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add support for & _ to match macro

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This commit adds support for using & _ syntax to bind the remaining
values in an array in the match macro.

The commit also adds a few tests for the new syntax in suite0008
This commit is contained in:
Ian Shehadeh
2022-01-19 13:29:34 -05:00
parent 0d31674166
commit db631097b1
2 changed files with 28 additions and 6 deletions
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src/boot/boot.janet
+24 -6
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@@ -1751,10 +1751,18 @@
(break)
# match data structure template
(or isarr (= t :struct) (= t :table))
(or (= t :struct) (= t :table))
(eachp [i sub-pattern] pattern
(visit-pattern-1 b2g s i sub-pattern))
isarr
(do
(when isarr (get-length-sym s))
(get-length-sym s)
(eachp [i sub-pattern] pattern
(when (= sub-pattern '&)
# TODO: check that & is followed by something
(put b2g (pattern (inc i)) @[[slice s i]])
(break))
(visit-pattern-1 b2g s i sub-pattern)))
# match global unification
@@ -1774,14 +1782,24 @@
(def isarr (or (= t :array) (and (= t :tuple) (= (tuple/type pattern) :brackets))))
(when isarr
(array/push anda (get-length-sym s))
(array/push anda [<= (length pattern) (get-length-sym s)]))
(def pattern-len
(if-let [ rest-idx (find-index (fn [x] (= x '&)) pattern) ]
rest-idx
(length pattern)))
(array/push anda [<= pattern-len (get-length-sym s)]))
(cond
# match data structure template
(or isarr (= t :struct) (= t :table))
(or (= t :struct) (= t :table))
(eachp [i sub-pattern] pattern
(when (not isarr)
(array/push anda [not= nil (get-sym s i)]))
(array/push anda [not= nil (get-sym s i)])
(visit-pattern-2 anda gun preds s i sub-pattern))
isarr
(eachp [i sub-pattern] pattern
# stop recursing to sub-patterns if the rest sigil is found
(when (= sub-pattern '&)
(break))
(visit-pattern-2 anda gun preds s i sub-pattern))
# match local binding