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#! /usr/bin/scheme --script

; grep [-v] [file ...]

(define-syntax when
  (syntax-rules ()
    ((when pred? expr ...)
      (if pred? (begin expr ...)))))

(define (complement f) (lambda xs (not (apply f xs))))

(define (read-line . port)
  (define (eat p c)
    (if (and (not (eof-object? (peek-char p)))
             (char=? (peek-char p) c))
        (read-char p)))
  (let ((p (if (null? port) (current-input-port) (car port))))
    (let loop ((c (read-char p)) (line '()))
      (cond ((eof-object? c) (if (null? line) c (list->string (reverse line))))
            ((char=? #\newline c) (eat p #\return) (list->string (reverse line)))
            ((char=? #\return c) (eat p #\newline) (list->string (reverse line)))
            (else (loop (read-char p) (cons c line)))))))

(define-syntax list-match
  (syntax-rules ()
    ((_ expr (pattern fender ... template) ...)
      (let ((obj expr))
        (cond ((list-match-aux obj pattern fender ...
                (list template)) => car) ...
              (else (error 'list-match "pattern failure")))))))

(define-syntax list-match-aux
  (lambda (stx)
    (define (underscore? x)
      (and (identifier? x) (free-identifier=? x (syntax _))))
    (syntax-case stx (quote quasiquote)
      ((_ obj pattern template)
        (syntax (list-match-aux obj pattern #t template)))
      ((_ obj () fender template)
        (syntax (and (null? obj) fender template)))
      ((_ obj underscore fender template)
        (underscore? (syntax underscore))
        (syntax (and fender template)))
      ((_ obj var fender template)
        (identifier? (syntax var))
        (syntax (let ((var obj)) (and fender template))))
      ((_ obj (quote datum) fender template)
        (syntax (and (equal? obj (quote datum)) fender template)))
      ((_ obj (quasiquote datum) fender template)
        (syntax (and (equal? obj (quasiquote datum)) fender template)))
      ((_ obj (kar . kdr) fender template)
        (syntax (and (pair? obj)
                (let ((kar-obj (car obj)) (kdr-obj (cdr obj)))
                  (list-match-aux kar-obj kar
                        (list-match-aux kdr-obj kdr fender template))))))
      ((_ obj const fender template)
        (syntax (and (equal? obj const) fender template))))))

(define (range . args)
  (case (length args)
    ((1) (range 0 (car args) (if (negative? (car args)) -1 1)))
    ((2) (range (car args) (cadr args) (if (< (car args) (cadr args)) 1 -1)))
    ((3) (let ((le? (if (negative? (caddr args)) >= <=)))
           (let loop ((x(car args)) (xs '()))
             (if (le? (cadr args) x)
                 (reverse xs)
                 (loop (+ x (caddr args)) (cons x xs))))))
    (else (error 'range "unrecognized arguments"))))

(define (rx-match? rx text)
  (cond ((null? rx) #t)
        ((equal? (car rx) '(bol))
          (match-here (cdr rx) (string->list text)))
        (else (match rx (string->list text)))))

(define (match rx text)
  (cond ((null? rx) #t)
        ((null? text) (match-here rx text))
        (else (or (match-here rx text) (match rx (cdr text))))))

(define (match-here rx text)
  (if (null? rx) #t
    (case (caar rx)
      ((eol) (null? text))
      ((clo) (match-star rx text))
      (else (and (pair? text)
                 (match-one (car rx) (car text))
                 (match-here (cdr rx) (cdr text)))))))

(define (match-star rx text)
  (cond ((match-here (cdr rx) text) #t)
        ((and (pair? text) (match-one (cdar rx) (car text)))
          (match-star rx (cdr text)))
        (else #f)))

(define (match-one rx text)
  (case (car rx)
    ((any) #t)
    ((lit) (char=? (cadr rx) text))
    ((ccl) (member text (cdr rx)))
    ((ncl) (not (member text (cdr rx))))))

(define (make-rx regexp)
  (let loop ((first? #t) (rs (string->list regexp)) (zs '()))
    (list-match rs
      (() (reverse zs))
      ((#\$) (reverse (cons '(eol) zs)))
      ((#\^ . rest) first? (loop #f rest (cons '(bol) zs)))
      ((#\\ c \#* . rest)
        (loop #f rest (cons (list 'clo 'lit
          (case c ((#\n) #\newline) ((#\t) #\tab) (else c))) zs)))
      ((#\\ c . rest)
        (loop #f rest (cons (list 'lit
          (case c ((#\n) #\newline) ((#\t) #\tab) (else c))) zs)))
      ((#\[ #\^ . rest)
        (list-match (get-class rest)
          ((class) (reverse (cons (cons 'ncl class) zs)))
          ((class rest)
            (if (and (pair? rest) (char=? (car rest) #\*))
                (loop #f (cdr rest) (cons (cons 'clo (cons 'ncl class)) zs))
                (loop #f rest (cons (cons 'ncl class) zs))))))
      ((#\[ . rest)
        (list-match (get-class rest)
          ((class) (reverse (cons (cons 'ccl class) zs)))
          ((class rest)
            (if (and (pair? rest) (char=? (car rest) #\*))
                (loop #f (cdr rest) (cons (cons 'clo (cons 'ccl class)) zs))
                (loop #f rest (cons (cons 'ccl class) zs))))))
      ((#\. #\* . rest) (loop #f rest (cons (list 'clo 'any) zs)))
      ((#\. . rest) (loop #f rest (cons '(any) zs)))
      ((c #\* . rest) (loop #f rest (cons (list 'clo 'lit c) zs)))
      ((c . rest) (loop #f rest (cons (list 'lit c) zs)))
      (else (error 'make-rx "unrecognized regular expression")))))

(define (get-class class)
  (define (char-range a b)
    (map integer->char
      (range (char->integer a) (+ (char->integer b) 1))))
  (let loop ((cs class) (zs '()))
    (list-match cs
      ((#\] . rest) (pair? zs) (list zs rest))
      ((#\] . rest) (loop rest (cons #\] zs)))
      ((#\ c . rest) (loop rest (cons c zs)))
      ((a #\- b . rest)
        (or (and (char-numeric? a) (char-numeric? b) (char<? a b))
            (and (char-upper-case? a) (char-upper-case? b) (char<? a b))
            (and (char-lower-case? a) (char-lower-case? b) (char<? a b)))
        (loop rest (append (char-range a b) zs)))
      ((c . rest) (loop rest (cons c zs)))
      (else (error 'get-class "unrecognized class element")))))

(define (do-input match? filename)
  (do ((line (read-line) (read-line))) ((eof-object? line))
    (when (match? line)
      (when filename (display filename) (display ": "))
      (display line) (newline))))

(define (do-args match? args)
  (cond ((null? args) (do-input match? #f))
        ((null? (cdr args))
          (with-input-from-file (car args)
            (lambda () (do-input match? #f))))
        (else (do ((args args (cdr args))) ((null? args))
                (with-input-from-file (car args)
                  (lambda () (do-input match? (car args))))))))

(define (main args)
  (if (string=? (car args) "-v")
      (do-args
        (complement (lambda (str) (rx-match? (make-rx (cadr args)) str)))
        (cddr args))
      (do-args (lambda (str) (rx-match? (make-rx (car args)) str)) (cdr args))))

(main (cdr (command-line)))

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