source: trunk/src/org/expeditee/gui/management/ResourceUtil.java@ 1439

package org.expeditee.gui.management;

public class ResourceUtil {
        
        private static final char PATTERN_START_TWO = '{';
        private static final char PATTERN_START_ONE = '$';
        private static final char PATTERN_END = '}';
        private static final char ESCAPE = '\\';

        public static final String CURRENT_FRAMESET_FLAG = "${CURRENT_FRAMESET}";
        public static final String CURRENT_USER = "${CURRENT_USER}";
        
        /**
         * Utility function that transforms a input string to a output string.
         * Any occurances of 'pattern' are replaced with 'replacement'.
         * \ is used as the escape key.
         * @param input The raw input
         * @param pattern The pattern to replace.  
         * This will be prepended by in ${ and appended by } in the input string.
         * @param replacement The replacement content to use.
         * @return The transformed string.
         */
        protected static String substitute(String input, String pattern, String replacement) {          
                StringBuilder outputSB = new StringBuilder();
                StringBuilder inputSB = new StringBuilder(input.replace("\\", "\\\\") + ResourceUtil.ESCAPE);
                StringBuilder patternSB = new StringBuilder();
                boolean inPattern = false;
                boolean patternStartPossible = true;
                
                int index = 0;
                int length = inputSB.length() - 1;
                while (index < length) {
                        char c = inputSB.charAt(index);
                        boolean startingPattern = patternStartPossible && 
                                        c == ResourceUtil.PATTERN_START_TWO &&
                                        outputSB.charAt(outputSB.length() - 1) == ResourceUtil.PATTERN_START_ONE;
                        boolean endingPattern = c == ResourceUtil.PATTERN_END;
                        
                        if (c == ResourceUtil.ESCAPE && !inPattern) {
                                index++;
                                c = inputSB.charAt(index);
                                outputSB.append(c);
                                if (c == PATTERN_START_ONE) {
                                        patternStartPossible = false;
                                }
                        } else if (inPattern && endingPattern) {
                                String patternFound = patternSB.toString();
                                if (("${" + patternFound + "}").equals(pattern)) {
                                        outputSB.append(replacement);
                                } else {
                                        outputSB.append("" + ResourceUtil.PATTERN_START_ONE + ResourceUtil.PATTERN_START_TWO);
                                        outputSB.append(patternFound);
                                        outputSB.append(ResourceUtil.PATTERN_END);
                                }
                                inPattern = false;
                                patternSB = new StringBuilder();
                        } else if (!inPattern && startingPattern) {
                                outputSB.deleteCharAt(outputSB.length() - 1);
                                inPattern = true;
                        } else if (inPattern) {
                                patternSB.append(c);
                        } else {
                                outputSB.append(c);
                                patternStartPossible = true;
                        }
                        
                        index++;
                }
                
                if (patternSB.length() > 0) {
                        outputSB.append("${");
                }
                outputSB.append(patternSB);
                return outputSB.toString();
        }
}