%%% @texfile{ %%% author = "Philip Taylor", %%% version = "3.04", %%% date = "25 July 1992", %%% time = "17:07 EDT", %%% filename = "path.sty", %%% address = "The Computer Centre %%% RHBNC, University of London %%% Egham Hill %%% Egham, Surrey TW20 0EX, ENGLAND", %%% telephone = "Tel: +44 784 443172", %%% FAX = "Fax: +44 784 434348", %%% checksum = "41143 321 1758 13526", %%% email = "P.Taylor@Vax.Rhbnc.Ac.Uk (Internet)", %%% 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; here are two examples: %%% %%% Friesland%rz.informatik.uni-hamburg.dbp.de%germany.csnet@relay.cs.net %%% %%% 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 %%% %%% \documentstyle[...,path,...]{...} %%% %%% The checksum field above 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.} %%% } % % ====================================================================== % % History of the \path macro % % An early prototype of this code which was developed by Nelson H. F. % Beebe 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] % % Then Karl Berry made minor changes in July 1992. % % Revision history (reverse time order): % % 3.04 [22-Jul-1992] % (changes by karl@cs.umb.edu, with Phil's blessing): % 1) use \edef to avoid wasting a count register merely to save the % catcode of @. % % 2) Expand a macro \pathafterhook (if it's defined) once \path is % entirely finished, for the benefit of macros using \path. % % 3) % all blank lines and post-}'s, in the (highly unusual) case that % the file is being read in horizontal mode. Use only one %, not % three, so the comments can be easily removed automatically. % % 4) Remove the \endinput from the end of the file. What does it add? % % % 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{path.sty version 3.04 <25 Jul 1992>}% % % The use of `\path' as a temporary control sequence is a kludge, but % it's a reasonably simple way to accomplish making @ a letter (to % provide ``concealed'' control sequences) without overwriting something % (without an `@' in its name) that might already be defined. % \edef\path{\the\catcode`@}% \catcode`@ = 11 \let\@oldatcatcode = \path % % % 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 a % discretionary breakpoint. % \def \discretionaries % % 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 % which will delimit the set of discretionaries; this % will be active. % \def \discr@tionaries #1% % knowing the initial , define \discr@ti@naries with a % delimited parameter structure, the final delimiter being % the second instance of {\def \discr@ti@naries ##1#1% % \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% or % by checking to see if it has reached the end of the % list, i.e. comparing its parameter with the known final % ... {\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 % , 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 as its parameter (and therefore as the % set of characters to be processed). \discr@ti@naries }% % % % If desired, you can define \pathafterhook to be anything. % \let\pathafterhook = \relax % % % \path, which is the user interface to \p@th, first checks to see % whether \specialpathdelimiters is or ; if , it % needs to take special action to ensure that \stress {all} characters % (apart from ) 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 \pathafterhook}% \else \def \endp@th {\endgroup \pathafterhook}% \fi \p@th }% % % % \p@th, which has essentially the same syntax as \discretionaries, % expects to be followed by a , a , and a second instance % of ; it will typeset 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% % 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 , because if it has also been % declared within \discretionaries, the initial and final % 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 ; and % re-instates the catcode of the initial . {\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% % 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 , which % retains its normal catcode of 10; on exit, every single character % apart from 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 }% % % % Restore the original catcode of commercial-at. \catcode `\@ = \@oldatcatcode % % % Define a default set of discretionary break characters to include all % punctuation characters except vertical bar. % \discretionaries |~!@$%^&*()_+`-=#{}[]:";'<>,.?\/|%