Node

Represents a parentless XML element.

Nodes can be shared or inserted into different trees. Serialization derives namespace declarations from each node rather than from parent pointers.

Constructor

`Node tag ...items :namespace? :prefix? :attrs?`

Creates an element, optionally with attributes and children.

Parameters:

Name	Type	Description
`tag`	`Str`	Local element name
`items`	`*`	An `Attr` becomes an attribute; anything else becomes a child
`namespace`	`str?`	Namespace URI
`prefix`	`str?`	Preferred namespace prefix
`attrs`	`Dict?`	Unnamespaced attributes; keys may be `Sym` or `Str`, values must be `Str`

Returns: Node.

Errors:

TypeError if attrs is not a Dict, or one of its values is not a Str.

Children are not type-checked here, matching children.push; a tree containing anything other than Node and Str children is rejected by verify and by serialization.

attrs is applied before any positional Attr, regardless of where the keyword appears in the call.

let item = Node "item" namespace: "urn:inventory" prefix: "inv"

let disk = Node disk
  attrs:
    type: file
    device: disk
  - $ Node driver attrs: {name: "qemu", type: "qcow2"}
  - $ Node source
      attrs:
        file: /tmp/disk.qcow2

Fields

`tag`

Mutable local element name.

`namespace`

Mutable namespace URI as a Str, or nil for no namespace.

`prefix`

Mutable preferred prefix as a Str, or nil.

`qname`

Read-only qualified name formed from prefix and tag.

`attrs`

Mutable array-like view of Attr objects in document order.

The view supports indexed assignment and the Array mutation methods push, insert, pop, delete, and clear. Duplicate expanded names can exist temporarily, but verify and serialization reject them.

let node = Node "item"
node.attrs.push (Attr "id" "123")
node.attrs[0].value = "456"

`children`

Mutable array-like view of child Node and Str values in document order.

The view supports indexed assignment and the Array mutation methods push, insert, pop, delete, and clear.

Iterating a node iterates this view directly.

`namespaces`

Mutable dict containing the complete effective namespace snapshot for the node. Keys are prefix strings; "" is the default namespace. The reserved xml binding is included.

Parsed descendants retain inherited bindings in their own snapshots, so they can be detached and serialized independently.

Methods

`attr name :namespace? :default? :else?`

Gets the first attribute matching an expanded name.

Parameters:

Name	Type	Description
`name`	`Str`	Local attribute name
`namespace`	`str?`	Namespace URI
`default`		Value returned when absent
`else`		Callable evaluated when absent

Returns: The attribute value, nil, or the selected fallback.

let id = node.attr "id" namespace: "urn:inventory"

`set_attr name value :namespace? :prefix?`

Updates the first matching attribute or appends one.

An omitted prefix mutates the existing attribute's value in place. An explicit prefix, including prefix: nil, replaces the matching attribute because attribute identity fields are immutable.

Parameters:

Name	Type	Description
`name`	`Str`	Local attribute name
`value`	`Str`	Attribute value
`namespace`	`str?`	Namespace URI
`prefix`	`str?`	Preferred namespace prefix

Returns: nil.

`delete_attr name :namespace?`

Deletes all attributes matching an expanded name.

Parameters:

Name	Type	Description
`name`	`Str`	Local attribute name
`namespace`	`str?`	Namespace URI

Returns: Bool, whether an attribute was deleted.

`push child`

Appends a child.

Parameters:

Name	Type	Description
`child`	`Node`\|`Str`	Child value

Returns: nil.

`traverse`

Returns a depth-first, parent-first iterator over the node and its descendants.

Returns: An iterator of nodes and text values in document order.

Operators

String indexing accesses unnamespaced attributes. Assignment updates the first match or appends a new attribute. Integer indexing reads children, including negative indexes. Use attr, set_attr, and delete_attr for namespaced attributes.

let node = Node "item"
node["id"] = "123"
assert_eq $node["id"] "123"
node.push "content"
assert_eq $node[0] "content"