It’s time to ask the all important question: what’s the point? We now have a properly defined parser type, one that can parse efficiently and incrementally, but does it give us anything new over existing tools?
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The interface for mutating substrings is the same as the interface for mutating strings, but we’ll get a bit of a performance boost by working with a view into the string instead of a copy.
We still have the restriction that the entire String must be in memory, which means parsing a very large String isn’t going to be efficient, but the optimizations we’ve made so far were very low-hanging and already buy us a lot, so let’s kick that can a bit down the road.
This article demonstrates that parsing can be a great alternative to validating. When validating you often check for certain requirements of your values, but don’t have any record of that check in your types. Whereas parsing allows you to upgrade the types to something more restrictive so that you cannot misuse the value later on.
In this free episode of Swift talk, Chris and Florian discuss various techniques for parsing strings as a means to process a ledger file. It contains a good overview of various parsing techniques, including parser grammars.
In this free episode of Swift talk, Chris and Florian discuss how to efficiently use Swift strings, and in particular how to use the Substring type to prevent unnecessary copies of large strings.We write a simple CSV parser as an example demonstrating how to work with Swift’s String and Substring types.
Swift contributor Michael Ilseman lays out some potential future directions for Swift’s string consumption API. This could be seen as a “Swiftier” way of doing what the Scanner type does today, but possibly even more powerful.
This question on the Swift forums brings up an interesting discussion on how to best handle large files (hundreds of megabytes and millions of lines) in Swift. The thread contains lots of interesting tips on how to improve performance, and contains some hope of future standard library changes that may help too.
Official documentation for the Scanner type by Apple. Although the type hasn’t (yet) been updated to take advantage of Swift’s modern features, it is still a very powerful API that is capable of parsing complex text formats.
A nice, concise article covering the Scanner type, including a tip of how to extend the Scanner so that it is a bit more “Swifty”. Take note that this article was written before NSScanner was renamed to just Scanner in Swift 3.
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