X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/6a164e0c9619066b9d3f9e2401f68b602d4159e1..e91ff6ce3d2653b41265591dafd4bdb32ae114c2:/src/lalr.c?ds=sidebyside diff --git a/src/lalr.c b/src/lalr.c index b1188d64..643f8fd9 100644 --- a/src/lalr.c +++ b/src/lalr.c @@ -1,5 +1,6 @@ /* Compute look-ahead criteria for bison, - Copyright 1984, 1986, 1989, 2000, 2001 Free Software Foundation, Inc. + Copyright (C) 1984, 1986, 1989, 2000, 2001, 2002 + Free Software Foundation, Inc. This file is part of Bison, the GNU Compiler Compiler. @@ -24,33 +25,35 @@ tokens they accept. */ #include "system.h" +#include "bitset.h" +#include "bitsetv.h" +#include "quotearg.h" +#include "symtab.h" +#include "gram.h" +#include "reader.h" #include "types.h" #include "LR0.h" -#include "gram.h" #include "complain.h" #include "lalr.h" #include "nullable.h" #include "derives.h" #include "getargs.h" -/* All the decorated states, indexed by the state number. Warning: - there is a state_TABLE in LR0.c, but it is different and static. - */ -state_t **state_table = NULL; +/* All the decorated states, indexed by the state number. */ +state_t **states = NULL; -int tokensetsize; -short *LAruleno; -unsigned *LA; +rule_t **LArule = NULL; +bitsetv LA = NULL; +size_t nLA; static int ngotos; -short *goto_map; -short *from_state; -short *to_state; +short *goto_map = NULL; +short *from_state = NULL; +short *to_state = NULL; /* And for the famous F variable, which name is so descriptive that a comment is hardly needed. . */ -static unsigned *F = NULL; -#define F(Rule) (F + (Rule) * tokensetsize) +static bitsetv F = NULL; static short **includes; static shorts **lookback; @@ -73,9 +76,7 @@ static void traverse (int i) { int j; - size_t k; int height; - size_t size = F (i + 1) - F(i); VERTICES[++top] = i; INDEX[i] = height = top; @@ -89,8 +90,7 @@ traverse (int i) if (INDEX[i] > INDEX[R[i][j]]) INDEX[i] = INDEX[R[i][j]]; - for (k = 0; k < size; ++k) - F (i)[k] |= F (R[i][j])[k]; + bitset_or (F[i], F[i], F[R[i][j]]); } if (INDEX[i] == height) @@ -102,8 +102,7 @@ traverse (int i) if (i == j) break; - for (k = 0; k < size; ++k) - F (i)[k] = F (j)[k]; + bitset_copy (F[j], F[i]); } } @@ -135,37 +134,32 @@ digraph (short **relation) static void initialize_LA (void) { - int i; + size_t i; int j; - short *np; - reductions *rp; + rule_t **np; - size_t nLA = state_table[nstates]->lookaheads; + /* Avoid having to special case 0. */ if (!nLA) nLA = 1; - LA = XCALLOC (unsigned, nLA * tokensetsize); - LAruleno = XCALLOC (short, nLA); + LA = bitsetv_create (nLA, ntokens, BITSET_FIXED); + LArule = XCALLOC (rule_t *, nLA); lookback = XCALLOC (shorts *, nLA); - np = LAruleno; + np = LArule; for (i = 0; i < nstates; i++) - if (!state_table[i]->consistent) - if ((rp = state_table[i]->reductions)) - for (j = 0; j < rp->nreds; j++) - *np++ = rp->rules[j]; + if (!states[i]->consistent) + for (j = 0; j < states[i]->reductions->nreds; j++) + *np++ = &rules[states[i]->reductions->rules[j]]; } static void set_goto_map (void) { - int state; + size_t state; int i; - int symbol; - int k; short *temp_map; - int state2; goto_map = XCALLOC (short, nvars + 1) - ntokens; temp_map = XCALLOC (short, nvars + 1) - ntokens; @@ -173,49 +167,43 @@ set_goto_map (void) ngotos = 0; for (state = 0; state < nstates; ++state) { - shifts *sp = state_table[state]->shifts; + shifts *sp = states[state]->shifts; for (i = sp->nshifts - 1; i >= 0 && SHIFT_IS_GOTO (sp, i); --i) { - symbol = state_table[sp->shifts[i]]->accessing_symbol; - - if (ngotos == MAXSHORT) - fatal (_("too many gotos (max %d)"), MAXSHORT); + if (ngotos == SHRT_MAX) + fatal (_("too many gotos (max %d)"), SHRT_MAX); ngotos++; - goto_map[symbol]++; + goto_map[SHIFT_SYMBOL (sp, i)]++; } } - k = 0; - for (i = ntokens; i < nsyms; i++) - { - temp_map[i] = k; - k += goto_map[i]; - } + { + int k = 0; + for (i = ntokens; i < nsyms; i++) + { + temp_map[i] = k; + k += goto_map[i]; + } - for (i = ntokens; i < nsyms; i++) - goto_map[i] = temp_map[i]; + for (i = ntokens; i < nsyms; i++) + goto_map[i] = temp_map[i]; - goto_map[nsyms] = ngotos; - temp_map[nsyms] = ngotos; + goto_map[nsyms] = ngotos; + temp_map[nsyms] = ngotos; + } from_state = XCALLOC (short, ngotos); to_state = XCALLOC (short, ngotos); for (state = 0; state < nstates; ++state) { - shifts *sp = state_table[state]->shifts; + shifts *sp = states[state]->shifts; for (i = sp->nshifts - 1; i >= 0 && SHIFT_IS_GOTO (sp, i); --i) { - for (i = sp->nshifts - 1; i >= 0 && SHIFT_IS_GOTO (sp, i); --i) - { - state2 = sp->shifts[i]; - symbol = state_table[state2]->accessing_symbol; - - k = temp_map[symbol]++; - from_state[k] = state; - to_state[k] = state2; - } + int k = temp_map[SHIFT_SYMBOL (sp, i)]++; + from_state[k] = state; + to_state[k] = sp->shifts[i]; } } @@ -229,7 +217,7 @@ set_goto_map (void) `----------------------------------------------------------*/ static int -map_goto (int state, int symbol) +map_goto (int state, token_number_t symbol) { int high; int low; @@ -266,23 +254,20 @@ initialize_F (void) int i; - F = XCALLOC (unsigned, ngotos * tokensetsize); + F = bitsetv_create (ngotos, ntokens, BITSET_FIXED); for (i = 0; i < ngotos; i++) { int stateno = to_state[i]; - shifts *sp = state_table[stateno]->shifts; + shifts *sp = states[stateno]->shifts; int j; for (j = 0; j < sp->nshifts && SHIFT_IS_SHIFT (sp, j); j++) - { - int symbol = state_table[sp->shifts[j]]->accessing_symbol; - SETBIT (F (i), symbol); - } + bitset_set (F[i], SHIFT_SYMBOL (sp, j)); for (; j < sp->nshifts; j++) { - int symbol = state_table[sp->shifts[j]]->accessing_symbol; + token_number_t symbol = SHIFT_SYMBOL (sp, j); if (nullable[symbol]) edge[nedges++] = map_goto (stateno, symbol); } @@ -290,7 +275,7 @@ initialize_F (void) if (nedges) { reads[i] = XCALLOC (short, nedges + 1); - shortcpy (reads[i], edge, nedges); + memcpy (reads[i], edge, nedges * sizeof (edge[0])); reads[i][nedges] = -1; nedges = 0; } @@ -307,30 +292,21 @@ initialize_F (void) static void -add_lookback_edge (int stateno, int ruleno, int gotono) +add_lookback_edge (state_t *state, int ruleno, int gotono) { int i; - int k; - int found; shorts *sp; - i = state_table[stateno]->lookaheads; - k = state_table[stateno + 1]->lookaheads; - found = 0; - while (!found && i < k) - { - if (LAruleno[i] == ruleno) - found = 1; - else - i++; - } + for (i = 0; i < state->nlookaheads; ++i) + if (LArule[state->lookaheadsp + i]->number == ruleno) + break; - assert (found); + assert (LArule[state->lookaheadsp + i]->number == ruleno); sp = XCALLOC (shorts, 1); - sp->next = lookback[i]; + sp->next = lookback[state->lookaheadsp + i]; sp->value = gotono; - lookback[i] = sp; + lookback[state->lookaheadsp + i] = sp; } @@ -424,7 +400,7 @@ static void build_relations (void) { short *edge = XCALLOC (short, ngotos + 1); - short *states = XCALLOC (short, ritem_longest_rhs () + 1); + short *states1 = XCALLOC (short, ritem_longest_rhs () + 1); int i; includes = XCALLOC (short *, ngotos); @@ -432,34 +408,34 @@ build_relations (void) for (i = 0; i < ngotos; i++) { int nedges = 0; - int state1 = from_state[i]; - int symbol1 = state_table[to_state[i]]->accessing_symbol; + token_number_t symbol1 = states[to_state[i]]->accessing_symbol; short *rulep; for (rulep = derives[symbol1]; *rulep > 0; rulep++) { int done; int length = 1; - int stateno = state1; - short *rp; - states[0] = state1; + item_number_t *rp; + state_t *state = states[from_state[i]]; + states1[0] = state->number; - for (rp = ritem + rule_table[*rulep].rhs; *rp > 0; rp++) + for (rp = rules[*rulep].rhs; *rp >= 0; rp++) { - shifts *sp = state_table[stateno]->shifts; + shifts *sp = state->shifts; int j; for (j = 0; j < sp->nshifts; j++) { - stateno = sp->shifts[j]; - if (state_table[stateno]->accessing_symbol == *rp) + state = states[sp->shifts[j]]; + if (state->accessing_symbol + == item_number_as_token_number (*rp)) break; } - states[length++] = stateno; + states1[length++] = state->number; } - if (!state_table[stateno]->consistent) - add_lookback_edge (stateno, *rulep, i); + if (!state->consistent) + add_lookback_edge (state, *rulep, i); length--; done = 0; @@ -470,8 +446,9 @@ build_relations (void) /* JF added rp>=ritem && I hope to god its right! */ if (rp >= ritem && ISVAR (*rp)) { - stateno = states[--length]; - edge[nedges++] = map_goto (stateno, *rp); + /* Downcasting from item_number_t to token_number_t. */ + edge[nedges++] = map_goto (states1[--length], + item_number_as_token_number (*rp)); if (nullable[*rp]) done = 0; } @@ -489,7 +466,7 @@ build_relations (void) } XFREE (edge); - XFREE (states); + XFREE (states1); includes = transpose (includes, ngotos); } @@ -513,36 +490,98 @@ compute_FOLLOWS (void) static void compute_lookaheads (void) { - int i; + size_t i; shorts *sp; - for (i = 0; i < state_table[nstates]->lookaheads; i++) + for (i = 0; i < nLA; i++) for (sp = lookback[i]; sp; sp = sp->next) - { - int size = LA (i + 1) - LA (i); - int j; - for (j = 0; j < size; ++j) - LA (i)[j] |= F (sp->value)[j]; - } + bitset_or (LA[i], LA[i], F[sp->value]); /* Free LOOKBACK. */ - for (i = 0; i < state_table[nstates]->lookaheads; i++) + for (i = 0; i < nLA; i++) LIST_FREE (shorts, lookback[i]); XFREE (lookback); - XFREE (F); + bitsetv_free (F); } +/*--------------------------------------. +| Initializing the lookaheads members. | +`--------------------------------------*/ + +static void +initialize_lookaheads (void) +{ + size_t i; + nLA = 0; + for (i = 0; i < nstates; i++) + { + int k; + int nlookaheads = 0; + reductions *rp = states[i]->reductions; + shifts *sp = states[i]->shifts; + + /* 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->nreds > 1 + || (rp->nreds == 1 && sp->nshifts && SHIFT_IS_SHIFT (sp, 0))) + nlookaheads += rp->nreds; + else + states[i]->consistent = 1; + + for (k = 0; k < sp->nshifts; k++) + if (SHIFT_IS_ERROR (sp, k)) + { + states[i]->consistent = 0; + break; + } + + states[i]->nlookaheads = nlookaheads; + states[i]->lookaheadsp = nLA; + nLA += nlookaheads; + } +} + + +/*---------------------------------------. +| Output the lookaheads for each state. | +`---------------------------------------*/ + +static void +lookaheads_print (FILE *out) +{ + size_t i; + int j, k; + fprintf (out, "Lookaheads: BEGIN\n"); + for (i = 0; i < nstates; ++i) + { + fprintf (out, "State %d: %d lookaheads\n", + i, states[i]->nlookaheads); + + for (j = 0; j < states[i]->nlookaheads; ++j) + for (k = 0; k < ntokens; ++k) + if (bitset_test (LA[states[i]->lookaheadsp + j], k)) + fprintf (out, " on %d (%s) -> rule %d\n", + k, quotearg_style (escape_quoting_style, symbols[k]->tag), + LArule[states[i]->lookaheadsp + j]->number - 1); + } + fprintf (out, "Lookaheads: END\n"); +} + void lalr (void) { - tokensetsize = WORDSIZE (ntokens); - + initialize_lookaheads (); initialize_LA (); set_goto_map (); initialize_F (); build_relations (); compute_FOLLOWS (); compute_lookaheads (); + + if (trace_flag) + lookaheads_print (stderr); }