jolt/host/chez/regex.ss
Yogthos 5f72ec9bcb Close portable clojure.core gaps: re-groups, letfn, REPL + dynamic vars
Spec coverage dashboard had 6 missing-portable and 24 dynamic-var entries. The
portable ones are now implemented (missing-portable -> 0, dynamic-var -> 14):

- Stateful matcher: re-matcher now returns a real mutable Matcher; re-find over
  it steps through matches and re-groups returns the last match's groups (was an
  inert tagged map). Closes re-groups.
- letfn is interned as a clojure.core var so (resolve 'letfn) matches the JVM. It
  stays a special form (the value is never invoked, not marked a macro).
- *1 *2 *3 *e interned (nil outside a REPL).
- Portable dynamic vars whose default already matches jolt's behaviour:
  *read-eval* *print-dup* *print-namespace-maps* *flush-on-newline*
  *compile-files* *math-context* *command-line-args* *file*.

The remaining 14 dynamic-var entries are host-internal (compile-path,
compiler-options, fn-loader, reader-resolver, repl, source-path, ...) or deferred
pending printer/reader support (*print-length* *print-level*
*default-data-reader-fn*). Corpus rows added for each closed gap; coverage.md
regenerated.
2026-06-26 17:48:21 -04:00

240 lines
12 KiB
Scheme

;; regex on Chez via vendored irregex.
;;
;; Chez has no regex at all. We vendor
;; Alex Shinn's irregex (vendor/irregex, BSD) — a portable Scheme regex with
;; PCRE/Java-style STRING patterns — and wrap jolt's re-* surface over it.
;;
;; irregex maps cleanly onto the Clojure fns: irregex-match is an anchored
;; whole-string match (= re-matches), irregex-search finds the first match
;; anywhere (= re-find), irregex-match-substring extracts group N (0 = whole).
;; Results follow Clojure shape: a 0-group match is the whole string; a grouped
;; match is a jolt VECTOR [whole g1 ...] (a non-participating group is nil); a nil
;; result is jolt-nil; re-seq is a jolt seq (nil when there are no matches).
;;
;; The re-* fns are def-var!'d into clojure.core so prelude / -e code resolves
;; them at runtime (they're NOT subset native-ops: irregex's Unicode/property-
;; class semantics keep them out
;; of the subset-parity corpus). Loaded from rt.ss after def-var! is defined.
;; irregex.scm is portable R[457]RS; two small adaptations for Chez's top level:
;; a cond-expand at expression position (Chez's is library-only), and `error`
;; called with a lone string (Chez's error wants who+msg). The wrapper normalizes
;; both without changing behavior for valid patterns.
(define-syntax cond-expand
(syntax-rules (else)
((_ (else e ...)) (begin e ...))
((_ (else e ...) c ...) (begin e ...))
((_ (req e ...) c ...) (cond-expand c ...))
((_) (if #f #f))))
(define %chez-error error)
(define (error . args)
(if (and (pair? args) (string? (car args)))
(apply %chez-error #f args)
(apply %chez-error args)))
(load "vendor/irregex/irregex.scm")
;; irregex rejects a quantifier applied to anything that already contains one —
;; including a GROUP like (a+)* — because sre-repeater? recurses through submatch.
;; Java only rejects a DANGLING double quantifier (a**); it allows a quantifier on
;; a group whose body is quantified. Restrict the check to a bare leading * / + so
;; a** still errors but (a+)* parses (cuerdas's format tokenizer needs this).
(set! sre-repeater?
(lambda (sre) (and (pair? sre) (memq (car sre) '(* +)) #t)))
;; Unicode property classes \p{...}: irregex's string syntax has no
;; \p{...}, so translate a fixed set of property names
;; to ASCII char classes before compiling. ASCII-only — \p{L} would need
;; UTF-8 high bytes counted as letters, which a Unicode-char Scheme string can't
;; reproduce byte-for-byte; the corpus tests ASCII inputs, where they agree. An
;; unmapped name is left as-is (irregex errors, as before — no new behavior). The
;; ORIGINAL source is kept for printing; only the compiled pattern is translated.
(define (prop-class name)
(cond
;; L/Alpha: ASCII letters + non-ASCII up to just below the UTF-16 surrogate gap
;; (D800). This covers essentially every real letter (Latin/Greek/Cyrillic/CJK/…
;; live below D800); the supplementary planes above it are rare and a range that
;; reaches them makes irregex's char-set construction call integer->char on a
;; surrogate and crash. N/Z stay ASCII-only.
((or (string=? name "L") (string=? name "Alpha")) "a-zA-Z\\x80-\\x{D7FF}")
((string=? name "Lu") "A-Z")
((string=? name "Ll") "a-z")
((or (string=? name "N") (string=? name "Nd") (string=? name "Digit")) "0-9")
((or (string=? name "Z") (string=? name "Zs")) " ")
((string=? name "Ps") "([{")
((string=? name "Pe") ")\\]}")
(else #f)))
;; Tracks whether the cursor is inside a [...] char class: a \p{X} there emits the
;; class CONTENT (inlined), standalone it emits a wrapping [X]. Escapes
;; (\[, \]) don't toggle the class. \P (negation) only wraps when standalone.
(define (translate-prop-classes src)
(let ((len (string-length src)) (out (open-output-string)))
(let loop ((i 0) (in-class #f))
(if (fx>=? i len)
(get-output-string out)
(let ((c (string-ref src i)))
(cond
;; \p{Name} / \P{Name}
((and (char=? c #\\) (fx<? (fx+ i 2) len)
(let ((p (string-ref src (fx+ i 1)))) (or (char=? p #\p) (char=? p #\P)))
(char=? (string-ref src (fx+ i 2)) #\{))
(let* ((close (let scan ((j (fx+ i 3)))
(cond ((fx>=? j len) #f)
((char=? (string-ref src j) #\}) j)
(else (scan (fx+ j 1))))))
(cls (and close (prop-class (substring src (fx+ i 3) close)))))
(cond
((not cls) (write-char c out) (loop (fx+ i 1) in-class))
(in-class (display cls out) (loop (fx+ close 1) in-class))
(else
(display "[" out)
(when (char=? (string-ref src (fx+ i 1)) #\P) (display "^" out))
(display cls out) (display "]" out)
(loop (fx+ close 1) in-class)))))
;; any other escape: copy the pair verbatim, don't toggle class state
((and (char=? c #\\) (fx<? (fx+ i 1) len))
(write-char c out) (write-char (string-ref src (fx+ i 1)) out)
(loop (fx+ i 2) in-class))
((and (not in-class) (char=? c #\[))
(write-char c out) (loop (fx+ i 1) #t))
((and in-class (char=? c #\]))
(write-char c out) (loop (fx+ i 1) #f))
(else (write-char c out) (loop (fx+ i 1) in-class))))))))
;; Inside a [...] class, irregex reads a '-' that follows a shorthand class
;; (\w \d \s \W \D \S) as the start of a range and errors ("bad char-set"); Java
;; reads it as a literal hyphen (a shorthand can't be a range endpoint). Escape
;; such a '-' to \- so the class parses. Only a '-' right after a shorthand and
;; not the class terminator is touched; a '-' after a plain char (a real range
;; like [a-z]) is left alone.
(define (escape-class-shorthand-dash src)
(let ((len (string-length src)) (out (open-output-string)))
(let loop ((i 0) (in-class #f) (after-shorthand #f))
(if (fx>=? i len)
(get-output-string out)
(let ((c (string-ref src i)))
(cond
;; an escape pair: \w-style shorthand sets after-shorthand inside a class
((and (char=? c #\\) (fx<? (fx+ i 1) len))
(let ((n (string-ref src (fx+ i 1))))
(write-char c out) (write-char n out)
(loop (fx+ i 2) in-class
(and in-class (memv n '(#\w #\d #\s #\W #\D #\S)) #t))))
((and (not in-class) (char=? c #\[))
(write-char c out) (loop (fx+ i 1) #t #f))
((and in-class (char=? c #\]))
(write-char c out) (loop (fx+ i 1) #f #f))
;; the case Java reads as a literal hyphen
((and in-class after-shorthand (char=? c #\-)
(fx<? (fx+ i 1) len) (not (char=? (string-ref src (fx+ i 1)) #\])))
(write-char #\\ out) (write-char #\- out)
(loop (fx+ i 1) in-class #f))
(else (write-char c out) (loop (fx+ i 1) in-class #f))))))))
;; Java/Clojure inline flags: a leading (?imsx…) group sets a flag over the whole
;; pattern. irregex has the same semantics but as constructor OPTIONS, not inline
;; syntax (it rejects (?s)/(?s:…)), so peel any leading flag groups off the source
;; and pass the equivalent option symbols. Scoped groups ((?:…), (?=…), (?<n>…))
;; and groups with a flag irregex can't express are left untouched for irregex.
(define (regex-flag->opt c)
(cond ((char=? c #\s) 'single-line) ; DOTALL — . matches newline
((char=? c #\i) 'case-insensitive)
((char=? c #\m) 'multi-line) ; ^/$ match at line boundaries
(else #f)))
(define (regex-parse-flags src)
(let loop ((s src) (opts '()))
(if (and (>= (string-length s) 4)
(char=? (string-ref s 0) #\() (char=? (string-ref s 1) #\?))
(let scan ((i 2) (fs '()))
(cond
((>= i (string-length s)) (values (reverse opts) s))
((char=? (string-ref s i) #\))
(let ((mapped (map regex-flag->opt fs)))
(if (and (pair? fs) (for-all (lambda (x) x) mapped))
(loop (substring s (+ i 1) (string-length s)) (append opts mapped))
(values (reverse opts) s)))) ; unmappable flag — leave as-is
((char=? (string-ref s i) #\:) (values (reverse opts) s)) ; scoped group
(else (scan (+ i 1) (cons (string-ref s i) fs)))))
(values (reverse opts) s))))
;; A jolt regex value: the source string (for printing / str) + the compiled
;; irregex. regex? recognizes it; the printer renders #"source".
(define-record-type regex-t (fields source irx) (nongenerative jolt-regex-v1))
(define (jolt-regex source)
(let-values (((opts pat) (regex-parse-flags source)))
(make-regex-t source
(apply irregex (translate-prop-classes (escape-class-shorthand-dash pat)) opts))))
(define (jolt-regex? x) (regex-t? x))
(define (jolt-re-pattern x) (if (regex-t? x) x (jolt-regex x)))
;; An irregex match -> the Clojure result: whole string (no groups) or the
;; [whole g1 ... gn] vector (nil for a non-participating group).
(define (irx-result m)
(let ((n (irregex-match-num-submatches m)))
(if (= n 0)
(irregex-match-substring m 0)
(let loop ((i n) (acc '()))
(if (< i 0)
(apply jolt-vector acc)
(let ((s (irregex-match-substring m i)))
(loop (- i 1) (cons (if s s jolt-nil) acc))))))))
(define (jolt-re-matches re s)
(let ((m (irregex-match (regex-t-irx (jolt-re-pattern re)) s)))
(if m (irx-result m) jolt-nil)))
;; A stateful matcher (java.util.regex.Matcher): the compiled pattern, the target
;; string, the next search position, and the last successful irregex match. re-find
;; over a matcher steps through non-overlapping matches; re-groups returns the
;; groups of the last one.
(define-record-type matcher-t
(fields irx str (mutable pos) (mutable last))
(nongenerative jolt-matcher-v1))
(define (jolt-re-matcher re s)
(make-matcher-t (regex-t-irx (jolt-re-pattern re)) s 0 #f))
(define (jolt-matcher? x) (matcher-t? x))
;; re-find: stateless over (re s), or stateful over a matcher (advance + remember).
(define jolt-re-find
(case-lambda
((re s)
(let ((m (irregex-search (regex-t-irx (jolt-re-pattern re)) s)))
(if m (irx-result m) jolt-nil)))
((m)
(let* ((str (matcher-t-str m))
(len (string-length str))
(start (matcher-t-pos m))
(mm (and (<= start len) (irregex-search (matcher-t-irx m) str start))))
(if mm
(let ((e (irregex-match-end-index mm 0)))
(matcher-t-last-set! m mm)
(matcher-t-pos-set! m (if (> e start) e (+ start 1)))
(irx-result mm))
(begin (matcher-t-last-set! m #f) jolt-nil))))))
;; re-groups: the groups of the matcher's last successful find. Throws when no
;; match has succeeded, like Clojure's IllegalStateException "No match found".
(define (jolt-re-groups m)
(let ((last (matcher-t-last m)))
(if last (irx-result last)
(jolt-throw (jolt-ex-info "No match found" (jolt-hash-map))))))
;; All non-overlapping matches, left to right. Advance past each match end (or by
;; one on a zero-width match). nil when there are no matches (Clojure: seq-able as
;; nil, so (if-let [m (re-seq ...)] ...) works).
(define (jolt-re-seq re s)
(let ((irx (regex-t-irx (jolt-re-pattern re)))
(len (string-length s)))
(let loop ((start 0) (acc '()))
(let ((m (and (<= start len) (irregex-search irx s start))))
(if m
(let ((e (irregex-match-end-index m 0)))
(loop (if (> e start) e (+ start 1)) (cons (irx-result m) acc)))
(list->cseq (reverse acc)))))))
(def-var! "clojure.core" "re-pattern" jolt-re-pattern)
(def-var! "clojure.core" "re-matches" jolt-re-matches)
(def-var! "clojure.core" "re-find" jolt-re-find)
(def-var! "clojure.core" "re-seq" jolt-re-seq)
(def-var! "clojure.core" "re-matcher" jolt-re-matcher)
(def-var! "clojure.core" "re-groups" jolt-re-groups)
(def-var! "clojure.core" "regex?" jolt-regex?)