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diff --git a/Master/texmf-dist/doc/latex/cweb-latex/examples/wcltx.w b/Master/texmf-dist/doc/latex/cweb-latex/examples/wcltx.w new file mode 100644 index 00000000000..4b82bd04f65 --- /dev/null +++ b/Master/texmf-dist/doc/latex/cweb-latex/examples/wcltx.w @@ -0,0 +1,327 @@ +% $Id: wcltx.w,v 1.4 1995/08/29 17:27:57 schrod Exp $ +%------------------------------------------------------------ + +% +% wc: An example of CWEB by Silvio Levy and Donald E. Knuth +% +% [LaTeX] +% (history at end) + + +%% -js: +%% should rework it: ANSI C compliance, POSIX.2 compliant option +%% parsing with getopt(), including *all* required header files (ie, +%% POSIX.1 compliance), using POSIX return codes and types, etc. + + + +\documentclass{cweb} + +\usepackage{rcs} + + +% +% some tags for this document +% +\def\CEE/{C\spacefactor 1000 } +\def\cweb{{\tt CWEB\/}} +\def\SPARC{SPARC\-\kern.1em station} +\def\UNIX/{{\small UNIX\/}} +\def\wc{{\tt wc\/}} +\def\WEB{{\tt WEB\/}} + +\hfuzz=0.5pt + + + + +\begin{document} + + + +\title{Counting words} +\author{Silvio Levy\and Donald E. Knuth} +\begingroup +\def\thefootnote{\hbox{$^*$}} +\footnotetext[0]{\LaTeX{} markup by Joachim Schrod.} +\endgroup +\RCSdate $Date: 1995/08/29 17:27:57 $ + +\maketitle + +% not very interesting, only one starred section +% \tableofcontents + + + +@* An example of \cweb{}. This example, based on a program by +Klaus Guntermann and Joachim Schrod~\cite{litprog:schrod:cweb} +presents the ``word count'' program from \UNIX/, rewritten in +\cweb{} to demonstrate literate programming in \CEE/.% + \footnote{% + Incidentally, Klaus Guntermann and Joachim Schrod are now +using this \cweb{} and have stopped the support for their version. +Joachim Schrod contributed the \LaTeX{} style used for the markup of +this document. + } +The level of detail in this document is intentionally high, for +didactic purposes; many of the things spelled out here don't need to +be explained in other programs. + +The purpose of \wc{} is to count lines, words, and/or characters in a +list of files. The number of lines in a file is the number of newline +characters it contains. The number of characters is the file length in bytes. +A ``word'' is a maximal sequence of consecutive characters other than +newline, space, or tab, containing at least one visible ASCII code. +(We assume that the standard ASCII code is in use.) + +@ Most \cweb{} programs share a common structure. It's probably a +good idea to state the overall structure explicitly at the outset, +even though the various parts could all be introduced in unnamed +sections of the code if we wanted to add them piecemeal. + +Here, then, is an overview of the file \texttt{wcltx.c} that is +defined by this \cweb{} program \texttt{wcltx.w}: + +@c +@<Header files to include@>@/ +@<Global variables@>@/ +@<Functions@>@/ +@<The main program@> + +@ We must include the standard I/O definitions, since we want to send +formatted output to |stdout| and |stderr|. + +@<Header files...@>= +#include <stdio.h> + +@ The |status| variable will tell the operating system if the run was +successful or not, and |prog_name| is used in case there's an error message to +be printed. + +@d OK 0 /* |status| code for successful run */ +@d usage_error 1 /* |status| code for improper syntax */ +@d cannot_open_file 2 /* |status| code for file access error */ + +@<Global variables@>= +int status=OK; /* exit status of command, initially |OK| */ +char *prog_name; /* who we are */ + +@ Now we come to the general layout of the |main| function. + +@<The main...@>= +main (argc,argv) + int argc; /* the number of arguments on the \UNIX/ command line */ + char **argv; /* the arguments themselves, an array of strings */ +{ + @<Variables local to |main|@>@; + prog_name=argv[0]; + @<Set up option selection@>; + @<Process all the files@>; + @<Print the grand totals if there were multiple files @>; + exit(status); +} + +@ If the first argument begins with a `\texttt{-}', the user is choosing +the desired counts and specifying the order in which they should be +displayed. Each selection is given by the initial character +(lines, words, or characters). For example, `\texttt{-cl}' would cause +just the number of characters and the number of lines to be printed, +in that order. + +We do not process this string now; we simply remember where it is. + It will be used to control the formatting at output time. + +@<Var...@>= +int file_count; /* how many files there are */ +char *which; /* which counts to print */ + +@ @<Set up o...@>= +which="lwc"; /* if no option is given, print all three values */ +if (argc>1 && *argv[1] == '-') { which=argv[1]+1; argc--; argv++; } +file_count=argc-1; + +@ Now we scan the remaining arguments and try to open a file, if +possible. The file is processed and its statistics are given. +We use a |do|~\dots~|while| loop because we should read from the +standard input if no file name is given. + +@<Process...@>= +argc--; +do@+{ + @<If a file is given, try to open |*(++argv)|; |continue| if unsuccessful@>; + @<Initialize pointers and counters@>; + @<Scan file@>; + @<Write statistics for file@>; + @<Close file@>; + @<Update grand totals@>; /* even if there is only one file */ +}@+while (--argc>0); + +@ Here's the code to open the file. A special trick allows us to +handle input from |stdin| when no name is given. +Recall that the file descriptor to |stdin| is~0; that's what we +use as the default initial value. + +@<Variabl...@>= +int fd=0; /* file descriptor, initialized to |stdin| */ + +@ @d READ_ONLY 0 /* read access code for system |open| routine */ + +@<If a file...@>= +if (file_count>0 && (fd=open(*(++argv),READ_ONLY))<0) { + fprintf (stderr, "%s: cannot open file %s\n", prog_name, *argv); +@.cannot open file@> + status|=cannot_open_file; + file_count--; + continue; +} + +@ @<Close file@>= +close(fd); + +@ We will do some homemade buffering in order to speed things up: Characters +will be read into the |buffer| array before we process them. +To do this we set up appropriate pointers and counters. + +@d buf_size BUFSIZ /* \texttt{stdio.h}'s |BUFSIZ| is chosen for efficiency */ + +@<Var...@>= +char buffer[buf_size]; /* we read the input into this array */ +register char *ptr; /* the first unprocessed character in |buffer| */ +register char *buf_end; /* the first unused position in |buffer| */ +register int c; /* current character, or number of characters just read */ +int in_word; /* are we within a word? */ +long word_count, line_count, char_count; /* number of words, lines, + and characters found in the file so far */ + +@ @<Init...@>= +ptr=buf_end=buffer; line_count=word_count=char_count=0; in_word=0; + +@ The grand totals must be initialized to zero at the beginning of the +program. If we made these variables local to |main|, we would have to +do this initialization explicitly; however, \CEE/'s globals are automatically +zeroed. (Or rather, ``statically zeroed.'') (Get it?) +@^Joke@> +%% -js: The joke would be better if the vars would be static, which +%% they aren't in the C sense... + +@<Global var...@>= +long tot_word_count, tot_line_count, tot_char_count; + /* total number of words, lines, and chars */ + +@ The present section, which does the counting that is \wc{}'s \emph{raison +d'\^etre}, was actually one of the simplest to write. We look at each +character and change state if it begins or ends a word. + +@<Scan...@>= +while (1) { + @<Fill |buffer| if it is empty; |break| at end of file@>; + c=*ptr++; + if (c>' ' && c<0177) { /* visible ASCII codes */ + if (!in_word) {word_count++; in_word=1;} + continue; + } + if (c=='\n') line_count++; + else if (c!=' ' && c!='\t') continue; + in_word=0; /* |c| is newline, space, or tab */ +} + +@ Buffered I/O allows us to count the number of characters almost for free. + +@<Fill |buff...@>= +if (ptr>=buf_end) { + ptr=buffer; c=read(fd,ptr,buf_size); + if (c<=0) break; + char_count+=c; buf_end=buffer+c; +} + +@ It's convenient to output the statistics by defining a new function +|wc_print|; then the same function can be used for the totals. +Additionally we must decide here if we know the name of the file +we have processed or if it was just |stdin|. + +@<Write...@>= +wc_print(which, char_count, word_count, line_count); +if (file_count) printf (" %s\n", *argv); /* not |stdin| */ +else printf ("\n"); /* |stdin| */ + +@ @<Upda...@>= +tot_line_count+=line_count; +tot_word_count+=word_count; +tot_char_count+=char_count; + +@ We might as well improve a bit on \UNIX/'s \wc{} by displaying the +number of files too. + +@<Print the...@>= +if (file_count>1) { + wc_print(which, tot_char_count, tot_word_count, tot_line_count); + printf(" total in %d files\n",file_count); +} + +@ Here now is the function that prints the values according to the +specified options. The calling routine is supposed to supply a +newline. If an invalid option character is found we inform +the user about proper usage of the command. Counts are printed in +8-digit fields so that they will line up in columns. + +@d print_count(n) printf("%8ld",n) + +@<Fun...@>= +wc_print(which, char_count, word_count, line_count) +char *which; /* which counts to print */ +long char_count, word_count, line_count; /* given totals */ +{ + while (*which) + switch (*which++) { + case 'l': print_count(line_count); break; + case 'w': print_count(word_count); break; + case 'c': print_count(char_count); break; + default: if ((status & usage_error)==0) { + fprintf (stderr, "\nUsage: %s [-lwc] [filename ...]\n", prog_name); +@.Usage: ...@> + status|=usage_error; + } + } +} + +@ Incidentally, a test of this program against the system \wc{} +command on a \SPARC\ showed that the ``official'' \wc{} was slightly +slower. Furthermore, although that \wc{} gave an appropriate error +message for the options `\texttt{-abc}', it made no complaints about the +options `\texttt{-labc}'! Dare we suggest that the system routine +might have been +better if its programmer had used a more literate approach? + + + +\bibliographystyle{plain} +\bibliography{wcltx} + + +@ + +\cwebIndexIntro{% + Here is a list of the identifiers used, and where they appear. +Underlined entries indicate the place of definition. Error messages +are also shown. + } + +\end{document} + + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +% +% $Log: wcltx.w,v $ +% Revision 1.4 1995/08/29 17:27:57 schrod +% Recoded to LaTeX2e markup. +% +% Revision 1.3 1993/06/15 14:01:14 schrod +% Renamed document to wcltx, must change \bibliography tag, too. +% +% Revision 1.2 1993/06/15 13:35:12 schrod +% `cweb' is now a style, was an option formerly. +% +% Revision 1.1 1993/04/09 15:00:37 schrod +% Initial revision +% |