X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/5dde542557baf1e74af051af6391a9e942ca1ead..927b425baae16fc1d50e092b78b944e281b521f6:/src/lalr.c diff --git a/src/lalr.c b/src/lalr.c index 0d79be65..65c55ab7 100644 --- a/src/lalr.c +++ b/src/lalr.c @@ -1,6 +1,7 @@ -/* Compute look-ahead criteria for bison, - Copyright (C) 1984, 1986, 1989, 2000, 2001, 2002 - Free Software Foundation, Inc. +/* Compute look-ahead criteria for Bison. + + Copyright (C) 1984, 1986, 1989, 2000, 2001, 2002, 2003, 2004, 2005, + 2006 Free Software Foundation, Inc. This file is part of Bison, the GNU Compiler Compiler. @@ -16,14 +17,15 @@ 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. */ + the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, + Boston, MA 02110-1301, USA. */ /* Compute how to make the finite state machine deterministic; find - which rules need lookahead in each state, and which lookahead + which rules need look-ahead in each state, and which look-ahead tokens they accept. */ +#include #include "system.h" #include @@ -41,10 +43,10 @@ #include "relation.h" #include "symtab.h" -goto_number *goto_map = NULL; -static goto_number ngotos = 0; -state_number *from_state = NULL; -state_number *to_state = NULL; +goto_number *goto_map; +static goto_number ngotos; +state_number *from_state; +state_number *to_state; /* Linked list of goto numbers. */ typedef struct goto_list @@ -79,8 +81,8 @@ set_goto_map (void) state_number s; goto_number *temp_map; - goto_map = XCALLOC (goto_number, nvars + 1) - ntokens; - temp_map = XCALLOC (goto_number, nvars + 1) - ntokens; + goto_map = xcalloc (nvars + 1, sizeof *goto_map); + temp_map = xnmalloc (nvars + 1, sizeof *temp_map); ngotos = 0; for (s = 0; s < nstates; ++s) @@ -89,31 +91,33 @@ set_goto_map (void) int i; for (i = sp->num - 1; i >= 0 && TRANSITION_IS_GOTO (sp, i); --i) { - if (ngotos >= GOTO_NUMBER_MAXIMUM) - abort (); ngotos++; - goto_map[TRANSITION_SYMBOL (sp, i)]++; + + /* Abort if (ngotos + 1) would overflow. */ + assert (ngotos != GOTO_NUMBER_MAXIMUM); + + goto_map[TRANSITION_SYMBOL (sp, i) - ntokens]++; } } { - int k = 0; + goto_number k = 0; int i; for (i = ntokens; i < nsyms; i++) { - temp_map[i] = k; - k += goto_map[i]; + temp_map[i - ntokens] = k; + k += goto_map[i - ntokens]; } for (i = ntokens; i < nsyms; i++) - goto_map[i] = temp_map[i]; + goto_map[i - ntokens] = temp_map[i - ntokens]; - goto_map[nsyms] = ngotos; - temp_map[nsyms] = ngotos; + goto_map[nsyms - ntokens] = ngotos; + temp_map[nsyms - ntokens] = ngotos; } - from_state = XCALLOC (state_number, ngotos); - to_state = XCALLOC (state_number, ngotos); + from_state = xcalloc (ngotos, sizeof *from_state); + to_state = xcalloc (ngotos, sizeof *to_state); for (s = 0; s < nstates; ++s) { @@ -121,13 +125,13 @@ set_goto_map (void) int i; for (i = sp->num - 1; i >= 0 && TRANSITION_IS_GOTO (sp, i); --i) { - int k = temp_map[TRANSITION_SYMBOL (sp, i)]++; + goto_number k = temp_map[TRANSITION_SYMBOL (sp, i) - ntokens]++; from_state[k] = s; to_state[k] = sp->states[i]->number; } } - XFREE (temp_map + ntokens); + free (temp_map); } @@ -136,21 +140,20 @@ set_goto_map (void) | Map a state/symbol pair into its numeric representation. | `----------------------------------------------------------*/ -static int +static goto_number map_goto (state_number s0, symbol_number sym) { - int high; - int low; - int middle; + goto_number high; + goto_number low; + goto_number middle; state_number s; - low = goto_map[sym]; - high = goto_map[sym + 1] - 1; + low = goto_map[sym - ntokens]; + high = goto_map[sym - ntokens + 1] - 1; for (;;) { - if (high < low) - abort (); + assert (low <= high); middle = (low + high) / 2; s = from_state[middle]; if (s == s0) @@ -166,11 +169,11 @@ map_goto (state_number s0, symbol_number sym) static void initialize_F (void) { - goto_number **reads = XCALLOC (goto_number *, ngotos); - goto_number *edge = XCALLOC (goto_number, ngotos + 1); - int nedges = 0; + goto_number **reads = xnmalloc (ngotos, sizeof *reads); + goto_number *edge = xnmalloc (ngotos + 1, sizeof *edge); + goto_number nedges = 0; - int i; + goto_number i; F = bitsetv_create (ngotos, ntokens, BITSET_FIXED); @@ -186,15 +189,17 @@ initialize_F (void) for (; j < sp->num; j++) { symbol_number sym = TRANSITION_SYMBOL (sp, j); - if (nullable[sym]) + if (nullable[sym - ntokens]) edge[nedges++] = map_goto (stateno, sym); } - if (nedges) + if (nedges == 0) + reads[i] = NULL; + else { - reads[i] = XCALLOC (goto_number, nedges + 1); - memcpy (reads[i], edge, nedges * sizeof (edge[0])); - reads[i][nedges] = -1; + reads[i] = xnmalloc (nedges + 1, sizeof reads[i][0]); + memcpy (reads[i], edge, nedges * sizeof edge[0]); + reads[i][nedges] = END_NODE; nedges = 0; } } @@ -202,21 +207,21 @@ initialize_F (void) relation_digraph (reads, ngotos, &F); for (i = 0; i < ngotos; i++) - XFREE (reads[i]); + free (reads[i]); - XFREE (reads); - XFREE (edge); + free (reads); + free (edge); } static void -add_lookback_edge (state *s, rule *r, int gotono) +add_lookback_edge (state *s, rule *r, goto_number gotono) { int ri = state_reduction_find (s, r); - goto_list *sp = XCALLOC (goto_list, 1); - sp->next = lookback[(s->reductions->lookaheads - LA) + ri]; + goto_list *sp = xmalloc (sizeof *sp); + sp->next = lookback[(s->reductions->look_ahead_tokens - LA) + ri]; sp->value = gotono; - lookback[(s->reductions->lookaheads - LA) + ri] = sp; + lookback[(s->reductions->look_ahead_tokens - LA) + ri] = sp; } @@ -224,11 +229,11 @@ add_lookback_edge (state *s, rule *r, int gotono) static void build_relations (void) { - goto_number *edge = XCALLOC (goto_number, ngotos + 1); - state_number *states1 = XCALLOC (state_number, ritem_longest_rhs () + 1); - int i; + goto_number *edge = xnmalloc (ngotos + 1, sizeof *edge); + state_number *states1 = xnmalloc (ritem_longest_rhs () + 1, sizeof *states1); + goto_number i; - includes = XCALLOC (goto_number *, ngotos); + includes = xnmalloc (ngotos, sizeof *includes); for (i = 0; i < ngotos; i++) { @@ -236,15 +241,15 @@ build_relations (void) symbol_number symbol1 = states[to_state[i]]->accessing_symbol; rule **rulep; - for (rulep = derives[symbol1]; *rulep; rulep++) + for (rulep = derives[symbol1 - ntokens]; *rulep; rulep++) { - int done; + bool done; int length = 1; - item_number *rp; + item_number const *rp; state *s = states[from_state[i]]; states1[0] = s->number; - for (rp = (*rulep)->rhs; *rp >= 0; rp++) + for (rp = (*rulep)->rhs; ! item_number_is_rule_number (*rp); rp++) { s = transitions_to (s->transitions, item_number_as_symbol_number (*rp)); @@ -255,35 +260,39 @@ build_relations (void) add_lookback_edge (s, *rulep, i); length--; - done = 0; + done = false; while (!done) { - done = 1; + done = true; + /* Each rhs ends in an item number, and there is a + sentinel before the first rhs, so it is safe to + decrement RP here. */ rp--; - /* JF added rp>=ritem && I hope to god its right! */ - if (rp >= ritem && ISVAR (*rp)) + if (ISVAR (*rp)) { /* Downcasting from item_number to symbol_number. */ edge[nedges++] = map_goto (states1[--length], item_number_as_symbol_number (*rp)); - if (nullable[*rp]) - done = 0; + if (nullable[*rp - ntokens]) + done = false; } } } - if (nedges) + if (nedges == 0) + includes[i] = NULL; + else { int j; - includes[i] = XCALLOC (goto_number, nedges + 1); + includes[i] = xnmalloc (nedges + 1, sizeof includes[i][0]); for (j = 0; j < nedges; j++) includes[i][j] = edge[j]; - includes[i][nedges] = -1; + includes[i][nedges] = END_NODE; } } - XFREE (edge); - XFREE (states1); + free (edge); + free (states1); relation_transpose (&includes, ngotos); } @@ -293,19 +302,19 @@ build_relations (void) static void compute_FOLLOWS (void) { - int i; + goto_number i; relation_digraph (includes, ngotos, &F); for (i = 0; i < ngotos; i++) - XFREE (includes[i]); + free (includes[i]); - XFREE (includes); + free (includes); } static void -compute_lookaheads (void) +compute_look_ahead_tokens (void) { size_t i; goto_list *sp; @@ -318,32 +327,32 @@ compute_lookaheads (void) for (i = 0; i < nLA; i++) LIST_FREE (goto_list, lookback[i]); - XFREE (lookback); + free (lookback); bitsetv_free (F); } -/*-----------------------------------------------------------. -| Count the number of lookaheads required for S (NLOOKAHEADS | -| member). | -`-----------------------------------------------------------*/ +/*-----------------------------------------------------. +| Count the number of look-ahead tokens required for S | +| (N_LOOK_AHEAD_TOKENS member). | +`-----------------------------------------------------*/ static int -state_lookaheads_count (state *s) +state_look_ahead_tokens_count (state *s) { int k; - int nlookaheads = 0; + int n_look_ahead_tokens = 0; reductions *rp = s->reductions; transitions *sp = s->transitions; - /* We need a lookahead either to distinguish different + /* We need a look-ahead either to distinguish different reductions (i.e., there are two or more), or to distinguish a reduction from a shift. Otherwise, it is straightforward, and the state is `consistent'. */ if (rp->num > 1 || (rp->num == 1 && sp->num && !TRANSITION_IS_DISABLED (sp, 0) && TRANSITION_IS_SHIFT (sp, 0))) - nlookaheads += rp->num; + n_look_ahead_tokens += rp->num; else s->consistent = 1; @@ -354,13 +363,13 @@ state_lookaheads_count (state *s) break; } - return nlookaheads; + return n_look_ahead_tokens; } -/*----------------------------------------------. -| Compute LA, NLA, and the lookaheads members. | -`----------------------------------------------*/ +/*-----------------------------------------------------. +| Compute LA, NLA, and the look_ahead_tokens members. | +`-----------------------------------------------------*/ static void initialize_LA (void) @@ -368,65 +377,65 @@ initialize_LA (void) state_number i; bitsetv pLA; - /* Compute the total number of reductions requiring a lookahead. */ + /* Compute the total number of reductions requiring a look-ahead. */ nLA = 0; for (i = 0; i < nstates; i++) - nLA += state_lookaheads_count (states[i]); + nLA += state_look_ahead_tokens_count (states[i]); /* Avoid having to special case 0. */ if (!nLA) nLA = 1; pLA = LA = bitsetv_create (nLA, ntokens, BITSET_FIXED); - lookback = XCALLOC (goto_list *, nLA); + lookback = xcalloc (nLA, sizeof *lookback); - /* Initialize the members LOOKAHEADS for each state which reductions - require lookaheads. */ + /* Initialize the members LOOK_AHEAD_TOKENS for each state whose reductions + require look-ahead tokens. */ for (i = 0; i < nstates; i++) { - int count = state_lookaheads_count (states[i]); + int count = state_look_ahead_tokens_count (states[i]); if (count) { - states[i]->reductions->lookaheads = pLA; + states[i]->reductions->look_ahead_tokens = pLA; pLA += count; } } } -/*---------------------------------------. -| Output the lookaheads for each state. | -`---------------------------------------*/ +/*----------------------------------------------. +| Output the look-ahead tokens for each state. | +`----------------------------------------------*/ static void -lookaheads_print (FILE *out) +look_ahead_tokens_print (FILE *out) { state_number i; int j, k; - fprintf (out, "Lookaheads: BEGIN\n"); + fprintf (out, "Look-ahead tokens: BEGIN\n"); for (i = 0; i < nstates; ++i) { reductions *reds = states[i]->reductions; bitset_iterator iter; - int nlookaheads = 0; + int n_look_ahead_tokens = 0; - if (reds->lookaheads) + if (reds->look_ahead_tokens) for (k = 0; k < reds->num; ++k) - if (reds->lookaheads[k]) - ++nlookaheads; + if (reds->look_ahead_tokens[k]) + ++n_look_ahead_tokens; - fprintf (out, "State %d: %d lookaheads\n", - i, nlookaheads); + fprintf (out, "State %d: %d look-ahead tokens\n", + i, n_look_ahead_tokens); - if (reds->lookaheads) + if (reds->look_ahead_tokens) for (j = 0; j < reds->num; ++j) - BITSET_FOR_EACH (iter, reds->lookaheads[j], k, 0) + BITSET_FOR_EACH (iter, reds->look_ahead_tokens[j], k, 0) { fprintf (out, " on %d (%s) -> rule %d\n", k, symbols[k]->tag, reds->rules[j]->number); }; } - fprintf (out, "Lookaheads: END\n"); + fprintf (out, "Look-ahead tokens: END\n"); } void @@ -437,10 +446,10 @@ lalr (void) initialize_F (); build_relations (); compute_FOLLOWS (); - compute_lookaheads (); + compute_look_ahead_tokens (); if (trace_flag & trace_sets) - lookaheads_print (stderr); + look_ahead_tokens_print (stderr); } @@ -449,6 +458,6 @@ lalr_free (void) { state_number s; for (s = 0; s < nstates; ++s) - states[s]->reductions->lookaheads = NULL; + states[s]->reductions->look_ahead_tokens = NULL; bitsetv_free (LA); }