src/code/early-print.lisp

   1 ;;;; printer stuff which has to be defined early (e.g. DEFMACROs)
   2
   3 ;;;; This software is part of the SBCL system. See the README file for
   4 ;;;; more information.
   5 ;;;;
   6 ;;;; This software is derived from the CMU CL system, which was
   7 ;;;; written at Carnegie Mellon University and released into the
   8 ;;;; public domain. The software is in the public domain and is
   9 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
  10 ;;;; files for more information.
  11
  12 (in-package "SB!IMPL")
  13 \f
  14 ;;;; level and length abbreviations
  15
  16 ;;; The current level we are printing at, to be compared against
  17 ;;; *PRINT-LEVEL*. See the macro DESCEND-INTO for a handy interface to
  18 ;;; depth abbreviation.
  19 (defvar *current-level-in-print* 0)
  20
  21 ;;; Automatically handle *PRINT-LEVEL* abbreviation. If we are too
  22 ;;; deep, then a #\# is printed to STREAM and BODY is ignored.
  23 (defmacro descend-into ((stream) &body body)
  24   (let ((flet-name (gensym)))
  25     `(flet ((,flet-name ()
  26               ,@body))
  27        (cond ((and (null *print-readably*)
  28                    *print-level*
  29                    (>= *current-level-in-print* *print-level*))
  30               (write-char #\# ,stream))
  31              (t
  32               (let ((*current-level-in-print* (1+ *current-level-in-print*)))
  33                 (,flet-name)))))))
  34
  35 ;;; Punt if INDEX is equal or larger then *PRINT-LENGTH* (and
  36 ;;; *PRINT-READABLY* is NIL) by outputting \"...\" and returning from
  37 ;;; the block named NIL.
  38 (defmacro punt-print-if-too-long (index stream)
  39   `(when (and (not *print-readably*)
  40               *print-length*
  41               (>= ,index *print-length*))
  42      (write-string "..." ,stream)
  43      (return)))