AlgorithmNotes/Foundations/overview/clrscode3e.sty

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% clrscode3e.sty

% See the document "Using the clrscode3e Package in LaTeX 2e" for
% examples.

% Package for producing pseudocode in the style of Cormen, Leiserson,
% Rivest, and Stein, Introduction to Algorithms, Third edition.

% LIMITATION: This package works only if each procedure has at most 99
% numbered lines of code.

% Each pseudocode procedure is typeset within a codebox environment,
%   \begin{codebox}...\end{codebox}.

% Normally, the first line within the codebox environment is a \Procname
% command.  The argument of the \Procname command is a math-mode
% expression consisting of the procedure name and its parameters.  The
% name of the procedure itself goes within a \proc command.  Example:
%   \Procname{$\proc{Matrix-Multiply}(A,B)$}
% The \Procname command is optional.

% To typeset the name of a procedure (e.g., Matrix-Multiply) in small
% caps, use the \proc command:
%   \proc{Matrix-Multiply}

% To typeset the name of a constant (e.g., nil) in small caps, use the
% \const command:
%   \const{nil}

% To typeset the name of an identifier (e.g., rank) in regular italics,
% use the \id command:
%   \id{rank}

% To typeset the name of a fixed function (e.g., sin) in roman, use the
% \func command:
%   \func{sin}
% (Note that several fixed functions, like sin, are already built into
% LaTeX.)

% The \proc, \const, \id, and \func commands not only use the correct
% font, they also perform the important service of interpreting a dash
% as a hyphen, rather than as a minus sign.  These commands may be used
% either in or out of math mode.

% For attributes, use the various forms of the \attrib commands.

% Other than the \Procname line, all lines begin with either \li (for a
% numbered line) or \zi (for an unnumbered line).  The following
% commands are provided for typesetting keywords and handling automatic
% indentation:

% Loops: \For, \To, \By, \Downto, \Do, \While, \Repeat, \Until
% Selection: \If, \Then, \Else, \ElseIf, \ElseNoIf
% Jumps: \Return, \Error, \Goto
% Multithreading: \Spawn, \Sync, \Parfor
% Comments: \Comment, \RComment, \CommentSymbol
% Indentation: \Indentmore, \Startalign, \Stopalign

% \label commands appearing in or after the first numbered line in a
% codebox resolve to the number of the most recent numbered line.

% \twodots produces the ".." notation used for subarrays.

% Written for general distribution by Thomas H. Cormen, March 2009.

% The author grants permission for anyone to use this macro package and
% to distribute it unchanged without further restriction.  If you choose
% to modify this package, you must indicate that you have modified it
% prior to your distributing it.  I don't want to get bug reports about
% changes that *you* have made!

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\ProvidesPackage{clrscode3e}
\RequirePackage{graphics}	% needed for \scalebox command

% The \useregularv command is because we used a different lowercase v
% in math mode in the book.  Most users of the clrscode3e package will
% use the standard lowercase v in math mode, and so the \useregularv
% command is a no-op for them.
\ifdefined\useregularv\else\newcommand{\useregularv}{}\fi

% Commands for typesetting constants, procedure names, identifiers, and
% fixed functions.
\newcommand{\const}[1]{\textnormal{\scshape#1}}
\newcommand{\proc}[1]{\textnormal{\scshape#1}}
\newcommand{\text@hyphens}{\mathcode`\-=`\-\relax}
\newcommand{\func}[1]{%
  \ensuremath{{\useregularv\mathop{\text@hyphens\operator@font#1}\nolimits}}}
\newcommand{\id}[1]{%
  \ensuremath{\mathit{\text@hyphens#1}}}

% Commands for typesetting object attributes.  All of these commands
% may be used either in or out of math mode.

% Definitions:
% An i-string is a string that you would use in an \id command,
%   typically one or more non-Greek letters, numerals, or dashes.
% An x-string is a string that you would not use in an \id command,
%   typically because it has a subscript or one or more Greek letters.
% A single non-Greek letter can be either an i-string or an x-string.

% Most of the time, we use the \attrib command, which assumes that its
% first argument, the object name, is an x-string and its second
% argument, the attribute name, is an i-string.  Examples of the
% \attrib command: \attrib{A}{length}, \attrib{x}{next},
% \attrib{\rho}{next-item}.  \attrib is just a direct call to the
% \attribxi macro.

% The four macros \attribxi, \attribxx, \attribix, and \attribii each
% take two arguments.  The two letters at the end of the macro name
% determine, in order, how each argument is treated.  x indicates that
% the argument should be an x-string, and i indicates that the
% argument should be an i-string.

% Because we use a single letter to indicate most objects and a string
% of one or more letters to indicate most attribute names, \attribxi
% is the most common macro we use.  That's why \attrib is just a
% direct call to \attribxi.

% Use \attribxx when the object name is an x-string and the object
% name is also an x-string, for example, when the attribute name has a
% subscript: \attribxx{x}{c_i} or \attrib{x}{\id{key}_i}.  Another
% time you would use \attribxx is when the attribute name is a Greek
% letter: \attrib{v}{\pi}.

% When the object name has more than one letter, it is usually an
% i-string.  In this case, use \attribii or \attribix, depending on
% the attribute name: \attribii{item}{key}, \attribii{prev-item}{np},
% \attribix{item}{\pi}.

% The \attribb, \attribbb, \attribbbb, and \attribbxxi macros are for
% cascading attributes.  They just call the appropriate \attribxi and
% \attribxx commands.  For one level of cascading, use \attribb:
% \attribb{x}{left}{size}.  For two levels, use \attribbb:
% \attribbb{y}{p}{left}{size}.  For three levels, use \attribbbb (but
% no examples in the book use this macro).  The \attribbxxi macro is
% for one level of cascading where the first attribute given is an
% x-string: \attribbxxi{x}{c_i}{n}.

% When the object is an edge of a graph, specified by two vertices,
% use \attribe or \attribex: \attribe{u}{v}{f}, \attribex{u}{v}{c'}.

\newcommand{\attribxi}[2]{\ensuremath{#1.\hspace*{1pt}\id{#2}}}
\newcommand{\attribxx}[2]{\ensuremath{#1.\hspace*{1pt}#2}}
\newcommand{\attribix}[2]{\ensuremath{\id{#1}\hspace*{1pt}.#2}}
\newcommand{\attribii}[2]{\ensuremath{\id{#1}\hspace*{1pt}.\hspace*{1pt}\id{#2}}}
\newcommand{\attrib}[2]{\attribxi{#1}{#2}}
\newcommand{\attribe}[3]{\attribxi{(#1,#2)}{#3}}
\newcommand{\attribex}[3]{\attribxx{(#1,#2)}{#3}}
\newcommand{\attribb}[3]{\attribxi{\attribxi{#1}{#2}}{#3}}
\newcommand{\attribbb}[4]{\attribxi{\attribb{#1}{#2}{#3}}{#4}}
\newcommand{\attribbbb}[5]{\attribxi{\attribbb{#1}{#2}{#3}{#4}}{#5}}
\newcommand{\attribbxxi}[3]{\attribxi{\attribxx{#1}{#2}}{#3}}

% Command for typesetting subarray ranges.
\newcommand{\twodots}{\mathinner{\ldotp\ldotp}}

% The codelinenumber counter counts the current line number.
\newcounter{codelinenumber}

% The indent counter keeps track of the current indentation level.
\newcounter{indent}

% The \iffirstcodeline command tells us whether we are about to
% produce the first line other than the procedure declaration.
\newif\iffirstcodeline\firstcodelinetrue

% The \zeroli command makes it so that we're about to produce the
% first line other than the procedure declaration.
\newcommand{\zeroli}{\setcounter{codelinenumber}{0}%
\setcounter{indent}{0}%
\firstcodelinetrue}

% \digitwidth gives the width of a single digit.  All digits are the
% same width.  We'll need this amount to do the right thing for line
% numbers.
\newlength{\digitwidth}
\settowidth{\digitwidth}{0}

% The \li command bumps the counter, outputs it, and skips some space
% A \label cmd for a given numbered line is allowed to appear after the
% \\, as in 
%	\li $x\gets y$  \label{li:assign-x}
% But if \li merely set \@currentlabel in the usual way via
% \refstepcounter, the value of \@currentlabel does not persist outside
% the current cell.  Solution: use an additional, global variable
% \@lilabel.

% THC: This next command is magic to me.  I didn't write it.
\def\@startline{\global\@curtabmar\@nxttabmar\relax
   \global\@curtab\@curtabmar\setbox\@curline\hbox
    {}\@startfield\strut}

% \code@init is run at the beginning of a codebox environment.
\def\code@init{%
  \zeroli%						  producing the first line
  \setlength{\tabbingsep}{1em}%   distance between numbers and code
  % Initialize \@lilabel to allow a pageref \label cmd at the beginning
  % of the codebox
  \global\let\@lilabel\@currentlabel
  \def\@currentlabel{\@lilabel}%
}

% When we make a codebox, we save the code part into a box before
% printing it.  We do not actually print the code until we know how many
% line numbers there are.
\newsavebox{\savecode}

% The \ifprocname command tells us whether this procedure has been
% given a name yet.
\newif\ifprocname\procnamefalse

% Assume that the width of the codebox is the width of the text, minus
% the width of 2 digits.  We'll correct for that later.
\newlength{\codeboxwidth}
\setlength{\codeboxwidth}{\linewidth} % Thanks, David Etherington!
\addtolength{\codeboxwidth}{-2\digitwidth}

% The "codebox" environment produces an unbreakable section of code
\newenvironment{codebox}{%
\global\procnamefalse%            this proc hasn't been given a name yet
\code@init%                       set up for first line
\begin{lrbox}{\savecode}%         save the code into a box
\begin{minipage}[t]{\codeboxwidth}%  it'll be a minipage
% Set up the tab stops
\def\codeindent{\textbf{else} }%
\begin{tabbing}%
99\=\codeindent\=\codeindent\=\codeindent\=\codeindent\=\codeindent\=\codeindent\=\codeindent\=codeindent\=codeindent\=\+\kill%
}{%
% Here's what's run at the end of a codebox environment.  Start by
% making sure that we have ended at indent level 0.  Otherwise, print a
% warning.
\ifnum\value{indent}=0\else\typeout{Warning: Indentation ends at level \theindent\space in codebox on page \thepage.}\fi%
\end{tabbing}\end{minipage}\end{lrbox}%
\addtolength{\topsep}{0.5ex}%     for the following trivlist
\begin{trivlist}\item\parindent=0pt%
% If there was a procedure name given, print it now but with a little
% space below, and disallow a page break after the procedure name.
\@nobreaktrue%
\ifprocname\saveprocname\rule[-1.25ex]{0pt}{0pt}\\ \fi%
% Put in the right amount of space, depending on whether we reached
% double digits in the line numbers.
\ifnum\value{codelinenumber}>9\hspace*{2\digitwidth}\else\hspace*{1\digitwidth}\fi%
% Now print the code
\usebox{\savecode}\end{trivlist}%
\addtolength{\topsep}{-0.5ex}\global\procnamefalse}

% Use the \Procname macro to give the name of the procedure.
\newcommand{\Procname}[1]{\global\def\saveprocname{#1}\global\procnametrue}

\newcounter{thisindent}			% counter for recursive indenting code
\newcommand{\Indent}{\setcounter{thisindent}{\value{indent}}\putindents}
% \putindents is a recursive macro that indents a number of times given
% by the counter thisindent.
\newcommand{\putindents}{\ifnum\value{thisindent}>0\>\addtocounter{thisindent}{-1}\putindents\fi}

% For typesetting any keyword in the main text.
\newcommand{\kw}[1]{\textbf{#1}}

% Override the 'gets' symbol.
\def\gets{\mathrel{\hspace{1pt}=\hspace{1pt}}}
\newcommand{\isequal}{\mathrel{\scalebox{0.8}[1]{=}\hspace*{1pt}\scalebox{0.8}[1]{=}}}

% All of our favorite keywords.
\newcommand{\For}{\textbf{for} }
\newcommand{\To}{\ifmmode\ \textrm{\textbf{to}}\ \else\textbf{to}\ \fi}
\newcommand{\By}{\ifmmode\ \textrm{\textbf{by}}\ \else\textbf{by}\ \fi}
\newcommand{\Downto}{\ifmmode\ \textrm{\textbf{downto}}\ \else\textbf{downto}\ \fi}
\newcommand{\While}{\textbf{while} }
\newcommand{\Repeat}{\textbf{repeat}\>\addtocounter{indent}{1}}
\newcommand{\Until}{\kill\addtocounter{indent}{-1}\liprint\textbf{until} }
\newcommand{\If}{\textbf{if} }
\newcommand{\Then}{\>\addtocounter{indent}{1}}
\newcommand{\Else}{\kill\addtocounter{indent}{-1}\liprint\textbf{else}\>\addtocounter{indent}{1}}
\newcommand{\End}{\addtocounter{indent}{-1}}
\newcommand{\ElseIf}{\kill\addtocounter{indent}{-1}\liprint\textbf{elseif} }
\newcommand{\ElseNoIf}{\kill\addtocounter{indent}{-1}\liprint\textbf{else} \addtocounter{indent}{1}}
\newcommand{\Do}{\>\addtocounter{indent}{1}}
\newcommand{\Return}{\textbf{return} }
\newcommand{\CommentSymbol}{\texttt{\textbf{/\hspace*{-0.3em}/}}}
\newcommand{\Comment}{\CommentSymbol\ }
\newcommand{\RComment}{\`\CommentSymbol\ }
\newcommand{\Goto}{\textbf{goto} }
\newcommand{\Error}{\textbf{error} } % optionally followed by string argument
\newcommand{\EndTest}{\textbf{:}}
\newcommand{\Spawn}{\ifmmode\textbf{spawn}\ \else\textbf{spawn} \fi}
\newcommand{\Sync}{\textbf{sync}}
\newcommand{\Parfor}{\textbf{parallel for} }

% Indent the next line one level more
\newcommand{\Indentmore}{\addtocounter{indent}{1}}

\newif\ifnumberedline
\numberedlinetrue

% The \li command starts a new numbered line.
\newcommand{\li}{\global\numberedlinetrue%
\iffirstcodeline\global\firstcodelinefalse\else\\ \fi
\stepcounter{codelinenumber}%
\liprint}

% The \lispace command starts a new numbered line with a little extra
% space above, given by the argument.
\newcommand{\lispace}[1]{\iffirstcodeline\global\firstcodelinefalse\else\\[#1] \fi
\stepcounter{codelinenumber}%
\liprint}

% \liprint actually prints the line number and sets up the indentation.
\newcommand{\liprint}{\protected@xdef\@lilabel{\thecodelinenumber}%
\ifnumberedline\thecodelinenumber\fi\'\Indent%
}

\providecommand{\numref}[1]{%
  \@ifundefined{r@#1}{000}{%
    \expandafter\expandafter\expandafter\@firstoftwo
    \csname r@#1\endcsname
  }%
}

% \setlinenumber sets the line number to its argument
\newcommand{\setlinenumber}[1]{\setcounter{codelinenumber}{\numref{#1}}%
\addtocounter{codelinenumber}{-1}}
% \setlinenumberplus sets the line number to its first argument plus its
% second argument.
\newcommand{\setlinenumberplus}[2]{\setcounter{codelinenumber}{\numref{#1}}%
\addtocounter{codelinenumber}{-1}\addtocounter{codelinenumber}{#2}}

% The \zi command starts a new unnumbered line.
\newcommand{\zi}{\global\numberedlinefalse%
\iffirstcodeline\global\firstcodelinefalse\else\\ \fi
\liprint}

% Temporarily make all lines indented so that they start at the end of
% a given text.
\newcommand{\Startalign}[1]{\\ \pushtabs\FakeIndent#1\=\kill}
\newcommand{\Stopalign}{\poptabs}
\newcommand{\FakeIndent}{\setcounter{thisindent}{\value{indent}}\putfakeindents}
\newcommand{\putfakeindents}{\ifnum\value{thisindent}>0\textbf{else }\addtocounter{thisindent}{-1}\putfakeindents\fi}

\endinput