Our goal is to use string pattern matching in easy-swifty way:
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// Credit card number
let string = "4916474932438684"
// Check if it's Visa
if string =~ "^4[0-9]{6,}$" {
/* */
}
Pattern matching with regular expression is supported by range function with .regularExpression options flag:
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if string.range(of: "^4[0-9]{6,}$", options: [.regularExpression]) {
// string is matches /^4[0-9]{6,}$/
}
Let’s wrap this call into String’s extension helper function called matches:
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/// String extensions
extension String {
/// Returns true if `String` matches regex `pattern`.
/// - parameter pattern: pattern to search
func matches(_ pattern: String) -> Bool {
range(of: pattern, options: [.regularExpression]) != nil
}
}
Then we already can shortify matching call with our matches function:
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if string.matches("^4[0-9]{6,}$") {
/* */
}
The last step is to create infix operator for our function:
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/// String regex pattern matching operator
infix operator =~
/// Returns true if `string` matches regular expression `pattern`.
/// - parameter string: string to test
/// - parameter pattern: pattern to match
func =~ (string: String, pattern: String) -> Bool {
string.matches(pattern)
}
// Usage:
if "cat" =~ "[cb]at" {
/* */
}