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evaluator.ml
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evaluator.ml
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open Types
type eval_state = Stable | Changed
let delta_reduction (ast : abstract_tree) =
let (astmain, layer) = ast in
match astmain with
| Apply((Apply((PermContentOf("+"), _), (IntConst(ic1), _)), _), (IntConst(ic2), _)) -> (Changed, (IntConst(ic1 + ic2), layer))
| Apply((Apply((PermContentOf("-"), _), (IntConst(ic1), _)), _), (IntConst(ic2), _)) -> (Changed, (IntConst(ic1 - ic2), layer))
| Apply((Apply((PermContentOf("*"), _), (IntConst(ic1), _)), _), (IntConst(ic2), _)) -> (Changed, (IntConst(ic1 * ic2), layer))
| Apply((Apply((PermContentOf("/"), _), (IntConst(ic1), _)), _), (IntConst(ic2), _)) -> (Changed, (IntConst(ic1 / ic2), layer))
| Apply((Apply((PermContentOf("=="), _), (IntConst(ic1), _)), _), (IntConst(ic2), _)) -> (Changed, (BoolConst(ic1 == ic2), layer))
| Apply((Apply((PermContentOf(">="), _), (IntConst(ic1), _)), _), (IntConst(ic2), _)) -> (Changed, (BoolConst(ic1 >= ic2), layer))
| Apply((Apply((PermContentOf("<="), _), (IntConst(ic1), _)), _), (IntConst(ic2), _)) -> (Changed, (BoolConst(ic1 <= ic2), layer))
| Apply((Apply((PermContentOf(">"), _), (IntConst(ic1), _)), _), (IntConst(ic2), _)) -> (Changed, (BoolConst(ic1 > ic2), layer))
| Apply((Apply((PermContentOf("<"), _), (IntConst(ic1), _)), _), (IntConst(ic2), _)) -> (Changed, (BoolConst(ic1 < ic2), layer))
| Apply((Apply((PermContentOf("&&"), _), (BoolConst(bc1), _)), _), (BoolConst(bc2), _)) -> (Changed, (BoolConst(bc1 && bc2), layer))
| Apply((Apply((PermContentOf("||"), _), (BoolConst(bc1), _)), _), (BoolConst(bc2), _)) -> (Changed, (BoolConst(bc1 || bc2), layer))
| _ -> (Stable, ast)
let rec replace (ast1 : abstract_tree) (varnm : variable_name) (ast2 : abstract_tree) =
let iter ast = replace ast varnm ast2 in
let (astmain1, layer) = ast1 in
match astmain1 with
| OrdContentOf(ovnm) when ovnm = varnm -> ast2
| OrdContentOf(_) -> ast1
| PermContentOf(pvnm) when pvnm = varnm -> ast2
| PermContentOf(_) -> ast1
| Apply(sub1, sub2) -> (Apply(iter sub1, iter sub2), layer)
| Lambda(ovnm, sub1) when ovnm = varnm -> ast1
| Lambda(ovnm, sub1) -> (Lambda(ovnm, iter sub1), layer)
| FixPoint(ovnm, sub1) when ovnm = varnm -> ast1
| FixPoint(ovnm, sub1) -> (FixPoint(ovnm, iter sub1), layer)
| IfThenElse(sub0, sub1, sub2) -> (IfThenElse(iter sub0, iter sub1, iter sub2), layer)
| Next(sub1) -> (Next(iter sub1), layer)
| Prev(sub1) -> (Prev(iter sub1), layer)
| Box(sub1) -> (Box(iter sub1), layer)
| Unbox(pvnm, i, sub1, sub2) when pvnm = varnm -> (Unbox(pvnm, i, iter sub1, sub2), layer)
| Unbox(pvnm, i, sub1, sub2) -> (Unbox(pvnm, i, iter sub1, iter sub2), layer)
| IntConst(_) -> ast1
| BoolConst(_) -> ast1
let rec emerge_free (varnm : variable_name) (ast : abstract_tree) =
let iter = emerge_free varnm in
let (astmain, _) = ast in
match astmain with
| OrdContentOf(ovnm) -> ovnm = varnm
| PermContentOf(pvnm) -> pvnm = varnm
| Apply(ast1, ast2) -> (iter ast1) || (iter ast2)
| Lambda(ovnm, ast1) when ovnm = varnm -> false
| Lambda(_, ast1) -> iter ast1
| FixPoint(ovnm, ast1) when ovnm = varnm -> false
| FixPoint(_, ast1) -> iter ast1
| IfThenElse(ast0, ast1, ast2) -> (iter ast0) || (iter ast1) || (iter ast2)
| Next(ast1) -> iter ast1
| Prev(ast1) -> iter ast1
| Box(ast1) -> iter ast1
| Unbox(pvnm, _, ast1, ast2) when pvnm = varnm -> iter ast1
| Unbox(_, _, ast1, ast2) -> (iter ast1) || (iter ast2)
| IntConst(_) -> false
| BoolConst(_) -> false
let rec collect_free_variable (ast : abstract_tree) =
let iter = collect_free_variable in
let omit varnm = List.filter (fun v -> v <> varnm) in
let (astmain, _) = ast in
match astmain with
| OrdContentOf(ovnm) -> [ovnm]
| PermContentOf(pvnm) -> [pvnm]
| Apply(ast1, ast2) -> List.append (iter ast1) (iter ast2)
| Lambda(ovnm, ast1) -> omit ovnm (iter ast1)
| FixPoint(ovnm, ast1) -> omit ovnm (iter ast1)
| IfThenElse(ast0, ast1, ast2) -> List.concat [(iter ast0); (iter ast1); (iter ast2)]
| Next(ast1) -> iter ast1
| Prev(ast1) -> iter ast1
| Box(ast1) -> iter ast1
| Unbox(pvnm, _, ast1, ast2) -> List.append (iter ast1) (omit pvnm (iter ast2))
| IntConst(_) -> []
| BoolConst(_) -> []
let fresh_variable_id : int ref = ref 0
let initialize () =
fresh_variable_id := 0
let fresh_variable_name () =
let resnm = "_symb" ^ (string_of_int !fresh_variable_id) in
begin
fresh_variable_id := !fresh_variable_id + 1 ;
resnm
end
let rec alpha_renaming (prohiblst : variable_name list) (ast : abstract_tree) =
let iter = alpha_renaming prohiblst in
let (astmain, layer) = ast in
match astmain with
| OrdContentOf(_) -> ast
| PermContentOf(_) -> ast
| Apply(ast1, ast2) -> (Apply(iter ast1, iter ast2), layer)
| Lambda(ovnm, ast1)
when List.mem ovnm prohiblst ->
let ovnmnew = fresh_variable_name () in
let ast1new = replace ast1 ovnm (OrdContentOf(ovnmnew), layer) in
(Lambda(ovnmnew, iter ast1new), layer)
| Lambda(ovnm, ast1) -> (Lambda(ovnm, iter ast1), layer)
| FixPoint(ovnm, ast1)
when List.mem ovnm prohiblst ->
let ovnmnew = fresh_variable_name () in
let ast1new = replace ast1 ovnm (OrdContentOf(ovnmnew), layer) in
(FixPoint(ovnmnew, iter ast1new), layer)
| FixPoint(ovnm, ast1) -> (FixPoint(ovnm, iter ast1), layer)
| IfThenElse(ast0, ast1, ast2) -> (IfThenElse(iter ast0, iter ast1, iter ast2), layer)
| Next(ast1) -> (Next(iter ast1), layer)
| Prev(ast1) -> (Prev(iter ast1), layer)
| Box(ast1) -> (Box(iter ast1), layer)
| Unbox(pvnm, i, ast1, ast2) -> (Unbox(pvnm, i, iter ast1, iter ast2), layer)
| IntConst(_) -> ast
| BoolConst(_) -> ast
let rec beta_reduction (ast1 : abstract_tree) (varnm : variable_name) (ast2 : abstract_tree) =
let freevarlst = collect_free_variable ast2 in
let ast1new = alpha_renaming freevarlst ast1 in
replace ast1new varnm ast2
let rec eval (evlayer : int) (ast : abstract_tree) =
let (astmain, layer) = ast in
match astmain with
(* -- values -- *)
| OrdContentOf(_) -> (Stable, ast)
| PermContentOf(_) -> (Stable, ast)
| IntConst(_) -> (Stable, ast)
| BoolConst(_) -> (Stable, ast)
(* -- non-values -- *)
| Lambda(ovnm, ast1) ->
if evlayer = layer then
(Stable, ast)
else if evlayer > layer then
(Stable, ast)
else (* if evlayer < layer *)
let (state1, res1) = eval evlayer ast1 in
(state1, (Lambda(ovnm, res1), layer))
| FixPoint(ovnm, ast1) ->
if evlayer = layer then
begin print_for_debug "****FIX1****" ; (* test *)
(Changed, beta_reduction ast1 ovnm ast)
end (* test *)
else if evlayer > layer then
begin print_for_debug "****FIX2****" ; (* test *)
(Stable, ast)
end (* test *)
else (* if evlayer < layer *)
begin print_for_debug "****FIX3****" ; (* test *)
let (state1, res1) = eval evlayer ast1 in
(state1, (FixPoint(ovnm, res1), layer))
end(* test *)
| IfThenElse(ast0, ast1, ast2) ->
if evlayer = layer then
let (state0, res0) = eval evlayer ast0 in
begin
match (state0, res0) with
| (Changed, _) -> (Changed, (IfThenElse(res0, ast1, ast2), layer))
| (Stable, (BoolConst(true), _)) -> (Changed, ast1)
| (Stable, (BoolConst(false), _)) -> (Changed, ast2)
| (Stable, _) -> assert false
end
else if evlayer > layer then
(Stable, ast)
else (* if evlayer < layer *)
let (state1, res1) = eval evlayer ast1 in
begin
match state1 with
| Changed -> (Changed, (IfThenElse(ast0, res1, ast2), layer))
| Stable ->
let (state2, res2) = eval evlayer ast2 in
(state2, (IfThenElse(ast0, res1, res2), layer))
end
| Next(ast1) ->
let (state1, res1) = eval evlayer ast1 in
(state1, (Next(res1), layer))
| Prev(ast1) ->
let (state1, res1) = eval evlayer ast1 in
begin
match (state1, res1) with
| (Changed, _) -> (Changed, (Prev(res1), layer))
| (Stable, (Next(res1sub), layer1)) when layer1 = evlayer -> (Changed, res1sub)
| (Stable, (Unbox(pvnm, i, ast1, ast2), _)) -> (Changed, (Unbox(pvnm, i - 1, ast1, (Prev(ast2), layer)), layer))
| (Stable, _) -> (Stable, (Prev(res1), layer))
end
| Box(ast1) ->
let (state1, res1) = eval evlayer ast1 in
(state1, (Box(res1), layer))
| Unbox(pvnm, i, ast1, ast2) ->
if evlayer = layer then
let (state1, res1) = eval evlayer ast1 in
begin
match (state1, res1) with
| (Changed, _) -> (Changed, (Unbox(pvnm, i, res1, ast2), layer))
| (Stable, (Box(res1sub), _)) -> (Changed, replace ast2 pvnm res1sub)
| (Stable, (Unbox(pvnm1, j, ast11, ast12), _))
when not (emerge_free pvnm1 ast2) -> (Changed, (Unbox(pvnm1, i + j, ast11, (Unbox(pvnm, i, ast12, ast2), layer)), layer))
| (Stable, _) ->
let (state2, res2) = eval evlayer ast2 in
(state2, (Unbox(pvnm, i, res1, res2), layer))
end
else if evlayer > layer then
(Stable, ast)
else (* if evlayer < layer *)
let (state1, res1) = eval evlayer ast1 in
begin
match state1 with
| Changed -> (Changed, (Unbox(pvnm, i, res1, ast2), layer))
| Stable ->
let (state2, res2) = eval evlayer ast2 in
(state2, (Unbox(pvnm, i, res1, res2), layer))
end
| Apply(ast1, ast2) ->
if evlayer = layer then
begin print_for_debug "****APPLY1****" ; (* test *)
print_for_debug ("** " ^ (string_of_abstract_tree ast1)) ; (* test *)
print_for_debug ("** " ^ (string_of_abstract_tree ast2)) ; (* test *)
let (state1, res1) = eval evlayer ast1 in
begin
match state1 with
| Changed -> (Changed, (Apply(res1, ast2), layer))
| Stable ->
let (state2, res2) = eval evlayer ast2 in
begin
match state2 with
| Changed -> (Changed, (Apply(res1, res2), layer))
| Stable ->
begin
match res1 with
| (Lambda(ovnm, ast1sub), _) -> (Changed, beta_reduction ast1sub ovnm res2)
| (Unbox(pvnm, i, ast11, ast12), _) when not (emerge_free pvnm ast2) ->
(Changed, (Unbox(pvnm, i, ast11, (Apply(ast12, ast2), layer)), layer))
| _ -> delta_reduction (Apply(res1, res2), layer)
end
end
end
end (* test *)
else if evlayer > layer then
begin print_for_debug "****APPLY2****" ; (* test *)
print_for_debug ("** " ^ (string_of_abstract_tree ast1)) ; (* test *)
print_for_debug ("** " ^ (string_of_abstract_tree ast2)) ; (* test *)
(Stable, ast)
end (* test *)
else (* if evlayer < layer *)
begin print_for_debug "****APPLY3****" ; (* test *)
print_for_debug ("** " ^ (string_of_abstract_tree ast1)) ; (* test *)
print_for_debug ("** " ^ (string_of_abstract_tree ast2)) ; (* test *)
let (state1, res1) = eval evlayer ast1 in
begin
match state1 with
| Changed -> (Changed, (Apply(res1, ast2), layer))
| Stable ->
let (state2, res2) = eval evlayer ast2 in
(state2, (Apply(res1, res2), layer))
end
end (* test *)
type trial = FirstTrial | AfterFirstTrial
let main (ast : abstract_tree) =
let rec routine (tr : trial) (layer : int) (ast : abstract_tree) =
let (state, res) = eval layer ast in
match (tr, state) with
| (_, Changed) -> routine AfterFirstTrial layer res
| (FirstTrial, Stable) -> res
| (AfterFirstTrial, Stable) -> routine FirstTrial (layer + 1) res
in
routine FirstTrial 0 ast
let trace (ast : abstract_tree) =
let rec routine (tr : trial) (layer : int) (ast : abstract_tree) =
let (state, res) = eval layer ast in
match (tr, state) with
| (_, Changed) -> res :: (routine AfterFirstTrial layer res)
| (FirstTrial, Stable) -> []
| (AfterFirstTrial, Stable) -> routine FirstTrial (layer + 1) res
in
routine FirstTrial 0 ast