Trim.java

package com.github.gist.maxdw;

import java.text.CharacterIterator;
import java.text.StringCharacterIterator;

class Trim {
    /**
     * All characters on both the left side and the right side
     * of the string that appear in the provided characters string
     * argument will be trimmed until a character in string does
     * not appear in the characters string argument (individually
     * for each side).
     *
     * @param string e.g. 'cbabc'
     * @param characters 'cb'
     * @return 'a'
     */
    static String both(String string, String characters) {
        string = Trim.left(string, characters);
        string = Trim.right(string, characters);
        return string;
    }

    /**
     * All characters of the right side of the provided string
     * that appear in the provided characters string argument
     * will be trimmed until a character in string does not
     * appear in the characters string argument.
     *
     * @param string e.g. 'abc'
     * @param characters e.g. 'cb'
     * @return 'a'
     */
    static String right(String string, String characters) {
        CharacterIterator it = new StringCharacterIterator(string);
        int beginIndex = it.getBeginIndex();
        int endIndex = it.getEndIndex();
        it.last();
        do {
            char chr = it.current();
            if (!characters.contains(String.valueOf(chr))) {
                break;
            }
            endIndex--;
        } while (it.previous() != CharacterIterator.DONE);
        return string.substring(beginIndex, endIndex);
    }

    /**
     * All characters of the left side of the provided string
     * that appear in the provided characters string argument
     * will be trimmed until a character in string does not
     * appear in the characters string argument.
     *
     * @param string e.g. 'abc'
     * @param characters 'ba'
     * @return 'a'
     */
    static String left(String string, String characters) {
        CharacterIterator it = new StringCharacterIterator(string);
        int beginIndex = it.getBeginIndex();
        int endIndex = it.getEndIndex();
        do {
            char chr = it.current();
            if (!characters.contains(String.valueOf(chr))) {
                break;
            }
            beginIndex++;
        } while(it.next() != CharacterIterator.DONE);
        return string.substring(beginIndex, endIndex);
    }
}