From: Akim Demaille <akim@epita.fr>
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 <akim@epita.fr>
+
+ 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 <akim@epita.fr>
* 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);