
wenzelm@26862: % underscore.sty     21-Sep-2005   Donald Arseneau   asnd@triumf.ca
wenzelm@26862: % Make the "_" character print as "\textunderscore" in text.
wenzelm@26862: % Copyright 1998,2001,2005,2006 Donald Arseneau;  
wenzelm@26862: % License: LPPL version 1.2 or later.
wenzelm@26862: % Instructions follow after the definitions.
wenzelm@26862: 
wenzelm@26862: \ProvidesPackage{underscore}[2006/09/13]
wenzelm@26862: 
wenzelm@26862: \begingroup
wenzelm@26862:  \catcode`\_=\active
wenzelm@26862:  \gdef _{% \relax % No relax gives a small vulnerability in alignments
wenzelm@26862:    \ifx\if@safe@actives\iftrue % must be outermost test!
wenzelm@26862:       \string_%
wenzelm@26862:    \else
wenzelm@26862:       \ifx\protect\@typeset@protect
wenzelm@26862:          \ifmmode \sb \else \BreakableUnderscore \fi
wenzelm@26862:       \else
wenzelm@26862:          \ifx\protect\@unexpandable@protect \noexpand_%
wenzelm@26862:          \else \protect_%
wenzelm@26862:       \fi\fi
wenzelm@26862:     \fi}
wenzelm@26862:   \global\let\ActiveUnderscore=_
wenzelm@26862:   \gdef\normalUnderscoreDef{\let_\ActiveUnderscore}
wenzelm@26862: \endgroup
wenzelm@26862: 
wenzelm@26862: % At begin: set catcode; fix \long \ttdefault so I can use it in comparisons; 
wenzelm@26862: % reapply definition of active _ in output routine (\@firstofone to strip
wenzelm@26862: % away braces, so avoiding deeper nesting).
wenzelm@26862: \AtBeginDocument{%
wenzelm@26862:   {\immediate\write\@auxout{\catcode\number\string`\_ \string\active}}%
wenzelm@26862:   \catcode\string`\_\string=\active
wenzelm@26862:   \edef\ttdefault{\ttdefault}%
wenzelm@26862:   \output=\expandafter\expandafter\expandafter
wenzelm@26862:      {\expandafter\expandafter\expandafter\normalUnderscoreDef
wenzelm@26862:       \expandafter\@firstofone\the\output}%
wenzelm@26862: }
wenzelm@26862: 
wenzelm@26862: \newcommand{\BreakableUnderscore}{\leavevmode\nobreak\hskip\z@skip
wenzelm@26862:  \ifx\f@family\ttdefault \string_\else \textunderscore\fi
wenzelm@26862:  \usc@dischyph\nobreak\hskip\z@skip}
wenzelm@26862: 
wenzelm@26862: \DeclareRobustCommand{\_}{%
wenzelm@26862:   \ifmmode \nfss@text{\textunderscore}\else \BreakableUnderscore \fi}
wenzelm@26862: 
wenzelm@26862: 
wenzelm@26862: \let\usc@dischyph\@dischyph
wenzelm@26862: \DeclareOption{nohyphen}{\def\usc@dischyph{\discretionary{}{}{}}}
wenzelm@26862: \DeclareOption{strings}{\catcode`\_=\active}
wenzelm@26862: 
wenzelm@26862: \ProcessOptions
wenzelm@26862: \ifnum\catcode`\_=\active\else \endinput \fi
wenzelm@26862: 
wenzelm@26862: %%%%%%%%   Redefine commands that use character strings   %%%%%%%%
wenzelm@26862: 
wenzelm@26862: \@ifundefined{UnderscoreCommands}{\let\UnderscoreCommands\@empty}{}
wenzelm@26862: \expandafter\def\expandafter\UnderscoreCommands\expandafter{%
wenzelm@26862:   \UnderscoreCommands
wenzelm@26862:   \do\include \do\includeonly
wenzelm@26862:   \do\@input \do\@iinput \do\InputIfFileExists
wenzelm@26862:   \do\ref \do\pageref \do\newlabel
wenzelm@26862:   \do\bibitem \do\@bibitem \do\cite \do\nocite \do\bibcite
wenzelm@26862:   \do\Ginclude@graphics \do\@setckpt
wenzelm@26862: }
wenzelm@26862: 
wenzelm@26862: % Macro to redefine a macro to pre-process its string argument
wenzelm@26862: % with \protect -> \string.
wenzelm@26862: \def\do#1{% Avoid double processing if user includes command twice!
wenzelm@26862:  \@ifundefined{US\string_\expandafter\@gobble\string#1}{%
wenzelm@26862:    \edef\@tempb{\meaning#1}% Check if macro is just a protection shell...
wenzelm@26862:    \def\@tempc{\protect}%
wenzelm@26862:    \edef\@tempc{\meaning\@tempc\string#1\space\space}%
wenzelm@26862:    \ifx\@tempb\@tempc % just a shell: hook into the protected inner command
wenzelm@26862:      \expandafter\do
wenzelm@26862:        \csname \expandafter\@gobble\string#1 \expandafter\endcsname
wenzelm@26862:    \else % Check if macro takes an optional argument
wenzelm@26862:      \def\@tempc{\@ifnextchar[}%
wenzelm@26862:      \edef\@tempa{\def\noexpand\@tempa####1\meaning\@tempc}%
wenzelm@26862:      \@tempa##2##3\@tempa{##2\relax}%
wenzelm@26862:      \edef\@tempb{\meaning#1\meaning\@tempc}%
wenzelm@26862:      \edef\@tempc{\noexpand\@tempd \csname
wenzelm@26862:         US\string_\expandafter\@gobble\string#1\endcsname}%
wenzelm@26862:      \if \expandafter\@tempa\@tempb \relax 12\@tempa % then no optional arg
wenzelm@26862:        \@tempc #1\US@prot
wenzelm@26862:      \else  % There is optional arg
wenzelm@26862:        \@tempc #1\US@protopt
wenzelm@26862:      \fi
wenzelm@26862:    \fi
wenzelm@26862:  }{}}
wenzelm@26862: 
wenzelm@26862: \def\@tempd#1#2#3{\let#1#2\def#2{#3#1}}
wenzelm@26862: 
wenzelm@26862: \def\US@prot#1#2{\let\@@protect\protect \let\protect\string
wenzelm@26862:   \edef\US@temp##1{##1{#2}}\restore@protect\US@temp#1}
wenzelm@26862: \def\US@protopt#1{\@ifnextchar[{\US@protarg#1}{\US@prot#1}}
wenzelm@26862: \def\US@protarg #1[#2]{\US@prot{{#1[#2]}}}
wenzelm@26862: 
wenzelm@26862: \UnderscoreCommands
wenzelm@26862: \let\do\relax \let\@tempd\relax  % un-do
wenzelm@26862: 
wenzelm@26862: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
wenzelm@26862: 
wenzelm@26862: \endinput
wenzelm@26862: 
wenzelm@26862: underscore.sty    13-Sep-2006  Donald Arseneau
wenzelm@26862: 
wenzelm@26862: Features:
wenzelm@26862: ~~~~~~~~~
wenzelm@26862: The "\_" command (which normally prints an underscore character or
wenzelm@26862: facsimile) is altered so that the hyphenation of constituent words
wenzelm@26862: is not affected, and hyphenation is permitted after the underscore.
wenzelm@26862: For example, "compound\_fracture" hyphenates as com- pound\_- frac- ture.
wenzelm@26862: If you prefer the underscore to break without a hyphen (but still with 
wenzelm@26862: the same rules for explicit hyphen-breaks) then use the [nohyphen]
wenzelm@26862: package option.
wenzelm@26862: 
wenzelm@26862: A simple "_" acts just like "\_" in text mode, but makes a subscript
wenzelm@26862: in math mode: activation_energy $E_a$
wenzelm@26862: 
wenzelm@26862: Both forms use an underscore character if the font encoding contains
wenzelm@26862: one (e.g., "\usepackage[T1]{fontenc}" or typewriter fonts in any encoding),
wenzelm@26862: but they use a rule if there is no proper character.
wenzelm@26862: 
wenzelm@26862: Deficiencies:
wenzelm@26862: ~~~~~~~~~~~~~
wenzelm@26862: The skips and penalties ruin any kerning with the underscore character
wenzelm@26862: (when a character is used).  However, there doesn't seem to be much, if
wenzelm@26862: any, such kerning in the ec fonts, and there is never any kerning with
wenzelm@26862: a rule.
wenzelm@26862: 
wenzelm@26862: You must avoid "_" in file names and in cite or ref tags, or you must use 
wenzelm@26862: the babel package, with its active-character controls, or you must give 
wenzelm@26862: the [strings] option, which attempts to redefine several commands (and 
wenzelm@26862: may not work perfectly).  Even without the [strings] option or babel, you 
wenzelm@26862: can use occasional underscores like: "\include{file\string_name}".
wenzelm@26862: 
wenzelm@26862: Option: [strings]
wenzelm@26862: ~~~~~~~~~~~~~~~~~
wenzelm@26862: The default operation is quite simple and needs no customization; but
wenzelm@26862: you must avoid using "_" in any place where LaTeX uses an argument as
wenzelm@26862: a string of characters for some control function or as a name.  These
wenzelm@26862: include the tags for "\cite" and "\ref", file names for "\input", 
wenzelm@26862: "\include", and "\includegraphics", environment names, counter names,
wenzelm@26862: and placement parameters (like "[t]").  The problem with these contexts
wenzelm@26862: is that they are `moving arguments' but LaTeX does not `switch on' the
wenzelm@26862: "\protect" mechanism for them.
wenzelm@26862: 
wenzelm@26862: If you need to use the underscore character in these places, the package
wenzelm@26862: option [strings] is provided to redefine commands that take such a string
wenzelm@26862: argument so that protection is applied (with "\protect" being "\string").
wenzelm@26862: The list of commands is given in "\UnderscoreCommands", with "\do" before
wenzelm@26862: each; plus several others covering "\input", "\includegraphics, "\cite", 
wenzelm@26862: "\ref", and their variants.  Not included are many commands regarding font 
wenzelm@26862: names, everything with counter names, environment names, page styles, and 
wenzelm@26862: versions of "\ref" and "\cite" defined by external packages (e.g., "\vref" 
wenzelm@26862: and "\citeyear").
wenzelm@26862: 
wenzelm@26862: You can add to the list of supported commands by defining "\UnderscoreCommands"
wenzelm@26862: before loading this package; e.g.
wenzelm@26862: 
wenzelm@26862:    \usepackage{chicago}
wenzelm@26862:    \newcommand{\UnderscoreCommands}{%   (\cite already done)
wenzelm@26862:      \do\citeNP \do\citeA \do\citeANP \do\citeN \do\shortcite
wenzelm@26862:      \do\shortciteNP \do\shortciteA \do\shortciteANP \do\shortciteN
wenzelm@26862:      \do\citeyear \do\citeyearNP
wenzelm@26862:    }
wenzelm@26862:    \usepackage[strings]{underscore}
wenzelm@26862: 
wenzelm@26862: Not all commands can be supported this way!  Only commands that take a
wenzelm@26862: string argument *first* can be protected.  One optional argument before
wenzelm@26862: the string argument is also permitted, as exemplified by "\cite": both
wenzelm@26862: "\cite{tags}" and "\cite[text]{tags}" are allowed.  A command like
wenzelm@26862: "\@addtoreset" which takes two counter names as arguments could not
wenzelm@26862: be protected by listing it in "\UnderscoreCommands".
wenzelm@26862: 
wenzelm@26862: *When you use the [strings] option, you must load this package
wenzelm@26862: last* (or nearly last).
wenzelm@26862: 
wenzelm@26862: There are two reasons: 1) The redefinitions done for protection must come
wenzelm@26862: after other packages define their customized versions of those commands.
wenzelm@26862: 2) The [strings] option requires the "_" character to be activated immediately
wenzelm@26862: in order for the cite and ref tags to be read properly from the .aux file
wenzelm@26862: as plain strings, and this catcode setting might disrupt other packages.
wenzelm@26862: 
wenzelm@26862: The babel package implements a protection mechanism for many commands,
wenzelm@26862: and will be a complete fix for most documents without the [strings] option.
wenzelm@26862: Many add-on packages are compatible with babel, so they will get the
wenzelm@26862: strings protection also.  However, there are several commands that are 
wenzelm@26862: not covered by babel, but can easily be supported by the [strings] and 
wenzelm@26862: "\UnderscoreCommands" mechanism.  Beware that using both [strings] and
wenzelm@26862: babel might lead to conflicts, but none are seen yet (load babel last).
wenzelm@26862: 
wenzelm@26862: Implementation Notes:
wenzelm@26862: ~~~~~~~~~~~~~~~~~~~~~
wenzelm@26862: The first setting of "_" to be an active character is performed in a local
wenzelm@26862: group so as to not interfere with other packages.  The catcode setting
wenzelm@26862: is repeated with "\AtBeginDocument" so the definition is in effect for the
wenzelm@26862: text.  However, the catcode setting is repeated immediately when the
wenzelm@26862: [strings] option is detected.
wenzelm@26862: 
wenzelm@26862: The definition of the active "_" is essentially:
wenzelm@26862: 
wenzelm@26862:        \ifmmode \sb \else \BreakableUnderscore \fi
wenzelm@26862: 
wenzelm@26862: where "\sb" retains the normal subscript meaning of "_" and where
wenzelm@26862: "\BreakableUnderscore" is essentially "\_".  The rest of the definition
wenzelm@26862: handles the "\protect"ion without causing "\relax" to be inserted before
wenzelm@26862: the character.
wenzelm@26862: 
wenzelm@26862: "\BreakableUnderscore" uses "\nobreak\hskip\z@skip" to separate the
wenzelm@26862: underscore from surrounding words, thus allowing TeX to hyphenate them,
wenzelm@26862: but preventing free breaks around the underscore. Next, it checks the
wenzelm@26862: current font family, and uses the underscore character from tt fonts or
wenzelm@26862: otherwise "\textunderscore" (which is a character or rule depending on
wenzelm@26862: the font encoding).  After the underscore, it inserts a discretionary
wenzelm@26862: hyphenation point as "\usc@dischyph", which is usually just "\-"
wenzelm@26862: except that it still works in the tabbing environment, although it
wenzelm@26862: will give "\discretionary{}{}{}" under the [nohyphen] option.  After
wenzelm@26862: that, another piece of non-breaking interword glue is inserted. 
wenzelm@26862: Ordinarily, the comparison "\ifx\f@family\ttdefault" will always fail 
wenzelm@26862: because "\ttdefault" is `long' whereas "\f@family" is not (boooo hisss),
wenzelm@26862: but "\ttdefault" is redefined to be non-long by "\AtBeginDocument".
wenzelm@26862: 
wenzelm@26862: The "\_" command is then defined to use "\BreakableUnderscore".
wenzelm@26862: 
wenzelm@26862: If the [strings] option is not given, then that is all!
wenzelm@26862: 
wenzelm@26862: Under the [strings] option, the list of special commands is processed to:
wenzelm@26862: 
wenzelm@26862:  - retain the original command as "\US_"*command* (e.g., "\US_ref")
wenzelm@26862:  - redefine the command as "\US@prot\US_command" for ordinary commands
wenzelm@26862:    ("\US@prot\US_ref") or as "\US@protopt\US_command" when an optional
wenzelm@26862:    argument is possible (e.g., "\US@protopt\US_bibitem").
wenzelm@26862:  - self-protecting commands ("\cite") retain their self-protection.
wenzelm@26862: 
wenzelm@26862: Diagnosing the state of the pre-existing command is done by painful
wenzelm@26862: contortions involving "\meaning".
wenzelm@26862: 
wenzelm@26862: "\US@prot" and "\US@protopt" read the argument, process it with 
wenzelm@26862: "\protect" enabled, then invoke the saved "\US_command".
wenzelm@26862: 
wenzelm@26862: Modifications:
wenzelm@26862: ~~~~~~~~~~~~~~
wenzelm@26862: 13-Sep-2006  Reassert my definition in the output routine (listings).
wenzelm@26862: 21-Sep-2005  \includegraphics safe.
wenzelm@26862: 12-Oct-2001  Babel (safe@actives) compatibility and [nohyphen] option.
wenzelm@26862: 
wenzelm@26862: Test file integrity:  ASCII 32-57, 58-126:  !"#$%&'()*+,-./0123456789
wenzelm@26862: :;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~




