net.amygdalum.util.text.linkeddawg.LinkedCharDawg Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of compilerutils Show documentation
Utility classes needed for search and compiler applications
The newest version!
package net.amygdalum.util.text.linkeddawg;

import java.util.Iterator;
import java.util.NoSuchElementException;

import net.amygdalum.util.text.CharAutomaton;
import net.amygdalum.util.text.CharDawg;
import net.amygdalum.util.text.CharNavigator;
import net.amygdalum.util.text.CharNode;

/**
 * A LinkedCharWordGraph is a Directed Acyclic Word Graph based on characters.
 * It has following properties: - acyclic (no back links, no support links) -
 * each node may be reached by one multiple other nodes (i.e. not a tree)
 * 
 * @param  the type of attachment storable in each graph node
 */
public class LinkedCharDawg implements CharDawg {

	private CharNode root;

	public LinkedCharDawg(CharNode root) {
		this.root = root;
	}

	@Override
	public CharAutomaton cursor() {
		return new Cursor<>(root);
	}

	@Override
	public boolean contains(char[] chars) {
		CharNode node = root;
		for (int i = 0; i < chars.length; i++) {
			char c = chars[i];
			node = node.nextNode(c);
			if (node == null) {
				return false;
			}
		}
		return true;
	}

	@Override
	public T find(char[] chars) {
		CharNode node = root;
		for (int i = 0; i < chars.length; i++) {
			char c = chars[i];
			node = node.nextNode(c);
			if (node == null) {
				return null;
			}
		}
		return node.getAttached();
	}

	@Override
	public CharNavigator navigator() {
		return new LinkedCharNavigator<>(root);
	}

	private static class Cursor implements CharAutomaton {

		private CharNode current;
		private CharNode root;
		private AttachmentIterator iterator;

		public Cursor(CharNode root) {
			this.root = root;
			this.current = root;
			this.iterator = new AttachmentIterator<>();
		}

		@Override
		public Iterator iterator() {
			iterator.init(current);
			return iterator;
		}

		@Override
		public void reset() {
			this.current = root;
		}

		@Override
		public boolean lookahead(char c) {
			return current.nextNode(c) != null;
		}

		@Override
		public boolean accept(char c) {
			CharNode next = current.nextNode(c);
			if (next == null) {
				return false;
			}
			current = next;
			return true;
		}

		@Override
		public boolean hasAttachments() {
			return current != null
				&& current.getAttached() != null;
		}

	}

	private static class AttachmentIterator implements Iterator {

		private CharNode current;

		public void init(CharNode current) {
			this.current = current;
		}

		@Override
		public boolean hasNext() {
			return current != null
				&& current.getAttached() != null;
		}

		@Override
		public S next() {
			if (current != null) {
				S attached = current.getAttached();
				current = null;
				if (attached != null) {
					return attached;
				}
			}
			throw new NoSuchElementException();
		}

		@Override
		public void remove() {
			throw new UnsupportedOperationException();
		}

	}
}