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+;;; "report.scm" relational-database-utility
+; Copyright 1995 Aubrey Jaffer
+;
+;Permission to copy this software, to redistribute it, and to use it
+;for any purpose is granted, subject to the following restrictions and
+;understandings.
+;
+;1.  Any copy made of this software must include this copyright notice
+;in full.
+;
+;2.  I have made no warrantee or representation that the operation of
+;this software will be error-free, and I am under no obligation to
+;provide any services, by way of maintenance, update, or otherwise.
+;
+;3.  In conjunction with products arising from the use of this
+;material, there shall be no use of my name in any advertising,
+;promotional, or sales literature without prior written consent in
+;each case.
+
+;;;; Considerations for report generation:
+; * columnar vs. fixed-multi-line vs. variable-multi-line
+; * overflow lines within column boundaries.
+; * break overflow across page?
+; * Page headers and footers (need to know current/previous record-number
+;   and next record-number).
+; * Force page break on general expression (needs next row as arg).
+; * Hierachical reports.
+
+;================================================================
+
+(require 'format)
+(require 'database-utilities)
+
+(define (dbutil:database arg)
+  (cond ((procedure? arg) arg)
+	((string? arg) (dbutil:open-database arg))
+	((symbol? arg) (slib:eval arg))
+	(else (slib:error "can't coerce to database: " arg))))
+
+(define (dbutil:table arg)
+  (cond ((procedure? arg) arg)
+	((and (list? arg) (= 2 (length arg)))
+	 (((dbutil:database (car arg)) 'open-table) (cadr arg) #f))))
+
+(define (dbutil:print-report table header reporter footer . args)
+  (define output-port (and (pair? args) (car args)))
+  (define page-height (and (pair? args) (pair? (cdr args)) (cadr args)))
+  (define minimum-break
+    (and (pair? args) (pair? (cdr args)) (pair? (cddr args)) (caddr args)))
+  (set! table (dbutil:table table))
+  ((lambda (fun)
+     (cond ((output-port? output-port)
+	    (fun output-port))
+	   ((string? output-port)
+	    (call-with-output-file output-port fun))
+	   ((or (boolean? output-port) (null? output-port))
+	    (fun (current-output-port)))
+	   (else (slib:error "can't coerce to output-port: " arg))))
+   (lambda (output-port)
+     (set! page-height (or page-height (output-port-height output-port)))
+     (set! minimum-break (or minimum-break 0))
+     (let ((output-page 0)
+	   (output-line 0)
+	   (nth-newline-index
+	    (lambda (str n)
+	      (define len (string-length str))
+	      (do ((i 0 (+ i 1)))
+		  ((or (zero? n) (> i len)) (+ -1 i))
+		(cond ((char=? #\newline (string-ref str i))
+		       (set! n (+ -1 n)))))))
+	   (count-newlines
+	    (lambda (str)
+	      (define cnt 0)
+	      (do ((i (+ -1 (string-length str)) (+ -1 i)))
+		  ((negative? i) cnt)
+		(cond ((char=? #\newline (string-ref str i))
+		       (set! cnt (+ 1 cnt)))))))
+	   (format (let ((oformat format))
+		     (lambda (dest fmt arg)
+		       (cond ((not (procedure? fmt)) (oformat dest fmt arg))
+			     ((output-port? dest) (fmt dest arg))
+			     ((eq? #t dest) (fmt (current-output-port) arg))
+			     ((eq? #f dest) (call-with-output-string
+					     (lambda (port) (fmt port arg))))
+			     (else (oformat dest fmt arg)))))))
+       (define column-names (table 'column-names))
+       (define (do-header)
+	 (let ((str (format #f header column-names)))
+	   (display str output-port)
+	   (set! output-line (count-newlines str))))
+       (define (do-lines str inc)
+	 (cond
+	  ((< (+ output-line inc) page-height)
+	   (display str output-port)
+	   (set! output-line (+ output-line inc)))
+	  (else				;outputting footer
+	   (cond ((and (not (zero? minimum-break))
+		       (> cnt (* 2 minimum-break))
+		       (> (- page-height output-line) minimum-break))
+		  (let ((break (nth-newline-index
+				str (- page-height output-line))))
+		    (display (substring str 0 (+ 1 break) output-port))
+		    (set! str (substring str (+ 1 break) (string-length str)))
+		    (set! inc (- inc (- page-height output-line))))))
+	   (format output-port footer column-names)
+	   (display slib:form-feed output-port)
+	   (set! output-page (+ 1 output-page))
+	   (do-header)
+	   (do-lines str inc))))
+
+       (do-header)
+       ((table 'for-each-row)
+	(lambda (row)
+	  (let ((str (format #f reporter row)))
+	    (do-lines str (count-newlines str)))))
+       output-page))))