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POHow to split this string
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copied!<p>I have some strings, entered by users, that may look like this:</p> <ol> <li>++7 <ul> <li>7++</li> <li>1++7</li> <li>1+7</li> <li>1++7+10++15+20+30++</li> </ul></li> </ol> <p>Those are to mean:</p> <ol> <li>Anything up to and including 7 <ul> <li>Anything from 7 and up</li> <li>1 and 7 and anything inbetween</li> <li>1 and 7 only</li> <li>1 to 7, 10 to 15, 20 and 30 and above</li> </ul></li> </ol> <p>I need to parse those strings into actual ranges. That is I need to create a list of objects of type Range which have a start and an end. For single items I just set the start and end to the same, and for those that are above or below, I set start or end to null. For example for the first one I would get one range which had start set to null and end set to 7.</p> <p>I currently have a kind of messy method using a regular expression to do this splitting and parsing and I want to simplify it. My problem is that I need to split on + first, and then on ++. But if I split on + first, then the ++ instances are ruined and I end up with a mess.</p> <p>Looking at those strings it should be really easy to parse them, I just can't come up with a smart way to do it. It just have to be an easier (cleaner, easier to read) way. Probably involving some easy concept I just haven't heard about before :P </p> <hr> <p>The regular expression looks like this:</p> <pre><code>private readonly Regex Pattern = new Regex(@" ( [+]{2,} )? ([^+]+) (?: (?: [+]{2,} [^+]* )* [+]{2,} ([^+]+) )? ( [+]{2,} )? ", RegexOptions.IgnorePatternWhitespace); </code></pre> <p>That is then used like this:</p> <pre><code>public IEnumerable<Range<T>> Parse(string subject, TryParseDelegate<string, T> itemParser) { if (string.IsNullOrEmpty(subject)) yield break; for (var item = RangeStringConstants.Items.Match(subject); item.Success; item = item.NextMatch()) { var startIsOpen = item.Groups[1].Success; var endIsOpen = item.Groups[4].Success; var startItem = item.Groups[2].Value; var endItem = item.Groups[3].Value; if (endItem == string.Empty) endItem = startItem; T start, end; if (!itemParser(startItem, out start) || !itemParser(endItem, out end)) continue; yield return Range.Create(startIsOpen ? default(T) : start, endIsOpen ? default(T) : end); } } </code></pre> <p>It works, but I don't think it is particularly readable or maintainable. For example changing the '+' and '++' into ',' and '-' would not be that trivial to do.</p>

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