+++ /dev/null
-;;; cust-print.el --- handles print-level and print-circle
-
-;; Copyright (C) 1992, 2001-2012 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 3 of the License, 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. If not, see <http://www.gnu.org/licenses/>.
-
-;;; 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'."
- :type 'boolean
- :group 'cust-print)
-
-\f
-;; Custom printers
-;;==========================================================
-
-(defvar 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))
- (mapc '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)
- (mapc '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)
- (mapc '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.
- (with-current-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))
- (with-current-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)
-
-;;; cust-print.el ends here
HCoop / bpt / emacs.git / blobdiff