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WOOL is a simple, powerful dialogue framework for creating virtual agent conversations.
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/*
 * Copyright 2019 Roessingh Research and Development.
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a 
 * copy of this software and associated documentation files (the "Software"), 
 * to deal in the Software without restriction, including without limitation 
 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 
 * and/or sell copies of the Software, and to permit persons to whom the 
 * Software is furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
 * DEALINGS IN THE SOFTWARE.
 */

package nl.rrd.wool.parser;

import java.util.List;

import nl.rrd.wool.exception.LineNumberParseException;
import nl.rrd.wool.model.command.WoolActionCommand;
import nl.rrd.wool.model.command.WoolCommand;
import nl.rrd.wool.model.command.WoolIfCommand;
import nl.rrd.wool.model.command.WoolInputCommand;
import nl.rrd.wool.model.command.WoolSetCommand;
import nl.rrd.wool.utils.CurrentIterator;

public class WoolCommandParser {
	private List validCommands;
	private WoolNodeState nodeState;
	
	public WoolCommandParser(List validCommands,
			WoolNodeState nodeState) {
		this.validCommands = validCommands;
		this.nodeState = nodeState;
	}

	/**
	 * Reads the command name from the start of a command. The specified
	 * iterator should be positioned at the command start token. When this
	 * method returns, it will be positioned at the token with the command name.
	 * This method does not validate the command name.
	 * 
	 * @param tokens the tokens
	 * @return the command name
	 * @throws LineNumberParseException if a parsing error occurs
	 */
	public String readCommandName(CurrentIterator tokens)
			throws LineNumberParseException {
		WoolBodyToken startToken = tokens.getCurrent();
		tokens.moveNext();
		WoolBodyToken.skipWhitespace(tokens);
		WoolBodyToken token = tokens.getCurrent();
		return getCommandName(startToken, token);
	}
	
	/**
	 * Parses a command from the command name. The specified iterator should be
	 * positioned at the command name token. When this method returns it will be
	 * positioned after the command end token. This method can be called after
	 * {@link #readCommandName(CurrentIterator) readCommandName()}. This method
	 * validates the command name.
	 * 
	 * @param startToken the command start token
	 * @param tokens the tokens
	 * @return the command
	 * @throws LineNumberParseException if a parsing error occurs
	 */
	public WoolCommand parseFromName(WoolBodyToken startToken,
			CurrentIterator tokens)
			throws LineNumberParseException {
		WoolBodyToken token = tokens.getCurrent();
		String name = getCommandName(startToken, token);
		if (!validCommands.contains(name)) {
			throw new LineNumberParseException("Unexpected command: " + name,
					token.getLineNum(), token.getColNum());
		}
		switch (name) {
		case "action":
			return WoolActionCommand.parse(startToken, tokens, nodeState);
		case "if":
			return WoolIfCommand.parse(startToken, tokens, nodeState);
		case "input":
			return WoolInputCommand.parse(startToken, tokens, nodeState);
		case "set":
			return WoolSetCommand.parse(startToken, tokens, nodeState);
		default:
			throw new LineNumberParseException("Unknown command: " + name,
					token.getLineNum(), token.getColNum());
		}
	}
	
	/**
	 * Parses a command from the start token. The specified iterator should be
	 * positioned at the command start token. When this method returns it will
	 * be positioned after the command end token. This method cannot be called
	 * after {@link #readCommandName(CurrentIterator) readCommandName()}. This
	 * method validates the command name.
	 * 
	 * @param tokens the tokens
	 * @return the command
	 * @throws LineNumberParseException if a parsing error occurs
	 */
	public WoolCommand parseFromStart(CurrentIterator tokens)
			throws LineNumberParseException {
		WoolBodyToken startToken = tokens.getCurrent();
		tokens.moveNext();
		WoolBodyToken.skipWhitespace(tokens);
		return parseFromName(startToken, tokens);
	}
	
	/**
	 * Tries to read the command name from the specified name token. This should
	 * be the first non-whitespace token after the command start token. It may
	 * be null.
	 * 
	 * @param startToken the start token
	 * @param nameToken the name token or null
	 * @return the command name
	 * @throws LineNumberParseException if the command name can't be read
	 */
	private String getCommandName(WoolBodyToken startToken,
			WoolBodyToken nameToken) throws LineNumberParseException {
		if (nameToken == null) {
			throw new LineNumberParseException("Command not terminated",
					startToken.getLineNum(), startToken.getColNum());
		}
		if (nameToken.getType() != WoolBodyToken.Type.TEXT) {
			throw new LineNumberParseException(
					"Expected command name, found token: " +
					nameToken.getType(), nameToken.getLineNum(),
					nameToken.getColNum());
		}
		String name = nameToken.getText().trim();
		String[] split = name.split("\\s+", 2);
		return split[0];
	}
}