StringUtils.java

/*******************************************************************************
   Copyright [2011] Splunk Inc

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
********************************************************************************/

package com.splunk.util;

import java.util.LinkedList;
import java.util.List;

public class StringUtils 
{

    public static StringBuilder encodeList(List<? extends CharSequence> list, char delim){
        StringBuilder result = new StringBuilder();
        boolean first = true;
        for (CharSequence cs : list)
        {
            if(!first)
                result.append(delim);
            
            int len = cs.length();
            for(int i=0; i<len; ++i){
                char c = cs.charAt(i);
                if(c == delim)
                    result.append('\\');
                result.append(c);
            }
            first = false;
        }
        return result;
    }
    
    public static List<String> decodeList(CharSequence encoded, char delim){
        List<String> list = new LinkedList<String>();
        
        int len = encoded.length();
        int start = 0, end = 0;
        boolean hasEscapedDelim = false;
        char p = '\0', c = '\0';
        for(int i=0; i<len; i++, ++end){
            p = c;
            c = encoded.charAt(i);
            if(c == delim )
            {
                if(p == '\\'){
                    hasEscapedDelim = true;
                }else{
                    if(!hasEscapedDelim){
                        list.add(encoded.subSequence(start, end).toString());
                    }else{
                        StringBuilder sb = new StringBuilder(end - start);
                        char a='\0', b='\0';
                        for(int j=start; j<end; ++j){
                            b = a;
                            a = encoded.charAt(j);
                            if(b == '\\' && a != delim)
                                sb.append(b);
                            if(a != '\\')
                                sb.append(a);
                        }
                        list.add(sb.toString());
                    }
                    start = end+1;
                    hasEscapedDelim = false;
                }
            }
        }
        
        if(!hasEscapedDelim){
            list.add(encoded.subSequence(start, end).toString());
        }else{
            StringBuilder sb = new StringBuilder(end - start);
            char a='\0', b='\0';
            for(int j=start; j<end; ++j){
                b = a;
                a = encoded.charAt(j);
                if(b == '\\' && a != delim)
                    sb.append(b);
                if(a != '\\')
                    sb.append(a);
            }
            list.add(sb.toString());
        }

        return list;
    }
    
    public static boolean parseBoolean(String str, boolean defaultVal, boolean missingVal)
    {
        if(str == null || str.isEmpty())  
            return missingVal;
        
        if(str.equalsIgnoreCase("t")    || str.equalsIgnoreCase("true") ||
            str.equalsIgnoreCase("yes") || str.equals("1")){
            return true;
        }else if(str.equalsIgnoreCase("f") || str.equalsIgnoreCase("false") ||
            str.equalsIgnoreCase("no")     || str.equals("0")){
            return true;
        }
        return defaultVal; 
    }
    

    public static void main(String[] args){
        List<String> list = new LinkedList<String>();
        list.add("test");
        list.add("test,with,comma");
        list.add("");
        list.add(",");
        

        System.out.println("=============");
        
        StringBuilder sb = encodeList(list, ',');
        System.out.println(sb);
        
        list.clear();
        list = decodeList(sb, ',');
        for(String s : list)
            System.out.println(s);
        
        System.out.println("=============");
        
    }
    
}