3 ;;; Protocol for property sets
5 ;;; (c) 2009 Straylight/Edgeware
8 ;;;----- Licensing notice ---------------------------------------------------
10 ;;; This file is part of the Sensible Object Design, an object system for C.
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.
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.
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.
28 ;;;--------------------------------------------------------------------------
29 ;;; Property representation.
31 (export 'property-key)
32 (defun property-key (name)
33 "Convert NAME into a keyword.
35 If NAME isn't a symbol already, then flip its case (using
36 `frob-identifier'), and intern into the `keyword' package."
39 (string (intern (frob-identifier name) :keyword))))
41 (export '(property propertyp p-name p-value p-type p-key p-seenp))
43 (:predicate propertyp)
45 (:constructor %make-property
47 &key type location seenp
48 &aux (key (property-key name)) (%type type))))
49 "A simple structure for holding a property in a property set.
51 The main useful feature is the ability to tick off properties which have
52 been used, so that we can complain about unrecognized properties.
54 An explicit type tag is necessary because we need to be able to talk
55 distinctly about identifiers, strings and symbols, and we've only got two
56 obvious Lisp types to play with. Sad, but true."
58 (name nil :type (or string symbol) :read-only t)
59 (value nil :type t :read-only t)
60 (%type nil :type symbol :read-only t)
61 (location (file-location nil) :type file-location :read-only t)
62 (key nil :type symbol :read-only t)
63 (seenp nil :type boolean))
64 (define-access-wrapper p-type p-%type :read-only t)
66 (export 'decode-property)
67 (defgeneric decode-property (raw)
68 (:documentation "Decode a RAW value into a TYPE, VALUE pair.")
69 (:method ((raw property)) (values (p-type raw) (p-value raw)))
70 (:method ((raw cons)) (values (car raw) (cdr raw))))
72 (export 'make-property)
73 (defun make-property (name raw-value &key type location seenp)
74 (multiple-value-bind (type value)
76 (values type raw-value)
77 (decode-property raw-value))
78 (%make-property name value
80 :location (file-location location)
83 (export 'coerce-property-value)
84 (defgeneric coerce-property-value (value type wanted)
86 "Convert VALUE, a property of type TYPE, to be of type WANTED.
88 It's sensible to add additional methods to this function, but there are
89 all the ones we need.")
91 ;; If TYPE matches WANTED, we'll assume that VALUE already has the right
92 ;; form. Otherwise, if nothing else matched, then I guess we'll have to
93 ;; say it didn't work.
94 (:method (value type wanted)
95 (if (eql type wanted) value
96 (error "Incorrect type: expected ~A but found ~A" wanted type)))
98 ;; If the caller asks for type T then give him the raw thing.
99 (:method (value type (wanted (eql t)))
100 (declare (ignore type))
103 ;;;--------------------------------------------------------------------------
104 ;;; Property set representation.
106 (export '(pset psetp))
107 (defstruct (pset (:predicate psetp)
108 (:constructor %make-pset)
112 Wrapped up in a structure so that we can define a print function."
113 (hash (make-hash-table) :type hash-table))
115 (export '(make-pset pset-get pset-store pset-map))
116 (declaim (inline make-pset pset-get pset-store pset-map))
119 "Constructor for property sets."
122 (defun pset-get (pset key)
123 "Look KEY up in PSET and return what we find.
125 If there's no property by that name, return nil."
126 (values (gethash key (%pset-hash pset))))
128 (defun pset-store (pset prop)
129 "Store property PROP in PSET.
131 Overwrite or replace any previous property with the same name. Mutates
133 (setf (gethash (p-key prop) (%pset-hash pset)) prop))
135 (defun pset-map (func pset)
136 "Call FUNC for each property in PSET."
137 (maphash (lambda (key value) (declare (ignore key)) (funcall func value))
140 (export 'with-pset-iterator)
141 (defmacro with-pset-iterator ((name pset) &body body)
142 "Evaluate BODY with NAME bound to a macro returning properties from PSET.
144 Evaluating (NAME) returns a property object or nil if all properties have
146 (with-gensyms (next win key value)
147 `(with-hash-table-iterator (,next (%pset-hash ,pset))
149 `(multiple-value-bind (,',win ,',key ,',value) (,',next)
150 (declare (ignore ,',key))
151 (and ,',win ,',value))))
154 ;;;--------------------------------------------------------------------------
155 ;;; `Cooked' property set operations.
157 (export 'store-property)
158 (defun store-property
159 (pset name value &key type location)
160 "Store a property in PSET."
162 (make-property name value :type type :location location)))
164 (export 'get-property)
165 (defun get-property (pset name type &optional default)
166 "Fetch a property from a property set.
168 If a property NAME is not found in PSET, or if a property is found, but
169 its type doesn't match TYPE, then return DEFAULT and nil; otherwise return
170 the value and its file location. In the latter case, mark the property as
173 The value returned depends on the TYPE argument provided. If you pass
174 `nil' then you get back the entire `property' object. If you pass `t',
175 then you get whatever was left in the property set, uninterpreted.
176 Otherwise the value is coerced to the right kind of thing (where possible)
179 The file location at which the property was defined is returned as a
182 If PSET is nil, then return DEFAULT and nil."
184 (let ((prop (and pset (pset-get pset (property-key name)))))
185 (with-default-error-location ((and prop (p-location prop)))
187 (values default nil))
189 (setf (p-seenp prop) t)
190 (values prop (p-location prop)))
192 (setf (p-seenp prop) t)
193 (values (coerce-property-value (p-value prop)
196 (p-location prop)))))))
198 (export 'add-property)
199 (defun add-property (pset name value &key type location)
200 "Add a property to PSET.
202 If a property with the same NAME already exists, report an error."
204 (with-default-error-location (location)
205 (let ((existing (get-property pset name nil)))
207 (error "Property ~S already defined~@[ at ~A~]"
208 name (p-location existing)))
209 (store-property pset name value :type type :location location))))
211 (export 'make-property-set)
212 (defun make-property-set (&rest plist)
213 "Make a new property set, with given properties.
215 This isn't the way to make properties when parsing, but it works well for
216 programmatic generation. The arguments should form a property list
217 (alternating keywords and values is good).
219 An attempt is made to guess property types from the Lisp types of the
220 values. This isn't always successful but it's not too bad. The
221 alternative is manufacturing a `property-value' object by hand and
222 stuffing it into the set."
224 (property-set plist))
226 (export 'property-set)
227 (defgeneric property-set (thing)
229 "Convert THING into a property set.")
230 (:method ((pset pset)) pset)
231 (:method ((list list))
232 "Convert a list into a property set. This works for alists and plists."
233 (multiple-value-bind (next name value)
234 (if (and list (consp (car list)))
235 (values #'cdr #'caar #'cdar)
236 (values #'cddr #'car #'cadr))
237 (do ((pset (make-pset))
238 (list list (funcall next list)))
240 (add-property pset (funcall name list) (funcall value list))))))
242 (export 'check-unused-properties)
243 (defun check-unused-properties (pset)
244 "Issue errors about unused properties in PSET."
246 (pset-map (lambda (prop)
247 (unless (p-seenp prop)
248 (cerror*-with-location (p-location prop)
249 "Unknown property `~A'"
251 (setf (p-seenp prop) t)))
254 ;;;--------------------------------------------------------------------------
257 (export 'default-slot-from-property)
258 (defmacro default-slot-from-property
259 ((instance slot &optional (slot-names t))
261 &optional (pvar (gensym "PROP-"))
264 "Initialize a slot from a property.
266 We initialize SLOT in INSTANCE. In full: if PSET contains a property
267 called NAME, then convert it to TYPE, bind the value to PVAR and evaluate
268 CONVERT-FORMS -- these default to just using the property value. If
269 there's no property, and DEFAULT-FORMS contains at least one non-
270 declaration form, and the slot is named in SLOT-NAMES and currently
271 unbound, then evaluate DEFAULT-FORMS and use their value to compute the
274 (once-only (instance slot slot-names pset property type)
275 (multiple-value-bind (docs decls body)
276 (parse-body default-forms :docp nil)
277 (declare (ignore docs))
279 `(multiple-value-bind (,pvar ,floc)
280 (get-property ,pset ,property ,type)
283 (setf (slot-value ,instance ,slot)
284 (with-default-error-location (,floc)
285 ,@(or convert-forms `(,pvar))))
287 `((default-slot (,instance ,slot ,slot-names)
290 ;;;----- That's all, folks --------------------------------------------------