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I'm obtaining a response to an HTTP POST request with the code

let task = NSURLSession.sharedSession().dataTaskWithRequest(request) {data, response, error in

if error != nil {
println("error=\(error)")
return
}
// Get the response to the HTTP POST
var responseString = NSString(data: data, encoding: NSUTF8StringEncoding)!}
task.resume()

I tried to define two regular expressions

let regex0: NSRegularExpression = NSRegularExpression(pattern: "<b>District Representatives:</b>", options: NSRegularExpressionOptions.DotMatchesLineSeparators, error: nil)!

let regex1: NSRegularExpression = NSRegularExpression(pattern: "\\A.*<b>District Representatives:</b>.*href=\"http://www\.sec\.state\.ma\.us/ele/eledist/con11idx\.htm#D[1-9]\" target=\"_blank\">(.*?)</a>.*href=\"http://www\.sec\.state\.ma\.us/ele/eledist/sen11idx\.htm#[0-9]{0,5}[a-z]{1,20}\" target=\"_blank\">(.*?)</a>.*\"http://www\.sec\.state\.ma\.us/ele/eledist/reps11idx\.htm#[a-z]{1,13}[0-9]{0,2}\" target=\"_blank\">(.*?)</a>.*\\z", options: NSRegularExpressionOptions.DotMatchesLineSeparators, error: nil)!

But Xcode gives me the error message "Expected expression" on the definition of regex1.

I want to test whether responseString is matched by regex0. I tried using

var numberOfMatches: Int = regex0.numberOfMatchesInString(responseString, options:nil, range: (NSMakeRange(0, responseString.length)))

but I got the error message "Use of unresolved identifier responseString"

I'd like to know how to test for the success of a regular expression match. In this case, I could just test whether responseString contains my test string. That seems to work nicely with Swift Strings, but I can't get it to work with an NSString.

I think the pattern in my regex1 regular expression is OK, because I tested the equivalent pattern in TextWrangler. The pattern I used there was

(?s)\A.*<b>District Representatives:</b>.*href="http://www\.sec\.state\.ma\.us/ele/eledist/con11idx\.htm#D[1-9]" target="_blank">(.*?)</a>.*href="http://www\.sec\.state\.ma\.us/ele/eledist/sen11idx\.htm#[0-9]{0,5}[a-z]{1,20}" target="_blank">(.*?)</a>.*"http://www\.sec\.state\.ma\.us/ele/eledist/reps11idx\.htm#[a-z]{1,13}[0-9]{0,2}" target="_blank">(.*?)</a>.*\z

The only (intentional) differences are that in the Swift literal, all the Double-Quotes and Backslashes had to be escaped with a backslash and the TextWrangler pattern starts with (?s) which is the equivalent of NSRegularExpressionOptions.DotMatchesLineSeparators.

I wanted to use regex1 to modify responseString as follows

responseString.replaceMatchesInString(options: nil, range: NSMakeRange(0, responseString.length), withTemplate template: "$1\t$2\t$3")

But that didn't work either.

I naively thought that since I've been using regular expressions for 30 years, that part would be easy. Apparently not.

David Rosenberg
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1 Answers1

0

Your regex1 is missing double escapes on the literal dots (see www\.sec\.state\.ma\.us).

The correct regex1 declaration will be

@"\\A.*<b>District Representatives:</b>.*href=\"http://www\\.sec\\.state\\.ma\\.us/ele/eledist/con11idx\\.htm#D[1-9]\" target=\"_blank\">(.*?)</a>.*href=\"http://www\\.sec\\.state\\.ma\\.us/ele/eledist/sen11idx\\.htm#[0-9]{0,5}[a-z]{1,20}\" target=\"_blank\">(.*?)</a>.*\"http://www\\.sec\\.state\\.ma\\.us/ele/eledist/reps11idx\\.htm#[a-z]{1,13}[0-9]{0,2}\" target=\"_blank\">(.*?)</a>.*\\z"

You get Use of unresolved identifier responseString probably because you declared responseString outside the method where you declare and use numberOfMatches.

Wiktor Stribiżew
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  • Thank you. That fix eliminated the error message on the definition of regex1. The "Use of unresolved identifier responseString" problem seems to be at the root of a lot of my remaining difficulties. I think that I have to resolve that before I get back to working on regular expression problems. – David Rosenberg May 29 '15 at 13:21
  • Please post your complete code with the regexps and the reponseString, or if it is too long, use [pastebin](http://pastebin.com) – Wiktor Stribiżew May 29 '15 at 13:33
  • Plese have a look at [this question](http://stackoverflow.com/a/28997222/3832970) answer. Does that help? – Wiktor Stribiżew May 29 '15 at 15:49
  • Thank you @stribizhev for your assistance. I put the current program (minus some junk) on Pastenbin at http://pastebin.com/HwNLxbi9 I added comments about my current stumbling blocks and the program has comments describing parts I haven't written yet. In the question at http://stackoverflow.com/questions/30418955/sample-swift-program-to-get-file-paths-read-write-records-do-html-post-sh I tried to give a template of my program (excluding the part that does the useful work). Right now, my main problem is that I want to have a synchronous loop and Xcode wants me to have asynchronous tasks. – David Rosenberg May 30 '15 at 03:35