core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/corext/textmanipulation/TextUtil.java

package org.eclipse.cdt.internal.corext.textmanipulation;

/*
 * (c) Copyright IBM Corp. 2000, 2001.
 * All Rights Reserved.
 */
 
import org.eclipse.jface.util.Assert;


public class TextUtil {

	/**
	 * Returns the length of the string desribed by <code>start</code> and 
	 * <code>end</code>.
	 *
	 * @param start the start position. The position is inclusive
	 * @param end the end position. The position is inclusive
	 * @return the length of the string desribed by <code>start</code> and
	 *  <code>end</code>
	 */
	public static int getLength(int start, int end) {
		return end - start + 1;
	}

	/**
	 * Returns the indent of the given line.
	 * @param line the text line
	 * @param tabWidth the width of the '\t' character.
	 */
	public static int getIndent(String line, int tabWidth) {
		int result= 0;
		int blanks= 0;
		int size= line.length();
		for (int i= 0; i < size; i++) {
			char c= line.charAt(i);
			switch (c) {
				case '\t':
					result++;
					blanks= 0;
					break;
				case	' ':
					blanks++;
					if (blanks == tabWidth) {
						result++;
						blanks= 0;
					}
					break;
				default:
					return result;
			}
		}
		return result;
	}
	
	/**
	 * Removes the given number of idents from the line and returns a new
	 * copy of the line. Asserts that the given line has the requested
	 * number of indents.
	 */
	public static String removeIndent(int numberOfIndents, String line, int tabWidth) {
		if (numberOfIndents <= 0)
			return new String(line);
			
		int start= 0;
		int indents= 0;
		int blanks= 0;
		int size= line.length();
		for (int i= 0; i < size; i++) {
			char c= line.charAt(i);
			switch (c) {
				case '\t':
					indents++;
					blanks= 0;
					break;
				case ' ':
					blanks++;
					if (blanks == tabWidth) {
						indents++;
						blanks= 0;
					}
					break;
				default:
					Assert.isTrue(false, "Line does not have requested number of indents"); //$NON-NLS-1$
			}
			if (indents == numberOfIndents) {
				start= i + 1;
				break;
			}	
		}
		if (start == size)
			return ""; //$NON-NLS-1$
		else
			return line.substring(start);
	}
	
	/**
	 * Removes any leading indents from the given string.
	 */
	public static String removeLeadingIndents(String line, int tabWidth) {
		int indents= getIndent(line, tabWidth);
		return removeIndent(indents, line, tabWidth);
	}
	 
	/**
	 * Creates a string that consists of the given number of tab characters.
	 */
	public static String createIndentString(int indent) {
		StringBuffer result= new StringBuffer();
		for (int i= 0; i < indent; i++) {
			result.append('\t');
		}
		return result.toString();
	} 
	
	/**
	 * Removes any leading white spaces from the given string.
	 * The method returns a new string.
	 */
	public static String removeLeadingWhiteSpaces(String line) {
		int size= line.length();
		int start= 0;
		for (int i= 0; i < size; i++) {
			char c= line.charAt(i);
			if (c != '\t' && c != ' ') {
				start= i;
				break;
			}
		}
		return line.substring(start);
	}
	
	/**
	 * Returns <code>true</code> if the given string consists only of
	 * white spaces (e.g. space and '\t'). If the string is empty,
	 * <code>true</code> is returned.
	 */
	public static boolean containsOnlyWhiteSpaces(String line) {
		int size= line.length();
		for (int i= 0; i < size; i++) {
			char c= line.charAt(i);
			if (c != '\t' && c != ' ')
				return false;
		}
		return true;
	}	
}