ocaml/otherlibs/labltk/browser/searchpos.ml

(*************************************************************************)
(*                                                                       *)
(*                Objective Caml LablTk library                          *)
(*                                                                       *)
(*            Jacques Garrigue, Kyoto University RIMS                    *)
(*                                                                       *)
(*   Copyright 1999 Institut National de Recherche en Informatique et    *)
(*   en Automatique and Kyoto University.  All rights reserved.          *)
(*   This file is distributed under the terms of the GNU Library         *)
(*   General Public License.                                             *)
(*                                                                       *)
(*************************************************************************)

(* $Id$ *)

open Tk
open Jg_tk
open Parsetree
open Types
open Typedtree
open Location
open Longident
open Path
open Env
open Searchid

(* auxiliary functions *)

let (~!) = Jg_memo.fast ~f:Str.regexp

let lines_to_chars n ~text:s =
  let l = String.length s in
  let rec ltc n ~pos =
    if n = 1 or pos >= l then pos else
    if s.[pos] = '\n' then ltc (n-1) ~pos:(pos+1) else ltc n ~pos:(pos+1)
  in ltc n ~pos:0

let in_loc loc ~pos =
  pos >= loc.loc_start & pos < loc.loc_end

let rec string_of_longident = function
    Lident s -> s
  | Ldot (id,s) -> string_of_longident id ^ "." ^ s
  | Lapply (id1, id2) ->
      string_of_longident id1 ^ "(" ^ string_of_longident id2 ^ ")"

let string_of_path p = string_of_longident (Searchid.longident_of_path p)

let parent_path = function
    Pdot (path, _, _) -> Some path
  | Pident _ | Papply _ -> None

let ident_of_path ~default = function
    Pident i -> i
  | Pdot (_, s, _) -> Ident.create s
  | Papply _ -> Ident.create default

let rec head_id = function
    Pident id -> id
  | Pdot (path,_,_) -> head_id path
  | Papply (path,_) -> head_id path (* wrong, but ... *)

let rec list_of_path = function
    Pident id -> [Ident.name id]
  | Pdot (path, s, _) -> list_of_path path @ [s]
  | Papply (path, _) -> list_of_path path (* wrong, but ... *)

(* a simple wrapper *)

class buffer ~size = object
  val buffer = Buffer.create size
  method out ~buf = Buffer.add_substring buffer buf
  method get = Buffer.contents buffer
end

(* Search in a signature *)

type skind = [`Type|`Class|`Module|`Modtype]

exception Found_sig of skind * Longident.t * Env.t

let rec search_pos_type t ~pos ~env =
  if in_loc ~pos t.ptyp_loc then
  begin (match t.ptyp_desc with
    Ptyp_any
  | Ptyp_var _ -> ()
  | Ptyp_variant(tl, _, _) ->
      List.iter tl
        ~f:(fun (_,_,tl) -> List.iter tl ~f:(search_pos_type ~pos ~env))
  | Ptyp_arrow (_, t1, t2) ->
      search_pos_type t1 ~pos ~env;
      search_pos_type t2 ~pos ~env
  | Ptyp_tuple tl ->
      List.iter tl ~f:(search_pos_type ~pos ~env)
  | Ptyp_constr (lid, tl) ->
      List.iter tl ~f:(search_pos_type ~pos ~env);
      raise (Found_sig (`Type, lid, env))
  | Ptyp_object fl ->
      List.iter fl ~f:
        begin function
        | {pfield_desc = Pfield (_, ty)} -> search_pos_type ty ~pos ~env
        | _ -> ()
        end
  | Ptyp_class (lid, tl, _) ->
      List.iter tl ~f:(search_pos_type ~pos ~env);
      raise (Found_sig (`Type, lid, env))
  | Ptyp_alias (t, _) -> search_pos_type ~pos ~env t);
  raise Not_found
  end

let rec search_pos_class_type cl ~pos ~env =
  if in_loc cl.pcty_loc ~pos then begin
    begin match cl.pcty_desc with
      Pcty_constr (lid, _) ->
        raise (Found_sig (`Class, lid, env))
    | Pcty_signature (_, cfl) ->
        List.iter cfl ~f:
          begin function
              Pctf_inher cty -> search_pos_class_type cty ~pos ~env
            | Pctf_val (_, _, Some ty, loc) ->
                if in_loc loc ~pos then search_pos_type ty ~pos ~env
            | Pctf_val _ -> ()
            | Pctf_virt (_, _, ty, loc) ->
                if in_loc loc ~pos then search_pos_type ty ~pos ~env
            | Pctf_meth (_, _, ty, loc) ->
                if in_loc loc ~pos then search_pos_type ty ~pos ~env
            | Pctf_cstr (ty1, ty2, loc) ->
                if in_loc loc ~pos then begin
                  search_pos_type ty1 ~pos ~env;
                  search_pos_type ty2 ~pos ~env
                end
          end
    | Pcty_fun (_, ty, cty) ->
        search_pos_type ty ~pos ~env;
        search_pos_class_type cty ~pos ~env
    end;
    raise Not_found
  end

let search_pos_type_decl td ~pos ~env =
  if in_loc ~pos td.ptype_loc then begin
    begin match td.ptype_manifest with
      Some t -> search_pos_type t ~pos ~env
    | None -> ()
    end;
    begin match td.ptype_kind with
      Ptype_abstract None -> ()
    | Ptype_abstract(Some t) -> search_pos_type t ~pos ~env
    | Ptype_variant dl ->
        List.iter dl
          ~f:(fun (_, tl) -> List.iter tl ~f:(search_pos_type ~pos ~env))
    | Ptype_record dl ->
        List.iter dl ~f:(fun (_, _, t) -> search_pos_type t ~pos ~env)
    end;
    raise Not_found
  end
  
let rec search_pos_signature l ~pos ~env =
  ignore (
  List.fold_left l ~init:env ~f:
  begin fun env pt ->
    let env = match pt.psig_desc with
      Psig_open id ->
        let path, mt = lookup_module id env in
        begin match mt with
          Tmty_signature sign -> open_signature path sign env
        | _ -> env
        end
    | sign_item ->
        try add_signature (Typemod.transl_signature env [pt]) env
        with Typemod.Error _ | Typeclass.Error _
        | Typetexp.Error _  | Typedecl.Error _ -> env
    in
    if in_loc ~pos pt.psig_loc then begin
      begin match pt.psig_desc with
        Psig_value (_, desc) -> search_pos_type desc.pval_type ~pos ~env
      | Psig_type l ->
          List.iter l ~f:(fun (_,desc) -> search_pos_type_decl ~pos desc ~env)
      | Psig_exception (_, l) ->
          List.iter l ~f:(search_pos_type ~pos ~env);
          raise (Found_sig (`Type, Lident "exn", env))
      | Psig_module (_, t) -> 
          search_pos_module t ~pos ~env
      | Psig_modtype (_, Pmodtype_manifest t) ->
          search_pos_module t ~pos ~env
      | Psig_modtype _ -> ()
      | Psig_class l ->
          List.iter l
            ~f:(fun ci -> search_pos_class_type ci.pci_expr ~pos ~env)
      | Psig_class_type l ->
          List.iter l
            ~f:(fun ci -> search_pos_class_type ci.pci_expr ~pos ~env)
      (* The last cases should not happen in generated interfaces *) 
      | Psig_open lid -> raise (Found_sig (`Module, lid, env))
      | Psig_include t -> search_pos_module t ~pos ~env
      end;
      raise Not_found
    end;
    env
  end)

and search_pos_module m ~pos ~env =
  if in_loc m.pmty_loc ~pos then begin
    begin match m.pmty_desc with
      Pmty_ident lid -> raise (Found_sig (`Modtype, lid, env))
    | Pmty_signature sg -> search_pos_signature sg ~pos ~env
    | Pmty_functor (_ , m1, m2) ->
        search_pos_module m1 ~pos ~env;
        search_pos_module m2 ~pos ~env
    | Pmty_with (m, l) ->
        search_pos_module m ~pos ~env;
        List.iter l ~f:
          begin function
              _, Pwith_type t -> search_pos_type_decl t ~pos ~env 
            | _ -> ()
          end
    end;
    raise Not_found
  end

(* the module display machinery *)

type module_widgets =
    { mw_frame: Widget.frame Widget.widget;
      mw_detach: Widget.button Widget.widget;
      mw_edit: Widget.button Widget.widget;
      mw_intf: Widget.button Widget.widget }

let shown_modules = Hashtbl.create 17
let filter_modules () =
  Hashtbl.iter shown_modules ~f:
    begin fun ~key ~data ->
      if not (Winfo.exists data.mw_frame) then
        Hashtbl.remove shown_modules key
    end
let add_shown_module path ~widgets =
  Hashtbl.add shown_modules ~key:path ~data:widgets
and find_shown_module path =
  filter_modules ();
  Hashtbl.find shown_modules path

let is_shown_module path =
  filter_modules ();
  Hashtbl.mem shown_modules path

(* Viewing a signature *)

(* Forward definitions of Viewer.view_defined and Editor.editor *)
let view_defined_ref = ref (fun lid ~env -> ())
let editor_ref = ref (fun ?file ?pos ?opendialog () -> ())

let edit_source ~file ~path ~sign =
  match sign with
    [item] ->
      let id, kind =
        match item with
          Tsig_value (id, _) -> id, Pvalue
        | Tsig_type (id, _) -> id, Ptype
        | Tsig_exception (id, _) -> id, Pconstructor
        | Tsig_module (id, _) -> id, Pmodule
        | Tsig_modtype (id, _) -> id, Pmodtype
        | Tsig_class (id, _) -> id, Pclass
        | Tsig_cltype (id, _) -> id, Pcltype
      in
      let prefix = List.tl (list_of_path path) and name = Ident.name id in
      let pos =
        try
          let chan = open_in file in
          if Filename.check_suffix file ".ml" then
            let parsed = Parse.implementation (Lexing.from_channel chan) in
            close_in chan;
            Searchid.search_structure parsed ~name ~kind ~prefix
          else
            let parsed = Parse.interface (Lexing.from_channel chan) in
            close_in chan;
            Searchid.search_signature parsed ~name ~kind ~prefix
        with _ -> 0
      in !editor_ref ~file ~pos ()
  | _ -> !editor_ref ~file ()

(* List of windows to destroy by Close All *)
let top_widgets = ref []

let rec view_signature ?title ?path ?(env = !start_env) sign =
  let env =
    match path with None -> env
    | Some path -> Env.open_signature path sign env in
  let title =
    match title, path with Some title, _ -> title
    | None, Some path -> string_of_path path
    | None, None -> "Signature"
  in
  let tl, tw, finish =
    try match path with
      None -> raise Not_found
    | Some path ->
        let widgets =
          try find_shown_module path
          with Not_found ->
            view_module path ~env;
            find_shown_module path
        in
        Button.configure widgets.mw_detach
          ~command:(fun () -> view_signature sign ~title ~env);
        pack [widgets.mw_detach] ~side:`Left;
        Pack.forget [widgets.mw_edit; widgets.mw_intf];
        List.iter2 [widgets.mw_edit; widgets.mw_intf] [".ml"; ".mli"] ~f:
          begin fun button ext ->
            try
              let id = head_id path in
              let file =
                Misc.find_in_path !Config.load_path
                  (String.uncapitalize (Ident.name id) ^ ext) in
              Button.configure button
                ~command:(fun () -> edit_source ~file ~path ~sign);
              pack [button] ~side:`Left
            with Not_found -> ()
          end;
        let top = Winfo.toplevel widgets.mw_frame in
        if not (Winfo.ismapped top) then Wm.deiconify top;
        Focus.set top;
        List.iter ~f:destroy (Winfo.children widgets.mw_frame);
        Jg_message.formatted ~title ~on:widgets.mw_frame ~maxheight:15 ()
    with Not_found ->
      let tl, tw, finish = Jg_message.formatted ~title ~maxheight:15 () in
      top_widgets := tl :: !top_widgets;
      tl, tw, finish
  in
  Format.set_max_boxes 100;
  Printtyp.signature Format.std_formatter sign;
  finish ();
  Lexical.init_tags tw;
  Lexical.tag tw;
  Text.configure tw ~state:`Disabled;
  let text = Jg_text.get_all tw in
  let pt =
      try Parse.interface (Lexing.from_string text)
      with Syntaxerr.Error e ->
        let l =
          match e with
            Syntaxerr.Unclosed(l,_,_,_) -> l
          | Syntaxerr.Other l -> l
        in
        Jg_text.tag_and_see  tw ~start:(tpos l.loc_start)
          ~stop:(tpos l.loc_end) ~tag:"error"; []
      | Lexer.Error (_, s, e) ->
         Jg_text.tag_and_see tw ~start:(tpos s) ~stop:(tpos e) ~tag:"error"; []
  in
  Jg_bind.enter_focus tw;
  bind tw ~events:[`Modified([`Control], `KeyPressDetail"s")]
    ~action:(fun _ -> Jg_text.search_string tw);
  bind tw ~events:[`Modified([`Double], `ButtonPressDetail 1)]
    ~fields:[`MouseX;`MouseY] ~breakable:true
    ~action:(fun ev ->
      let `Linechar (l, c) =
        Text.index tw ~index:(`Atxy(ev.ev_MouseX,ev.ev_MouseY), []) in
      try try
        search_pos_signature pt ~pos:(lines_to_chars l ~text + c) ~env;
        break ()
      with Found_sig (kind, lid, env) -> view_decl lid ~kind ~env
      with Not_found | Env.Error _ -> ());
  bind tw ~events:[`ButtonPressDetail 3] ~fields:[`MouseX;`MouseY] ~breakable:true
    ~action:(fun ev ->
      let x = ev.ev_MouseX and y = ev.ev_MouseY in
      let `Linechar (l, c) =
        Text.index tw ~index:(`Atxy(x,y), []) in
      try try
        search_pos_signature pt ~pos:(lines_to_chars l ~text + c) ~env;
        break ()
      with Found_sig (kind, lid, env) ->
        let menu = view_decl_menu lid ~kind ~env ~parent:tw in
        let x = x + Winfo.rootx tw and y = y + Winfo.rooty tw - 10 in
        Menu.popup menu ~x ~y
      with Not_found -> ())

and view_signature_item sign ~path ~env =
  view_signature sign ~title:(string_of_path path)
    ?path:(parent_path path) ~env

and view_module path ~env =
  match find_module path env with
    Tmty_signature sign -> 
      !view_defined_ref (Searchid.longident_of_path path) ~env
  | modtype ->
      let id = ident_of_path path ~default:"M" in
      view_signature_item [Tsig_module (id, modtype)] ~path ~env

and view_module_id id ~env =
  let path, _ = lookup_module id env in
  view_module path ~env

and view_type_decl path ~env =
  let td = find_type path env in
  try match td.type_manifest with None -> raise Not_found
    | Some ty -> match Ctype.repr ty with
        {desc = Tobject _} ->
          let clt = find_cltype path env in
          view_signature_item ~path ~env
            [Tsig_cltype(ident_of_path path ~default:"ct", clt)]
      | _ -> raise Not_found
  with Not_found ->
    view_signature_item ~path ~env
      [Tsig_type(ident_of_path path ~default:"t", td)]

and view_type_id li ~env =
  let path, decl = lookup_type li env in
  view_type_decl path ~env

and view_class_id li ~env =
  let path, cl = lookup_class li env in
  view_signature_item ~path ~env
     [Tsig_class(ident_of_path path ~default:"c", cl)]

and view_cltype_id li ~env =
  let path, clt = lookup_cltype li env in
  view_signature_item ~path ~env
     [Tsig_cltype(ident_of_path path ~default:"ct", clt)]

and view_modtype_id li ~env =
  let path, td = lookup_modtype li env in
  view_signature_item ~path ~env
    [Tsig_modtype(ident_of_path path ~default:"S", td)]

and view_expr_type ?title ?path ?env ?(name="noname") t =
  let title =
    match title, path with Some title, _ -> title
    | None, Some path -> string_of_path path
    | None, None -> "Expression type"
  and path, id =
    match path with None -> None, Ident.create name
    | Some path -> parent_path path, ident_of_path path ~default:name
  in
  view_signature ~title ?path ?env
    [Tsig_value (id, {val_type = t; val_kind = Val_reg})]

and view_decl lid ~kind ~env =
  match kind with
    `Type -> view_type_id lid ~env
  | `Class -> view_class_id lid ~env
  | `Module -> view_module_id lid ~env
  | `Modtype -> view_modtype_id lid ~env

and view_decl_menu lid ~kind ~env ~parent =
  let path, kname =
    try match kind with
      `Type -> fst (lookup_type lid env), "Type"
    | `Class -> fst (lookup_class lid env), "Class"
    | `Module -> fst (lookup_module lid env), "Module"
    | `Modtype -> fst (lookup_modtype lid env), "Module type"
    with Env.Error _ -> raise Not_found
  in
  let menu = Menu.create parent ~tearoff:false in
  let label = kname ^ " " ^ string_of_path path in
  begin match path with
    Pident _ ->
      Menu.add_command menu ~label ~state:`Disabled
  | _ ->
      Menu.add_command menu ~label
        ~command:(fun () -> view_decl lid ~kind ~env);
  end;
  if kind = `Type or kind = `Modtype then begin
    let buf = new buffer ~size:60 in
    let (fo,ff) = Format.get_formatter_output_functions ()
    and margin = Format.get_margin () in
    Format.set_formatter_output_functions ~out:buf#out ~flush:(fun () -> ());
    Format.set_margin 60;
    Format.open_hbox ();
    if kind = `Type then
      Printtyp.type_declaration
        (ident_of_path path ~default:"t")
        Format.std_formatter
        (find_type path env)
    else
      Printtyp.modtype_declaration
        (ident_of_path path ~default:"S")
        Format.std_formatter
        (find_modtype path env);
    Format.close_box (); Format.print_flush ();
    Format.set_formatter_output_functions ~out:fo ~flush:ff;
    Format.set_margin margin;
    let l = Str.split ~sep:~!"\n" buf#get in
    let font =
      let font =
        Option.get Widget.default_toplevel ~name:"font" ~clas:"Font" in
      if font = "" then "7x14" else font
    in
    (* Menu.add_separator menu; *)
    List.iter l
      ~f:(fun label -> Menu.add_command menu ~label ~font ~state:`Disabled)
  end;
  menu

(* search and view in a structure *)

type fkind = [
    `Exp of
      [`Expr|`Pat|`Const|`Val of Path.t|`Var of Path.t|`New of Path.t]
        * Types.type_expr
  | `Class of Path.t * Types.class_type
  | `Module of Path.t * Types.module_type
]
exception Found_str of fkind * Env.t

let view_type kind ~env =
  match kind with
    `Exp (k, ty) ->
      begin match k with
        `Expr -> view_expr_type ty ~title:"Expression type" ~env
      | `Pat -> view_expr_type ty ~title:"Pattern type" ~env
      | `Const -> view_expr_type ty ~title:"Constant type" ~env
      | `Val path ->
          begin try
            let vd = find_value path env in
            view_signature_item ~path ~env
              [Tsig_value(ident_of_path path ~default:"v", vd)]
          with Not_found ->
            view_expr_type ty ~path ~env
          end
      | `Var path ->
          let vd = find_value path env in
          view_expr_type vd.val_type ~env ~path ~title:"Variable type"
      | `New path ->
          let cl = find_class path env in
          view_signature_item ~path ~env
            [Tsig_class(ident_of_path path ~default:"c", cl)]
      end
  | `Class (path, cty) ->
      let cld = { cty_params = []; cty_type = cty;
                  cty_path = path; cty_new = None } in
      view_signature_item ~path ~env
        [Tsig_class(ident_of_path path ~default:"c", cld)]
  | `Module (path, mty) ->
      match mty with
        Tmty_signature sign -> view_signature sign ~path ~env
      | modtype ->
          view_signature_item ~path ~env
            [Tsig_module(ident_of_path path ~default:"M", mty)]

let view_type_menu kind ~env ~parent =
  let title =
    match kind with
      `Exp (`Expr,_) -> "Expression :"
    | `Exp (`Pat, _) -> "Pattern :"
    | `Exp (`Const, _) -> "Constant :"
    | `Exp (`Val path, _) -> "Value " ^ string_of_path path ^ " :"
    | `Exp (`Var path, _) ->
        "Variable " ^ Ident.name (ident_of_path path ~default:"noname") ^ " :"
    | `Exp (`New path, _) -> "Class " ^ string_of_path path ^ " :"
    | `Class (path, _) -> "Class " ^ string_of_path path ^ " :"
    | `Module (path,_) -> "Module " ^ string_of_path path in
  let menu = Menu.create parent ~tearoff:false in
  begin match kind with
    `Exp((`Expr | `Pat | `Const | `Val (Pident _)),_)  ->
      Menu.add_command menu ~label:title ~state:`Disabled
  | `Exp _ | `Class _ | `Module _ ->
      Menu.add_command menu ~label:title
        ~command:(fun () -> view_type kind ~env)
  end;
  begin match kind with `Module _ | `Class _ -> ()
  | `Exp(_, ty) ->
      let buf = new buffer ~size:60 in
      let (fo,ff) = Format.get_formatter_output_functions ()
      and margin = Format.get_margin () in
      Format.set_formatter_output_functions ~out:buf#out ~flush:(fun () -> ());
      Format.set_margin 60;
      Format.open_hbox ();
      Printtyp.reset ();
      Printtyp.mark_loops ty;
      Printtyp.type_expr Format.std_formatter ty;
      Format.close_box (); Format.print_flush ();
      Format.set_formatter_output_functions ~out:fo ~flush:ff;
      Format.set_margin margin;
      let l = Str.split ~sep:~!"\n" buf#get in
      let font =
        let font =
          Option.get Widget.default_toplevel ~name:"font" ~clas:"Font" in
        if font = "" then "7x14" else font
      in
      (* Menu.add_separator menu; *)
      List.iter l ~f:
        begin fun label -> match (Ctype.repr ty).desc with
          Tconstr (path,_,_) ->
            Menu.add_command menu ~label ~font
              ~command:(fun () -> view_type_decl path ~env)
        | Tvariant {row_name = Some (path, _)} ->
            Menu.add_command menu ~label ~font
              ~command:(fun () -> view_type_decl path ~env)
        | _ ->
            Menu.add_command menu ~label ~font ~state:`Disabled
        end
  end;
  menu

let rec search_pos_structure ~pos str =
  List.iter str ~f:
  begin function
    Tstr_eval exp -> search_pos_expr exp ~pos
  | Tstr_value (rec_flag, l) ->
      List.iter l ~f:
      begin fun (pat, exp) ->
        let env =
          if rec_flag = Asttypes.Recursive then exp.exp_env else Env.empty in
        search_pos_pat pat ~pos ~env;
        search_pos_expr exp ~pos
      end
  | Tstr_primitive (_, vd) ->()
  | Tstr_type _ -> ()
  | Tstr_exception _ -> ()
  | Tstr_exn_rebind(_, _) -> ()
  | Tstr_module (_, m) -> search_pos_module_expr m ~pos
  | Tstr_modtype _ -> ()
  | Tstr_open _ -> ()
  | Tstr_class l ->
      List.iter l ~f:(fun (id, _, _, cl) -> search_pos_class_expr cl ~pos)
  | Tstr_cltype _ -> ()
  end

and search_pos_class_expr ~pos cl =
  if in_loc cl.cl_loc ~pos then begin
    begin match cl.cl_desc with
      Tclass_ident path ->
        raise (Found_str (`Class (path, cl.cl_type), !start_env))
    | Tclass_structure cls ->
        List.iter cls.cl_field ~f:
          begin function
              Cf_inher (cl, _, _) ->
                search_pos_class_expr cl ~pos
            | Cf_val (_, _, exp) -> search_pos_expr exp ~pos
            | Cf_meth (_, exp) -> search_pos_expr exp ~pos
            | Cf_let (_, pel, iel) ->
                List.iter pel ~f:
                  begin fun (pat, exp) ->
                    search_pos_pat pat ~pos ~env:exp.exp_env;
                    search_pos_expr exp ~pos
                  end;
                List.iter iel ~f:(fun (_,exp) -> search_pos_expr exp ~pos)
            | Cf_init exp -> search_pos_expr exp ~pos
          end
    | Tclass_fun (pat, iel, cl, _) ->
        search_pos_pat pat ~pos ~env:pat.pat_env;
        List.iter iel ~f:(fun (_,exp) -> search_pos_expr exp ~pos);
        search_pos_class_expr cl ~pos
    | Tclass_apply (cl, el) ->
        search_pos_class_expr cl ~pos;
        List.iter el ~f:(fun (x,_) -> Misc.may (search_pos_expr ~pos) x)
    | Tclass_let (_, pel, iel, cl) ->
        List.iter pel ~f:
          begin fun (pat, exp) ->
            search_pos_pat pat ~pos ~env:exp.exp_env;
            search_pos_expr exp ~pos
          end;
        List.iter iel ~f:(fun (_,exp) -> search_pos_expr exp ~pos);
        search_pos_class_expr cl ~pos
    | Tclass_constraint (cl, _, _, _) ->
        search_pos_class_expr cl ~pos
    end;
    raise (Found_str
             (`Class (Pident (Ident.create "c"), cl.cl_type), !start_env))
  end

and search_pos_expr ~pos exp =
  if in_loc exp.exp_loc ~pos then begin
  begin match exp.exp_desc with
    Texp_ident (path, _) ->
      raise (Found_str (`Exp(`Val path, exp.exp_type), exp.exp_env))
  | Texp_constant v ->
      raise (Found_str (`Exp(`Const, exp.exp_type), exp.exp_env))
  | Texp_let (_, expl, exp) ->
      List.iter expl ~f:
      begin fun (pat, exp') ->
        search_pos_pat pat ~pos ~env:exp.exp_env;
        search_pos_expr exp' ~pos
      end;
      search_pos_expr exp ~pos
  | Texp_function (l, _) ->
      List.iter l ~f:
      begin fun (pat, exp) ->
        search_pos_pat pat ~pos ~env:exp.exp_env;
        search_pos_expr exp ~pos
      end
  | Texp_apply (exp, l) ->
      List.iter l ~f:(fun (x,_) -> Misc.may (search_pos_expr ~pos) x);
      search_pos_expr exp ~pos
  | Texp_match (exp, l, _) ->
      search_pos_expr exp ~pos;
      List.iter l ~f:
      begin fun (pat, exp) ->
        search_pos_pat pat ~pos ~env:exp.exp_env;
        search_pos_expr exp ~pos
      end
  | Texp_try (exp, l) ->
      search_pos_expr exp ~pos;
      List.iter l ~f:
      begin fun (pat, exp) ->
        search_pos_pat pat ~pos ~env:exp.exp_env;
        search_pos_expr exp ~pos
      end
  | Texp_tuple l -> List.iter l ~f:(search_pos_expr ~pos)
  | Texp_construct (_, l) -> List.iter l ~f:(search_pos_expr ~pos)
  | Texp_variant (_, None) -> ()
  | Texp_variant (_, Some exp) -> search_pos_expr exp ~pos
  | Texp_record (l, opt) ->
      List.iter l ~f:(fun (_, exp) -> search_pos_expr exp ~pos);
      (match opt with None -> () | Some exp -> search_pos_expr exp ~pos)
  | Texp_field (exp, _) -> search_pos_expr exp ~pos
  | Texp_setfield (a, _, b) ->
      search_pos_expr a ~pos; search_pos_expr b ~pos
  | Texp_array l -> List.iter l ~f:(search_pos_expr ~pos)
  | Texp_ifthenelse (a, b, c) ->
      search_pos_expr a ~pos; search_pos_expr b ~pos;
      begin match c with None -> ()
      | Some exp -> search_pos_expr exp ~pos
      end
  | Texp_sequence (a,b) ->
      search_pos_expr a ~pos; search_pos_expr b ~pos
  | Texp_while (a,b) ->
      search_pos_expr a ~pos; search_pos_expr b ~pos
  | Texp_for (_, a, b, _, c) ->
      List.iter [a;b;c] ~f:(search_pos_expr ~pos)
  | Texp_when (a, b) ->
      search_pos_expr a ~pos; search_pos_expr b ~pos
  | Texp_send (exp, _) -> search_pos_expr exp ~pos
  | Texp_new (path, _) ->
      raise (Found_str (`Exp(`New path, exp.exp_type), exp.exp_env))
  | Texp_instvar (_,path) ->
      raise (Found_str (`Exp(`Var path, exp.exp_type), exp.exp_env))
  | Texp_setinstvar (_, path, exp) ->
      search_pos_expr exp ~pos;
      raise (Found_str (`Exp(`Var path, exp.exp_type), exp.exp_env))
  | Texp_override (_, l) ->
      List.iter l ~f:(fun (_, exp) -> search_pos_expr exp ~pos)
  | Texp_letmodule (id, modexp, exp) ->
      search_pos_module_expr modexp ~pos;
      search_pos_expr exp ~pos
  end;
  raise (Found_str (`Exp(`Expr, exp.exp_type), exp.exp_env))
  end

and search_pos_pat ~pos ~env pat =
  if in_loc pat.pat_loc ~pos then begin
  begin match pat.pat_desc with
    Tpat_any -> ()
  | Tpat_var id ->
      raise (Found_str (`Exp(`Val (Pident id), pat.pat_type), env))
  | Tpat_alias (pat, _) -> search_pos_pat pat ~pos ~env
  | Tpat_constant _ ->
      raise (Found_str (`Exp(`Const, pat.pat_type), env))
  | Tpat_tuple l ->
      List.iter l ~f:(search_pos_pat ~pos ~env)
  | Tpat_construct (_, l) ->
      List.iter l ~f:(search_pos_pat ~pos ~env)
  | Tpat_variant (_, None, _) -> ()
  | Tpat_variant (_, Some pat, _) -> search_pos_pat pat ~pos ~env
  | Tpat_record l ->
      List.iter l ~f:(fun (_, pat) -> search_pos_pat pat ~pos ~env)
  | Tpat_array l ->
      List.iter l ~f:(search_pos_pat ~pos ~env)
  | Tpat_or (a, b) ->
      search_pos_pat a ~pos ~env; search_pos_pat b ~pos ~env
  end;
  raise (Found_str (`Exp(`Pat, pat.pat_type), env))
  end

and search_pos_module_expr ~pos m =
  if in_loc m.mod_loc ~pos then begin
    begin match m.mod_desc with
      Tmod_ident path ->
        raise
          (Found_str (`Module (path, m.mod_type), m.mod_env))
    | Tmod_structure str -> search_pos_structure str ~pos
    | Tmod_functor (_, _, m) -> search_pos_module_expr m ~pos
    | Tmod_apply (a, b, _) ->
        search_pos_module_expr a ~pos; search_pos_module_expr b ~pos
    | Tmod_constraint (m, _, _) -> search_pos_module_expr m ~pos
    end;
    raise (Found_str (`Module (Pident (Ident.create "M"), m.mod_type),
                      m.mod_env))
  end