Struct FunctionSet 

pub struct FunctionSet<N: DomNavigator> { /* private fields */ }

A function set that combines built-in and custom functions.

FunctionSet<N> implements both FunctionCatalog and FunctionEvaluator<N>, allowing users to register custom XPath functions alongside the built-in ones.

Example

use xsd_schema::xpath::functions::{FunctionSet, DynamicFunctionSignature, XPathValue};
use xsd_schema::types::sequence::SequenceType;

let mut functions = FunctionSet::with_builtins();

// Register a custom function
let sig = DynamicFunctionSignature::new(
    "http://example.com/ext",
    "my-upper",
    vec![SequenceType::string()],
    SequenceType::string(),
);

functions.register(sig, |_ctx, mut args| {
    let s = args.remove(0);
    // ... implementation
    Ok(XPathValue::string("RESULT"))
});

Implementations

impl<N: DomNavigator> FunctionSet<N>

pub fn new() -> Self

Create an empty function set with no built-in functions.

Use with_builtins() to include standard XPath 2.0 functions.

pub fn with_builtins() -> Self

Create a function set with all built-in XPath 2.0 functions.

Built-in functions are looked up via the global FUNCTION_REGISTRY. Custom functions registered with register() will take precedence over built-in functions with the same signature.

pub fn register<F>( &mut self, signature: DynamicFunctionSignature, implementation: F, ) -> FunctionHandle

where F: Fn(&mut DynamicContext<'_, N>, Vec<XPathValue<N>>) -> Result<XPathValue<N>, XPathError> + Send + Sync + 'static,

Register a custom function.

The function will be available for lookup by its namespace, local name, and arity. If a function with the same signature already exists (either built-in or previously registered), the new function takes precedence.

Returns the FunctionHandle for the registered function.

Example

let sig = DynamicFunctionSignature::new(
    "http://example.com/ext",
    "double",
    vec![SequenceType::double()],
    SequenceType::double(),
);

functions.register(sig, |_ctx, mut args| {
    let val = args.remove(0);
    let d = val.as_f64().unwrap_or(0.0);
    Ok(XPathValue::double(d * 2.0))
});

pub fn custom_count(&self) -> usize

Get the number of custom functions registered.

pub fn has_custom_functions(&self) -> bool

Check if this set has any custom functions.

Trait Implementations

impl<N: DomNavigator> Debug for FunctionSet<N>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<N: DomNavigator> Default for FunctionSet<N>

fn default() -> Self

Returns the “default value” for a type.

impl<N: DomNavigator> FunctionCatalog for FunctionSet<N>

fn lookup( &self, namespace: &str, local_name: &str, arity: usize, ) -> Option<FunctionHandle>

Look up a function by namespace URI, local name, and arity.

fn get_signature( &self, handle: FunctionHandle, ) -> Option<DynamicFunctionSignature>

Get the signature for a function handle.

impl<N: DomNavigator> FunctionEvaluator<N> for FunctionSet<N>

fn eval( &self, handle: FunctionHandle, ctx: &mut DynamicContext<'_, N>, args: Vec<XPathValue<N>>, ) -> Result<XPathValue<N>, XPathError>

Evaluate a function with the given arguments.