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Rich-text area for JavaFX
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package org.fxmisc.richtext.model;
import java.util.Objects;
import java.util.Optional;
/**
* Base change class for style changes ({@link RichTextChange}) and non-style changes ({@link PlainTextChange})
* in a {@link org.fxmisc.richtext.TextEditingArea}.
*
* @param type of data that was removed and inserted in the {@link org.fxmisc.richtext.TextEditingArea}.
* @param a subclass of TextChange
*/
public abstract class TextChange> {
protected final int position;
protected final S removed;
protected final S inserted;
public TextChange(int position, S removed, S inserted) {
this.position = position;
this.removed = removed;
this.inserted = inserted;
}
/**
* Gets the start position of where the replacement happened
*/
public int getPosition() { return position; };
public S getRemoved() { return removed; }
public S getInserted() { return inserted; }
/**
* Returns a new subclass of {@link TextChange} that makes the {@code inserted} the removed object and
* the {@code removed} the inserted object
*/
public Self invert() { return create(position, inserted, removed); }
/** Returns the position where the removal ends (e.g. {@code position + removedLength())} */
public int getRemovalEnd() { return position + removedLength(); }
/** Returns the position where the inserted ends (e.g. {@code position + insertedLength())} */
public int getInsertionEnd() { return position + insertedLength(); }
/**
* Gets the net length of this change (i.e., {@code insertedLength() - removedLength()})
*/
public int getNetLength() { return insertedLength() - removedLength(); }
protected abstract int removedLength();
protected abstract int insertedLength();
protected abstract S concat(S a, S b);
protected abstract S sub(S s, int from, int to);
protected abstract Self create(int position, S removed, S inserted);
/**
* Returns true if this change is an identity change: applying it does nothing as it removes what it inserts.
* See also {@link java.util.function.Function#identity()}
*/
public final boolean isIdentity() {
return removed.equals(inserted);
}
/**
* Merges this change with the given change, if possible.
* This change is considered to be the former and the given
* change is considered to be the latter.
* Changes can be merged if either
*
* - the latter's start matches the former's added text end; or
* - the latter's removed text end matches the former's added text end.
*
* @param latter change to merge with this change.
* @return a new merged change if changes can be merged,
* {@code null} otherwise.
*/
public Optional mergeWith(Self latter) {
if(latter.position == this.position + this.insertedLength()) {
S removedText = concat(this.removed, latter.removed);
S addedText = concat(this.inserted, latter.inserted);
return Optional.of(create(this.position, removedText, addedText));
} else if(latter.position + latter.removedLength() == this.position + this.insertedLength()) {
if(this.position <= latter.position) {
S addedText = concat(sub(this.inserted, 0, latter.position - this.position), latter.inserted);
return Optional.of(create(this.position, this.removed, addedText));
}
else {
S removedText = concat(sub(latter.removed, 0, this.position - latter.position), this.removed);
return Optional.of(create(latter.position, removedText, latter.inserted));
}
} else {
return Optional.empty();
}
}
@Override
public boolean equals(Object other) {
if(other instanceof TextChange) {
TextChange that = (TextChange) other;
return Objects.equals(this.position, that.position)
&& Objects.equals(this.removed, that.removed )
&& Objects.equals(this.inserted, that.inserted);
} else {
return false;
}
}
@Override
public int hashCode() {
return Objects.hash(position, removed, inserted);
}
@Override
public final String toString() {
return
this.getClass().getSimpleName() + "{\n" +
"\tposition: " + position + "\n" +
"\tremoved: " + removed + "\n" +
"\tinserted: " + inserted + "\n" +
"}";
}
}