XMLNode

A lightweight but powful package to encode, decode and traverse XML

0. API

Refer to the comments:

    public final class XMLNode:NSObject {
        public var name = ""
        public var attributes = [String:String]()
        public var value = ""
        public var children = [XMLNode]()
        public weak var parent:XMLNode?
        //build a node from XML
        public static func node(_ string:String)->XMLNode?{}
        //turn a node to XML
        public var string: String{get}
        /*
            depth first traverse
            Regex pattern: `|?(name(/other)*([key(=value(/other)*)?])?)+`
            Instructions:
            |: matches from current node
            /: or
            name: tag name
            key: keys in attributes
            value: values in attributes
        */
        public subscript(path: String) -> XMLNode? {}
        public var root:XMLNode{get}
    }

1. Build a node from XML

Take this XML as an example:

    <animals>
        <cats>
            <cat age="2" color="lightgray">Tinna</cat>
            <cat height="15" color="darkgray">Rose</cat>
            <cat weight="2.4" color="yellow">Caesar</cat>
        </cats>
        <dogs>
            <dog age="4" color="brown">Villy</dog>
            <dog height="46" color="white">Spot</dog>
            <dog weight="18" color="yellow">Betty</dog>
        </dogs>
    </animals>

    //We buile a node from the XML and use it later
    let node = XMLNode.node(str)

2. Turn a node to XML

    //decode previous node
    print(node.string)

Here's the result:  

    <animals>
        <cats>
            <cat color="lightgray" age="2">Tinna</cat>
            <cat color="darkgray" height="15">Rose</cat>
            <cat color="yellow" weight="2.4">Caesar</cat>
        </cats>
        <dogs>
            <dog color="brown" age="4">Villy</dog>
            <dog color="white" height="46">Spot</dog>
            <dog color="yellow" weight="18">Betty</dog>
        </dogs>
    </animals>

3. Traverse

Regex pattern: `|?(name(/other)*([key(=value(/other)*)?])?)+`  
Instructions:  
`|`: matches from current node  
`/`: or  
`name`: tag name  
`key`: keys in attributes  
`value`: values in attributes  

    print(node["cats.cat"]?.string ?? "nil")
    print(node["|cats.cat"]?.string ?? "nil")
    print(node["|animals.cats.cat"]?.string ?? "nil")
    print(node["cat/dog[height]"]?.string ?? "nil")
    print(node["cats/dogs.cat/dog[color=white/brown]"]?.string ?? "nil")

Here's the result: 

    <cat age="2" color="lightgray">Tinna</cat>
    nil
    <cat age="2" color="lightgray">Tinna</cat>
    <cat height="15" color="darkgray">Rose</cat>
    <dog height="46" color="white">Spot</dog>