INIParser.java

package greymerk.roguelike.config;


import java.io.BufferedReader;
import java.io.Writer;
import java.util.regex.Matcher;
import java.util.regex.Pattern;


/**
 *	Parses configuration files using
 *	syntax usually associated with INI
 *	files.
 *
 *	That is, key/value pairs are separated
 *	by an equals sign, on their own line,
 *	empty lines and lines that begin with
 *	a number sign are disregarded.
 */
public class INIParser implements ConfigurationParser {


	private static final String comment_regex="^#";
	private static final String line_regex="^([^=]+)=(.*)$";
	
	
	private Pattern line_pattern;
	private Pattern comment_pattern;
	
	
	/**
	 *	Creates a new INIParser.
	 */
	public INIParser () {
	
		line_pattern=Pattern.compile(line_regex);
		comment_pattern=Pattern.compile(comment_regex);
	
	}


	public Configuration Parse (BufferedReader reader) throws Exception {
	
		//	Loop until we end or extract a line
		for (;;) {
		
			//	Get the next line
			String line=reader.readLine();
			
			//	If there's nothing we fail out
			//	at once
			if (line==null) return null;
			
			//	Strip leading/trailing whitespace
			//	from the line
			line=line.trim();
			
			if (
				//	If this line is empty or...
				(line.length()==0) ||
				//	...if this line is a comment, skip
				comment_pattern.matcher(line).find()
			) continue;
			
			//	Attempt to extract configuration
			//	information from this line
			Matcher matcher=line_pattern.matcher(line);
			
			//	Skip this line if it doesn't match
			//	the pattern
			if (!matcher.find()) continue;
			
			//	Extract the key
			String key=matcher.group(1).trim();
			//	If the key is empty, skip
			if (key.length()==0) continue;
			//	Extract the value
			String value=matcher.group(2).trim();
			//	If the value is empty, skip
			if (value.length()==0) continue;
			
			return new Configuration(key,value);
		
		}
	
	}
	
	
	public void Write (Writer writer, Configuration config) throws Exception {
	
		writer.write(config.Key);
		writer.write("=");
		writer.write(config.Value);
		writer.write(System.getProperty("line.separator"));
	
	}


}