IDocument based implementation of
+ * CharacterIterator and CharSequence. Note that
+ * the supplied document is not copied; if the document is modified during the
+ * lifetime of a DocumentCharacterIterator, the methods
+ * returning document content may not always return the same values. Also, if
+ * accessing the document fails with a {@link BadLocationException}, any of
+ * CharacterIterator methods as well as charAtmay
+ * return {@link CharacterIterator#DONE}.
+ *
+ * @since 3.0
+ */
+public class DocumentCharacterIterator implements CharacterIterator, CharSequence {
+
+ private int fIndex= -1;
+ private final IDocument fDocument;
+ private final int fFirst;
+ private final int fLast;
+
+ private void invariant() {
+ Assert.isTrue(fIndex >= fFirst);
+ Assert.isTrue(fIndex <= fLast);
+ }
+
+ /**
+ * Creates an iterator for the entire document.
+ *
+ * @param document the document backing this iterator
+ * @throws BadLocationException if the indices are out of bounds
+ */
+ public DocumentCharacterIterator(IDocument document) throws BadLocationException {
+ this(document, 0);
+ }
+
+ /**
+ * Creates an iterator, starting at offset first.
+ *
+ * @param document the document backing this iterator
+ * @param first the first character to consider
+ * @throws BadLocationException if the indices are out of bounds
+ */
+ public DocumentCharacterIterator(IDocument document, int first) throws BadLocationException {
+ this(document, first, document.getLength());
+ }
+
+ /**
+ * Creates an iterator for the document contents from first (inclusive) to
+ * last (exclusive).
+ *
+ * @param document the document backing this iterator
+ * @param first the first character to consider
+ * @param last the last character index to consider
+ * @throws BadLocationException if the indices are out of bounds
+ */
+ public DocumentCharacterIterator(IDocument document, int first, int last) throws BadLocationException {
+ if (document == null)
+ throw new NullPointerException();
+ if (first < 0 || first > last)
+ throw new BadLocationException();
+ if (last > document.getLength()) {
+ throw new BadLocationException();
+ }
+ fDocument= document;
+ fFirst= first;
+ fLast= last;
+ fIndex= first;
+ invariant();
+ }
+
+ /*
+ * @see java.text.CharacterIterator#first()
+ */
+ public char first() {
+ return setIndex(getBeginIndex());
+ }
+
+ /*
+ * @see java.text.CharacterIterator#last()
+ */
+ public char last() {
+ if (fFirst == fLast)
+ return setIndex(getEndIndex());
+ else
+ return setIndex(getEndIndex() - 1);
+ }
+
+ /*
+ * @see java.text.CharacterIterator#current()
+ */
+ public char current() {
+ if (fIndex >= fFirst && fIndex < fLast)
+ try {
+ return fDocument.getChar(fIndex);
+ } catch (BadLocationException e) {
+ // ignore
+ }
+ return DONE;
+ }
+
+ /*
+ * @see java.text.CharacterIterator#next()
+ */
+ public char next() {
+ return setIndex(Math.min(fIndex + 1, getEndIndex()));
+ }
+
+ /*
+ * @see java.text.CharacterIterator#previous()
+ */
+ public char previous() {
+ if (fIndex > getBeginIndex()) {
+ return setIndex(fIndex - 1);
+ } else {
+ return DONE;
+ }
+ }
+
+ /*
+ * @see java.text.CharacterIterator#setIndex(int)
+ */
+ public char setIndex(int position) {
+ if (position >= getBeginIndex() && position <= getEndIndex())
+ fIndex= position;
+ else
+ throw new IllegalArgumentException();
+
+ invariant();
+ return current();
+ }
+
+ /*
+ * @see java.text.CharacterIterator#getBeginIndex()
+ */
+ public int getBeginIndex() {
+ return fFirst;
+ }
+
+ /*
+ * @see java.text.CharacterIterator#getEndIndex()
+ */
+ public int getEndIndex() {
+ return fLast;
+ }
+
+ /*
+ * @see java.text.CharacterIterator#getIndex()
+ */
+ public int getIndex() {
+ return fIndex;
+ }
+
+ /*
+ * @see java.text.CharacterIterator#clone()
+ */
+ @Override
+ public Object clone() {
+ try {
+ return super.clone();
+ } catch (CloneNotSupportedException e) {
+ throw new InternalError();
+ }
+ }
+
+ /*
+ * @see java.lang.CharSequence#length()
+ */
+ public int length() {
+ return getEndIndex() - getBeginIndex();
+ }
+
+ /**
+ * {@inheritDoc}
+ * + * Note that, if the document is modified concurrently, this method may + * return {@link CharacterIterator#DONE} if a {@link BadLocationException} + * was thrown when accessing the backing document. + *
+ * + * @param index {@inheritDoc} + * @return {@inheritDoc} + */ + public char charAt(int index) { + if (index >= 0 && index < length()) + try { + return fDocument.getChar(getBeginIndex() + index); + } catch (BadLocationException e) { + // ignore and return DONE + return DONE; + } + else + throw new IndexOutOfBoundsException(); + } + + /* + * @see java.lang.CharSequence#subSequence(int, int) + */ + public CharSequence subSequence(int start, int end) { + if (start < 0) + throw new IndexOutOfBoundsException(); + if (end < start) + throw new IndexOutOfBoundsException(); + if (end > length()) + throw new IndexOutOfBoundsException(); + try { + return new DocumentCharacterIterator(fDocument, getBeginIndex() + start, getBeginIndex() + end); + } catch (BadLocationException ex) { + throw new IndexOutOfBoundsException(); + } + } +}