1//! Contains high-level interface for an events-based XML emitter.
2//!
3//! The most important type in this module is `EventWriter` which allows writing an XML document
4//! to some output stream.
5
6pub use self::config::EmitterConfig;
7pub use self::emitter::EmitterError as Error;
8pub use self::emitter::Result;
9pub use self::events::XmlEvent;
10
11use self::emitter::Emitter;
12
13use std::io::prelude::*;
14
15mod config;
16mod emitter;
17pub mod events;
18
19/// A wrapper around an `std::io::Write` instance which emits XML document according to provided
20/// events.
21pub struct EventWriter<W> {
22 sink: W,
23 emitter: Emitter,
24}
25
26impl<W: Write> EventWriter<W> {
27 /// Creates a new `EventWriter` out of an `std::io::Write` instance using the default
28 /// configuration.
29 #[inline]
30 pub fn new(sink: W) -> EventWriter<W> {
31 EventWriter::new_with_config(sink, EmitterConfig::new())
32 }
33
34 /// Creates a new `EventWriter` out of an `std::io::Write` instance using the provided
35 /// configuration.
36 #[inline]
37 pub fn new_with_config(sink: W, config: EmitterConfig) -> EventWriter<W> {
38 EventWriter {
39 sink,
40 emitter: Emitter::new(config),
41 }
42 }
43
44 /// Writes the next piece of XML document according to the provided event.
45 ///
46 /// Note that output data may not exactly correspond to the written event because
47 /// of various configuration options. For example, `XmlEvent::EndElement` may
48 /// correspond to a separate closing element or it may cause writing an empty element.
49 /// Another example is that `XmlEvent::CData` may be represented as characters in
50 /// the output stream.
51 pub fn write<'a, E>(&mut self, event: E) -> Result<()> where E: Into<XmlEvent<'a>> {
52 match event.into() {
53 XmlEvent::StartDocument { version, encoding, standalone } =>
54 self.emitter.emit_start_document(&mut self.sink, version, encoding.unwrap_or("UTF-8"), standalone),
55 XmlEvent::ProcessingInstruction { name, data } =>
56 self.emitter.emit_processing_instruction(&mut self.sink, name, data),
57 XmlEvent::StartElement { name, attributes, namespace } => {
58 self.emitter.namespace_stack_mut().push_empty().checked_target().extend(namespace.as_ref());
59 self.emitter.emit_start_element(&mut self.sink, name, &attributes)
60 }
61 XmlEvent::EndElement { name } => {
62 let r = self.emitter.emit_end_element(&mut self.sink, name);
63 self.emitter.namespace_stack_mut().try_pop();
64 r
65 }
66 XmlEvent::Comment(content) => self.emitter.emit_comment(&mut self.sink, content),
67 XmlEvent::CData(content) => self.emitter.emit_cdata(&mut self.sink, content),
68 XmlEvent::Characters(content) => self.emitter.emit_characters(&mut self.sink, content),
69 }
70 }
71
72 /// Returns a mutable reference to the underlying `Writer`.
73 ///
74 /// Note that having a reference to the underlying sink makes it very easy to emit invalid XML
75 /// documents. Use this method with care. Valid use cases for this method include accessing
76 /// methods like `Write::flush`, which do not emit new data but rather change the state
77 /// of the stream itself.
78 pub fn inner_mut(&mut self) -> &mut W {
79 &mut self.sink
80 }
81
82 /// Unwraps this `EventWriter`, returning the underlying writer.
83 ///
84 /// Note that this is a destructive operation: unwrapping a writer and then wrapping
85 /// it again with `EventWriter::new()` will create a fresh writer whose state will be
86 /// blank; for example, accumulated namespaces will be reset.
87 pub fn into_inner(self) -> W {
88 self.sink
89 }
90}
91