Menhir handling

[Ninjapouet]

Following the PR #197, I suppose it would be nice to have a proper support to menhir as OCaml is often used DSL developments. I may suggest adding to package.toml something like

[menhir]
version = "X.Y"
tokens = {filename = "<filename>"; flags = "<flags>"}
parser = {filename = "<filename>"; flags = "<flags>"}

which would toggle the (use menhir "X.Y") in dune-project and generate the (menhir ...) stanzas according to the PR recommandations.

[lefessan]

In another project, I found:

dune-trailer = """(menhir (modules preproc_tokens grammar_common preproc_grammar)
        (merge_into preproc_grammar)
        (flags --table --external-tokens Preproc_tokens))
(menhir (modules preproc_tokens)
        (flags --only-tokens))
"""

[lefessan]

and worse:

(menhir (modules grammar_tokens grammar_common grammar)
        (merge_into grammar)
        (flags --inspection --cmly --table
	       --external-tokens Grammar_tokens
	       --unused-tokens))

(menhir (modules grammar_tokens)
        (flags --inspection --table --only-tokens))

(rule
  (targets text_keywords.ml)
  (enabled_if (<> %{profile} "release"))
  (deps    grammar.cmly)
  (mode    promote)
  (action
    (with-stdout-to %{targets}
       (run %{exe:./keywords/gen_keywords.exe} %{deps}
            --external-tokens Grammar_tokens))))

(rule
  (targets grammar_recover.ml)
  (enabled_if (<> %{profile} "release"))
  (deps    grammar.cmly)
  (mode    promote)
  (action
    (with-stdout-to %{targets}
       (run %{exe:./recover/gen_recover.exe} %{deps}))))

(rule
  (targets grammar_contexts.ml)
  (enabled_if (<> %{profile} "release"))
  (deps grammar.cmly)
  (mode promote)
  (action
    (with-stdout-to %{targets}
      (run %{exe:./context/gen_contexts.exe} %{deps}
        --external-tokens Grammar_tokens))))

(rule
  (targets grammar_context.ml)
  (enabled_if (<> %{profile} "release"))
  (deps    grammar.cmly)
  (mode    promote)
  (action
    (with-stdout-to %{targets}
       (run %{exe:./context/gen_context.exe} %{deps}))))

(rule
  (targets grammar_printer.ml)
  (enabled_if (<> %{profile} "release"))
  (deps    grammar.cmly)
  (mode    promote)
  (action
    (with-stdout-to %{targets}
       (run %{exe:./printer/gen_printer.exe} %{deps}))))

[lefessan]

Ok, the last rules are probably not really related to menhir itself, but use merlin stuff built for it...