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//! Contains XML qualified names manipulation types and functions.
//!
use std::fmt;
use std::str::FromStr;
use namespace::NS_NO_PREFIX;
/// Represents a qualified XML name.
///
/// A qualified name always consists at least of a local name. It can optionally contain
/// a prefix; when reading an XML document, if it contains a prefix, it must also contain a
/// namespace URI, but this is not enforced statically; see below. The name can contain a
/// namespace without a prefix; in that case a default, empty prefix is assumed.
///
/// When writing XML documents, it is possible to omit the namespace URI, leaving only
/// the prefix. In this case the writer will check that the specifed prefix is bound to some
/// URI in the current namespace context. If both prefix and namespace URI are specified,
/// it is checked that the current namespace context contains this exact correspondence
/// between prefix and namespace URI.
///
/// # Prefixes and URIs
///
/// A qualified name with a prefix must always contain a proper namespace URI --- names with
/// a prefix but without a namespace associated with that prefix are meaningless. However,
/// it is impossible to obtain proper namespace URI by a prefix without a context, and such
/// context is only available when parsing a document (or it can be constructed manually
/// when writing a document). Tying a name to a context statically seems impractical. This
/// may change in future, though.
///
/// # Conversions
///
/// `Name` implements some `From` instances for conversion from strings and tuples. For example:
///
/// ```rust
/// # use xml::name::Name;
/// let n1: Name = "p:some-name".into();
/// let n2: Name = ("p", "some-name").into();
///
/// assert_eq!(n1, n2);
/// assert_eq!(n1.local_name, "some-name");
/// assert_eq!(n1.prefix, Some("p"));
/// assert!(n1.namespace.is_none());
/// ```
///
/// This is added to support easy specification of XML elements when writing XML documents.
#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
pub struct Name<'a> {
/// A local name, e.g. `string` in `xsi:string`.
pub local_name: &'a str,
pub namespace: Option<&'a str>,
/// A name prefix, e.g. `xsi` in `xsi:string`.
pub prefix: Option<&'a str>
}
impl<'a> From<&'a str> for Name<'a> {
fn from(s: &'a str) -> Name<'a> {
let mut parts = s.splitn(2, ":").fuse();
match (parts.next(), parts.next()) {
(Some(name), None) => Name::local(name),
(Some(prefix), Some(name)) => Name::prefixed(name, prefix),
_ => unreachable!()
}
}
}
impl<'a> From<(&'a str, &'a str)> for Name<'a> {
fn from((prefix, name): (&'a str, &'a str)) -> Name<'a> {
Name::prefixed(name, prefix)
}
}
impl<'a> fmt::Display for Name<'a> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
if let Some(namespace) = self.namespace {
write!(f, "{{{}}}", namespace)?;
}
if let Some(prefix) = self.prefix {
write!(f, "{}:", prefix)?;
}
write!(f, "{}", self.local_name)
}
}
impl<'a> Name<'a> {
/// Returns an owned variant of the qualified name.
pub fn to_owned(&self) -> OwnedName {
OwnedName {
local_name: self.local_name.into(),
namespace: self.namespace.map(|s| s.into()),
prefix: self.prefix.map(|s| s.into())
}
}
/// Returns a new `Name` instance representing plain local name.
#[inline]
pub fn local(local_name: &str) -> Name {
Name {
local_name,
prefix: None,
namespace: None
}
}
/// Returns a new `Name` instance with the given local name and prefix.
#[inline]
pub fn prefixed(local_name: &'a str, prefix: &'a str) -> Name<'a> {
Name {
local_name,
namespace: None,
prefix: Some(prefix)
}
}
/// Returns a new `Name` instance representing a qualified name with or without a prefix and
/// with a namespace URI.
#[inline]
pub fn qualified(local_name: &'a str, namespace: &'a str, prefix: Option<&'a str>) -> Name<'a> {
Name {
local_name,
namespace: Some(namespace),
prefix,
}
}
/// Returns a correct XML representation of this local name and prefix.
///
/// This method is different from the autoimplemented `to_string()` because it does not
/// include namespace URI in the result.
pub fn to_repr(&self) -> String {
self.repr_display().to_string()
}
/// Returns a structure which can be displayed with `std::fmt` machinery to obtain this
/// local name and prefix.
///
/// This method is needed for efficiency purposes in order not to create unnecessary
/// allocations.
#[inline]
pub fn repr_display(&self) -> ReprDisplay {
ReprDisplay(self)
}
/// Returns either a prefix of this name or `namespace::NS_NO_PREFIX` constant.
#[inline]
pub fn prefix_repr(&self) -> &str {
self.prefix.unwrap_or(NS_NO_PREFIX)
}
}
/// A wrapper around `Name` whose `Display` implementation prints the wrapped name as it is
/// displayed in an XML document.
pub struct ReprDisplay<'a, 'b:'a>(&'a Name<'b>);
impl<'a, 'b:'a> fmt::Display for ReprDisplay<'a, 'b> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match self.0.prefix {
Some(prefix) => write!(f, "{}:{}", prefix, self.0.local_name),
None => write!(f, "{}", self.0.local_name)
}
}
}
/// An owned variant of `Name`.
///
/// Everything about `Name` applies to this structure as well.
#[derive(Clone, PartialEq, Eq, Hash, Debug)]
pub struct OwnedName {
/// A local name, e.g. `string` in `xsi:string`.
pub local_name: String,
pub namespace: Option<String>,
/// A name prefix, e.g. `xsi` in `xsi:string`.
pub prefix: Option<String>,
}
impl fmt::Display for OwnedName {
#[inline]
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
fmt::Display::fmt(&self.borrow(), f)
}
}
impl OwnedName {
/// Constructs a borrowed `Name` based on this owned name.
pub fn borrow(&self) -> Name {
Name {
local_name: &*self.local_name,
namespace: self.namespace.as_ref().map(|s| &**s),
prefix: self.prefix.as_ref().map(|s| &**s),
}
}
/// Returns a new `OwnedName` instance representing a plain local name.
#[inline]
pub fn local<S>(local_name: S) -> OwnedName where S: Into<String> {
OwnedName {
local_name: local_name.into(),
namespace: None,
prefix: None,
}
}
/// Returns a new `OwnedName` instance representing a qualified name with or without
/// a prefix and with a namespace URI.
#[inline]
pub fn qualified<S1, S2, S3>(local_name: S1, namespace: S2, prefix: Option<S3>) -> OwnedName
where S1: Into<String>, S2: Into<String>, S3: Into<String>
{
OwnedName {
local_name: local_name.into(),
namespace: Some(namespace.into()),
prefix: prefix.map(|v| v.into())
}
}
/// Returns an optional prefix by reference, equivalent to `self.borrow().prefix`
/// but avoids extra work.
#[inline]
pub fn prefix_ref(&self) -> Option<&str> {
self.prefix.as_ref().map(|s| &**s)
}
/// Returns an optional namespace by reference, equivalen to `self.borrow().namespace`
/// but avoids extra work.
#[inline]
pub fn namespace_ref(&self) -> Option<&str> {
self.namespace.as_ref().map(|s| &**s)
}
}
impl<'a> From<Name<'a>> for OwnedName {
#[inline]
fn from(n: Name<'a>) -> OwnedName {
n.to_owned()
}
}
impl FromStr for OwnedName {
type Err = ();
/// Parses the given string slice into a qualified name.
///
/// This function, when finishes sucessfully, always return a qualified
/// name without a namespace (`name.namespace == None`). It should be filled later
/// using proper `NamespaceStack`.
///
/// It is supposed that all characters in the argument string are correct
/// as defined by the XML specification. No additional checks except a check
/// for emptiness are done.
fn from_str(s: &str) -> Result<OwnedName, ()> {
let mut it = s.split(':');
let r = match (it.next(), it.next(), it.next()) {
(Some(prefix), Some(local_name), None) if !prefix.is_empty() &&
!local_name.is_empty() =>
Some((local_name.into(), Some(prefix.into()))),
(Some(local_name), None, None) if !local_name.is_empty() =>
Some((local_name.into(), None)),
(_, _, _) => None
};
r.map(|(local_name, prefix)| OwnedName {
local_name,
namespace: None,
prefix
}).ok_or(())
}
}
#[cfg(test)]
mod tests {
use super::OwnedName;
#[test]
fn test_owned_name_from_str() {
assert_eq!("prefix:name".parse(), Ok(OwnedName {
local_name: "name".into(),
namespace: None,
prefix: Some("prefix".into())
}));
assert_eq!("name".parse(), Ok(OwnedName {
local_name: "name".into(),
namespace: None,
prefix: None
}));
assert_eq!("".parse(), Err::<OwnedName, ()>(()));
assert_eq!(":".parse(), Err::<OwnedName, ()>(()));
assert_eq!(":a".parse(), Err::<OwnedName, ()>(()));
assert_eq!("a:".parse(), Err::<OwnedName, ()>(()));
assert_eq!("a:b:c".parse(), Err::<OwnedName, ()>(()));
}
}