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cex: display derivations as trees

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Sometimes, understanding the derivations is difficult, because they
are serialized to fit in one line.  For instance, the example taken
from the NEWS file:

    %token ID
    %%
    s: a ID
    a: expr
    expr: expr ID ',' | "expr"

gave

    First example        expr • ID ',' ID $end
    Shift derivation     $accept → [ s → [ a → [ expr → [ expr • ID ',' ] ] ID ] $end ]
    Second example       expr • ID $end
    Reduce derivation    $accept → [ s → [ a → [ expr • ] ID ] $end ]

Printing as trees, it gives:

    First example        expr • ID ',' ID $end
    Shift derivation
      $accept
      ↳ s                      $end
        ↳ a                 ID
          ↳ expr
            ↳ expr • ID ','
    Second example       expr • ID $end
    Reduce derivation
      $accept
      ↳ s             $end
        ↳ a        ID
          ↳ expr •

* src/glyphs.h, src/glyphs.c (down_arrow, empty, derivation_separator):
New.
* src/derivation.c (derivation_print, derivation_print_impl): Rename
as...
(derivation_print_flat, derivation_print_flat_impl): These.
(fputs_if, derivation_depth, derivation_width, derivation_print_tree)
(derivation_print_tree_impl, derivation_print): New.
* src/counterexample.c (print_counterexample): Adjust.
* tests/conflicts.at, tests/counterexample.at, tests/diagnostics.at,
* tests/report.at: Adjust.
This commit is contained in:
Akim Demaille
2020-07-14 08:16:16 +02:00
parent 5544615a59
commit fff17fe8fe
9 changed files with 986 additions and 72 deletions
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5
src/counterexample.c
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@@ -115,10 +115,11 @@ free_counterexample (counterexample *cex)
static void
print_counterexample (const counterexample *cex, FILE *out, const char *prefix)
{
const bool flat = getenv ("YYFLAT");
fprintf (out, " %s%-20s ",
prefix, cex->unifying ? _("Example") : _("First example"));
derivation_print_leaves (cex->d1, out, prefix);
fprintf (out, " %s%-20s ",
fprintf (out, flat ? " %s%-20s " : " %s%s",
prefix, cex->shift_reduce ? _("Shift derivation") : _("First derivation"));
derivation_print (cex->d1, out, prefix);
@@ -131,7 +132,7 @@ print_counterexample (const counterexample *cex, FILE *out, const char *prefix)
prefix, cex->unifying ? _("Example") : _("Second example"));
derivation_print_leaves (cex->d2, out, prefix);
}
fprintf (out, " %s%-20s ",
fprintf (out, flat ? " %s%-20s " : " %s%s",
prefix, cex->shift_reduce ? _("Reduce derivation") : _("Second derivation"));
derivation_print (cex->d2, out, prefix);