Kanna is a Swift library used for parsing HTML and XML. It provides a way to query and manipulate the structure of documents. While Kanna itself does not provide regular expression (regex) capabilities directly, Swift has built-in support for regular expressions through its NSRegularExpression class. You can use this in conjunction with Kanna to perform pattern matching on the text content extracted from HTML or XML documents.
Here's a basic example of how you might use regular expressions with Kanna in Swift:
import Kanna
let html = """
<html>
<body>
<p>Email: example@example.com</p>
<p>Phone: +123-456-7890</p>
</body>
</html>
"""
do {
// Parse the HTML
let doc = try HTML(html: html, encoding: .utf8)
// Extract all paragraph (<p>) elements
for p in doc.xpath("//p") {
// Get the content of each paragraph
if let text = p.text {
// Define a regular expression to find email addresses
let regex = try NSRegularExpression(pattern: "[A-Z0-9._%+-]+@[A-Z0-9.-]+\\.[A-Z]{2,}", options: .caseInsensitive)
// Search for matches in the paragraph text
let matches = regex.matches(in: text, options: [], range: NSRange(location: 0, length: text.utf16.count))
// Print out the matches
for match in matches {
if let range = Range(match.range, in: text) {
let matchedString = String(text[range])
print("Found email: \(matchedString)")
}
}
}
}
} catch let error {
print("Error parsing HTML: \(error)")
}
In this example, we first parse an HTML string with Kanna. Then, we extract all the paragraph elements and use the NSRegularExpression class to define a regex pattern for finding email addresses. We apply this pattern to the text content of each paragraph and print out any matches we find.
Remember that while regular expressions can be powerful for certain tasks, they may not be the best tool for parsing HTML or XML due to the complex and nested nature of these types of documents. It's generally more reliable to use proper HTML/XML parsing libraries like Kanna to navigate and query the document structure, and use regular expressions for simple text pattern matching within that content.
