BehaviourWordRule.java

package org.easyb.ui.editor;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.eclipse.jface.text.rules.ICharacterScanner;
import org.eclipse.jface.text.rules.IPredicateRule;
import org.eclipse.jface.text.rules.IToken;
import org.eclipse.jface.text.rules.Token;

public class BehaviourWordRule implements IPredicateRule{
	
	private final IToken token;
	private final Pattern regexPattern;
	private StringBuffer buffer = new StringBuffer();
	private char firstChar;
	
	public BehaviourWordRule(IToken token,String...words){
		this.token = token;
		this.regexPattern = Pattern.compile(buildRegex(words));
		this.firstChar = getFirstCharFromWords(words);
	}
	
	@Override
	public IToken evaluate(ICharacterScanner scanner, boolean resume) {
		return evaluate(scanner);
	}

	@Override
	public IToken getSuccessToken() {
		return token;
	}

	@Override
	public IToken evaluate(ICharacterScanner scanner) {
		int  readNum = scanner.read();
		char c = (char)readNum;
		if(c!=firstChar){
			scanner.unread();
			return Token.UNDEFINED;
		}
		
		buffer.setLength(0);
		buffer.append(c);
		boolean stringStart = false;
		do{			
			if(!stringStart && isStringIdentifier(c)){
				
				//Could be a groovy GString formatted as """blah blah """
				//So iterate over them if necessary
				c=iterateBeginningForDoubleQuotes(scanner,c);
				stringStart = true;
			}else{
				readNum = scanner.read();
				c = (char)readNum;
				buffer.append(c);
			}
			
			//Must of located an end string so try and match 
			//against the regex
			if(stringStart && isStringIdentifier(c)){
				iterateEndForDoubleQuotes(scanner,c);//Get the full string including trailing " for GStrings
				Matcher matcher = regexPattern.matcher(buffer.toString());
				if(matcher.find()){
					return token;
				}else{
					break;
				}
				
			}
			
		}while(readNum != ICharacterScanner.EOF);
		unread(scanner);
		return Token.UNDEFINED;
	}
	
	/**
	 * Used to iterate over the " in the scanner as groovy can 
	 * have """ for multi-line GString. 
	 * If its looking for the starting "
	 * then need to check for an empty string like "" or """""" in which case 
	 * just return a " indicatign the end of the scanning.
	 * @param scanner
	 * @param checkForEmpty
	 * @return
	 */
	private char iterateBeginningForDoubleQuotes(ICharacterScanner scanner,char lastChar){
		
		if(lastChar!='"'){
			lastChar = (char)scanner.read();
			buffer.append(lastChar);
			return lastChar;
		}
		
		int countQuotes = 1;//The last char is a " so start at 1
		while(lastChar=='"'){
			
			lastChar = (char)scanner.read();
			buffer.append(lastChar);
			
			if(lastChar=='"'){
				++countQuotes;
			}
		}
		
		if((countQuotes==2 || countQuotes==6)){
			return '"';//Signifies the end of the scanning
		}
		
		return lastChar;
	}
	
	private char iterateEndForDoubleQuotes(ICharacterScanner scanner,char lastChar){
		
		if(lastChar!='"'){
			return lastChar;
		}
		
		while(lastChar=='"'){
			
		
			lastChar = (char)scanner.read();
			if(lastChar=='"'){
				buffer.append(lastChar);
			}else{
				scanner.unread();
			}
		}
		
		return lastChar;
	}
	
	protected void unread(ICharacterScanner scanner){
		for (int i= buffer.length() - 1; i >= 0; i--){
			scanner.unread();
		}
	}
	
	protected boolean isStringIdentifier(char c){
		return c=='"'||c=='\''||c=='/';
	}
	
	protected String buildRegex(String[] words){
		StringBuilder builder = new StringBuilder();
		
		builder.append("^\\s*");
		for(String word:words){
			builder.append(word).append("\\s*");
		}
		//builder.append("\\s*[\"|'|\\/|].*[\"|'|\\/|]");
		builder.append("[\"|'|\\/].*[\"|'|\\/]");
		/*TODO do not match when "" as invalid,regex below is nearly there
		 * ^\s*scenario\s*((?!"{2}).)("{3}|"{1}|'|\/)[^"].*((?!"{2}).)("{3}|"{1}|'|\/)$"*/
		//builder.append("\\s*((?!\"{2}).)(\"{3}|\"{1}|'|\\/)[^\"].*((?!\"{2}).)(\"{3}|\"{1}|'|\\/)$");
		//builder.append("\\s*(\"{3}|\"{1}|'|\\/).*(\"{3}|\"{1}|'|\\/)$");
		return builder.toString();
	}
	
	protected char getFirstCharFromWords(String[] words){
		if(words.length==0){
			return 0;
		}
		
		return words[0].charAt(0);
	}
}