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Diffstat (limited to 'src/webmentions/check/rcdom.rs')
| -rw-r--r-- | src/webmentions/check/rcdom.rs | 515 |
1 files changed, 515 insertions, 0 deletions
diff --git a/src/webmentions/check/rcdom.rs b/src/webmentions/check/rcdom.rs new file mode 100644 index 0000000..549610f --- /dev/null +++ b/src/webmentions/check/rcdom.rs @@ -0,0 +1,515 @@ +// Copyright 2014-2017 The html5ever Project Developers. +// Copyright Michael Howell and others. +// +// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or +// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +#![allow(missing_docs)] + +//! A simple reference-counted DOM. +//! +//! This is sufficient as a static parse tree, but don't build a +//! web browser using it. :) +//! +//! A DOM is a [tree structure] with ordered children that can be represented in an XML-like +//! format. For example, the following graph +//! +//! ```text +//! div +//! +- "text node" +//! +- span +//! ``` +//! in HTML would be serialized as +//! +//! ```html +//! <div>text node<span></span></div> +//! ``` +//! +//! See the [document object model article on wikipedia][dom wiki] for more information. +//! +//! This implementation stores the information associated with each node once, and then hands out +//! refs to children. The nodes themselves are reference-counted to avoid copying - you can create +//! a new ref and then a node will outlive the document. Nodes own their children, but only have +//! weak references to their parents. +//! +//! [tree structure]: https://en.wikipedia.org/wiki/Tree_(data_structure) +//! [dom wiki]: https://en.wikipedia.org/wiki/Document_Object_Model + +use std::borrow::Cow; +use std::cell::{Cell, RefCell}; +use std::collections::{HashSet, VecDeque}; +use std::default::Default; +use std::fmt; +use std::io; +use std::mem; +use std::rc::{Rc, Weak}; + +use html5ever::tendril::StrTendril; + +use html5ever::interface::tree_builder; +use html5ever::interface::tree_builder::{ElementFlags, NodeOrText, QuirksMode, TreeSink}; +use html5ever::serialize::TraversalScope; +use html5ever::serialize::TraversalScope::{ChildrenOnly, IncludeNode}; +use html5ever::serialize::{Serialize, Serializer}; +use html5ever::Attribute; +use html5ever::ExpandedName; +use html5ever::QualName; + +/// The different kinds of nodes in the DOM. +#[derive(Debug)] +pub enum NodeData { + /// The `Document` itself - the root node of a HTML document. + Document, + + /// A `DOCTYPE` with name, public id, and system id. See + /// [document type declaration on wikipedia][dtd wiki]. + /// + /// [dtd wiki]: https://en.wikipedia.org/wiki/Document_type_declaration + Doctype { + name: StrTendril, + public_id: StrTendril, + system_id: StrTendril, + }, + + /// A text node. + Text { contents: RefCell<StrTendril> }, + + /// A comment. + Comment { contents: StrTendril }, + + /// An element with attributes. + Element { + name: QualName, + attrs: RefCell<Vec<Attribute>>, + + /// For HTML \<template\> elements, the [template contents]. + /// + /// [template contents]: https://html.spec.whatwg.org/multipage/#template-contents + template_contents: RefCell<Option<Handle>>, + + /// Whether the node is a [HTML integration point]. + /// + /// [HTML integration point]: https://html.spec.whatwg.org/multipage/#html-integration-point + mathml_annotation_xml_integration_point: bool, + }, + + /// A Processing instruction. + ProcessingInstruction { + target: StrTendril, + contents: StrTendril, + }, +} + +/// A DOM node. +pub struct Node { + /// Parent node. + pub parent: Cell<Option<WeakHandle>>, + /// Child nodes of this node. + pub children: RefCell<Vec<Handle>>, + /// Represents this node's data. + pub data: NodeData, +} + +impl Node { + /// Create a new node from its contents + pub fn new(data: NodeData) -> Rc<Self> { + Rc::new(Node { + data, + parent: Cell::new(None), + children: RefCell::new(Vec::new()), + }) + } +} + +impl Drop for Node { + fn drop(&mut self) { + let mut nodes = mem::take(&mut *self.children.borrow_mut()); + while let Some(node) = nodes.pop() { + let children = mem::take(&mut *node.children.borrow_mut()); + nodes.extend(children.into_iter()); + if let NodeData::Element { + ref template_contents, + .. + } = node.data + { + if let Some(template_contents) = template_contents.borrow_mut().take() { + nodes.push(template_contents); + } + } + } + } +} + +impl fmt::Debug for Node { + fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result { + fmt.debug_struct("Node") + .field("data", &self.data) + .field("children", &self.children) + .finish() + } +} + +/// Reference to a DOM node. +pub type Handle = Rc<Node>; + +/// Weak reference to a DOM node, used for parent pointers. +pub type WeakHandle = Weak<Node>; + +/// Append a parentless node to another nodes' children +fn append(new_parent: &Handle, child: Handle) { + let previous_parent = child.parent.replace(Some(Rc::downgrade(new_parent))); + // Invariant: child cannot have existing parent + assert!(previous_parent.is_none()); + new_parent.children.borrow_mut().push(child); +} + +/// If the node has a parent, get it and this node's position in its children +fn get_parent_and_index(target: &Handle) -> Option<(Handle, usize)> { + if let Some(weak) = target.parent.take() { + let parent = weak.upgrade().expect("dangling weak pointer"); + target.parent.set(Some(weak)); + let i = match parent + .children + .borrow() + .iter() + .enumerate() + .find(|&(_, child)| Rc::ptr_eq(child, target)) + { + Some((i, _)) => i, + None => panic!("have parent but couldn't find in parent's children!"), + }; + Some((parent, i)) + } else { + None + } +} + +fn append_to_existing_text(prev: &Handle, text: &str) -> bool { + match prev.data { + NodeData::Text { ref contents } => { + contents.borrow_mut().push_slice(text); + true + } + _ => false, + } +} + +fn remove_from_parent(target: &Handle) { + if let Some((parent, i)) = get_parent_and_index(target) { + parent.children.borrow_mut().remove(i); + target.parent.set(None); + } +} + +/// The DOM itself; the result of parsing. +pub struct RcDom { + /// The `Document` itself. + pub document: Handle, + + /// Errors that occurred during parsing. + pub errors: Vec<Cow<'static, str>>, + + /// The document's quirks mode. + pub quirks_mode: QuirksMode, +} + +impl TreeSink for RcDom { + type Output = Self; + fn finish(self) -> Self { + self + } + + type Handle = Handle; + + fn parse_error(&mut self, msg: Cow<'static, str>) { + self.errors.push(msg); + } + + fn get_document(&mut self) -> Handle { + self.document.clone() + } + + fn get_template_contents(&mut self, target: &Handle) -> Handle { + if let NodeData::Element { + ref template_contents, + .. + } = target.data + { + template_contents + .borrow() + .as_ref() + .expect("not a template element!") + .clone() + } else { + panic!("not a template element!") + } + } + + fn set_quirks_mode(&mut self, mode: QuirksMode) { + self.quirks_mode = mode; + } + + fn same_node(&self, x: &Handle, y: &Handle) -> bool { + Rc::ptr_eq(x, y) + } + + fn elem_name<'a>(&self, target: &'a Handle) -> ExpandedName<'a> { + return match target.data { + NodeData::Element { ref name, .. } => name.expanded(), + _ => panic!("not an element!"), + }; + } + + fn create_element( + &mut self, + name: QualName, + attrs: Vec<Attribute>, + flags: ElementFlags, + ) -> Handle { + Node::new(NodeData::Element { + name, + attrs: RefCell::new(attrs), + template_contents: RefCell::new(if flags.template { + Some(Node::new(NodeData::Document)) + } else { + None + }), + mathml_annotation_xml_integration_point: flags.mathml_annotation_xml_integration_point, + }) + } + + fn create_comment(&mut self, text: StrTendril) -> Handle { + Node::new(NodeData::Comment { contents: text }) + } + + fn create_pi(&mut self, target: StrTendril, data: StrTendril) -> Handle { + Node::new(NodeData::ProcessingInstruction { + target, + contents: data, + }) + } + + fn append(&mut self, parent: &Handle, child: NodeOrText<Handle>) { + // Append to an existing Text node if we have one. + if let NodeOrText::AppendText(ref text) = child { + if let Some(h) = parent.children.borrow().last() { + if append_to_existing_text(h, text) { + return; + } + } + } + + append( + parent, + match child { + NodeOrText::AppendText(text) => Node::new(NodeData::Text { + contents: RefCell::new(text), + }), + NodeOrText::AppendNode(node) => node, + }, + ); + } + + fn append_before_sibling(&mut self, sibling: &Handle, child: NodeOrText<Handle>) { + let (parent, i) = get_parent_and_index(sibling) + .expect("append_before_sibling called on node without parent"); + + let child = match (child, i) { + // No previous node. + (NodeOrText::AppendText(text), 0) => Node::new(NodeData::Text { + contents: RefCell::new(text), + }), + + // Look for a text node before the insertion point. + (NodeOrText::AppendText(text), i) => { + let children = parent.children.borrow(); + let prev = &children[i - 1]; + if append_to_existing_text(prev, &text) { + return; + } + Node::new(NodeData::Text { + contents: RefCell::new(text), + }) + } + + // The tree builder promises we won't have a text node after + // the insertion point. + + // Any other kind of node. + (NodeOrText::AppendNode(node), _) => node, + }; + + remove_from_parent(&child); + + child.parent.set(Some(Rc::downgrade(&parent))); + parent.children.borrow_mut().insert(i, child); + } + + fn append_based_on_parent_node( + &mut self, + element: &Self::Handle, + prev_element: &Self::Handle, + child: NodeOrText<Self::Handle>, + ) { + let parent = element.parent.take(); + let has_parent = parent.is_some(); + element.parent.set(parent); + + if has_parent { + self.append_before_sibling(element, child); + } else { + self.append(prev_element, child); + } + } + + fn append_doctype_to_document( + &mut self, + name: StrTendril, + public_id: StrTendril, + system_id: StrTendril, + ) { + append( + &self.document, + Node::new(NodeData::Doctype { + name, + public_id, + system_id, + }), + ); + } + + fn add_attrs_if_missing(&mut self, target: &Handle, attrs: Vec<Attribute>) { + let mut existing = if let NodeData::Element { ref attrs, .. } = target.data { + attrs.borrow_mut() + } else { + panic!("not an element") + }; + + let existing_names = existing + .iter() + .map(|e| e.name.clone()) + .collect::<HashSet<_>>(); + existing.extend( + attrs + .into_iter() + .filter(|attr| !existing_names.contains(&attr.name)), + ); + } + + fn remove_from_parent(&mut self, target: &Handle) { + remove_from_parent(target); + } + + fn reparent_children(&mut self, node: &Handle, new_parent: &Handle) { + let mut children = node.children.borrow_mut(); + let mut new_children = new_parent.children.borrow_mut(); + for child in children.iter() { + let previous_parent = child.parent.replace(Some(Rc::downgrade(new_parent))); + assert!(Rc::ptr_eq( + node, + &previous_parent.unwrap().upgrade().expect("dangling weak") + )) + } + new_children.extend(mem::take(&mut *children)); + } + + fn is_mathml_annotation_xml_integration_point(&self, target: &Handle) -> bool { + if let NodeData::Element { + mathml_annotation_xml_integration_point, + .. + } = target.data + { + mathml_annotation_xml_integration_point + } else { + panic!("not an element!") + } + } +} + +impl Default for RcDom { + fn default() -> RcDom { + RcDom { + document: Node::new(NodeData::Document), + errors: vec![], + quirks_mode: tree_builder::NoQuirks, + } + } +} + +enum SerializeOp { + Open(Handle), + Close(QualName), +} + +pub struct SerializableHandle(Handle); + +impl From<Handle> for SerializableHandle { + fn from(h: Handle) -> SerializableHandle { + SerializableHandle(h) + } +} + +impl Serialize for SerializableHandle { + fn serialize<S>(&self, serializer: &mut S, traversal_scope: TraversalScope) -> io::Result<()> + where + S: Serializer, + { + let mut ops = VecDeque::new(); + match traversal_scope { + IncludeNode => ops.push_back(SerializeOp::Open(self.0.clone())), + ChildrenOnly(_) => ops.extend( + self.0 + .children + .borrow() + .iter() + .map(|h| SerializeOp::Open(h.clone())), + ), + } + + while let Some(op) = ops.pop_front() { + match op { + SerializeOp::Open(handle) => match handle.data { + NodeData::Element { + ref name, + ref attrs, + .. + } => { + serializer.start_elem( + name.clone(), + attrs.borrow().iter().map(|at| (&at.name, &at.value[..])), + )?; + + ops.reserve(1 + handle.children.borrow().len()); + ops.push_front(SerializeOp::Close(name.clone())); + + for child in handle.children.borrow().iter().rev() { + ops.push_front(SerializeOp::Open(child.clone())); + } + } + + NodeData::Doctype { ref name, .. } => serializer.write_doctype(name)?, + + NodeData::Text { ref contents } => serializer.write_text(&contents.borrow())?, + + NodeData::Comment { ref contents } => serializer.write_comment(contents)?, + + NodeData::ProcessingInstruction { + ref target, + ref contents, + } => serializer.write_processing_instruction(target, contents)?, + + NodeData::Document => panic!("Can't serialize Document node itself"), + }, + + SerializeOp::Close(name) => { + serializer.end_elem(name)?; + } + } + } + + Ok(()) + } +} |