Foundation/GTMNSString+HTML.m

//
//  GTMNSString+HTML.m
//  Dealing with NSStrings that contain HTML
//
//  Copyright 2006-2008 Google 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.
//

#import "GTMDefines.h"
#import "GTMNSString+HTML.h"

// Export a nonsense symbol to suppress a libtool warning when this is linked
// alone in a static lib.
__attribute__((visibility("default")))
    char GTMNSString_HTMLExportToSuppressLibToolWarning = 0;

typedef struct {
  NSString *escapeSequence;
  unichar uchar;
} HTMLEscapeMap;

// Taken from http://www.w3.org/TR/xhtml1/dtds.html#a_dtd_Special_characters
// Ordered by uchar lowest to highest for bsearching
static HTMLEscapeMap gAsciiHTMLEscapeMap[] = {
  // A.2.2. Special characters
  { @""", 34 },
  { @"&", 38 },
  { @"'", 39 },
  { @"<", 60 },
  { @">", 62 },

    // A.2.1. Latin-1 characters
  { @" ", 160 },
  { @"¡", 161 },
  { @"¢", 162 },
  { @"£", 163 },
  { @"¤", 164 },
  { @"¥", 165 },
  { @"¦", 166 },
  { @"§", 167 },
  { @"¨", 168 },
  { @"©", 169 },
  { @"ª", 170 },
  { @"«", 171 },
  { @"¬", 172 },
  { @"­", 173 },
  { @"®", 174 },
  { @"¯", 175 },
  { @"°", 176 },
  { @"±", 177 },
  { @"²", 178 },
  { @"³", 179 },
  { @"´", 180 },
  { @"µ", 181 },
  { @"¶", 182 },
  { @"·", 183 },
  { @"¸", 184 },
  { @"¹", 185 },
  { @"º", 186 },
  { @"»", 187 },
  { @"¼", 188 },
  { @"½", 189 },
  { @"¾", 190 },
  { @"¿", 191 },
  { @"À", 192 },
  { @"Á", 193 },
  { @"Â", 194 },
  { @"Ã", 195 },
  { @"Ä", 196 },
  { @"Å", 197 },
  { @"Æ", 198 },
  { @"Ç", 199 },
  { @"È", 200 },
  { @"É", 201 },
  { @"Ê", 202 },
  { @"Ë", 203 },
  { @"Ì", 204 },
  { @"Í", 205 },
  { @"Î", 206 },
  { @"Ï", 207 },
  { @"Ð", 208 },
  { @"Ñ", 209 },
  { @"Ò", 210 },
  { @"Ó", 211 },
  { @"Ô", 212 },
  { @"Õ", 213 },
  { @"Ö", 214 },
  { @"×", 215 },
  { @"Ø", 216 },
  { @"Ù", 217 },
  { @"Ú", 218 },
  { @"Û", 219 },
  { @"Ü", 220 },
  { @"Ý", 221 },
  { @"Þ", 222 },
  { @"ß", 223 },
  { @"à", 224 },
  { @"á", 225 },
  { @"â", 226 },
  { @"ã", 227 },
  { @"ä", 228 },
  { @"å", 229 },
  { @"æ", 230 },
  { @"ç", 231 },
  { @"è", 232 },
  { @"é", 233 },
  { @"ê", 234 },
  { @"ë", 235 },
  { @"ì", 236 },
  { @"í", 237 },
  { @"î", 238 },
  { @"ï", 239 },
  { @"ð", 240 },
  { @"ñ", 241 },
  { @"ò", 242 },
  { @"ó", 243 },
  { @"ô", 244 },
  { @"õ", 245 },
  { @"ö", 246 },
  { @"÷", 247 },
  { @"ø", 248 },
  { @"ù", 249 },
  { @"ú", 250 },
  { @"û", 251 },
  { @"ü", 252 },
  { @"ý", 253 },
  { @"þ", 254 },
  { @"ÿ", 255 },

  // A.2.2. Special characters cont'd
  { @"Œ", 338 },
  { @"œ", 339 },
  { @"Š", 352 },
  { @"š", 353 },
  { @"Ÿ", 376 },

  // A.2.3. Symbols
  { @"ƒ", 402 },

  // A.2.2. Special characters cont'd
  { @"ˆ", 710 },
  { @"˜", 732 },

  // A.2.3. Symbols cont'd
  { @"Α", 913 },
  { @"Β", 914 },
  { @"Γ", 915 },
  { @"Δ", 916 },
  { @"Ε", 917 },
  { @"Ζ", 918 },
  { @"Η", 919 },
  { @"Θ", 920 },
  { @"Ι", 921 },
  { @"Κ", 922 },
  { @"Λ", 923 },
  { @"Μ", 924 },
  { @"Ν", 925 },
  { @"Ξ", 926 },
  { @"Ο", 927 },
  { @"Π", 928 },
  { @"Ρ", 929 },
  { @"Σ", 931 },
  { @"Τ", 932 },
  { @"Υ", 933 },
  { @"Φ", 934 },
  { @"Χ", 935 },
  { @"Ψ", 936 },
  { @"Ω", 937 },
  { @"α", 945 },
  { @"β", 946 },
  { @"γ", 947 },
  { @"δ", 948 },
  { @"ε", 949 },
  { @"ζ", 950 },
  { @"η", 951 },
  { @"θ", 952 },
  { @"ι", 953 },
  { @"κ", 954 },
  { @"λ", 955 },
  { @"μ", 956 },
  { @"ν", 957 },
  { @"ξ", 958 },
  { @"ο", 959 },
  { @"π", 960 },
  { @"ρ", 961 },
  { @"ς", 962 },
  { @"σ", 963 },
  { @"τ", 964 },
  { @"υ", 965 },
  { @"φ", 966 },
  { @"χ", 967 },
  { @"ψ", 968 },
  { @"ω", 969 },
  { @"ϑ", 977 },
  { @"ϒ", 978 },
  { @"ϖ", 982 },

  // A.2.2. Special characters cont'd
  { @" ", 8194 },
  { @" ", 8195 },
  { @" ", 8201 },
  { @"‌", 8204 },
  { @"‍", 8205 },
  { @"‎", 8206 },
  { @"‏", 8207 },
  { @"–", 8211 },
  { @"—", 8212 },
  { @"‘", 8216 },
  { @"’", 8217 },
  { @"‚", 8218 },
  { @"“", 8220 },
  { @"”", 8221 },
  { @"„", 8222 },
  { @"†", 8224 },
  { @"‡", 8225 },
    // A.2.3. Symbols cont'd
  { @"•", 8226 },
  { @"…", 8230 },

  // A.2.2. Special characters cont'd
  { @"‰", 8240 },

  // A.2.3. Symbols cont'd
  { @"′", 8242 },
  { @"″", 8243 },

  // A.2.2. Special characters cont'd
  { @"‹", 8249 },
  { @"›", 8250 },

  // A.2.3. Symbols cont'd
  { @"‾", 8254 },
  { @"⁄", 8260 },

  // A.2.2. Special characters cont'd
  { @"€", 8364 },

  // A.2.3. Symbols cont'd
  { @"ℑ", 8465 },
  { @"℘", 8472 },
  { @"ℜ", 8476 },
  { @"™", 8482 },
  { @"ℵ", 8501 },
  { @"←", 8592 },
  { @"↑", 8593 },
  { @"→", 8594 },
  { @"↓", 8595 },
  { @"↔", 8596 },
  { @"↵", 8629 },
  { @"⇐", 8656 },
  { @"⇑", 8657 },
  { @"⇒", 8658 },
  { @"⇓", 8659 },
  { @"⇔", 8660 },
  { @"∀", 8704 },
  { @"∂", 8706 },
  { @"∃", 8707 },
  { @"∅", 8709 },
  { @"∇", 8711 },
  { @"∈", 8712 },
  { @"∉", 8713 },
  { @"∋", 8715 },
  { @"∏", 8719 },
  { @"∑", 8721 },
  { @"−", 8722 },
  { @"∗", 8727 },
  { @"√", 8730 },
  { @"∝", 8733 },
  { @"∞", 8734 },
  { @"∠", 8736 },
  { @"∧", 8743 },
  { @"∨", 8744 },
  { @"∩", 8745 },
  { @"∪", 8746 },
  { @"∫", 8747 },
  { @"∴", 8756 },
  { @"∼", 8764 },
  { @"≅", 8773 },
  { @"≈", 8776 },
  { @"≠", 8800 },
  { @"≡", 8801 },
  { @"≤", 8804 },
  { @"≥", 8805 },
  { @"⊂", 8834 },
  { @"⊃", 8835 },
  { @"⊄", 8836 },
  { @"⊆", 8838 },
  { @"⊇", 8839 },
  { @"⊕", 8853 },
  { @"⊗", 8855 },
  { @"⊥", 8869 },
  { @"⋅", 8901 },
  { @"⌈", 8968 },
  { @"⌉", 8969 },
  { @"⌊", 8970 },
  { @"⌋", 8971 },
  { @"⟨", 9001 },
  { @"⟩", 9002 },
  { @"◊", 9674 },
  { @"♠", 9824 },
  { @"♣", 9827 },
  { @"♥", 9829 },
  { @"♦", 9830 }
};

// Taken from http://www.w3.org/TR/xhtml1/dtds.html#a_dtd_Special_characters
// This is table A.2.2 Special Characters
static HTMLEscapeMap gUnicodeHTMLEscapeMap[] = {
  // C0 Controls and Basic Latin
  { @""", 34 },
  { @"&", 38 },
  { @"'", 39 },
  { @"<", 60 },
  { @">", 62 },

  // Latin Extended-A
  { @"Œ", 338 },
  { @"œ", 339 },
  { @"Š", 352 },
  { @"š", 353 },
  { @"Ÿ", 376 },

  // Spacing Modifier Letters
  { @"ˆ", 710 },
  { @"˜", 732 },

  // General Punctuation
  { @" ", 8194 },
  { @" ", 8195 },
  { @" ", 8201 },
  { @"‌", 8204 },
  { @"‍", 8205 },
  { @"‎", 8206 },
  { @"‏", 8207 },
  { @"–", 8211 },
  { @"—", 8212 },
  { @"‘", 8216 },
  { @"’", 8217 },
  { @"‚", 8218 },
  { @"“", 8220 },
  { @"”", 8221 },
  { @"„", 8222 },
  { @"†", 8224 },
  { @"‡", 8225 },
  { @"‰", 8240 },
  { @"‹", 8249 },
  { @"›", 8250 },
  { @"€", 8364 },
};


// Utility function for Bsearching table above
static int EscapeMapCompare(const void *ucharVoid, const void *mapVoid) {
  const unichar *uchar = (const unichar*)ucharVoid;
  const HTMLEscapeMap *map = (const HTMLEscapeMap*)mapVoid;
  int val;
  if (*uchar > map->uchar) {
    val = 1;
  } else if (*uchar < map->uchar) {
    val = -1;
  } else {
    val = 0;
  }
  return val;
}

@implementation NSString (GTMNSStringHTMLAdditions)

- (NSString *)gtm_stringByEscapingHTMLUsingTable:(HTMLEscapeMap*)table
                                          ofSize:(NSUInteger)size
                                 escapingUnicode:(BOOL)escapeUnicode {
  NSUInteger length = [self length];
  if (!length) {
    return self;
  }

  NSMutableString *finalString = [NSMutableString string];
  NSMutableData *data2 = [NSMutableData dataWithCapacity:sizeof(unichar) * length];

  // this block is common between GTMNSString+HTML and GTMNSString+XML but
  // it's so short that it isn't really worth trying to share.
  const unichar *buffer = CFStringGetCharactersPtr((CFStringRef)self);
  if (!buffer) {
    // We want this buffer to be autoreleased.
    NSMutableData *data = [NSMutableData dataWithLength:length * sizeof(UniChar)];
    if (!data) {
      // COV_NF_START  - Memory fail case
      _GTMDevLog(@"couldn't alloc buffer");
      return nil;
      // COV_NF_END
    }
    [self getCharacters:[data mutableBytes]];
    buffer = [data bytes];
  }

  if (!buffer || !data2) {
    // COV_NF_START
    _GTMDevLog(@"Unable to allocate buffer or data2");
    return nil;
    // COV_NF_END
  }

  unichar *buffer2 = (unichar *)[data2 mutableBytes];

  NSUInteger buffer2Length = 0;

  for (NSUInteger i = 0; i < length; ++i) {
    HTMLEscapeMap *val = bsearch(&buffer[i], table,
                                 size / sizeof(HTMLEscapeMap),
                                 sizeof(HTMLEscapeMap), EscapeMapCompare);
    if (val || (escapeUnicode && buffer[i] > 127)) {
      if (buffer2Length) {
        CFStringAppendCharacters((CFMutableStringRef)finalString,
                                 buffer2,
                                 buffer2Length);
        buffer2Length = 0;
      }
      if (val) {
        [finalString appendString:val->escapeSequence];
      }
      else {
        _GTMDevAssert(escapeUnicode && buffer[i] > 127, @"Illegal Character");
        [finalString appendFormat:@"&#%d;", buffer[i]];
      }
    } else {
      buffer2[buffer2Length] = buffer[i];
      buffer2Length += 1;
    }
  }
  if (buffer2Length) {
    CFStringAppendCharacters((CFMutableStringRef)finalString,
                             buffer2,
                             buffer2Length);
  }
  return finalString;
}

- (NSString *)gtm_stringByEscapingForHTML {
  return [self gtm_stringByEscapingHTMLUsingTable:gUnicodeHTMLEscapeMap
                                           ofSize:sizeof(gUnicodeHTMLEscapeMap)
                                  escapingUnicode:NO];
} // gtm_stringByEscapingHTML

- (NSString *)gtm_stringByEscapingForAsciiHTML {
  return [self gtm_stringByEscapingHTMLUsingTable:gAsciiHTMLEscapeMap
                                           ofSize:sizeof(gAsciiHTMLEscapeMap)
                                  escapingUnicode:YES];
} // gtm_stringByEscapingAsciiHTML

- (NSString *)gtm_stringByUnescapingFromHTML {
  NSRange range = NSMakeRange(0, [self length]);
  NSRange subrange = [self rangeOfString:@"&" options:NSBackwardsSearch range:range];

  // if no ampersands, we've got a quick way out
  if (subrange.length == 0) return self;
  NSMutableString *finalString = [NSMutableString stringWithString:self];
  do {
    NSRange semiColonRange = NSMakeRange(subrange.location, NSMaxRange(range) - subrange.location);
    semiColonRange = [self rangeOfString:@";" options:0 range:semiColonRange];
    range = NSMakeRange(0, subrange.location);
    // if we don't find a semicolon in the range, we don't have a sequence
    if (semiColonRange.location == NSNotFound) {
      continue;
    }
    NSRange escapeRange = NSMakeRange(subrange.location, semiColonRange.location - subrange.location + 1);
    NSString *escapeString = [self substringWithRange:escapeRange];
    NSUInteger length = [escapeString length];
    // a squence must be longer than 3 (&lt;) and less than 11 (&thetasym;)
    if (length > 3 && length < 11) {
      if ([escapeString characterAtIndex:1] == '#') {
        unichar char2 = [escapeString characterAtIndex:2];
        if (char2 == 'x' || char2 == 'X') {
          // Hex escape squences &#xa3;
          NSString *hexSequence = [escapeString substringWithRange:NSMakeRange(3, length - 4)];
          NSScanner *scanner = [NSScanner scannerWithString:hexSequence];
          unsigned value;
          if ([scanner scanHexInt:&value] &&
              value > 0
              && [scanner scanLocation] == length - 4) {
            if (value < USHRT_MAX) {
              unichar uchar = (unichar)value;
              NSString *charString = [NSString stringWithCharacters:&uchar length:1];
              [finalString replaceCharactersInRange:escapeRange withString:charString];
            } else if (value >= 0x10000 && value <= 0x10FFFF) {
              // code points in unicode supplementary planes
              int subtractedValue = value - 0x10000;
              unichar uchars[2];
              uchars[0] = 0xD800 + (subtractedValue >> 10);
              uchars[1] = 0xDC00 + (subtractedValue & 0x3FF);
              NSString *charString = [NSString stringWithCharacters:uchars length:2];
              if (charString) {
                [finalString replaceCharactersInRange:escapeRange withString:charString];
              }
            }
          }
        } else {
          // Decimal Sequences &#123;
          NSString *numberSequence = [escapeString substringWithRange:NSMakeRange(2, length - 3)];
          NSScanner *scanner = [NSScanner scannerWithString:numberSequence];
          int value;
          if ([scanner scanInt:&value] &&
              value > 0
              && [scanner scanLocation] == length - 3) {
            if (value < USHRT_MAX) {
              unichar uchar = (unichar)value;
              NSString *charString = [NSString stringWithCharacters:&uchar length:1];
              [finalString replaceCharactersInRange:escapeRange withString:charString];
            } else if (value >= 0x10000 && value <= 0x10FFFF) {
              // code points in unicode supplementary planes
              int subtractedValue = value - 0x10000;
              unichar uchars[2];
              uchars[0] = 0xD800 + (subtractedValue >> 10);
              uchars[1] = 0xDC00 + (subtractedValue & 0x3FF);
              NSString *charString = [NSString stringWithCharacters:uchars length:2];
              if (charString) {
                [finalString replaceCharactersInRange:escapeRange withString:charString];
              }
            }
          }
        }
      } else {
        // "standard" sequences
        for (unsigned i = 0; i < sizeof(gAsciiHTMLEscapeMap) / sizeof(HTMLEscapeMap); ++i) {
          if ([escapeString isEqualToString:gAsciiHTMLEscapeMap[i].escapeSequence]) {
            [finalString replaceCharactersInRange:escapeRange withString:[NSString stringWithCharacters:&gAsciiHTMLEscapeMap[i].uchar length:1]];
            break;
          }
        }
      }
    }
  } while ((subrange = [self rangeOfString:@"&" options:NSBackwardsSearch range:range]).length != 0);
  return finalString;
} // gtm_stringByUnescapingHTML



@end