered later, the count |
| * is transferred to it and reset in the current rule to -1. */ |
| |
| void |
| grammar_current_rule_expect_sr (int count, location loc) |
| { |
| (void) loc; |
| current_rule->expected_sr_conflicts = count; |
| } |
| |
| void |
| grammar_current_rule_expect_rr (int count, location loc) |
| { |
| if (! glr_parser) |
| complain (&loc, Wother, _("%s affects only GLR parsers"), |
| "%expect-rr"); |
| else |
| current_rule->expected_rr_conflicts = count; |
| } |
| |
| |
| /*---------------------------------------------. |
| | Build RULES and RITEM from what was parsed. | |
| `---------------------------------------------*/ |
| |
| static void |
| packgram (void) |
| { |
| int itemno = 0; |
| ritem = xnmalloc (nritems + 1, sizeof *ritem); |
| /* This sentinel is used by build_relations in gram.c. */ |
| *ritem++ = 0; |
| |
| rule_number ruleno = 0; |
| rules = xnmalloc (nrules, sizeof *rules); |
| |
| for (symbol_list *p = grammar; p; p = p->next) |
| { |
| symbol_list *lhs = p; |
| record_merge_function_type (lhs->merger, lhs->content.sym->content->type_name, |
| lhs->merger_declaration_loc); |
| /* If the midrule's $$ is set or its $n is used, remove the '$' from the |
| symbol name so that it's a user-defined symbol so that the default |
| %destructor and %printer apply. */ |
| if (lhs->midrule_parent_rule /* i.e., symbol_is_dummy (lhs->content.sym). */ |
| && (lhs->action_props.is_value_used |
| || (symbol_list_n_get (lhs->midrule_parent_rule, |
| lhs->midrule_parent_rhs_index) |
| ->action_props.is_value_used))) |
| lhs->content.sym->tag += 1; |
| |
| /* Don't check the generated rule 0. It has no action, so some rhs |
| symbols may appear unused, but the parsing algorithm ensures that |
| %destructor's are invoked appropriately. */ |
| if (lhs != grammar) |
| grammar_rule_check_and_complete (lhs); |
| |
| rules[ruleno].user_number = ruleno; |
| rules[ruleno].number = ruleno; |
| rules[ruleno].lhs = lhs->content.sym->content; |
| rules[ruleno].rhs = ritem + itemno; |
| rules[ruleno].prec = NULL; |
| rules[ruleno].dprec = lhs->dprec; |
| rules[ruleno].merger = lhs->merger; |
| rules[ruleno].precsym = NULL; |
| rules[ruleno].location = lhs->rhs_loc; |
| rules[ruleno].useful = true; |
| rules[ruleno].action = lhs->action_props.code; |
| rules[ruleno].action_loc = lhs->action_props.location; |
| rules[ruleno].is_predicate = lhs->action_props.is_predicate; |
| rules[ruleno].expected_sr_conflicts = lhs->expected_sr_conflicts; |
| rules[ruleno].expected_rr_conflicts = lhs->expected_rr_conflicts; |
| |
| /* Traverse the rhs. */ |
| { |
| size_t rule_length = 0; |
| for (p = lhs->next; p->content.sym; p = p->next) |
| { |
| ++rule_length; |
| |
| /* Don't allow rule_length == INT_MAX, since that might |
| cause confusion with strtol if INT_MAX == LONG_MAX. */ |
| if (rule_length == INT_MAX) |
| complain (&rules[ruleno].location, fatal, _("rule is too long")); |
| |
| /* item_number = symbol_number. |
| But the former needs to contain more: negative rule numbers. */ |
| ritem[itemno++] = |
| symbol_number_as_item_number (p->content.sym->content->number); |
| /* A rule gets by default the precedence and associativity |
| of its last token. */ |
| if (p->content.sym->content->class == token_sym && default_prec) |
| rules[ruleno].prec = p->content.sym->content; |
| } |
| } |
| |
| /* If this rule has a %prec, |
| the specified symbol's precedence replaces the default. */ |
| if (lhs->ruleprec) |
| { |
| rules[ruleno].precsym = lhs->ruleprec->content; |
| rules[ruleno].prec = lhs->ruleprec->content; |
| } |
| |
| /* An item ends by the rule number (negated). */ |
| ritem[itemno++] = rule_number_as_item_number (ruleno); |
| aver (itemno < ITEM_NUMBER_MAX); |
| ++ruleno; |
| aver (ruleno < RULE_NUMBER_MAX); |
| } |
| |
| aver (itemno == nritems); |
| |
| if (trace_flag & trace_sets) |
| ritem_print (stderr); |
| } |
| |
| |
| /*------------------------------------------------------------------. |
| | Read in the grammar specification and record it in the format | |
| | described in gram.h. All actions are copied into ACTION_OBSTACK, | |
| | in each case forming the body of a C function (YYACTION) which | |
| | contains a switch statement to decide which action to execute. | |
| `------------------------------------------------------------------*/ |
| |
| void |
| reader (const char *gram) |
| { |
| /* Set up symbol_table, semantic_type_table, and the built-in |
| symbols. */ |
| symbols_new (); |
| |
| gram_scanner_open (gram); |
| gram_parse (); |
| gram_scanner_close (); |
| |
| prepare_percent_define_front_end_variables (); |
| |
| if (complaint_status < status_complaint) |
| check_and_convert_grammar (); |
| } |
| |
| static void |
| prepare_percent_define_front_end_variables (void) |
| { |
| /* Set %define front-end variable defaults. */ |
| muscle_percent_define_default ("lr.keep-unreachable-state", "false"); |
| { |
| /* IELR would be a better default, but LALR is historically the |
| default. */ |
| muscle_percent_define_default ("lr.type", "lalr"); |
| char *lr_type = muscle_percent_define_get ("lr.type"); |
| if (STRNEQ (lr_type, "canonical-lr")) |
| muscle_percent_define_default ("lr.default-reduction", "most"); |
| else |
| muscle_percent_define_default ("lr.default-reduction", "accepting"); |
| free (lr_type); |
| } |
| |
| /* Check %define front-end variables. */ |
| { |
| static char const * const values[] = |
| { |
| "lr.type", "lr""(0)", "lalr", "ielr", "canonical-lr", NULL, |
| "lr.default-reduction", "most", "consistent", "accepting", NULL, |
| NULL |
| }; |
| muscle_percent_define_check_values (values); |
| } |
| } |
| |
| /* Find the first LHS which is not a dummy. */ |
| |
| static symbol * |
| find_start_symbol (void) |
| { |
| symbol_list *res = grammar; |
| /* Skip all the possible dummy rules of the first rule. */ |
| for (; symbol_is_dummy (res->content.sym); res = res->next) |
| /* Skip the LHS, and then all the RHS of the dummy rule. */ |
| for (res = res->next; res->content.sym; res = res->next) |
| continue; |
| return res->content.sym; |
| } |
| |
| |
| /*-------------------------------------------------------------. |
| | Check the grammar that has just been read, and convert it to | |
| | internal form. | |
| `-------------------------------------------------------------*/ |
| |
| static void |
| check_and_convert_grammar (void) |
| { |
| /* Grammar has been read. Do some checking. */ |
| if (nrules == 0) |
| complain (NULL, fatal, _("no rules in the input grammar")); |
| |
| /* If the user did not define her ENDTOKEN, do it now. */ |
| if (!endtoken) |
| { |
| endtoken = symbol_get ("$end", empty_loc); |
| endtoken->content->class = token_sym; |
| endtoken->content->number = 0; |
| /* Value specified by POSIX. */ |
| endtoken->content->user_token_number = 0; |
| } |
| |
| /* Report any undefined symbols and consider them nonterminals. */ |
| symbols_check_defined (); |
| |
| /* Find the start symbol if no %start. */ |
| if (!start_flag) |
| { |
| symbol *start = find_start_symbol (); |
| grammar_start_symbol_set (start, start->location); |
| } |
| |
| /* Insert the initial rule, whose line is that of the first rule |
| (not that of the start symbol): |
| |
| $accept: %start $end. */ |
| { |
| symbol_list *p = symbol_list_sym_new (accept, empty_loc); |
| p->rhs_loc = grammar->rhs_loc; |
| p->next = symbol_list_sym_new (startsymbol, empty_loc); |
| p->next->next = symbol_list_sym_new (endtoken, empty_loc); |
| p->next->next->next = symbol_list_sym_new (NULL, empty_loc); |
| p->next->next->next->next = grammar; |
| nrules += 1; |
| nritems += 3; |
| grammar = p; |
| } |
| |
| aver (nsyms <= SYMBOL_NUMBER_MAXIMUM); |
| aver (nsyms == ntokens + nvars); |
| |
| /* Assign the symbols their symbol numbers. */ |
| symbols_pack (); |
| |
| /* Scan rule actions after invoking symbol_check_alias_consistency (in |
| symbols_pack above) so that token types are set correctly before the rule |
| action type checking. |
| |
| Before invoking grammar_rule_check_and_complete (in packgram |
| below) on any rule, make sure all actions have already been |
| scanned in order to set 'used' flags. Otherwise, checking that a |
| midrule's $$ should be set will not always work properly because |
| the check must forward-reference the midrule's parent rule. For |
| the same reason, all the 'used' flags must be set before checking |
| whether to remove '$' from any midrule symbol name (also in |
| packgram). */ |
| for (symbol_list *sym = grammar; sym; sym = sym->next) |
| code_props_translate_code (&sym->action_props); |
| |
| /* Convert the grammar into the format described in gram.h. */ |
| packgram (); |
| |
| /* The grammar as a symbol_list is no longer needed. */ |
| symbol_list_free (grammar); |
| } |
