X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/300f275f23b65c09f69a437c635c48ddd126f21a..616429b50868bf9225d55143526442a024e32969:/src/LR0.c?ds=sidebyside diff --git a/src/LR0.c b/src/LR0.c index db42fe30..6a911f24 100644 --- a/src/LR0.c +++ b/src/LR0.c @@ -1,5 +1,5 @@ /* Generate the nondeterministic finite state machine for bison, - Copyright 1984, 1986, 1989, 2000 Free Software Foundation, Inc. + Copyright 1984, 1986, 1989, 2000, 2001 Free Software Foundation, Inc. This file is part of Bison, the GNU Compiler Compiler. @@ -23,23 +23,30 @@ The entry point is generate_states. */ #include "system.h" +#include "symtab.h" +#include "getargs.h" +#include "reader.h" #include "gram.h" #include "state.h" #include "complain.h" #include "closure.h" #include "LR0.h" - +#include "lalr.h" +#include "reduce.h" int nstates; -int final_state; -core *first_state = NULL; -shifts *first_shift = NULL; -reductions *first_reduction = NULL; +/* Initialize the final state to -1, otherwise, it might be set to 0 + by default, and since we don't compute the reductions of the final + state, we end up not computing the reductions of the initial state, + which is of course needed. + + FINAL_STATE is properly set by new_state when it recognizes the + accessing symbol: EOF. */ +int final_state = -1; +static state_t *first_state = NULL; -static core *this_state = NULL; -static core *last_state = NULL; -static shifts *last_shift = NULL; -static reductions *last_reduction = NULL; +static state_t *this_state = NULL; +static state_t *last_state = NULL; static int nshifts; static short *shift_symbol = NULL; @@ -48,38 +55,33 @@ static short *redset = NULL; static short *shiftset = NULL; static short **kernel_base = NULL; -static short **kernel_end = NULL; +static int *kernel_size = NULL; static short *kernel_items = NULL; /* hash table for states, to recognize equivalent ones. */ -#define STATE_TABLE_SIZE 1009 -static core **state_table = NULL; +#define STATE_HASH_SIZE 1009 +static state_t **state_hash = 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); + /* 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 = XCALLOC (short, nsyms + nuseless_nonterminals); - itemp = ritem; - symbol = *itemp++; - while (symbol) - { - if (symbol > 0) - { - count++; - symbol_count[symbol]++; - } - symbol = *itemp++; - } + for (i = 0; i < nritems; ++i) + if (ritem[i] >= 0) + { + count++; + symbol_count[ritem[i]]++; + } /* See comments before new_itemsets. All the vectors of items live inside KERNEL_ITEMS. The number of active items after @@ -98,8 +100,8 @@ allocate_itemsets (void) count += symbol_count[i]; } - shift_symbol = symbol_count; - kernel_end = XCALLOC (short *, nsyms); + free (symbol_count); + kernel_size = XCALLOC (int, nsyms); } @@ -110,20 +112,21 @@ allocate_storage (void) shiftset = XCALLOC (short, nsyms); redset = XCALLOC (short, nrules + 1); - state_table = XCALLOC (core *, STATE_TABLE_SIZE); + state_hash = XCALLOC (state_t *, STATE_HASH_SIZE); + shift_symbol = XCALLOC (short, 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); + free (state_hash); } @@ -137,51 +140,38 @@ free_storage (void) | 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. | +| shifted, and kernel_size[symbol] is their numbers. | `----------------------------------------------------------------*/ static void new_itemsets (void) { int i; - int shiftcount; - short *isp; - short *ksp; - int symbol; -#if TRACE - fprintf (stderr, "Entering new_itemsets, state = %d\n", - this_state->number); -#endif + if (trace_flag) + fprintf (stderr, "Entering new_itemsets, state = %d\n", + this_state->number); for (i = 0; i < nsyms; i++) - kernel_end[i] = NULL; + kernel_size[i] = 0; - shiftcount = 0; + nshifts = 0; - isp = itemset; - - while (isp < itemsetend) + for (i = 0; i < nitemset; ++i) { - i = *isp++; - symbol = ritem[i]; - if (symbol > 0) + int symbol = ritem[itemset[i]]; + if (symbol >= 0) { - ksp = kernel_end[symbol]; - - if (!ksp) + if (!kernel_size[symbol]) { - shift_symbol[shiftcount++] = symbol; - ksp = kernel_base[symbol]; + shift_symbol[nshifts] = symbol; + nshifts++; } - *ksp++ = i + 1; - kernel_end[symbol] = ksp; + kernel_base[symbol][kernel_size[symbol]] = itemset[i] + 1; + kernel_size[symbol]++; } } - - nshifts = shiftcount; } @@ -191,34 +181,33 @@ new_itemsets (void) | necessary. | `-----------------------------------------------------------------*/ -static core * +static state_t * new_state (int symbol) { - int n; - core *p; + state_t *p; -#if TRACE - fprintf (stderr, "Entering new_state, symbol = %d, state = %d\n", - symbol, nstates); -#endif + if (trace_flag) + fprintf (stderr, "Entering new_state, state = %d, symbol = %d (%s)\n", + this_state->number, symbol, symbols[symbol]->tag); if (nstates >= MAXSHORT) fatal (_("too many states (max %d)"), MAXSHORT); - n = kernel_end[symbol] - kernel_base[symbol]; - - p = CORE_ALLOC (n); + p = STATE_ALLOC (kernel_size[symbol]); p->accessing_symbol = symbol; p->number = nstates; - p->nitems = n; + p->nitems = kernel_size[symbol]; - shortcpy (p->items, kernel_base[symbol], n); + shortcpy (p->items, kernel_base[symbol], kernel_size[symbol]); last_state->next = p; last_state = p; - nstates++; + /* If this is the eoftoken, then this is the final state. */ + if (symbol == 0) + final_state = p->number; + return p; } @@ -226,54 +215,39 @@ new_state (int symbol) /*--------------------------------------------------------------. | 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. | +| equivalent one exists already. Used by append_states. | `--------------------------------------------------------------*/ static int get_state (int symbol) { int key; - short *isp1; - short *isp2; - short *iend; - core *sp; - int found; - - int n; - -#if TRACE - fprintf (stderr, "Entering get_state, symbol = %d\n", symbol); -#endif + int i; + state_t *sp; - isp1 = kernel_base[symbol]; - iend = kernel_end[symbol]; - n = iend - isp1; + if (trace_flag) + fprintf (stderr, "Entering get_state, state = %d, symbol = %d (%s)\n", + this_state->number, symbol, symbols[symbol]->tag); - /* add up the target state's active item numbers to get a hash key */ + /* Add up the target state's active item numbers to get a hash key. + */ key = 0; - while (isp1 < iend) - key += *isp1++; - - key = key % STATE_TABLE_SIZE; - - sp = state_table[key]; + for (i = 0; i < kernel_size[symbol]; ++i) + key += kernel_base[symbol][i]; + key = key % STATE_HASH_SIZE; + sp = state_hash[key]; if (sp) { - found = 0; + int found = 0; while (!found) { - if (sp->nitems == n) + if (sp->nitems == kernel_size[symbol]) { found = 1; - isp1 = kernel_base[symbol]; - isp2 = sp->items; - - while (found && isp1 < iend) - { - if (*isp1++ != *isp2++) - found = 0; - } + for (i = 0; i < kernel_size[symbol]; ++i) + if (kernel_base[symbol][i] != sp->items[i]) + found = 0; } if (!found) @@ -292,9 +266,12 @@ get_state (int symbol) } else /* bucket is empty */ { - state_table[key] = sp = new_state (symbol); + state_hash[key] = sp = new_state (symbol); } + if (trace_flag) + fprintf (stderr, "Exiting get_state => %d\n", sp->number); + return sp->number; } @@ -312,9 +289,9 @@ append_states (void) int j; int symbol; -#if TRACE - fprintf (stderr, "Entering append_states\n"); -#endif + if (trace_flag) + fprintf (stderr, "Entering append_states, state = %d\n", + this_state->number); /* first sort shift_symbol into increasing order */ @@ -331,250 +308,28 @@ append_states (void) } for (i = 0; i < nshifts; i++) - { - symbol = shift_symbol[i]; - shiftset[i] = get_state (symbol); - } + shiftset[i] = get_state (shift_symbol[i]); } static void new_states (void) { - core *p; - - p = CORE_ALLOC (0); - first_state = last_state = this_state = p; + 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; - - p = SHIFTS_ALLOC (nshifts); - - p->number = this_state->number; - p->nshifts = nshifts; - + shifts *p = shifts_new (nshifts); shortcpy (p->shifts, shiftset, nshifts); - - if (last_shift) - { - last_shift->next = p; - last_shift = 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 (); - } - - /* 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; + this_state->shifts = p; } @@ -587,48 +342,54 @@ augment_automaton (void) static void save_reductions (void) { - short *isp; - int item; - int count; - reductions *p; + int count = 0; + int i; - short *rend; + /* If this is the final state, we want it to have no reductions at + all, although it has one for `START_SYMBOL EOF .'. */ + if (this_state->number == final_state) + return; /* Find and count the active items that represent ends of rules. */ - - count = 0; - for (isp = itemset; isp < itemsetend; isp++) + for (i = 0; i < nitemset; ++i) { - item = ritem[*isp]; + int item = ritem[itemset[i]]; if (item < 0) redset[count++] = -item; } /* Make a reductions structure and copy the data into it. */ + this_state->reductions = reductions_new (count); + shortcpy (this_state->reductions->rules, redset, count); +} - 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) +{ + state_t *sp; + states = XCALLOC (state_t *, nstates); - if (last_reduction) - { - last_reduction->next = p; - last_reduction = p; - } - else - { - first_reduction = p; - last_reduction = p; - } + for (sp = first_state; sp; sp = sp->next) + { + /* Pessimization, but simplification of the code: make sure all + the states have a shifts, errs, and reductions, even if + reduced to 0. */ + if (!sp->shifts) + sp->shifts = shifts_new (0); + if (!sp->errs) + sp->errs = errs_new (0); + if (!sp->reductions) + sp->reductions = reductions_new (0); + + states[sp->number] = sp; } } - /*-------------------------------------------------------------------. | Compute the nondeterministic finite state machine (see state.h for | | details) from the grammar. | @@ -638,11 +399,15 @@ void generate_states (void) { allocate_storage (); - new_closure (nitems); + new_closure (nritems); new_states (); while (this_state) { + if (trace_flag) + fprintf (stderr, "Processing state %d (reached by %s)\n", + this_state->number, + symbols[this_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 @@ -657,8 +422,7 @@ generate_states (void) /* create the shifts structures for the shifts to those states, now that the state numbers transitioning to are known */ - if (nshifts > 0) - save_shifts (); + save_shifts (); /* states are queued when they are created; process them all */ this_state = this_state->next; @@ -668,6 +432,6 @@ generate_states (void) free_closure (); free_storage (); - /* set up initial and final states as parser wants them */ - augment_automaton (); + /* Set up STATES. */ + set_states (); }