version 1.0

1 files changed, 49 insertions, 0 deletions

diff --git a/src/macros.lisp b/src/macros.lisp
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+;; Copyright (C) 2022  colin@cicadas.surf
+
+;; This program is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU Affero General Public License as
+;; published by the Free Software Foundation, either version 3 of the
+;; License, or (at your option) any later version.
+
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU Affero General Public License for more details.
+
+;; You should have received a copy of the GNU Affero General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+;;;; macros.lisp --- utility macros
+
+
+(in-package :lazybones)
+
+(defmacro let-parameters ((&rest names) &body body)
+  "NAMES is a list of symbols. Binds the names to the value of the
+request parameters whose keys compare string-equal to the symbol-name
+of each NAME, or NIL if there is no such parameter."
+  (let ((params (gensym)))
+    `(let ((,params (lazybones:request-parameters)))
+      (let ,(loop for name in names
+                  for string-name = (symbol-name name) 
+                  collect `(,name (cdr (assoc ,string-name ,params :test #'string-equal))))
+        (declare (ignorable ,@names))
+        ,@body))))
+
+(defmacro map-parameters ((&rest params) &body body)
+  "PARAMS is a list of pairs (NAME PARSER).  MAP-PARAMETERS behaves
+exactly like LET-PARAMETERS except that the values boudn to NAMEs are
+first mapped with the PARSER function."
+  (assert (loop for (name parser) in params
+                always (and (symbolp name)
+                            (or (symbolp parser) (functionp parser))))
+          ()
+          "Malformed PARAMS in MAP-PARAMETERS macro")
+
+  (let ((names (mapcar #'car params)))
+    `(let-parameters ,names
+       (let ,(loop for name in names
+                   collect `(,name (when ,name (funcall ',(second (assoc name params)) ,name))))
+         ,@body))))
+