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Subject: [Boost-commit] svn:boost r48805 - sandbox/committee/concepts/stdlib
From: dgregor_at_[hidden]
Date: 2008-09-17 01:25:05

Author: dgregor
Date: 2008-09-17 01:25:04 EDT (Wed, 17 Sep 2008)
New Revision: 48805

Add underscore
   sandbox/committee/concepts/stdlib/underscore.sty (contents, props changed)

Added: sandbox/committee/concepts/stdlib/underscore.sty
--- (empty file)
+++ sandbox/committee/concepts/stdlib/underscore.sty 2008-09-17 01:25:04 EDT (Wed, 17 Sep 2008)
@@ -0,0 +1,232 @@
+% underscore.sty 12-Oct-2001 Donald Arseneau asnd_at_[hidden]
+% Make the "_" character print as "\textunderscore" in text.
+% Copyright 1998,2001 Donald Arseneau; Distribute freely if unchanged.
+% Instructions follow after the definitions.
+ \catcode`\_=\active
+ \gdef_{% \relax % No relax gives a small vulnerability in alignments
+ \ifx\if_at_safe@actives\iftrue % must be outermost test!
+ \string_%
+ \else
+ \ifx\protect\@typeset_at_protect
+ \ifmmode \sb \else \BreakableUnderscore \fi
+ \else
+ \ifx\protect\@unexpandable_at_protect \noexpand_%
+ \else \protect_%
+ \fi\fi
+ \fi}
+% At begin: set catcode; fix \long \ttdefault so I can use it in comparisons;
+ {\immediate\write\@auxout{\catcode\number\string`\_ \string\active}}%
+ \catcode\string`\_\string=\active
+ \edef\ttdefault{\ttdefault}%
+ \ifx\f_at_family\ttdefault \string_\else \textunderscore\fi
+ \usc_at_dischyph\nobreak\hskip\z_at_skip}
+ \ifmmode \nfss_at_text{\textunderscore}\else \BreakableUnderscore \fi}
+\ifnum\catcode`\_=\active\else \endinput \fi
+%%%%%%%% Redefine commands that use character strings %%%%%%%%
+ \UnderscoreCommands
+ \do\include \do\includeonly
+ \do\@input \do\@iinput \do\InputIfFileExists
+ \do\ref \do\pageref \do\newlabel
+ \do\bibitem \do\@bibitem \do\cite \do\nocite \do\bibcite
+% Macro to redefine a macro to pre-process its string argument
+% with \protect -> \string.
+\def\do#1{% Avoid double processing if user includes command twice!
+ \@ifundefined{US\string_\expandafter\@gobble\string#1}{%
+ \edef\@tempb{\meaning#1}% Check if macro is just a protection shell...
+ \def\@tempc{\protect}%
+ \edef\@tempc{\meaning\@tempc\string#1\space\space}%
+ \ifx\@tempb\@tempc % just a shell: hook into the protected inner command
+ \expandafter\do
+ \csname \expandafter\@gobble\string#1 \expandafter\endcsname
+ \else % Check if macro takes an optional argument
+ \def\@tempc{\@ifnextchar[}%
+ \edef\@tempa{\def\noexpand\@tempa####1\meaning\@tempc}%
+ \@tempa##2##3\@tempa{##2\relax}%
+ \edef\@tempb{\meaning#1\meaning\@tempc}%
+ \edef\@tempc{\noexpand\@tempd \csname
+ US\string_\expandafter\@gobble\string#1\endcsname}%
+ \if \expandafter\@tempa\@tempb \relax 12\@tempa % then no optional arg
+ \@tempc #1\US_at_prot
+ \else % There is optional arg
+ \@tempc #1\US_at_protopt
+ \fi
+ \fi
+ }{}}
+\def\US_at_prot#1#2{\let\@@protect\protect \let\protect\string
+ \edef\US_at_temp##1{##1{#2}}\restore_at_protect\US_at_temp#1}
+\def\US_at_protarg #1[#2]{\US_at_prot{{#1[#2]}}}
+\let\do\relax \let\@tempd\relax % un-do
+underscore.sty 12-Oct-2001 Donald Arseneau
+\_ prints an underscore so that the hyphenation of constituent words
+is not affected and hyphenation is permitted after the underscore.
+For example, "compound\_fracture" hyphenates as com- pound_- frac- ture.
+If you prefer the underscore to break without a hyphen (but still with
+the same rules for explicit hyphen-breaks) then use the [nohyphen]
+package option.
+A simple _ acts just like \_ in text mode, but makes a subscript in
+math mode: activation_energy $E_a$
+Both forms use an underscore character if the font encoding contains
+one (e.g., "\usepackage[T1]{fontenc}" or typewriter fonts in any encoding),
+but they use a rule if the there is no proper character.
+The skips and penalties ruin any kerning with the underscore character
+(when a character is used). However, there doesn't seem to be much, if
+any, such kerning in the ec fonts, and there is never any kerning with
+a rule.
+You must avoid "_" in file names and in cite or ref tags, or you must use
+the babel package, with its active-character controls, or you must give
+the [strings] option, which attempts to redefine several commands (and
+may not work perfectly). Even without the [strings] option or babel, you
+can use occasional underscores like: "\include{file\string_name}".
+Option: [strings]
+The default operation is quite simple and needs no customization; but
+you must avoid using "_" in any place where LaTeX uses an argument as
+a string of characters for some control function or as a name. These
+include the tags for \cite and \ref, file names for \input, \include,
+and \includegraphics, environment names, counter names, and placement
+parameters (like "[t]"). The problem with these contexts is that they
+are `moving arguments' but LaTeX does not `switch on' the \protect
+mechanism for them.
+If you need to use the underscore character in these places, the package
+option [strings] is provided to redefine commands taking a string argument
+so that the argument is protected (with \protect -> \string). The list
+of commands is given in "\UnderscoreCommands", with "\do" before each,
+covering \cite, \ref, \input, and their variants. Not included are many
+commands regarding font names, everything with counter names, environment
+names, page styles, and versions of \ref and \cite defined by external
+packages (e.g. \vref and \citeyear).
+You can add to the list of supported commands by defining \UnderscoreCommands
+before loading this package; e.g.
+ \usepackage{chicago}
+ \newcommand{\UnderscoreCommands}{% (\cite already done)
+ \do\citeNP \do\citeA \do\citeANP \do\citeN \do\shortcite
+ \do\shortciteNP \do\shortciteA \do\shortciteANP \do\shortciteN
+ \do\citeyear \do\citeyearNP
+ }
+ \usepackage[strings]{underscore}
+Not all commands can be supported this way! Only commands that take a
+string argument *first* can be protected. One optional argument before
+the string argument is also permitted, as exemplified by \cite: both
+\cite{tags} and \cite[text]{tags} are allowed. A command like
+\@addtoreset which takes two counter names as arguments could not
+be protected by adding it to \UnderscoreCommands.
+!! When you use the [strings] option, you must load this package !!
+!! last (or nearly last). !!
+There are two reasons: 1) The redefinitions done for protection must come
+after other packages define their customized versions of those commands.
+2) The [strings] option requires the _ character to be activated immediately
+in order for the cite and ref tags to be read properly from the .aux file
+as plain strings, and this catcode setting might disrupt other packages.
+The babel package implements a protection mechanism for many commands,
+and will be a complete fix for most documents without the [strings] option.
+Many add-on packages are compatible with babel, so they will get the
+strings protection also. However, there are several commands that are
+not covered by babel, but can easily be supported by the [strings] and
+\UnderscoreCommands mechanism. Beware that using both [strings] and babel
+may lead to conflicts, but does appear to work (load babel last).
+Implementation Notes:
+The first setting of "_" to be an active character is performed in a local
+group so as to not interfere with other packages. The catcode setting
+is repeated with \AtBeginDocument so the definition is in effect for the
+text. However, the catcode setting is repeated immediately when the
+[strings] option is detected.
+The definition of the active "_" is essentially:
+ \ifmmode \sb \else \BreakableUnderscore \fi
+where "\sb" retains the normal subscript meaning of "_" and where
+"\BreakableUnderscore" is essentially "\_". The rest of the definition
+handles the "\protect"ion without causing \relax to be inserted before
+the character.
+\BreakableUnderscore uses "\nobreak\hskip\z_at_skip" to separate the
+underscore from surrounding words, thus allowing TeX to hyphenate them,
+but preventing free breaks around the underscore. Next, it checks the
+current font family, and uses the underscore character from tt fonts or
+otherwise \textunderscore (which is a character or rule depending on
+the font encoding). After the underscore, it inserts a discretionary
+hyphenation point as "\usc_at_dischyph", which is usually just "\-"
+except that it still works in the tabbing environment, although it
+will give "\discretionary{}{}{}" under the [nohyphen] option. After
+that, another piece of non-breaking interword glue is inserted.
+Ordinarily, the comparison "\ifx\f_at_family\ttdefault" will always fail
+because \ttdefault is `long' where \f_at_family is not (boooo hisss), but
+\ttdefault is redefined to be non-long by "\AtBeginDocument".
+The "\_" command is then defined to use "\BreakableUnderscore".
+If the [strings] option is not given, then that is all!
+Under the [strings] option, the list of special commands is processed to:
+- retain the original command as \US_command (\US_ref)
+- redefine the command as \US_at_prot\US_command for ordinary commands
+ (\ref -> \US_at_prot\US_ref) or as \US_at_protopt\US_command when an optional
+ argument is possible (\bibitem -> \US_at_protopt\US_bibitem).
+- self-protecting commands (\cite) retain their self-protection.
+Diagnosing the state of the pre-existing command is done by painful
+contortions involving \meaning.
+\US_at_prot and \US_at_protopt read the argument, process it with \protect
+enabled, then invoke the saved \US_command.
+12-Oct-2001 Babel (safe_at_actives) compatibility and [nohyphen] option.
+Test file integrity: ASCII 32-57, 58-126: !"#$%&'()*+,-./0123456789

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