postprint.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

/*
 *
 * Handles things that must be done after the options are read but before the
 * input files are processed. linespp (lines per page) can be set using the -l
 * option. If it's not positive we calculate a reasonable value using the
 * requested point size - assuming LINESPP lines fit on a page in point size
 * POINTSIZE.
 *
 */

    writerequest(0, stdout);		/* global requests eg. manual feed */
    setencoding(fontencoding);
    fprintf(stdout, "setup\n");

    if ( formsperpage > 1 ) {
	if ( cat(formfile) == FALSE )
	    error(FATAL, "can't read %s", formfile);
	fprintf(stdout, "%d setupforms\n", formsperpage);
    }	/* End if */

    fprintf(stdout, "%s", ENDSETUP);

    if ( linespp <= 0 )
	linespp = LINESPP * POINTSIZE / pointsize;

}   /* End of setup */

/*****************************************************************************/

arguments()

{

/*
 *
 * Makes sure all the non-option command line arguments are processed. If we get
 * here and there aren't any arguments left, or if '-' is one of the input files
 * we'll translate stdin.
 *
 */

    if ( argc < 1 )
	text();
    else {				/* at least one argument is left */
	while ( argc > 0 ) {
	    if ( strcmp(*argv, "-") == 0 )
		fp_in = stdin;
	    else if ( (fp_in = fopen(*argv, "r")) == NULL )
		error(FATAL, "can't open %s", *argv);
	    text();
	    if ( fp_in != stdin )
		fclose(fp_in);
	    argc--;
	    argv++;
	}   /* End while */
    }   /* End else */

}   /* End of arguments */

/*****************************************************************************/

done()

{

/*
 *
 * Finished with all the input files, so mark the end of the pages with a TRAILER
 * comment, make sure the last page prints, and add things like the PAGES comment
 * that can only be determined after all the input files have been read.
 *
 */

    fprintf(stdout, "%s", TRAILER);
    fprintf(stdout, "done\n");
    fprintf(stdout, "%s %s\n", DOCUMENTFONTS, fontname);
    fprintf(stdout, "%s %d\n", PAGES, printed);

}   /* End of done */

/*****************************************************************************/

account()

{

/*
 *
 * Writes an accounting record to *fp_acct provided it's not NULL. Accounting is
 * requested using the -A or -J options.
 *
 */

    if ( fp_acct != NULL )
	fprintf(fp_acct, " print %d\n copies %d\n", printed, copies);

}   /* End of account */

/*****************************************************************************/

text()

{

    int		ch;			/* next input character */

/*
 *
 * Translates *fp_in into PostScript. Intercepts space, tab, backspace, newline,
 * return, and formfeed. Everything else goes to oput(), which handles quoting
 * (if needed) and escapes for nonascii characters if extended is TRUE. The
 * redirect(-1) call forces the initial output to go to /dev/null - so stuff
 * that formfeed() does at the end of each page goes to /dev/null rather than
 * the real output file.
 *
 */

    redirect(-1);			/* get ready for the first page */
    formfeed();				/* force PAGE comment etc. */

    while ( (ch = getc(fp_in)) != EOF )
	switch ( ch ) {
	    case '\n':
		    newline();
		    break;

	    case '\t':
	    case '\b':
	    case ' ':
		    spaces(ch);
		    break;

	    case '\014':
		    formfeed();
		    break;

	    case '\r':
		    if ( crmode == 1 )
			spaces(ch);
		    else if ( crmode == 2 )
			newline();
		    break;

	    default:
		    oput(ch);
		    break;
	}   /* End switch */

    formfeed();				/* next file starts on a new page? */

}   /* End of text */

/*****************************************************************************/

formfeed()

{

/*
 *
 * Called whenever we've finished with the last page and want to get ready for the
 * next one. Also used at the beginning and end of each input file, so we have to
 * be careful about what's done. The first time through (up to the redirect() call)
 * output goes to /dev/null.
 *
 * Adobe now recommends that the showpage operator occur after the page level
 * restore so it can be easily redefined to have side-effects in the printer's VM.
 * Although it seems reasonable I haven't implemented it, because it makes other
 * things, like selectively setting manual feed or choosing an alternate paper
 * tray, clumsy - at least on a per page basis. 
 *
 */

    if ( fp_out == stdout )		/* count the last page */
	printed++;

    endline();				/* print the last line */

    fprintf(fp_out, "cleartomark\n");
    fprintf(fp_out, "showpage\n");
    fprintf(fp_out, "saveobj restore\n");
    fprintf(fp_out, "%s %d %d\n", ENDPAGE, page, printed);

    if ( ungetc(getc(fp_in), fp_in) == EOF )
	redirect(-1);
    else redirect(++page);

    fprintf(fp_out, "%s %d %d\n", PAGE, page, printed+1);
    fprintf(fp_out, "/saveobj save def\n");
    fprintf(fp_out, "mark\n");
    writerequest(printed+1, fp_out);
    fprintf(fp_out, "%d pagesetup\n", printed+1);

    line = 1;

}   /* End of formfeed */

/*****************************************************************************/

newline()

{

/*
 *
 * Called when we've read a newline character. The call to startline() ensures
 * that at least an empty string is on the stack.
 *
 */

    startline();
    endline();				/* print the current line */

    if ( ++line > linespp )		/* done with this page */
	formfeed();

}   /* End of newline */

/*****************************************************************************/

spaces(ch)

    int		ch;			/* next input character */

{

    int		endcol;			/* ending column */
    int		i;			/* final distance - in spaces */

/*
 *
 * Counts consecutive spaces, tabs, and backspaces and figures out where the next
 * string should start. Once that's been done we try to choose an efficient way
 * to output the required number of spaces. The choice is between using procedure
 * l with a single string on the stack and L with several string and column pairs.
 * We usually break even, in terms of the size of the output file, if we need four
 * consecutive spaces. More means using L decreases the size of the file. For now
 * if there are less than 6 consecutive spaces we just add them to the current
 * string, otherwise we end that string, follow it by its starting position, and
 * begin a new one that starts at endcol. Backspacing is always handled this way.
 *
 */

    startline();			/* so col makes sense */
    endcol = col;

    do {
	if ( ch == ' ' )
	    endcol++;
	else if ( ch == '\t' )
	    endcol += tabstops - ((endcol - 1) % tabstops);
	else if ( ch == '\b' )
	    endcol--;
	else if ( ch == '\r' )
	    endcol = 1;
	else break;
    } while ( ch = getc(fp_in) );	/* if ch is 0 we'd quit anyway */

    ungetc(ch, fp_in);			/* wasn't a space, tab, or backspace */

    if ( endcol < 1 )			/* can't move past left edge */
	endcol = 1;

    if ( (i = endcol - col) >= 0 && i < 6 )
	for ( ; i > 0; i-- )
	    oput((int)' ');
    else {
	endstring();
	col = stringstart = endcol;
    }	/* End else */

}   /* End of spaces */

/*****************************************************************************/

startline()

{

/*
 *
 * Called whenever we want to be certain we're ready to start pushing characters
 * into an open string on the stack. If stringcount is positive we've already
 * started, so there's nothing to do. The first string starts in column 1.
 *
 */

    if ( stringcount < 1 ) {
	putc('(', fp_out);
	stringstart = col = 1;
	stringcount = 1;
    }	/* End if */

}   /* End of startline */

/*****************************************************************************/

endstring()

{

/*
 *
 * End the current string and start a new one.
 *
 */

    if ( stringcount > 100 ) {		/* don't put too much on the stack */
	fprintf(fp_out, ")%d LL\n(", stringstart-1);
	stringcount = 2;		/* kludge - don't let endline() use l */
    } else {
	fprintf(fp_out, ")%d(", stringstart-1);
	stringcount++;
    }   /* End else */

}   /* End of endstring */

/*****************************************************************************/

endline()

{

/*
 *
 * Generates a call to the PostScript procedure that processes all the text on
 * the stack - provided stringcount is positive. If one string is on the stack
 * the fast procedure (ie. l) is used to print the line, otherwise the slower
 * one that processes string and column pairs is used.
 *
 */

    if ( stringcount == 1 )
	fprintf(fp_out, ")l\n");
    else if ( stringcount > 1 )
	fprintf(fp_out, ")%d L\n", stringstart-1);

    stringcount = 0;

}   /* End of endline */

/*****************************************************************************/

oput(ch)

    int		ch;			/* next output character */

{

/*
 *
 * Responsible for adding all printing characters from the input file to the
 * open string on top of the stack.
 *
 */

    if ( isascii(ch) && isprint(ch) ) {
	startline();
	if ( ch == '(' || ch == ')' || ch == '\\' )
	    putc('\\', fp_out);
	putc(ch, fp_out);
	col++;
    } else if ( extended == TRUE ) {
	startline();
	fprintf(fp_out, "\\%.3o", ch & 0377);
	col++;
    }	/* End if */

}   /* End of oput */

/*****************************************************************************/

redirect(pg)

    int		pg;			/* next page we're printing */

{

    static FILE	*fp_null = NULL;	/* if output is turned off */

/*
 *
 * If we're not supposed to print page pg, fp_out will be directed to /dev/null,
 * otherwise output goes to stdout.
 *
 */

    if ( pg >= 0 && in_olist(pg) == ON )
	fp_out = stdout;
    else if ( (fp_out = fp_null) == NULL )
	fp_out = fp_null = fopen("/dev/null", "w");

}   /* End of redirect */

/*****************************************************************************/