Glob.java

/*
 * Glob.java
 *
 * Created on 23 February 2005, 10:37
 */

package org.owasp.webscarab.util;

import java.util.Stack;

/**
 * Utility class for converting a Unix shell style glob to a Java Regular Expression
 * Shameless "stolen" from JEdit, with many thanks.
 *
 * @author  jedit team
 */
public class Glob {
    
    /** has no instance methods */
    private Glob() {
    }
    
    /**
     * Converts a Unix-style glob to a regular expression.
     *
     * ? becomes ., * becomes .*, {aa,bb} becomes (aa|bb).
     * @param glob The glob pattern
     */
    public static String globToRE(String glob) {
        final Object NEG = new Object();
        final Object GROUP = new Object();
        Stack<Object> state = new Stack<Object>();
        
        StringBuffer buf = new StringBuffer();
        boolean backslash = false;
        
        for(int i = 0; i < glob.length(); i++) {
            char c = glob.charAt(i);
            if(backslash) {
                buf.append('\\');
                buf.append(c);
                backslash = false;
                continue;
            }
            
            switch(c) {
                case '\\':
                    backslash = true;
                    break;
                case '?':
                    buf.append('.');
                    break;
                case '.':
                case '+':
                case '(':
                case ')':
                    buf.append('\\');
                    buf.append(c);
                    break;
                case '*':
                    buf.append(".*");
                    break;
                case '|':
                    if(backslash)
                        buf.append("\\|");
                    else
                        buf.append('|');
                    break;
                case '{':
                    buf.append('(');
                    if(i + 1 != glob.length() && glob.charAt(i + 1) == '!') {
                        buf.append('?');
                        state.push(NEG);
                    }
                    else
                        state.push(GROUP);
                    break;
                case ',':
                    if(!state.isEmpty() && state.peek() == GROUP)
                        buf.append('|');
                    else
                        buf.append(',');
                    break;
                case '}':
                    if(!state.isEmpty()) {
                        buf.append(")");
                        if(state.pop() == NEG)
                            buf.append(".*");
                    }
                    else
                        buf.append('}');
                    break;
                default:
                    buf.append(c);
            }
        }
        
        return buf.toString();
    }
    
}