X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/d200e455d069992b6a491a0fbf1cb39a10c6937b..b408954b40e74d85ee90544ea7e296dbc99356c9:/src/LR0.c diff --git a/src/LR0.c b/src/LR0.c index 148e2bc0..efe9589a 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, 2001 Free Software Foundation, Inc. + Copyright 1984, 1986, 1989, 2000, 2001, 2002 Free Software Foundation, Inc. This file is part of Bison, the GNU Compiler Compiler. @@ -23,6 +23,10 @@ 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" @@ -33,22 +37,29 @@ #include "lalr.h" #include "reduce.h" -int nstates; -int final_state; +unsigned int nstates = 0; +/* 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 state_t *this_state = NULL; static state_t *last_state = NULL; static int nshifts; -static short *shift_symbol = NULL; +static symbol_number_t *shift_symbol = NULL; static short *redset = NULL; static short *shiftset = NULL; -static short **kernel_base = NULL; +static item_number_t **kernel_base = NULL; static int *kernel_size = NULL; -static short *kernel_items = NULL; +static item_number_t *kernel_items = NULL; /* hash table for states, to recognize equivalent ones. */ @@ -59,7 +70,8 @@ static state_t **state_hash = NULL; static void allocate_itemsets (void) { - int i; + int i, r; + item_number_t *rhsp; /* Count the number of occurrences of all the symbols in RITEMS. Note that useless productions (hence useless nonterminals) are @@ -68,11 +80,11 @@ 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 = 1; r < nrules + 1; ++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 @@ -81,9 +93,9 @@ allocate_itemsets (void) 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++) @@ -105,6 +117,7 @@ allocate_storage (void) shiftset = XCALLOC (short, nsyms); redset = XCALLOC (short, nrules + 1); state_hash = XCALLOC (state_t *, STATE_HASH_SIZE); + shift_symbol = XCALLOC (symbol_number_t, nsyms); } @@ -146,24 +159,22 @@ new_itemsets (void) 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]++; + } } @@ -174,26 +185,37 @@ new_itemsets (void) `-----------------------------------------------------------------*/ static state_t * -new_state (int symbol) +new_state (symbol_number_t symbol, size_t core_size, item_number_t *core) { state_t *p; if (trace_flag) fprintf (stderr, "Entering new_state, state = %d, symbol = %d (%s)\n", - this_state->number, symbol, tags[symbol]); + nstates, symbol, quotearg_style (escape_quoting_style, + symbols[symbol]->tag)); - if (nstates >= MAXSHORT) - fatal (_("too many states (max %d)"), MAXSHORT); + if (nstates >= SHRT_MAX) + fatal (_("too many states (max %d)"), SHRT_MAX); - p = STATE_ALLOC (kernel_size[symbol]); + p = STATE_ALLOC (core_size); p->accessing_symbol = symbol; p->number = nstates; - p->nitems = kernel_size[symbol]; + p->solved_conflicts = NULL; + + p->nitems = core_size; + memcpy (p->items, core, core_size * sizeof (core[0])); - shortcpy (p->items, kernel_base[symbol], kernel_size[symbol]); + /* 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 = p->number; - last_state->next = p; + if (!first_state) + first_state = p; + if (last_state) + last_state->next = p; last_state = p; + nstates++; return p; @@ -207,21 +229,22 @@ new_state (int symbol) `--------------------------------------------------------------*/ static int -get_state (int symbol) +get_state (symbol_number_t symbol, size_t core_size, item_number_t *core) { int key; - int i; + size_t i; 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, quotearg_style (escape_quoting_style, + 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]; + for (i = 0; i < core_size; ++i) + key += core[i]; key = key % STATE_HASH_SIZE; sp = state_hash[key]; @@ -230,11 +253,11 @@ get_state (int symbol) int found = 0; while (!found) { - if (sp->nitems == kernel_size[symbol]) + if (sp->nitems == core_size) { found = 1; - for (i = 0; i < kernel_size[symbol]; ++i) - if (kernel_base[symbol][i] != sp->items[i]) + for (i = 0; i < core_size; ++i) + if (core[i] != sp->items[i]) found = 0; } @@ -246,7 +269,7 @@ get_state (int symbol) } else /* bucket exhausted and no match */ { - sp = sp->link = new_state (symbol); + sp = sp->link = new_state (symbol, core_size, core); found = 1; } } @@ -254,7 +277,7 @@ get_state (int symbol) } else /* bucket is empty */ { - state_hash[key] = sp = new_state (symbol); + state_hash[key] = sp = new_state (symbol, core_size, core); } if (trace_flag) @@ -275,7 +298,7 @@ append_states (void) { int i; int j; - int symbol; + symbol_number_t symbol; if (trace_flag) fprintf (stderr, "Entering append_states, state = %d\n", @@ -296,15 +319,21 @@ append_states (void) } for (i = 0; i < nshifts; i++) - shiftset[i] = get_state (shift_symbol[i]); + { + symbol = shift_symbol[i]; + shiftset[i] = get_state (symbol, + kernel_size[symbol], kernel_base[symbol]); + } } static void new_states (void) { - first_state = last_state = this_state = STATE_ALLOC (0); - nstates = 1; + /* The 0 at the lhs is the index of the item of this initial rule. */ + kernel_base[0][0] = 0; + kernel_size[0] = 1; + this_state = new_state (0, kernel_size[0], kernel_base[0]); } @@ -316,189 +345,11 @@ static void save_shifts (void) { shifts *p = shifts_new (nshifts); - shortcpy (p->shifts, shiftset, nshifts); + memcpy (p->shifts, shiftset, nshifts * sizeof (shiftset[0])); this_state->shifts = 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->shifts[0] = nstates; -} - - -/*-----------------------------------------------------------------. -| 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->shifts[0] = nstates; -} - - -/*---------------------------------------------------------------. -| 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_state->shifts->nshifts) - { - /* The first state has no shifts. 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; - - /* Create the next-to-final state, with shift to - what will be the final state. */ - insert_start_shifting_state (); - } - else - { - state_t *statep = first_state->next; - /* The states reached by shifts from FIRST_STATE are numbered - 1..(SP->NSHIFTS). Look for one reached by START_SYMBOL. - This is typical of `start: start ... ;': there is a state - with the item `start: start . ...'. We want to add a `shift - on EOF to eof-shifting state here. */ - while (statep->accessing_symbol != start_symbol - && statep->number < first_state->shifts->nshifts) - statep = statep->next; - - if (statep->accessing_symbol == start_symbol) - { - /* We already have STATEP, a next-to-final state for `start: - start . ...'. Make sure it has a shift to what will be - the final state. */ - int i; - - /* Find the shift of the inital state that leads to STATEP. */ - shifts *sp = statep->shifts; - - shifts *sp1 = shifts_new (sp->nshifts + 1); - statep->shifts = sp1; - sp1->shifts[0] = nstates; - for (i = sp->nshifts; i > 0; i--) - sp1->shifts[i] = sp->shifts[i - 1]; - - XFREE (sp); - - insert_eof_shifting_state (); - } - else - { - /* There is no state for `start: start . ...'. */ - int i, k; - shifts *sp = first_state->shifts; - shifts *sp1 = NULL; - - /* Add one more shift to the initial state, going to the - next-to-final state (yet to be made). */ - sp1 = shifts_new (sp->nshifts + 1); - first_state->shifts = sp1; - /* 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) - sp1->shifts[k++] = nstates; - sp1->shifts[k] = sp->shifts[i]; - statep = statep->next; - } - if (i == k) - sp1->shifts[k++] = nstates; - - XFREE (sp); - - /* Create the next-to-final state, with shift to what will - be the final state. Corresponds to `start: start . ...'. */ - insert_start_shifting_state (); - } - } - - insert_accepting_state (); -} - - /*----------------------------------------------------------------. | Find which rules can be used for reduction transitions from the | | current state and make a reductions structure for the state to | @@ -508,13 +359,16 @@ 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 < nitemset; ++i) + /* 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) @@ -522,41 +376,35 @@ save_reductions (void) } /* 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; - } + this_state->reductions = reductions_new (count); + memcpy (this_state->reductions->rules, redset, count * sizeof (redset[0])); } -/*--------------------. -| Build STATE_TABLE. | -`--------------------*/ +/*---------------. +| Build STATES. | +`---------------*/ static void -set_state_table (void) +set_states (void) { - state_table = XCALLOC (state_t *, nstates); - - { - 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); - } + state_t *sp; + states = XCALLOC (state_t *, nstates); + + 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; + } } /*-------------------------------------------------------------------. @@ -568,14 +416,16 @@ 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, tags[this_state->accessing_symbol]); + this_state->number, + quotearg_style (escape_quoting_style, + 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 @@ -600,9 +450,6 @@ generate_states (void) 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 (); }