X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/0e41b407b93a89894b655e47a148c03d273cfd87..e9f87b5b7df2e328d2e4196d276c0d96594c906b:/src/LR0.c diff --git a/src/LR0.c b/src/LR0.c index 06ee51f6..e914c6ef 100644 --- a/src/LR0.c +++ b/src/LR0.c @@ -23,6 +23,7 @@ The entry point is generate_states. */ #include "system.h" +#include "symtab.h" #include "getargs.h" #include "reader.h" #include "gram.h" @@ -30,18 +31,22 @@ #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; @@ -55,22 +60,24 @@ 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) { 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); - for (i = 0; ritem[i]; ++i) - if (ritem[i] > 0) + for (i = 0; i < nritems; ++i) + if (ritem[i] >= 0) { count++; symbol_count[ritem[i]]++; @@ -93,7 +100,7 @@ allocate_itemsets (void) count += symbol_count[i]; } - shift_symbol = symbol_count; + free (symbol_count); kernel_size = XCALLOC (int, nsyms); } @@ -105,20 +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_size); + free (shift_symbol); + free (redset); + free (shiftset); + free (kernel_base); + free (kernel_size); XFREE (kernel_items); - XFREE (state_table); + free (state_hash); } @@ -139,7 +147,6 @@ static void new_itemsets (void) { int i; - int shiftcount; if (trace_flag) fprintf (stderr, "Entering new_itemsets, state = %d\n", @@ -148,25 +155,23 @@ new_itemsets (void) for (i = 0; i < nsyms; i++) kernel_size[i] = 0; - shiftcount = 0; + nshifts = 0; - for (i = 0; i < itemsetsize; ++i) + for (i = 0; i < nitemset; ++i) { int symbol = ritem[itemset[i]]; - if (symbol > 0) + if (symbol >= 0) { if (!kernel_size[symbol]) { - shift_symbol[shiftcount] = symbol; - shiftcount++; + shift_symbol[nshifts] = symbol; + nshifts++; } kernel_base[symbol][kernel_size[symbol]] = itemset[i] + 1; kernel_size[symbol]++; } } - - nshifts = shiftcount; } @@ -176,19 +181,19 @@ new_itemsets (void) | necessary. | `-----------------------------------------------------------------*/ -static core * +static state_t * new_state (int symbol) { - core *p; + state_t *p; if (trace_flag) fprintf (stderr, "Entering new_state, state = %d, symbol = %d (%s)\n", - this_state->number, symbol, tags[symbol]); + this_state->number, symbol, symbols[symbol]->tag); if (nstates >= MAXSHORT) fatal (_("too many states (max %d)"), MAXSHORT); - p = CORE_ALLOC (kernel_size[symbol]); + p = STATE_ALLOC (kernel_size[symbol]); p->accessing_symbol = symbol; p->number = nstates; p->nitems = kernel_size[symbol]; @@ -199,6 +204,10 @@ new_state (int symbol) last_state = p; nstates++; + /* If this is the eoftoken, then this is the final state. */ + if (symbol == 0) + final_state = p->number; + return p; } @@ -214,19 +223,19 @@ get_state (int symbol) { int key; int i; - core *sp; + state_t *sp; if (trace_flag) fprintf (stderr, "Entering get_state, state = %d, symbol = %d (%s)\n", - this_state->number, symbol, tags[symbol]); + this_state->number, 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_TABLE_SIZE; - sp = state_table[key]; + key = key % STATE_HASH_SIZE; + sp = state_hash[key]; if (sp) { @@ -257,7 +266,7 @@ 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) @@ -306,230 +315,21 @@ append_states (void) static void new_states (void) { - first_state = last_state = this_state = CORE_ALLOC (0); + 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_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; - 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; } @@ -542,13 +342,16 @@ augment_automaton (void) static void save_reductions (void) { - int count; + int count = 0; int i; - /* Find and count the active items that represent ends of rules. */ + /* 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; - count = 0; - for (i = 0; i < itemsetsize; ++i) + /* Find and count the active items that represent ends of rules. */ + for (i = 0; i < nitemset; ++i) { int item = ritem[itemset[i]]; if (item < 0) @@ -556,25 +359,37 @@ save_reductions (void) } /* 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) - { - reductions *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; - 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. | @@ -584,11 +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 @@ -603,8 +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; @@ -614,6 +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 (); }