doc-src/url.sty

clarified remark

% url.sty  ver 1.1    6-Feb-1996   Donald Arseneau   [e-mail]
%
% A form of \verb that allows linebreaks at certain characters or 
% combinations of characters, accepts reconfiguration, and can usually
% be used in the argument to another command.  It is intended for email
% addresses, hypertext links, directories/paths, etc., which normally 
% have no spaces.  The font may be selected using the \urlstyle command, 
% and new url-like commands can be defined using \urldef.
%
% Usage:    Conditions:
% \url{ }   If the argument contains any "%", "#", or "^^", or ends with
%           "\", it can't be used in the argument to another command.  
%           The argument must not contain unbalanced braces.
% \url|  |  ...where "|" is any character not used in the argument and not 
%           "{".  The same restrictions as above except that the argument
%           may contain unbalanced braces.
% \xyz      for "\xyz" a defined-url;  this can be used anywhere, no matter
%           what characters it contains.
% 
% See further instructions after "\endinput"

\def\url@ttstyle{%
\@ifundefined{selectfont}{\def\UrlFont{\tt}}{\def\UrlFont{\ttfamily}}% 
\def\UrlBreaks{\do\.\do\@\do\\\do\/\do\!\do\_\do\|\do\%\do\;\do\>\do\]%
 \do\)\do\,\do\?\do\'\do\+\do\=\do@url@hyp}%
\def\UrlBigBreaks{\do\:}%
\def\UrlNoBreaks{\do\(\do\[\do\{\do\<}% (unnecessary)
\def\UrlSpecials{\do\ {\ }}%
\def\UrlOrds{\do\*\do\-}% any ordinary characters that aren't usually
}
\def\url@rmstyle{%
\@ifundefined{selectfont}{\def\UrlFont{\rm}}{\def\UrlFont{\rmfamily}}% 
\def\UrlBreaks{\do\.\do\@\do\/\do\!\do\%\do\;\do\]\do\)\do\,\do\?\do@url@hyp
  \do\+\do\=}%
\def\UrlBigBreaks{\do\:}%
\def\UrlNoBreaks{\do\(\do\[\do\{}% prevents breaks after *next* character
\def\UrlSpecials{\do\<{\langle}\do\>{\rangle\penalty\relpenalty}\do\_{\_%
 \penalty\@m}\do\|{\mid}\do\{{\lbrace}\do\}{\rbrace\penalty\relpenalty}\do
 \\{\mathbin{\backslash}}\do\~{\mathord{{}^{\textstyle\sim}}}\do\ {\ }}%
\def\UrlOrds{\do\'\do\"\do\-}%
}
\def\url@sfstyle{\url@rmstyle 
\@ifundefined{selectfont}{\def\UrlFont{\sf}}{\def\UrlFont{\sffamily}}% 
}
\def\url@samestyle{\ifdim\fontdimen\thr@@\font=\z@ \url@ttstyle \else
  \url@rmstyle \fi \def\UrlFont{}}

\def\do@url@hyp{}% by default, no breaks after hyphens

\@ifundefined{strip@prefix}{\def\strip@prefix#1>{}}{}
\@ifundefined{verbatim@nolig@list}{\def\verbatim@nolig@list{\do\`}}{}

\def\Url{\relax\ifmmode\@nomatherr$\fi 
 \UrlFont $\fam\z@ \textfont\z@\font 
 \let\do\@makeother \dospecials % verbatim catcodes
 \catcode`{\@ne \catcode`}\tw@ % except braces 
 \medmuskip0mu \thickmuskip\medmuskip \thinmuskip\medmuskip
 \@tempcnta\fam\multiply\@tempcnta\@cclvi 
 \let\do\set@mathcode \UrlOrds % ordinary characters that were special
 \advance\@tempcnta 8192 \UrlBreaks % bin
 \advance\@tempcnta 4096 \UrlBigBreaks % rel
 \advance\@tempcnta 4096 \UrlNoBreaks % open
 \let\do\set@mathact \UrlSpecials % active
 \let\do\set@mathnolig \verbatim@nolig@list % prevent ligatures 
 \@ifnextchar\bgroup\Url@z\Url@y}

\def\Url@y#1{\catcode`{11 \catcode`}11
  \def\@tempa##1#1{\Url@z{##1}}\@tempa}
\def\Url@z#1{\def\@tempa{#1}\expandafter\expandafter\expandafter\Url@use
  \expandafter\strip@prefix\meaning\@tempa\, \relax\m@th$\endgroup}
\let\Url@use\@empty

\def\set@mathcode#1{\count@`#1\advance\count@\@tempcnta\mathcode`#1\count@}
\def\set@mathact#1#2{\mathcode`#132768 \lccode`\~`#1\lowercase{\def~{#2}}}
\def\set@mathnolig#1{\ifnum\mathcode`#1<32768
   \lccode`\~`#1\lowercase{\edef~{\mathchar\number\mathcode`#1_{\/}}}%
   \mathcode`#132768 \fi}

\def\urldef#1#2{\begingroup \setbox\z@\hbox\bgroup
  \def\Url@z{\Url@def{#1}{#2}}#2}
\expandafter\ifx\csname DeclareRobustCommand\endcsname\relax
  \def\Url@def#1#2#3{\m@th$\endgroup\egroup\endgroup
    \def#1{#2{#3}}}
\else
  \def\Url@def#1#2#3{\m@th$\endgroup\egroup\endgroup
    \DeclareRobustCommand{#1}{#2{#3}}}
\fi

\def\urlstyle#1{\csname url@#1style\endcsname}

% Sample (and default) configuration:
%
\newcommand\url{\begingroup \Url}
%
\newcommand\path{\begingroup \urlstyle{tt}\Url}
%
% too many styles define \email like \address, so I will not define it.
% \newcommand\email{\begingroup \urlstyle{rm}\Url}

% Process LaTeX \package options
%
\urlstyle{tt}
\@ifundefined{ProvidesPackage}{}{
  \ProvidesPackage{url}[1996/02/06 \space ver 1.1 \space 
       Verb mode for urls, email addresses, and file names]
  \DeclareOption{hyphens}{\def\do@url@hyp{\do\-}}% allow breaks after hyphens
  \DeclareOption{obeyspaces}{\let\Url@use\relax}
  \ProcessOptions
\ifx\Url@use\relax \def\Url@use#1 #2{#1\ifx\relax#2\@empty\else
  \penalty\relpenalty\ #2\expandafter\Url@use\fi}\fi
}

\endinput
%
% url.sty  ver 1.1    6-Feb-1996   Donald Arseneau   [e-mail]
%
% This package defines "\url", a form of "\verb" that allows linebreaks,
% and can often be used in the argument to another command.  It can be
% configured to print in different formats, and is particularly useful for 
% hypertext links, email addresses, directories/paths, etc.  The font may 
% be selected using the "\urlstyle" command and pre-defined text can be 
% stored with the "\urldef" command. New url-like commands can be defined, 
% and a "\path" command is provided this way. 
%
% Usage:    Conditions:
% \url{ }   If the argument contains any "%", "#", or "^^", or ends with 
%           "\", it can't be used in the argument to another command.  
%           The argument must not contain unbalanced braces.
% \url|  |  ...where "|" is any character not used in the argument and not 
%           "{".  The same restrictions as above except that the argument
%           may contain unbalanced braces.
% \xyz      for "\xyz" a defined-url;  this can be used anywhere, no matter
%           what characters it contains.
% 
% The "\url" command is fragile, and its argument is likely to be very
% fragile, but a defined-url is robust.
%
% Package Option:  obeyspaces
% Ordinarily, all spaces are ignored in the url-text.  The "[obeyspaces]" 
% option allows spaces, but may introduce spurious spaces when a url
% containing "\" characters is given in the argument to another command.  
% So if you need to obey spaces should say "\usepackage[obeyspaces]{url}",
% and if you need both spaces and backslashes, use a `defined-url' for 
% anything with "\".
%
% Package Option:  hyphens
% Ordinarily, breaks are not allowed after "-" characters because this 
% leads to confusion. (Is the "-" part of the address or just a hyphen?)  
% The package option "[hyphens]" allows breaks after explicit hyphen 
% characters.  The "\url" command will *never ever* hyphenate words.
% 
% Defining a defined-url:
% Take for example the email address "[e-mail]" which could
% not be given (using "\url" or "\verb") in a caption or parbox due to the
% percent sign.  This address can be predefined with 
%    \urldef{\myself}\url{[e-mail]}   or
%    \urldef{\myself}\url|[e-mail]|
% and then you may use "\myself" instead of "\url{[e-mail]}"
% in an argument, and even in a moving argument like a caption because a
% defined-url is robust.
%
% Style: 
% You can switch the style of printing using "\urlstyle{tt}", where "tt"
% can be any defined style.  The pre-defined styles are "tt", "rm", "sf", 
% and "same" which all allow the same linebreaks but different fonts -- 
% the first three select a specific font and the "same" style uses the
% current text font.  You can define your own styles with different fonts 
% and/or line-breaking by following the explanations below.  The "\url" 
% command follows whatever the currently-set style dictates.
%
% Alternate commands:
% It may be desireable to have different things treated differently, each
% in a predefined style; e.g., if you want directory paths to always be 
% in tt and email addresses to be rm, then you would define new url-like
% commands as follows:
%
%    \newcommand\email{\begingroup \urlstyle{rm}\Url}
%    \newcommand\directory{\begingroup \urlstyle{tt}\Url}
%
% You must follow this format closely, and NOTE that the final command is 
% "\Url", not "\url".  In fact, the "\directory" example is exactly the 
% "\path" definition which is pre-defined in the package.  If you look 
% above, you will see that "\url" is defined with
%    \newcommand\url{\begingroup \Url}
% I.e., using whatever url-style has been selected.
%
% You can make a defined-url for these other styles, using the usual 
% "\urldef" command as in this example:
%
%    \urldef{\myself}{\email}{[e-mail]}
%
% which makes "\myself" act like "\email{[e-mail]}",
% if the "\email" command is defined as above.  The "\myself" command is
% robust.
%
% Defining styles:
% Before describing how to customize the printing style, it is best to 
% mention something about the unusual implementation of "\url".  Although
% the material is textual in nature, and the font specification required
% is a text-font command, the text is actually typeset in *math* mode.
% This allows the context-sensitive linebreaking, but also accounts for
% the default behavior of ignoring spaces.  Now on to defining styles.
%
% To change the font or the list of characters that allow linebreaks, you
% could redefine the commands "\UrlFont", "\UrlBreaks", "\UrlSpecials" etc.
% directly in the document, but it is better to define a new `url-style' 
% (following the example of "\url@ttstyle" and "\url@rmstyle") which defines 
% all of "\UrlBigbreaks", "\UrlNoBreaks", "\UrlBreaks", "\UrlSpecials", and 
% "\UrlFont".
%
% Changing font:
% The "\UrlFont" command selects the font.  The definition of "\UrlFont"
% done by the pre-defined styles varies to cope with a variety of LaTeX
% font selection schemes, but it could be as simple as "\def\UrlFont{\tt}".
% In addition to setting "\UrlFont", some characters will probably need 
% to be defined in the "\UrlSpecials" list because most fonts don't have 
% all the standard input characters.  See the definition of "\url@rmstyle", 
% which implements "\urlstyle{rm}".  Or even better, follow the definition
% of "\url@sfstyle", which executes "\url@rmstyle" and then redefines
% just "\UrlFont".  The nominal format for each special character "c" 
% in the "\UrlSpecials" list is: "\do\c{<definition>}", but you can 
% include other definitions too.
%
% Changing linebreaks:
% The list of characters that allow line-breaks is given by "\UrlBreaks" 
% and "\UrlBigBreaks", which have the format "\do\c" for character "c". 
% The differences are that `BigBreaks' have a lower penalty and have 
% different breakpoints when in sequence (as in "http://"): `BigBreaks' 
% are treated as mathrels while `Breaks' are mathbins (see The TeXbook, 
% p.170). In particular, a series of `BigBreak' characters will break at 
% the end and only at the end; a series of `Break' characters will break 
% after the first and after every following *pair*; there will be no 
% break after a `Break' character if a `BigBreak' follows.  In the case 
% of "http://" it doesn't matter whether ":" is a `Break' or `BigBreak' --
% the breaks are the same in either case; but for DECnet nodes with "::"
% it is important to prevent breaks *between* the colons, and that is why 
% colons are `BigBreaks'.
%
% It is possible for characters to prevent breaks after the next following 
% character (I use this for parentheses).  Specify these in "\UrlNoBreaks". 
%
% You can do arbitrarily complex things with characters by making them 
% active in math mode (mathcode hex-8000) and specifying the definition(s)
% in "\UrlSpecials".  This is used in the rm and sf styles to handle 
% several characters that are not present in fonts.
%
% If all this sounds confusing ... well, it is!  But I hope you won't need 
% to redefine breakpoints -- the default assignments seem to work well for 
% a wide variety of applications.  If you do need to make changes, you can 
% test for breakpoints using regular math mode and the characters "+=(a".
%
% Yet more flexibility:
% You can also set up url.sty to do multiple things with the verbatim text
% by defining "\Url@use", but the format of the definition is special:
%
%    \def\Url@use#1\,{ ... do things with #1 ... }
%
% Yes, that is "#1" followed by "\," then the definition.  For example, 
% to put a hypertext link in the DVI file:
%
%    \def\Url@use#1\,{\special{html:<a href="#1">}#1\special{html:</a>}}
%
% The End
% ver 1.1 6-Feb-1996:  
% Fix hyphens that wouldn't break and ligatures that weren't suppressed.

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