(maint) add assoc-if-new
assoc-if-new behaves as assoc does only if the key does not exist in the
map already. If the key already exists in the map, it's a noop.
Wyatt Alt
7 years ago
| 1030 | 1030 |
[]
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| 1031 | 1031 |
(with-open [s (java.net.ServerSocket. 0)]
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| 1032 | 1032 |
(.getLocalPort s)))
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1033 |
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1034 |
(defmacro assoc-if-new
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1035 |
"Assocs the provided values with the corresponding keys if and only
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|
1036 |
if the key is not already present in map."
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1037 |
[map key val & kvs]
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1038 |
{:pre [(even? (count kvs))]}
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1039 |
(let [deferred-kvs (vec (for [[k v] (cons [key val] (partition 2 kvs))]
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1040 |
[k `(fn [] ~v)]))]
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1041 |
`(let [updates# (for [[k# v#] ~deferred-kvs
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1042 |
:when (= ::not-found (get ~map k# ::not-found))]
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1043 |
[k# (v#)])]
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1044 |
(merge ~map (into {} updates#)))))
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| 737 | 737 |
(let [open-ports (set (take 60000 (repeatedly open-port-num)))]
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| 738 | 738 |
(is (every? pos? open-ports))
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| 739 | 739 |
(is (not (contains? open-ports port-in-use)))))))
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740 |
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741 |
(deftest assoc-if-new-test
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742 |
(testing "assoc-if-new assocs appropriately"
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743 |
(is (= {:a "foo"}
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744 |
(assoc-if-new {:a "foo"} :a "bar")))
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745 |
(is (= {:a "bar" :b "foo"}
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746 |
(assoc-if-new {:b "foo"} :a "bar")))
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747 |
(is (= {:a "foo" :b "bar"}
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|
748 |
(assoc-if-new {} :a "foo" :b "bar")))
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749 |
(is (= {:a "foo" :b nil}
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750 |
(assoc-if-new {:b nil} :a "foo" :b "bar")))
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751 |
(is (= {:a "foo" :b "baz"}
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752 |
(assoc-if-new {:b "baz"} :a "foo" :b "bar")))))
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