From: Akim Demaille Date: Sun, 5 May 2002 11:56:49 +0000 (+0000) Subject: New experimental feature: display the lookaheads in the report and X-Git-Tag: BISON-1_49b~238 X-Git-Url: https://git.saurik.com/bison.git/commitdiff_plain/d4e7d3a1919c20a6dbf5eb4cfa62cb6228a0e48d New experimental feature: display the lookaheads in the report and graph. * src/print (print_core): When --trace-flag, display the rules lookaheads. * src/print_graph.c (print_core): Likewise. Swap the arguments. Adjust caller. --- diff --git a/ChangeLog b/ChangeLog index d499bd3d..d49ff431 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,14 @@ +2002-05-05 Akim Demaille + + New experimental feature: display the lookaheads in the report and + graph. + + * src/print (print_core): When --trace-flag, display the rules + lookaheads. + * src/print_graph.c (print_core): Likewise. + Swap the arguments. + Adjust caller. + 2002-05-05 Akim Demaille * tests/torture.at (Many lookaheads): New test. diff --git a/TODO b/TODO index bc474d21..4780351f 100644 --- a/TODO +++ b/TODO @@ -21,6 +21,110 @@ When implementing multiple-%union support, bare the following in mind: char *sval; } +* Experimental report features +Decide whether they should be enabled, or optional. For instance, on: + + input: + exp + | input exp + ; + + exp: + token1 "1" + | token2 "2" + | token3 "3" + ; + + token1: token; + token2: token; + token3: token; + +the traditional Bison reports: + + state 0 + + $axiom -> . input $ (rule 0) + + token shift, and go to state 1 + + input go to state 2 + exp go to state 3 + token1 go to state 4 + token2 go to state 5 + token3 go to state 6 + + state 1 + + token1 -> token . (rule 6) + token2 -> token . (rule 7) + token3 -> token . (rule 8) + + "2" reduce using rule 7 (token2) + "3" reduce using rule 8 (token3) + $default reduce using rule 6 (token1) + +while with --trace, i.e., when enabling both the display of non-core +item sets and the display of lookaheads, Bison now displays: + + state 0 + + $axiom -> . input $ (rule 0) + input -> . exp (rule 1) + input -> . input exp (rule 2) + exp -> . token1 "1" (rule 3) + exp -> . token2 "2" (rule 4) + exp -> . token3 "3" (rule 5) + token1 -> . token (rule 6) + token2 -> . token (rule 7) + token3 -> . token (rule 8) + + token shift, and go to state 1 + + input go to state 2 + exp go to state 3 + token1 go to state 4 + token2 go to state 5 + token3 go to state 6 + + state 1 + + token1 -> token . ["1"] (rule 6) + token2 -> token . ["2"] (rule 7) + token3 -> token . ["3"] (rule 8) + + "2" reduce using rule 7 (token2) + "3" reduce using rule 8 (token3) + $default reduce using rule 6 (token1) + +so decide whether this should be an option, or always enabled. I'm in +favor of making it the default, but maybe we should tune the output to +distinguish core item sets from non core: + + state 0 + Core: + $axiom -> . input $ (rule 0) + + Derived: + input -> . exp (rule 1) + input -> . input exp (rule 2) + exp -> . token1 "1" (rule 3) + exp -> . token2 "2" (rule 4) + exp -> . token3 "3" (rule 5) + token1 -> . token (rule 6) + token2 -> . token (rule 7) + token3 -> . token (rule 8) + + token shift, and go to state 1 + + input go to state 2 + exp go to state 3 + token1 go to state 4 + token2 go to state 5 + token3 go to state 6 + + +Note that the same questions applies to --graph. + * Coding system independence Paul notes: diff --git a/src/print.c b/src/print.c index ec5a12ad..cfc047f1 100644 --- a/src/print.c +++ b/src/print.c @@ -105,6 +105,32 @@ print_core (FILE *out, state_t *state) for (/* Nothing */; *sp >= 0; ++sp) fprintf (out, " %s", escape (symbols[*sp]->tag)); + /* Experimental feature: display the lookaheads. */ + if (trace_flag && state->nlookaheads) + { + int j, k; + int nlookaheads = 0; + /* Look for lookaheads corresponding to this rule. */ + for (j = 0; j < state->nlookaheads; ++j) + for (k = 0; k < ntokens; ++k) + if (bitset_test (LA[state->lookaheadsp + j], k) + && LArule[state->lookaheadsp + j]->number == rule) + nlookaheads++; + if (nlookaheads) + { + fprintf (out, " ["); + for (j = 0; j < state->nlookaheads; ++j) + for (k = 0; k < ntokens; ++k) + if (bitset_test (LA[state->lookaheadsp + j], k) + && LArule[state->lookaheadsp + j]->number == rule) + fprintf (out, "%s%s", + quotearg_style (escape_quoting_style, + symbols[k]->tag), + --nlookaheads ? ", " : ""); + fprintf (out, "]"); + } + } + fprintf (out, _(" (rule %d)"), rule - 1); fputc ('\n', out); } diff --git a/src/print_graph.c b/src/print_graph.c index 15861f35..416c4fd2 100644 --- a/src/print_graph.c +++ b/src/print_graph.c @@ -47,7 +47,7 @@ escape (const char *s) /* This part will construct the label of nodes. */ static void -print_core (state_t *state, struct obstack *node_obstack) +print_core (struct obstack *oout, state_t *state) { int i; item_number_t *sitems = state->items; @@ -61,7 +61,7 @@ print_core (state_t *state, struct obstack *node_obstack) snritems = nritemset; } - obstack_fgrow1 (node_obstack, "state %2d\n", state->number); + obstack_fgrow1 (oout, "state %2d\n", state->number); for (i = 0; i < snritems; i++) { item_number_t *sp; @@ -76,17 +76,43 @@ print_core (state_t *state, struct obstack *node_obstack) rule = -(*sp); if (i) - obstack_1grow (node_obstack, '\n'); - obstack_fgrow1 (node_obstack, " %s -> ", + obstack_1grow (oout, '\n'); + obstack_fgrow1 (oout, " %s -> ", escape (rules[rule].lhs->tag)); for (sp = rules[rule].rhs; sp < sp1; sp++) - obstack_fgrow1 (node_obstack, "%s ", escape (symbols[*sp]->tag)); + obstack_fgrow1 (oout, "%s ", escape (symbols[*sp]->tag)); - obstack_1grow (node_obstack, '.'); + obstack_1grow (oout, '.'); for (/* Nothing */; *sp >= 0; ++sp) - obstack_fgrow1 (node_obstack, " %s", escape (symbols[*sp]->tag)); + obstack_fgrow1 (oout, " %s", escape (symbols[*sp]->tag)); + + /* Experimental feature: display the lookaheads. */ + if (trace_flag && state->nlookaheads) + { + int j, k; + int nlookaheads = 0; + /* Look for lookaheads corresponding to this rule. */ + for (j = 0; j < state->nlookaheads; ++j) + for (k = 0; k < ntokens; ++k) + if (bitset_test (LA[state->lookaheadsp + j], k) + && LArule[state->lookaheadsp + j]->number == rule) + nlookaheads++; + if (nlookaheads) + { + obstack_sgrow (oout, " ["); + for (j = 0; j < state->nlookaheads; ++j) + for (k = 0; k < ntokens; ++k) + if (bitset_test (LA[state->lookaheadsp + j], k) + && LArule[state->lookaheadsp + j]->number == rule) + obstack_fgrow2 (oout, "%s%s", + quotearg_style (escape_quoting_style, + symbols[k]->tag), + --nlookaheads ? ", " : ""); + obstack_sgrow (oout, "]"); + } + } } } @@ -154,7 +180,7 @@ print_state (state_t *state) new_node (&node); sprintf (name, "%d", state->number); node.title = name; - print_core (state, &node_obstack); + print_core (&node_obstack, state); obstack_1grow (&node_obstack, '\0'); node.label = obstack_finish (&node_obstack);