declxml

declxml

declxml is a Rust crate that lets you declare XML trees at compile time with macros and provides deserializers with derive macros. Namespaces, attributes, and element names are checked during macro expansion.

Features

• xml! macro for inline XML AST construction.
• Pre-sorted attributes and namespaces for Exclusive C14N serialization.
• Pre-escaped literal values for safe XML output.
• Produces a lightweight AST (Element, Attr, etc.) that can be serialized directly without runtime sorting.

Assumptions

• Tag names are known at compile time.
• Namespaces and their URIs are known at compile time.
• Attribute names are known at compile time, while their values can be dynamic.

Strict Namespace Model

declxml enforces a strict namespace model to simplify canonicalization:

• Elements and attributes may be either:

  • Un-namespaced: no prefix, no associated namespace, or
  • Prefixed: a declared prefix must always be used (e.g. example:root).

• The XML default namespace form (<Element xmlns="…">) is not allowed. If you want to use a namespace, declare it in the @ns block and use the prefix consistently (example:Element).

Example

use declxml::xml;

let doc = xml! {
    // Namespace Declarations
    // Namespaces are declared once, before the root element:
    // Undeclared / unused prefix causes a compile-time error.
    @ns {
        example = "uri:ns",
        other = "uri:other",
    }

    // All documents must start with exactly one root element:
    example:root {
        // children here

        // Empty elements
        // Use a trailing semicolon (;) as shorthand for no children
        nochildren;

        // Attributes
        // Declared after the element name, before children.
        // Attributes may have prefixes or not
        example:withattrs other:id="my_id" {
            subchild other:id="other_id";
        }

        // Dynamic values
        // Wrap a Rust expression in parentheses `(…)` to inject it at runtime.
        //
        // • In attributes: the expression must be "string-like" such as
        //   `&str`, `String`, `Box<str>`, etc.
        // • In children: the expression must be either
        //   - another XML element (from `xml!`), or
        //   - any "string-like" type (e.g. `&str`, `String`, `Box<str>`, etc.).
        (custom_child)

        // Attribute with dynamic value
        custom_attr my_attr=(attr_value);
    }
};