tor-browser

viewdesc.ts (63650B)

---

import {DOMSerializer, Fragment, Mark, Node, TagParseRule} from "prosemirror-model"
import {TextSelection} from "prosemirror-state"

import {domIndex, isEquivalentPosition, DOMNode} from "./dom"
import * as browser from "./browser"
import {Decoration, DecorationSource, WidgetConstructor, WidgetType, NodeType} from "./decoration"
import {EditorView} from "./index"

declare global {
 interface Node { 
   /// @internal
   pmViewDesc?: ViewDesc 
 }
}

/// A ViewMutationRecord represents a DOM
/// [mutation](https://developer.mozilla.org/en-US/docs/Web/API/MutationObserver)
/// or a selection change happens within the view. When the change is
/// a selection change, the record will have a `type` property of
/// `"selection"` (which doesn't occur for native mutation records).
export type ViewMutationRecord = MutationRecord | { type: "selection", target: DOMNode }

/// By default, document nodes are rendered using the result of the
/// [`toDOM`](#model.NodeSpec.toDOM) method of their spec, and managed
/// entirely by the editor. For some use cases, such as embedded
/// node-specific editing interfaces, you want more control over
/// the behavior of a node's in-editor representation, and need to
/// [define](#view.EditorProps.nodeViews) a custom node view.
///
/// Objects returned as node views must conform to this interface.
export interface NodeView {
 /// The outer DOM node that represents the document node.
 dom: DOMNode

 /// The DOM node that should hold the node's content. Only meaningful
 /// if the node view also defines a `dom` property and if its node
 /// type is not a leaf node type. When this is present, ProseMirror
 /// will take care of rendering the node's children into it. When it
 /// is not present, the node view itself is responsible for rendering
 /// (or deciding not to render) its child nodes.
 contentDOM?: HTMLElement | null

 /// When given, this will be called when the view is updating
 /// itself. It will be given a node, an array of active decorations
 /// around the node (which are automatically drawn, and the node
 /// view may ignore if it isn't interested in them), and a
 /// [decoration source](#view.DecorationSource) that represents any
 /// decorations that apply to the content of the node (which again
 /// may be ignored). It should return true if it was able to update
 /// to that node, and false otherwise. If the node view has a
 /// `contentDOM` property (or no `dom` property), updating its child
 /// nodes will be handled by ProseMirror.
 update?: (node: Node, decorations: readonly Decoration[], innerDecorations: DecorationSource) => boolean

 /// By default, `update` will only be called when a node of the same
 /// node type appears in this view's position. When you set this to
 /// true, it will be called for any node, making it possible to have
 /// a node view that representsmultiple types of nodes. You will
 /// need to check the type of the nodes you get in `update` and
 /// return `false` for types you cannot handle.
 multiType?: boolean

 /// Can be used to override the way the node's selected status (as a
 /// node selection) is displayed.
 selectNode?: () => void

 /// When defining a `selectNode` method, you should also provide a
 /// `deselectNode` method to remove the effect again.
 deselectNode?: () => void

 /// This will be called to handle setting the selection inside the
 /// node. The `anchor` and `head` positions are relative to the start
 /// of the node. By default, a DOM selection will be created between
 /// the DOM positions corresponding to those positions, but if you
 /// override it you can do something else.
 setSelection?: (anchor: number, head: number, root: Document | ShadowRoot) => void

 /// Can be used to prevent the editor view from trying to handle some
 /// or all DOM events that bubble up from the node view. Events for
 /// which this returns true are not handled by the editor.
 stopEvent?: (event: Event) => boolean

 /// Called when a [mutation](#view.ViewMutationRecord) happens within the
 /// view. Return false if the editor should re-read the selection or re-parse
 /// the range around the mutation, true if it can safely be ignored.
 ignoreMutation?: (mutation: ViewMutationRecord) => boolean

 /// Called when the node view is removed from the editor or the whole
 /// editor is destroyed.
 destroy?: () => void
}

/// By default, document marks are rendered using the result of the
/// [`toDOM`](#model.MarkSpec.toDOM) method of their spec, and managed entirely
/// by the editor. For some use cases, you want more control over the behavior
/// of a mark's in-editor representation, and need to
/// [define](#view.EditorProps.markViews) a custom mark view.
///
/// Objects returned as mark views must conform to this interface.
export interface MarkView {
 /// The outer DOM node that represents the document node.
 dom: DOMNode

 /// The DOM node that should hold the mark's content. When this is not
 /// present, the `dom` property is used as the content DOM.
 contentDOM?: HTMLElement | null

 /// Called when a [mutation](#view.ViewMutationRecord) happens within the
 /// view. Return false if the editor should re-read the selection or re-parse
 /// the range around the mutation, true if it can safely be ignored.
 ignoreMutation?: (mutation: ViewMutationRecord) => boolean

 
 /// Called when the mark view is removed from the editor or the whole
 /// editor is destroyed.
 destroy?: () => void
}

// View descriptions are data structures that describe the DOM that is
// used to represent the editor's content. They are used for:
//
// - Incremental redrawing when the document changes
//
// - Figuring out what part of the document a given DOM position
//   corresponds to
//
// - Wiring in custom implementations of the editing interface for a
//   given node
//
// They form a doubly-linked mutable tree, starting at `view.docView`.

const NOT_DIRTY = 0, CHILD_DIRTY = 1, CONTENT_DIRTY = 2, NODE_DIRTY = 3

// Superclass for the various kinds of descriptions. Defines their
// basic structure and shared methods.
export class ViewDesc {
 dirty = NOT_DIRTY
 declare node: Node | null

 constructor(
   public parent: ViewDesc | undefined,
   public children: ViewDesc[],
   public dom: DOMNode,
   // This is the node that holds the child views. It may be null for
   // descs that don't have children.
   public contentDOM: HTMLElement | null
 ) {
   // An expando property on the DOM node provides a link back to its
   // description.
   dom.pmViewDesc = this
 }

 // Used to check whether a given description corresponds to a
 // widget/mark/node.
 matchesWidget(widget: Decoration) { return false }
 matchesMark(mark: Mark) { return false }
 matchesNode(node: Node, outerDeco: readonly Decoration[], innerDeco: DecorationSource) { return false }
 matchesHack(nodeName: string) { return false }

 // When parsing in-editor content (in domchange.js), we allow
 // descriptions to determine the parse rules that should be used to
 // parse them.
 parseRule(): Omit<TagParseRule, "tag"> | null { return null }

 // Used by the editor's event handler to ignore events that come
 // from certain descs.
 stopEvent(event: Event) { return false }

 // The size of the content represented by this desc.
 get size() {
   let size = 0
   for (let i = 0; i < this.children.length; i++) size += this.children[i].size
   return size
 }

 // For block nodes, this represents the space taken up by their
 // start/end tokens.
 get border() { return 0 }

 destroy() {
   this.parent = undefined
   if (this.dom.pmViewDesc == this) this.dom.pmViewDesc = undefined
   for (let i = 0; i < this.children.length; i++)
     this.children[i].destroy()
 }

 posBeforeChild(child: ViewDesc): number {
   for (let i = 0, pos = this.posAtStart;; i++) {
     let cur = this.children[i]
     if (cur == child) return pos
     pos += cur.size
   }
 }

 get posBefore() {
   return this.parent!.posBeforeChild(this)
 }

 get posAtStart() {
   return this.parent ? this.parent.posBeforeChild(this) + this.border : 0
 }

 get posAfter() {
   return this.posBefore + this.size
 }

 get posAtEnd() {
   return this.posAtStart + this.size - 2 * this.border
 }

 localPosFromDOM(dom: DOMNode, offset: number, bias: number): number {
   // If the DOM position is in the content, use the child desc after
   // it to figure out a position.
   if (this.contentDOM && this.contentDOM.contains(dom.nodeType == 1 ? dom : dom.parentNode)) {
     if (bias < 0) {
       let domBefore, desc: ViewDesc | undefined
       if (dom == this.contentDOM) {
         domBefore = dom.childNodes[offset - 1]
       } else {
         while (dom.parentNode != this.contentDOM) dom = dom.parentNode!
         domBefore = dom.previousSibling
       }
       while (domBefore && !((desc = domBefore.pmViewDesc) && desc.parent == this)) domBefore = domBefore.previousSibling
       return domBefore ? this.posBeforeChild(desc!) + desc!.size : this.posAtStart
     } else {
       let domAfter, desc: ViewDesc | undefined
       if (dom == this.contentDOM) {
         domAfter = dom.childNodes[offset]
       } else {
         while (dom.parentNode != this.contentDOM) dom = dom.parentNode!
         domAfter = dom.nextSibling
       }
       while (domAfter && !((desc = domAfter.pmViewDesc) && desc.parent == this)) domAfter = domAfter.nextSibling
       return domAfter ? this.posBeforeChild(desc!) : this.posAtEnd
     }
   }
   // Otherwise, use various heuristics, falling back on the bias
   // parameter, to determine whether to return the position at the
   // start or at the end of this view desc.
   let atEnd
   if (dom == this.dom && this.contentDOM) {
     atEnd = offset > domIndex(this.contentDOM)
   } else if (this.contentDOM && this.contentDOM != this.dom && this.dom.contains(this.contentDOM)) {
     atEnd = dom.compareDocumentPosition(this.contentDOM) & 2
   } else if (this.dom.firstChild) {
     if (offset == 0) for (let search = dom;; search = search.parentNode!) {
       if (search == this.dom) { atEnd = false; break }
       if (search.previousSibling) break
     }
     if (atEnd == null && offset == dom.childNodes.length) for (let search = dom;; search = search.parentNode!) {
       if (search == this.dom) { atEnd = true; break }
       if (search.nextSibling) break
     }
   }
   return (atEnd == null ? bias > 0 : atEnd) ? this.posAtEnd : this.posAtStart
 }

 // Scan up the dom finding the first desc that is a descendant of
 // this one.
 nearestDesc(dom: DOMNode): ViewDesc | undefined
 nearestDesc(dom: DOMNode, onlyNodes: true): NodeViewDesc | undefined
 nearestDesc(dom: DOMNode, onlyNodes: boolean = false) {
   for (let first = true, cur: DOMNode | null = dom; cur; cur = cur.parentNode) {
     let desc = this.getDesc(cur), nodeDOM
     if (desc && (!onlyNodes || desc.node)) {
       // If dom is outside of this desc's nodeDOM, don't count it.
       if (first && (nodeDOM = (desc as NodeViewDesc).nodeDOM) &&
           !(nodeDOM.nodeType == 1 ? nodeDOM.contains(dom.nodeType == 1 ? dom : dom.parentNode) : nodeDOM == dom))
         first = false
       else
         return desc
     }
   }
 }

 getDesc(dom: DOMNode) {
   let desc = dom.pmViewDesc
   for (let cur: ViewDesc | undefined = desc; cur; cur = cur.parent) if (cur == this) return desc
 }

 posFromDOM(dom: DOMNode, offset: number, bias: number) {
   for (let scan: DOMNode | null = dom; scan; scan = scan.parentNode) {
     let desc = this.getDesc(scan)
     if (desc) return desc.localPosFromDOM(dom, offset, bias)
   }
   return -1
 }

 // Find the desc for the node after the given pos, if any. (When a
 // parent node overrode rendering, there might not be one.)
 descAt(pos: number): ViewDesc | undefined {
   for (let i = 0, offset = 0; i < this.children.length; i++) {
     let child = this.children[i], end = offset + child.size
     if (offset == pos && end != offset) {
       while (!child.border && child.children.length) {
         for (let i = 0; i < child.children.length; i++) {
           let inner = child.children[i]
           if (inner.size) { child = inner; break }
         }
       }
       return child
     }
     if (pos < end) return child.descAt(pos - offset - child.border)
     offset = end
   }
 }

 domFromPos(pos: number, side: number): {node: DOMNode, offset: number, atom?: number} {
   if (!this.contentDOM) return {node: this.dom, offset: 0, atom: pos + 1}
   // First find the position in the child array
   let i = 0, offset = 0
   for (let curPos = 0; i < this.children.length; i++) {
     let child = this.children[i], end = curPos + child.size
     if (end > pos || child instanceof TrailingHackViewDesc) { offset = pos - curPos; break }
     curPos = end
   }
   // If this points into the middle of a child, call through
   if (offset) return this.children[i].domFromPos(offset - this.children[i].border, side)
   // Go back if there were any zero-length widgets with side >= 0 before this point
   for (let prev; i && !(prev = this.children[i - 1]).size && prev instanceof WidgetViewDesc && prev.side >= 0; i--) {}
   // Scan towards the first useable node
   if (side <= 0) {
     let prev, enter = true
     for (;; i--, enter = false) {
       prev = i ? this.children[i - 1] : null
       if (!prev || prev.dom.parentNode == this.contentDOM) break
     }
     if (prev && side && enter && !prev.border && !prev.domAtom) return prev.domFromPos(prev.size, side)
     return {node: this.contentDOM, offset: prev ? domIndex(prev.dom) + 1 : 0}
   } else {
     let next, enter = true
     for (;; i++, enter = false) {
       next = i < this.children.length ? this.children[i] : null
       if (!next || next.dom.parentNode == this.contentDOM) break
     }
     if (next && enter && !next.border && !next.domAtom) return next.domFromPos(0, side)
     return {node: this.contentDOM, offset: next ? domIndex(next.dom) : this.contentDOM.childNodes.length}
   }
 }

 // Used to find a DOM range in a single parent for a given changed
 // range.
 parseRange(
   from: number, to: number, base = 0
 ): {node: DOMNode, from: number, to: number, fromOffset: number, toOffset: number} {
   if (this.children.length == 0)
     return {node: this.contentDOM!, from, to, fromOffset: 0, toOffset: this.contentDOM!.childNodes.length}

   let fromOffset = -1, toOffset = -1
   for (let offset = base, i = 0;; i++) {
     let child = this.children[i], end = offset + child.size
     if (fromOffset == -1 && from <= end) {
       let childBase = offset + child.border
       // FIXME maybe descend mark views to parse a narrower range?
       if (from >= childBase && to <= end - child.border && child.node &&
           child.contentDOM && this.contentDOM!.contains(child.contentDOM))
         return child.parseRange(from, to, childBase)

       from = offset
       for (let j = i; j > 0; j--) {
         let prev = this.children[j - 1]
         if (prev.size && prev.dom.parentNode == this.contentDOM && !prev.emptyChildAt(1)) {
           fromOffset = domIndex(prev.dom) + 1
           break
         }
         from -= prev.size
       }
       if (fromOffset == -1) fromOffset = 0
     }
     if (fromOffset > -1 && (end > to || i == this.children.length - 1)) {
       to = end
       for (let j = i + 1; j < this.children.length; j++) {
         let next = this.children[j]
         if (next.size && next.dom.parentNode == this.contentDOM && !next.emptyChildAt(-1)) {
           toOffset = domIndex(next.dom)
           break
         }
         to += next.size
       }
       if (toOffset == -1) toOffset = this.contentDOM!.childNodes.length
       break
     }
     offset = end
   }
   return {node: this.contentDOM!, from, to, fromOffset, toOffset}
 }

 emptyChildAt(side: number): boolean {
   if (this.border || !this.contentDOM || !this.children.length) return false
   let child = this.children[side < 0 ? 0 : this.children.length - 1]
   return child.size == 0 || child.emptyChildAt(side)
 }

 domAfterPos(pos: number): DOMNode {
   let {node, offset} = this.domFromPos(pos, 0)
   if (node.nodeType != 1 || offset == node.childNodes.length)
     throw new RangeError("No node after pos " + pos)
   return node.childNodes[offset]
 }

 // View descs are responsible for setting any selection that falls
 // entirely inside of them, so that custom implementations can do
 // custom things with the selection. Note that this falls apart when
 // a selection starts in such a node and ends in another, in which
 // case we just use whatever domFromPos produces as a best effort.
 setSelection(anchor: number, head: number, view: EditorView, force = false): void {
   // If the selection falls entirely in a child, give it to that child
   let from = Math.min(anchor, head), to = Math.max(anchor, head)
   for (let i = 0, offset = 0; i < this.children.length; i++) {
     let child = this.children[i], end = offset + child.size
     if (from > offset && to < end)
       return child.setSelection(anchor - offset - child.border, head - offset - child.border, view, force)
     offset = end
   }

   let anchorDOM = this.domFromPos(anchor, anchor ? -1 : 1)
   let headDOM = head == anchor ? anchorDOM : this.domFromPos(head, head ? -1 : 1)
   let domSel = (view.root as Document).getSelection()!
   let selRange = view.domSelectionRange()

   let brKludge = false
   // On Firefox, using Selection.collapse to put the cursor after a
   // BR node for some reason doesn't always work (#1073). On Safari,
   // the cursor sometimes inexplicable visually lags behind its
   // reported position in such situations (#1092).
   if ((browser.gecko || browser.safari) && anchor == head) {
     let {node, offset} = anchorDOM
     if (node.nodeType == 3) {
       brKludge = !!(offset && node.nodeValue![offset - 1] == "\n")
       // Issue #1128
       if (brKludge && offset == node.nodeValue!.length) {
          for (let scan: DOMNode | null = node, after; scan; scan = scan.parentNode) {
           if (after = scan.nextSibling) {
             if (after.nodeName == "BR")
               anchorDOM = headDOM = {node: after.parentNode!, offset: domIndex(after) + 1}
             break
           }
           let desc = scan.pmViewDesc
           if (desc && desc.node && desc.node.isBlock) break
         }
       }
     } else {
       let prev = node.childNodes[offset - 1]
       brKludge = prev && (prev.nodeName == "BR" || (prev as HTMLElement).contentEditable == "false")
     }
   }
   // Firefox can act strangely when the selection is in front of an
   // uneditable node. See #1163 and https://bugzilla.mozilla.org/show_bug.cgi?id=1709536
   if (browser.gecko && selRange.focusNode && selRange.focusNode != headDOM.node && selRange.focusNode.nodeType == 1) {
     let after = selRange.focusNode.childNodes[selRange.focusOffset]
     if (after && (after as HTMLElement).contentEditable == "false") force = true
   }

   if (!(force || brKludge && browser.safari) &&
       isEquivalentPosition(anchorDOM.node, anchorDOM.offset, selRange.anchorNode!, selRange.anchorOffset) &&
       isEquivalentPosition(headDOM.node, headDOM.offset, selRange.focusNode!, selRange.focusOffset))
     return

   // Selection.extend can be used to create an 'inverted' selection
   // (one where the focus is before the anchor), but not all
   // browsers support it yet.
   let domSelExtended = false
   if ((domSel.extend || anchor == head) && !(brKludge && browser.gecko)) {
     domSel.collapse(anchorDOM.node, anchorDOM.offset)
     try {
       if (anchor != head)
         domSel.extend(headDOM.node, headDOM.offset)
       domSelExtended = true
     } catch (_) {
       // In some cases with Chrome the selection is empty after calling
       // collapse, even when it should be valid. This appears to be a bug, but
       // it is difficult to isolate. If this happens fallback to the old path
       // without using extend.
       // Similarly, this could crash on Safari if the editor is hidden, and
       // there was no selection.
     }
   }
   if (!domSelExtended) {
     if (anchor > head) { let tmp = anchorDOM; anchorDOM = headDOM; headDOM = tmp }
     let range = document.createRange()
     range.setEnd(headDOM.node, headDOM.offset)
     range.setStart(anchorDOM.node, anchorDOM.offset)
     domSel.removeAllRanges()
     domSel.addRange(range)
   }
 }

 ignoreMutation(mutation: ViewMutationRecord): boolean {
   return !this.contentDOM && mutation.type != "selection"
 }

 get contentLost() {
   return this.contentDOM && this.contentDOM != this.dom && !this.dom.contains(this.contentDOM)
 }

 // Remove a subtree of the element tree that has been touched
 // by a DOM change, so that the next update will redraw it.
 markDirty(from: number, to: number) {
   for (let offset = 0, i = 0; i < this.children.length; i++) {
     let child = this.children[i], end = offset + child.size
     if (offset == end ? from <= end && to >= offset : from < end && to > offset) {
       let startInside = offset + child.border, endInside = end - child.border
       if (from >= startInside && to <= endInside) {
         this.dirty = from == offset || to == end ? CONTENT_DIRTY : CHILD_DIRTY
         if (from == startInside && to == endInside &&
             (child.contentLost || child.dom.parentNode != this.contentDOM)) child.dirty = NODE_DIRTY
         else child.markDirty(from - startInside, to - startInside)
         return
       } else {
         child.dirty = child.dom == child.contentDOM && child.dom.parentNode == this.contentDOM && !child.children.length
           ? CONTENT_DIRTY : NODE_DIRTY
       }
     }
     offset = end
   }
   this.dirty = CONTENT_DIRTY
 }

 markParentsDirty() {
   let level = 1
   for (let node = this.parent; node; node = node.parent, level++) {
     let dirty = level == 1 ? CONTENT_DIRTY : CHILD_DIRTY
     if (node.dirty < dirty) node.dirty = dirty
   }
 }

 get domAtom() { return false }

 get ignoreForCoords() { return false }

 get ignoreForSelection() { return false }

 isText(text: string) { return false }
}

// A widget desc represents a widget decoration, which is a DOM node
// drawn between the document nodes.
class WidgetViewDesc extends ViewDesc {
 constructor(parent: ViewDesc, readonly widget: Decoration, view: EditorView, pos: number) {
   let self: WidgetViewDesc, dom = (widget.type as any).toDOM as WidgetConstructor
   if (typeof dom == "function") dom = dom(view, () => {
     if (!self) return pos
     if (self.parent) return self.parent.posBeforeChild(self)
   })
   if (!widget.type.spec.raw) {
     if (dom.nodeType != 1) {
       let wrap = document.createElement("span")
       wrap.appendChild(dom)
       dom = wrap
     }
     ;(dom as HTMLElement).contentEditable = "false"
     ;(dom as HTMLElement).classList.add("ProseMirror-widget")
   }
   super(parent, [], dom, null)
   this.widget = widget
   self = this
 }

 matchesWidget(widget: Decoration) {
   return this.dirty == NOT_DIRTY && widget.type.eq(this.widget.type)
 }

 parseRule() { return {ignore: true} }

 stopEvent(event: Event) {
   let stop = this.widget.spec.stopEvent
   return stop ? stop(event) : false
 }

 ignoreMutation(mutation: ViewMutationRecord) {
   return mutation.type != "selection" || this.widget.spec.ignoreSelection
 }

 destroy() {
   this.widget.type.destroy(this.dom)
   super.destroy()
 }

 get domAtom() { return true }

 get ignoreForSelection() { return !!this.widget.type.spec.relaxedSide }

 get side() { return (this.widget.type as any).side as number }
}

class CompositionViewDesc extends ViewDesc {
 constructor(parent: ViewDesc, dom: DOMNode, readonly textDOM: Text, readonly text: string) {
   super(parent, [], dom, null)
 }

 get size() { return this.text.length }

 localPosFromDOM(dom: DOMNode, offset: number) {
   if (dom != this.textDOM) return this.posAtStart + (offset ? this.size : 0)
   return this.posAtStart + offset
 }

 domFromPos(pos: number) {
   return {node: this.textDOM, offset: pos}
 }

 ignoreMutation(mut: ViewMutationRecord) {
   return mut.type === 'characterData' && mut.target.nodeValue == mut.oldValue
  }
}

// A mark desc represents a mark. May have multiple children,
// depending on how the mark is split. Note that marks are drawn using
// a fixed nesting order, for simplicity and predictability, so in
// some cases they will be split more often than would appear
// necessary.
class MarkViewDesc extends ViewDesc {
 constructor(parent: ViewDesc, readonly mark: Mark, dom: DOMNode, contentDOM: HTMLElement, readonly spec: MarkView) {
   super(parent, [], dom, contentDOM)
 }

 static create(parent: ViewDesc, mark: Mark, inline: boolean, view: EditorView) {
   let custom = view.nodeViews[mark.type.name]
   let spec: {dom: HTMLElement, contentDOM?: HTMLElement} = custom && (custom as any)(mark, view, inline)
   if (!spec || !spec.dom)
     spec = (DOMSerializer.renderSpec as any)(document, mark.type.spec.toDOM!(mark, inline), null, mark.attrs) as any
   return new MarkViewDesc(parent, mark, spec.dom, spec.contentDOM || spec.dom as HTMLElement, spec)
 }

 parseRule() {
   if ((this.dirty & NODE_DIRTY) || this.mark.type.spec.reparseInView) return null
   return {mark: this.mark.type.name, attrs: this.mark.attrs, contentElement: this.contentDOM!}
 }

 matchesMark(mark: Mark) { return this.dirty != NODE_DIRTY && this.mark.eq(mark) }

 markDirty(from: number, to: number) {
   super.markDirty(from, to)
   // Move dirty info to nearest node view
   if (this.dirty != NOT_DIRTY) {
     let parent = this.parent!
     while (!parent.node) parent = parent.parent!
     if (parent.dirty < this.dirty) parent.dirty = this.dirty
     this.dirty = NOT_DIRTY
   }
 }

 slice(from: number, to: number, view: EditorView) {
   let copy = MarkViewDesc.create(this.parent!, this.mark, true, view)
   let nodes = this.children, size = this.size
   if (to < size) nodes = replaceNodes(nodes, to, size, view)
   if (from > 0) nodes = replaceNodes(nodes, 0, from, view)
   for (let i = 0; i < nodes.length; i++) nodes[i].parent = copy
   copy.children = nodes
   return copy
 }

 ignoreMutation(mutation: ViewMutationRecord) {
   return this.spec.ignoreMutation ? this.spec.ignoreMutation(mutation) : super.ignoreMutation(mutation)
 }

 destroy() {
   if (this.spec.destroy) this.spec.destroy()
   super.destroy()
 }
}

// Node view descs are the main, most common type of view desc, and
// correspond to an actual node in the document. Unlike mark descs,
// they populate their child array themselves.
export class NodeViewDesc extends ViewDesc {
 constructor(
   parent: ViewDesc | undefined,
   public node: Node,
   public outerDeco: readonly Decoration[],
   public innerDeco: DecorationSource,
   dom: DOMNode,
   contentDOM: HTMLElement | null,
   readonly nodeDOM: DOMNode,
   view: EditorView,
   pos: number
 ) {
   super(parent, [], dom, contentDOM)
 }

 // By default, a node is rendered using the `toDOM` method from the
 // node type spec. But client code can use the `nodeViews` spec to
 // supply a custom node view, which can influence various aspects of
 // the way the node works.
 //
 // (Using subclassing for this was intentionally decided against,
 // since it'd require exposing a whole slew of finicky
 // implementation details to the user code that they probably will
 // never need.)
 static create(parent: ViewDesc | undefined, node: Node, outerDeco: readonly Decoration[],
               innerDeco: DecorationSource, view: EditorView, pos: number) {
   let custom = view.nodeViews[node.type.name], descObj: ViewDesc
   let spec: NodeView | undefined = custom && (custom as any)(node, view, () => {
     // (This is a function that allows the custom view to find its
     // own position)
     if (!descObj) return pos
     if (descObj.parent) return descObj.parent.posBeforeChild(descObj)
   }, outerDeco, innerDeco)

   let dom = spec && spec.dom, contentDOM = spec && spec.contentDOM
   if (node.isText) {
     if (!dom) dom = document.createTextNode(node.text!)
     else if (dom.nodeType != 3) throw new RangeError("Text must be rendered as a DOM text node")
   } else if (!dom) {
     let spec = (DOMSerializer.renderSpec as any)(document, node.type.spec.toDOM!(node), null, node.attrs)
     ;({dom, contentDOM} = spec as {dom: DOMNode, contentDOM?: HTMLElement})
   }
   if (!contentDOM && !node.isText && dom.nodeName != "BR") { // Chrome gets confused by <br contenteditable=false>
     if (!(dom as HTMLElement).hasAttribute("contenteditable")) (dom as HTMLElement).contentEditable = "false"
     if (node.type.spec.draggable) (dom as HTMLElement).draggable = true
   }

   let nodeDOM = dom
   dom = applyOuterDeco(dom, outerDeco, node)

   if (spec)
     return descObj = new CustomNodeViewDesc(parent, node, outerDeco, innerDeco, dom, contentDOM || null, nodeDOM,
                                             spec, view, pos + 1)
   else if (node.isText)
     return new TextViewDesc(parent, node, outerDeco, innerDeco, dom, nodeDOM, view)
   else
     return new NodeViewDesc(parent, node, outerDeco, innerDeco, dom, contentDOM || null, nodeDOM, view, pos + 1)
 }

 parseRule() {
   // Experimental kludge to allow opt-in re-parsing of nodes
   if (this.node.type.spec.reparseInView) return null
   // FIXME the assumption that this can always return the current
   // attrs means that if the user somehow manages to change the
   // attrs in the dom, that won't be picked up. Not entirely sure
   // whether this is a problem
   let rule: Omit<TagParseRule, "tag"> = {node: this.node.type.name, attrs: this.node.attrs}
   if (this.node.type.whitespace == "pre") rule.preserveWhitespace = "full"
   if (!this.contentDOM) {
     rule.getContent = () => this.node.content
   } else if (!this.contentLost) {
     rule.contentElement = this.contentDOM
   } else {
     // Chrome likes to randomly recreate parent nodes when
     // backspacing things. When that happens, this tries to find the
     // new parent.
     for (let i = this.children.length - 1; i >= 0; i--) {
       let child = this.children[i]
       if (this.dom.contains(child.dom.parentNode)) {
         rule.contentElement = child.dom.parentNode as HTMLElement
         break
       }
     }
     if (!rule.contentElement) rule.getContent = () => Fragment.empty
   }
   return rule
 }

 matchesNode(node: Node, outerDeco: readonly Decoration[], innerDeco: DecorationSource) {
   return this.dirty == NOT_DIRTY && node.eq(this.node) &&
     sameOuterDeco(outerDeco, this.outerDeco) && innerDeco.eq(this.innerDeco)
 }

 get size() { return this.node.nodeSize }

 get border() { return this.node.isLeaf ? 0 : 1 }

 // Syncs `this.children` to match `this.node.content` and the local
 // decorations, possibly introducing nesting for marks. Then, in a
 // separate step, syncs the DOM inside `this.contentDOM` to
 // `this.children`.
 updateChildren(view: EditorView, pos: number) {
   let inline = this.node.inlineContent, off = pos
   let composition = view.composing ? this.localCompositionInfo(view, pos) : null
   let localComposition = composition && composition.pos > -1 ? composition : null
   let compositionInChild = composition && composition.pos < 0
   let updater = new ViewTreeUpdater(this, localComposition && localComposition.node, view)
   iterDeco(this.node, this.innerDeco, (widget, i, insideNode) => {
     if (widget.spec.marks)
       updater.syncToMarks(widget.spec.marks, inline, view)
     else if ((widget.type as WidgetType).side >= 0 && !insideNode)
       updater.syncToMarks(i == this.node.childCount ? Mark.none : this.node.child(i).marks, inline, view)
     // If the next node is a desc matching this widget, reuse it,
     // otherwise insert the widget as a new view desc.
     updater.placeWidget(widget, view, off)
   }, (child, outerDeco, innerDeco, i) => {
     // Make sure the wrapping mark descs match the node's marks.
     updater.syncToMarks(child.marks, inline, view)
     // Try several strategies for drawing this node
     let compIndex
     if (updater.findNodeMatch(child, outerDeco, innerDeco, i)) {
       // Found precise match with existing node view
     } else if (compositionInChild && view.state.selection.from > off &&
                view.state.selection.to < off + child.nodeSize &&
                (compIndex = updater.findIndexWithChild(composition!.node)) > -1 &&
                updater.updateNodeAt(child, outerDeco, innerDeco, compIndex, view)) {
       // Updated the specific node that holds the composition
     } else if (updater.updateNextNode(child, outerDeco, innerDeco, view, i, off)) {
       // Could update an existing node to reflect this node
     } else {
       // Add it as a new view
       updater.addNode(child, outerDeco, innerDeco, view, off)
     }
     off += child.nodeSize
   })
   // Drop all remaining descs after the current position.
   updater.syncToMarks([], inline, view)
   if (this.node.isTextblock) updater.addTextblockHacks()
   updater.destroyRest()

   // Sync the DOM if anything changed
   if (updater.changed || this.dirty == CONTENT_DIRTY) {
     // May have to protect focused DOM from being changed if a composition is active
     if (localComposition) this.protectLocalComposition(view, localComposition)
     renderDescs(this.contentDOM!, this.children, view)
     if (browser.ios) iosHacks(this.dom as HTMLElement)
   }
 }

 localCompositionInfo(view: EditorView, pos: number): {node: Text, pos: number, text: string} | null {
   // Only do something if both the selection and a focused text node
   // are inside of this node
   let {from, to} = view.state.selection
   if (!(view.state.selection instanceof TextSelection) || from < pos || to > pos + this.node.content.size) return null
   let textNode = view.input.compositionNode
   if (!textNode || !this.dom.contains(textNode.parentNode)) return null

   if (this.node.inlineContent) {
     // Find the text in the focused node in the node, stop if it's not
     // there (may have been modified through other means, in which
     // case it should overwritten)
     let text = textNode.nodeValue!
     let textPos = findTextInFragment(this.node.content, text, from - pos, to - pos)
     return textPos < 0 ? null : {node: textNode, pos: textPos, text}
   } else {
     return {node: textNode, pos: -1, text: ""}
   }
 }

 protectLocalComposition(view: EditorView, {node, pos, text}: {node: Text, pos: number, text: string}) {
   // The node is already part of a local view desc, leave it there
   if (this.getDesc(node)) return

   // Create a composition view for the orphaned nodes
   let topNode: DOMNode = node
   for (;; topNode = topNode.parentNode!) {
     if (topNode.parentNode == this.contentDOM) break
     while (topNode.previousSibling) topNode.parentNode!.removeChild(topNode.previousSibling)
     while (topNode.nextSibling) topNode.parentNode!.removeChild(topNode.nextSibling)
     if (topNode.pmViewDesc) topNode.pmViewDesc = undefined
   }
   let desc = new CompositionViewDesc(this, topNode, node, text)
   view.input.compositionNodes.push(desc)

   // Patch up this.children to contain the composition view
   this.children = replaceNodes(this.children, pos, pos + text.length, view, desc)
 }

 // If this desc must be updated to match the given node decoration,
 // do so and return true.
 update(node: Node, outerDeco: readonly Decoration[], innerDeco: DecorationSource, view: EditorView) {
   if (this.dirty == NODE_DIRTY ||
       !node.sameMarkup(this.node)) return false
   this.updateInner(node, outerDeco, innerDeco, view)
   return true
 }

 updateInner(node: Node, outerDeco: readonly Decoration[], innerDeco: DecorationSource, view: EditorView) {
   this.updateOuterDeco(outerDeco)
   this.node = node
   this.innerDeco = innerDeco
   if (this.contentDOM) this.updateChildren(view, this.posAtStart)
   this.dirty = NOT_DIRTY
 }

 updateOuterDeco(outerDeco: readonly Decoration[]) {
   if (sameOuterDeco(outerDeco, this.outerDeco)) return
   let needsWrap = this.nodeDOM.nodeType != 1
   let oldDOM = this.dom
   this.dom = patchOuterDeco(this.dom, this.nodeDOM,
                             computeOuterDeco(this.outerDeco, this.node, needsWrap),
                             computeOuterDeco(outerDeco, this.node, needsWrap))
   if (this.dom != oldDOM) {
     oldDOM.pmViewDesc = undefined
     this.dom.pmViewDesc = this
   }
   this.outerDeco = outerDeco
 }

 // Mark this node as being the selected node.
 selectNode() {
   if (this.nodeDOM.nodeType == 1) {
     ;(this.nodeDOM as HTMLElement).classList.add("ProseMirror-selectednode")
     if (this.contentDOM || !this.node.type.spec.draggable) (this.nodeDOM as HTMLElement).draggable = true
   }
 }

 // Remove selected node marking from this node.
 deselectNode() {
   if (this.nodeDOM.nodeType == 1) {
     ;(this.nodeDOM as HTMLElement).classList.remove("ProseMirror-selectednode")
     if (this.contentDOM || !this.node.type.spec.draggable) (this.nodeDOM as HTMLElement).removeAttribute("draggable")
   }
 }

 get domAtom() { return this.node.isAtom }
}

// Create a view desc for the top-level document node, to be exported
// and used by the view class.
export function docViewDesc(doc: Node, outerDeco: readonly Decoration[], innerDeco: DecorationSource,
                           dom: HTMLElement, view: EditorView): NodeViewDesc {
 applyOuterDeco(dom, outerDeco, doc)
 let docView = new NodeViewDesc(undefined, doc, outerDeco, innerDeco, dom, dom, dom, view, 0)
 if (docView.contentDOM) docView.updateChildren(view, 0)
 return docView
}

class TextViewDesc extends NodeViewDesc {
 constructor(parent: ViewDesc | undefined, node: Node, outerDeco: readonly Decoration[],
             innerDeco: DecorationSource, dom: DOMNode, nodeDOM: DOMNode, view: EditorView) {
   super(parent, node, outerDeco, innerDeco, dom, null, nodeDOM, view, 0)
 }

 parseRule() {
   let skip = this.nodeDOM.parentNode
   while (skip && skip != this.dom && !(skip as any).pmIsDeco) skip = skip.parentNode
   return {skip: (skip || true) as any}
 }

 update(node: Node, outerDeco: readonly Decoration[], innerDeco: DecorationSource, view: EditorView) {
   if (this.dirty == NODE_DIRTY || (this.dirty != NOT_DIRTY && !this.inParent()) ||
       !node.sameMarkup(this.node)) return false
   this.updateOuterDeco(outerDeco)
   if ((this.dirty != NOT_DIRTY || node.text != this.node.text) && node.text != this.nodeDOM.nodeValue) {
     this.nodeDOM.nodeValue = node.text!
     if (view.trackWrites == this.nodeDOM) view.trackWrites = null
   }
   this.node = node
   this.dirty = NOT_DIRTY
   return true
 }

 inParent() {
   let parentDOM = this.parent!.contentDOM
   for (let n: DOMNode | null = this.nodeDOM; n; n = n.parentNode) if (n == parentDOM) return true
   return false
 }

 domFromPos(pos: number) {
   return {node: this.nodeDOM, offset: pos}
 }

 localPosFromDOM(dom: DOMNode, offset: number, bias: number) {
   if (dom == this.nodeDOM) return this.posAtStart + Math.min(offset, this.node.text!.length)
   return super.localPosFromDOM(dom, offset, bias)
 }

 ignoreMutation(mutation: ViewMutationRecord) {
   return mutation.type != "characterData" && mutation.type != "selection"
 }

 slice(from: number, to: number, view: EditorView) {
   let node = this.node.cut(from, to), dom = document.createTextNode(node.text!)
   return new TextViewDesc(this.parent, node, this.outerDeco, this.innerDeco, dom, dom, view)
 }

 markDirty(from: number, to: number) {
   super.markDirty(from, to)
   if (this.dom != this.nodeDOM && (from == 0 || to == this.nodeDOM.nodeValue!.length))
     this.dirty = NODE_DIRTY
 }

 get domAtom() { return false }

 isText(text: string) { return this.node.text == text }
}

// A dummy desc used to tag trailing BR or IMG nodes created to work
// around contentEditable terribleness.
class TrailingHackViewDesc extends ViewDesc {
 parseRule() { return {ignore: true} }
 matchesHack(nodeName: string) { return this.dirty == NOT_DIRTY && this.dom.nodeName == nodeName }
 get domAtom() { return true }
 get ignoreForCoords() { return this.dom.nodeName == "IMG" }
}

// A separate subclass is used for customized node views, so that the
// extra checks only have to be made for nodes that are actually
// customized.
class CustomNodeViewDesc extends NodeViewDesc {
 constructor(parent: ViewDesc | undefined, node: Node, outerDeco: readonly Decoration[], innerDeco: DecorationSource,
             dom: DOMNode, contentDOM: HTMLElement | null, nodeDOM: DOMNode, readonly spec: NodeView,
             view: EditorView, pos: number) {
   super(parent, node, outerDeco, innerDeco, dom, contentDOM, nodeDOM, view, pos)
 }

 // A custom `update` method gets to decide whether the update goes
 // through. If it does, and there's a `contentDOM` node, our logic
 // updates the children.
 update(node: Node, outerDeco: readonly Decoration[], innerDeco: DecorationSource, view: EditorView) {
   if (this.dirty == NODE_DIRTY) return false
   if (this.spec.update && (this.node.type == node.type || this.spec.multiType)) {
     let result = this.spec.update(node, outerDeco, innerDeco)
     if (result) this.updateInner(node, outerDeco, innerDeco, view)
     return result
   } else if (!this.contentDOM && !node.isLeaf) {
     return false
   } else {
     return super.update(node, outerDeco, innerDeco, view)
   }
 }

 selectNode() {
   this.spec.selectNode ? this.spec.selectNode() : super.selectNode()
 }

 deselectNode() {
   this.spec.deselectNode ? this.spec.deselectNode() : super.deselectNode()
 }

 setSelection(anchor: number, head: number, view: EditorView, force: boolean) {
   this.spec.setSelection ? this.spec.setSelection(anchor, head, view.root)
     : super.setSelection(anchor, head, view, force)
 }

 destroy() {
   if (this.spec.destroy) this.spec.destroy()
   super.destroy()
 }

 stopEvent(event: Event) {
   return this.spec.stopEvent ? this.spec.stopEvent(event) : false
 }

 ignoreMutation(mutation: ViewMutationRecord) {
   return this.spec.ignoreMutation ? this.spec.ignoreMutation(mutation) : super.ignoreMutation(mutation)
 }
}

// Sync the content of the given DOM node with the nodes associated
// with the given array of view descs, recursing into mark descs
// because this should sync the subtree for a whole node at a time.
function renderDescs(parentDOM: HTMLElement, descs: readonly ViewDesc[], view: EditorView) {
 let dom = parentDOM.firstChild, written = false
 for (let i = 0; i < descs.length; i++) {
   let desc = descs[i], childDOM = desc.dom
   if (childDOM.parentNode == parentDOM) {
     while (childDOM != dom) { dom = rm(dom!); written = true }
     dom = dom.nextSibling
   } else {
     written = true
     parentDOM.insertBefore(childDOM, dom)
   }
   if (desc instanceof MarkViewDesc) {
     let pos = dom ? dom.previousSibling : parentDOM.lastChild
     renderDescs(desc.contentDOM!, desc.children, view)
     dom = pos ? pos.nextSibling : parentDOM.firstChild
   }
 }
 while (dom) { dom = rm(dom); written = true }
 if (written && view.trackWrites == parentDOM) view.trackWrites = null
}

type OuterDecoLevel = {[attr: string]: string}

const OuterDecoLevel: {new (nodeName?: string): OuterDecoLevel} = function(this: any, nodeName?: string) {
 if (nodeName) this.nodeName = nodeName
} as any
OuterDecoLevel.prototype = Object.create(null)

const noDeco = [new OuterDecoLevel]

function computeOuterDeco(outerDeco: readonly Decoration[], node: Node, needsWrap: boolean) {
 if (outerDeco.length == 0) return noDeco

 let top = needsWrap ? noDeco[0] : new OuterDecoLevel, result = [top]

 for (let i = 0; i < outerDeco.length; i++) {
   let attrs = (outerDeco[i].type as NodeType).attrs
   if (!attrs) continue
   if (attrs.nodeName)
     result.push(top = new OuterDecoLevel(attrs.nodeName))

   for (let name in attrs) {
     let val = attrs[name]
     if (val == null) continue
     if (needsWrap && result.length == 1)
       result.push(top = new OuterDecoLevel(node.isInline ? "span" : "div"))
     if (name == "class") top.class = (top.class ? top.class + " " : "") + val
     else if (name == "style") top.style = (top.style ? top.style + ";" : "") + val
     else if (name != "nodeName") top[name] = val
   }
 }

 return result
}

function patchOuterDeco(outerDOM: DOMNode, nodeDOM: DOMNode,
                       prevComputed: readonly OuterDecoLevel[], curComputed: readonly OuterDecoLevel[]) {
 // Shortcut for trivial case
 if (prevComputed == noDeco && curComputed == noDeco) return nodeDOM

 let curDOM = nodeDOM
 for (let i = 0; i < curComputed.length; i++) {
   let deco = curComputed[i], prev = prevComputed[i]
   if (i) {
     let parent: DOMNode | null
     if (prev && prev.nodeName == deco.nodeName && curDOM != outerDOM &&
         (parent = curDOM.parentNode) && parent.nodeName!.toLowerCase() == deco.nodeName) {
       curDOM = parent
     } else {
       parent = document.createElement(deco.nodeName)
       ;(parent as any).pmIsDeco = true
       parent.appendChild(curDOM)
       prev = noDeco[0]
       curDOM = parent
     }
   }
   patchAttributes(curDOM as HTMLElement, prev || noDeco[0], deco)
 }
 return curDOM
}

function patchAttributes(dom: HTMLElement, prev: {[name: string]: string}, cur: {[name: string]: string}) {
 for (let name in prev)
   if (name != "class" && name != "style" && name != "nodeName" && !(name in cur))
     dom.removeAttribute(name)
 for (let name in cur)
   if (name != "class" && name != "style" && name != "nodeName" && cur[name] != prev[name])
     dom.setAttribute(name, cur[name])
 if (prev.class != cur.class) {
   let prevList = prev.class ? prev.class.split(" ").filter(Boolean) : []
   let curList = cur.class ? cur.class.split(" ").filter(Boolean) : []
   for (let i = 0; i < prevList.length; i++) if (curList.indexOf(prevList[i]) == -1)
     dom.classList.remove(prevList[i])
   for (let i = 0; i < curList.length; i++) if (prevList.indexOf(curList[i]) == -1)
     dom.classList.add(curList[i])
   if (dom.classList.length == 0)
     dom.removeAttribute("class")
 }
 if (prev.style != cur.style) {
   if (prev.style) {
     let prop = /\s*([\w\-\xa1-\uffff]+)\s*:(?:"(?:\\.|[^"])*"|'(?:\\.|[^'])*'|\(.*?\)|[^;])*/g, m
     while (m = prop.exec(prev.style))
       dom.style.removeProperty(m[1])
   }
   if (cur.style)
     dom.style.cssText += cur.style
 }
}

function applyOuterDeco(dom: DOMNode, deco: readonly Decoration[], node: Node) {
 return patchOuterDeco(dom, dom, noDeco, computeOuterDeco(deco, node, dom.nodeType != 1))
}

function sameOuterDeco(a: readonly Decoration[], b: readonly Decoration[]) {
 if (a.length != b.length) return false
 for (let i = 0; i < a.length; i++) if (!a[i].type.eq(b[i].type)) return false
 return true
}

// Remove a DOM node and return its next sibling.
function rm(dom: DOMNode) {
 let next = dom.nextSibling
 dom.parentNode!.removeChild(dom)
 return next
}

// Helper class for incrementally updating a tree of mark descs and
// the widget and node descs inside of them.
class ViewTreeUpdater {
 // Index into `this.top`'s child array, represents the current
 // update position.
 index = 0
 // When entering a mark, the current top and index are pushed
 // onto this.
 stack: (ViewDesc | number)[] = []
 // Tracks whether anything was changed
 changed = false
 preMatch: {index: number, matched: Map<ViewDesc, number>, matches: readonly ViewDesc[]}
 top: ViewDesc

 constructor(top: NodeViewDesc, readonly lock: DOMNode | null, private readonly view: EditorView) {
   this.top = top
   this.preMatch = preMatch(top.node.content, top)
 }

 // Destroy and remove the children between the given indices in
 // `this.top`.
 destroyBetween(start: number, end: number) {
   if (start == end) return
   for (let i = start; i < end; i++) this.top.children[i].destroy()
   this.top.children.splice(start, end - start)
   this.changed = true
 }

 // Destroy all remaining children in `this.top`.
 destroyRest() {
   this.destroyBetween(this.index, this.top.children.length)
 }

 // Sync the current stack of mark descs with the given array of
 // marks, reusing existing mark descs when possible.
 syncToMarks(marks: readonly Mark[], inline: boolean, view: EditorView) {
   let keep = 0, depth = this.stack.length >> 1
   let maxKeep = Math.min(depth, marks.length)
   while (keep < maxKeep &&
          (keep == depth - 1 ? this.top : this.stack[(keep + 1) << 1] as ViewDesc)
            .matchesMark(marks[keep]) && marks[keep].type.spec.spanning !== false)
     keep++

   while (keep < depth) {
     this.destroyRest()
     this.top.dirty = NOT_DIRTY
     this.index = this.stack.pop() as number
     this.top = this.stack.pop() as ViewDesc
     depth--
   }
   while (depth < marks.length) {
     this.stack.push(this.top, this.index + 1)
     let found = -1
     for (let i = this.index; i < Math.min(this.index + 3, this.top.children.length); i++) {
       let next = this.top.children[i]
       if (next.matchesMark(marks[depth]) && !this.isLocked(next.dom)) { found = i; break }
     }
     if (found > -1) {
       if (found > this.index) {
         this.changed = true
         this.destroyBetween(this.index, found)
       }
       this.top = this.top.children[this.index]
     } else {
       let markDesc = MarkViewDesc.create(this.top, marks[depth], inline, view)
       this.top.children.splice(this.index, 0, markDesc)
       this.top = markDesc
       this.changed = true
     }
     this.index = 0
     depth++
   }
 }

 // Try to find a node desc matching the given data. Skip over it and
 // return true when successful.
 findNodeMatch(node: Node, outerDeco: readonly Decoration[], innerDeco: DecorationSource, index: number): boolean {
   let found = -1, targetDesc
   if (index >= this.preMatch.index &&
       (targetDesc = this.preMatch.matches[index - this.preMatch.index]).parent == this.top &&
       targetDesc.matchesNode(node, outerDeco, innerDeco)) {
     found = this.top.children.indexOf(targetDesc, this.index)
   } else {
     for (let i = this.index, e = Math.min(this.top.children.length, i + 5); i < e; i++) {
       let child = this.top.children[i]
       if (child.matchesNode(node, outerDeco, innerDeco) && !this.preMatch.matched.has(child)) {
         found = i
         break
       }
     }
   }
   if (found < 0) return false
   this.destroyBetween(this.index, found)
   this.index++
   return true
 }

 updateNodeAt(node: Node, outerDeco: readonly Decoration[], innerDeco: DecorationSource, index: number, view: EditorView) {
   let child = this.top.children[index] as NodeViewDesc
   if (child.dirty == NODE_DIRTY && child.dom == child.contentDOM) child.dirty = CONTENT_DIRTY
   if (!child.update(node, outerDeco, innerDeco, view)) return false
   this.destroyBetween(this.index, index)
   this.index++
   return true
 }

 findIndexWithChild(domNode: DOMNode) {
   for (;;) {
     let parent = domNode.parentNode
     if (!parent) return -1
     if (parent == this.top.contentDOM) {
       let desc = domNode.pmViewDesc
       if (desc) for (let i = this.index; i < this.top.children.length; i++) {
         if (this.top.children[i] == desc) return i
       }
       return -1
     }
     domNode = parent
   }
 }

 // Try to update the next node, if any, to the given data. Checks
 // pre-matches to avoid overwriting nodes that could still be used.
 updateNextNode(node: Node, outerDeco: readonly Decoration[], innerDeco: DecorationSource,
                view: EditorView, index: number, pos: number): boolean {
   for (let i = this.index; i < this.top.children.length; i++) {
     let next = this.top.children[i]
     if (next instanceof NodeViewDesc) {
       let preMatch = this.preMatch.matched.get(next)
       if (preMatch != null && preMatch != index) return false
       let nextDOM = next.dom, updated

       // Can't update if nextDOM is or contains this.lock, except if
       // it's a text node whose content already matches the new text
       // and whose decorations match the new ones.
       let locked = this.isLocked(nextDOM) &&
           !(node.isText && next.node && next.node.isText && next.nodeDOM.nodeValue == node.text &&
             next.dirty != NODE_DIRTY && sameOuterDeco(outerDeco, next.outerDeco))
       if (!locked && next.update(node, outerDeco, innerDeco, view)) {
         this.destroyBetween(this.index, i)
         if (next.dom != nextDOM) this.changed = true
         this.index++
         return true
       } else if (!locked && (updated = this.recreateWrapper(next, node, outerDeco, innerDeco, view, pos))) {
         this.destroyBetween(this.index, i)
         this.top.children[this.index] = updated
         if (updated.contentDOM) {
           updated.dirty = CONTENT_DIRTY
           updated.updateChildren(view, pos + 1)
           updated.dirty = NOT_DIRTY
         }
         this.changed = true
         this.index++
         return true
       }
       break
     }
   }
   return false
 }

 // When a node with content is replaced by a different node with
 // identical content, move over its children.
 recreateWrapper(next: NodeViewDesc, node: Node, outerDeco: readonly Decoration[], innerDeco: DecorationSource,
                 view: EditorView, pos: number) {
   if (next.dirty || node.isAtom || !next.children.length ||
       !next.node.content.eq(node.content) ||
       !sameOuterDeco(outerDeco, next.outerDeco) || !innerDeco.eq(next.innerDeco)) return null
   let wrapper = NodeViewDesc.create(this.top, node, outerDeco, innerDeco, view, pos)
   if (wrapper.contentDOM) {
     wrapper.children = next.children
     next.children = []
     for (let ch of wrapper.children) ch.parent = wrapper
   }
   next.destroy()
   return wrapper
 }

 // Insert the node as a newly created node desc.
 addNode(node: Node, outerDeco: readonly Decoration[], innerDeco: DecorationSource, view: EditorView, pos: number) {
   let desc = NodeViewDesc.create(this.top, node, outerDeco, innerDeco, view, pos)
   if (desc.contentDOM) desc.updateChildren(view, pos + 1)
   this.top.children.splice(this.index++, 0, desc)
   this.changed = true
 }

 placeWidget(widget: Decoration, view: EditorView, pos: number) {
   let next = this.index < this.top.children.length ? this.top.children[this.index] : null
   if (next && next.matchesWidget(widget) &&
       (widget == (next as WidgetViewDesc).widget || !(next as any).widget.type.toDOM.parentNode)) {
     this.index++
   } else {
     let desc = new WidgetViewDesc(this.top, widget, view, pos)
     this.top.children.splice(this.index++, 0, desc)
     this.changed = true
   }
 }

 // Make sure a textblock looks and behaves correctly in
 // contentEditable.
 addTextblockHacks() {
   let lastChild = this.top.children[this.index - 1], parent = this.top
   while (lastChild instanceof MarkViewDesc) {
     parent = lastChild
     lastChild = parent.children[parent.children.length - 1]
   }

   if (!lastChild || // Empty textblock
       !(lastChild instanceof TextViewDesc) ||
       /\n$/.test(lastChild.node.text!) ||
       (this.view.requiresGeckoHackNode && /\s$/.test(lastChild.node.text!))) {
     // Avoid bugs in Safari's cursor drawing (#1165) and Chrome's mouse selection (#1152)
     if ((browser.safari || browser.chrome) && lastChild && (lastChild.dom as HTMLElement).contentEditable == "false")
       this.addHackNode("IMG", parent)
     this.addHackNode("BR", this.top)
   }
 }

 addHackNode(nodeName: string, parent: ViewDesc) {
   if (parent == this.top && this.index < parent.children.length && parent.children[this.index].matchesHack(nodeName)) {
     this.index++
   } else {
     let dom = document.createElement(nodeName)
     if (nodeName == "IMG") {
       dom.className = "ProseMirror-separator"
       ;(dom as HTMLImageElement).alt = ""
     }
     if (nodeName == "BR") dom.className = "ProseMirror-trailingBreak"
     let hack = new TrailingHackViewDesc(this.top, [], dom, null)
     if (parent != this.top) parent.children.push(hack)
     else parent.children.splice(this.index++, 0, hack)
     this.changed = true
   }
 }

 isLocked(node: DOMNode) {
   return this.lock && (node == this.lock || node.nodeType == 1 && node.contains(this.lock.parentNode))
 }
}

// Iterate from the end of the fragment and array of descs to find
// directly matching ones, in order to avoid overeagerly reusing those
// for other nodes. Returns the fragment index of the first node that
// is part of the sequence of matched nodes at the end of the
// fragment.
function preMatch(
 frag: Fragment, parentDesc: ViewDesc
): {index: number, matched: Map<ViewDesc, number>, matches: readonly ViewDesc[]} {
 let curDesc = parentDesc, descI = curDesc.children.length
 let fI = frag.childCount, matched = new Map, matches = []
 outer: while (fI > 0) {
   let desc
   for (;;) {
     if (descI) {
       let next = curDesc.children[descI - 1]
       if (next instanceof MarkViewDesc) {
         curDesc = next
         descI = next.children.length
       } else {
         desc = next
         descI--
         break
       }
     } else if (curDesc == parentDesc) {
       break outer
     } else {
       // FIXME
       descI = curDesc.parent!.children.indexOf(curDesc)
       curDesc = curDesc.parent!
     }
   }
   let node = desc.node
   if (!node) continue
   if (node != frag.child(fI - 1)) break
   --fI
   matched.set(desc, fI)
   matches.push(desc)
 }
 return {index: fI, matched, matches: matches.reverse()}
}

function compareSide(a: Decoration, b: Decoration) {
 return (a.type as WidgetType).side - (b.type as WidgetType).side
}

// This function abstracts iterating over the nodes and decorations in
// a fragment. Calls `onNode` for each node, with its local and child
// decorations. Splits text nodes when there is a decoration starting
// or ending inside of them. Calls `onWidget` for each widget.
function iterDeco(
 parent: Node,
 deco: DecorationSource,
 onWidget: (widget: Decoration, index: number, insideNode: boolean) => void,
 onNode: (node: Node, outerDeco: readonly Decoration[], innerDeco: DecorationSource, index: number) => void
) {
 let locals = deco.locals(parent), offset = 0
 // Simple, cheap variant for when there are no local decorations
 if (locals.length == 0) {
   for (let i = 0; i < parent.childCount; i++) {
     let child = parent.child(i)
     onNode(child, locals, deco.forChild(offset, child), i)
     offset += child.nodeSize
   }
   return
 }

 let decoIndex = 0, active = [], restNode = null
 for (let parentIndex = 0;;) {
   let widget, widgets
   while (decoIndex < locals.length && locals[decoIndex].to == offset) {
     let next = locals[decoIndex++]
     if (next.widget) {
       if (!widget) widget = next
       else (widgets || (widgets = [widget])).push(next)
     }
   }
   if (widget) {
     if (widgets) {
       widgets.sort(compareSide)
       for (let i = 0; i < widgets.length; i++) onWidget(widgets[i], parentIndex, !!restNode)
     } else {
       onWidget(widget, parentIndex, !!restNode)
     }
   }

   let child, index
   if (restNode) {
     index = -1
     child = restNode
     restNode = null
   } else if (parentIndex < parent.childCount) {
     index = parentIndex
     child = parent.child(parentIndex++)
   } else {
     break
   }

   for (let i = 0; i < active.length; i++) if (active[i].to <= offset) active.splice(i--, 1)
   while (decoIndex < locals.length && locals[decoIndex].from <= offset && locals[decoIndex].to > offset)
     active.push(locals[decoIndex++])

   let end = offset + child.nodeSize
   if (child.isText) {
     let cutAt = end
     if (decoIndex < locals.length && locals[decoIndex].from < cutAt) cutAt = locals[decoIndex].from
     for (let i = 0; i < active.length; i++) if (active[i].to < cutAt) cutAt = active[i].to
     if (cutAt < end) {
       restNode = child.cut(cutAt - offset)
       child = child.cut(0, cutAt - offset)
       end = cutAt
       index = -1
     }
   } else {
     while (decoIndex < locals.length && locals[decoIndex].to < end) decoIndex++
   }

   let outerDeco = child.isInline && !child.isLeaf ? active.filter(d => !d.inline) : active.slice()
   onNode(child, outerDeco, deco.forChild(offset, child), index)
   offset = end
 }
}

// List markers in Mobile Safari will mysteriously disappear
// sometimes. This works around that.
function iosHacks(dom: HTMLElement) {
 if (dom.nodeName == "UL" || dom.nodeName == "OL") {
   let oldCSS = dom.style.cssText
   dom.style.cssText = oldCSS + "; list-style: square !important"
   window.getComputedStyle(dom).listStyle
   dom.style.cssText = oldCSS
 }
}

// Find a piece of text in an inline fragment, overlapping from-to
function findTextInFragment(frag: Fragment, text: string, from: number, to: number) {
 for (let i = 0, pos = 0; i < frag.childCount && pos <= to;) {
   let child = frag.child(i++), childStart = pos
   pos += child.nodeSize
   if (!child.isText) continue
   let str = child.text!
   while (i < frag.childCount) {
     let next = frag.child(i++)
     pos += next.nodeSize
     if (!next.isText) break
     str += next.text
   }
   if (pos >= from) {
     if (pos >= to && str.slice(to - text.length - childStart, to - childStart) == text)
       return to - text.length
     let found = childStart < to ? str.lastIndexOf(text, to - childStart - 1) : -1
     if (found >= 0 && found + text.length + childStart >= from)
       return childStart + found
     if (from == to && str.length >= (to + text.length) - childStart &&
         str.slice(to - childStart, to - childStart + text.length) == text)
       return to
   }
 }
 return -1
}

// Replace range from-to in an array of view descs with replacement
// (may be null to just delete). This goes very much against the grain
// of the rest of this code, which tends to create nodes with the
// right shape in one go, rather than messing with them after
// creation, but is necessary in the composition hack.
function replaceNodes(nodes: readonly ViewDesc[], from: number, to: number, view: EditorView, replacement?: ViewDesc) {
 let result = []
 for (let i = 0, off = 0; i < nodes.length; i++) {
   let child = nodes[i], start = off, end = off += child.size
   if (start >= to || end <= from) {
     result.push(child)
   } else {
     if (start < from) result.push((child as MarkViewDesc | TextViewDesc).slice(0, from - start, view))
     if (replacement) {
       result.push(replacement)
       replacement = undefined
     }
     if (end > to) result.push((child as MarkViewDesc | TextViewDesc).slice(to - start, child.size, view))
   }
 }
 return result
}