jolt/host/chez/bigdec.ss
Yogthos e434356590 Replace str-render/instance-check set! chains with registries
jolt-str-render-one and instance-check were each extended by a chain of
set!-wrapping closures spread across ~10 and ~5 host files, so the real
behavior of either was scattered and load-order-dependent. Give each a
registry the base file owns: converters.ss/records-interop.ss define the
registry plus a register-* helper, and each extending file registers one arm
instead of capturing %prev and set!-ing the global.

str-render arms are type-disjoint; instance-check arms run newest-first (the
old outermost-wins order) and may return 'pass to defer. The string-token ->
symbol normalization the natives-array arm did for every inner arm moves to
the dispatcher head; array tokens stay strings for that arm to decide.

jolt-ogib.14. Runtime-only shims, no re-mint.
2026-06-23 09:05:36 -04:00

82 lines
3.7 KiB
Scheme

;; BigDecimal. A jbigdec is {unscaled, scale} over Chez arbitrary-precision exact
;; integers; its value is unscaled * 10^-scale (1.5M = {15,1}, 1.00M = {100,2},
;; 3M = {3,0}). M-suffix literals read to a :bigdec form that the back end lowers
;; to jolt-bigdec-from-string; bigdec coerces a number/string. Equality is by
;; value (1.0M = 1.00M), str drops the M, pr keeps it, class is
;; java.math.BigDecimal. Arithmetic contagion is not modelled.
(define-record-type jbigdec (fields unscaled scale) (nongenerative chez-jbigdec-v1))
(define (bd-index-char s ch)
(let loop ((i 0))
(cond ((>= i (string-length s)) #f)
((char=? (string-ref s i) ch) i)
(else (loop (+ i 1))))))
;; "1.50" -> {150,2}; "3" -> {3,0}; "-0.0" -> {0,1}; ".5" -> {5,1}.
(define (jolt-bigdec-from-string s)
(let* ((neg (and (> (string-length s) 0) (char=? (string-ref s 0) #\-)))
(sgn (and (> (string-length s) 0) (or neg (char=? (string-ref s 0) #\+))))
(s1 (if sgn (substring s 1 (string-length s)) s))
(sign (if neg -1 1))
(dot (bd-index-char s1 #\.)))
(if dot
(let* ((intp (substring s1 0 dot))
(fracp (substring s1 (+ dot 1) (string-length s1)))
(digs (string-append intp fracp))
(unscaled (if (= 0 (string-length digs)) 0 (string->number digs))))
(make-jbigdec (* sign unscaled) (string-length fracp)))
(make-jbigdec (* sign (string->number s1)) 0))))
;; bigdec coercion: a bigdec is itself; an exact integer keeps scale 0; a string
;; or any other number routes through its decimal text.
(define (jolt-bigdec x)
(cond
((jbigdec? x) x)
((and (number? x) (exact? x) (integer? x)) (make-jbigdec x 0))
((string? x) (jolt-bigdec-from-string x))
((number? x) (jolt-bigdec-from-string (jolt-num->string x)))
(else (error #f "bigdec: cannot coerce" x))))
;; value equality: unscaled_a * 10^scale_b == unscaled_b * 10^scale_a.
(define (jbigdec=? a b)
(= (* (jbigdec-unscaled a) (expt 10 (jbigdec-scale b)))
(* (jbigdec-unscaled b) (expt 10 (jbigdec-scale a)))))
;; render the decimal text (no M): insert the point `scale` digits from the right.
(define (jbigdec->string bd)
(let* ((u (jbigdec-unscaled bd)) (sc (jbigdec-scale bd))
(neg (< u 0)) (digs (number->string (abs u))))
(string-append
(if neg "-" "")
(if (<= sc 0)
digs
(let* ((padded (if (<= (string-length digs) sc)
(string-append (make-string (- (+ sc 1) (string-length digs)) #\0) digs)
digs))
(pl (string-length padded)))
(string-append (substring padded 0 (- pl sc)) "." (substring padded (- pl sc) pl)))))))
;; --- wire into the value model ----------------------------------------------
(def-var! "clojure.core" "bigdec" jolt-bigdec)
;; equality: a bigdec equals only another bigdec, by value (matching (= 3M 3) = false).
(define %bd-jolt=2 jolt=2)
(set! jolt=2 (lambda (a b)
(cond ((and (jbigdec? a) (jbigdec? b)) (jbigdec=? a b))
((or (jbigdec? a) (jbigdec? b)) #f)
(else (%bd-jolt=2 a b)))))
;; str drops the M; pr/pr-str keep it.
(register-str-render! jbigdec? jbigdec->string)
(define %bd-pr-str jolt-pr-str)
(set! jolt-pr-str (lambda (x) (if (jbigdec? x) (string-append (jbigdec->string x) "M") (%bd-pr-str x))))
(define %bd-pr-readable jolt-pr-readable)
(set! jolt-pr-readable (lambda (x) (if (jbigdec? x) (string-append (jbigdec->string x) "M") (%bd-pr-readable x))))
;; class / decimal?
(define %bd-class jolt-class)
(set! jolt-class (lambda (x) (if (jbigdec? x) "java.math.BigDecimal" (%bd-class x))))
(def-var! "clojure.core" "class" jolt-class)
(set! jolt-decimal? (lambda (x) (jbigdec? x)))
(def-var! "clojure.core" "decimal?" jolt-decimal?)