xml/
writer.rs

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, Result};
8pub use self::events::XmlEvent;
9
10use self::emitter::Emitter;
11
12use std::io::prelude::*;
13
14mod config;
15mod emitter;
16pub mod events;
17
18/// A wrapper around an `std::io::Write` instance which emits XML document according to provided
19/// events.
20pub struct EventWriter<W> {
21    sink: W,
22    emitter: Emitter,
23}
24
25impl<W: Write> EventWriter<W> {
26    /// Creates a new `EventWriter` out of an `std::io::Write` instance using the default
27    /// configuration.
28    #[inline]
29    pub fn new(sink: W) -> Self {
30        Self::new_with_config(sink, EmitterConfig::new())
31    }
32
33    /// Creates a new `EventWriter` out of an `std::io::Write` instance using the provided
34    /// configuration.
35    #[inline]
36    pub fn new_with_config(sink: W, config: EmitterConfig) -> Self {
37        Self {
38            sink,
39            emitter: Emitter::new(config),
40        }
41    }
42
43    /// Writes the next piece of XML document according to the provided event.
44    ///
45    /// Note that output data may not exactly correspond to the written event because
46    /// of various configuration options. For example, `XmlEvent::EndElement` may
47    /// correspond to a separate closing element or it may cause writing an empty element.
48    /// Another example is that `XmlEvent::CData` may be represented as characters in
49    /// the output stream.
50    pub fn write<'a, E>(&mut self, event: E) -> Result<()> where E: Into<XmlEvent<'a>> {
51        match event.into() {
52            XmlEvent::StartDocument { version, encoding, standalone } =>
53                self.emitter.emit_start_document(&mut self.sink, version, encoding.unwrap_or("UTF-8"), standalone),
54            XmlEvent::ProcessingInstruction { name, data } =>
55                self.emitter.emit_processing_instruction(&mut self.sink, name, data),
56            XmlEvent::StartElement { name, attributes, namespace } => {
57                self.emitter.namespace_stack_mut().push_empty().checked_target().extend(namespace.as_ref());
58                self.emitter.emit_start_element(&mut self.sink, name, &attributes)
59            },
60            XmlEvent::EndElement { name } => {
61                let r = self.emitter.emit_end_element(&mut self.sink, name);
62                self.emitter.namespace_stack_mut().try_pop();
63                r
64            },
65            XmlEvent::Comment(content) => self.emitter.emit_comment(&mut self.sink, content),
66            XmlEvent::CData(content) => self.emitter.emit_cdata(&mut self.sink, content),
67            XmlEvent::Characters(content) => self.emitter.emit_characters(&mut self.sink, content),
68            XmlEvent::RawCharacters(content) => self.emitter.emit_raw_characters(&mut self.sink, content),
69            XmlEvent::Doctype(content) => self.emitter.emit_raw_characters(&mut self.sink, content),
70        }
71    }
72
73    /// Returns a mutable reference to the underlying `Writer`.
74    ///
75    /// Note that having a reference to the underlying sink makes it very easy to emit invalid XML
76    /// documents. Use this method with care. Valid use cases for this method include accessing
77    /// methods like `Write::flush`, which do not emit new data but rather change the state
78    /// of the stream itself.
79    pub fn inner_mut(&mut self) -> &mut W {
80        &mut self.sink
81    }
82
83    /// Returns an immutable reference to the underlying `Writer`.
84    pub fn inner_ref(&self) -> &W {
85        &self.sink
86    }
87
88    /// Unwraps this `EventWriter`, returning the underlying writer.
89    ///
90    /// Note that this is a destructive operation: unwrapping a writer and then wrapping
91    /// it again with `EventWriter::new()` will create a fresh writer whose state will be
92    /// blank; for example, accumulated namespaces will be reset.
93    pub fn into_inner(self) -> W {
94        self.sink
95    }
96}
xml/writer.rs

xml/
writer.rs
