--- /dev/null
+;;; regi.el --- REGular expression Interpreting engine
+
+;; Author: 1993 Barry A. Warsaw, Century Computing, Inc. <bwarsaw@cen.com>
+;; Maintainer: bwarsaw@cen.com
+;; Created: 24-Feb-1993
+;; Version: 1.8
+;; Last Modified: 1993/06/01 21:33:00
+;; Keywords: regular expression regexp matching text
+
+;; Copyright (C) 1993 Barry A. Warsaw
+
+;; This file is not yet part of GNU Emacs.
+;;
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 2 of the License, or
+;; (at your option) any later version.
+;;
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+;; GNU General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with this program; if not, write to the Free Software
+;; Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+;; LCD Archive Entry
+;; regi|Barry A. Warsaw|bwarsaw@cen.com
+;; |REGular expression Interpreting engine
+;; |1993/06/01 21:33:00|1.8|
+
+;;; Code:
+
+\f
+(defun regi-pos (&optional position col-p)
+ "Return the character position at various buffer positions.
+Optional POSITION can be one of the following symbols:
+
+`bol' == beginning of line
+`boi' == beginning of indentation
+`eol' == end of line [default]
+`bonl' == beginning of next line
+`bopl' == beginning of previous line
+
+Optional COL-P non-nil returns `current-column' instead of character position."
+ (save-excursion
+ (cond
+ ((eq position 'bol) (beginning-of-line))
+ ((eq position 'boi) (back-to-indentation))
+ ((eq position 'bonl) (forward-line 1))
+ ((eq position 'bopl) (forward-line -1))
+ (t (end-of-line)))
+ (if col-p (current-column) (point))))
+
+(defun regi-mapcar (predlist func &optional negate-p case-fold-search-p)
+ "Build a regi frame where each element of PREDLIST appears exactly once.
+The frame contains elements where each member of PREDLIST is
+associated with FUNC, and optionally NEGATE-P and CASE-FOLD-SEARCH-P."
+ (let (frame tail)
+ (if (or negate-p case-fold-search-p)
+ (setq tail (list negate-p)))
+ (if case-fold-search-p
+ (setq tail (append tail (list case-fold-search-p))))
+ (while predlist
+ (let ((element (list (car predlist) func)))
+ (if tail
+ (setq element (append element tail)))
+ (setq frame (append frame (list element))
+ predlist (cdr predlist))
+ ))
+ frame))
+
+\f
+(defun regi-interpret (frame &optional start end)
+ "Interpret the regi frame FRAME.
+If optional START and END are supplied, they indicate the region of
+interest, and the buffer is narrowed to the beginning of the line
+containing START, and beginning of the line after the line containing
+END. Otherwise, point and mark are not set and processing continues
+until your FUNC returns the `abort' symbol (see below). Beware! Not
+supplying a START or END could put you in an infinite loop.
+
+A regi frame is a list of entries of the form:
+
+ (PRED FUNC [NEGATE-P [CASE-FOLD-SEARCH]])
+
+PRED is a predicate against which each line in the region is tested,
+and if a match occurs, FUNC is `eval'd. Point is then moved to the
+beginning of the next line, the frame is reset and checking continues.
+If a match doesn't occur, the next entry is checked against the
+current line until all entries in the frame are checked. At this
+point, if no match occurred, the frame is reset and point is moved to
+the next line. Checking continues until every line in the region is
+checked. Optional NEGATE-P inverts the result of PRED before FUNC is
+called and `case-fold-search' is bound to the optional value of
+CASE-FOLD-SEARCH for the PRED check.
+
+PRED can be a string, variable, function or one of the following
+symbols: t, nil, `begin', `end', and `every'. If PRED is a string, or
+a variable or list that evaluates to a string, it is interpreted as a
+regular expression and is matched against the current line (from the
+beginning) using `looking-at'. If PRED does not evaluate to a string,
+it is interpreted as a binary value (nil or non-nil).
+
+PRED can also be one of the following symbols:
+
+t -- always produces a true outcome
+`begin' -- always executes before anything else
+`end' -- always executes after everything else
+`every' -- execute after frame is matched on a line
+
+Note that NEGATE-P and CASE-FOLD-SEARCH are meaningless if PRED is one
+of these special symbols. Only the first occurance of each symbol in
+a frame entry is used, the rest are ignored.
+
+Your FUNC can return values which control regi processing. If a list
+is returned from your function, it can contain any combination of the
+following elements:
+
+the symbol `continue'
+ Tells regi to continue processing frame-entries after a match,
+ instead of resetting to the first entry and advancing to the next
+ line, as is the default behavior. When returning this symbol,
+ you must take care not to enter an infinite loop.
+
+the symbol `abort'
+ Tells regi to terminate processing this frame. any end
+ frame-entry is still processed.
+
+the list `(frame . NEWFRAME)'
+ Tells regi to use NEWFRAME as its current frame. In other words,
+ your FUNC can modify the executing regi frame on the fly.
+
+the list `(step . STEP)'
+ Tells regi to move STEP number of lines forward during normal
+ processing. By default, regi moves forward 1 line. STEP can be
+ negative, but be careful of infinite loops.
+
+You should usually take care to explicitly return nil from your
+function if no action is to take place. Your FUNC will always be
+`eval'ed. The following variables will be temporarily bound to some
+useful information:
+
+`curline'
+ the current line in the buffer, as a string
+
+`curframe'
+ the full, current frame being executed
+
+`curentry'
+ the current frame entry being executed."
+
+ (save-excursion
+ (save-restriction
+ (let (begin-tag end-tag every-tag current-frame working-frame donep)
+
+ ;; set up the narrowed region
+ (and start
+ end
+ (let* ((tstart start)
+ (start (min start end))
+ (end (max start end)))
+ (narrow-to-region
+ (progn (goto-char end) (regi-pos 'bonl))
+ (progn (goto-char start) (regi-pos 'bol)))))
+
+ ;; lets find the special tags and remove them from the working
+ ;; frame. note that only the last special tag is used.
+ (mapcar
+ (function
+ (lambda (entry)
+ (let ((pred (car entry))
+ (func (car (cdr entry))))
+ (cond
+ ((eq pred 'begin) (setq begin-tag func))
+ ((eq pred 'end) (setq end-tag func))
+ ((eq pred 'every) (setq every-tag func))
+ (t
+ (setq working-frame (append working-frame (list entry))))
+ ) ; end-cond
+ )))
+ frame) ; end-mapcar
+
+ ;; execute the begin entry
+ (eval begin-tag)
+
+ ;; now process the frame
+ (setq current-frame working-frame)
+ (while (not (or donep (eobp)))
+ (let* ((entry (car current-frame))
+ (pred (nth 0 entry))
+ (func (nth 1 entry))
+ (negate-p (nth 2 entry))
+ (case-fold-search (nth 3 entry))
+ match-p)
+ (catch 'regi-throw-top
+ (cond
+ ;; we are finished processing the frame for this line
+ ((not current-frame)
+ (setq current-frame working-frame) ;reset frame
+ (forward-line 1)
+ (throw 'regi-throw-top t))
+ ;; see if predicate evaluates to a string
+ ((stringp (setq match-p (eval pred)))
+ (setq match-p (looking-at match-p)))
+ ) ; end-cond
+
+ ;; now that we've done the initial matching, check for
+ ;; negation of match
+ (and negate-p
+ (setq match-p (not match-p)))
+
+ ;; if the line matched, package up the argument list and
+ ;; funcall the FUNC
+ (if match-p
+ (let* ((curline (buffer-substring
+ (regi-pos 'bol)
+ (regi-pos 'eol)))
+ (curframe current-frame)
+ (curentry entry)
+ (result (eval func))
+ (step (or (cdr (assq 'step result)) 1))
+ )
+ ;; changing frame on the fly?
+ (if (assq 'frame result)
+ (setq working-frame (cdr (assq 'frame result))))
+
+ ;; continue processing current frame?
+ (if (memq 'continue result)
+ (setq current-frame (cdr current-frame))
+ (forward-line step)
+ (setq current-frame working-frame))
+
+ ;; abort current frame?
+ (if (memq 'abort result)
+ (progn
+ (setq donep t)
+ (throw 'regi-throw-top t)))
+ ) ; end-let
+
+ ;; else if no match occurred, then process the next
+ ;; frame-entry on the current line
+ (setq current-frame (cdr current-frame))
+
+ ) ; end-if match-p
+ ) ; end catch
+ ) ; end let
+
+ ;; after every cycle, evaluate every-tag
+ (eval every-tag)
+ ) ; end-while
+
+ ;; now process the end entry
+ (eval end-tag)))))
+
+\f
+(provide 'regi)
+;;; regi.el ends here
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