NSString+HTML.m

//
//  NSString+Koolistov.m
//  Koolistov
//
//  Created by Johan Kool on 13-11-09.
//  Copyright 2009-2011 Koolistov Pte. Ltd. All rights reserved.
//
//  Redistribution and use in source and binary forms, with or without modification, are
//  permitted provided that the following conditions are met:
//
//  * Redistributions of source code must retain the above copyright notice, this list of
//    conditions and the following disclaimer.
//  * Neither the name of KOOLISTOV PTE. LTD. nor the names of its contributors may be used to
//    endorse or promote products derived from this software without specific prior written
//    permission.
//
//  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
//  EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
//  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
//  THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
//  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
//  OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
//  HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
//  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
//  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//


#import "NSString+HTML.h"

@implementation NSString (HTML)

// Method based on code obtained from:
// http://www.thinkmac.co.uk/blog/2005/05/removing-entities-from-html-in-cocoa.html
//

- (NSString *)kv_decodeHTMLCharacterEntities {
    if ([self rangeOfString:@"&"].location == NSNotFound) {
        return self;
    } else {
        NSMutableString *escaped = [NSMutableString stringWithString:self];
        NSArray *codes = [NSArray arrayWithObjects:
                          @" ", @"¡", @"¢", @"£", @"¤", @"¥", @"¦",
                          @"§", @"¨", @"©", @"ª", @"«", @"¬", @"­", @"®",
                          @"¯", @"°", @"±", @"²", @"³", @"´", @"µ",
                          @"¶", @"·", @"¸", @"¹", @"º", @"»", @"¼",
                          @"½", @"¾", @"¿", @"À", @"Á", @"Â",
                          @"Ã", @"Ä", @"Å", @"Æ", @"Ç", @"È",
                          @"É", @"Ê", @"Ë", @"Ì", @"Í", @"Î", @"Ï",
                          @"Ð", @"Ñ", @"Ò", @"Ó", @"Ô", @"Õ", @"Ö",
                          @"×", @"Ø", @"Ù", @"Ú", @"Û", @"Ü", @"Ý",
                          @"Þ", @"ß", @"à", @"á", @"â", @"ã", @"ä",
                          @"å", @"æ", @"ç", @"è", @"é", @"ê", @"ë",
                          @"ì", @"í", @"î", @"ï", @"ð", @"ñ", @"ò",
                          @"ó", @"ô", @"õ", @"ö", @"÷", @"ø", @"ù",
                          @"ú", @"û", @"ü", @"ý", @"þ", @"ÿ", nil];
		
        NSUInteger i, count = [codes count];
		
        // Html
        for (i = 0; i < count; i++) {
            NSRange range = [self rangeOfString:[codes objectAtIndex:i]];
            if (range.location != NSNotFound) {
                [escaped replaceOccurrencesOfString:[codes objectAtIndex:i]
                                         withString:[NSString stringWithFormat:@"%C", @(160 + i).unsignedShortValue]
                                            options:NSLiteralSearch
                                              range:NSMakeRange(0, [escaped length])];
            }
        }
		
        // The following five are not in the 160+ range
		
        // @"&amp;"
        NSRange range = [self rangeOfString:@"&amp;"];
        if (range.location != NSNotFound) {
            [escaped replaceOccurrencesOfString:@"&amp;"
                                     withString:[NSString stringWithFormat:@"%C", @(38).unsignedShortValue]
                                        options:NSLiteralSearch
                                          range:NSMakeRange(0, [escaped length])];
        }
		
        // @"&lt;"
        range = [self rangeOfString:@"&lt;"];
        if (range.location != NSNotFound) {
            [escaped replaceOccurrencesOfString:@"&lt;"
                                     withString:[NSString stringWithFormat:@"%C", @(60).unsignedShortValue]
                                        options:NSLiteralSearch
                                          range:NSMakeRange(0, [escaped length])];
        }
		
        // @"&gt;"
        range = [self rangeOfString:@"&gt;"];
        if (range.location != NSNotFound) {
            [escaped replaceOccurrencesOfString:@"&gt;"
                                     withString:[NSString stringWithFormat:@"%C", @(62).unsignedShortValue]
                                        options:NSLiteralSearch
                                          range:NSMakeRange(0, [escaped length])];
        }
		
        // @"&apos;"
        range = [self rangeOfString:@"&apos;"];
        if (range.location != NSNotFound) {
            [escaped replaceOccurrencesOfString:@"&apos;"
                                     withString:[NSString stringWithFormat:@"%C", @(39).unsignedShortValue]
                                        options:NSLiteralSearch
                                          range:NSMakeRange(0, [escaped length])];
        }
		
        // @"&quot;"
        range = [self rangeOfString:@"&quot;"];
        if (range.location != NSNotFound) {
            [escaped replaceOccurrencesOfString:@"&quot;"
                                     withString:[NSString stringWithFormat:@"%C", @(34).unsignedShortValue]
                                        options:NSLiteralSearch
                                          range:NSMakeRange(0, [escaped length])];
        }
		
        // Decimal & Hex
        NSRange start, finish, searchRange = NSMakeRange(0, [escaped length]);
        i = 0;
		
        while (i < [escaped length]) {
            start = [escaped rangeOfString:@"&#"
                                   options:NSCaseInsensitiveSearch
                                     range:searchRange];
			
            finish = [escaped rangeOfString:@";"
                                    options:NSCaseInsensitiveSearch
                                      range:searchRange];
			
            if (start.location != NSNotFound && finish.location != NSNotFound &&
                finish.location > start.location) {
                NSRange entityRange = NSMakeRange(start.location, (finish.location - start.location) + 1);
                NSString *entity = [escaped substringWithRange:entityRange];
                NSString *value = [entity substringWithRange:NSMakeRange(2, [entity length] - 2)];
				
                [escaped deleteCharactersInRange:entityRange];
				
                if ([value hasPrefix:@"x"]) {
                    unsigned tempInt = 0;
                    NSScanner *scanner = [NSScanner scannerWithString:[value substringFromIndex:1]];
                    [scanner scanHexInt:&tempInt];
                    [escaped insertString:[NSString stringWithFormat:@"%C", @(tempInt).unsignedShortValue] atIndex:entityRange.location];
                } else {
                    [escaped insertString:[NSString stringWithFormat:@"%C", @([value intValue]).unsignedShortValue] atIndex:entityRange.location];
                } i = start.location;
            } else { i++; }
            searchRange = NSMakeRange(i, [escaped length] - i);
        }
		
        return escaped;    // Note this is autoreleased
    }
}

- (NSString *)kv_encodeHTMLCharacterEntities {
    NSMutableString *encoded = [NSMutableString stringWithString:self];
	
    // @"&amp;"
    NSRange range = [self rangeOfString:@"&"];
    if (range.location != NSNotFound) {
        [encoded replaceOccurrencesOfString:@"&"
                                 withString:@"&amp;"
                                    options:NSLiteralSearch
                                      range:NSMakeRange(0, [encoded length])];
    }
	
    // @"&lt;"
    range = [self rangeOfString:@"<"];
    if (range.location != NSNotFound) {
        [encoded replaceOccurrencesOfString:@"<"
                                 withString:@"&lt;"
                                    options:NSLiteralSearch
                                      range:NSMakeRange(0, [encoded length])];
    }
	
    // @"&gt;"
    range = [self rangeOfString:@">"];
    if (range.location != NSNotFound) {
        [encoded replaceOccurrencesOfString:@">"
                                 withString:@"&gt;"
                                    options:NSLiteralSearch
                                      range:NSMakeRange(0, [encoded length])];
    }
	
    return encoded;
}

@end