X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/2686a6e713b2746ea8484850bdb51979ef520d94..f59c437a25af1e4c028d268cca3819476ef4f725:/src/LR0.c diff --git a/src/LR0.c b/src/LR0.c index 1ed8e92c..e3db49aa 100644 --- a/src/LR0.c +++ b/src/LR0.c @@ -1,98 +1,73 @@ /* Generate the nondeterministic finite state machine for bison, - Copyright (C) 1984, 1986, 1989 Free Software Foundation, Inc. + Copyright 1984, 1986, 1989, 2000 Free Software Foundation, Inc. -This file is part of Bison, the GNU Compiler Compiler. + This file is part of Bison, the GNU Compiler Compiler. -Bison is free software; you can redistribute it and/or modify -it under the terms of the GNU General Public License as published by -the Free Software Foundation; either version 2, or (at your option) -any later version. + Bison is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2, or (at your option) + any later version. -Bison is distributed in the hope that it will be useful, -but WITHOUT ANY WARRANTY; without even the implied warranty of -MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -GNU General Public License for more details. + Bison is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. -You should have received a copy of the GNU General Public License -along with Bison; see the file COPYING. If not, write to -the Free Software Foundation, Inc., 59 Temple Place - Suite 330, -Boston, MA 02111-1307, USA. */ + You should have received a copy of the GNU General Public License + along with Bison; see the file COPYING. If not, write to + the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ /* See comments in state.h for the data structures that represent it. The entry point is generate_states. */ -#include #include "system.h" -#include "machine.h" -#include "alloc.h" #include "gram.h" #include "state.h" - - -extern char *nullable; -extern short *itemset; -extern short *itemsetend; +#include "complain.h" +#include "closure.h" +#include "LR0.h" int nstates; int final_state; -core *first_state; -shifts *first_shift; -reductions *first_reduction; - -int get_state PARAMS((int)); -core *new_state PARAMS((int)); - -void allocate_itemsets PARAMS((void)); -void allocate_storage PARAMS((void)); -void free_storage PARAMS((void)); -void generate_states PARAMS((void)); -void new_itemsets PARAMS((void)); -void append_states PARAMS((void)); -void initialize_states PARAMS((void)); -void save_shifts PARAMS((void)); -void save_reductions PARAMS((void)); -void augment_automaton PARAMS((void)); -void insert_start_shift PARAMS((void)); -extern void initialize_closure PARAMS((int)); -extern void closure PARAMS((short *, int)); -extern void finalize_closure PARAMS((void)); -extern void toomany PARAMS((char *)); - -static core *this_state; -static core *last_state; -static shifts *last_shift; -static reductions *last_reduction; +core *first_state = NULL; +shifts *first_shift = NULL; +reductions *first_reduction = 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; +static short *shift_symbol = NULL; -static short *redset; -static short *shiftset; +static short *redset = NULL; +static short *shiftset = NULL; -static short **kernel_base; -static short **kernel_end; -static short *kernel_items; +static short **kernel_base = NULL; +static short **kernel_end = NULL; +static short *kernel_items = NULL; /* hash table for states, to recognize equivalent ones. */ #define STATE_TABLE_SIZE 1009 -static core **state_table; - +static core **state_table = NULL; - -void + +static void allocate_itemsets (void) { - register short *itemp; - register int symbol; - register int i; - register int count; - register short *symbol_count; + short *itemp = NULL; + int symbol; + int i; + int count; + short *symbol_count = NULL; count = 0; - symbol_count = NEW2(nsyms, short); + symbol_count = XCALLOC (short, nsyms); itemp = ritem; symbol = *itemp++; @@ -106,14 +81,15 @@ allocate_itemsets (void) symbol = *itemp++; } - /* see comments before new_itemsets. All the vectors of items - live inside kernel_items. The number of active items after + /* 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]. We allocate that much space for each symbol. */ - kernel_base = NEW2(nsyms, short *); - kernel_items = NEW2(count, short); + kernel_base = XCALLOC (short *, nsyms); + if (count) + kernel_items = XCALLOC (short, count); count = 0; for (i = 0; i < nsyms; i++) @@ -123,94 +99,60 @@ allocate_itemsets (void) } shift_symbol = symbol_count; - kernel_end = NEW2(nsyms, short *); + kernel_end = XCALLOC (short *, nsyms); } -void +static void allocate_storage (void) { - allocate_itemsets(); + allocate_itemsets (); - shiftset = NEW2(nsyms, short); - redset = NEW2(nrules + 1, short); - state_table = NEW2(STATE_TABLE_SIZE, core *); + shiftset = XCALLOC (short, nsyms); + redset = XCALLOC (short, nrules + 1); + state_table = XCALLOC (core *, STATE_TABLE_SIZE); } -void +static void free_storage (void) { - FREE(shift_symbol); - FREE(redset); - FREE(shiftset); - FREE(kernel_base); - FREE(kernel_end); - FREE(kernel_items); - FREE(state_table); + XFREE (shift_symbol); + XFREE (redset); + XFREE (shiftset); + XFREE (kernel_base); + XFREE (kernel_end); + XFREE (kernel_items); + XFREE (state_table); } -/* compute the nondeterministic finite state machine (see state.h for details) -from the grammar. */ -void -generate_states (void) -{ - allocate_storage(); - initialize_closure(nitems); - initialize_states(); - - while (this_state) - { - /* 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; - } - - /* discard various storage */ - finalize_closure(); - free_storage(); - - /* set up initial and final states as parser wants them */ - augment_automaton(); -} - +/*----------------------------------------------------------------. +| 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 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. */ -void +static void new_itemsets (void) { - register int i; - register int shiftcount; - register short *isp; - register short *ksp; - register int symbol; - -#ifdef TRACE - fprintf(stderr, "Entering new_itemsets\n"); + int i; + int shiftcount; + short *isp; + short *ksp; + int symbol; + +#if TRACE + fprintf (stderr, "Entering new_itemsets, state = %d\n", + this_state->number); #endif for (i = 0; i < nsyms; i++) @@ -226,16 +168,16 @@ new_itemsets (void) symbol = ritem[i]; if (symbol > 0) { - ksp = kernel_end[symbol]; + ksp = kernel_end[symbol]; - if (!ksp) + if (!ksp) { shift_symbol[shiftcount++] = symbol; ksp = kernel_base[symbol]; } - *ksp++ = i + 1; - kernel_end[symbol] = ksp; + *ksp++ = i + 1; + kernel_end[symbol] = ksp; } } @@ -244,63 +186,70 @@ new_itemsets (void) -/* Use the information computed by new_itemsets to find the state numbers - reached by each shift transition from the current state. +/*-----------------------------------------------------------------. +| Subroutine of get_state. Create a new state for those items, if | +| necessary. | +`-----------------------------------------------------------------*/ - shiftset is set up as a vector of state numbers of those states. */ -void -append_states (void) +static core * +new_state (int symbol) { - register int i; - register int j; - register int symbol; - -#ifdef TRACE - fprintf(stderr, "Entering append_states\n"); + int n; + core *p; + short *isp1; + short *isp2; + short *iend; + +#if TRACE + fprintf (stderr, "Entering new_state, symbol = %d, state = %d\n", + symbol, nstates); #endif - /* first sort shift_symbol into increasing order */ + if (nstates >= MAXSHORT) + fatal (_("too many states (max %d)"), MAXSHORT); - 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; - } + isp1 = kernel_base[symbol]; + iend = kernel_end[symbol]; + n = iend - isp1; - for (i = 0; i < nshifts; i++) - { - symbol = shift_symbol[i]; - shiftset[i] = get_state(symbol); - } -} + p = CORE_ALLOC (n); + p->accessing_symbol = symbol; + p->number = nstates; + p->nitems = n; + + isp2 = p->items; + while (isp1 < iend) + *isp2++ = *isp1++; + + 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 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. | +`--------------------------------------------------------------*/ -int +static int get_state (int symbol) { - register int key; - register short *isp1; - register short *isp2; - register short *iend; - register core *sp; - register int found; + int key; + short *isp1; + short *isp2; + short *iend; + core *sp; + int found; int n; -#ifdef TRACE - fprintf(stderr, "Entering get_state, symbol = %d\n", symbol); +#if TRACE + fprintf (stderr, "Entering get_state, symbol = %d\n", symbol); #endif isp1 = kernel_base[symbol]; @@ -340,88 +289,82 @@ get_state (int symbol) { sp = sp->link; } - else /* bucket exhausted and no match */ + else /* bucket exhausted and no match */ { - sp = sp->link = new_state(symbol); + sp = sp->link = new_state (symbol); found = 1; } } } } - else /* bucket is empty */ + else /* bucket is empty */ { - state_table[key] = sp = new_state(symbol); + state_table[key] = sp = new_state (symbol); } - return (sp->number); + return sp->number; } +/*------------------------------------------------------------------. +| 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. | +`------------------------------------------------------------------*/ - -/* subroutine of get_state. create a new state for those items, if necessary. */ - -core * -new_state (int symbol) +static void +append_states (void) { - register int n; - register core *p; - register short *isp1; - register short *isp2; - register short *iend; - -#ifdef TRACE - fprintf(stderr, "Entering new_state, symbol = %d\n", symbol); -#endif - - if (nstates >= MAXSHORT) - toomany("states"); - - isp1 = kernel_base[symbol]; - iend = kernel_end[symbol]; - n = iend - isp1; - - p = (core *) xmalloc((unsigned) (sizeof(core) + (n - 1) * sizeof(short))); - p->accessing_symbol = symbol; - p->number = nstates; - p->nitems = n; + int i; + int j; + int symbol; - isp2 = p->items; - while (isp1 < iend) - *isp2++ = *isp1++; +#if TRACE + fprintf (stderr, "Entering append_states\n"); +#endif - last_state->next = p; - last_state = p; + /* first sort shift_symbol into increasing order */ - nstates++; + 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; + } - return (p); + for (i = 0; i < nshifts; i++) + { + symbol = shift_symbol[i]; + shiftset[i] = get_state (symbol); + } } -void -initialize_states (void) +static void +new_states (void) { - register core *p; -/* register unsigned *rp1; JF unused */ -/* register unsigned *rp2; JF unused */ -/* register unsigned *rend; JF unused */ + core *p; - p = (core *) xmalloc((unsigned) (sizeof(core) - sizeof(short))); + p = CORE_ALLOC (0); first_state = last_state = this_state = p; nstates = 1; } -void +static void save_shifts (void) { - register shifts *p; - register short *sp1; - register short *sp2; - register short *send; + shifts *p; + short *sp1; + short *sp2; + short *send; - p = (shifts *) xmalloc((unsigned) (sizeof(shifts) + - (nshifts - 1) * sizeof(short))); + p = SHIFTS_ALLOC (nshifts); p->number = this_state->number; p->nshifts = nshifts; @@ -446,80 +389,52 @@ save_shifts (void) } +/*------------------------------------------------------------------. +| Subroutine of augment_automaton. Create the next-to-final state, | +| to which a shift has already been made in the initial state. | +`------------------------------------------------------------------*/ -/* find which rules can be used for reduction transitions from the current state - and make a reductions structure for the state to record their rule numbers. */ -void -save_reductions (void) +static void +insert_start_shift (void) { - register short *isp; - register short *rp1; - register short *rp2; - register int item; - register int count; - register reductions *p; - - short *rend; - - /* find and count the active items that represent ends of rules */ - - count = 0; - for (isp = itemset; isp < itemsetend; isp++) - { - item = ritem[*isp]; - if (item < 0) - { - redset[count++] = -item; - } - } - - /* make a reductions structure and copy the data into it. */ + core *statep; + shifts *sp; - if (count) - { - p = (reductions *) xmalloc((unsigned) (sizeof(reductions) + - (count - 1) * sizeof(short))); - - p->number = this_state->number; - p->nreds = count; + statep = CORE_ALLOC (0); + statep->number = nstates; + statep->accessing_symbol = start_symbol; - rp1 = redset; - rp2 = p->rules; - rend = rp1 + count; + last_state->next = statep; + last_state = statep; - while (rp1 < rend) - *rp2++ = *rp1++; + /* 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; - if (last_reduction) - { - last_reduction->next = p; - last_reduction = p; - } - else - { - first_reduction = p; - last_reduction = p; - } - } + 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. | +`------------------------------------------------------------------*/ -/* 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. */ -void +static void augment_automaton (void) { - register int i; - register int k; -/* register int found; JF unused */ - register core *statep; - register shifts *sp; - register shifts *sp2; - register shifts *sp1 = NULL; + int i; + int k; + core *statep; + shifts *sp; + shifts *sp2; + shifts *sp1 = NULL; sp = first_shift; @@ -533,13 +448,13 @@ augment_automaton (void) /* 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->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. */ + Make sure it has a shift to what will be the final state. */ k = statep->number; while (sp && sp->number < k) @@ -550,8 +465,7 @@ augment_automaton (void) if (sp && sp->number == k) { - sp2 = (shifts *) xmalloc((unsigned) (sizeof(shifts) - + sp->nshifts * sizeof(short))); + sp2 = SHIFTS_ALLOC (sp->nshifts + 1); sp2->number = k; sp2->nshifts = sp->nshifts + 1; sp2->shifts[0] = nstates; @@ -564,11 +478,11 @@ augment_automaton (void) sp1->next = sp2; if (sp == last_shift) last_shift = sp2; - FREE(sp); + XFREE (sp); } else { - sp2 = NEW(shifts); + sp2 = SHIFTS_ALLOC (1); sp2->number = k; sp2->nshifts = 1; sp2->shifts[0] = nstates; @@ -584,11 +498,10 @@ augment_automaton (void) { /* 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). */ + going to the next-to-final state (yet to be made). */ sp = first_shift; - sp2 = (shifts *) xmalloc(sizeof(shifts) - + sp->nshifts * sizeof(short)); + sp2 = SHIFTS_ALLOC (sp->nshifts + 1); sp2->nshifts = sp->nshifts + 1; /* Stick this shift into the vector at the proper place. */ @@ -604,24 +517,24 @@ augment_automaton (void) sp2->shifts[k++] = nstates; /* Patch sp2 into the chain of shifts - in place of sp, at the beginning. */ + in place of sp, at the beginning. */ sp2->next = sp->next; first_shift = sp2; if (last_shift == sp) last_shift = sp2; - FREE(sp); + XFREE (sp); /* Create the next-to-final state, with shift to - what will be the final state. */ - insert_start_shift(); + 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 = NEW(shifts); + sp = SHIFTS_ALLOC (1); sp->nshifts = 1; sp->shifts[0] = nstates; @@ -631,15 +544,15 @@ augment_automaton (void) /* Create the next-to-final state, with shift to what will be the final state. */ - insert_start_shift(); + insert_start_shift (); } } else { /* There are no shifts for any state. - Make one shift, from the initial state to the next-to-final state. */ + Make one shift, from the initial state to the next-to-final state. */ - sp = NEW(shifts); + sp = SHIFTS_ALLOC (1); sp->nshifts = 1; sp->shifts[0] = nstates; @@ -648,20 +561,20 @@ augment_automaton (void) last_shift = sp; /* Create the next-to-final state, with shift to - what will be the final state. */ - insert_start_shift(); + 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 *) xmalloc((unsigned) (sizeof(core) - sizeof(short))); + 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 = NEW(shifts); + sp = SHIFTS_ALLOC (1); sp->number = nstates++; sp->nshifts = 1; sp->shifts[0] = nstates; @@ -673,35 +586,110 @@ augment_automaton (void) final_state = nstates; /* Make the termination state. */ - statep = (core *) xmalloc((unsigned) (sizeof(core) - sizeof(short))); + statep = CORE_ALLOC (0); statep->number = nstates++; last_state->next = statep; last_state = statep; } -/* subroutine of augment_automaton. - Create the next-to-final state, to which a shift has already been made in - the initial state. */ +/*----------------------------------------------------------------. +| Find which rules can be used for reduction transitions from the | +| current state and make a reductions structure for the state to | +| record their rule numbers. | +`----------------------------------------------------------------*/ + +static void +save_reductions (void) +{ + short *isp; + short *rp1; + short *rp2; + int item; + int count; + reductions *p; + + short *rend; + + /* Find and count the active items that represent ends of rules. */ + + count = 0; + for (isp = itemset; isp < itemsetend; isp++) + { + item = ritem[*isp]; + if (item < 0) + redset[count++] = -item; + } + + /* Make a reductions structure and copy the data into it. */ + + if (count) + { + p = REDUCTIONS_ALLOC (count); + + p->number = this_state->number; + p->nreds = count; + + rp1 = redset; + rp2 = p->rules; + rend = rp1 + count; + + for (/* nothing */; rp1 < rend; ++rp1, ++rp2) + *rp2 = *rp1; + + if (last_reduction) + { + last_reduction->next = p; + last_reduction = p; + } + else + { + first_reduction = p; + last_reduction = p; + } + } +} + + +/*-------------------------------------------------------------------. +| Compute the nondeterministic finite state machine (see state.h for | +| details) from the grammar. | +`-------------------------------------------------------------------*/ + void -insert_start_shift (void) +generate_states (void) { - register core *statep; - register shifts *sp; + allocate_storage (); + new_closure (nitems); + new_states (); - statep = (core *) xmalloc((unsigned) (sizeof(core) - sizeof(short))); - statep->number = nstates; - statep->accessing_symbol = start_symbol; + while (this_state) + { + /* 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 (); - last_state->next = statep; - last_state = statep; + /* create the shifts structures for the shifts to those states, + now that the state numbers transitioning to are known */ + if (nshifts > 0) + save_shifts (); - /* Make a shift from this state to (what will be) the final state. */ - sp = NEW(shifts); - sp->number = nstates++; - sp->nshifts = 1; - sp->shifts[0] = nstates; + /* states are queued when they are created; process them all */ + this_state = this_state->next; + } - last_shift->next = sp; - last_shift = sp; + /* discard various storage */ + free_closure (); + free_storage (); + + /* set up initial and final states as parser wants them */ + augment_automaton (); }