element.rs

  1//! Provides an `Element` type, which represents DOM nodes, and a builder to create them with.
  2
  3use std::io:: Write;
  4use std::collections::{btree_map, BTreeMap};
  5
  6use std::str;
  7use std::rc::Rc;
  8use std::borrow::Cow;
  9
 10use error::{Error, ErrorKind, Result};
 11
 12use quick_xml::reader::Reader as EventReader;
 13use quick_xml::events::{Event, BytesStart};
 14
 15use std::io::BufRead;
 16
 17use std::str::FromStr;
 18
 19use std::slice;
 20
 21use convert::{IntoElements, IntoAttributeValue, ElementEmitter};
 22use namespace_set::NamespaceSet;
 23
 24/// Escape XML text
 25pub fn write_escaped<W: Write>(writer: &mut W, input: &str) -> Result<()> {
 26    for c in input.chars() {
 27        match c {
 28            '&' => write!(writer, "&amp;")?,
 29            '<' => write!(writer, "&lt;")?,
 30            '>' => write!(writer, "&gt;")?,
 31            '\'' => write!(writer, "&apos;")?,
 32            '"' => write!(writer, "&quot;")?,
 33            _ => write!(writer, "{}", c)?,
 34        }
 35    }
 36
 37    Ok(())
 38}
 39
 40/// A node in an element tree.
 41#[derive(Clone, Debug, PartialEq, Eq)]
 42pub enum Node {
 43    /// An `Element`.
 44    Element(Element),
 45    /// A text node.
 46    Text(String),
 47}
 48
 49impl Node {
 50    /// Turns this into an `Element` if possible, else returns None.
 51    ///
 52    /// # Examples
 53    ///
 54    /// ```rust
 55    /// use minidom::Node;
 56    ///
 57    /// let elm = Node::Element("<meow />".parse().unwrap());
 58    /// let txt = Node::Text("meow".to_owned());
 59    ///
 60    /// assert_eq!(elm.as_element().unwrap().name(), "meow");
 61    /// assert_eq!(txt.as_element(), None);
 62    /// ```
 63    pub fn as_element(&self) -> Option<&Element> {
 64        match *self {
 65            Node::Element(ref e) => Some(e),
 66            Node::Text(_) => None,
 67        }
 68    }
 69
 70    /// Turns this into a `String` if possible, else returns None.
 71    ///
 72    /// # Examples
 73    ///
 74    /// ```rust
 75    /// use minidom::Node;
 76    ///
 77    /// let elm = Node::Element("<meow />".parse().unwrap());
 78    /// let txt = Node::Text("meow".to_owned());
 79    ///
 80    /// assert_eq!(elm.as_text(), None);
 81    /// assert_eq!(txt.as_text().unwrap(), "meow");
 82    /// ```
 83    pub fn as_text(&self) -> Option<&str> {
 84        match *self {
 85            Node::Element(_) => None,
 86            Node::Text(ref s) => Some(s),
 87        }
 88    }
 89
 90    fn write_to_inner<W: Write>(&self, writer: &mut W) -> Result<()>{
 91        match *self {
 92            Node::Element(ref elmt) => elmt.write_to_inner(writer)?,
 93            Node::Text(ref s) => write_escaped(writer, s)?,
 94        }
 95
 96        Ok(())
 97    }
 98}
 99
100#[derive(Clone, PartialEq, Eq, Debug)]
101/// A struct representing a DOM Element.
102pub struct Element {
103    prefix: Option<String>,
104    name: String,
105    namespaces: Rc<NamespaceSet>,
106    attributes: BTreeMap<String, String>,
107    children: Vec<Node>,
108}
109
110impl<'a> From<&'a Element> for String {
111    fn from(elem: &'a Element) -> String {
112        let mut writer = Vec::new();
113        elem.write_to(&mut writer).unwrap();
114        String::from_utf8(writer).unwrap()
115    }
116}
117
118
119impl FromStr for Element {
120    type Err = Error;
121
122    fn from_str(s: &str) -> Result<Element> {
123        let mut reader = EventReader::from_str(s);
124        Element::from_reader(&mut reader)
125    }
126}
127
128impl Element {
129    fn new<NS: Into<NamespaceSet>>(name: String, prefix: Option<String>, namespaces: NS, attributes: BTreeMap<String, String>, children: Vec<Node>) -> Element {
130        Element {
131            prefix, name,
132            namespaces: Rc::new(namespaces.into()),
133            attributes: attributes,
134            children: children,
135        }
136    }
137
138    /// Return a builder for an `Element` with the given `name`.
139    ///
140    /// # Examples
141    ///
142    /// ```rust
143    /// use minidom::Element;
144    ///
145    /// let elem = Element::builder("name")
146    ///                    .ns("namespace")
147    ///                    .attr("name", "value")
148    ///                    .append("inner")
149    ///                    .build();
150    ///
151    /// assert_eq!(elem.name(), "name");
152    /// assert_eq!(elem.ns(), Some("namespace".to_owned()));
153    /// assert_eq!(elem.attr("name"), Some("value"));
154    /// assert_eq!(elem.attr("inexistent"), None);
155    /// assert_eq!(elem.text(), "inner");
156    /// ```
157    pub fn builder<S: AsRef<str>>(name: S) -> ElementBuilder {
158        let (prefix, name) = split_element_name(name).unwrap();
159        ElementBuilder {
160            root: Element::new(name, prefix, None, BTreeMap::new(), Vec::new()),
161            namespaces: Default::default(),
162        }
163    }
164
165    /// Returns a bare minimum `Element` with this name.
166    ///
167    /// # Examples
168    ///
169    /// ```rust
170    /// use minidom::Element;
171    ///
172    /// let bare = Element::bare("name");
173    ///
174    /// assert_eq!(bare.name(), "name");
175    /// assert_eq!(bare.ns(), None);
176    /// assert_eq!(bare.attr("name"), None);
177    /// assert_eq!(bare.text(), "");
178    /// ```
179    pub fn bare<S: Into<String>>(name: S) -> Element {
180        Element {
181            prefix: None,
182            name: name.into(),
183            namespaces: Rc::new(NamespaceSet::default()),
184            attributes: BTreeMap::new(),
185            children: Vec::new(),
186        }
187    }
188
189    /// Returns a reference to the name of this element.
190    pub fn name(&self) -> &str {
191        &self.name
192    }
193
194    /// Returns a reference to the namespace of this element, if it has one, else `None`.
195    pub fn ns(&self) -> Option<String> {
196        self.namespaces.get(&self.prefix)
197    }
198
199    /// Returns a reference to the value of the given attribute, if it exists, else `None`.
200    pub fn attr(&self, name: &str) -> Option<&str> {
201        if let Some(value) = self.attributes.get(name) {
202            return Some(value)
203        }
204        None
205    }
206
207    /// Returns an iterator over the attributes of this element.
208    ///
209    /// # Example
210    ///
211    /// ```rust
212    /// use minidom::Element;
213    ///
214    /// let elm: Element = "<elem a=\"b\" />".parse().unwrap();
215    ///
216    /// let mut iter = elm.attrs();
217    ///
218    /// assert_eq!(iter.next().unwrap(), ("a", "b"));
219    /// assert_eq!(iter.next(), None);
220    /// ```
221    pub fn attrs(&self) -> Attrs {
222        Attrs {
223            iter: self.attributes.iter(),
224        }
225    }
226
227    /// Returns an iterator over the attributes of this element, with the value being a mutable
228    /// reference.
229    pub fn attrs_mut(&mut self) -> AttrsMut {
230        AttrsMut {
231            iter: self.attributes.iter_mut(),
232        }
233    }
234
235    /// Modifies the value of an attribute.
236    pub fn set_attr<S: Into<String>, V: IntoAttributeValue>(&mut self, name: S, val: V) {
237        let name = name.into();
238        let val = val.into_attribute_value();
239
240        if let Some(value) = self.attributes.get_mut(&name) {
241            *value = val.expect("removing existing value via set_attr, this is not yet supported (TODO)"); // TODO
242            return;
243        }
244
245        if let Some(val) = val {
246            self.attributes.insert(name, val);
247        }
248    }
249
250    /// Returns whether the element has the given name and namespace.
251    ///
252    /// # Examples
253    ///
254    /// ```rust
255    /// use minidom::Element;
256    ///
257    /// let elem = Element::builder("name").ns("namespace").build();
258    ///
259    /// assert_eq!(elem.is("name", "namespace"), true);
260    /// assert_eq!(elem.is("name", "wrong"), false);
261    /// assert_eq!(elem.is("wrong", "namespace"), false);
262    /// assert_eq!(elem.is("wrong", "wrong"), false);
263    /// ```
264    pub fn is<N: AsRef<str>, NS: AsRef<str>>(&self, name: N, namespace: NS) -> bool {
265        self.name == name.as_ref() &&
266            self.namespaces.has(&self.prefix, namespace)
267    }
268
269    /// Parse a document from an `EventReader`.
270    pub fn from_reader<R: BufRead>(reader: &mut EventReader<R>) -> Result<Element> {
271        let mut buf = Vec::new();
272
273        let root: Element = loop {
274            let e = reader.read_event(&mut buf)?;
275            match e {
276                Event::Empty(ref e) | Event::Start(ref e) => {
277                    break build_element(e)?;
278                },
279                Event::Eof => {
280                    bail!(ErrorKind::EndOfDocument);
281                },
282                _ => () // TODO: may need more errors
283            }
284        };
285
286        let mut stack = vec![root];
287
288        loop {
289            match reader.read_event(&mut buf)? {
290                Event::Empty(ref e) => {
291                    let elem = build_element(e)?;
292                    // Since there is no Event::End after, directly append it to the current node
293                    stack.last_mut().unwrap().append_child(elem);
294                },
295                Event::Start(ref e) => {
296                    let elem = build_element(e)?;
297                    stack.push(elem);
298                },
299                Event::End(ref e) => {
300                    if stack.len() <= 1 {
301                        break;
302                    }
303                    let elem = stack.pop().unwrap();
304                    if let Some(to) = stack.last_mut() {
305                        if elem.name().as_bytes() != e.name() {
306                            bail!(ErrorKind::InvalidElementClosed);
307                        }
308                        to.append_child(elem);
309                    }
310                },
311                Event::Text(s) | Event::CData(s) => {
312                    let text = s.unescape_and_decode(reader)?;
313                    if text != "" {
314                        let mut current_elem = stack.last_mut().unwrap();
315                        current_elem.append_text_node(text);
316                    }
317                },
318                Event::Eof => {
319                    break;
320                },
321                _ => (), // TODO: may need to implement more
322            }
323        }
324        Ok(stack.pop().unwrap())
325    }
326
327    /// Output a document to a `Writer`.
328    pub fn write_to<W: Write>(&self, writer: &mut W) -> Result<()> {
329        write!(writer, "<?xml version=\"1.0\" encoding=\"utf-8\"?>")?;
330        self.write_to_inner(writer)
331    }
332
333    /// Like `write_to()` but without the `<?xml?>` prelude
334    pub fn write_to_inner<W: Write>(&self, writer: &mut W) -> Result<()> {
335        let name = match &self.prefix {
336            &None => Cow::Borrowed(&self.name),
337            &Some(ref prefix) => Cow::Owned(format!("{}:{}", prefix, self.name)),
338        };
339        write!(writer, "<{}", name)?;
340
341        for (prefix, ns) in self.namespaces.declared_ns() {
342            match prefix {
343                &None => {
344                    write!(writer, " xmlns=\"")?;
345                    write_escaped(writer, ns)?;
346                    write!(writer, "\"")?;
347                },
348                &Some(ref prefix) => {
349                    write!(writer, " xmlns:{}=\"", prefix)?;
350                    write_escaped(writer, ns)?;
351                    write!(writer, "\"")?;
352                },
353            }
354        }
355
356        for (key, value) in &self.attributes {
357            write!(writer, " {}=\"", key)?;
358                write_escaped(writer, value)?;
359                write!(writer, "\"")?;
360        }
361
362        if self.children.is_empty() {
363            write!(writer, " />")?;
364            return Ok(())
365        }
366
367        write!(writer, ">")?;
368
369        for child in &self.children {
370            child.write_to_inner(writer)?;
371        }
372
373        write!(writer, "</{}>", name)?;
374        Ok(())
375    }
376
377    /// Returns an iterator over references to every child node of this element.
378    ///
379    /// # Examples
380    ///
381    /// ```rust
382    /// use minidom::Element;
383    ///
384    /// let elem: Element = "<root>a<c1 />b<c2 />c</root>".parse().unwrap();
385    ///
386    /// let mut iter = elem.nodes();
387    ///
388    /// assert_eq!(iter.next().unwrap().as_text().unwrap(), "a");
389    /// assert_eq!(iter.next().unwrap().as_element().unwrap().name(), "c1");
390    /// assert_eq!(iter.next().unwrap().as_text().unwrap(), "b");
391    /// assert_eq!(iter.next().unwrap().as_element().unwrap().name(), "c2");
392    /// assert_eq!(iter.next().unwrap().as_text().unwrap(), "c");
393    /// assert_eq!(iter.next(), None);
394    /// ```
395    #[inline] pub fn nodes(&self) -> Nodes {
396        self.children.iter()
397    }
398
399    /// Returns an iterator over mutable references to every child node of this element.
400    #[inline] pub fn nodes_mut(&mut self) -> NodesMut {
401        self.children.iter_mut()
402    }
403
404    /// Returns an iterator over references to every child element of this element.
405    ///
406    /// # Examples
407    ///
408    /// ```rust
409    /// use minidom::Element;
410    ///
411    /// let elem: Element = "<root>hello<child1 />this<child2 />is<child3 />ignored</root>".parse().unwrap();
412    ///
413    /// let mut iter = elem.children();
414    /// assert_eq!(iter.next().unwrap().name(), "child1");
415    /// assert_eq!(iter.next().unwrap().name(), "child2");
416    /// assert_eq!(iter.next().unwrap().name(), "child3");
417    /// assert_eq!(iter.next(), None);
418    /// ```
419    #[inline] pub fn children(&self) -> Children {
420        Children {
421            iter: self.children.iter(),
422        }
423    }
424
425    /// Returns an iterator over mutable references to every child element of this element.
426    #[inline] pub fn children_mut(&mut self) -> ChildrenMut {
427        ChildrenMut {
428            iter: self.children.iter_mut(),
429        }
430    }
431
432    /// Returns an iterator over references to every text node of this element.
433    ///
434    /// # Examples
435    ///
436    /// ```rust
437    /// use minidom::Element;
438    ///
439    /// let elem: Element = "<root>hello<c /> world!</root>".parse().unwrap();
440    ///
441    /// let mut iter = elem.texts();
442    /// assert_eq!(iter.next().unwrap(), "hello");
443    /// assert_eq!(iter.next().unwrap(), " world!");
444    /// assert_eq!(iter.next(), None);
445    /// ```
446    #[inline] pub fn texts(&self) -> Texts {
447        Texts {
448            iter: self.children.iter(),
449        }
450    }
451
452    /// Returns an iterator over mutable references to every text node of this element.
453    #[inline] pub fn texts_mut(&mut self) -> TextsMut {
454        TextsMut {
455            iter: self.children.iter_mut(),
456        }
457    }
458
459    /// Appends a child node to the `Element`, returning the appended node.
460    ///
461    /// # Examples
462    ///
463    /// ```rust
464    /// use minidom::Element;
465    ///
466    /// let mut elem = Element::bare("root");
467    ///
468    /// assert_eq!(elem.children().count(), 0);
469    ///
470    /// elem.append_child(Element::bare("child"));
471    ///
472    /// {
473    ///     let mut iter = elem.children();
474    ///     assert_eq!(iter.next().unwrap().name(), "child");
475    ///     assert_eq!(iter.next(), None);
476    /// }
477    ///
478    /// let child = elem.append_child(Element::bare("new"));
479    ///
480    /// assert_eq!(child.name(), "new");
481    /// ```
482    pub fn append_child(&mut self, child: Element) -> &mut Element {
483        child.namespaces.set_parent(self.namespaces.clone());
484
485        self.children.push(Node::Element(child));
486        if let Node::Element(ref mut cld) = *self.children.last_mut().unwrap() {
487            cld
488        } else {
489            unreachable!()
490        }
491    }
492
493    /// Appends a text node to an `Element`.
494    ///
495    /// # Examples
496    ///
497    /// ```rust
498    /// use minidom::Element;
499    ///
500    /// let mut elem = Element::bare("node");
501    ///
502    /// assert_eq!(elem.text(), "");
503    ///
504    /// elem.append_text_node("text");
505    ///
506    /// assert_eq!(elem.text(), "text");
507    /// ```
508    pub fn append_text_node<S: Into<String>>(&mut self, child: S) {
509        self.children.push(Node::Text(child.into()));
510    }
511
512    /// Appends a node to an `Element`.
513    ///
514    /// # Examples
515    ///
516    /// ```rust
517    /// use minidom::{Element, Node};
518    ///
519    /// let mut elem = Element::bare("node");
520    ///
521    /// elem.append_node(Node::Text("hello".to_owned()));
522    ///
523    /// assert_eq!(elem.text(), "hello");
524    /// ```
525    pub fn append_node(&mut self, node: Node) {
526        self.children.push(node);
527    }
528
529    /// Returns the concatenation of all text nodes in the `Element`.
530    ///
531    /// # Examples
532    ///
533    /// ```rust
534    /// use minidom::Element;
535    ///
536    /// let elem: Element = "<node>hello,<split /> world!</node>".parse().unwrap();
537    ///
538    /// assert_eq!(elem.text(), "hello, world!");
539    /// ```
540    pub fn text(&self) -> String {
541        self.texts().fold(String::new(), |ret, new| ret + new)
542    }
543
544    /// Returns a reference to the first child element with the specific name and namespace, if it
545    /// exists in the direct descendants of this `Element`, else returns `None`.
546    ///
547    /// # Examples
548    ///
549    /// ```rust
550    /// use minidom::Element;
551    ///
552    /// let elem: Element = r#"<node xmlns="ns"><a /><a xmlns="other_ns" /><b /></node>"#.parse().unwrap();
553    ///
554    /// assert!(elem.get_child("a", "ns").unwrap().is("a", "ns"));
555    /// assert!(elem.get_child("a", "other_ns").unwrap().is("a", "other_ns"));
556    /// assert!(elem.get_child("b", "ns").unwrap().is("b", "ns"));
557    /// assert_eq!(elem.get_child("c", "ns"), None);
558    /// assert_eq!(elem.get_child("b", "other_ns"), None);
559    /// assert_eq!(elem.get_child("a", "inexistent_ns"), None);
560    /// ```
561    pub fn get_child<N: AsRef<str>, NS: AsRef<str>>(&self, name: N, namespace: NS) -> Option<&Element> {
562        for fork in &self.children {
563            if let Node::Element(ref e) = *fork {
564                if e.is(name.as_ref(), namespace.as_ref()) {
565                    return Some(e);
566                }
567            }
568        }
569        None
570    }
571
572    /// Returns a mutable reference to the first child element with the specific name and namespace,
573    /// if it exists in the direct descendants of this `Element`, else returns `None`.
574    pub fn get_child_mut<N: AsRef<str>, NS: AsRef<str>>(&mut self, name: N, namespace: NS) -> Option<&mut Element> {
575        for fork in &mut self.children {
576            if let Node::Element(ref mut e) = *fork {
577                if e.is(name.as_ref(), namespace.as_ref()) {
578                    return Some(e);
579                }
580            }
581        }
582        None
583    }
584
585    /// Returns whether a specific child with this name and namespace exists in the direct
586    /// descendants of the `Element`.
587    ///
588    /// # Examples
589    ///
590    /// ```rust
591    /// use minidom::Element;
592    ///
593    /// let elem: Element = r#"<node xmlns="ns"><a /><a xmlns="other_ns" /><b /></node>"#.parse().unwrap();
594    ///
595    /// assert_eq!(elem.has_child("a", "other_ns"), true);
596    /// assert_eq!(elem.has_child("a", "ns"), true);
597    /// assert_eq!(elem.has_child("a", "inexistent_ns"), false);
598    /// assert_eq!(elem.has_child("b", "ns"), true);
599    /// assert_eq!(elem.has_child("b", "other_ns"), false);
600    /// assert_eq!(elem.has_child("b", "inexistent_ns"), false);
601    /// ```
602    pub fn has_child<N: AsRef<str>, NS: AsRef<str>>(&self, name: N, namespace: NS) -> bool {
603        self.get_child(name, namespace).is_some()
604    }
605}
606
607fn split_element_name<S: AsRef<str>>(s: S) -> Result<(Option<String>, String)> {
608    let name_parts = s.as_ref().split(':').collect::<Vec<&str>>();
609    match name_parts.len() {
610        2 => Ok((Some(name_parts[0].to_owned()), name_parts[1].to_owned())),
611        1 => Ok((None, name_parts[0].to_owned())),
612        _ => bail!(ErrorKind::InvalidElement),
613    }
614}
615
616fn build_element(event: &BytesStart) -> Result<Element> {
617    let mut namespaces = BTreeMap::new();
618    let attributes = event.attributes()
619        .map(|o| {
620            let o = o?;
621            let key = str::from_utf8(o.key)?.to_owned();
622            let value = str::from_utf8(o.value)?.to_owned();
623            Ok((key, value))
624        })
625        .filter(|o| {
626            match o {
627                &Ok((ref key, ref value)) if key == "xmlns" => {
628                    namespaces.insert(None, value.to_owned());
629                    false
630                },
631                &Ok((ref key, ref value)) if key.starts_with("xmlns:") => {
632                    namespaces.insert(Some(key[6..].to_owned()), value.to_owned());
633                    false
634                },
635                _ => true,
636            }
637        })
638        .collect::<Result<BTreeMap<String, String>>>()?;
639
640    let (prefix, name) = split_element_name(str::from_utf8(event.name())?)?;
641    let element = Element::new(name, prefix, namespaces, attributes, Vec::new());
642    Ok(element)
643}
644
645/// An iterator over references to child elements of an `Element`.
646pub struct Children<'a> {
647    iter: slice::Iter<'a, Node>,
648}
649
650impl<'a> Iterator for Children<'a> {
651    type Item = &'a Element;
652
653    fn next(&mut self) -> Option<&'a Element> {
654        for item in &mut self.iter {
655            if let Node::Element(ref child) = *item {
656                return Some(child);
657            }
658        }
659        None
660    }
661}
662
663/// An iterator over mutable references to child elements of an `Element`.
664pub struct ChildrenMut<'a> {
665    iter: slice::IterMut<'a, Node>,
666}
667
668impl<'a> Iterator for ChildrenMut<'a> {
669    type Item = &'a mut Element;
670
671    fn next(&mut self) -> Option<&'a mut Element> {
672        for item in &mut self.iter {
673            if let Node::Element(ref mut child) = *item {
674                return Some(child);
675            }
676        }
677        None
678    }
679}
680
681/// An iterator over references to child text nodes of an `Element`.
682pub struct Texts<'a> {
683    iter: slice::Iter<'a, Node>,
684}
685
686impl<'a> Iterator for Texts<'a> {
687    type Item = &'a str;
688
689    fn next(&mut self) -> Option<&'a str> {
690        for item in &mut self.iter {
691            if let Node::Text(ref child) = *item {
692                return Some(child);
693            }
694        }
695        None
696    }
697}
698
699/// An iterator over mutable references to child text nodes of an `Element`.
700pub struct TextsMut<'a> {
701    iter: slice::IterMut<'a, Node>,
702}
703
704impl<'a> Iterator for TextsMut<'a> {
705    type Item = &'a mut String;
706
707    fn next(&mut self) -> Option<&'a mut String> {
708        for item in &mut self.iter {
709            if let Node::Text(ref mut child) = *item {
710                return Some(child);
711            }
712        }
713        None
714    }
715}
716
717/// An iterator over references to all child nodes of an `Element`.
718pub type Nodes<'a> = slice::Iter<'a, Node>;
719
720/// An iterator over mutable references to all child nodes of an `Element`.
721pub type NodesMut<'a> = slice::IterMut<'a, Node>;
722
723/// An iterator over the attributes of an `Element`.
724pub struct Attrs<'a> {
725    iter: btree_map::Iter<'a, String, String>,
726}
727
728impl<'a> Iterator for Attrs<'a> {
729    type Item = (&'a str, &'a str);
730
731    fn next(&mut self) -> Option<Self::Item> {
732        self.iter.next().map(|(x, y)| (x.as_ref(), y.as_ref()))
733    }
734}
735
736/// An iterator over the attributes of an `Element`, with the values mutable.
737pub struct AttrsMut<'a> {
738    iter: btree_map::IterMut<'a, String, String>,
739}
740
741impl<'a> Iterator for AttrsMut<'a> {
742    type Item = (&'a str, &'a mut String);
743
744    fn next(&mut self) -> Option<Self::Item> {
745        self.iter.next().map(|(x, y)| (x.as_ref(), y))
746    }
747}
748
749/// A builder for `Element`s.
750pub struct ElementBuilder {
751    root: Element,
752    namespaces: BTreeMap<Option<String>, String>,
753}
754
755impl ElementBuilder {
756    /// Sets the namespace.
757    pub fn ns<S: Into<String>>(mut self, namespace: S) -> ElementBuilder {
758        self.namespaces
759            .insert(self.root.prefix.clone(), namespace.into());
760        self
761    }
762
763    /// Sets an attribute.
764    pub fn attr<S: Into<String>, V: IntoAttributeValue>(mut self, name: S, value: V) -> ElementBuilder {
765        self.root.set_attr(name, value);
766        self
767    }
768
769    /// Appends anything implementing `IntoElements` into the tree.
770    pub fn append<T: IntoElements>(mut self, into: T) -> ElementBuilder {
771        {
772            let mut emitter = ElementEmitter::new(&mut self.root);
773            into.into_elements(&mut emitter);
774        }
775        self
776    }
777
778    /// Builds the `Element`.
779    pub fn build(self) -> Element {
780        let mut element = self.root;
781        // Set namespaces
782        element.namespaces = Rc::new(NamespaceSet::from(self.namespaces));
783        // Propagate namespaces
784        for node in &element.children {
785            if let Node::Element(ref e) = *node {
786                e.namespaces.set_parent(element.namespaces.clone());
787            }
788        }
789
790        element
791    }
792}
793
794#[cfg(test)]
795#[test]
796fn test_element_new() {
797    use std::iter::FromIterator;
798
799    let elem = Element::new( "name".to_owned()
800                           , None
801                           , Some("namespace".to_owned())
802                           , BTreeMap::from_iter(vec![ ("name".to_string(), "value".to_string()) ].into_iter() )
803                           , Vec::new() );
804
805    assert_eq!(elem.name(), "name");
806    assert_eq!(elem.ns(), Some("namespace".to_owned()));
807    assert_eq!(elem.attr("name"), Some("value"));
808    assert_eq!(elem.attr("inexistent"), None);
809}