src/code/readtable.lisp

   1 ;;;; READTABLEs
   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
  14 (sb!xc:deftype attribute-table ()
  15   '(simple-array (unsigned-byte 8) (#.base-char-code-limit)))
  16
  17 ;;; constants for readtable character attributes. These are all as in
  18 ;;; the manual.
  19 ;;;
  20 ;;; FIXME: wait a minute.  Firstly, I doubt they're in the manual.
  21 ;;; Secondly, the numerical order of these constants is coupled with
  22 ;;; code in CHAR-CLASS{,2,3} in the reader implementation, so beware
  23 ;;; when changing them.
  24 (def!constant +char-attr-whitespace+ 0)
  25 (def!constant +char-attr-terminating-macro+ 1)
  26 (def!constant +char-attr-single-escape+ 2)
  27 (def!constant +char-attr-multiple-escape+ 3)
  28 (def!constant +char-attr-constituent+ 4)
  29 (def!constant +char-attr-constituent-dot+ 5)
  30 (def!constant +char-attr-constituent-expt+ 6)
  31 (def!constant +char-attr-constituent-slash+ 7)
  32 (def!constant +char-attr-constituent-digit+ 8)
  33 (def!constant +char-attr-constituent-sign+ 9)
  34 ;;; the following two are not static but depend on *READ-BASE*.
  35 ;;; DECIMAL-DIGIT is for characters being digits in base 10 but not in
  36 ;;; base *READ-BASE* (which is therefore perforce smaller than 10);
  37 ;;; DIGIT-OR-EXPT is for characters being both exponent markers and
  38 ;;; digits in base *READ-BASE* (which is therefore perforce larger
  39 ;;; than 10).  -- CSR, 2004-03-16
  40 (def!constant +char-attr-constituent-decimal-digit+ 10)
  41 (def!constant +char-attr-constituent-digit-or-expt+ 11)
  42
  43 (def!constant +char-attr-package-delimiter+ 12)
  44 (def!constant +char-attr-invalid+ 13)
  45 (def!constant +char-attr-delimiter+ 14) ; (a fake for READ-UNQUALIFIED-TOKEN)
  46
  47 (sb!xc:defstruct (readtable (:conc-name nil)
  48                             (:predicate readtablep)
  49                             ;; ANSI requires a CL:COPY-READTABLE to do
  50                             ;; a deep copy, so the DEFSTRUCT-generated
  51                             ;; default is not suitable.
  52                             (:copier nil))
  53   #!+sb-doc
  54   "A READTABLE is a data structure that maps characters into syntax
  55    types for the Common Lisp expression reader."
  56   ;; The CHARACTER-ATTRIBUTE-TABLE is a vector of CHAR-CODE-LIMIT
  57   ;; integers for describing the character type. Conceptually, there
  58   ;; are 4 distinct "primary" character attributes:
  59   ;; +CHAR-ATTR-WHITESPACE+, +CHAR-ATTR-TERMINATING-MACRO+,
  60   ;; +CHAR-ATTR-ESCAPE+, and +CHAR-ATTR-CONSTITUENT+. Non-terminating
  61   ;; macros (such as the symbol reader) have the attribute
  62   ;; +CHAR-ATTR-CONSTITUENT+.
  63   ;;
  64   ;; In order to make READ-TOKEN fast, all this information is stored
  65   ;; in the character attribute table by having different varieties of
  66   ;; constituents.
  67   (character-attribute-array
  68    (make-array base-char-code-limit
  69                :element-type '(unsigned-byte 8)
  70                :initial-element +char-attr-constituent+)
  71    :type attribute-table)
  72   (character-attribute-hash-table (make-hash-table) :type hash-table)
  73   ;; The CHARACTER-MACRO-TABLE is a vector of CHAR-CODE-LIMIT
  74   ;; functions. One of these functions called with appropriate
  75   ;; arguments whenever any non-WHITESPACE character is encountered
  76   ;; inside READ-PRESERVING-WHITESPACE. These functions are used to
  77   ;; implement user-defined read-macros, system read-macros, and the
  78   ;; number-symbol reader.
  79   (character-macro-array
  80    (make-array base-char-code-limit :initial-element #'undefined-macro-char)
  81    :type (simple-vector #.base-char-code-limit))
  82   (character-macro-hash-table (make-hash-table) :type hash-table)
  83   ;; an alist from dispatch characters to vectors of CHAR-CODE-LIMIT
  84   ;; functions, for use in defining dispatching macros (like #-macro)
  85   (dispatch-tables () :type list)
  86   (readtable-case :upcase :type (member :upcase :downcase :preserve :invert)))