69 lines
2.2 KiB
Common Lisp
69 lines
2.2 KiB
Common Lisp
;;; Copyright 2013 Google Inc.
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;;;
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;;; Licensed under the Apache License, Version 2.0 (the "License");
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;;; you may not use this file except in compliance with the License.
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;;; You may obtain a copy of the License at
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;;;
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;;; http://www.apache.org/licenses/LICENSE-2.0
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;;;
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;;; Unless required by applicable law or agreed to in writing, software
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;;; distributed under the License is distributed on an "AS IS" BASIS,
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;;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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;;; See the License for the specific language governing permissions and
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;;; limitations under the License.
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(define-test if
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;; IF only evaluates and returns one branch of a conditional expression.
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(assert-equal :true (if t :true :false))
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(assert-equal :false (if nil :true :false))
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;; This also applies to side effects that migh or might not be evaluated.
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(let ((result))
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(if t
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(setf result :true)
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(setf result :false))
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(assert-equal :true result)
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(if nil
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(setf result :true)
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(setf result :false))
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(assert-equal :false result)))
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(define-test when-unless
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;; WHEN and UNLESS are like one-branched IF statements.
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(let ((when-result nil)
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(when-numbers '())
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(unless-result nil)
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(unless-numbers '()))
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(dolist (x '(1 2 3 4 5 6 7 8 9 10))
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(when (> x 5)
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(setf when-result x)
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(push x when-numbers))
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(unless (> x 5)
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(setf unless-result x)
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(push x unless-numbers)))
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(assert-equal 10 when-result)
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(assert-equal '(10 9 8 7 6) when-numbers)
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(assert-equal 5 unless-result)
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(assert-equal '(5 4 3 2 1) unless-numbers)))
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(define-test and-short-circuit
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;; AND only evaluates forms until one evaluates to NIL.
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(assert-equal 5
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(let ((x 0))
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(and
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(setf x (+ 2 x))
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(setf x (+ 3 x))
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nil
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(setf x (+ 4 x)))
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x)))
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(define-test or-short-circuit
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;; OR only evaluates forms until one evaluates to non-NIL.
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(assert-equal 2
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(let ((x 0))
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(or
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(setf x (+ 2 x))
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(setf x (+ 3 x))
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nil
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(setf x (+ 4 x)))
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x)))
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