mdw@git.distorted.org.uk Git - sod/blob - combination.lisp

   1 ;;; -*-lisp-*-
   2 ;;;
   3 ;;; Method combinations
   4 ;;;
   5 ;;; (c) 2009 Straylight/Edgeware
   6 ;;;
   7
   8 ;;;----- Licensing notice ---------------------------------------------------
   9 ;;;
  10 ;;; This file is part of the Simple Object Definition system.
  11 ;;;
  12 ;;; SOD is free software; you can redistribute it and/or modify
  13 ;;; it under the terms of the GNU General Public License as published by
  14 ;;; the Free Software Foundation; either version 2 of the License, or
  15 ;;; (at your option) any later version.
  16 ;;;
  17 ;;; SOD is distributed in the hope that it will be useful,
  18 ;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;;; GNU General Public License for more details.
  21 ;;;
  22 ;;; You should have received a copy of the GNU General Public License
  23 ;;; along with SOD; if not, write to the Free Software Foundation,
  24 ;;; Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  25
  26 (cl:in-package #:sod)
  27
  28 ;;;--------------------------------------------------------------------------
  29 ;;; Common behaviour.
  30
  31 (defclass simple-message (basic-message)
  32   ()
  33   (:documentation
  34    "Base class for messages with `simple' method combinations.
  35
  36    A simple method combination is one which has only one method role other
  37    than the `before', `after' and `around' methods provided by BASIC-MESSAGE.
  38    We call these `primary' methods, and the programmer designates them by not
  39    specifying an explicit role.
  40
  41    If the programmer doesn't define any primary methods then the effective
  42    method is null -- i.e., the method entry pointer shows up as a null
  43    pointer."))
  44
  45 (defclass simple-effective-method (basic-effective-method)
  46   ((primary-methods :initarg :primary-methods :initform nil
  47                     :type list :reader effective-method-primary-methods))
  48   (:documentation
  49    "Effective method counterpart to SIMPLE-MESSAGE."))
  50
  51 (defgeneric primary-method-class (message)
  52   (:documentation
  53    "Return the name of the primary direct method class for MESSAGE."))
  54
  55 (defgeneric simple-method-body (method codegen target)
  56   (:documentation
  57    "Generate the body of a simple effective method.
  58
  59    The function is invoked on an effective METHOD, with a CODEGEN to which it
  60    should emit code delivering the method's value to TARGET."))
  61
  62 (defmethod sod-message-method-class
  63     ((message standard-message) (class sod-class) pset)
  64   (if (get-property pset :role :keyword nil)
  65       (call-next-method)
  66       (primary-method-class message)))
  67
  68 (defmethod shared-initialize :after
  69     ((method simple-effective-method) slot-names &key direct-methods)
  70   (declare (ignore slot-names))
  71   (categorize (method direct-methods :bind ((role (sod-method-role method))))
  72       ((primary (null role))
  73        (before (eq role :before))
  74        (after (eq role :after))
  75        (around (eq role :around)))
  76     (with-slots (primary-methods before-methods after-methods around-methods)
  77         method
  78       (setf primary-methods primary
  79             before-methods before
  80             after-methods (reverse after)
  81             around-methods around))))
  82
  83 (defmethod compute-effective-method-entry-functions
  84     ((method standard-effective-method))
  85   (if (effective-method-primary-methods method)
  86       (call-next-method)
  87       nil))
  88
  89 (defmethod compute-effective-method-body
  90     ((method simple-effective-method) codegen target)
  91   (with-slots (message basic-argument-names primary-methods) method
  92     (basic-effective-method-body codegen target method
  93                                  (lambda (target)
  94                                    (simple-method-body method
  95                                                        codegen
  96                                                        target)))))
  97
  98 ;;;--------------------------------------------------------------------------
  99 ;;; Standard method combination.
 100
 101 (defclass standard-message (simple-message)
 102   ()
 103   (:documentation
 104    "Message class for standard method combination.
 105
 106    Standard method combination is a simple method combination where the
 107    primary methods are invoked as a delegation chain, from most- to
 108    least-specific."))
 109
 110 (defclass standard-effective-method (simple-effective-method)
 111   ()
 112   (:documentation
 113    "Effective method counterpart to STANDARD-MESSAGE."))
 114
 115 (defmethod primary-method-class ((message standard-message))
 116   'delegating-direct-method)
 117
 118 (defmethod message-effective-method-class ((message standard-message))
 119   'standard-effective-method)
 120
 121 (defmethod simple-method-body
 122     ((method standard-effective-method) codegen target)
 123   (invoke-delegation-chain codegen
 124                            target
 125                            (effective-method-basic-argument-names method)
 126                            (effective-method-primary-methods method)
 127                            nil))
 128
 129 ;;;----- That's all, folks --------------------------------------------------