1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
//! Contains XML qualified names manipulation types and functions.
//!

use std::fmt;
use std::str::FromStr;

use crate::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,

    /// A namespace URI, e.g. `http://www.w3.org/2000/xmlns/`.
    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}:")?;
        }

        f.write_str(self.local_name)
    }
}

impl<'a> Name<'a> {
    /// Returns an owned variant of the qualified name.
    #[must_use]
    pub fn to_owned(&self) -> OwnedName {
        OwnedName {
            local_name: self.local_name.into(),
            namespace: self.namespace.map(std::convert::Into::into),
            prefix: self.prefix.map(std::convert::Into::into),
        }
    }

    /// Returns a new `Name` instance representing plain local name.
    #[inline]
    #[must_use]
    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]
    #[must_use]
    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]
    #[must_use]
    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.
    #[must_use]
    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]
    #[must_use]
    pub fn repr_display(&self) -> ReprDisplay<'_, '_> {
        ReprDisplay(self)
    }

    /// Returns either a prefix of this name or `namespace::NS_NO_PREFIX` constant.
    #[inline]
    #[must_use]
    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 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 => self.0.local_name.fmt(f),
        }
    }
}

/// 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,

    /// A namespace URI, e.g. `http://www.w3.org/2000/xmlns/`.
    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.
    #[must_use]
    #[inline]
    pub fn borrow(&self) -> Name<'_> {
        Name {
            local_name: &self.local_name,
            namespace: self.namespace.as_deref(),
            prefix: self.prefix.as_deref(),
        }
    }

    /// 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(std::convert::Into::into),
        }
    }

    /// Returns an optional prefix by reference, equivalent to `self.borrow().prefix`
    /// but avoids extra work.
    #[inline]
    #[must_use]
    pub fn prefix_ref(&self) -> Option<&str> {
        self.prefix.as_deref()
    }

    /// Returns an optional namespace by reference, equivalen to `self.borrow().namespace`
    /// but avoids extra work.
    #[inline]
    #[must_use]
    pub fn namespace_ref(&self) -> Option<&str> {
        self.namespace.as_deref()
    }
}

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, ()>(()));
    }
}