% pp % Nick James % 21-10-2011
pp copies it's input to stdout, optionally incorporating output of arbitrary programs.
This looks like a simple scripting problem, but I've got a c++ hammer.
When writing documentation using pandoc it is handy to insert mechanically gleaned lumps of text into the document (like this one); ensuring that examples, output, source code or what have you are up to date.
No doubt there are other ways pp could be used.
Windows:
- Unzip pp.zip, put pp.exe somewhere on your path.
Linux
-
flex -o../lex.yy.c ../pp.l
g++ -o pp ../pp.cpp ../lex.yy.c and put pp on your PATH
pp filename
pp preprocesses it's argument file.
This is a matter of copying it's input to stdout, substituting lines beginning with !!PP with the output of the command as executed by the command processor. This incorporates the program output into the contents of the file being written to stdout.
If you need to suppress the last newline in the output of a !!PP cmd, use !!PPS instead.
If you need !!PP starting on column 1 of your output, use !!PPecho !!PP
For file example.txt:
A text file containing a !!PP directive
!!PP echo hello world
!!PPS echo look, no extra newline
Thank you and good bye.
!!PPdate /t
pp example.txt gives us:
A text file containing a !!PP directive
hello world
look, no extra newline
Thank you and good bye.
05/06/2016
-
The results of the command executed are potentially disastrous. Stick to type/cat, grep, sed and echo.
-
The supplied binary may have dll dependencies that mean you have to recompile the source on your machine.
This is essentially a call to yylex(). The lex is as follows:
%{
#include <string>
%}
%option noyywrap
%x GOT_PP
%x GOT_PPS
%%
^!!PP {
BEGIN(GOT_PP);
}
^!!PPS {
BEGIN(GOT_PPS);
}
<GOT_PP>[^\n]* {
/*
we use popen() as output from system()
doesn't turn up where we want it
*/
FILE *pfp = _popen(yytext, "r");
if (pfp != 0)
{
while (!feof(pfp) && !ferror(pfp))
{
int c = fgetc(pfp);
if (c != EOF)
putchar(c);
}
_pclose(pfp);
}
BEGIN(INITIAL);
}
<GOT_PPS>[^\n]* {
/*
we use popen() as output from system()
doesn't turn up where we want it
*/
FILE *pfp = _popen(yytext, "r");
if (pfp != 0)
{
std::string res;
while (!feof(pfp) && !ferror(pfp))
{
int c = fgetc(pfp);
if (c != EOF)
{
char s[2];
s[0] = (char)c;
s[1] = 0;
res.append(s);
}
}
size_t resLen = res.length();
if (resLen > 0 && res[resLen-1] == '\n')
res = res.substr(0, resLen-1);
fprintf(stdout, "%s", res.c_str());
}
_pclose(pfp);
BEGIN(INITIAL);
}
. {
ECHO;
}
flex pp.l
g++ -o pp.exe pp.cpp lex.yy.c
or use gcc\\compile.bat
Produced with:
pp pp.txt.pp > pp.md pandoc --toc -N -t html5 -c devDoc.css -s -o pp.html pp.md 2016-06-05 22:58:55
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