-;; cust-print.el -- handles print-level and print-circle.
-
-;; Copyright (C) 1992 Free Software Foundation, Inc.
-
-;; Author: Daniel LaLiberte <liberte@cs.uiuc.edu>
-;; Version: 1.0
-;; Adapted-By: ESR
-;; Keyword: extensions
-
-;; This file is part of GNU Emacs.
-
-;; GNU Emacs 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, or (at your option)
-;; any later version.
-
-;; GNU Emacs 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 GNU Emacs; see the file COPYING. If not, write to
-;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
-
-;;; Commentary:
-
-;; This package provides a general print handler for prin1 and princ
-;; that supports print-level and print-circle, and by the way,
-;; print-length since the standard routines are being replaced. Also,
-;; to print custom types constructed from lists and vectors, use
-;; custom-print-list and custom-print-vector. See the documentation
-;; strings of these variables for more details.
-
-;; If the results of your expressions contain circular references to
-;; other parts of the same structure, the standard Emacs print
-;; subroutines may fail to print with an untrappable error,
-;; "Apparently circular structure being printed". If you only use cdr
-;; circular lists (where cdrs of lists point back; what is the right
-;; term here?), you can limit the length of printing with
-;; print-length. But car circular lists and circular vectors generate
-;; the above mentioned untrappable error in Emacs version 18. Version
-;; 19 will support print-level, but it is often useful to get a better
-;; print representation of circular structures; the print-circle
-;; option may be used to print more concise representations.
-
-;; There are two main ways to use this package. First, you may
-;; replace prin1, princ, and some subroutines that use them by calling
-;; install-custom-print-funcs so that any use of these functions in
-;; lisp code will be affected. Second, you could call the custom
-;; routines directly, thus only affecting the printing that requires
-;; them.
-
-;; Note that subroutines which call print subroutines directly will not
-;; use the custom print functions. In particular, the evaluation
-;; functions like eval-region call the print subroutines directly.
-;; Therefore, evaluating (aref circ-list 0), which calls error
-;; directly (because circ-list is not an array), will jump to the top
-;; level instead of printing the circular list.
-
-;; Obviously the right way to implement this custom-print facility
-;; is in C. Please volunteer since I don't have the time or need.
-
-;; Implementation design: we want to use the same list and vector
-;; processing algorithm for all versions of prin1 and princ, since how
-;; the processing is done depends on print-length, print-level, and
-;; print-circle. For circle printing, a preprocessing step is
-;; required before the final printing. Thanks to Jamie Zawinski
-;; for motivation and algorithms.
-
-;;=========================================================
-;; export list:
-
-;; print-level
-;; print-circle
-
-;; custom-print-list
-;; custom-print-vector
-;; add-custom-print-list
-;; add-custom-print-vector
-
-;; install-custom-print-funcs
-;; uninstall-custom-print-funcs
-
-;; custom-prin1
-;; custom-princ
-;; custom-prin1-to-string
-;; custom-print
-;; custom-format
-;; custom-message
-;; custom-error
-
-;;; Code:
-
-(provide 'custom-print)
-;; Abbreviated package name: "CP"
-
-;;(defvar print-length nil
-;; "*Controls how many elements of a list, at each level, are printed.
-;;This is defined by emacs.")
-
-(defvar print-level nil
- "*Controls how many levels deep a nested data object will print.
-
-If nil, printing proceeds recursively and may lead to
-max-lisp-eval-depth being exceeded or an untrappable error may occur:
-\"Apparently circular structure being printed.\" Also see
-print-length and print-circle.
-
-If non-nil, components at levels equal to or greater than print-level
-are printed simply as \"#\". The object to be printed is at level 0,
-and if the object is a list or vector, its top-level components are at
-level 1.")
-
-
-(defvar print-circle nil
- "*Controls the printing of recursive structures.
-
-If nil, printing proceeds recursively and may lead to
-max-lisp-eval-depth being exceeded or an untrappable error may occur:
-\"Apparently circular structure being printed.\" Also see
-print-length and print-level.
-
-If non-nil, shared substructures anywhere in the structure are printed
-with \"#n=\" before the first occurance (in the order of the print
-representation) and \"#n#\" in place of each subsequent occurance,
-where n is a positive decimal integer.
-
-Currently, there is no way to read this representation in Emacs.")
-
-
-(defconst custom-print-list
- nil
- ;; e.g. '((floatp . float-to-string))
- "If non-nil, an alist for printing of custom list objects.
-Pairs are of the form (pred . converter). If the predicate is true
-for an object, the converter is called with the object and should
-return a string which will be printed with princ.
-Also see custom-print-vector.")
-
-(defconst custom-print-vector
- nil
- "If non-nil, an alist for printing of custom vector objects.
-Pairs are of the form (pred . converter). If the predicate is true
-for an object, the converter is called with the object and should
-return a string which will be printed with princ.
-Also see custom-print-list.")
-
-
-(defun add-custom-print-list (pred converter)
- "Add the pair, a PREDICATE and a CONVERTER, to custom-print-list.
-Any pair that has the same PREDICATE is first removed."
- (setq custom-print-list (cons (cons pred converter)
- (delq (assq pred custom-print-list)
- custom-print-list))))
-;; e.g. (add-custom-print-list 'floatp 'float-to-string)
-
-
-(defun add-custom-print-vector (pred converter)
- "Add the pair, a PREDICATE and a CONVERTER, to custom-print-vector.
-Any pair that has the same PREDICATE is first removed."
- (setq custom-print-vector (cons (cons pred converter)
- (delq (assq pred custom-print-vector)
- custom-print-vector))))
-
-
-;;====================================================
-;; Saving and restoring internal printing routines.
-
-(defun CP::set-function-cell (symbol-pair)
- (fset (car symbol-pair)
- (symbol-function (car (cdr symbol-pair)))))
-
-
-(if (not (fboundp 'CP::internal-prin1))
- (mapcar 'CP::set-function-cell
- '((CP::internal-prin1 prin1)
- (CP::internal-princ princ)
- (CP::internal-print print)
- (CP::internal-prin1-to-string prin1-to-string)
- (CP::internal-format format)
- (CP::internal-message message)
- (CP::internal-error error))))
-
-
-(defun install-custom-print-funcs ()
- "Replace print functions with general, customizable, lisp versions.
-The internal subroutines are saved away and may be recovered with
-uninstall-custom-print-funcs."
- (interactive)
- (mapcar 'CP::set-function-cell
- '((prin1 custom-prin1)
- (princ custom-princ)
- (print custom-print)
- (prin1-to-string custom-prin1-to-string)
- (format custom-format)
- (message custom-message)
- (error custom-error)
- )))
-
-(defun uninstall-custom-print-funcs ()
- "Reset print functions to their internal subroutines."
- (interactive)
- (mapcar 'CP::set-function-cell
- '((prin1 CP::internal-prin1)
- (princ CP::internal-princ)
- (print CP::internal-print)
- (prin1-to-string CP::internal-prin1-to-string)
- (format CP::internal-format)
- (message CP::internal-message)
- (error CP::internal-error)
- )))
-
-
-;;===============================================================
-;; Lisp replacements for prin1 and princ and for subrs that use prin1
-;; (or princ) -- so far only the printing and formatting subrs.
-
-(defun custom-prin1 (object &optional stream)
- "Replacement for standard prin1.
-Uses the appropriate printer depending on the values of print-level
-and print-circle (which see).
-
-Output the printed representation of OBJECT, any Lisp object.
-Quoting characters are printed when needed to make output that `read'
-can handle, whenever this is possible.
-Output stream is STREAM, or value of `standard-output' (which see)."
- (CP::top-level object stream 'CP::internal-prin1))
-
-
-(defun custom-princ (object &optional stream)
- "Same as custom-prin1 except no quoting."
- (CP::top-level object stream 'CP::internal-princ))
-
-(defun custom-prin1-to-string-func (c)
- "Stream function for custom-prin1-to-string."
- (setq prin1-chars (cons c prin1-chars)))
-
-(defun custom-prin1-to-string (object)
- "Replacement for standard prin1-to-string."
- (let ((prin1-chars nil))
- (custom-prin1 object 'custom-prin1-to-string-func)
- (concat (nreverse prin1-chars))))
-
-
-(defun custom-print (object &optional stream)
- "Replacement for standard print."
- (CP::internal-princ "\n")
- (custom-prin1 object stream)
- (CP::internal-princ "\n"))
-
-
-(defun custom-format (fmt &rest args)
- "Replacement for standard format.
-
-Calls format after first making strings for list or vector args.
-The format specification for such args should be %s in any case, so a
-string argument will also work. The string is generated with
-custom-prin1-to-string, which quotes quotable characters."
- (apply 'CP::internal-format fmt
- (mapcar (function (lambda (arg)
- (if (or (listp arg) (vectorp arg))
- (custom-prin1-to-string arg)
- arg)))
- args)))
-
-
-
-(defun custom-message (fmt &rest args)
- "Replacement for standard message that works like custom-format."
- ;; It doesnt work to princ the result of custom-format
- ;; because the echo area requires special handling
- ;; to avoid duplicating the output. CP::internal-message does it right.
- ;; (CP::internal-princ (apply 'custom-format fmt args))
- (apply 'CP::internal-message fmt
- (mapcar (function (lambda (arg)
- (if (or (listp arg) (vectorp arg))
- (custom-prin1-to-string arg)
- arg)))
- args)))
-
-
-(defun custom-error (fmt &rest args)
- "Replacement for standard error that uses custom-format"
- (signal 'error (list (apply 'custom-format fmt args))))
-
-
-;;=========================================
-;; Support for custom prin1 and princ
-
-(defun CP::top-level (object stream internal-printer)
- "Set up for printing."
- (let ((standard-output (or stream standard-output))
- (circle-table (and print-circle (CP::preprocess-circle-tree object)))
- (level (or print-level -1))
- )
-
- (fset 'CP::internal-printer internal-printer)
- (fset 'CP::low-level-prin
- (cond
- ((or custom-print-list
- custom-print-vector
- print-level ; comment out for version 19
- )
- 'CP::custom-object)
- (circle-table
- 'CP::object)
- (t 'CP::internal-printer)))
- (fset 'CP::prin (if circle-table 'CP::circular 'CP::low-level-prin))
-
- (CP::prin object)
- object))
-
-
-(defun CP::object (object)
- "Test object type and print accordingly."
- ;; Could be called as either CP::low-level-prin or CP::prin.
- (cond
- ((null object) (CP::internal-printer object))
- ((consp object) (CP::list object))
- ((vectorp object) (CP::vector object))
- ;; All other types, just print.
- (t (CP::internal-printer object))))
-
-
-(defun CP::custom-object (object)
- "Test object type and print accordingly."
- ;; Could be called as either CP::low-level-prin or CP::prin.
- (cond
- ((null object) (CP::internal-printer object))
-
- ((consp object)
- (or (and custom-print-list
- (CP::custom-object1 object custom-print-list))
- (CP::list object)))
-
- ((vectorp object)
- (or (and custom-print-vector
- (CP::custom-object1 object custom-print-vector))
- (CP::vector object)))
-
- ;; All other types, just print.
- (t (CP::internal-printer object))))
-
-
-(defun CP::custom-object1 (object alist)
- "Helper for CP::custom-object.
-Print the custom OBJECT using the custom type ALIST.
-For the first predicate that matches the object, the corresponding
-converter is evaluated with the object and the string that results is
-printed with princ. Return nil if no predicte matches the object."
- (while (and alist (not (funcall (car (car alist)) object)))
- (setq alist (cdr alist)))
- ;; If alist is not null, then something matched.
- (if alist
- (CP::internal-princ
- (funcall (cdr (car alist)) object) ; returns string
- )))
-
-
-(defun CP::circular (object)
- "Printer for prin1 and princ that handles circular structures.
-If OBJECT appears multiply, and has not yet been printed,
-prefix with label; if it has been printed, use #n# instead.
-Otherwise, print normally."
- (let ((tag (assq object circle-table)))
- (if tag
- (let ((id (cdr tag)))
- (if (> id 0)
- (progn
- ;; Already printed, so just print id.
- (CP::internal-princ "#")
- (CP::internal-princ id)
- (CP::internal-princ "#"))
- ;; Not printed yet, so label with id and print object.
- (setcdr tag (- id)) ; mark it as printed
- (CP::internal-princ "#")
- (CP::internal-princ (- id))
- (CP::internal-princ "=")
- (CP::low-level-prin object)
- ))
- ;; Not repeated in structure.
- (CP::low-level-prin object))))
-
-
-;;================================================
-;; List and vector processing for print functions.
-
-(defun CP::list (list)
- "Print a list using print-length, print-level, and print-circle."
- (if (= level 0)
- (CP::internal-princ "#")
- (let ((level (1- level)))
- (CP::internal-princ "(")
- (let ((length (or print-length 0)))
-
- ;; Print the first element always (even if length = 0).
- (CP::prin (car list))
- (setq list (cdr list))
- (if list (CP::internal-princ " "))
- (setq length (1- length))
-
- ;; Print the rest of the elements.
- (while (and list (/= 0 length))
- (if (and (listp list)
- (not (assq list circle-table)))
- (progn
- (CP::prin (car list))
- (setq list (cdr list)))
-
- ;; cdr is not a list, or it is in circle-table.
- (CP::internal-princ ". ")
- (CP::prin list)
- (setq list nil))
-
- (setq length (1- length))
- (if list (CP::internal-princ " ")))
-
- (if (and list (= length 0)) (CP::internal-princ "..."))
- (CP::internal-princ ")"))))
- list)
-
-
-(defun CP::vector (vector)
- "Print a vector using print-length, print-level, and print-circle."
- (if (= level 0)
- (CP::internal-princ "#")
- (let ((level (1- level))
- (i 0)
- (len (length vector)))
- (CP::internal-princ "[")
-
- (if print-length
- (setq len (min print-length len)))
- ;; Print the elements
- (while (< i len)
- (CP::prin (aref vector i))
- (setq i (1+ i))
- (if (< i (length vector)) (CP::internal-princ " ")))
-
- (if (< i (length vector)) (CP::internal-princ "..."))
- (CP::internal-princ "]")
- ))
- vector)
-
-
-;;==================================
-;; Circular structure preprocessing
-
-(defun CP::preprocess-circle-tree (object)
- ;; Fill up the table.
- (let (;; Table of tags for each object in an object to be printed.
- ;; A tag is of the form:
- ;; ( <object> <nil-t-or-id-number> )
- ;; The id-number is generated after the entire table has been computed.
- ;; During walk through, the real circle-table lives in the cdr so we
- ;; can use setcdr to add new elements instead of having to setq the
- ;; variable sometimes (poor man's locf).
- (circle-table (list nil)))
- (CP::walk-circle-tree object)
-
- ;; Reverse table so it is in the order that the objects will be printed.
- ;; This pass could be avoided if we always added to the end of the
- ;; table with setcdr in walk-circle-tree.
- (setcdr circle-table (nreverse (cdr circle-table)))
-
- ;; Walk through the table, assigning id-numbers to those
- ;; objects which will be printed using #N= syntax. Delete those
- ;; objects which will be printed only once (to speed up assq later).
- (let ((rest circle-table)
- (id -1))
- (while (cdr rest)
- (let ((tag (car (cdr rest))))
- (cond ((cdr tag)
- (setcdr tag id)
- (setq id (1- id))
- (setq rest (cdr rest)))
- ;; Else delete this object.
- (t (setcdr rest (cdr (cdr rest))))))
- ))
- ;; Drop the car.
- (cdr circle-table)
- ))
-
-
-
-(defun CP::walk-circle-tree (object)
- (let (read-equivalent-p tag)
- (while object
- (setq read-equivalent-p (or (numberp object) (symbolp object))
- tag (and (not read-equivalent-p)
- (assq object (cdr circle-table))))
- (cond (tag
- ;; Seen this object already, so note that.
- (setcdr tag t))
-
- ((not read-equivalent-p)
- ;; Add a tag for this object.
- (setcdr circle-table
- (cons (list object)
- (cdr circle-table)))))
- (setq object
- (cond
- (tag ;; No need to descend since we have already.
- nil)
-
- ((consp object)
- ;; Walk the car of the list recursively.
- (CP::walk-circle-tree (car object))
- ;; But walk the cdr with the above while loop
- ;; to avoid problems with max-lisp-eval-depth.
- ;; And it should be faster than recursion.
- (cdr object))
-
- ((vectorp object)
- ;; Walk the vector.
- (let ((i (length object))
- (j 0))
- (while (< j i)
- (CP::walk-circle-tree (aref object j))
- (setq j (1+ j))))))))))
-
-
-
-;;=======================================
-
-(quote
- examples
-
- (progn
- ;; Create some circular structures.
- (setq circ-sym (let ((x (make-symbol "FOO"))) (list x x)))
- (setq circ-list (list 'a 'b (vector 1 2 3 4) 'd 'e 'f))
- (setcar (nthcdr 3 circ-list) circ-list)
- (aset (nth 2 circ-list) 2 circ-list)
- (setq dotted-circ-list (list 'a 'b 'c))
- (setcdr (cdr (cdr dotted-circ-list)) dotted-circ-list)
- (setq circ-vector (vector 1 2 3 4 (list 'a 'b 'c 'd) 6 7))
- (aset circ-vector 5 (make-symbol "-gensym-"))
- (setcar (cdr (aref circ-vector 4)) (aref circ-vector 5))
- nil)
-
- (install-custom-print-funcs)
- ;; (setq print-circle t)
-
- (let ((print-circle t))
- (or (equal (prin1-to-string circ-list) "#1=(a b [1 2 #1# 4] #1# e f)")
- (error "circular object with array printing")))
-
- (let ((print-circle t))
- (or (equal (prin1-to-string dotted-circ-list) "#1=(a b c . #1#)")
- (error "circular object with array printing")))
-
- (let* ((print-circle t)
- (x (list 'p 'q))
- (y (list (list 'a 'b) x 'foo x)))
- (setcdr (cdr (cdr (cdr y))) (cdr y))
- (or (equal (prin1-to-string y) "((a b) . #1=(#2=(p q) foo #2# . #1#))"
- )
- (error "circular list example from CL manual")))
-
- ;; There's no special handling of uninterned symbols in custom-print.
- (let ((print-circle nil))
- (or (equal (prin1-to-string circ-sym) "(#:FOO #:FOO)")
- (error "uninterned symbols in list")))
- (let ((print-circle t))
- (or (equal (prin1-to-string circ-sym) "(#1=FOO #1#)")
- (error "circular uninterned symbols in list")))
-
- (uninstall-custom-print-funcs)
- )
-
-;;; cust-print.el ends here
+;;; cust-print.el --- handles print-level and print-circle
+
+;; Copyright (C) 1992 Free Software Foundation, Inc.
+
+;; Author: Daniel LaLiberte <liberte@holonexus.org>
+;; Adapted-By: ESR
+;; Keywords: extensions
+
+;; LCD Archive Entry:
+;; cust-print|Daniel LaLiberte|liberte@holonexus.org
+;; |Handle print-level, print-circle and more.
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs 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, or (at your option)
+;; any later version.
+
+;; GNU Emacs 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 GNU Emacs; see the file COPYING. If not, write to the
+;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+;; Boston, MA 02111-1307, USA.
+
+;;; Commentary:
+
+;; This package provides a general print handler for prin1 and princ
+;; that supports print-level and print-circle, and by the way,
+;; print-length since the standard routines are being replaced. Also,
+;; to print custom types constructed from lists and vectors, use
+;; custom-print-list and custom-print-vector. See the documentation
+;; strings of these variables for more details.
+
+;; If the results of your expressions contain circular references to
+;; other parts of the same structure, the standard Emacs print
+;; subroutines may fail to print with an untrappable error,
+;; "Apparently circular structure being printed". If you only use cdr
+;; circular lists (where cdrs of lists point back; what is the right
+;; term here?), you can limit the length of printing with
+;; print-length. But car circular lists and circular vectors generate
+;; the above mentioned error in Emacs version 18. Version
+;; 19 supports print-level, but it is often useful to get a better
+;; print representation of circular and shared structures; the print-circle
+;; option may be used to print more concise representations.
+
+;; There are three main ways to use this package. First, you may
+;; replace prin1, princ, and some subroutines that use them by calling
+;; install-custom-print so that any use of these functions in
+;; Lisp code will be affected; you can later reset with
+;; uninstall-custom-print. Second, you may temporarily install
+;; these functions with the macro with-custom-print. Third, you
+;; could call the custom routines directly, thus only affecting the
+;; printing that requires them.
+
+;; Note that subroutines which call print subroutines directly will
+;; not use the custom print functions. In particular, the evaluation
+;; functions like eval-region call the print subroutines directly.
+;; Therefore, if you evaluate (aref circ-list 0), where circ-list is a
+;; circular list rather than an array, aref calls error directly which
+;; will jump to the top level instead of printing the circular list.
+
+;; Uninterned symbols are recognized when print-circle is non-nil,
+;; but they are not printed specially here. Use the cl-packages package
+;; to print according to print-gensym.
+
+;; Obviously the right way to implement this custom-print facility is
+;; in C or with hooks into the standard printer. Please volunteer
+;; since I don't have the time or need. More CL-like printing
+;; capabilities could be added in the future.
+
+;; Implementation design: we want to use the same list and vector
+;; processing algorithm for all versions of prin1 and princ, since how
+;; the processing is done depends on print-length, print-level, and
+;; print-circle. For circle printing, a preprocessing step is
+;; required before the final printing. Thanks to Jamie Zawinski
+;; for motivation and algorithms.
+
+\f
+;;; Code:
+
+(defgroup cust-print nil
+ "Handles print-level and print-circle."
+ :prefix "print-"
+ :group 'lisp
+ :group 'extensions)
+
+;; If using cl-packages:
+
+'(defpackage "cust-print"
+ (:nicknames "CP" "custom-print")
+ (:use "el")
+ (:export
+ print-level
+ print-circle
+
+ custom-print-install
+ custom-print-uninstall
+ custom-print-installed-p
+ with-custom-print
+
+ custom-prin1
+ custom-princ
+ custom-prin1-to-string
+ custom-print
+ custom-format
+ custom-message
+ custom-error
+
+ custom-printers
+ add-custom-printer
+ ))
+
+'(in-package cust-print)
+
+;; Emacs 18 doesn't have defalias.
+;; Provide def for byte compiler.
+(eval-and-compile
+ (or (fboundp 'defalias) (fset 'defalias 'fset)))
+
+\f
+;; Variables:
+;;=========================================================
+
+;;(defvar print-length nil
+;; "*Controls how many elements of a list, at each level, are printed.
+;;This is defined by emacs.")
+
+(defcustom print-level nil
+ "*Controls how many levels deep a nested data object will print.
+
+If nil, printing proceeds recursively and may lead to
+max-lisp-eval-depth being exceeded or an error may occur:
+`Apparently circular structure being printed.'
+Also see `print-length' and `print-circle'.
+
+If non-nil, components at levels equal to or greater than `print-level'
+are printed simply as `#'. The object to be printed is at level 0,
+and if the object is a list or vector, its top-level components are at
+level 1."
+ :type '(choice (const nil) integer)
+ :group 'cust-print)
+
+
+(defcustom print-circle nil
+ "*Controls the printing of recursive structures.
+
+If nil, printing proceeds recursively and may lead to
+`max-lisp-eval-depth' being exceeded or an error may occur:
+\"Apparently circular structure being printed.\" Also see
+`print-length' and `print-level'.
+
+If non-nil, shared substructures anywhere in the structure are printed
+with `#N=' before the first occurrence (in the order of the print
+representation) and `#N#' in place of each subsequent occurrence,
+where N is a positive decimal integer.
+
+There is no way to read this representation in standard Emacs,
+but if you need to do so, try the cl-read.el package."
+ :type 'boolean
+ :group 'cust-print)
+
+
+(defcustom custom-print-vectors nil
+ "*Non-nil if printing of vectors should obey print-level and print-length.
+
+For Emacs 18, setting print-level, or adding custom print list or
+vector handling will make this happen anyway. Emacs 19 obeys
+print-level, but not for vectors."
+ :type 'boolean
+ :group 'cust-print)
+
+\f
+;; Custom printers
+;;==========================================================
+
+(defconst custom-printers nil
+ ;; e.g. '((symbolp . pkg::print-symbol))
+ "An alist for custom printing of any type.
+Pairs are of the form (PREDICATE . PRINTER). If PREDICATE is true
+for an object, then PRINTER is called with the object.
+PRINTER should print to `standard-output' using cust-print-original-princ
+if the standard printer is sufficient, or cust-print-prin for complex things.
+The PRINTER should return the object being printed.
+
+Don't modify this variable directly. Use `add-custom-printer' and
+`delete-custom-printer'")
+;; Should cust-print-original-princ and cust-print-prin be exported symbols?
+;; Or should the standard printers functions be replaced by
+;; CP ones in Emacs Lisp so that CP internal functions need not be called?
+
+(defun add-custom-printer (pred printer)
+ "Add a pair of PREDICATE and PRINTER to `custom-printers'.
+Any pair that has the same PREDICATE is first removed."
+ (setq custom-printers (cons (cons pred printer)
+ (delq (assq pred custom-printers)
+ custom-printers)))
+ ;; Rather than updating here, we could wait until cust-print-top-level is called.
+ (cust-print-update-custom-printers))
+
+(defun delete-custom-printer (pred)
+ "Delete the custom printer associated with PREDICATE."
+ (setq custom-printers (delq (assq pred custom-printers)
+ custom-printers))
+ (cust-print-update-custom-printers))
+
+
+(defun cust-print-use-custom-printer (object)
+ ;; Default function returns nil.
+ nil)
+
+(defun cust-print-update-custom-printers ()
+ ;; Modify the definition of cust-print-use-custom-printer
+ (defalias 'cust-print-use-custom-printer
+ ;; We don't really want to require the byte-compiler.
+ ;; (byte-compile
+ `(lambda (object)
+ (cond
+ ,@(mapcar (function
+ (lambda (pair)
+ `((,(car pair) object)
+ (,(cdr pair) object))))
+ custom-printers)
+ ;; Otherwise return nil.
+ (t nil)
+ ))
+ ;; )
+ ))
+
+\f
+;; Saving and restoring emacs printing routines.
+;;====================================================
+
+(defun cust-print-set-function-cell (symbol-pair)
+ (defalias (car symbol-pair)
+ (symbol-function (car (cdr symbol-pair)))))
+
+(defun cust-print-original-princ (object &optional stream)) ; dummy def
+
+;; Save emacs routines.
+(if (not (fboundp 'cust-print-original-prin1))
+ (mapcar 'cust-print-set-function-cell
+ '((cust-print-original-prin1 prin1)
+ (cust-print-original-princ princ)
+ (cust-print-original-print print)
+ (cust-print-original-prin1-to-string prin1-to-string)
+ (cust-print-original-format format)
+ (cust-print-original-message message)
+ (cust-print-original-error error))))
+
+
+(defun custom-print-install ()
+ "Replace print functions with general, customizable, Lisp versions.
+The emacs subroutines are saved away, and you can reinstall them
+by running `custom-print-uninstall'."
+ (interactive)
+ (mapcar 'cust-print-set-function-cell
+ '((prin1 custom-prin1)
+ (princ custom-princ)
+ (print custom-print)
+ (prin1-to-string custom-prin1-to-string)
+ (format custom-format)
+ (message custom-message)
+ (error custom-error)
+ ))
+ t)
+
+(defun custom-print-uninstall ()
+ "Reset print functions to their emacs subroutines."
+ (interactive)
+ (mapcar 'cust-print-set-function-cell
+ '((prin1 cust-print-original-prin1)
+ (princ cust-print-original-princ)
+ (print cust-print-original-print)
+ (prin1-to-string cust-print-original-prin1-to-string)
+ (format cust-print-original-format)
+ (message cust-print-original-message)
+ (error cust-print-original-error)
+ ))
+ t)
+
+(defalias 'custom-print-funcs-installed-p 'custom-print-installed-p)
+(defun custom-print-installed-p ()
+ "Return t if custom-print is currently installed, nil otherwise."
+ (eq (symbol-function 'custom-prin1) (symbol-function 'prin1)))
+
+(put 'with-custom-print-funcs 'edebug-form-spec '(body))
+(put 'with-custom-print 'edebug-form-spec '(body))
+
+(defalias 'with-custom-print-funcs 'with-custom-print)
+(defmacro with-custom-print (&rest body)
+ "Temporarily install the custom print package while executing BODY."
+ `(unwind-protect
+ (progn
+ (custom-print-install)
+ ,@body)
+ (custom-print-uninstall)))
+
+\f
+;; Lisp replacements for prin1 and princ, and for some subrs that use them
+;;===============================================================
+;; - so far only the printing and formatting subrs.
+
+(defun custom-prin1 (object &optional stream)
+ "Output the printed representation of OBJECT, any Lisp object.
+Quoting characters are printed when needed to make output that `read'
+can handle, whenever this is possible.
+Output stream is STREAM, or value of `standard-output' (which see).
+
+This is the custom-print replacement for the standard `prin1'. It
+uses the appropriate printer depending on the values of `print-level'
+and `print-circle' (which see)."
+ (cust-print-top-level object stream 'cust-print-original-prin1))
+
+
+(defun custom-princ (object &optional stream)
+ "Output the printed representation of OBJECT, any Lisp object.
+No quoting characters are used; no delimiters are printed around
+the contents of strings.
+Output stream is STREAM, or value of `standard-output' (which see).
+
+This is the custom-print replacement for the standard `princ'."
+ (cust-print-top-level object stream 'cust-print-original-princ))
+
+
+(defun custom-prin1-to-string (object &optional noescape)
+ "Return a string containing the printed representation of OBJECT,
+any Lisp object. Quoting characters are used when needed to make output
+that `read' can handle, whenever this is possible, unless the optional
+second argument NOESCAPE is non-nil.
+
+This is the custom-print replacement for the standard `prin1-to-string'."
+ (let ((buf (get-buffer-create " *custom-print-temp*")))
+ ;; We must erase the buffer before printing in case an error
+ ;; occurred during the last prin1-to-string and we are in debugger.
+ (save-excursion
+ (set-buffer buf)
+ (erase-buffer))
+ ;; We must be in the current-buffer when the print occurs.
+ (if noescape
+ (custom-princ object buf)
+ (custom-prin1 object buf))
+ (save-excursion
+ (set-buffer buf)
+ (buffer-string)
+ ;; We could erase the buffer again, but why bother?
+ )))
+
+
+(defun custom-print (object &optional stream)
+ "Output the printed representation of OBJECT, with newlines around it.
+Quoting characters are printed when needed to make output that `read'
+can handle, whenever this is possible.
+Output stream is STREAM, or value of `standard-output' (which see).
+
+This is the custom-print replacement for the standard `print'."
+ (cust-print-original-princ "\n" stream)
+ (custom-prin1 object stream)
+ (cust-print-original-princ "\n" stream))
+
+
+(defun custom-format (fmt &rest args)
+ "Format a string out of a control-string and arguments.
+The first argument is a control string. It, and subsequent arguments
+substituted into it, become the value, which is a string.
+It may contain %s or %d or %c to substitute successive following arguments.
+%s means print an argument as a string, %d means print as number in decimal,
+%c means print a number as a single character.
+The argument used by %s must be a string or a symbol;
+the argument used by %d, %b, %o, %x or %c must be a number.
+
+This is the custom-print replacement for the standard `format'. It
+calls the emacs `format' after first making strings for list,
+vector, or symbol args. The format specification for such args should
+be `%s' in any case, so a string argument will also work. The string
+is generated with `custom-prin1-to-string', which quotes quotable
+characters."
+ (apply 'cust-print-original-format fmt
+ (mapcar (function (lambda (arg)
+ (if (or (listp arg) (vectorp arg) (symbolp arg))
+ (custom-prin1-to-string arg)
+ arg)))
+ args)))
+
+
+(defun custom-message (fmt &rest args)
+ "Print a one-line message at the bottom of the screen.
+The first argument is a control string.
+It may contain %s or %d or %c to print successive following arguments.
+%s means print an argument as a string, %d means print as number in decimal,
+%c means print a number as a single character.
+The argument used by %s must be a string or a symbol;
+the argument used by %d or %c must be a number.
+
+This is the custom-print replacement for the standard `message'.
+See `custom-format' for the details."
+ ;; It doesn't work to princ the result of custom-format as in:
+ ;; (cust-print-original-princ (apply 'custom-format fmt args))
+ ;; because the echo area requires special handling
+ ;; to avoid duplicating the output.
+ ;; cust-print-original-message does it right.
+ (apply 'cust-print-original-message fmt
+ (mapcar (function (lambda (arg)
+ (if (or (listp arg) (vectorp arg) (symbolp arg))
+ (custom-prin1-to-string arg)
+ arg)))
+ args)))
+
+
+(defun custom-error (fmt &rest args)
+ "Signal an error, making error message by passing all args to `format'.
+
+This is the custom-print replacement for the standard `error'.
+See `custom-format' for the details."
+ (signal 'error (list (apply 'custom-format fmt args))))
+
+
+\f
+;; Support for custom prin1 and princ
+;;=========================================
+
+;; Defs to quiet byte-compiler.
+(defvar circle-table)
+(defvar cust-print-current-level)
+
+(defun cust-print-original-printer (object)) ; One of the standard printers.
+(defun cust-print-low-level-prin (object)) ; Used internally.
+(defun cust-print-prin (object)) ; Call this to print recursively.
+
+(defun cust-print-top-level (object stream emacs-printer)
+ ;; Set up for printing.
+ (let ((standard-output (or stream standard-output))
+ ;; circle-table will be non-nil if anything is circular.
+ (circle-table (and print-circle
+ (cust-print-preprocess-circle-tree object)))
+ (cust-print-current-level (or print-level -1)))
+
+ (defalias 'cust-print-original-printer emacs-printer)
+ (defalias 'cust-print-low-level-prin
+ (cond
+ ((or custom-printers
+ circle-table
+ print-level ; comment out for version 19
+ ;; Emacs doesn't use print-level or print-length
+ ;; for vectors, but custom-print can.
+ (if custom-print-vectors
+ (or print-level print-length)))
+ 'cust-print-print-object)
+ (t 'cust-print-original-printer)))
+ (defalias 'cust-print-prin
+ (if circle-table 'cust-print-print-circular 'cust-print-low-level-prin))
+
+ (cust-print-prin object)
+ object))
+
+
+(defun cust-print-print-object (object)
+ ;; Test object type and print accordingly.
+ ;; Could be called as either cust-print-low-level-prin or cust-print-prin.
+ (cond
+ ((null object) (cust-print-original-printer object))
+ ((cust-print-use-custom-printer object) object)
+ ((consp object) (cust-print-list object))
+ ((vectorp object) (cust-print-vector object))
+ ;; All other types, just print.
+ (t (cust-print-original-printer object))))
+
+
+(defun cust-print-print-circular (object)
+ ;; Printer for `prin1' and `princ' that handles circular structures.
+ ;; If OBJECT appears multiply, and has not yet been printed,
+ ;; prefix with label; if it has been printed, use `#N#' instead.
+ ;; Otherwise, print normally.
+ (let ((tag (assq object circle-table)))
+ (if tag
+ (let ((id (cdr tag)))
+ (if (> id 0)
+ (progn
+ ;; Already printed, so just print id.
+ (cust-print-original-princ "#")
+ (cust-print-original-princ id)
+ (cust-print-original-princ "#"))
+ ;; Not printed yet, so label with id and print object.
+ (setcdr tag (- id)) ; mark it as printed
+ (cust-print-original-princ "#")
+ (cust-print-original-princ (- id))
+ (cust-print-original-princ "=")
+ (cust-print-low-level-prin object)
+ ))
+ ;; Not repeated in structure.
+ (cust-print-low-level-prin object))))
+
+
+;;================================================
+;; List and vector processing for print functions.
+
+(defun cust-print-list (list)
+ ;; Print a list using print-length, print-level, and print-circle.
+ (if (= cust-print-current-level 0)
+ (cust-print-original-princ "#")
+ (let ((cust-print-current-level (1- cust-print-current-level)))
+ (cust-print-original-princ "(")
+ (let ((length (or print-length 0)))
+
+ ;; Print the first element always (even if length = 0).
+ (cust-print-prin (car list))
+ (setq list (cdr list))
+ (if list (cust-print-original-princ " "))
+ (setq length (1- length))
+
+ ;; Print the rest of the elements.
+ (while (and list (/= 0 length))
+ (if (and (listp list)
+ (not (assq list circle-table)))
+ (progn
+ (cust-print-prin (car list))
+ (setq list (cdr list)))
+
+ ;; cdr is not a list, or it is in circle-table.
+ (cust-print-original-princ ". ")
+ (cust-print-prin list)
+ (setq list nil))
+
+ (setq length (1- length))
+ (if list (cust-print-original-princ " ")))
+
+ (if (and list (= length 0)) (cust-print-original-princ "..."))
+ (cust-print-original-princ ")"))))
+ list)
+
+
+(defun cust-print-vector (vector)
+ ;; Print a vector according to print-length, print-level, and print-circle.
+ (if (= cust-print-current-level 0)
+ (cust-print-original-princ "#")
+ (let ((cust-print-current-level (1- cust-print-current-level))
+ (i 0)
+ (len (length vector)))
+ (cust-print-original-princ "[")
+
+ (if print-length
+ (setq len (min print-length len)))
+ ;; Print the elements
+ (while (< i len)
+ (cust-print-prin (aref vector i))
+ (setq i (1+ i))
+ (if (< i (length vector)) (cust-print-original-princ " ")))
+
+ (if (< i (length vector)) (cust-print-original-princ "..."))
+ (cust-print-original-princ "]")
+ ))
+ vector)
+
+
+\f
+;; Circular structure preprocessing
+;;==================================
+
+(defun cust-print-preprocess-circle-tree (object)
+ ;; Fill up the table.
+ (let (;; Table of tags for each object in an object to be printed.
+ ;; A tag is of the form:
+ ;; ( <object> <nil-t-or-id-number> )
+ ;; The id-number is generated after the entire table has been computed.
+ ;; During walk through, the real circle-table lives in the cdr so we
+ ;; can use setcdr to add new elements instead of having to setq the
+ ;; variable sometimes (poor man's locf).
+ (circle-table (list nil)))
+ (cust-print-walk-circle-tree object)
+
+ ;; Reverse table so it is in the order that the objects will be printed.
+ ;; This pass could be avoided if we always added to the end of the
+ ;; table with setcdr in walk-circle-tree.
+ (setcdr circle-table (nreverse (cdr circle-table)))
+
+ ;; Walk through the table, assigning id-numbers to those
+ ;; objects which will be printed using #N= syntax. Delete those
+ ;; objects which will be printed only once (to speed up assq later).
+ (let ((rest circle-table)
+ (id -1))
+ (while (cdr rest)
+ (let ((tag (car (cdr rest))))
+ (cond ((cdr tag)
+ (setcdr tag id)
+ (setq id (1- id))
+ (setq rest (cdr rest)))
+ ;; Else delete this object.
+ (t (setcdr rest (cdr (cdr rest))))))
+ ))
+ ;; Drop the car.
+ (cdr circle-table)
+ ))
+
+
+
+(defun cust-print-walk-circle-tree (object)
+ (let (read-equivalent-p tag)
+ (while object
+ (setq read-equivalent-p
+ (or (numberp object)
+ (and (symbolp object)
+ ;; Check if it is uninterned.
+ (eq object (intern-soft (symbol-name object)))))
+ tag (and (not read-equivalent-p)
+ (assq object (cdr circle-table))))
+ (cond (tag
+ ;; Seen this object already, so note that.
+ (setcdr tag t))
+
+ ((not read-equivalent-p)
+ ;; Add a tag for this object.
+ (setcdr circle-table
+ (cons (list object)
+ (cdr circle-table)))))
+ (setq object
+ (cond
+ (tag ;; No need to descend since we have already.
+ nil)
+
+ ((consp object)
+ ;; Walk the car of the list recursively.
+ (cust-print-walk-circle-tree (car object))
+ ;; But walk the cdr with the above while loop
+ ;; to avoid problems with max-lisp-eval-depth.
+ ;; And it should be faster than recursion.
+ (cdr object))
+
+ ((vectorp object)
+ ;; Walk the vector.
+ (let ((i (length object))
+ (j 0))
+ (while (< j i)
+ (cust-print-walk-circle-tree (aref object j))
+ (setq j (1+ j))))))))))
+
+\f
+;; Example.
+;;=======================================
+
+'(progn
+ (progn
+ ;; Create some circular structures.
+ (setq circ-sym (let ((x (make-symbol "FOO"))) (list x x)))
+ (setq circ-list (list 'a 'b (vector 1 2 3 4) 'd 'e 'f))
+ (setcar (nthcdr 3 circ-list) circ-list)
+ (aset (nth 2 circ-list) 2 circ-list)
+ (setq dotted-circ-list (list 'a 'b 'c))
+ (setcdr (cdr (cdr dotted-circ-list)) dotted-circ-list)
+ (setq circ-vector (vector 1 2 3 4 (list 'a 'b 'c 'd) 6 7))
+ (aset circ-vector 5 (make-symbol "-gensym-"))
+ (setcar (cdr (aref circ-vector 4)) (aref circ-vector 5))
+ nil)
+
+ (install-custom-print)
+ ;; (setq print-circle t)
+
+ (let ((print-circle t))
+ (or (equal (prin1-to-string circ-list) "#1=(a b [1 2 #1# 4] #1# e f)")
+ (error "circular object with array printing")))
+
+ (let ((print-circle t))
+ (or (equal (prin1-to-string dotted-circ-list) "#1=(a b c . #1#)")
+ (error "circular object with array printing")))
+
+ (let* ((print-circle t)
+ (x (list 'p 'q))
+ (y (list (list 'a 'b) x 'foo x)))
+ (setcdr (cdr (cdr (cdr y))) (cdr y))
+ (or (equal (prin1-to-string y) "((a b) . #1=(#2=(p q) foo #2# . #1#))"
+ )
+ (error "circular list example from CL manual")))
+
+ (let ((print-circle nil))
+ ;; cl-packages.el is required to print uninterned symbols like #:FOO.
+ ;; (require 'cl-packages)
+ (or (equal (prin1-to-string circ-sym) "(#:FOO #:FOO)")
+ (error "uninterned symbols in list")))
+ (let ((print-circle t))
+ (or (equal (prin1-to-string circ-sym) "(#1=FOO #1#)")
+ (error "circular uninterned symbols in list")))
+
+ (uninstall-custom-print)
+ )
+
+(provide 'cust-print)
+
+;;; arch-tag: 3a5a8650-622c-48c4-87d8-e01bf72ec580
+;;; cust-print.el ends here
HCoop / bpt / emacs.git / blobdiff