XercesSwiftXcode: Xerces binding for Swift as Xcode project (experimental)

This is an experimental project in the form of an Xcode project that uses the Xerces-C++ XML parser as an XML parser. Why Xerces? Xerces is an important parser for XML, e.g. Java comes with a Java version of it, and libxml2 does not fully support W3C schema for validation, but Xerces does.

The project includes a (very incomplete) binding to Xerces in form of a SAX-like interface. As the C++ binding to Swift is not ready yet for production, it uses Objective-C as an intermediate for the binding. Xerces-C++ is included here in compiled form as a dynamic library for macOS (Intel). Replace this library by one for your platform form XercesBuild, or, If you do not want to one of those this binaries, please see the same repository for build instructions for Xerces-C++ or go directly to the Xerces-C++ XML parser website. The following main.swift is included in the project that succesfully executes:

import Foundation

class MyXMLParseConsumer: XMLParseConsumer {
    
    override func startElement(name: String) {
        print("start element: \(name)")
    }
    
}

if CommandLine.arguments.count != 2 {
    print("ERROR: need exactly one argument = path XML file to parse")
}
else {
    let parseConsumer = MyXMLParseConsumer()
    let parser = XercesParser(withParseConsumer: parseConsumer)
    let returnCode = parser.parse(fromPath: CommandLine.arguments[1])
    print("return code: \(returnCode)")
}

Given the path to an XML file as the argument, it prints the element names for each element it encounters while parsing.

(Note that the inclusion of the C++ header files from Xerces-C++ is better solved in the repository XercesSwift.)

The goal is just to use Xerces as a parser in a SAX-like manner including validation during parsing (according to a DTD or a W3C schema, less Relax NG for which libxml2 would be a better choice), not using any DOM built by Xerces. Of course, to make this binding to Xerces-C++ usable in practice, some more work would be necessary:

• Make the binding more complete.
• Make the C++ API of the binding more appropriate (currently it just a textual argument-passing API on the C++ level, which stems from a simple C++ SAX parsing example).
• Maybe avoid having all those include files from Xerces somehow?
• Maybe include the whole Xerces source code and let Xerces be built as part of the project?
• Make a separate package with just the statemant of the SAX interface (class XMLParseConsumer in the above code) to be able to easily switch parsers in a project (e.g. be able to switch form Xerces to libxml2 or the way around).

But the first next step should be to make a project for the Swift Package Manager from it. For this, the following repository exists, which is a Swift package, but not runnable yet: XercesSwift.

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Legal notice: Usage of any of the included material is to your own risk. The Xerces-C++ source is from https://xerces.apache.org/xerces-c/ and is used under the Apache 2 license.