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js-on-sx: spread ... in array literals and call args

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Parser: jp-array-loop and jp-call-args-loop detect punct "..."
and emit (js-spread inner).

Transpile: when any element is spread, build array/args via
js-array-spread-build with (list "js-value" v) and (list
"js-spread" xs) tags.

Runtime: js-array-spread-build walks items, appending values or
splicing spreads via js-iterable-to-list (handles list/string/dict).

Works in arrays, call args, variadic fns (Math.max(...arr)),
and string spread ([...'abc']).

414/416 unit (+5), 148/148 slice unchanged.
This commit is contained in:
giles
2026-04-23 22:10:15 +00:00
parent b502b8f58e
commit 4800246b23
5 changed files with 137 additions and 24 deletions
Download Patch File Download Diff File Expand all files Collapse all files

26
lib/js/parser.sx
View File

@@ -486,11 +486,18 @@
(cond
((jp-at? st "punct" "]") nil)
(else
(do
(append! elems (jp-parse-assignment st))
(begin
(cond
((jp-at? st "punct" "...")
(begin
(jp-advance! st)
(append!
elems
(list (quote js-spread) (jp-parse-assignment st)))))
(else (append! elems (jp-parse-assignment st))))
(cond
((jp-at? st "punct" ",")
(do (jp-advance! st) (jp-array-loop st elems)))
(begin (jp-advance! st) (jp-array-loop st elems)))
(else nil)))))))
;; ── Entry point ─────────────────────────────────────────────────
@@ -600,11 +607,18 @@
(cond
((jp-at? st "punct" ")") nil)
(else
(do
(append! args (jp-parse-assignment st))
(begin
(cond
((jp-at? st "punct" "...")
(begin
(jp-advance! st)
(append!
args
(list (quote js-spread) (jp-parse-assignment st)))))
(else (append! args (jp-parse-assignment st))))
(cond
((jp-at? st "punct" ",")
(do (jp-advance! st) (jp-call-args-loop st args)))
(begin (jp-advance! st) (jp-call-args-loop st args)))
(else nil)))))))
(define

20
lib/js/runtime.sx
View File

@@ -1750,6 +1750,26 @@
(define Object {:entries js-object-entries :values js-object-values :freeze js-object-freeze :assign js-object-assign :keys js-object-keys})
(define
js-array-spread-build
(fn
(&rest items)
(let
((result (list)))
(for-each
(fn
(item)
(let
((kind (nth item 0)))
(cond
((= kind "js-spread")
(for-each
(fn (x) (append! result x))
(js-iterable-to-list (nth item 1))))
(else (append! result (nth item 1))))))
items)
result)))
(define js-array-is-array (fn (v) (list? v)))
(define js-array-of (fn (&rest args) args))

19
lib/js/test.sh
View File

@@ -1059,6 +1059,18 @@ cat > "$TMPFILE" << 'EPOCHS'
(epoch 2401)
(eval "(js-eval \"'abcd'.slice('1', '3')\")")
;; ── Phase 11.spread: ... in arrays and calls ───────────────────
(epoch 2500)
(eval "(js-eval \"var a=[1,2]; var b=[...a,3,4]; b.length\")")
(epoch 2501)
(eval "(js-eval \"var a=[1,2]; var b=[0,...a,3]; b.join(',')\")")
(epoch 2502)
(eval "(js-eval \"function f(a,b,c){ return a+b+c; } var args=[1,2,3]; f(...args)\")")
(epoch 2503)
(eval "(js-eval \"Math.max(...[1,5,3])\")")
(epoch 2504)
(eval "(js-eval \"var a=[...'abc']; a.length\")")
EPOCHS
@@ -1629,6 +1641,13 @@ check 2307 "Array.from w/ map" '"2,4,6"'
check 2400 "charAt coerces string" '"c"'
check 2401 "slice coerces strings" '"bc"'
# ── Phase 11.spread ───────────────────────────────────────────
check 2500 "spread in array length" '4'
check 2501 "spread middle of array" '"0,1,2,3"'
check 2502 "spread in call args" '6'
check 2503 "spread Math.max" '5'
check 2504 "spread string" '3'
TOTAL=$((PASS + FAIL))
if [ $FAIL -eq 0 ]; then
echo "✓ $PASS/$TOTAL JS-on-SX tests passed"

94
lib/js/transpile.sx
View File

@@ -254,15 +254,15 @@
(fn
(callee args)
(cond
((and (list? callee) (js-tag? callee "js-member"))
((and (js-tag? callee "js-member") (not (js-has-spread? args)))
(let
((recv (js-transpile (nth callee 1))) (key (nth callee 2)))
(list
(js-sym "js-invoke-method")
recv
key
(cons (js-sym "list") (map js-transpile args)))))
((and (list? callee) (js-tag? callee "js-index"))
(js-transpile-args args))))
((and (js-tag? callee "js-index") (not (js-has-spread? args)))
(let
((recv (js-transpile (nth callee 1)))
(key (js-transpile (nth callee 2))))
@@ -270,12 +270,29 @@
(js-sym "js-invoke-method-dyn")
recv
key
(cons (js-sym "list") (map js-transpile args)))))
(js-transpile-args args))))
((js-tag? callee "js-member")
(let
((recv (js-transpile (nth callee 1))) (key (nth callee 2)))
(list
(js-sym "js-invoke-method")
recv
key
(js-transpile-args args))))
((js-tag? callee "js-index")
(let
((recv (js-transpile (nth callee 1)))
(key (js-transpile (nth callee 2))))
(list
(js-sym "js-invoke-method-dyn")
recv
key
(js-transpile-args args))))
(else
(list
(js-sym "js-call-plain")
(js-transpile callee)
(cons (js-sym "list") (map js-transpile args)))))))
(js-transpile-args args))))))
;; ── Array literal ─────────────────────────────────────────────────
@@ -295,10 +312,58 @@
;; order and allows computed values.
(define
js-transpile-array
(fn (elts) (cons (js-sym "list") (map js-transpile elts))))
(fn
(elts)
(if
(js-has-spread? elts)
(cons
(js-sym "js-array-spread-build")
(map
(fn
(e)
(if
(js-tag? e "js-spread")
(list (js-sym "list") "js-spread" (js-transpile (nth e 1)))
(list (js-sym "list") "js-value" (js-transpile e))))
elts))
(cons (js-sym "list") (map js-transpile elts)))))
;; ── Conditional ───────────────────────────────────────────────────
(define
js-has-spread?
(fn
(lst)
(cond
((empty? lst) false)
((js-tag? (first lst) "js-spread") true)
(else (js-has-spread? (rest lst))))))
;; ── Arrow function ────────────────────────────────────────────────
(define
js-transpile-args
(fn
(args)
(if
(js-has-spread? args)
(cons
(js-sym "js-array-spread-build")
(map
(fn
(e)
(if
(js-tag? e "js-spread")
(list (js-sym "list") "js-spread" (js-transpile (nth e 1)))
(list (js-sym "list") "js-value" (js-transpile e))))
args))
(cons (js-sym "list") (map js-transpile args)))))
;; ── Assignment ────────────────────────────────────────────────────
;; `a = b` on an ident → (set! a b).
;; `a += b` on an ident → (set! a (js-add a b)).
;; `obj.k = v` / `obj[k] = v` → (js-set-prop obj "k" v).
(define
js-transpile-object
(fn
@@ -320,8 +385,6 @@
entries)
(list (js-sym "_obj")))))))
;; ── Arrow function ────────────────────────────────────────────────
(define
js-transpile-cond
(fn
@@ -332,11 +395,6 @@
(js-transpile t)
(js-transpile f))))
;; ── Assignment ────────────────────────────────────────────────────
;; `a = b` on an ident → (set! a b).
;; `a += b` on an ident → (set! a (js-add a b)).
;; `obj.k = v` / `obj[k] = v` → (js-set-prop obj "k" v).
(define
js-transpile-arrow
(fn
@@ -367,6 +425,9 @@
(append inits (list (js-transpile body))))))))
(list (js-sym "fn") param-syms body-tr))))
;; ── End-to-end entry points ───────────────────────────────────────
;; Transpile + eval a single JS expression string.
(define
js-transpile-tpl
(fn
@@ -378,6 +439,8 @@
(else
(cons (js-sym "js-template-concat") (js-transpile-tpl-parts parts))))))
;; Transpile a JS expression string to SX source text (for inspection
;; in tests). Useful for asserting the exact emitted tree.
(define
js-transpile-tpl-parts
(fn
@@ -389,9 +452,6 @@
(js-transpile (first parts))
(js-transpile-tpl-parts (rest parts))))))
;; ── End-to-end entry points ───────────────────────────────────────
;; Transpile + eval a single JS expression string.
(define
js-transpile-assign
(fn
@@ -429,8 +489,6 @@
(js-transpile rhs))))
(else (error "js-transpile-assign: unsupported target")))))
;; Transpile a JS expression string to SX source text (for inspection
;; in tests). Useful for asserting the exact emitted tree.
(define
js-compound-update
(fn