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authorKarl Berry <karl@freefriends.org>2010-09-24 00:06:55 +0000
committerKarl Berry <karl@freefriends.org>2010-09-24 00:06:55 +0000
commit41d4e60fba44409eb9361200ff517a6bf67936c6 (patch)
treec2feeef423a6f27a89cdc9816fd354a2f59187be /Master/texmf-dist/tex/generic/path
parented89e18f4912e0485a4cd0cd3553a12658a32701 (diff)
now in generic (23sep10)
git-svn-id: svn://tug.org/texlive/trunk@19866 c570f23f-e606-0410-a88d-b1316a301751
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+%%% @LaTeX-style-file
+%%% {
+%%% author = "Philip Taylor",
+%%% version = "3.03b",
+%%% date = "22 July 1997",
+%%% time = "15:59:31 BST",
+%%% filename = "path.sty",
+%%% address = "The Computer Centre
+%%% RHBNC, University of London
+%%% Egham Hill
+%%% Egham, Surrey TW20 0EX, ENGLAND",
+%%% telephone = "Tel: +44 1784 443172",
+%%% FAX = "Fax: +44 1784 434348",
+%%% email = "P.Taylor@Vms.Rhbnc.Ac.Uk",
+%%% codetable = "ISO/ASCII",
+%%% keywords = "file name, filename, path name, pathname,
+%%% discretionary, discretionaries",
+%%% supported = "yes",
+%%% docstring = {Computer filenames, host names, and e-mail
+%%% addresses tend to be long strings that
+%%% cause line breaking problems for TeX.
+%%% Sometimes rather long strings are
+%%% encountered, such as:
+%%%
+%%% mighty-mouse-gw.scrc.symbolics.com
+%%%
+%%% This file defines a macro, \path|...|,
+%%% similar to LaTeX's \verb|...| macro, that
+%%% sets the text in the typewriter font,
+%%% allowing hyphen-less line breaks at
+%%% punctuation characters.
+%%%
+%%% The default set of punctuation characters is
+%%% defined as
+%%%
+%%% \discretionaries |~!@$%^&*()_+`-=#{"}[]:;'<>,.?\/|
+%%%
+%%% However, you can change it as needed, for
+%%% example
+%%%
+%%% \discretionaries +@%!.+
+%%%
+%%% would assign to it the set @ % ! . which
+%%% commonly occur in electronic mail addresses.
+%%%
+%%% The delimiter characters surrounding the
+%%% arguments to \discretionaries and \path
+%%% will normally be a punctuation character not
+%%% found in the argument, and not otherwise
+%%% significant to TeX. In particular, backslash
+%%% cannot be used as a delimiter. In the rare
+%%% event that this is required, set
+%%%
+%%% \specialpathdelimiterstrue
+%%%
+%%% This practice is not recommended, because TeX
+%%% then runs about four times slower while it is
+%%% typesetting \path\...\ requests.
+%%% \specialpathdelimitersfalse is the normal
+%%% setting.
+%%%
+%%% This file may be used in Plain TeX or AmSTeX
+%%% by
+%%%
+%%% \input path.sty
+%%%
+%%% and in LaTeX by
+%%%
+%%% \usepackage {path}
+%%%
+%%% The checksum field above, if present, contains
+%%% a CRC-16 checksum as the first value, followed
+%%% by the equivalent of the standard UNIX wc (word
+%%% count) utility output of lines, words, and
+%%% characters. This is produced by Robert
+%%% Solovay's checksum utility.
+%%% }
+%%% }
+%%% ====================================================================
+
+% ======================================================================
+%
+% The \path Macro
+%
+% An early prototype of this code which was developed by Nelson H. F.
+% Beebe <beebe@math.utah.edu> used a recursive macro to peel off one
+% character at a time, then with a nest of \ifx statements, test for
+% each punctuation character, and if one is found, insert discretionary
+% linebreaks in the form of \- or \penalty0. While this usually works,
+% it is not entirely satisfactory, because the nested \ifx statements
+% are ugly, and the recursion can exhaust TeX's macro stack for
+% arguments longer than about 30 characters.
+%
+% A second version by NHFB built upon the ideas used by the LaTeX
+% \verb|...| macro; this was mostly successful, but was flawed by its
+% inability to handle at least the three characters ^ [ ], by loss of
+% use of @ for naming internal private macros, and by its inability to
+% allow the set of characters at which breaks are permissible.
+%
+% The problem was then passed off to Philip Taylor, who wrote this third
+% version which fully solves the problem. Phil therefore gets the
+% author credit in the file header above. [Gee, thanks ! ** Phil]
+%
+% Revision history (reverse time order):
+%
+% 3.03b [22-Jul-1997]
+% Summary: No code changes. An out-of-date example removed, the syntax
+% for LaTeX2e changed to "\usepackage {path}", and the "checksum"
+% comments modified to indicate that the checksum is not necessarily
+% present. The initial opening brace re-positioned to align
+% with the matching closing brace, and the inner closing brace
+% re-positioned to align with the inner opening brace. A check made
+% to ensure that no <tab> characters are present.
+%
+% 3.03a [22-Jul-1997]
+% Summary: No code changes from V3.03; e-mail addresses, telephone numbers,
+% etc. amended to reflect current situation. Checksum removed.
+%
+% 3.03 [03-Dec-1991]
+% Problem: A \path|...| entry in a LaTeX index is set with an
+% preceding blank line.
+% Solution: Add \leavevmode before \hbox{}; without it, an extra blank
+% line gets typeset before every invocation of \path in a
+% LaTeX theindex environment.
+% Diagnosis: To avoid hyphenation, the expansion of \path starts with
+% an \hbox{} (c.f. the TeXbook, p. 454); LaTeX indices are
+% basically set in vertical mode, with each index entry a
+% paragraph in its own right; when an \hbox {} is
+% encountered in vmode, it is typeset in vmode, and TeX
+% continues; the first real character is encountered, and
+% TeX enters unrestricted horizontal mode. The \hbox {} and
+% the first character are therefore on separate lines,
+% separated by \baselineskip.
+%
+% 3.02 [23-Oct-1991 13:45:12]
+% First released version.
+% ======================================================================
+
+\immediate\write16{This is path.sty, Version 3.03 <03-Dec-1991>}
+
+%%% We will regrettably need one \count variable with an open name,
+%%% in which to save the category code of commercial-at ...
+
+\newcount \ATcode
+\ATcode = \catcode `\@
+
+%%% Make commercial-at a letter to provide concealed control sequences
+
+\catcode `\@ = 11
+
+%%% and then declare two \count variables with concealed names
+
+\newcount \c@tcode
+\newcount \c@unter
+
+%%% and a boolean variable with an open name, to specify the nature of
+%%% the delimiters which will be associated with the \path command
+
+\newif \ifspecialpathdelimiters
+
+%%% We need to define control sequences which expand to both
+%%% active and passive spaces ...
+
+\begingroup
+\catcode `\ = 10
+\gdef \passivesp@ce { }
+\catcode `\ = 13\relax%
+\gdef\activesp@ce{ }%
+\endgroup
+
+%%% \discretionaries will define a macro \discr@ti@n@ri@s which will
+%%% make every character between the first and final <delim> a
+%%% discretionary breakpoint.
+
+\def \discretionaries %%% <delim> <chars> <delim>
+ % start a group (ended in \discr@ti@naries ),
+ % make every character (apart from space) active,
+ % then transfer control to \discr@tionaries ...
+ {\begingroup
+ \c@tcodes = 13
+ \discr@tionaries
+ }
+
+%%% \discr@tionaries will receive as parameter the initial <delim>
+%%% which will delimit the set of discretionaries; this <delim>
+%%% will be active.
+
+\def \discr@tionaries #1%%% <delim>
+ % knowing the initial <delim>, define \discr@ti@naries with a
+ % delimited parameter structure, the final delimiter being
+ % the second instance of <delim>
+ {\def \discr@ti@naries ##1#1%%% <chars> <delim>
+ % \discr@ti@naries will receive as parameter the set of
+ % characters which are to be made discretionaries; it ends the
+ % group and then defines \discr@ti@n@ries, a tail-recursive
+ % macro, which will quietly process each of the
+ % discretionaries in turn ...
+ {\endgroup
+ \def \discr@ti@n@ries ####1%%% <char> or <delim>
+ % by checking to see if it has reached the end of the
+ % list, i.e. comparing its parameter with the known final
+ % <delim> ...
+ {\if \noexpand ####1\noexpand #1%
+ % if they match, there is no more to do ...
+ \let \n@xt = \relax
+ \else
+ % otherwise the character becomes active and is
+ % defined as a discretionary with the three texts
+ % <self> <empty> <self>, thus suppressing true
+ % hyphenation; the macro then prepares to process
+ % the next character.
+ \catcode `####1 = 13
+ \def ####1{\discretionary
+ {\char `####1}{}{\char `####1}}%
+ \let \n@xt = \discr@ti@n@ries
+ \fi
+ % here either tail recursion occurs, if there are more
+ % characters to process, or tail recursion ceases if all
+ % have been exhausted
+ \n@xt
+ }%
+ % of course, none of this must take place during the \stress
+ % {call} of \discretionaries; execution is deferred until
+ % another macro such as \path calls the concealed action
+ % macro \discr@ti@n@ri@s; we therefore define this macro to
+ % have the desired effect.
+ \def \discr@ti@n@ri@s {\discr@ti@n@ries ##1#1}%
+ }%
+ % and finally invoke \discr@ti@naries to process the set of
+ % discretionary characters; it will take everything up to the
+ % second instance of <delim> as its parameter (and therefore as the
+ % set of characters to be processed).
+ \discr@ti@naries
+ }
+
+%%% \path, which is the user interface to \p@th, first checks
+%%% to see whether \specialpathdelimiters is <true> or <false>;
+%%% if <true>, it needs to take special action to ensure that
+%%% \stress {all} characters (apart from <space>) are acceptable
+%%% as delimiters; this is very time-consuming, and should be
+%%% avoided if at all possible. It also defines \endp@th, to
+%%% close the appropriate number of groups, and finally transfers
+%%% control to \p@th
+
+\def \path
+ {\ifspecialpathdelimiters
+ \begingroup
+ \c@tcodes = 12
+ \def \endp@th {\endgroup \endgroup}%
+ \else
+ \let \endp@th = \endgroup
+ \fi
+ \p@th
+ }
+
+%%% \p@th, which has essentially the same syntax as \discretionaries,
+%%% expects to be followed by a <delim>, a <path>, and a second instance
+%%% of <delim>; it will typeset <path> in the \tt font with hyphenation
+%%% inhibited --- breaks (but not true hyphenation) are allowed at any
+%%% or all of the special characters which have
+%%% previously been declared as \discretionaries.
+
+\def \p@th #1%%% <delim>
+ % it starts by opening a group (ended in \p@@th) ...
+ % switches to \tt, and inhibits hyphenation;
+ % allows breaks at \discretionaries; saves the
+ % catcode of the initial <delim>, because if it has also been
+ % declared within \discretionaries, the initial and final <delim>
+ % won't match (which would be a disaster); \c@tcode is overloaded,
+ % but there is no conflict that I can detect ...
+ % invokes \discr@ti@n@ri@s to render active the set of special
+ % characters which have previously been declared as
+ % \discretionaries; each of these characters will expand to a real
+ % \discretionary, with replacement texts <self> <null> <self>; and
+ % re-instates the catcode of the initial <delim>.
+ {\begingroup
+ \tt
+ \c@tcode = \catcode `#1
+ \discr@ti@n@ri@s
+ \catcode `\ = \active
+ \expandafter \edef \activesp@ce {\passivesp@ce \hbox {}}%
+ \catcode `#1 = \c@tcode
+ % it next defines an inner macro \p@@th with delimited parameter
+ % structure, the final delimiter being the same as the initial
+ % delimiter which it has itself received as #1.
+ \def \p@@th ##1#1% <chars> <delim>
+ % Within \p@@th,
+ % permissible breakpoints are specified,
+ % the path is typeset,
+ % and the group(s) ended.
+ {\leavevmode \hbox {}##1%
+ \endp@th
+ }%
+ \p@@th
+ }
+
+%%% \c@tcodes expects to be followed by the r-h-s of a numeric
+%%% assignment optionally including the assignment operator; it saves
+%%% the value of the r-h-s in \c@tcode, and invokes \c@tc@des.
+
+\def \c@tcodes {\afterassignment \c@tc@des \c@tcode}
+
+%%% \c@tc@des uses the value saved in \c@tcode, and assigns it to the
+%%% \catcode of all characters with the single exception of <space>,
+%%% which retains its normal catcode of 10; on exit, every single
+%%% character apart from <space> will have the catcode which followed
+%%% \c@tcodes. The code is optimised to avoid unnecessary usage of
+%%% save-stack space.
+
+\def \c@tc@des
+ {\c@unter = 0
+ \loop
+ \ifnum \catcode \c@unter = \c@tcode
+ \else
+ \catcode \c@unter = \c@tcode
+ \fi
+ \ifnum \c@unter < 255
+ \advance \c@unter by 1
+ \repeat
+ \catcode `\ = 10
+ }
+
+%%% We restore the original catcode of commercial-at
+
+\catcode `\@ = \ATcode
+
+%%% Define a default set of discretionary break characters
+%%% to include all punctuation characters except vertical
+%%% bar
+
+\discretionaries |~!@$%^&*()_+`-=#{}[]:";'<>,.?\/|
+
+\endinput