How would I go about removing the "&" symbol from a string. It's making my xml parser fail.
I have tried
[currentParsedCharacterData setString: [currentParsedCharacterData stringByReplacingOccurrencesOfString:#"&" withString:#"and"]];
But it seems to have no effect
Really what this boils down to is you want to gracefully handle invalid XML. The XML Parser is properly telling you that this XML is invalid, and is thusly failing to parse. Assuming you have no control over this XML content, I would suggest pre-parsing it for common errors like this, the output of which would be a sanitized XML doc that has a better chance of success.
To sanitize the doc, it may be as simple as doing search and replace, the problem with just doing a blanket replace on any & is that there are valid uses of &, for example & or ©. You would end up munging the XML by creating something like this: andcopy;
You could search for "ampersand space" but that won't catch a string that has an ampersand as the last character (an out-case that might be easily handled). What you are really searching for are occurrences of & that are not followed by a ; or those of which where any type of whitespace is encountered before the following ; because the semi-colon is fine on its own.
If you need more power because you need to detect this, and other errors, I would suggest going to NSScanner or RegEx matching to search for occurrences of this and other common errors during your sanitization step. It is also very common for XML files to be rather large things, so you need to be careful when dealing with these as in-memory strings as this can easily lead to application crashes. Breaking it up into manageable chunks is something NSScanner can do very well.
For a quick attempt look at stringByReplacingOccurrencesOfString on NSString
NSString* str = #"a & b";
[str stringByReplacingOccurrencesOfString:#"&" withString:#"and"]; // better replace by &
However you should also deal with other characters i.e. < >
Related
I have a CoreData/SQLite application in which I have "Parent Categories" and "Categories". I do not have control over the data, some of the "Parent Categories" values have trailing white spaces.
I could use CONTAINS (or I should say it works with CONTAINS but this is something I can not use). For example I have 2 entries, MEN and MENS. If I use CONTAINS I will return both records, you can see how this would be an issue.
I can easily trim on my side, but the predicate will compare that with the database and will not match. So my question is how can I account for whitespaces in the predicate, if possible at all.
I have a category "MENS" which someone has selected in the application, and it is compared against "MENS " in the database.
I would trim the data prior to doing the lookup. You can do this easily usingstringByTrimmingCharactersInSet. By doing it beforehand, you'll also avoid any performance hit. That could be expensive if you're doing a character based comparison withCONTAINS.
So, let's say your search string is "MEN".
Here's the way to strip out any dodgy characters:
NSString *trimmed = [#"MEN " stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
There's alsowhitespaceAndNewlineCharacterSetwhich does what it says on the tin.
Alternatively, it's easy to create your own custom character of stuff you want to trim.
For that, have a look at:
NSCharacterSet Class Reference
and
Apple's String Programming Guide
I have problem with parsing XML.
I parsed data of cities, Amsterdam & Den Bosch.
Amsterdam works fine but Den Bosch does not.
No doubt it is due to space problem.
Den Bosch has a white space.
Should I trim the whitespace in my application or the web service?
Which would be the best to handle the space problem?
EDIT:
The OP and #PeterMurray-Rust seem to agree that the problem is that the third-party app returns URL-escaped strings of the form:
"Den%20Bosch"
%20 is not recognized by XML as anything special and that it will be necessary to replace occurrences by spaces. A typical scripting approach would be
s/%20/ /g
This is likely to be quite a common problem although I'm not clear why content should be URL-encoded.
[OP please comment if I have got this wrong]
From your update I assume that the data is something like:
<city>Den%20Bosch</city>
The string "%20" is three characters which XML does not regard as having any specific meaning. Depending on your language or whether you use XSLT you will need to replace them. In Java and the XOM library I might write
String value = cityNode.getValue().replaceAll("%20", " ");
I can't help with the specifics of Cocoa - I think you'll have to investigate the API to find how to get content values.
I Assume that you are parsing xml at application level and also by white space you mean the trailing white spaces and not the one in between the words "Den" and "Bosch". In anycase, I think you can trim the spaces at web service level, since you can be rest assured that any call coming from any other application using this web service need not have to trim the spaces since web service handles that internally. This would be a one-point change for you.
Don't know much about cocoa and your xml as well. City names, are these inner text of node or tag name. If it is in tag name or attributes without quotes, it will fail. If it is in inner text, it should work. However, there is CDATA fragment which tells the parser to ignore the contents
This is the code i implemented its working fine..........
if ([appDelegate.cityListArray count]>0) {
aDJInfo=[appDelegate.cityListArray objectAtIndex:indexPath.row];
//http://compliantbox.com/party_temperature/citysearch.php?city=Amsterdam&latitude=52.366125&longitude=4.899171
url=#"http://compliantbox.com/party_temperature/citysearch.php?city=";
NSString *string=[aDJInfo.city_Name stringByReplacingOccurrencesOfString:#" " withString:#"%20"];
url=[url stringByAppendingString:string];
NSLog(#"abbbbbbbbbbb %#",string);
url=[url stringByAppendingString:#"&latitude=52.366125&longitude=4.899171"];
[self parseEventName:[[NSURL alloc]initWithString:url]];
}
}
#All thanks a lot..
I am using RegexKitLite and I'm trying to match a pattern.
The following regex patterns do not capture my word that includes N with a titlde: ñ.
Is there a string conversion I am missing?
subjectString = #"define_añadir";
//regexString = #"^define_(.*)"; //this pattern does not match, so I assume to add the ñ
//regexString = #"^define_([.ñ]*)"; //tried this pattern first with a range
regexString = #"^define_((?:\\w|ñ)*)"; //tried second
NSString *captured= [subjectString stringByMatching:regexString capture:1L];
//I want captured == añadir
Looks like an encoding problem to me. Either you're saving the source code in an encoding that can't handle that character (like ASCII), or the compiler is using the wrong encoding to read the source files. Going back to the original regex, try creating the subject string like this:
subjectString = #"define_a\xC3\xB1adir";
or this:
subjectString = #"define_a\u00F1adir";
If that works, check the encoding of your source code files and make sure it's the same encoding the compiler expects.
EDIT: I've never worked with the iPhone technology stack, but according to this doc you should be using the stringWithUTF8String method to create the NSString, not the #"" literal syntax. In fact, it says you should never use non-ASCII characters (that is, anything not in the range 0x00..0x7F) in your code; that way you never have to worry about the source file's encoding. That's good advice no matter what language or toolset you're using.
Hey guys, given a data set in plain text such as the following:
==Events==
* [[312]] – [[Constantine the Great]] is said to have received his famous [[Battle of Milvian Bridge#Vision of Constantine|Vision of the Cross]].
* [[710]] – [[Saracen]] invasion of [[Sardinia]].
* [[939]] – [[Edmund I of England|Edmund I]] succeeds [[Athelstan of England|Athelstan]] as [[King of England]].
*[[1275]] – Traditional founding of the city of [[Amsterdam]].
*[[1524]] – [[Italian Wars]]: The French troops lay siege to [[Pavia]].
*[[1553]] – Condemned as a [[Heresy|heretic]], [[Michael Servetus]] is [[burned at the stake]] just outside [[Geneva]].
*[[1644]] – [[Second Battle of Newbury]] in the [[English Civil War]].
*[[1682]] – [[Philadelphia]], [[Pennsylvania]] is founded.
I would like to end up with an NSDictionary or other form of collection so that I can have the year (The Number on the left) mapping to the excerpt (The text on the right). So this is what the 'template' is like:
*[[YEAR]] – THE_TEXT
Though I would like the excerpt to be plain text, that is, no wiki markup so no [[ sets. Actually, this could prove difficult with alias links such as [[Edmund I of England|Edmund I]].
I am not all that experienced with regular expressions so I have a few questions. Should I first try to 'beautify' the data? For example, removing the first line which will always be ==Events==, and removing the [[ and ]] occurrences?
Or perhaps a better solution: Should I do this in passes? So for example, the first pass I can separate each line into * [[710]] and [[Saracen]] invasion of [[Sardinia]]. and store them into different NSArrays.
Then go through the first NSArray of years and only get the text within the [[]] (I say text and not number because it can be 530 BC), so * [[710]] becomes 710.
And then for the excerpt NSArray, go through and if an [[some_article|alias]] is found, make it only be [[alias]] somehow, and then remove all of the [[ and ]] sets?
Is this possible? Should I use regular expressions? Are there any ideas you can come up with for regular expressions that might help?
Thanks! I really appreciate it.
EDIT: Sorry for the confusion, but I only want to parse the above data. Assume that that's the only type of markup that I will encounter. I'm not necessarily looking forward to parsing wiki markup in general, unless there is already a pre-existing library which does this. Thanks again!
This code assumes you are using RegexKitLite:
NSString *data = #"* [[312]] – [[Constantine the Great]] is said to have received his famous [[Battle of Milvian Bridge#Vision of Constantine|Vision of the Cross]].\n\
* [[710]] – [[Saracen]] invasion of [[Sardinia]].\n\
* [[939]] – [[Edmund I of England|Edmund I]] succeeds [[Athelstan of England|Athelstan]] as [[King of England]].\n\
*[[1275]] – Traditional founding of the city of [[Amsterdam]].";
NSString *captureRegex = #"(?i)(?:\\* *\\[\\[)([0-9]*)(?:\\]\\] \\– )(.*)";
NSRange captureRange;
NSRange stringRange;
stringRange.location = 0;
stringRange.length = data.length;
do
{
captureRange = [data rangeOfRegex:captureRegex inRange:stringRange];
if ( captureRange.location != NSNotFound )
{
NSString *year = [data stringByMatching:captureRegex options:RKLNoOptions inRange:stringRange capture:1 error:NULL];
NSString *textStuff = [data stringByMatching:captureRegex options:RKLNoOptions inRange:stringRange capture:2 error:NULL];
stringRange.location = captureRange.location + captureRange.length;
stringRange.length = data.length - stringRange.location;
NSLog(#"Year:%#, Stuff:%#", year, textStuff);
}
}
while ( captureRange.location != NSNotFound );
Note that you really need to study up on RegEx's to build these well, but here's what the one I have is saying:
(?i)
Ignore case, I could have left that out since I'm not matching letters.
(?:\* *\[\[)
?: means don't capture this block, I escape * to match it, then there are zero or more spaces (" *") then I escape out two brackets (since brackets are also special characters in a regex).
([0-9]*)
Grab anything that is a number.
(?:\]\] \– )
Here's where we ignore stuff again, basically matching " – ". Note any "\" in the regex, I have to add another one to in the Objective-C string above since "\" is a special character in a string... and yes that means matching a regex escaped single "\" ends up as "\\" in an Obj-C string.
(.*)
Just grab anything else, by default the RegEX engine will stop matching at the end of a line which is why it doesn't just match everything else. You'll have to add code to strip out the [[LINK]] stuff from the text.
The NSRange variables are used to keep matching through the file without re-matching original matches. So to speak.
Don't forget after you add the RegExKitLite class files, you also need to add the special linker flag or you'll get lots of link errors (the RegexKitLite site has installation instructions).
I'm no good with regular expressions, but this sounds like a job for them. I imagine a regex would sort this out for you quite easily.
Have a look at the RegexKitLite library.
If you want to be able to parse Wikitext in general, you have a lot of work to do. Just one complicating factor is templates. How much effort do you want to go to cope with these?
If you're serious about this, you probably should be looking for an existing library which parses Wikitext. A brief look round finds this CPAN library, but I have not used it, so I can't cite it as a personal recommendation.
Alternatively, you might want to take a simpler approach and decide which particular parts of Wikitext you're going to cope with. This might be, for example, links and headings, but not lists. Then you have to focus on each of these and turn the Wikitext into whatever you want that to look like. Yes, regular expressions will help a lot with this bit, so read up on them, and if you have specific problems, come back and ask.
Good luck!
I am writing a backend application which needs to be able to send multiple SQL commands to a MySQL server.
MySQL >= 5.x support multiple statements, but unfortunately we are interfacing with MySQL 4.x.
I am trying to find a way (hint: regex) to split SQL statements by their semicolon, but it should ignore semicolons in single and double quotes strings.
http://www.dev-explorer.com/articles/multiple-mysql-queries has a very nice regex to do that, but doesn't support double quotes.
I'd be happy to hear your suggestions.
Can't be done with regex, it's insufficiently powerful to parse SQL. There may be an SQL parser available for your language — which is it? — but parsing SQL is quite hard, especially given the range of different syntaxes available. Even in MySQL alone there are many SQL_MODE flags on a server and connection level that can affect how basic strings and comments are parsed, making statements behave quite differently.
The example at dev-explorer goes to amusing lengths to try to cope with escaped apostrophes and trailing strings, but will still fail for many valid combinations of them, not to mention the double quotes, backticks, the various comment syntaxes, or ANSI SQL_MODE.
As bobince said, regular expressions are probably not going to be powerful enough to do this. They're certainly not going to be powerful enough to do it in any halfway elegant manner. The second link cdonner provided also does not address this; most answers there were trying to talk the questioner out of doing this without semicolons; if he had taken the general advice, then he'd have ended up where you are.
I think the quickest path to solving this is going to be with a string scanner function, that examines every character of the string in sequence, and reacts based on a bit of stored state. Rough pseudocode:
Read in a character
If the character is not special, CONTINUE
If the character is escaped (checking this probably requires examining the previous character), CONTINUE
If the character would start a new string or end an existing one, toggle a flag IN_STRING (you might need multiple flags for different string types... I've honestly tried and succeeded at remaining ignorant of the minutiae of SQL quoting/escaping) and CONTINUE
If the character is a semicolon AND we are not currently in a string, we have found a query! OUTPUT it and CONTINUE scanning until the end of the string.
Language parsing is not any of my areas of experience, so you'll want to consider that approach carefully; nonetheless, it's going to be fast (with C-style strings, none of those steps are at all expensive, save possibly for the OUTPUT, depending on what "outputting" means in your context) and I think it should get the job done.
maybe with the following Java Regexp? check the test...
#Test
public void testRegexp() {
String s = //
"SELECT 'hello;world' \n" + //
"FROM DUAL; \n" + //
"\n" + //
"SELECT 'hello;world' \n" + //
"FROM DUAL; \n" + //
"\n";
String regexp = "([^;]*?('.*?')?)*?;\\s*";
assertEquals("<statement><statement>", s.replaceAll(regexp, "<statement>"));
}
I would suggest seeing if you can redefine the problem space so the need to send multiple queries separated only by their terminator is not required.
Try this. Just replaced the 1st ' with \" and it seems to work for both ' and "
;+(?=([^\"|^\\']['|\\'][^'|^\\']['|\\'])[^'|^\\'][^'|^\\']$)