File ‹Code/code_simp.ML›

(*  Title:      Tools/Code/code_simp.ML
    Author:     Florian Haftmann, TU Muenchen

Connecting the simplifier and the code generator.
*)

signature CODE_SIMP =
sig
  val map_ss: (Proof.context -> Proof.context) -> theory -> theory
  val dynamic_conv: Proof.context -> conv
  val dynamic_tac: Proof.context -> int -> tactic
  val dynamic_value: Proof.context -> term -> term
  val static_conv: { ctxt: Proof.context, simpset: simpset option, consts: string list }
    -> Proof.context -> conv
  val static_tac: { ctxt: Proof.context, simpset: simpset option, consts: string list }
    -> Proof.context -> int -> tactic
  val trace: bool Config.T
end;

structure Code_Simp : CODE_SIMP =
struct

(* dedicated simpset *)

structure Simpset = Theory_Data
(
  type T = simpset;
  val empty = empty_ss;
  val merge = merge_ss;
);

fun map_ss f thy =
  Simpset.map (simpset_map (Proof_Context.init_global thy) f) thy;

fun simpset_default ctxt some_ss =
  the_default (Simpset.get (Proof_Context.theory_of ctxt)) some_ss;


(* diagnostic *)

val trace = Attrib.setup_config_bool \<^binding>‹code_simp_trace› (K false);

fun set_trace ctxt =
  let
    val global = Config.get ctxt trace;
  in
    ctxt |> Config.map Simplifier.simp_trace (fn b => b orelse global)
  end;


(* build simpset context and conversion from program *)

fun add_stmt (Code_Thingol.Fun ((_, eqs), some_cong)) ss =
      ss
      |> fold Simplifier.add_simp ((map_filter (fst o snd)) eqs)
      |> fold Simplifier.add_cong (the_list some_cong)
  | add_stmt (Code_Thingol.Classinst { inst_params, ... }) ss =
      ss
      |> fold Simplifier.add_simp (map (fst o snd) inst_params)
  | add_stmt _ ss = ss;

val add_program = Code_Symbol.Graph.fold (add_stmt o fst o snd);

val simpset_program =
  Code_Preproc.timed "building simpset" #ctxt
  (fn { ctxt, some_ss, program } => simpset_map ctxt (add_program program) (simpset_default ctxt some_ss));

fun rewrite_modulo ctxt some_ss program =
  let
    val ss = simpset_program
      { ctxt = ctxt, some_ss = some_ss, program = program };
  in fn ctxt => 
    Code_Preproc.timed_conv "simplifying"
      Simplifier.full_rewrite (ctxt |> put_simpset ss |> set_trace)
  end;

fun conclude_tac ctxt some_ss =
  let
    val ss = simpset_default ctxt some_ss
  in fn ctxt => Simplifier.full_simp_tac (ctxt |> put_simpset ss) end;


(* evaluation with dynamic code context *)

fun dynamic_conv ctxt = Code_Thingol.dynamic_conv ctxt
  (fn program => fn _ => fn _ => rewrite_modulo ctxt NONE program ctxt);

fun dynamic_tac ctxt = CONVERSION (dynamic_conv ctxt)
  THEN' conclude_tac ctxt NONE ctxt;

fun dynamic_value ctxt =
  snd o Logic.dest_equals o Thm.prop_of o dynamic_conv ctxt o Thm.cterm_of ctxt;

val _ = Theory.setup 
  (Method.setup \<^binding>‹code_simp›
    (Scan.succeed (SIMPLE_METHOD' o (CHANGED_PROP oo dynamic_tac)))
    "simplification with code equations");


(* evaluation with static code context *)

fun static_conv { ctxt, simpset, consts } =
  Code_Thingol.static_conv_isa { ctxt = ctxt, consts = consts }
    (fn program => let
       val conv = rewrite_modulo ctxt simpset program
     in fn ctxt => fn _ => conv ctxt end);

fun static_tac { ctxt, simpset, consts } =
  let
    val conv = static_conv { ctxt = ctxt, simpset = simpset, consts = consts };
    val tac = conclude_tac ctxt simpset;
  in fn ctxt' => CONVERSION (conv ctxt') THEN' (tac ctxt') end;

end;