cl-ppcre/util.lisp

;;; -*- Mode: LISP; Syntax: COMMON-LISP; Package: CL-PPCRE; Base: 10 -*-
;;; $Header: /usr/local/cvsrep/cl-ppcre/util.lisp,v 1.40 2008/07/03 10:06:16 edi Exp $

;;; Utility functions and constants dealing with the character sets we
;;; use to encode character classes

;;; Copyright (c) 2002-2008, Dr. Edmund Weitz. All rights reserved.

;;; Redistribution and use in source and binary forms, with or without
;;; modification, are permitted provided that the following conditions
;;; are met:

;;;   * Redistributions of source code must retain the above copyright
;;;     notice, this list of conditions and the following disclaimer.

;;;   * Redistributions in binary form must reproduce the above
;;;     copyright notice, this list of conditions and the following
;;;     disclaimer in the documentation and/or other materials
;;;     provided with the distribution.

;;; THIS SOFTWARE IS PROVIDED BY THE AUTHOR 'AS IS' AND ANY EXPRESSED
;;; OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
;;; WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
;;; ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
;;; DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
;;; DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
;;; GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
;;; INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
;;; WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
;;; NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
;;; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

(in-package #:cl-ppcre)

#+:lispworks
(eval-when (:compile-toplevel :load-toplevel :execute)
  (import 'lw:with-unique-names))

#-:lispworks
(defmacro with-unique-names ((&rest bindings) &body body)
  "Syntax: WITH-UNIQUE-NAMES ( { var | (var x) }* ) declaration* form*

Executes a series of forms with each VAR bound to a fresh,
uninterned symbol. The uninterned symbol is as if returned by a call
to GENSYM with the string denoted by X - or, if X is not supplied, the
string denoted by VAR - as argument.

The variable bindings created are lexical unless special declarations
are specified. The scopes of the name bindings and declarations do not
include the Xs.

The forms are evaluated in order, and the values of all but the last
are discarded \(that is, the body is an implicit PROGN)."
  ;; reference implementation posted to comp.lang.lisp as
  ;; <cy3bshuf30f.fsf@ljosa.com> by Vebjorn Ljosa - see also
  ;; <http://www.cliki.net/Common%20Lisp%20Utilities>
  `(let ,(mapcar #'(lambda (binding)
                     (check-type binding (or cons symbol))
                     (if (consp binding)
                       (destructuring-bind (var x) binding
                         (check-type var symbol)
                         `(,var (gensym ,(etypecase x
                                          (symbol (symbol-name x))
                                          (character (string x))
                                          (string x)))))
                       `(,binding (gensym ,(symbol-name binding)))))
                 bindings)
         ,@body))

#+:lispworks
(eval-when (:compile-toplevel :load-toplevel :execute)
  (setf (macro-function 'with-rebinding)
          (macro-function 'lw:rebinding)))

#-:lispworks
(defmacro with-rebinding (bindings &body body)
  "WITH-REBINDING ( { var | (var prefix) }* ) form*

Evaluates a series of forms in the lexical environment that is
formed by adding the binding of each VAR to a fresh, uninterned
symbol, and the binding of that fresh, uninterned symbol to VAR's
original value, i.e., its value in the current lexical environment.

The uninterned symbol is created as if by a call to GENSYM with the
string denoted by PREFIX - or, if PREFIX is not supplied, the string
denoted by VAR - as argument.

The forms are evaluated in order, and the values of all but the last
are discarded \(that is, the body is an implicit PROGN)."
  ;; reference implementation posted to comp.lang.lisp as
  ;; <cy3wv0fya0p.fsf@ljosa.com> by Vebjorn Ljosa - see also
  ;; <http://www.cliki.net/Common%20Lisp%20Utilities>
  (loop for binding in bindings
        for var = (if (consp binding) (car binding) binding)
        for name = (gensym)
        collect `(,name ,var) into renames
        collect ``(,,var ,,name) into temps
        finally (return `(let ,renames
                          (with-unique-names ,bindings
                            `(let (,,@temps)
                              ,,@body))))))

(eval-when (:compile-toplevel :execute :load-toplevel)
  (defun make-char-set (test)
    (declare #.*special-optimize-settings*)
    "Returns a CHARSET for all characters satisfying test."
    (loop with set = (make-charset)
          for code of-type fixnum from 0 below char-code-limit
          for char = (code-char code)
          if (and char (funcall test char))
          do (add-to-charset char set)
          finally (return set)))

  (declaim (inline word-char-p))
  
  (defun word-char-p (chr)
    (declare #.*standard-optimize-settings*)
    "Tests whether a character is a \"word\" character.
In the ASCII charset this is equivalent to a-z, A-Z, 0-9, or _,
i.e. the same as Perl's [\\w]."
    (or (alphanumericp chr)
        (char= chr #\_)))

  (unless (boundp '+whitespace-char-string+)
    (defconstant +whitespace-char-string+
      (coerce
       '(#\Space #\Tab #\Linefeed #\Return #\Page)
       'string)
      "A string of all characters which are considered to be whitespace.
Same as Perl's [\\s]."))

  (defun whitespacep (chr)
    (declare #.*special-optimize-settings*)
    "Tests whether a character is whitespace,
i.e. whether it would match [\\s] in Perl."
    (find chr +whitespace-char-string+ :test #'char=)))

;; the following DEFCONSTANT statements are wrapped with
;; (UNLESS (BOUNDP ...) ...) to make SBCL happy

(unless (boundp '+digit-set+)
  (defconstant +digit-set+
    (make-char-set (lambda (chr) (char<= #\0 chr #\9)))
    "Character set containing the digits from 0 to 9."))

(unless (boundp '+word-char-set+)
  (defconstant +word-char-set+
    (make-char-set #'word-char-p)
    "Character set containing all \"word\" characters."))

(unless (boundp '+whitespace-char-set+)
  (defconstant +whitespace-char-set+
    (make-char-set #'whitespacep)
    "Character set containing all whitespace characters."))

(defun create-ranges-from-set (set &key downcasep)
  (declare #.*standard-optimize-settings*)
  "Tries to identify up to three intervals \(with respect to CHAR<)
which together comprise the charset SET.  Returns NIL if this is not
possible.  If DOWNCASEP is true it will treat the charset as if it
represents both the lower-case and the upper-case variants of its
members and will only return the respective lower-case intervals."
  ;; discard empty charsets
  (unless (and set (plusp (charset-count set)))
    (return-from create-ranges-from-set nil))
  (loop with min1 and min2 and min3
        and max1 and max2 and max3
        ;; loop through all characters in SET, sorted by CHAR<
        ;; (actually by < on their character codes, see 13.1.6 in the
        ;; ANSI standard)
        for code of-type fixnum below *regex-char-code-limit*
        for char = (code-char code)
        when (and char (in-charset-p (if downcasep (char-downcase char) char) set))
        ;; MIN1, MAX1, etc. are _exclusive_
        ;; bounds of the intervals identified so far
        do (cond
            ((not min1)
             ;; this will only happen once, for the first character
             (setq min1 (1- code)
                   max1 (1+ code)))
            ((<= (the fixnum min1) code (the fixnum max1))
             ;; we're here as long as CHAR fits into the first interval
             (setq min1 (min (the fixnum min1) (1- code))
                   max1 (max (the fixnum max1) (1+ code))))
            ((not min2)
             ;; we need to open a second interval
             ;; this'll also happen only once
             (setq min2 (1- code)
                   max2 (1+ code)))
            ((<= (the fixnum min2) code (the fixnum max2))
             ;; CHAR fits into the second interval
             (setq min2 (min (the fixnum min2) (1- code))
                   max2 (max (the fixnum max2) (1+ code))))
            ((not min3)
             ;; we need to open the third interval
             ;; happens only once
             (setq min3 (1- code)
                   max3 (1+ code)))
            ((<= (the fixnum min3) code (the fixnum max3))
             ;; CHAR fits into the third interval
             (setq min3 (min (the fixnum min3) (1- code))
                   max3 (max (the fixnum max3) (1+ code))))
            (t
             ;; we're out of luck, CHAR doesn't fit
             ;; into one of the three intervals
             (return nil)))
        ;; on success return all bounds
        ;; make them inclusive bounds before returning
        finally (return (values (code-char (1+ min1))
                                (code-char (1- max1))
                                (and min2 (code-char (1+ min2)))
                                (and max2 (code-char (1- max2)))
                                (and min3 (code-char (1+ min3)))
                                (and max3 (code-char (1- max3)))))))

(defmacro maybe-coerce-to-simple-string (string)
  (with-unique-names (=string=)
    `(let ((,=string= ,string))
      (cond ((simple-string-p ,=string=)
              ,=string=)
            (t
              (coerce ,=string= 'simple-string))))))

(declaim (inline nsubseq))
(defun nsubseq (sequence start &optional (end (length sequence)))
  "Return a subsequence by pointing to location in original sequence."
  (make-array (- end start)
              :element-type (array-element-type sequence)
              :displaced-to sequence
              :displaced-index-offset start))

(defun normalize-var-list (var-list)
  "Utility function for REGISTER-GROUPS-BIND and
DO-REGISTER-GROUPS. Creates the long form \(a list of \(FUNCTION VAR)
entries) out of the short form of VAR-LIST."
  (loop for element in var-list
        if (consp element)
          nconc (loop for var in (rest element)
                      collect (list (first element) var))
        else
          collect (list '(function identity) element)))

(defun string-list-to-simple-string (string-list)
  (declare #.*standard-optimize-settings*)
  "Concatenates a list of strings to one simple-string."
  ;; this function provided by JP Massar; note that we can't use APPLY
  ;; with CONCATENATE here because of CALL-ARGUMENTS-LIMIT
  (let ((total-size 0))
    (declare (type fixnum total-size))
    (dolist (string string-list)
      #-genera (declare (type string string))
      (incf total-size (length string)))
    (let ((result-string (make-sequence 'simple-string total-size))
          (curr-pos 0))
      (declare (type fixnum curr-pos))
      (dolist (string string-list)
        #-genera (declare (type string string))
        (replace result-string string :start1 curr-pos)
        (incf curr-pos (length string)))
      result-string)))