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Code Issues 1 Releases Wiki Activity

Use gensym in do-compare macro.

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Improve hygiene of macro in case later changes introduce subtle bugs.
This commit is contained in:
Calvin Rose 2024-07-31 11:19:44 -05:00
parent aaeaa3a944
commit 631622aa48
1 changed files with 13 additions and 9 deletions
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22
src/boot/boot.janet
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@ -832,17 +832,21 @@
(defmacro- do-compare
[x y]
(def f (gensym))
(def f-res (gensym))
(def g (gensym))
(def g-res (gensym))
~(do
(def f (get ,x :compare))
(def f-res (if f (f ,x ,y)))
(if f-res
f-res
(def ,f (,get ,x :compare))
(def ,f-res (if ,f (,f ,x ,y)))
(if ,f-res
,f-res
(do
(def g (get ,y :compare))
(def g-res (if g (- (g ,y ,x))))
(if g-res
g-res
(cmp ,x ,y))))))
(def ,g (,get ,y :compare))
(def ,g-res (if ,g (,- (,g ,y ,x))))
(if ,g-res
,g-res
(,cmp ,x ,y))))))
(defn compare
``Polymorphic compare. Returns -1, 0, 1 for x < y, x = y, x > y respectively.