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//! Contains high-level interface for an events-based XML emitter.
//!
//! The most important type in this module is `EventWriter` which allows writing an XML document
//! to some output stream.
pub use self::emitter::Result;
pub use self::emitter::EmitterError as Error;
pub use self::config::EmitterConfig;
pub use self::events::XmlEvent;
use self::emitter::Emitter;
use std::io::prelude::*;
mod emitter;
mod config;
pub mod events;
/// A wrapper around an `std::io::Write` instance which emits XML document according to provided
/// events.
pub struct EventWriter<W> {
sink: W,
emitter: Emitter
}
impl<W: Write> EventWriter<W> {
/// Creates a new `EventWriter` out of an `std::io::Write` instance using the default
/// configuration.
#[inline]
pub fn new(sink: W) -> EventWriter<W> {
EventWriter::new_with_config(sink, EmitterConfig::new())
}
/// Creates a new `EventWriter` out of an `std::io::Write` instance using the provided
/// configuration.
#[inline]
pub fn new_with_config(sink: W, config: EmitterConfig) -> EventWriter<W> {
EventWriter {
sink,
emitter: Emitter::new(config)
}
}
/// Writes the next piece of XML document according to the provided event.
///
/// Note that output data may not exactly correspond to the written event because
/// of various configuration options. For example, `XmlEvent::EndElement` may
/// correspond to a separate closing element or it may cause writing an empty element.
/// Another example is that `XmlEvent::CData` may be represented as characters in
/// the output stream.
pub fn write<'a, E>(&mut self, event: E) -> Result<()> where E: Into<XmlEvent<'a>> {
match event.into() {
XmlEvent::StartDocument { version, encoding, standalone } =>
self.emitter.emit_start_document(&mut self.sink, version, encoding.unwrap_or("UTF-8"), standalone),
XmlEvent::ProcessingInstruction { name, data } =>
self.emitter.emit_processing_instruction(&mut self.sink, name, data),
XmlEvent::StartElement { name, attributes, namespace } => {
self.emitter.namespace_stack_mut().push_empty().checked_target().extend(namespace.as_ref());
self.emitter.emit_start_element(&mut self.sink, name, &attributes)
}
XmlEvent::EndElement { name } => {
let r = self.emitter.emit_end_element(&mut self.sink, name);
self.emitter.namespace_stack_mut().try_pop();
r
}
XmlEvent::Comment(content) =>
self.emitter.emit_comment(&mut self.sink, content),
XmlEvent::CData(content) =>
self.emitter.emit_cdata(&mut self.sink, content),
XmlEvent::Characters(content) =>
self.emitter.emit_characters(&mut self.sink, content)
}
}
/// Returns a mutable reference to the underlying `Writer`.
///
/// Note that having a reference to the underlying sink makes it very easy to emit invalid XML
/// documents. Use this method with care. Valid use cases for this method include accessing
/// methods like `Write::flush`, which do not emit new data but rather change the state
/// of the stream itself.
pub fn inner_mut(&mut self) -> &mut W {
&mut self.sink
}
/// Unwraps this `EventWriter`, returning the underlying writer.
///
/// Note that this is a destructive operation: unwrapping a writer and then wrapping
/// it again with `EventWriter::new()` will create a fresh writer whose state will be
/// blank; for example, accumulated namespaces will be reset.
pub fn into_inner(self) -> W {
self.sink
}
}