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//! Store XML element attributes and their values.
use std::slice;
use std::str;
use markup5ever::{
expanded_name, local_name, namespace_url, ns, LocalName, Namespace, Prefix, QualName,
};
use string_cache::DefaultAtom;
use crate::error::{ImplementationLimit, LoadingError};
use crate::limits;
use crate::util::{opt_utf8_cstr, utf8_cstr, utf8_cstr_bounds};
/// Type used to store attribute values.
///
/// Attribute values are often repeated in an SVG file, so we intern them using the
/// string_cache crate.
pub type AttributeValue = DefaultAtom;
/// Iterable wrapper for libxml2's representation of attribute/value.
/// See the [`new_from_xml2_attributes`] function for information.
/// [`new_from_xml2_attributes`]: #method.new_from_xml2_attributes
#[derive(Clone)]
pub struct Attributes {
attrs: Box<[(QualName, AttributeValue)]>,
id_idx: Option<u16>,
class_idx: Option<u16>,
}
/// Iterator from `Attributes.iter`.
pub struct AttributesIter<'a>(slice::Iter<'a, (QualName, AttributeValue)>);
#[cfg(test)]
impl Default for Attributes {
fn default() -> Self {
Self::new()
impl Attributes {
pub fn new() -> Attributes {
Attributes {
attrs: [].into(),
id_idx: None,
class_idx: None,
/// Creates an iterable `Attributes` from the C array of borrowed C strings.
/// With libxml2's SAX parser, the caller's startElementNsSAX2Func
/// callback gets passed a `xmlChar **` for attributes, which
/// comes in groups of (localname/prefix/URI/value_start/value_end).
/// In those, localname/prefix/URI are NUL-terminated strings;
/// value_start and value_end point to the start-inclusive and
/// end-exclusive bytes in the attribute's value.
/// # Safety
/// This function is unsafe because the caller must guarantee the following:
/// * `attrs` is a valid pointer, with (n_attributes * 5) elements.
/// * All strings are valid UTF-8.
pub unsafe fn new_from_xml2_attributes(
n_attributes: usize,
attrs: *const *const libc::c_char,
) -> Result<Attributes, LoadingError> {
let mut array = Vec::with_capacity(n_attributes);
let mut id_idx = None;
let mut class_idx = None;
if n_attributes > limits::MAX_LOADED_ATTRIBUTES {
return Err(LoadingError::LimitExceeded(
ImplementationLimit::TooManyAttributes,
));
if n_attributes > 0 && !attrs.is_null() {
for attr in slice::from_raw_parts(attrs, n_attributes * 5).chunks_exact(5) {
let localname = attr[0];
let prefix = attr[1];
let uri = attr[2];
let value_start = attr[3];
let value_end = attr[4];
assert!(!localname.is_null());
let localname = utf8_cstr(localname);
let prefix = opt_utf8_cstr(prefix);
let uri = opt_utf8_cstr(uri);
let qual_name = QualName::new(
prefix.map(Prefix::from),
uri.map(Namespace::from)
.unwrap_or_else(|| namespace_url!("")),
LocalName::from(localname),
);
if !value_start.is_null() && !value_end.is_null() {
assert!(value_end >= value_start);
let value_str = utf8_cstr_bounds(value_start, value_end);
let value_atom = DefaultAtom::from(value_str);
let idx = array.len() as u16;
match qual_name.expanded() {
expanded_name!("", "id") => id_idx = Some(idx),
expanded_name!("", "class") => class_idx = Some(idx),
_ => (),
array.push((qual_name, value_atom));
Ok(Attributes {
attrs: array.into(),
id_idx,
class_idx,
})
/// Returns the number of attributes.
pub fn len(&self) -> usize {
self.attrs.len()
/// Creates an iterator that yields `(QualName, &'a str)` tuples.
pub fn iter(&self) -> AttributesIter<'_> {
AttributesIter(self.attrs.iter())
pub fn get_id(&self) -> Option<&str> {
self.id_idx.and_then(|idx| {
self.attrs
.get(usize::from(idx))
.map(|(_name, value)| &value[..])
pub fn get_class(&self) -> Option<&str> {
self.class_idx.and_then(|idx| {
pub fn clear_class(&mut self) {
self.class_idx = None;
impl<'a> Iterator for AttributesIter<'a> {
type Item = (QualName, &'a str);
fn next(&mut self) -> Option<Self::Item> {
self.0.next().map(|(a, v)| (a.clone(), v.as_ref()))
mod tests {
use super::*;
use markup5ever::{expanded_name, local_name, ns};
use std::ffi::CString;
use std::ptr;
#[test]
fn empty_attributes() {
let map = unsafe { Attributes::new_from_xml2_attributes(0, ptr::null()).unwrap() };
assert_eq!(map.len(), 0);
fn attributes_with_namespaces() {
let attrs = [
(
CString::new("href").unwrap(),
Some(CString::new("xlink").unwrap()),
Some(CString::new("http://www.w3.org/1999/xlink").unwrap()),
CString::new("1").unwrap(),
),
CString::new("ry").unwrap(),
None,
CString::new("2").unwrap(),
CString::new("d").unwrap(),
CString::new("").unwrap(),
];
let mut v: Vec<*const libc::c_char> = Vec::new();
for (localname, prefix, uri, val) in &attrs {
v.push(localname.as_ptr());
v.push(
prefix
.as_ref()
.map(|p: &CString| p.as_ptr())
.unwrap_or_else(ptr::null),
uri.as_ref()
let val_start = val.as_ptr();
let val_end = unsafe { val_start.add(val.as_bytes().len()) };
v.push(val_start); // value_start
v.push(val_end); // value_end
let attrs = unsafe { Attributes::new_from_xml2_attributes(3, v.as_ptr()).unwrap() };
let mut had_href: bool = false;
let mut had_ry: bool = false;
let mut had_d: bool = false;
for (a, v) in attrs.iter() {
match a.expanded() {
expanded_name!(xlink "href") => {
assert!(v == "1");
had_href = true;
expanded_name!("", "ry") => {
assert!(v == "2");
had_ry = true;
expanded_name!("", "d") => {
assert!(v.is_empty());
had_d = true;
_ => unreachable!(),
assert!(had_href);
assert!(had_ry);
assert!(had_d);