ROT13編碼/解碼字符串，但不改變括號內的字符[]

Question

我有一個簡單的ROT13方法來編碼或解碼字符串。

+ (NSString *)ROT13encodeString:(NSString *)aString { 

    if (!aString) { 
     return nil; 
    } 

    // Find text between brackets 
    NSCharacterSet *delimiters = [NSCharacterSet characterSetWithCharactersInString:@"[]"]; 
    NSArray *splitString = [aString componentsSeparatedByCharactersInSet:delimiters]; 
    // ??? 

    NSString *newString; 
    unsigned length; 
    unichar *buf; 
    unsigned i; 

    length = [aString length]; 
    buf = malloc((length + 1) * sizeof(unichar)); 
    [aString getCharacters:buf]; 
    buf[length] = (unichar)0; // not really needed.... 
    for (i = 0; i < length; i++) { 
     if (buf[i] >= (unichar)'a' && buf[i] <= (unichar) 'z') { 
      buf[i] += 13; 
      if (buf[i] > 'z') buf[i] -= 26; 
     } else if (buf[i] >= (unichar)'A' && buf[i] <= (unichar) 'Z') { 
      buf[i] += 13; 
      if (buf[i] > 'Z') buf[i] -= 26; 
     } 
    } 
    newString = [NSString stringWithCharacters:buf length:length]; 
    free(buf); 
    return newString; 

} 

但是，在要編碼的文本中，放置在方括號[]中的是「安全」字。包括括號在內的單詞不應編碼，它們總是需要處於非編碼狀態。

我想我可以拉出來的括號內的文本的所有occururances，但不知道它是如何幫助：

NSCharacterSet *delimiters = [NSCharacterSet characterSetWithCharactersInString:@"[]"]; 
NSArray *splitString = [aString componentsSeparatedByCharactersInSet:delimiters]; 

我怎麼能修改我目前的方法，包括本？

Answer 1

我不Objective-C代碼，但我認爲這應該是接近：

+ (NSString *)ROT13encodeString:(NSString *)aString { 

    if (!aString) { 
     return nil; 
    } 

    // Find text between brackets 
    NSCharacterSet *delimiters = [NSCharacterSet characterSetWithCharactersInString:@"[]"]; 
    NSArray *splitString = [aString componentsSeparatedByCharactersInSet:delimiters]; 
    // ??? 

    NSString *newString; 
    unsigned length; 
    unichar *buf; 
    unsigned i; 
    unsigned level; 

    length = [aString length]; 
    buf = malloc((length + 1) * sizeof(unichar)); 
    [aString getCharacters:buf]; 
    buf[length] = (unichar)0; // not really needed.... 
    level = 0; 
    for (i = 0; i < length; i++) { 
     if (buf[i] == (unichar)'[') { 
      level++; 
     } else if (buf[i] == (unichar)']') { 
      level--; 
     } else if (level==0 && buf[i] >= (unichar)'a' && buf[i] <= (unichar) 'z') { 
      buf[i] += 13; 
      if (buf[i] > 'z') buf[i] -= 26; 
     } else if (level==0 && buf[i] >= (unichar)'A' && buf[i] <= (unichar) 'Z') { 
      buf[i] += 13; 
      if (buf[i] > 'Z') buf[i] -= 26; 
     } 
    } 
    newString = [NSString stringWithCharacters:buf length:length]; 
    free(buf); 
    return newString; 

}