X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/8b752b00fdaaa3802e4ab05a468f6cda4a9fa500..6175ffe3211dad578ce6585584c4eb85cf891830:/src/lalr.c diff --git a/src/lalr.c b/src/lalr.c index d735921a..4e59d0ad 100644 --- a/src/lalr.c +++ b/src/lalr.c @@ -1,4 +1,5 @@ -/* Compute look-ahead criteria for bison, +/* Compute look-ahead criteria for Bison. + Copyright (C) 1984, 1986, 1989, 2000, 2001, 2002 Free Software Foundation, Inc. @@ -25,84 +26,74 @@ tokens they accept. */ #include "system.h" -#include "bitset.h" -#include "bitsetv.h" -#include "relation.h" -#include "quotearg.h" -#include "symtab.h" -#include "gram.h" -#include "reader.h" -#include "types.h" + +#include +#include +#include + #include "LR0.h" #include "complain.h" -#include "lalr.h" -#include "nullable.h" #include "derives.h" #include "getargs.h" +#include "gram.h" +#include "lalr.h" +#include "nullable.h" +#include "reader.h" +#include "relation.h" +#include "symtab.h" -rule_t **LArule = NULL; -bitsetv LA = NULL; -size_t nLA; - -static int ngotos; -short *goto_map = NULL; -state_number_t *from_state = NULL; -state_number_t *to_state = NULL; +goto_number *goto_map = NULL; +static goto_number ngotos = 0; +state_number *from_state = NULL; +state_number *to_state = NULL; -/* And for the famous F variable, which name is so descriptive that a - comment is hardly needed. . */ -static bitsetv F = NULL; +/* Linked list of goto numbers. */ +typedef struct goto_list +{ + struct goto_list *next; + goto_number value; +} goto_list; -static short **includes; -static shorts **lookback; +/* LA is a LR by NTOKENS matrix of bits. LA[l, i] is 1 if the rule + LArule[l] is applicable in the appropriate state when the next + token is symbol i. If LA[l, i] and LA[l, j] are both 1 for i != j, + it is a conflict. */ +static bitsetv LA = NULL; +size_t nLA; -static void -initialize_LA (void) -{ - state_number_t i; - int j; - rule_t **np; +/* And for the famous F variable, which name is so descriptive that a + comment is hardly needed. . */ +static bitsetv F = NULL; - /* Avoid having to special case 0. */ - if (!nLA) - nLA = 1; +static goto_number **includes; +static goto_list **lookback; - LA = bitsetv_create (nLA, ntokens, BITSET_FIXED); - LArule = XCALLOC (rule_t *, nLA); - lookback = XCALLOC (shorts *, nLA); - np = LArule; - for (i = 0; i < nstates; i++) - if (!states[i]->consistent) - for (j = 0; j < states[i]->reductions->num; j++) - *np++ = &rules[states[i]->reductions->rules[j]]; -} static void set_goto_map (void) { - state_number_t state; - short *temp_map; + state_number s; + goto_number *temp_map; - goto_map = XCALLOC (short, nvars + 1) - ntokens; - temp_map = XCALLOC (short, nvars + 1) - ntokens; + CALLOC (goto_map, nvars + 1); + CALLOC (temp_map, nvars + 1); ngotos = 0; - for (state = 0; state < nstates; ++state) + for (s = 0; s < nstates; ++s) { - transitions_t *sp = states[state]->transitions; + transitions *sp = states[s]->transitions; int i; for (i = sp->num - 1; i >= 0 && TRANSITION_IS_GOTO (sp, i); --i) { - if (ngotos == SHRT_MAX) - fatal (_("too many gotos (max %d)"), SHRT_MAX); - + if (ngotos >= GOTO_NUMBER_MAXIMUM) + abort (); ngotos++; - goto_map[TRANSITION_SYMBOL (sp, i)]++; + goto_map[TRANSITION_SYMBOL (sp, i) - ntokens]++; } } @@ -111,33 +102,33 @@ set_goto_map (void) 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_t, ngotos); - to_state = XCALLOC (state_number_t, ngotos); + CALLOC (from_state, ngotos); + CALLOC (to_state, ngotos); - for (state = 0; state < nstates; ++state) + for (s = 0; s < nstates; ++s) { - transitions_t *sp = states[state]->transitions; + transitions *sp = states[s]->transitions; int i; for (i = sp->num - 1; i >= 0 && TRANSITION_IS_GOTO (sp, i); --i) { - int k = temp_map[TRANSITION_SYMBOL (sp, i)]++; - from_state[k] = state; - to_state[k] = sp->states[i]; + int k = temp_map[TRANSITION_SYMBOL (sp, i) - ntokens]++; + from_state[k] = s; + to_state[k] = sp->states[i]->number; } } - XFREE (temp_map + ntokens); + XFREE (temp_map); } @@ -147,39 +138,37 @@ set_goto_map (void) `----------------------------------------------------------*/ static int -map_goto (state_number_t state, symbol_number_t symbol) +map_goto (state_number s0, symbol_number sym) { int high; int low; int middle; - state_number_t s; + state_number s; - low = goto_map[symbol]; - high = goto_map[symbol + 1] - 1; + low = goto_map[sym - ntokens]; + high = goto_map[sym - ntokens + 1] - 1; - while (low <= high) + for (;;) { + if (high < low) + abort (); middle = (low + high) / 2; s = from_state[middle]; - if (s == state) + if (s == s0) return middle; - else if (s < state) + else if (s < s0) low = middle + 1; else high = middle - 1; } - - assert (0); - /* NOTREACHED */ - return 0; } static void initialize_F (void) { - short **reads = XCALLOC (short *, ngotos); - short *edge = XCALLOC (short, ngotos + 1); + goto_number **reads = CALLOC (reads, ngotos); + goto_number *edge = CALLOC (edge, ngotos + 1); int nedges = 0; int i; @@ -188,23 +177,23 @@ initialize_F (void) for (i = 0; i < ngotos; i++) { - state_number_t stateno = to_state[i]; - transitions_t *sp = states[stateno]->transitions; + state_number stateno = to_state[i]; + transitions *sp = states[stateno]->transitions; int j; - for (j = 0; j < sp->num && TRANSITION_IS_SHIFT (sp, j); j++) + FOR_EACH_SHIFT (sp, j) bitset_set (F[i], TRANSITION_SYMBOL (sp, j)); for (; j < sp->num; j++) { - symbol_number_t symbol = TRANSITION_SYMBOL (sp, j); - if (nullable[symbol]) - edge[nedges++] = map_goto (stateno, symbol); + symbol_number sym = TRANSITION_SYMBOL (sp, j); + if (nullable[sym - ntokens]) + edge[nedges++] = map_goto (stateno, sym); } if (nedges) { - reads[i] = XCALLOC (short, nedges + 1); + CALLOC (reads[i], nedges + 1); memcpy (reads[i], edge, nedges * sizeof (edge[0])); reads[i][nedges] = -1; nedges = 0; @@ -222,21 +211,13 @@ initialize_F (void) static void -add_lookback_edge (state_t *state, rule_number_t ruleno, int gotono) +add_lookback_edge (state *s, rule *r, int gotono) { - int i; - shorts *sp; - - for (i = 0; i < state->nlookaheads; ++i) - if (state->lookaheads_rule[i]->number == ruleno) - break; - - assert (state->lookaheads_rule[i]->number == ruleno); - - sp = XCALLOC (shorts, 1); - sp->next = lookback[(state->lookaheads - LA) + i]; + int ri = state_reduction_find (s, r); + goto_list *sp = MALLOC (sp, 1); + sp->next = lookback[(s->reductions->lookaheads - LA) + ri]; sp->value = gotono; - lookback[(state->lookaheads - LA) + i] = sp; + lookback[(s->reductions->lookaheads - LA) + ri] = sp; } @@ -244,35 +225,35 @@ add_lookback_edge (state_t *state, rule_number_t ruleno, int gotono) static void build_relations (void) { - short *edge = XCALLOC (short, ngotos + 1); - state_number_t *states1 = XCALLOC (state_number_t, ritem_longest_rhs () + 1); + goto_number *edge = CALLOC (edge, ngotos + 1); + state_number *states1 = CALLOC (states1, ritem_longest_rhs () + 1); int i; - includes = XCALLOC (short *, ngotos); + CALLOC (includes, ngotos); for (i = 0; i < ngotos; i++) { int nedges = 0; - symbol_number_t symbol1 = states[to_state[i]]->accessing_symbol; - rule_number_t *rulep; + symbol_number symbol1 = states[to_state[i]]->accessing_symbol; + rule **rulep; - for (rulep = derives[symbol1]; *rulep > 0; rulep++) + for (rulep = derives[symbol1 - ntokens]; *rulep; rulep++) { int done; int length = 1; - item_number_t *rp; - state_t *state = states[from_state[i]]; - states1[0] = state->number; + item_number *rp; + state *s = states[from_state[i]]; + states1[0] = s->number; - for (rp = rules[*rulep].rhs; *rp >= 0; rp++) + for (rp = (*rulep)->rhs; *rp >= 0; rp++) { - state = transitions_to (state->transitions, - item_number_as_symbol_number (*rp)); - states1[length++] = state->number; + s = transitions_to (s->transitions, + item_number_as_symbol_number (*rp)); + states1[length++] = s->number; } - if (!state->consistent) - add_lookback_edge (state, *rulep, i); + if (!s->consistent) + add_lookback_edge (s, *rulep, i); length--; done = 0; @@ -283,10 +264,10 @@ build_relations (void) /* JF added rp>=ritem && I hope to god its right! */ if (rp >= ritem && ISVAR (*rp)) { - /* Downcasting from item_number_t to symbol_number_t. */ + /* Downcasting from item_number to symbol_number. */ edge[nedges++] = map_goto (states1[--length], item_number_as_symbol_number (*rp)); - if (nullable[*rp]) + if (nullable[*rp - ntokens]) done = 0; } } @@ -295,7 +276,7 @@ build_relations (void) if (nedges) { int j; - includes[i] = XCALLOC (short, nedges + 1); + CALLOC (includes[i], nedges + 1); for (j = 0; j < nedges; j++) includes[i][j] = edge[j]; includes[i][nedges] = -1; @@ -328,7 +309,7 @@ static void compute_lookaheads (void) { size_t i; - shorts *sp; + goto_list *sp; for (i = 0; i < nLA; i++) for (sp = lookback[i]; sp; sp = sp->next) @@ -336,74 +317,79 @@ compute_lookaheads (void) /* Free LOOKBACK. */ for (i = 0; i < nLA; i++) - LIST_FREE (shorts, lookback[i]); + LIST_FREE (goto_list, lookback[i]); XFREE (lookback); bitsetv_free (F); } -/*-------------------------------------------------------------. -| Count the number of lookaheads required for each state | -| (NLOOKAHEADS member). Compute the total number of LA, NLA. | -`-------------------------------------------------------------*/ +/*-----------------------------------------------------------. +| Count the number of lookaheads required for S (NLOOKAHEADS | +| member). | +`-----------------------------------------------------------*/ -static void -states_lookaheads_count (void) +static int +state_lookaheads_count (state *s) { - state_number_t i; - nLA = 0; - - /* Count */ - for (i = 0; i < nstates; i++) - { - int k; - int nlookaheads = 0; - reductions_t *rp = states[i]->reductions; - transitions_t *sp = states[i]->transitions; - - /* We need a lookahead 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_SHIFT (sp, 0))) - nlookaheads += rp->num; - else - states[i]->consistent = 1; - - for (k = 0; k < sp->num; k++) - if (TRANSITION_IS_ERROR (sp, k)) - { - states[i]->consistent = 0; - break; - } + int k; + int nlookaheads = 0; + reductions *rp = s->reductions; + transitions *sp = s->transitions; + + /* We need a lookahead 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; + else + s->consistent = 1; + + for (k = 0; k < sp->num; k++) + if (!TRANSITION_IS_DISABLED (sp, k) && TRANSITION_IS_ERROR (sp, k)) + { + s->consistent = 0; + break; + } - states[i]->nlookaheads = nlookaheads; - nLA += nlookaheads; - } + return nlookaheads; } -/*--------------------------------------. -| Initializing the lookaheads members. | -`--------------------------------------*/ +/*----------------------------------------------. +| Compute LA, NLA, and the lookaheads members. | +`----------------------------------------------*/ static void -states_lookaheads_initialize (void) +initialize_LA (void) { - state_number_t i; - bitsetv pLA = LA; - rule_t **pLArule = LArule; + state_number i; + bitsetv pLA; - /* Initialize the members LOOKAHEADS and LOOKAHEADS_RULE for each - state. */ + /* Compute the total number of reductions requiring a lookahead. */ + nLA = 0; + for (i = 0; i < nstates; i++) + nLA += state_lookaheads_count (states[i]); + /* Avoid having to special case 0. */ + if (!nLA) + nLA = 1; + + pLA = LA = bitsetv_create (nLA, ntokens, BITSET_FIXED); + CALLOC (lookback, nLA); + + /* Initialize the members LOOKAHEADS for each state which reductions + require lookaheads. */ for (i = 0; i < nstates; i++) { - states[i]->lookaheads = pLA; - states[i]->lookaheads_rule = pLArule; - pLA += states[i]->nlookaheads; - pLArule += states[i]->nlookaheads; + int count = state_lookaheads_count (states[i]); + if (count) + { + states[i]->reductions->lookaheads = pLA; + pLA += count; + } } } @@ -415,23 +401,31 @@ states_lookaheads_initialize (void) static void lookaheads_print (FILE *out) { - state_number_t i; + state_number i; int j, k; fprintf (out, "Lookaheads: BEGIN\n"); for (i = 0; i < nstates; ++i) { + reductions *reds = states[i]->reductions; bitset_iterator iter; + int nlookaheads = 0; + + if (reds->lookaheads) + for (k = 0; k < reds->num; ++k) + if (reds->lookaheads[k]) + ++nlookaheads; fprintf (out, "State %d: %d lookaheads\n", - i, states[i]->nlookaheads); + i, nlookaheads); - for (j = 0; j < states[i]->nlookaheads; ++j) - BITSET_FOR_EACH (iter, states[i]->lookaheads[j], k, 0) - { - fprintf (out, " on %d (%s) -> rule %d\n", - k, symbols[k]->tag, - states[i]->lookaheads_rule[j]->number - 1); - }; + if (reds->lookaheads) + for (j = 0; j < reds->num; ++j) + BITSET_FOR_EACH (iter, reds->lookaheads[j], k, 0) + { + fprintf (out, " on %d (%s) -> rule %d\n", + k, symbols[k]->tag, + reds->rules[j]->number); + }; } fprintf (out, "Lookaheads: END\n"); } @@ -439,15 +433,23 @@ lookaheads_print (FILE *out) void lalr (void) { - states_lookaheads_count (); initialize_LA (); - states_lookaheads_initialize (); set_goto_map (); initialize_F (); build_relations (); compute_FOLLOWS (); compute_lookaheads (); - if (trace_flag) + if (trace_flag & trace_sets) lookaheads_print (stderr); } + + +void +lalr_free (void) +{ + state_number s; + for (s = 0; s < nstates; ++s) + states[s]->reductions->lookaheads = NULL; + bitsetv_free (LA); +}