X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/97650f4efc420eb5eb0af124f28987875e10428a..c0ad8bf3c2fb46f001bb24ac98a72b8bfb3a77ce:/src/LR0.c diff --git a/src/LR0.c b/src/LR0.c index 2e347b55..7dd7b441 100644 --- a/src/LR0.c +++ b/src/LR0.c @@ -1,5 +1,7 @@ /* Generate the nondeterministic finite state machine for bison, - Copyright 1984, 1986, 1989, 2000, 2001, 2002 Free Software Foundation, Inc. + + Copyright (C) 1984, 1986, 1989, 2000, 2001, 2002 Free Software + Foundation, Inc. This file is part of Bison, the GNU Compiler Compiler. @@ -46,10 +48,28 @@ typedef struct state_list_s static state_list_t *first_state = NULL; static state_list_t *last_state = NULL; -static void -state_list_append (state_t *state) + +/*------------------------------------------------------------------. +| A state was just discovered from another state. Queue it for | +| later examination, in order to find its transitions. Return it. | +`------------------------------------------------------------------*/ + +static state_t * +state_list_append (symbol_number_t symbol, + size_t core_size, item_number_t *core) { state_list_t *node = XMALLOC (state_list_t, 1); + state_t *state = state_new (symbol, core_size, core); + + if (trace_flag & trace_automaton) + fprintf (stderr, "state_list_append (state = %d, symbol = %d (%s))\n", + nstates, symbol, symbols[symbol]->tag); + + /* If this is the endtoken, and this is not the initial state, then + this is the final state. */ + if (symbol == 0 && first_state) + final_state = state; + node->next = NULL; node->state = state; @@ -58,13 +78,15 @@ state_list_append (state_t *state) if (last_state) last_state->next = node; last_state = node; + + return state; } static int nshifts; static symbol_number_t *shift_symbol = NULL; -static short *redset = NULL; -static state_number_t *shiftset = NULL; +static rule_t **redset = NULL; +static state_t **shiftset = NULL; static item_number_t **kernel_base = NULL; static int *kernel_size = NULL; @@ -85,7 +107,7 @@ allocate_itemsets (void) int count = 0; short *symbol_count = XCALLOC (short, nsyms + nuseless_nonterminals); - for (r = 1; r < nrules + 1; ++r) + for (r = 0; r < nrules; ++r) for (rhsp = rules[r].rhs; *rhsp >= 0; ++rhsp) { count++; @@ -119,8 +141,8 @@ allocate_storage (void) { allocate_itemsets (); - shiftset = XCALLOC (state_number_t, nsyms); - redset = XCALLOC (short, nrules + 1); + shiftset = XCALLOC (state_t *, nsyms); + redset = XCALLOC (rule_t *, nrules); state_hash_new (); shift_symbol = XCALLOC (symbol_number_t, nsyms); } @@ -157,7 +179,7 @@ new_itemsets (state_t *state) { int i; - if (trace_flag) + if (trace_flag & trace_automaton) fprintf (stderr, "Entering new_itemsets, state = %d\n", state->number); @@ -185,63 +207,36 @@ new_itemsets (state_t *state) /*-----------------------------------------------------------------. -| Subroutine of get_state. Create a new state for those items, if | -| necessary. | +| Find the state we would get to (from the current state) by | +| shifting SYMBOL. Create a new state if no equivalent one exists | +| already. Used by append_states. | `-----------------------------------------------------------------*/ static state_t * -new_state (symbol_number_t symbol, size_t core_size, item_number_t *core) -{ - state_t *res; - - if (trace_flag) - fprintf (stderr, "Entering new_state, state = %d, symbol = %d (%s)\n", - nstates, symbol, symbols[symbol]->tag); - - res = state_new (symbol, core_size, core); - state_hash_insert (res); - - /* If this is the eoftoken, and this is not the initial state, then - this is the final state. */ - if (symbol == 0 && first_state) - final_state = res; - - state_list_append (res); - return res; -} - - -/*--------------------------------------------------------------. -| Find the state number for the state we would get to (from the | -| current state) by shifting symbol. Create a new state if no | -| equivalent one exists already. Used by append_states. | -`--------------------------------------------------------------*/ - -static state_number_t get_state (symbol_number_t symbol, size_t core_size, item_number_t *core) { state_t *sp; - if (trace_flag) + if (trace_flag & trace_automaton) fprintf (stderr, "Entering get_state, symbol = %d (%s)\n", symbol, symbols[symbol]->tag); sp = state_hash_lookup (core_size, core); if (!sp) - sp = new_state (symbol, core_size, core); + sp = state_list_append (symbol, core_size, core); - if (trace_flag) + if (trace_flag & trace_automaton) fprintf (stderr, "Exiting get_state => %d\n", sp->number); - return sp->number; + return sp; } -/*------------------------------------------------------------------. -| Use the information computed by new_itemsets to find the state | -| numbers reached by each shift transition from STATE. | -| | -| TRANSITIONSET is set up as a vector of state numbers of those states. | -`------------------------------------------------------------------*/ +/*---------------------------------------------------------------. +| Use the information computed by new_itemsets to find the state | +| numbers reached by each shift transition from STATE. | +| | +| SHIFTSET is set up as a vector of those states. | +`---------------------------------------------------------------*/ static void append_states (state_t *state) @@ -250,7 +245,7 @@ append_states (state_t *state) int j; symbol_number_t symbol; - if (trace_flag) + if (trace_flag & trace_automaton) fprintf (stderr, "Entering append_states, state = %d\n", state->number); @@ -277,17 +272,6 @@ append_states (state_t *state) } -static void -new_states (void) -{ - /* The 0 at the lhs is the index of the item of this initial rule. */ - kernel_base[0][0] = 0; - kernel_size[0] = 1; - state_list_append (new_state (0, kernel_size[0], kernel_base[0])); -} - - - /*----------------------------------------------------------------. | Find which rules can be used for reduction transitions from the | | current state and make a reductions structure for the state to | @@ -300,17 +284,12 @@ save_reductions (state_t *state) int count = 0; int i; - /* If this is the final state, we want it to have no reductions at - all, although it has one for `START_SYMBOL EOF .'. */ - if (final_state && state->number == final_state->number) - return; - /* Find and count the active items that represent ends of rules. */ for (i = 0; i < nritemset; ++i) { int item = ritem[itemset[i]]; if (item < 0) - redset[count++] = -item; + redset[count++] = &rules[item_number_as_rule_number (item)]; } /* Make a reductions structure and copy the data into it. */ @@ -332,13 +311,12 @@ set_states (void) state_list_t *this = first_state; /* Pessimization, but simplification of the code: make sure all - the states have a shifts, errs, and reductions, even if - reduced to 0. */ + the states have valid transitions and reductions members, + even if reduced to 0. It is too soon for errs, which are + computed later, but set_conflicts. */ state_t *state = this->state; - if (!state->shifts) + if (!state->transitions) state_transitions_set (state, 0, 0); - if (!state->errs) - state->errs = errs_new (0); if (!state->reductions) state_reductions_set (state, 0, 0); @@ -363,13 +341,19 @@ generate_states (void) state_list_t *list = NULL; allocate_storage (); new_closure (nritems); - new_states (); + + /* Create the initial state. The 0 at the lhs is the index of the + item of this initial rule. */ + kernel_base[0][0] = 0; + kernel_size[0] = 1; + state_list_append (0, kernel_size[0], kernel_base[0]); + list = first_state; while (list) { state_t *state = list->state; - if (trace_flag) + if (trace_flag & trace_automaton) fprintf (stderr, "Processing state %d (reached by %s)\n", state->number, symbols[state->accessing_symbol]->tag);