X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/6a164e0c9619066b9d3f9e2401f68b602d4159e1..975553805cf2a8e906fee420c0e0bf4945935d63:/src/LR0.c diff --git a/src/LR0.c b/src/LR0.c index ccd55f6a..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 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. @@ -23,6 +25,10 @@ The entry point is generate_states. */ #include "system.h" +#include "bitset.h" +#include "quotearg.h" +#include "symtab.h" +#include "gram.h" #include "getargs.h" #include "reader.h" #include "gram.h" @@ -33,35 +39,66 @@ #include "lalr.h" #include "reduce.h" -int nstates; -int final_state; -static state_t *first_state = NULL; -static shifts *first_shift = NULL; +typedef struct state_list_s +{ + struct state_list_s *next; + state_t *state; +} state_list_t; -static state_t *this_state = NULL; -static state_t *last_state = NULL; -static shifts *last_shift = NULL; +static state_list_t *first_state = NULL; +static state_list_t *last_state = NULL; -static int nshifts; -static short *shift_symbol = NULL; -static short *redset = NULL; -static short *shiftset = NULL; +/*------------------------------------------------------------------. +| A state was just discovered from another state. Queue it for | +| later examination, in order to find its transitions. Return it. | +`------------------------------------------------------------------*/ -static short **kernel_base = NULL; -static int *kernel_size = NULL; -static short *kernel_items = NULL; +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); -/* hash table for states, to recognize equivalent ones. */ + if (trace_flag & trace_automaton) + fprintf (stderr, "state_list_append (state = %d, symbol = %d (%s))\n", + nstates, symbol, symbols[symbol]->tag); -#define STATE_HASH_SIZE 1009 -static state_t **state_hash = NULL; + /* 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; + + if (!first_state) + first_state = node; + if (last_state) + last_state->next = node; + last_state = node; + + return state; +} + +static int nshifts; +static symbol_number_t *shift_symbol = NULL; + +static rule_t **redset = NULL; +static state_t **shiftset = NULL; + +static item_number_t **kernel_base = NULL; +static int *kernel_size = NULL; +static item_number_t *kernel_items = NULL; static void allocate_itemsets (void) { - int i; + symbol_number_t i; + rule_number_t r; + item_number_t *rhsp; /* Count the number of occurrences of all the symbols in RITEMS. Note that useless productions (hence useless nonterminals) are @@ -70,22 +107,22 @@ allocate_itemsets (void) int count = 0; short *symbol_count = XCALLOC (short, nsyms + nuseless_nonterminals); - for (i = 0; ritem[i]; ++i) - if (ritem[i] > 0) + for (r = 0; r < nrules; ++r) + for (rhsp = rules[r].rhs; *rhsp >= 0; ++rhsp) { count++; - symbol_count[ritem[i]]++; + symbol_count[*rhsp]++; } /* See comments before new_itemsets. All the vectors of items live inside KERNEL_ITEMS. The number of active items after some symbol cannot be more than the number of times that symbol - appears as an item, which is symbol_count[symbol]. + appears as an item, which is SYMBOL_COUNT[SYMBOL]. We allocate that much space for each symbol. */ - kernel_base = XCALLOC (short *, nsyms); + kernel_base = XCALLOC (item_number_t *, nsyms); if (count) - kernel_items = XCALLOC (short, count); + kernel_items = XCALLOC (item_number_t, count); count = 0; for (i = 0; i < nsyms; i++) @@ -104,9 +141,10 @@ allocate_storage (void) { allocate_itemsets (); - shiftset = XCALLOC (short, nsyms); - redset = XCALLOC (short, nrules + 1); - state_hash = XCALLOC (state_t *, STATE_HASH_SIZE); + shiftset = XCALLOC (state_t *, nsyms); + redset = XCALLOC (rule_t *, nrules); + state_hash_new (); + shift_symbol = XCALLOC (symbol_number_t, nsyms); } @@ -119,169 +157,97 @@ free_storage (void) free (kernel_base); free (kernel_size); XFREE (kernel_items); - free (state_hash); + state_hash_free (); } -/*----------------------------------------------------------------. -| Find which symbols can be shifted in the current state, and for | -| each one record which items would be active after that shift. | -| Uses the contents of itemset. | -| | -| shift_symbol is set to a vector of the symbols that can be | -| shifted. For each symbol in the grammar, kernel_base[symbol] | -| points to a vector of item numbers activated if that symbol is | -| shifted, and kernel_size[symbol] is their numbers. | -`----------------------------------------------------------------*/ +/*---------------------------------------------------------------. +| Find which symbols can be shifted in STATE, and for each one | +| record which items would be active after that shift. Uses the | +| contents of itemset. | +| | +| shift_symbol is set to a vector of the symbols that can be | +| shifted. For each symbol in the grammar, kernel_base[symbol] | +| points to a vector of item numbers activated if that symbol is | +| shifted, and kernel_size[symbol] is their numbers. | +`---------------------------------------------------------------*/ static void -new_itemsets (void) +new_itemsets (state_t *state) { int i; - if (trace_flag) + if (trace_flag & trace_automaton) fprintf (stderr, "Entering new_itemsets, state = %d\n", - this_state->number); + state->number); for (i = 0; i < nsyms; i++) kernel_size[i] = 0; - shift_symbol = XCALLOC (short, nsyms); nshifts = 0; - for (i = 0; i < nitemset; ++i) - { - int symbol = ritem[itemset[i]]; - if (symbol > 0) - { - if (!kernel_size[symbol]) - { - shift_symbol[nshifts] = symbol; - nshifts++; - } - - kernel_base[symbol][kernel_size[symbol]] = itemset[i] + 1; - kernel_size[symbol]++; - } - } + for (i = 0; i < nritemset; ++i) + if (ritem[itemset[i]] >= 0) + { + symbol_number_t symbol + = item_number_as_symbol_number (ritem[itemset[i]]); + if (!kernel_size[symbol]) + { + shift_symbol[nshifts] = symbol; + nshifts++; + } + + kernel_base[symbol][kernel_size[symbol]] = itemset[i] + 1; + kernel_size[symbol]++; + } } /*-----------------------------------------------------------------. -| 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 (int symbol) -{ - state_t *p; - - if (trace_flag) - fprintf (stderr, "Entering new_state, state = %d, symbol = %d (%s)\n", - this_state->number, symbol, tags[symbol]); - - if (nstates >= MAXSHORT) - fatal (_("too many states (max %d)"), MAXSHORT); - - p = STATE_ALLOC (kernel_size[symbol]); - p->accessing_symbol = symbol; - p->number = nstates; - p->nitems = kernel_size[symbol]; - - shortcpy (p->items, kernel_base[symbol], kernel_size[symbol]); - - last_state->next = p; - last_state = p; - nstates++; - - return p; -} - - -/*--------------------------------------------------------------. -| 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 int -get_state (int symbol) +get_state (symbol_number_t symbol, size_t core_size, item_number_t *core) { - int key; - int i; state_t *sp; - if (trace_flag) - fprintf (stderr, "Entering get_state, state = %d, symbol = %d (%s)\n", - this_state->number, symbol, tags[symbol]); + if (trace_flag & trace_automaton) + fprintf (stderr, "Entering get_state, symbol = %d (%s)\n", + symbol, symbols[symbol]->tag); - /* Add up the target state's active item numbers to get a hash key. - */ - key = 0; - for (i = 0; i < kernel_size[symbol]; ++i) - key += kernel_base[symbol][i]; - key = key % STATE_HASH_SIZE; - sp = state_hash[key]; + sp = state_hash_lookup (core_size, core); + if (!sp) + sp = state_list_append (symbol, core_size, core); - if (sp) - { - int found = 0; - while (!found) - { - if (sp->nitems == kernel_size[symbol]) - { - found = 1; - for (i = 0; i < kernel_size[symbol]; ++i) - if (kernel_base[symbol][i] != sp->items[i]) - found = 0; - } - - if (!found) - { - if (sp->link) - { - sp = sp->link; - } - else /* bucket exhausted and no match */ - { - sp = sp->link = new_state (symbol); - found = 1; - } - } - } - } - else /* bucket is empty */ - { - state_hash[key] = sp = new_state (symbol); - } - - 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 the current state. | -| | -| shiftset 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 (void) +append_states (state_t *state) { int i; int j; - int symbol; + symbol_number_t symbol; - if (trace_flag) + if (trace_flag & trace_automaton) fprintf (stderr, "Entering append_states, state = %d\n", - this_state->number); + state->number); /* first sort shift_symbol into increasing order */ @@ -298,271 +264,11 @@ append_states (void) } for (i = 0; i < nshifts; i++) - shiftset[i] = get_state (shift_symbol[i]); -} - - -static void -new_states (void) -{ - first_state = last_state = this_state = STATE_ALLOC (0); - nstates = 1; -} - - -/*------------------------------------------------------------. -| Save the NSHIFTS of SHIFTSET into the current linked list. | -`------------------------------------------------------------*/ - -static void -save_shifts (void) -{ - shifts *p = shifts_new (nshifts); - - p->number = this_state->number; - shortcpy (p->shifts, shiftset, nshifts); - this_state->shifts = p; - - if (last_shift) - last_shift->next = p; - else - first_shift = p; - last_shift = p; -} - - -/*------------------------------------------------------------------. -| Subroutine of augment_automaton. Create the next-to-final state, | -| to which a shift has already been made in the initial state. | -| | -| The task of this state consists in shifting (actually, it's a | -| goto, but shifts and gotos are both stored in SHIFTS) the start | -| symbols, hence the name. | -`------------------------------------------------------------------*/ - -static void -insert_start_shifting_state (void) -{ - state_t *statep; - shifts *sp; - - statep = STATE_ALLOC (0); - statep->number = nstates; - - /* The distinctive feature of this state from the - eof_shifting_state, is that it is labeled as post-start-symbol - shifting. I fail to understand why this state, and the - post-start-start can't be merged into one. But it does fail if - you try. --akim */ - statep->accessing_symbol = start_symbol; - - last_state->next = statep; - last_state = statep; - - /* Make a shift from this state to (what will be) the final state. */ - sp = shifts_new (1); - statep->shifts = sp; - sp->number = nstates++; - sp->shifts[0] = nstates; - - last_shift->next = sp; - last_shift = sp; -} - - -/*-----------------------------------------------------------------. -| Subroutine of augment_automaton. Create the final state, which | -| shifts `0', the end of file. The initial state shifts the start | -| symbol, and goes to here. | -`-----------------------------------------------------------------*/ - -static void -insert_eof_shifting_state (void) -{ - state_t *statep; - shifts *sp; - - /* Make the final state--the one that follows a shift from the - next-to-final state. - The symbol for that shift is 0 (end-of-file). */ - statep = STATE_ALLOC (0); - statep->number = nstates; - - last_state->next = statep; - last_state = statep; - - /* Make the shift from the final state to the termination state. */ - sp = shifts_new (1); - statep->shifts = sp; - sp->number = nstates++; - sp->shifts[0] = nstates; - - last_shift->next = sp; - last_shift = sp; -} - - -/*---------------------------------------------------------------. -| Subroutine of augment_automaton. Create the accepting state. | -`---------------------------------------------------------------*/ - -static void -insert_accepting_state (void) -{ - state_t *statep; - - /* Note that the variable `final_state' refers to what we sometimes - call the termination state. */ - final_state = nstates; - - /* Make the termination state. */ - statep = STATE_ALLOC (0); - statep->number = nstates++; - last_state->next = statep; - last_state = statep; -} - - - - - -/*------------------------------------------------------------------. -| Make sure that the initial state has a shift that accepts the | -| grammar's start symbol and goes to the next-to-final state, which | -| has a shift going to the final state, which has a shift to the | -| termination state. Create such states and shifts if they don't | -| happen to exist already. | -`------------------------------------------------------------------*/ - -static void -augment_automaton (void) -{ - if (!first_shift->nshifts) - { - /* There are no shifts for any state. Make one shift, from the - initial state to the next-to-final state. */ - - shifts *sp = shifts_new (1); - first_state->shifts = sp; - sp->shifts[0] = nstates; - - /* Initialize the chain of shifts with sp. */ - first_shift = sp; - last_shift = sp; - - /* Create the next-to-final state, with shift to - what will be the final state. */ - insert_start_shifting_state (); - } - else if (first_shift->number == 0) { - state_t *statep = first_state->next; - shifts *sp = first_shift; - shifts *sp1 = NULL; - /* The states reached by shifts from FIRST_STATE are numbered - 1..(SP->NSHIFTS). Look for one reached by START_SYMBOL. */ - while (statep->accessing_symbol != start_symbol - && statep->number < sp->nshifts) - statep = statep->next; - - if (statep->accessing_symbol == start_symbol) - { - /* We already have a next-to-final state. - Make sure it has a shift to what will be the final state. */ - while (sp && sp->number < statep->number) - { - sp1 = sp; - sp = sp->next; - } - - if (sp && sp->number == statep->number) - { - int i; - shifts *sp2 = shifts_new (sp->nshifts + 1); - sp2->number = statep->number; - statep->shifts = sp2; - sp2->shifts[0] = nstates; - for (i = sp->nshifts; i > 0; i--) - sp2->shifts[i] = sp->shifts[i - 1]; - - /* Patch sp2 into the chain of shifts in place of sp, - following sp1. */ - sp2->next = sp->next; - sp1->next = sp2; - if (sp == last_shift) - last_shift = sp2; - XFREE (sp); - } - else - { - shifts *sp2 = shifts_new (1); - sp2->number = statep->number; - statep->shifts = sp2; - sp2->shifts[0] = nstates; - - /* Patch sp2 into the chain of shifts between sp1 and sp. */ - sp2->next = sp; - sp1->next = sp2; - if (sp == 0) - last_shift = sp2; - } - } - else - { - int i, k; - shifts *sp2; - sp = first_shift; - - /* There is no next-to-final state as yet. */ - /* Add one more shift in first_shift, - going to the next-to-final state (yet to be made). */ - sp2 = shifts_new (sp->nshifts + 1); - first_state->shifts = sp2; - /* Stick this shift into the vector at the proper place. */ - statep = first_state->next; - for (k = 0, i = 0; i < sp->nshifts; k++, i++) - { - if (statep->accessing_symbol > start_symbol && i == k) - sp2->shifts[k++] = nstates; - sp2->shifts[k] = sp->shifts[i]; - statep = statep->next; - } - if (i == k) - sp2->shifts[k++] = nstates; - - /* Patch sp2 into the chain of shifts - in place of sp, at the beginning. */ - sp2->next = sp->next; - first_shift = sp2; - if (last_shift == sp) - last_shift = sp2; - - XFREE (sp); - - /* Create the next-to-final state, with shift to - what will be the final state. */ - insert_start_shifting_state (); - } - } - else - { - /* The initial state didn't even have any shifts. - Give it one shift, to the next-to-final state. */ - shifts *sp = shifts_new (1); - first_state->shifts = sp; - sp->shifts[0] = nstates; - - /* Patch sp into the chain of shifts at the beginning. */ - sp->next = first_shift; - first_shift = sp; - - /* Create the next-to-final state, with shift to - what will be the final state. */ - insert_start_shifting_state (); + symbol = shift_symbol[i]; + shiftset[i] = get_state (symbol, + kernel_size[symbol], kernel_base[symbol]); } - - insert_eof_shifting_state (); - insert_accepting_state (); } @@ -573,95 +279,57 @@ augment_automaton (void) `----------------------------------------------------------------*/ static void -save_reductions (void) +save_reductions (state_t *state) { - int count; + int count = 0; int i; /* Find and count the active items that represent ends of rules. */ - - count = 0; - for (i = 0; i < nitemset; ++i) + 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. */ - - if (count) - { - reductions *p = REDUCTIONS_ALLOC (count); - p->nreds = count; - shortcpy (p->rules, redset, count); - - this_state->reductions = p; - } + state_reductions_set (state, count, redset); } -/*--------------------. -| Build STATE_TABLE. | -`--------------------*/ +/*---------------. +| Build STATES. | +`---------------*/ static void -set_state_table (void) +set_states (void) { - /* NSTATES + 1 because lookahead for the pseudo state number NSTATES - might be used (see conflicts.c). It is too opaque for me to - provide a probably less hacky implementation. --akim */ - state_table = XCALLOC (state_t *, nstates + 1); - - { - state_t *sp; - for (sp = first_state; sp; sp = sp->next) - state_table[sp->number] = sp; - } - - /* Pessimization, but simplification of the code: make sure all the - states have a shifts, even if reduced to 0 shifts. */ - { - int i; - for (i = 0; i < nstates; i++) - if (!state_table[i]->shifts) - state_table[i]->shifts = shifts_new (0); - } - - /* Initializing the lookaheads members. Please note that it must be - performed after having set some of the other members which are - used below. Change with extreme caution. */ - { - int i; - int count = 0; - for (i = 0; i < nstates; i++) - { - int k; - reductions *rp = state_table[i]->reductions; - shifts *sp = state_table[i]->shifts; - - state_table[i]->lookaheads = count; - - if (rp - && (rp->nreds > 1 || (sp->nshifts && SHIFT_IS_SHIFT (sp, 0)))) - count += rp->nreds; - else - state_table[i]->consistent = 1; - - for (k = 0; k < sp->nshifts; k++) - if (SHIFT_IS_ERROR (sp, k)) - { - state_table[i]->consistent = 0; - break; - } - } + states = XCALLOC (state_t *, nstates); - /* Seems to be needed by conflicts.c. */ - state_table[nstates] = STATE_ALLOC (0); - state_table[nstates]->lookaheads = count; - } + while (first_state) + { + state_list_t *this = first_state; + + /* Pessimization, but simplification of the code: make sure all + 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->transitions) + state_transitions_set (state, 0, 0); + if (!state->reductions) + state_reductions_set (state, 0, 0); + + states[state->number] = state; + + first_state = this->next; + free (this); + } + first_state = NULL; + last_state = NULL; } + /*-------------------------------------------------------------------. | Compute the nondeterministic finite state machine (see state.h for | | details) from the grammar. | @@ -670,42 +338,50 @@ set_state_table (void) void generate_states (void) { + state_list_t *list = NULL; allocate_storage (); - new_closure (nitems); - new_states (); + new_closure (nritems); + + /* 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]); - while (this_state) + list = first_state; + + while (list) { - if (trace_flag) + state_t *state = list->state; + if (trace_flag & trace_automaton) fprintf (stderr, "Processing state %d (reached by %s)\n", - this_state->number, tags[this_state->accessing_symbol]); + state->number, + symbols[state->accessing_symbol]->tag); /* Set up ruleset and itemset for the transitions out of this state. ruleset gets a 1 bit for each rule that could reduce now. itemset gets a vector of all the items that could be accepted next. */ - closure (this_state->items, this_state->nitems); - /* record the reductions allowed out of this state */ - save_reductions (); - /* find the itemsets of the states that shifts can reach */ - new_itemsets (); - /* find or create the core structures for those states */ - append_states (); - - /* create the shifts structures for the shifts to those states, - now that the state numbers transitioning to are known */ - save_shifts (); - - /* states are queued when they are created; process them all */ - this_state = this_state->next; + closure (state->items, state->nitems); + /* Record the reductions allowed out of this state. */ + save_reductions (state); + /* Find the itemsets of the states that shifts can reach. */ + new_itemsets (state); + /* Find or create the core structures for those states. */ + append_states (state); + + /* Create the shifts structures for the shifts to those states, + now that the state numbers transitioning to are known. */ + state_transitions_set (state, nshifts, shiftset); + + /* States are queued when they are created; process them all. + */ + list = list->next; } /* discard various storage */ free_closure (); free_storage (); - /* set up initial and final states as parser wants them */ - augment_automaton (); - - /* Set up STATE_TABLE. */ - set_state_table (); + /* Set up STATES. */ + set_states (); }