Remove repeating substring from string

Question

I cannot think of the a function to remove a repeating substring from my string. My string looks like this:

"<bold><bold>Rutger</bold> Roger</bold> rented a <bold>testitem zero dollars</bold> from <bold>Rutger</bold>."

And if <bold> is followed by another <bold> I want to remove the second <bold>. When removing that second <bold> I also want to remove the first </bold> that follows.

So the output that I'm looking for should be this:

"<bold>Rutger Roger</bold> rented a <bold>testitem zero dollars</bold> from <bold>Rutger</bold>."

Anyone know how to achieve this in Swift (2.2)?

Do you want it to be for just `` HTML tag or for any other tags too? — Bista, Oct 18 '16 at 04:59
Double tags are making the framework I'm using (BonMot) crash. — Rutger Huijsmans, Oct 18 '16 at 05:16
If balanced tags are making your framework crash, then the problem is the framework, not the HTML file. — Ferit, Oct 18 '16 at 05:25

score 1 · Answer 1 · answered Oct 18 '16 at 05:12

Try this, i have just made. Hope this helpful.

class Test : NSObject {
    static func removeFirstString (originString: String, removeString: String, withString: String) -> String {
        var genString = originString
        if originString.contains(removeString) {
            let range = originString.range(of: removeString)
            genString = genString.replacingOccurrences(of: removeString, with: withString, options: String.CompareOptions.anchored, range: range)
        }
        return genString
    }
}

var newString = Test.removeFirstString(originString: str, removeString: "<bold>", withString: "")

newString =  Test.removeFirstString(originString: newString, removeString: "</bold>", withString: "")

Well GJ, but I don't think it's safe. Because sometimes deleting rep. subs. unbalances HTML. For ex: `xb` your algorithm results `xb` which is unbalanced. — Ferit, Oct 18 '16 at 05:30

score 1 · Accepted Answer · answered Oct 18 '16 at 12:42

I wrote a solution using regex with the assumption that tags won't appear in nested contents more than 1 times. In other words it just cleans the double tags not more than that. You can use the same code and a recursive call to clean as many nested repeating tag as you want:

class Cleaner {

    var tags:Array<String> = [];

    init(tags:Array<String>) {
        self.tags = tags;
    }

    func cleanString(html:String) -> String {

        var res = html

        do {

            for tag in tags {

                let start = "<\(tag)>"
                let end = "</\(tag)>"

                let pattern = "\(start)(.*?)\(end)"

                let regex = try NSRegularExpression(pattern: pattern, options: NSRegularExpression.Options.caseInsensitive)

                let matches = regex.matches(in: res, options: [], range: NSRange(location: 0, length: res.utf16.count))

                var diff = 0;
                for match in matches {

                    let outer_range = NSMakeRange(match.rangeAt(0).location - diff, match.rangeAt(0).length)
                    let inner_range = NSMakeRange(match.rangeAt(1).location - diff, match.rangeAt(1).length)
                    let node = (res as NSString).substring(with: outer_range)
                    let content = (res as NSString).substring(with: inner_range)

                    // look for the starting tag in the content of the node
                    if content.range(of: start) != nil {
                        res = (res as NSString).replacingCharacters(in: outer_range, with: content);

                        //for shifting future ranges
                        diff += (node.utf16.count - content.utf16.count)
                    }
                }
            }
        }
        catch {
            print("regex was bad!")
        }

        return res
    }
}

let cleaner = Cleaner(tags: ["bold"]);
let html = "<bold><bold>Rutger</bold> Roger</bold> rented a <bold><bold>testitem</bold> zero dollars</bold> from <bold>Rutger</bold>."

let cleaned = cleaner.cleanString(html: html)
print(cleaned)
//<bold>Rutger Roger</bold> rented a <bold>testitem zero dollars</bold> from <bold>Rutger</bold>.

Remove repeating substring from string

2 Answers2