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;
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) -> Self {
31        Self::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) -> Self {
38        Self {
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    /// Returns an immutable reference to the underlying `Writer`.
83    pub fn inner_ref(&self) -> &W {
84        &self.sink
85    }
86
87    /// Unwraps this `EventWriter`, returning the underlying writer.
88    ///
89    /// Note that this is a destructive operation: unwrapping a writer and then wrapping
90    /// it again with `EventWriter::new()` will create a fresh writer whose state will be
91    /// blank; for example, accumulated namespaces will be reset.
92    pub fn into_inner(self) -> W {
93        self.sink
94    }
95}
xml/writer.rs

xml/
writer.rs
