X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/97db7bd4a13ca29874bc0691446b8267f256e634..f939fc12fea8a86862698dd07ff4d972ed99083d:/src/LR0.c?ds=sidebyside diff --git a/src/LR0.c b/src/LR0.c index d1d703ff..ae39b7ce 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. +/* Generate the nondeterministic finite state machine for Bison. + + Copyright (C) 1984, 1986, 1989, 2000, 2001, 2002 Free Software + Foundation, Inc. This file is part of Bison, the GNU Compiler Compiler. @@ -23,73 +25,105 @@ The entry point is generate_states. */ #include "system.h" + +#include +#include + +#include "LR0.h" +#include "closure.h" +#include "complain.h" +#include "getargs.h" #include "gram.h" +#include "gram.h" +#include "lalr.h" +#include "reader.h" +#include "reduce.h" #include "state.h" -#include "complain.h" -#include "closure.h" -#include "LR0.h" +#include "symtab.h" +typedef struct state_list +{ + struct state_list *next; + state *state; +} state_list; -int nstates; -int final_state; -core *first_state = NULL; -shifts *first_shift = NULL; -reductions *first_reduction = NULL; +static state_list *first_state = NULL; +static state_list *last_state = NULL; -static core *this_state = NULL; -static core *last_state = NULL; -static shifts *last_shift = NULL; -static reductions *last_reduction = NULL; -static int nshifts; -static short *shift_symbol = NULL; +/*------------------------------------------------------------------. +| A state was just discovered from another state. Queue it for | +| later examination, in order to find its transitions. Return it. | +`------------------------------------------------------------------*/ -static short *redset = NULL; -static short *shiftset = NULL; +static state * +state_list_append (symbol_number sym, size_t core_size, item_number *core) +{ + state_list *node = MALLOC (node, 1); + state *s = state_new (sym, core_size, core); -static short **kernel_base = NULL; -static short **kernel_end = NULL; -static short *kernel_items = NULL; + if (trace_flag & trace_automaton) + fprintf (stderr, "state_list_append (state = %d, symbol = %d (%s))\n", + nstates, sym, symbols[sym]->tag); -/* hash table for states, to recognize equivalent ones. */ + /* If this is the endtoken, and this is not the initial state, then + this is the final state. */ + if (sym == 0 && first_state) + final_state = s; -#define STATE_TABLE_SIZE 1009 -static core **state_table = NULL; + node->next = NULL; + node->state = s; + + if (!first_state) + first_state = node; + if (last_state) + last_state->next = node; + last_state = node; + + return s; +} + +static int nshifts; +static symbol_number *shift_symbol = NULL; + +static rule **redset = NULL; +static state **shiftset = NULL; + +static item_number **kernel_base = NULL; +static int *kernel_size = NULL; +static item_number *kernel_items = NULL; static void allocate_itemsets (void) { - short *itemp = NULL; - int symbol; - int i; - int count; - short *symbol_count = NULL; - - count = 0; - symbol_count = XCALLOC (short, nsyms); - - itemp = ritem; - symbol = *itemp++; - while (symbol) - { - if (symbol > 0) - { - count++; - symbol_count[symbol]++; - } - symbol = *itemp++; - } + symbol_number i; + rule_number r; + item_number *rhsp; + + /* Count the number of occurrences of all the symbols in RITEMS. + Note that useless productions (hence useless nonterminals) are + browsed too, hence we need to allocate room for _all_ the + symbols. */ + int count = 0; + short *symbol_count = CALLOC (symbol_count, nsyms + nuseless_nonterminals); + + for (r = 0; r < nrules; ++r) + for (rhsp = rules[r].rhs; *rhsp >= 0; ++rhsp) + { + count++; + 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]. + some symbol S cannot be more than the number of times that S + appears as an item, which is SYMBOL_COUNT[S]. We allocate that much space for each symbol. */ - kernel_base = XCALLOC (short *, nsyms); + CALLOC (kernel_base, nsyms); if (count) - kernel_items = XCALLOC (short, count); + CALLOC (kernel_items, count); count = 0; for (i = 0; i < nsyms; i++) @@ -98,8 +132,8 @@ allocate_itemsets (void) count += symbol_count[i]; } - shift_symbol = symbol_count; - kernel_end = XCALLOC (short *, nsyms); + free (symbol_count); + CALLOC (kernel_size, nsyms); } @@ -108,444 +142,125 @@ allocate_storage (void) { allocate_itemsets (); - shiftset = XCALLOC (short, nsyms); - redset = XCALLOC (short, nrules + 1); - state_table = XCALLOC (core *, STATE_TABLE_SIZE); + CALLOC (shiftset, nsyms); + CALLOC (redset, nrules); + state_hash_new (); + CALLOC (shift_symbol, nsyms); } static void free_storage (void) { - XFREE (shift_symbol); - XFREE (redset); - XFREE (shiftset); - XFREE (kernel_base); - XFREE (kernel_end); + free (shift_symbol); + free (redset); + free (shiftset); + free (kernel_base); + free (kernel_size); XFREE (kernel_items); - XFREE (state_table); + 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_end[symbol] points after the end of that | -| vector. | -`----------------------------------------------------------------*/ +/*---------------------------------------------------------------. +| Find which symbols can be shifted in S, 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 *s) { int i; - int shiftcount; -#if TRACE - fprintf (stderr, "Entering new_itemsets, state = %d\n", - this_state->number); -#endif + if (trace_flag & trace_automaton) + fprintf (stderr, "Entering new_itemsets, state = %d\n", s->number); for (i = 0; i < nsyms; i++) - kernel_end[i] = NULL; - - shiftcount = 0; - - for (i = 0; i < itemsetend - itemset; ++i) - { - int symbol = ritem[itemset[i]]; - if (symbol > 0) - { - short *ksp = kernel_end[symbol]; - - if (!ksp) - { - shift_symbol[shiftcount] = symbol; - ksp = kernel_base[symbol]; - shiftcount++; - } - - *ksp++ = itemset[i] + 1; - kernel_end[symbol] = ksp; - } - } - - nshifts = shiftcount; + kernel_size[i] = 0; + + nshifts = 0; + + for (i = 0; i < nritemset; ++i) + if (ritem[itemset[i]] >= 0) + { + symbol_number sym = item_number_as_symbol_number (ritem[itemset[i]]); + if (!kernel_size[sym]) + { + shift_symbol[nshifts] = sym; + nshifts++; + } + + kernel_base[sym][kernel_size[sym]] = itemset[i] + 1; + kernel_size[sym]++; + } } -/*-----------------------------------------------------------------. -| Subroutine of get_state. Create a new state for those items, if | -| necessary. | -`-----------------------------------------------------------------*/ - -static core * -new_state (int symbol) -{ - int n; - core *p; - -#if TRACE - fprintf (stderr, "Entering new_state, state = %d, symbol = %d\n", - nstates, symbol); -#endif - - if (nstates >= MAXSHORT) - fatal (_("too many states (max %d)"), MAXSHORT); - - n = kernel_end[symbol] - kernel_base[symbol]; - - p = CORE_ALLOC (n); - p->accessing_symbol = symbol; - p->number = nstates; - p->nitems = n; - - shortcpy (p->items, kernel_base[symbol], n); - - 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. | +| Find the state we would get to (from the current state) by | +| shifting SYM. Create a new state if no equivalent one exists | +| already. Used by append_states. | `--------------------------------------------------------------*/ -static int -get_state (int symbol) +static state * +get_state (symbol_number sym, size_t core_size, item_number *core) { - int key; - short *isp2; - int i; - core *sp; - - int n = kernel_end[symbol] - kernel_base[symbol]; + state *sp; -#if TRACE - fprintf (stderr, "Entering get_state, state = %d, symbol = %d\n", - nstates, symbol); -#endif + if (trace_flag & trace_automaton) + fprintf (stderr, "Entering get_state, symbol = %d (%s)\n", + sym, symbols[sym]->tag); - /* Add up the target state's active item numbers to get a hash key. - */ - key = 0; - for (i = 0; i < n; ++i) - key += kernel_base[symbol][i]; - key = key % STATE_TABLE_SIZE; - sp = state_table[key]; + sp = state_hash_lookup (core_size, core); + if (!sp) + sp = state_list_append (sym, core_size, core); - if (sp) - { - int found = 0; - while (!found) - { - if (sp->nitems == n) - { - int i; - found = 1; - for (i = 0; i < n; ++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_table[key] = sp = new_state (symbol); - } + 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 S. | +| | +| SHIFTSET is set up as a vector of those states. | +`---------------------------------------------------------------*/ static void -append_states (void) +append_states (state *s) { int i; - int j; - int symbol; -#if TRACE - fprintf (stderr, "Entering append_states\n"); -#endif + if (trace_flag & trace_automaton) + fprintf (stderr, "Entering append_states, state = %d\n", s->number); - /* first sort shift_symbol into increasing order */ + /* First sort shift_symbol into increasing order. */ for (i = 1; i < nshifts; i++) { - symbol = shift_symbol[i]; - j = i; - while (j > 0 && shift_symbol[j - 1] > symbol) - { - shift_symbol[j] = shift_symbol[j - 1]; - j--; - } - shift_symbol[j] = symbol; + symbol_number sym = shift_symbol[i]; + int j; + for (j = i; 0 < j && sym < shift_symbol [j - 1]; j--) + shift_symbol[j] = shift_symbol[j - 1]; + shift_symbol[j] = sym; } for (i = 0; i < nshifts; i++) - shiftset[i] = get_state (shift_symbol[i]); -} - - -static void -new_states (void) -{ - first_state = last_state = this_state = CORE_ALLOC (0); - nstates = 1; -} - - -static void -save_shifts (void) -{ - shifts *p = SHIFTS_ALLOC (nshifts); - - p->number = this_state->number; - p->nshifts = nshifts; - - shortcpy (p->shifts, shiftset, nshifts); - - 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. | -`------------------------------------------------------------------*/ - -static void -insert_start_shift (void) -{ - core *statep; - shifts *sp; - - statep = CORE_ALLOC (0); - statep->number = nstates; - 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_ALLOC (1); - sp->number = nstates++; - sp->nshifts = 1; - sp->shifts[0] = nstates; - - last_shift->next = sp; - last_shift = sp; -} - - -/*------------------------------------------------------------------. -| 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) -{ - int i; - int k; - core *statep; - shifts *sp; - shifts *sp2; - shifts *sp1 = NULL; - - sp = first_shift; - - if (sp) - { - if (sp->number == 0) - { - k = sp->nshifts; - statep = first_state->next; - - /* The states reached by shifts from first_state are numbered 1...K. - Look for one reached by start_symbol. */ - while (statep->accessing_symbol < start_symbol - && statep->number < k) - 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. */ - k = statep->number; - - while (sp && sp->number < k) - { - sp1 = sp; - sp = sp->next; - } - - if (sp && sp->number == k) - { - sp2 = SHIFTS_ALLOC (sp->nshifts + 1); - sp2->number = k; - sp2->nshifts = sp->nshifts + 1; - 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 - { - sp2 = SHIFTS_ALLOC (1); - sp2->number = k; - sp2->nshifts = 1; - 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 - { - /* 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). */ - sp = first_shift; - - sp2 = SHIFTS_ALLOC (sp->nshifts + 1); - sp2->nshifts = sp->nshifts + 1; - - /* 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_shift (); - } - } - else - { - /* The initial state didn't even have any shifts. - Give it one shift, to the next-to-final state. */ - sp = SHIFTS_ALLOC (1); - sp->nshifts = 1; - 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_shift (); - } - } - else { - /* There are no shifts for any state. - Make one shift, from the initial state to the next-to-final state. */ - - sp = SHIFTS_ALLOC (1); - sp->nshifts = 1; - 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_shift (); + symbol_number sym = shift_symbol[i]; + shiftset[i] = get_state (sym, kernel_size[sym], kernel_base[sym]); } - - /* 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 = CORE_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_ALLOC (1); - sp->number = nstates++; - sp->nshifts = 1; - sp->shifts[0] = nstates; - last_shift->next = sp; - last_shift = sp; - - /* Note that the variable `final_state' refers to what we sometimes call - the termination state. */ - final_state = nstates; - - /* Make the termination state. */ - statep = CORE_ALLOC (0); - statep->number = nstates++; - last_state->next = statep; - last_state = statep; } @@ -556,45 +271,57 @@ augment_automaton (void) `----------------------------------------------------------------*/ static void -save_reductions (void) +save_reductions (state *s) { - short *isp; - int item; - int count; - reductions *p; - - short *rend; + int count = 0; + int i; /* Find and count the active items that represent ends of rules. */ - - count = 0; - for (isp = itemset; isp < itemsetend; isp++) + for (i = 0; i < nritemset; ++i) { - item = ritem[*isp]; + 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. */ + state_reductions_set (s, count, redset); +} - if (count) - { - p = REDUCTIONS_ALLOC (count); - - p->number = this_state->number; - p->nreds = count; + +/*---------------. +| Build STATES. | +`---------------*/ - shortcpy (p->rules, redset, count); +static void +set_states (void) +{ + CALLOC (states, nstates); - if (last_reduction) - last_reduction->next = p; - else - first_reduction = p; - last_reduction = p; + while (first_state) + { + state_list *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 *s = this->state; + if (!s->transitions) + state_transitions_set (s, 0, 0); + if (!s->reductions) + state_reductions_set (s, 0, 0); + + states[s->number] = s; + + 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. | @@ -603,37 +330,50 @@ save_reductions (void) void generate_states (void) { + state_list *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]); + + list = first_state; - while (this_state) + while (list) { + state *s = list->state; + if (trace_flag & trace_automaton) + fprintf (stderr, "Processing state %d (reached by %s)\n", + s->number, + symbols[s->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 */ - if (nshifts > 0) - save_shifts (); - - /* states are queued when they are created; process them all */ - this_state = this_state->next; + closure (s->items, s->nitems); + /* Record the reductions allowed out of this state. */ + save_reductions (s); + /* Find the itemsets of the states that shifts can reach. */ + new_itemsets (s); + /* Find or create the core structures for those states. */ + append_states (s); + + /* Create the shifts structures for the shifts to those states, + now that the state numbers transitioning to are known. */ + state_transitions_set (s, 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 STATES. */ + set_states (); }