package slangc.parser;

/**
 * Represents a moving point within a sourceFile file, i.e. the point currently being scanned.
 * This is held in it's own class to make it easier for the scanner to be modified/reimplemented.
 * 
 * @author Zak
 *
 */
public final class SourceWalker {
	private Source source;
	private int index, line, character;

	public SourceWalker(Source source, int index, int line, int character) {
		reset(source, index, line, character);
	}
	
	public SourceWalker(Source source) {
		reset(source);
	}
	
	public SourceWalker clone() {
		return new SourceWalker(source, index, line, character);
	}
	
	public SourcePosition getPosition() {
		return new SourcePosition(source, index, line, character);
	}
	
	public Source getSource() {
		return source;
	}
	
	public int getIndex() {
		return index;
	}
	
	public int getLineCount() {
		return line;
	}
	
	public int getCharacterCount() {
		return character;
	}

	public void reset(Source source, int index, int line, int character) {
		this.source = source;
		this.index = index;
		this.line = line;
		this.character = character;
	}
	
	public void reset(Source source) {
		reset(source, 0, 1, 1);
	}
	
	public void reset() {
		reset(source);
	}
	
	public boolean isAtEnd() {
		return !source.isIndexWithinBounds(index);
	}
	
	public void advance() {
		if (!isAtEnd()) {
			if (source.getEncoding().isNewline(source.getCharacter(index))) {
				line++;
				character = 1;
			} else {
				character++;
			}
			index++;
		}
	}
	
	public void advance(int numberOfCharacters) {
		for (int i = 0; i < numberOfCharacters; i++) {
			advance();
		}
	}
}