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Comment:s_expression-interpreters: new package providing a S-expression interpreter which dispatch to client-provided commands
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: 6e4b5836c5d2de67cef1ae8054c0f03da04633e0
User & Date: nat on 2014-03-12 21:26:44
Other Links: manifest | tags
Context
2014-03-13
21:12
Add missing Preelaborate pragmas check-in: d53403fc11 user: nat tags: trunk
2014-03-12
21:26
s_expression-interpreters: new package providing a S-expression interpreter which dispatch to client-provided commands check-in: 6e4b5836c5 user: nat tags: trunk
2014-03-11
19:33
coverage.sh: add more configuration variables for better flexibility check-in: 577fa9c3d6 user: nat tags: trunk
Changes

Added src/natools-s_expressions-interpreters.adb version [db1846c47e].








































































































































































































































































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------------------------------------------------------------------------------
-- Copyright (c) 2013-2014, Natacha Porté                                   --
--                                                                          --
-- Permission to use, copy, modify, and distribute this software for any    --
-- purpose with or without fee is hereby granted, provided that the above   --
-- copyright notice and this permission notice appear in all copies.        --
--                                                                          --
-- THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES --
-- WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF         --
-- MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR  --
-- ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES   --
-- WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN    --
-- ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF  --
-- OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.           --
------------------------------------------------------------------------------

package body Natools.S_Expressions.Interpreters is

   ---------------------
   -- Atom Comparison --
   ---------------------

   function Less_Than (Left, Right : Atom) return Boolean is
   begin
      return Left'Length < Right'Length
        or else (Left'Length = Right'Length and then Left < Right);
   end Less_Than;



   -----------------
   -- Interpreter --
   -----------------

   procedure Add_Command
     (Self : in out Interpreter;
      Name : in Atom;
      Cmd : in Command'Class) is
   begin
      Self.Commands.Insert (Name, Cmd);
      Self.Max_Length := Count'Max (Self.Max_Length, Name'Length);
   end Add_Command;


   procedure Set_Fallback
     (Self : in out Interpreter;
      Name : in Atom)
   is
      function Create return Atom;

      function Create return Atom is
      begin
         return Name;
      end Create;
   begin
      Self.Fallback_Name.Replace (Create'Access);
   end Set_Fallback;


   procedure Reset_Fallback (Self : in out Interpreter) is
   begin
      Self.Fallback_Name.Reset;
   end Reset_Fallback;


   not overriding procedure Execute
     (Self : in out Interpreter;
      Expression : in out Lockable.Descriptor'Class;
      State : in out Shared_State;
      Context : in Shared_Context)
   is
      Event : Events.Event := Expression.Current_Event;
      Lock_State : Lockable.Lock_State;
   begin
      loop
         case Event is
            when Events.Add_Atom =>
               Self.Execute (State, Context, Expression.Current_Atom);
            when Events.Open_List =>
               Expression.Lock (Lock_State);
               begin
                  Expression.Next (Event);
                  if Event = Events.Add_Atom then
                     Self.Execute (State, Context, Expression);
                  end if;
               exception
                  when others =>
                     Expression.Unlock (Lock_State, False);
                     raise;
               end;
               Expression.Unlock (Lock_State);
            when Events.Close_List | Events.End_Of_Input | Events.Error =>
               exit;
         end case;

         Expression.Next (Event);
      end loop;
   end Execute;


   not overriding procedure Execute
     (Self : in out Interpreter;
      Fallback : in out Command'Class;
      Expression : in out Lockable.Descriptor'Class;
      State : in out Shared_State;
      Context : in Shared_Context)
   is
      procedure Dispatch (Process : not null access procedure
                            (Name : in Atom; Cmd : in out Command'Class));
      procedure Process_Atom (Name : in Atom; Cmd : in out Command'Class);
      procedure Process_Exp (Name : in Atom; Cmd : in out Command'Class);

      procedure Dispatch (Process : not null access procedure
                            (Name : in Atom; Cmd : in out Command'Class))
      is
         procedure Process_Fallback (Name : in Atom);

         procedure Process_Fallback (Name : in Atom) is
         begin
            Process (Name, Fallback);
         end Process_Fallback;

         Buffer : Atom (1 .. Self.Max_Length);
         Length : Count;
         Cursor : Command_Maps.Cursor;
      begin
         Expression.Read_Atom (Buffer, Length);
         if Length > Self.Max_Length then
            Expression.Query_Atom (Process_Fallback'Access);
         else
            Cursor := Self.Commands.Find (Buffer (1 .. Length));
            if Command_Maps.Has_Element (Cursor) then
               Self.Commands.Update_Element (Cursor, Process);
            else
               Process (Buffer (1 .. Length), Fallback);
            end if;
         end if;
      end Dispatch;

      procedure Process_Atom (Name : in Atom; Cmd : in out Command'Class) is
      begin
         Cmd.Execute (State, Context, Name);
      end Process_Atom;

      procedure Process_Exp (Name : in Atom; Cmd : in out Command'Class) is
         pragma Unreferenced (Name);
      begin
         Cmd.Execute (State, Context, Expression);
      end Process_Exp;

      Event : Events.Event := Expression.Current_Event;
      Lock_State : Lockable.Lock_State;
   begin
      loop
         case Event is
            when Events.Add_Atom =>
               Dispatch (Process_Atom'Access);

            when Events.Open_List =>
               Expression.Lock (Lock_State);
               begin
                  Expression.Next (Event);
                  if Event = Events.Add_Atom then
                     Dispatch (Process_Exp'Access);
                  end if;
               exception
                  when others =>
                     Expression.Unlock (Lock_State, False);
                     raise;
               end;
               Expression.Unlock (Lock_State);

            when Events.Close_List | Events.End_Of_Input | Events.Error =>
               exit;
         end case;

         Expression.Next (Event);
      end loop;
   end Execute;


   overriding procedure Execute
     (Self : in out Interpreter;
      State : in out Shared_State;
      Context : in Shared_Context;
      Name : in Atom)
   is
      procedure Process_Atom (Key : in Atom; Cmd : in out Command'Class);

      procedure Process_Atom (Key : in Atom; Cmd : in out Command'Class) is
         pragma Unreferenced (Key);
      begin
         Cmd.Execute (State, Context, Name);
      end Process_Atom;

      Cursor : Command_Maps.Cursor;
   begin
      if Name'Length <= Self.Max_Length then
         Cursor := Self.Commands.Find (Name);
         if Command_Maps.Has_Element (Cursor) then
            Self.Commands.Update_Element (Cursor, Process_Atom'Access);
            return;
         end if;
      end if;

      if not Self.Fallback_Name.Is_Empty then
         Cursor := Self.Commands.Find (Self.Fallback_Name.Query.Data.all);
         if Command_Maps.Has_Element (Cursor) then
            Self.Commands.Update_Element (Cursor, Process_Atom'Access);
            return;
         end if;
      end if;

      raise Command_Not_Found
        with "Unknown command """ & To_String (Name) & '"';
   end Execute;


   overriding procedure Execute
     (Self : in out Interpreter;
      State : in out Shared_State;
      Context : in Shared_Context;
      Cmd : in out Lockable.Descriptor'Class)
   is
      procedure Process_Exp (Name : in Atom; Actual : in out Command'Class);

      procedure Process_Exp (Name : in Atom; Actual : in out Command'Class) is
         pragma Unreferenced (Name);
      begin
         Actual.Execute (State, Context, Cmd);
      end Process_Exp;

      Buffer : Atom (1 .. Self.Max_Length);
      Length : Count;
      Cursor : Command_Maps.Cursor;
   begin
      if Cmd.Current_Event /= Events.Add_Atom then
         return;
      end if;

      Cmd.Read_Atom (Buffer, Length);

      if Length <= Self.Max_Length then
         Cursor := Self.Commands.Find (Buffer (1 .. Length));
         if Command_Maps.Has_Element (Cursor) then
            Self.Commands.Update_Element (Cursor, Process_Exp'Access);
            return;
         end if;
      end if;

      if not Self.Fallback_Name.Is_Empty then
         Cursor := Self.Commands.Find (Self.Fallback_Name.Query.Data.all);
         if Command_Maps.Has_Element (Cursor) then
            Self.Commands.Update_Element (Cursor, Process_Exp'Access);
            return;
         end if;
      end if;

      raise Command_Not_Found
        with "Unknown command """ & To_String (Cmd.Current_Atom) & '"';
   end Execute;

end Natools.S_Expressions.Interpreters;

Added src/natools-s_expressions-interpreters.ads version [36f18e7166].

























































































































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------------------------------------------------------------------------------
-- Copyright (c) 2013-2014, Natacha Porté                                   --
--                                                                          --
-- Permission to use, copy, modify, and distribute this software for any    --
-- purpose with or without fee is hereby granted, provided that the above   --
-- copyright notice and this permission notice appear in all copies.        --
--                                                                          --
-- THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES --
-- WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF         --
-- MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR  --
-- ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES   --
-- WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN    --
-- ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF  --
-- OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.           --
------------------------------------------------------------------------------

------------------------------------------------------------------------------
-- Natools.S_Expressions.Interpreters provides an implemntation of a        --
-- dispatching command interpreter. The base list of a given S-expression   --
-- is considered as list of command, either argumentless (atoms) or with a  --
-- S-expression argument (sublist). Sublists that don't start with an atom  --
-- are silently ignored and can be used as comments.                        --
--                                                                          --
-- Formal types represent common objets for all the command, Shared_State   --
-- begin read/write while Shared_Context is read-only.                      --
------------------------------------------------------------------------------

with Natools.S_Expressions.Lockable;

private with Ada.Containers.Indefinite_Ordered_Maps;
private with Natools.S_Expressions.Atom_Buffers;

generic
   type Shared_State (<>) is limited private;
   type Shared_Context (<>) is limited private;

package Natools.S_Expressions.Interpreters is
   pragma Preelaborate (Interpreters);

   Command_Not_Found : exception;


   type Command is interface;

   procedure Execute
     (Self : in out Command;
      State : in out Shared_State;
      Context : in Shared_Context;
      Name : in Atom)
     is null;
      --  Execute a single argumentless command

   procedure Execute
     (Self : in out Command;
      State : in out Shared_State;
      Context : in Shared_Context;
      Cmd : in out Lockable.Descriptor'Class)
     is null;
      --  Execute a single command with arguments


   type Interpreter is new Command with private;

   procedure Add_Command
     (Self : in out Interpreter;
      Name : in Atom;
      Cmd : in Command'Class);

   procedure Set_Fallback
     (Self : in out Interpreter;
      Name : in Atom);

   procedure Reset_Fallback (Self : in out Interpreter);

   not overriding procedure Execute
     (Self : in out Interpreter;
      Expression : in out Lockable.Descriptor'Class;
      State : in out Shared_State;
      Context : in Shared_Context);
      --  Execute an expression, raising Command_Not_Found on unknown commands

   not overriding procedure Execute
     (Self : in out Interpreter;
      Fallback : in out Command'Class;
      Expression : in out Lockable.Descriptor'Class;
      State : in out Shared_State;
      Context : in Shared_Context);
      --  Execute an expression with temporary fallback for unknown commands

   overriding procedure Execute
     (Self : in out Interpreter;
      State : in out Shared_State;
      Context : in Shared_Context;
      Name : in Atom);
      --  Execute a single argumentless command

   overriding procedure Execute
     (Self : in out Interpreter;
      State : in out Shared_State;
      Context : in Shared_Context;
      Cmd : in out Lockable.Descriptor'Class);
      --  Execute a single command with arguments


private

   type Exception_Command is new Command with null record;

   function Less_Than (Left, Right : Atom) return Boolean;

   package Command_Maps is new Ada.Containers.Indefinite_Ordered_Maps
     (Atom, Command'Class, Less_Than);

   type Interpreter is new Command with record
      Commands : Command_Maps.Map;
      Max_Length : Count := 0;
      Fallback_Name : Atom_Buffers.Atom_Refs.Reference;
   end record;

end Natools.S_Expressions.Interpreters;