jtulach@1334: * Iterators maintain a current character index, whose valid range is from jtulach@1334: * getBeginIndex() to getEndIndex(); the value getEndIndex() is included to allow jtulach@1334: * handling of zero-length text ranges and for historical reasons. jtulach@1334: * The current index can be retrieved by calling getIndex() and set directly jtulach@1334: * by calling setIndex(), first(), and last(). jtulach@1334: *
jtulach@1334: * The methods previous() and next() are used for iteration. They return DONE if jtulach@1334: * they would move outside the range from getBeginIndex() to getEndIndex() -1, jtulach@1334: * signaling that the iterator has reached the end of the sequence. DONE is jtulach@1334: * also returned by other methods to indicate that the current index is jtulach@1334: * outside this range. jtulach@1334: * jtulach@1334: *
Examples:
jtulach@1334: * jtulach@1334: * Traverse the text from start to finish jtulach@1334: *
jtulach@1334: * public void traverseForward(CharacterIterator iter) {
jtulach@1334: * for(char c = iter.first(); c != CharacterIterator.DONE; c = iter.next()) {
jtulach@1334: * processChar(c);
jtulach@1334: * }
jtulach@1334: * }
jtulach@1334: *
jtulach@1334: *
jtulach@1334: * Traverse the text backwards, from end to start
jtulach@1334: *
jtulach@1334: * public void traverseBackward(CharacterIterator iter) {
jtulach@1334: * for(char c = iter.last(); c != CharacterIterator.DONE; c = iter.previous()) {
jtulach@1334: * processChar(c);
jtulach@1334: * }
jtulach@1334: * }
jtulach@1334: *
jtulach@1334: *
jtulach@1334: * Traverse both forward and backward from a given position in the text.
jtulach@1334: * Calls to notBoundary() in this example represents some
jtulach@1334: * additional stopping criteria.
jtulach@1334: *
jtulach@1334: * public void traverseOut(CharacterIterator iter, int pos) {
jtulach@1334: * for (char c = iter.setIndex(pos);
jtulach@1334: * c != CharacterIterator.DONE && notBoundary(c);
jtulach@1334: * c = iter.next()) {
jtulach@1334: * }
jtulach@1334: * int end = iter.getIndex();
jtulach@1334: * for (char c = iter.setIndex(pos);
jtulach@1334: * c != CharacterIterator.DONE && notBoundary(c);
jtulach@1334: * c = iter.previous()) {
jtulach@1334: * }
jtulach@1334: * int start = iter.getIndex();
jtulach@1334: * processSection(start, end);
jtulach@1334: * }
jtulach@1334: *
jtulach@1334: *
jtulach@1334: * @see StringCharacterIterator
jtulach@1334: * @see AttributedCharacterIterator
jtulach@1334: */
jtulach@1334:
jtulach@1334: public interface CharacterIterator extends Cloneable
jtulach@1334: {
jtulach@1334:
jtulach@1334: /**
jtulach@1334: * Constant that is returned when the iterator has reached either the end
jtulach@1334: * or the beginning of the text. The value is '\\uFFFF', the "not a
jtulach@1334: * character" value which should not occur in any valid Unicode string.
jtulach@1334: */
jtulach@1334: public static final char DONE = '\uFFFF';
jtulach@1334:
jtulach@1334: /**
jtulach@1334: * Sets the position to getBeginIndex() and returns the character at that
jtulach@1334: * position.
jtulach@1334: * @return the first character in the text, or DONE if the text is empty
jtulach@1334: * @see #getBeginIndex()
jtulach@1334: */
jtulach@1334: public char first();
jtulach@1334:
jtulach@1334: /**
jtulach@1334: * Sets the position to getEndIndex()-1 (getEndIndex() if the text is empty)
jtulach@1334: * and returns the character at that position.
jtulach@1334: * @return the last character in the text, or DONE if the text is empty
jtulach@1334: * @see #getEndIndex()
jtulach@1334: */
jtulach@1334: public char last();
jtulach@1334:
jtulach@1334: /**
jtulach@1334: * Gets the character at the current position (as returned by getIndex()).
jtulach@1334: * @return the character at the current position or DONE if the current
jtulach@1334: * position is off the end of the text.
jtulach@1334: * @see #getIndex()
jtulach@1334: */
jtulach@1334: public char current();
jtulach@1334:
jtulach@1334: /**
jtulach@1334: * Increments the iterator's index by one and returns the character
jtulach@1334: * at the new index. If the resulting index is greater or equal
jtulach@1334: * to getEndIndex(), the current index is reset to getEndIndex() and
jtulach@1334: * a value of DONE is returned.
jtulach@1334: * @return the character at the new position or DONE if the new
jtulach@1334: * position is off the end of the text range.
jtulach@1334: */
jtulach@1334: public char next();
jtulach@1334:
jtulach@1334: /**
jtulach@1334: * Decrements the iterator's index by one and returns the character
jtulach@1334: * at the new index. If the current index is getBeginIndex(), the index
jtulach@1334: * remains at getBeginIndex() and a value of DONE is returned.
jtulach@1334: * @return the character at the new position or DONE if the current
jtulach@1334: * position is equal to getBeginIndex().
jtulach@1334: */
jtulach@1334: public char previous();
jtulach@1334:
jtulach@1334: /**
jtulach@1334: * Sets the position to the specified position in the text and returns that
jtulach@1334: * character.
jtulach@1334: * @param position the position within the text. Valid values range from
jtulach@1334: * getBeginIndex() to getEndIndex(). An IllegalArgumentException is thrown
jtulach@1334: * if an invalid value is supplied.
jtulach@1334: * @return the character at the specified position or DONE if the specified position is equal to getEndIndex()
jtulach@1334: */
jtulach@1334: public char setIndex(int position);
jtulach@1334:
jtulach@1334: /**
jtulach@1334: * Returns the start index of the text.
jtulach@1334: * @return the index at which the text begins.
jtulach@1334: */
jtulach@1334: public int getBeginIndex();
jtulach@1334:
jtulach@1334: /**
jtulach@1334: * Returns the end index of the text. This index is the index of the first
jtulach@1334: * character following the end of the text.
jtulach@1334: * @return the index after the last character in the text
jtulach@1334: */
jtulach@1334: public int getEndIndex();
jtulach@1334:
jtulach@1334: /**
jtulach@1334: * Returns the current index.
jtulach@1334: * @return the current index.
jtulach@1334: */
jtulach@1334: public int getIndex();
jtulach@1334:
jtulach@1334: /**
jtulach@1334: * Create a copy of this iterator
jtulach@1334: * @return A copy of this
jtulach@1334: */
jtulach@1334: public Object clone();
jtulach@1334:
jtulach@1334: }