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use crate::unpretty::remove_insignificant_whitespace;
use crate::xotdata::{Node, Xot};
use crate::access::NodeEdge;
use crate::error::Error;
use crate::name::NameId;
use crate::xmlvalue::{Value, ValueType};
/// ## Manipulation
///
/// These methods maintain a well-formed XML structure:
/// - There is only one document element under the root node which cannot be
/// removed.
/// - The only other nodes that can exist directly under the root node are
/// comments and processing instructions.
/// - You cannot add a node to a node that is not an element or the root node.
///
/// Note that you can use these manipulation methods to move nodes between
/// trees -- if you append a node that's in another tree, that node is first
/// detached from the other tree before it's inserted into the new location.
///
/// If text consolidation is enabled (the default), then also ensures that text
/// nodes are consolidated: two text nodes never appear consecutively. If you
/// add a text node after or before another text node, the text is appended to
/// the existing text node, and the added text node is removed. This also
/// happens if you remove a node causing two text nodes to be adjacent; the
/// second text node is removed.
///
/// You can disable and enable text consolidation using [`Xot::set_text_consolidation`].
///
/// Text node consolidation example:
/// ```rust
/// use xot::Xot;
///
/// let mut xot = Xot::new();
/// let root = xot.parse(r#"<doc>First<s/>Second</doc>"#)?;
///
/// let doc_el = xot.document_element(root).unwrap();
/// let children = xot.children(doc_el).collect::<Vec<_>>();
/// let first = children[0];
/// let s = children[1];
/// let second = children[2];
///
/// // Now we remove s from the document
/// xot.remove(s)?;
///
/// // The text nodes are now adjacent, so the second text node is removed
/// // and merged with the first text node.
///
/// let children = xot.children(doc_el).collect::<Vec<_>>();
/// assert_eq!(children.len(), 1);
/// assert_eq!(xot.text_str(children[0]).unwrap(), "FirstSecond");
///
/// # Ok::<(), xot::Error>(())
/// ```
impl Xot {
/// Append a child to the end of the children of the given parent.
///
/// It is now the new last node of the parent.
///
/// Append returns an error if you place a node in a location that is not
/// allowed, such appending a node to a text node, or appending a new
/// element to the root (there can be only one document element).
///
/// See also the convenience methods [`Xot::append_element`],
/// [`Xot::append_text`], [`Xot::append_comment`] and
/// [`Xot::append_processing_instruction`].
///
/// ```rust
///
/// use xot::Xot;
///
/// let mut xot = Xot::new();
///
/// let root = xot.parse(r#"<doc><p>Example</p></doc>"#)?;
/// let doc_el = xot.document_element(root)?;
///
/// let p_name = xot.add_name("p");
/// let p_el = xot.new_element(p_name);
/// xot.append(doc_el, p_el)?;
///
/// assert_eq!(xot.to_string(root)?, r#"<doc><p>Example</p><p/></doc>"#);
/// # Ok::<(), xot::Error>(())
/// ```
pub fn append(&mut self, parent: Node, child: Node) -> Result<(), Error> {
self.add_structure_check(Some(parent), child)?;
self.remove_consolidate_text_nodes(self.previous_sibling(child), self.next_sibling(child));
if self.add_consolidate_text_nodes(child, self.last_child(parent), None) {
return Ok(());
}
parent.get().checked_append(child.get(), self.arena_mut())?;
Ok(())
}
/// Append a text node to a parent node given text.
///
/// ```rust
///
/// use xot::Xot;
///
/// let mut xot = Xot::new();
/// let root = xot.parse(r#"<doc><p>Example</p></doc>"#)?;
/// let doc_el = xot.document_element(root)?;
///
/// xot.append_text(doc_el, "Hello")?;
///
/// assert_eq!(xot.to_string(root)?, r#"<doc><p>Example</p>Hello</doc>"#);
/// # Ok::<(), xot::Error>(())
/// ```
pub fn append_text(&mut self, parent: Node, text: &str) -> Result<(), Error> {
let text_node_id = self.new_text(text);
self.append(parent, text_node_id)?;
Ok(())
}
/// Append an element node to a parent node given a name.
///
/// Create a name id using [`Xot::add_name`] or [`Xot::add_name_ns`], or
/// reuse an existing name id using [`Xot::name`], [`Xot::name_ns`].
///
/// Example:
/// ```rust
/// use xot::Xot;
///
/// let mut xot = Xot::new();
///
/// let root = xot.parse(r#"<doc></doc>"#)?;
/// let doc_el = xot.document_element(root).unwrap();
///
/// let name_id = xot.add_name("foo");
/// xot.append_element(doc_el, name_id)?;
///
/// assert_eq!(xot.to_string(root)?, "<doc><foo/></doc>");
/// # Ok::<(), xot::Error>(())
/// ```
pub fn append_element(&mut self, parent: Node, name_id: NameId) -> Result<(), Error> {
let element_node_id = self.new_element(name_id);
self.append(parent, element_node_id)?;
Ok(())
}
/// Append a comment node to a parent node given comment text.
pub fn append_comment(&mut self, parent: Node, comment: &str) -> Result<(), Error> {
let comment_node_id = self.new_comment(comment);
self.append(parent, comment_node_id)?;
Ok(())
}
/// Append a processing instruction node to a parent node given target and data.
pub fn append_processing_instruction(
&mut self,
parent: Node,
target: &str,
data: Option<&str>,
) -> Result<(), Error> {
let pi_node_id = self.new_processing_instruction(target, data);
self.append(parent, pi_node_id)?;
Ok(())
}
/// Prepend a child to the beginning of the children of the given parent.
///
/// It is now the new first node of the parent.
pub fn prepend(&mut self, parent: Node, child: Node) -> Result<(), Error> {
self.add_structure_check(Some(parent), child)?;
self.remove_consolidate_text_nodes(self.previous_sibling(child), self.next_sibling(child));
if self.add_consolidate_text_nodes(child, None, self.first_child(parent)) {
return Ok(());
}
parent
.get()
.checked_prepend(child.get(), self.arena_mut())?;
Ok(())
}
/// Insert a new sibling after a reference node.
///
/// ```rust
/// use xot::Xot;
///
/// let mut xot = Xot::new();
/// let root = xot.parse(r#"<doc><a/><c/></doc>"#)?;
///
/// let doc_el = xot.document_element(root)?;
/// let a_el = xot.first_child(doc_el).unwrap();
///
/// let b_name = xot.add_name("b");
/// let b_el = xot.new_element(b_name);
///
/// xot.insert_after(a_el, b_el)?;
///
/// assert_eq!(xot.to_string(root)?, r#"<doc><a/><b/><c/></doc>"#);
/// # Ok::<(), xot::Error>(())
/// ```
pub fn insert_after(&mut self, reference_node: Node, new_sibling: Node) -> Result<(), Error> {
self.add_structure_check(self.parent(reference_node), new_sibling)?;
self.remove_consolidate_text_nodes(
self.previous_sibling(new_sibling),
self.next_sibling(new_sibling),
);
if self.add_consolidate_text_nodes(
new_sibling,
Some(reference_node),
self.next_sibling(reference_node),
) {
return Ok(());
}
reference_node
.get()
.checked_insert_after(new_sibling.get(), self.arena_mut())?;
Ok(())
}
/// Insert a new sibling before a reference node.
pub fn insert_before(&mut self, reference_node: Node, new_sibling: Node) -> Result<(), Error> {
self.add_structure_check(self.parent(reference_node), new_sibling)?;
self.remove_consolidate_text_nodes(
self.previous_sibling(new_sibling),
self.next_sibling(new_sibling),
);
if self.add_consolidate_text_nodes(
new_sibling,
self.previous_sibling(reference_node),
Some(reference_node),
) {
return Ok(());
}
reference_node
.get()
.checked_insert_before(new_sibling.get(), self.arena_mut())?;
Ok(())
}
/// Detach a node (and its descendants) from the tree.
///
/// It now becomes a new xml fragment.
///
/// ```rust
/// use xot::Xot;
///
/// let mut xot = Xot::new();
/// let root = xot.parse(r#"<doc><a><b><c/></b></a></doc>"#)?;
/// let doc_el = xot.document_element(root)?;
/// let a_el = xot.first_child(doc_el).unwrap();
///
/// xot.detach(a_el)?;
///
/// assert_eq!(xot.to_string(root)?, r#"<doc/>"#);
/// assert_eq!(xot.to_string(a_el)?, r#"<a><b><c/></b></a>"#);
///
/// // a_al still exist; it's not removed like with [`Xot::remove`].
/// assert!(!xot.is_removed(a_el));
///
/// # Ok::<(), xot::Error>(())
/// ```
pub fn detach(&mut self, node: Node) -> Result<(), Error> {
self.remove_structure_check(node)?;
let prev_node = self.previous_sibling(node);
let next_node = self.next_sibling(node);
node.get().detach(self.arena_mut());
self.remove_consolidate_text_nodes(prev_node, next_node);
Ok(())
}
/// Remove a node (and its descendants) from the tree
///
/// This removes the nodes from Xot. Trying to access or
/// manipulate a removed node results in a panic. You can verify
/// that a node is removed by using [`Xot::is_removed`].
///
/// ```rust
/// use xot::Xot;
///
/// let mut xot = Xot::new();
/// let root = xot.parse(r#"<doc><a><b><c/></b></a></doc>"#)?;
/// let doc_el = xot.document_element(root)?;
/// let a_el = xot.first_child(doc_el).unwrap();
///
/// xot.remove(a_el)?;
///
/// assert_eq!(xot.to_string(root)?, r#"<doc/>"#);
///
/// // a_al is removed; it's not detached like with [`Xot::detach`].
/// assert!(xot.is_removed(a_el));
///
/// # Ok::<(), xot::Error>(())
/// ```
pub fn remove(&mut self, node: Node) -> Result<(), Error> {
// we don't do a remove structure check, as we should be able to
// remove an entire root if we do it explicitly.
if self.value_type(node) == ValueType::Element && self.is_under_root(node) {
return Err(Error::InvalidOperation("Cannot remove root element".into()));
}
let prev_node = self.previous_sibling(node);
let next_node = self.next_sibling(node);
node.get().remove_subtree(self.arena_mut());
self.remove_consolidate_text_nodes(prev_node, next_node);
Ok(())
}
/// Clone a node and its descendants into a new fragment
///
/// The cloned nodes are not attached to anything. If you clone a root, you
/// clone the whole document.
///
/// This does not include any namespace prefix information defined in any
/// ancestors of the cloned node. If you want to preserve such prefix
/// information, see [`Xot::clone_with_prefixes`].
///
/// ```rust
/// use xot::Xot;
///
/// let mut xot = Xot::new();
/// let root = xot.parse(r#"<doc><a><b><c/></b></a></doc>"#)?;
/// let doc_el = xot.document_element(root)?;
/// let a_el = xot.first_child(doc_el).unwrap();
///
/// let cloned = xot.clone(a_el);
///
/// assert_eq!(xot.to_string(root)?, r#"<doc><a><b><c/></b></a></doc>"#);
///
/// // cloned is not attached to anything
/// assert!(xot.parent(cloned).is_none());
///
/// // cloned is a new fragment
/// assert_eq!(xot.to_string(cloned)?, r#"<a><b><c/></b></a>"#);
///
/// # Ok::<(), xot::Error>(())
/// ```
pub fn clone(&mut self, node: Node) -> Node {
let edges = self.traverse(node).collect::<Vec<_>>();
// we need to create a top node
let top = if self.is_root(node) {
// if we clone a root, we need to create a new root
let value = Value::Root;
self.new_node(value)
} else {
// for anything but the root we create a temporary new element
let top_name = self.add_name("temporary_root");
self.new_element(top_name)
};
let mut current = top;
for open_close in edges {
match open_close {
NodeEdge::Start(node) => {
let value = self.value(node);
let value_type = value.value_type();
if value_type == ValueType::Root {
continue;
}
let new_node = self.new_node(value.clone());
self.append(current, new_node).unwrap();
if value_type == ValueType::Element {
current = new_node;
}
}
NodeEdge::End(node) => {
if self.value_type(node) != ValueType::Element {
continue;
}
current = self.parent(current).unwrap();
}
}
}
if self.is_root(node) {
top
} else {
// remove the temporary element unless we cloned the root
let cloned_node = self.first_child(top).unwrap();
top.get().remove(self.arena_mut());
cloned_node
}
}
/// Clone a node and its descendants into a new fragment
///
/// If the cloned node is an element, required namespace prefixes that are
/// in scope are added to the cloned node. Only those namespaces that
/// are in fact in use in the node or descendants are added.
///
/// ```rust
/// use xot::Xot;
///
/// let mut xot = Xot::new();
/// let root = xot.parse(r#"<doc xmlns:foo="http://example.com"><foo:a><foo:b><foo:c/></foo:b></foo:a></doc>"#)?;
/// let doc_el = xot.document_element(root)?;
/// let a_el = xot.first_child(doc_el).unwrap();
///
/// let cloned = xot.clone_with_prefixes(a_el);
/// assert_eq!(xot.to_string(cloned)?, r#"<foo:a xmlns:foo="http://example.com"><foo:b><foo:c/></foo:b></foo:a>"#);
///
/// // if you do a normal clone, prefixes aren't preserved and need to be generated instead
///
/// let cloned = xot.clone(a_el);
/// xot.create_missing_prefixes(cloned)?;
/// assert_eq!(xot.to_string(cloned)?, r#"<n0:a xmlns:n0="http://example.com"><n0:b><n0:c/></n0:b></n0:a>"#);
///
/// # Ok::<(), xot::Error>(())
/// ```
pub fn clone_with_prefixes(&mut self, node: Node) -> Node {
// get all prefixes defined in scope
let prefixes = self.inherited_prefixes(node);
let clone = self.clone(node);
// add any prefixes from outer scope we may need
if let Some(element) = self.element_mut(clone) {
for (prefix, ns) in prefixes {
if element.prefixes().contains_key(&prefix) {
continue;
}
element.set_prefix(prefix, ns);
}
}
clone
}
/// Unwrap an element; its children are moved to its parent.
///
/// The unwrapped element itself is removed.
///
/// You can unwrap the document element, but only if that document
/// has exactly 1 child that is an element.
///
/// ```rust
/// use xot::Xot;
///
/// let mut xot = Xot::new();
///
/// let root = xot.parse(r#"<doc><a><b><c/></b></a></doc>"#)?;
/// let doc_el = xot.document_element(root)?;
/// let a_el = xot.first_child(doc_el).unwrap();
///
/// xot.element_unwrap(a_el)?;
///
/// assert_eq!(xot.to_string(root)?, r#"<doc><b><c/></b></doc>"#);
///
/// # Ok::<(), xot::Error>(())
/// ```
pub fn element_unwrap(&mut self, node: Node) -> Result<(), Error> {
if !self.is_element(node) {
return Err(Error::InvalidOperation(
"Cannot unwrap non-element nodes".to_string(),
));
}
if self.is_document_element(node) {
// unwrapping is possible if the document element contains exactly one child
// that is an element
if self.children(node).count() != 1 {
return Err(Error::InvalidOperation(
"Can only unwrap document element if it has exactly 1 element child node"
.to_string(),
));
}
// we now know there is 1 child
if !self.is_element(self.first_child(node).unwrap()) {
return Err(Error::InvalidOperation(
"Can only unwrap document element if it has exactly 1 element child node"
.to_string(),
));
}
}
// remove_structure_check is not needed; we already know we don't
// unwrap the root or non-element child, and document element is
// taken care of.
let first_child = self.first_child(node);
// without children this is like a remove
if first_child.is_none() {
return self.remove(node);
}
let first_child = first_child.unwrap();
// there is guaranteed to be a last child if there's a first child
let last_child = self.last_child(node).unwrap();
node.get().remove(self.arena_mut());
let prev_node = self.previous_sibling(first_child);
let next_node = self.next_sibling(last_child);
if self.remove_consolidate_text_nodes(prev_node, Some(first_child)) {
// if first child got consolidated
if first_child == last_child {
// if there was only a single child, try to consolidate prev_node with
// next sibling of last child
self.remove_consolidate_text_nodes(prev_node, next_node);
} else {
// otherwise consolidate last child with next sibling
self.remove_consolidate_text_nodes(Some(last_child), self.next_sibling(last_child));
}
} else {
// first child did not get consolidated
self.remove_consolidate_text_nodes(Some(last_child), self.next_sibling(last_child));
}
Ok(())
}
/// Wrap a node in a new element
///
/// Returns the node for the new wrapping element.
///
/// It's not allowed to wrap the root node. It's allowed to wrap the
/// document element but not any comment or processing instruction nodes
/// directly under the root.
///
/// ```rust
/// use xot::Xot;
///
/// let mut xot = Xot::new();
/// let root = xot.parse(r#"<doc><b><c/></b></doc>"#)?;
/// let doc_el = xot.document_element(root)?;
/// let b_el = xot.first_child(doc_el).unwrap();
///
/// let a_name = xot.add_name("a");
/// let wrapper = xot.element_wrap(b_el, a_name)?;
///
/// assert_eq!(xot.to_string(root)?, r#"<doc><a><b><c/></b></a></doc>"#);
/// assert_eq!(xot.to_string(wrapper)?, r#"<a><b><c/></b></a>"#);
/// # Ok::<(), xot::Error>(())
/// ```
pub fn element_wrap(&mut self, node: Node, name_id: NameId) -> Result<Node, Error> {
if self.is_root(node) {
return Err(Error::InvalidOperation(
"Cannot wrap document root".to_string(),
));
}
// we forbid wrapping nodes under the root too unless it's the
// document element
if self.is_under_root(node) && !self.is_document_element(node) {
return Err(Error::InvalidOperation(
"Cannot wrap nodes under document root except document element".to_string(),
));
}
if let Some(parent) = self.parent(node) {
// record previous sibling
let previous_node = self.previous_sibling(node);
// create new element
let wrapper = self.new_element(name_id);
// detach the node, use low-level detach as we don't want to consolidate
// text nodes
node.get().detach(self.arena_mut());
// append the node to the wrapper
self.append(wrapper, node)?;
// now insert the wrapper element
if let Some(previous_node) = previous_node {
self.insert_after(previous_node, wrapper)?;
} else {
self.prepend(parent, wrapper)?;
}
Ok(wrapper)
} else {
// we have no parent, standalone node
let wrapper = self.new_element(name_id);
self.append(wrapper, node)?;
Ok(wrapper)
}
}
/// Replace a node with another one.
///
/// The replaced node and all its descendants are removed.
///
/// This works for any node, except the document root itself.
///
/// ```rust
/// use xot::Xot;
///
/// let mut xot = Xot::new();
///
/// let root = xot.parse(r#"<doc><a><b/></a><c/></doc>"#)?;
/// let doc_el = xot.document_element(root)?;
/// let a_el = xot.first_child(doc_el).unwrap();
///
/// let d_name = xot.add_name("d");
/// let d_el = xot.new_element(d_name);
///
/// xot.replace(a_el, d_el)?;
///
/// assert_eq!(xot.to_string(root)?, r#"<doc><d/><c/></doc>"#);
/// # Ok::<(), xot::Error>(())
/// ```
pub fn replace(&mut self, replaced_node: Node, replacing_node: Node) -> Result<(), Error> {
if self.is_root(replaced_node) {
return Err(Error::InvalidOperation(
"Cannot replace document root".to_string(),
));
}
// there should always be a parent as we're not root
let parent = self.parent(replaced_node).unwrap();
// record previous sibling
let previous_node = self.previous_sibling(replaced_node);
// remove the replaced node, use low-level remove_tree to avoid
// text node reconciliation and document element detection
replaced_node.get().remove_subtree(self.arena_mut());
// now insert the replacing node
if let Some(previous_node) = previous_node {
self.insert_after(previous_node, replacing_node)?;
} else {
self.prepend(parent, replacing_node)?;
}
Ok(())
}
/// Set text consolidation
///
/// By default, text nodes are consolidated when possible. You can turn
/// off this behavior so text nodes are never merged by calling this.
pub fn set_text_consolidation(&mut self, consolidate: bool) {
self.text_consolidation = consolidate;
}
fn add_structure_check(&self, parent: Option<Node>, child: Node) -> Result<(), Error> {
let parent = parent.ok_or_else(|| {
Error::InvalidOperation("Cannot create siblings for document root".into())
})?;
if !matches!(
self.value_type(parent),
ValueType::Element | ValueType::Root
) {
return Err(Error::InvalidOperation(
"Cannot add children to non-element and non-root node".into(),
));
}
match self.value_type(child) {
ValueType::Root => {
return Err(Error::InvalidOperation("Cannot move document root".into()));
}
ValueType::Element => {
if self.is_under_root(child) {
return Err(Error::InvalidOperation("Cannot move root element".into()));
}
if self.is_root(parent) {
for child in self.children(parent) {
if self.is_element(child) {
return Err(Error::InvalidOperation(
"Cannot move extra element under document root".into(),
));
}
}
}
}
ValueType::Text => {
if self.is_root(parent) {
return Err(Error::InvalidOperation(
"Cannot move text under document root".into(),
));
}
}
ValueType::ProcessingInstruction | ValueType::Comment => {
// these can exist everywhere
}
}
Ok(())
}
fn remove_structure_check(&self, node: Node) -> Result<(), Error> {
match self.value_type(node) {
ValueType::Root => {
return Err(Error::InvalidOperation(
"Cannot remove document root".into(),
));
}
ValueType::Element => {
if self.is_under_root(node) {
return Err(Error::InvalidOperation(
"Cannot remove document element".into(),
));
}
}
ValueType::Text | ValueType::ProcessingInstruction | ValueType::Comment => {
// these have no removal constraints
}
}
Ok(())
}
/// Remove insignificant whitespace
///
/// XML officially does not have a notion of insignificant whitespace, but
/// here we employ the following one: a text node can be removed if
/// it contains only whitespace and has no text sibling that contains
/// non-whitespace text.
pub fn remove_insignificant_whitespace(&mut self, node: Node) {
remove_insignificant_whitespace(self, node);
}
fn add_consolidate_text_nodes(
&mut self,
node: Node,
prev_node: Option<Node>,
next_node: Option<Node>,
) -> bool {
if !self.text_consolidation {
return false;
}
let added_text = if let Value::Text(t) = self.value(node) {
Some(t.get().to_string())
} else {
None
};
if added_text.is_none() {
return false;
}
let added_text = added_text.unwrap();
// if consolidation is turned off, then we could have two adjacent
// text nodes. Prefer to consolidate with the previous node.
let consolidated = if let Some(prev_node) = prev_node {
if let Value::Text(prev) = self.value_mut(prev_node) {
let mut s = prev.get().to_string();
s.push_str(&added_text);
prev.set(s);
// remove the text node we wanted to insert as it's now consolidated
node.get().remove(self.arena_mut());
true
} else {
false
}
} else {
false
};
if consolidated {
return true;
}
// we couldn't consolidate with the previous node, try to consolidate
// with the next node
if let Some(next_node) = next_node {
if let Value::Text(next) = self.value_mut(next_node) {
let mut s = added_text;
s.push_str(next.get());
next.set(s);
// remove the text node we wanted to insert as it's now consolidated
node.get().remove(self.arena_mut());
true
} else {
false
}
} else {
false
}
}
fn remove_consolidate_text_nodes(
&mut self,
prev_node: Option<Node>,
next_node: Option<Node>,
) -> bool {
if !self.text_consolidation {
return false;
}
if prev_node.is_none() {
return false;
}
let prev_node = prev_node.unwrap();
if next_node.is_none() {
return false;
}
let next_node = next_node.unwrap();
let prev_text = self.text(prev_node);
let next_text = self.text(next_node);
if prev_text.is_none() || next_text.is_none() {
return false;
}
let to_add = next_text.unwrap().get().to_string();
let prev_text_mut = self.text_mut(prev_node).unwrap();
let mut s = prev_text_mut.get().to_string();
s.push_str(&to_add);
prev_text_mut.set(s);
next_node.get().remove(self.arena_mut());
true
}
}