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New experimental feature: display the lookaheads in the report and

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graph.
* src/print (print_core): When --trace-flag, display the rules
lookaheads.
* src/print_graph.c (print_core): Likewise.
Swap the arguments.
Adjust caller.
This commit is contained in:
Akim Demaille
2002-05-05 11:56:49 +00:00
parent 39ceb25bdb
commit d4e7d3a191
4 changed files with 175 additions and 8 deletions
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11
ChangeLog
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@@ -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.

104
TODO
View File

@@ -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:

26
src/print.c
View File

@@ -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);
}

42
src/print_graph.c
View File

@@ -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);