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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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12
src/glyphs.h
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@@ -31,4 +31,16 @@ extern int arrow_width;
extern const char *dot;
extern int dot_width;
/* "↳ ", below an lhs to announce the rhs. */
extern const char *down_arrow;
extern int down_arrow_width;
/* "ε", an empty rhs. */
extern const char *empty;
extern int empty_width;
/* " ", separate symbols in the rhs of a derivation. */
extern const char *derivation_separator;
extern int derivation_separator_width;
#endif /* GLYPHS_H */