/**
* EnTab: replace blanks by tabs and blanks. Transmuted from K&R Software Tools
* book into C. Transmuted again, years later, into Java. Totally rewritten to
* be line-at-a-time instead of char-at-a-time.
*
* @author Ian F. Darwin, http://www.darwinsys.com/
* @version $Id: ch03,v 1.3 2004/05/04 18:03:14 ian Exp $
*/
public class EnTab {
/** The Tabs (tab logic handler) */
protected Tabs tabs;
/**
* Delegate tab spacing information to tabs.
*
* @return
*/
public int getTabSpacing( ) {
return tabs.getTabSpacing( );
}
/**
* Main program: just create an EnTab object, and pass the standard input
* or the named file(s) through it.
*/
public static void main(String[] argv) throws IOException {
EnTab et = new EnTab(8);
if (argv.length == 0) // do standard input
et.entab(
new BufferedReader(new InputStreamReader(System.in)),
System.out);
else
for (int i = 0; i < argv.length; i++) { // do each file
et.entab(
new BufferedReader(new FileReader(argv[i])),
System.out);
}
}
/**
* Constructor: just save the tab values.
*
* @param n
* The number of spaces each tab is to replace.
*/
public EnTab(int n) {
tabs = new Tabs(n);
}
public EnTab( ) {
tabs = new Tabs( );
}
/**
* entab: process one file, replacing blanks with tabs.
*
* @param is A BufferedReader opened to the file to be read.
* @param out a PrintWriter to send the output to.
*/
public void entab(BufferedReader is, PrintWriter out) throws IOException {
String line;
int c, col = 0, newcol;
// main loop: process entire file one line at a time.
while ((line = is.readLine( )) != null) {
out.println(entabLine(line));
}
}
/**
* entab: process one file, replacing blanks with tabs.
*
* @param is A BufferedReader opened to the file to be read.
* @param out A PrintStream to write the output to.
*/
public void entab(BufferedReader is, PrintStream out) throws IOException {
entab(is, new PrintWriter(out));
}
/**
* entabLine: process one line, replacing blanks with tabs.
*
* @param line -
* the string to be processed
*/
public String entabLine(String line) {
int N = line.length( ), outCol = 0;
StringBuffer sb = new StringBuffer( );
char ch;
int consumedSpaces = 0;
for (int inCol = 0; inCol < N; inCol++) {
ch = line.charAt(inCol);
// If we get a space, consume it, don't output it.
// If this takes us to a tab stop, output a tab character.
if (ch == ' ') {
Debug.println("space", "Got space at " + inCol);
if (!tabs.isTabStop(inCol)) {
consumedSpaces++;
} else {
Debug.println("tab", "Got a Tab Stop "+ inCol);
sb.append('\t');
outCol += consumedSpaces;
consumedSpaces = 0;
}
continue;
}
// We're at a non-space; if we're just past a tab stop, we need
// to put the "leftover" spaces back out, since we consumed
// them above.
while (inCol-1 > outCol) {
Debug.println("pad", "Padding space at "+ inCol);
sb.append(' ');
outCol++;
}
// Now we have a plain character to output.
sb.append(ch);
outCol++;
}
// If line ended with trailing (or only!) spaces, preserve them.
for (int i = 0; i < consumedSpaces; i++) {
Debug.println("trail", "Padding space at end # " + i);
sb.append(' ');
}
return sb.toString( );
}
}
The code also has several Debug printouts
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