Java String Remove trimIndent(String line, int indentsToRemove, int tabWidth, int indentWidth)

Description

Removes the given number of indents from the line.

License

Open Source License

Declaration

private static String trimIndent(String line, int indentsToRemove, int tabWidth, int indentWidth) 

Method Source Code

//package com.java2s;
/*******************************************************************************
 * Copyright ? 2008, 2013 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:/*from   w ww.  j  av a  2 s .  c o m*/
 * IBM Corporation - initial API and implementation
 *
 *******************************************************************************/

import java.util.Arrays;

public class Main {
    /**
     * Removes the given number of indents from the line. Asserts that the given line 
     * has the requested number of indents. If <code>indentsToRemove <= 0</code>
     * the line is returned.
     * 
     * @since 3.1
     */
    private static String trimIndent(String line, int indentsToRemove, int tabWidth, int indentWidth) {
        if (line == null || indentsToRemove <= 0)
            return line;

        final int spaceEquivalentsToRemove = indentsToRemove * indentWidth;

        int start = 0;
        int spaceEquivalents = 0;
        int size = line.length();
        String prefix = null;
        for (int i = 0; i < size; i++) {
            char c = line.charAt(i);
            if (c == '\t') {
                int remainder = spaceEquivalents % tabWidth;
                spaceEquivalents += tabWidth - remainder;
            } else if (isIndentChar(c)) {
                spaceEquivalents++;
            } else {
                // Assert.isTrue(false, "Line does not have requested number of indents"); //$NON-NLS-1$
                start = i;
                break;
            }
            if (spaceEquivalents == spaceEquivalentsToRemove) {
                start = i + 1;
                break;
            }
            if (spaceEquivalents > spaceEquivalentsToRemove) {
                // can happen if tabSize > indentSize, e.g tabsize==8, indent==4, indentsToRemove==1, line prefixed with one tab
                // this implements the third option
                start = i + 1; // remove the tab
                // and add the missing spaces
                char[] missing = new char[spaceEquivalents - spaceEquivalentsToRemove];
                Arrays.fill(missing, ' ');
                prefix = new String(missing);
                break;
            }
        }
        String trimmed;
        if (start == size)
            trimmed = ""; //$NON-NLS-1$
        else
            trimmed = line.substring(start);

        if (prefix == null)
            return trimmed;
        return prefix + trimmed;
    }

    /**
     * Indent char is a space char but not a line delimiters.
     * <code>== Character.isWhitespace(ch) && ch != '\n' && ch != '\r'</code>
     */
    private static boolean isIndentChar(char ch) {
        return Character.isWhitespace(ch) && !isLineDelimiterChar(ch);
    }

    /**
     * Line delimiter chars are  '\n' and '\r'.
     */
    private static boolean isLineDelimiterChar(char ch) {
        return ch == '\n' || ch == '\r';
    }
}

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