Re: Problem with CFXMLCreateStringByEscapingEntities to replace special xml chars?

FROM : Steven Kramer
DATE : Tue Nov 02 13:46:42 2004

Op 17-okt-04 om 6:58 heeft Benjamin Levy het volgende geschreven:

> Hello,
> I've used CFXMLCreateStringByUnescapingEntities before with no 
> problems, but I'm getting a consistent but unexpected result with 
> CFXMLCreateStringByEscapingEntities now that I'm using it for the 
> first time.  It seems that the returned string only includes up to the 
> last replaced entity and cuts the rest of the string out and if there 
> are no entities it returns an empty string.
>
> NSString* a = @"one < two";
> NSString* b = (NSString*)CFXMLCreateStringByEscapingEntities( 
> kCFAllocatorDefault, (CFStringRef)a, NULL );
> NSLog( @"String \"%@\" became \"%@\"", a, b );
>
> Results in: String "one < two" became "one &lt;"
>
> Not much comes up when searching for 
> CFXMLCreateStringByEscapingEntities, but is this a known behavior 
> and/or bug?  Am I somehow doing something wrong here?
>


Benjamin,

I just checked the source for this function (in 10.3.5, 
<http://darwinsource.opendarwin.org/10.3.5/CF-299.31/Parsing.subproj/
CFXMLParser.c>)  and it is indeed badly broken. You're better off 
writing a Cocoa replacement for now.

There are two problems:
1. the entities dictionary is ignored
2. you will get a correct substring up to and including the final 
entity, but not what comes after

The very crude, very slow and mostly untested code below at least fixes 
#2

Regards

    Steven

@implementation NSString (CBEscapeXMLEntities)

- (NSString*) escapedString
{
   NSMutableString* escaped = [[self mutableCopy] autorelease];// really, 
really broken (NSString*) ::CFXMLCreateStringByEscapingEntities (nil, 
(CFStringRef) self, nil);
   [escaped replaceOccurrencesOfString: @"&" withString: @"&amp;" 
options: 0 range: NSMakeRange (0, [escaped length])];
   [escaped replaceOccurrencesOfString: @"<" withString: @"&lt;" options: 
0 range: NSMakeRange (0, [escaped length])];
   [escaped replaceOccurrencesOfString: @">" withString: @"&gt;" options: 
0 range: NSMakeRange (0, [escaped length])];
   [escaped replaceOccurrencesOfString: @"\"" withString: @"&quot;" 
options: 0 range: NSMakeRange (0, [escaped length])];
   return [escaped copy];
}

@end

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