tor-browser

replace.ts (20249B)

---

import {Fragment, Slice, Node, ResolvedPos, NodeType, ContentMatch, Attrs} from "prosemirror-model"

import {Step} from "./step"
import {ReplaceStep, ReplaceAroundStep} from "./replace_step"
import {Transform} from "./transform"
import {insertPoint} from "./structure"

/// ‘Fit’ a slice into a given position in the document, producing a
/// [step](#transform.Step) that inserts it. Will return null if
/// there's no meaningful way to insert the slice here, or inserting it
/// would be a no-op (an empty slice over an empty range).
export function replaceStep(doc: Node, from: number, to = from, slice = Slice.empty): Step | null {
 if (from == to && !slice.size) return null

 let $from = doc.resolve(from), $to = doc.resolve(to)
 // Optimization -- avoid work if it's obvious that it's not needed.
 if (fitsTrivially($from, $to, slice)) return new ReplaceStep(from, to, slice)
 return new Fitter($from, $to, slice).fit()
}

function fitsTrivially($from: ResolvedPos, $to: ResolvedPos, slice: Slice) {
 return !slice.openStart && !slice.openEnd && $from.start() == $to.start() &&
   $from.parent.canReplace($from.index(), $to.index(), slice.content)
}

interface Fittable {
 sliceDepth: number
 frontierDepth: number
 parent: Node | null
 inject?: Fragment | null
 wrap?: readonly NodeType[]
}

// Algorithm for 'placing' the elements of a slice into a gap:
//
// We consider the content of each node that is open to the left to be
// independently placeable. I.e. in <p("foo"), p("bar")>, when the
// paragraph on the left is open, "foo" can be placed (somewhere on
// the left side of the replacement gap) independently from p("bar").
//
// This class tracks the state of the placement progress in the
// following properties:
//
//  - `frontier` holds a stack of `{type, match}` objects that
//    represent the open side of the replacement. It starts at
//    `$from`, then moves forward as content is placed, and is finally
//    reconciled with `$to`.
//
//  - `unplaced` is a slice that represents the content that hasn't
//    been placed yet.
//
//  - `placed` is a fragment of placed content. Its open-start value
//    is implicit in `$from`, and its open-end value in `frontier`.
class Fitter {
 frontier: {type: NodeType, match: ContentMatch}[] = []
 placed: Fragment = Fragment.empty

 constructor(
   readonly $from: ResolvedPos,
   readonly $to: ResolvedPos,
   public unplaced: Slice
 ) {
   for (let i = 0; i <= $from.depth; i++) {
     let node = $from.node(i)
     this.frontier.push({
       type: node.type,
       match: node.contentMatchAt($from.indexAfter(i))
     })
   }

   for (let i = $from.depth; i > 0; i--)
     this.placed = Fragment.from($from.node(i).copy(this.placed))
 }

 get depth() { return this.frontier.length - 1 }

 fit() {
   // As long as there's unplaced content, try to place some of it.
   // If that fails, either increase the open score of the unplaced
   // slice, or drop nodes from it, and then try again.
   while (this.unplaced.size) {
     let fit = this.findFittable()
     if (fit) this.placeNodes(fit)
     else this.openMore() || this.dropNode()
   }
   // When there's inline content directly after the frontier _and_
   // directly after `this.$to`, we must generate a `ReplaceAround`
   // step that pulls that content into the node after the frontier.
   // That means the fitting must be done to the end of the textblock
   // node after `this.$to`, not `this.$to` itself.
   let moveInline = this.mustMoveInline(), placedSize = this.placed.size - this.depth - this.$from.depth
   let $from = this.$from, $to = this.close(moveInline < 0 ? this.$to : $from.doc.resolve(moveInline))
   if (!$to) return null

   // If closing to `$to` succeeded, create a step
   let content = this.placed, openStart = $from.depth, openEnd = $to.depth
   while (openStart && openEnd && content.childCount == 1) { // Normalize by dropping open parent nodes
     content = content.firstChild!.content
     openStart--; openEnd--
   }
   let slice = new Slice(content, openStart, openEnd)
   if (moveInline > -1)
     return new ReplaceAroundStep($from.pos, moveInline, this.$to.pos, this.$to.end(), slice, placedSize)
   if (slice.size || $from.pos != this.$to.pos) // Don't generate no-op steps
     return new ReplaceStep($from.pos, $to.pos, slice)
   return null
 }

 // Find a position on the start spine of `this.unplaced` that has
 // content that can be moved somewhere on the frontier. Returns two
 // depths, one for the slice and one for the frontier.
 findFittable(): Fittable | undefined {
   let startDepth = this.unplaced.openStart
   for (let cur = this.unplaced.content, d = 0, openEnd = this.unplaced.openEnd; d < startDepth; d++) {
     let node = cur.firstChild!
     if (cur.childCount > 1) openEnd = 0
     if (node.type.spec.isolating && openEnd <= d) {
       startDepth = d
       break
     }
     cur = node.content
   }

   // Only try wrapping nodes (pass 2) after finding a place without
   // wrapping failed.
   for (let pass = 1; pass <= 2; pass++) {
     for (let sliceDepth = pass == 1 ? startDepth : this.unplaced.openStart; sliceDepth >= 0; sliceDepth--) {
       let fragment, parent = null
       if (sliceDepth) {
         parent = contentAt(this.unplaced.content, sliceDepth - 1).firstChild
         fragment = parent!.content
       } else {
         fragment = this.unplaced.content
       }
       let first = fragment.firstChild
       for (let frontierDepth = this.depth; frontierDepth >= 0; frontierDepth--) {
         let {type, match} = this.frontier[frontierDepth], wrap, inject: Fragment | null = null
         // In pass 1, if the next node matches, or there is no next
         // node but the parents look compatible, we've found a
         // place.
         if (pass == 1 && (first ? match.matchType(first.type) || (inject = match.fillBefore(Fragment.from(first), false))
                           : parent && type.compatibleContent(parent.type)))
           return {sliceDepth, frontierDepth, parent, inject}
         // In pass 2, look for a set of wrapping nodes that make
         // `first` fit here.
         else if (pass == 2 && first && (wrap = match.findWrapping(first.type)))
           return {sliceDepth, frontierDepth, parent, wrap}
         // Don't continue looking further up if the parent node
         // would fit here.
         if (parent && match.matchType(parent.type)) break
       }
     }
   }
 }

 openMore() {
   let {content, openStart, openEnd} = this.unplaced
   let inner = contentAt(content, openStart)
   if (!inner.childCount || inner.firstChild!.isLeaf) return false
   this.unplaced = new Slice(content, openStart + 1,
                             Math.max(openEnd, inner.size + openStart >= content.size - openEnd ? openStart + 1 : 0))
   return true
 }

 dropNode() {
   let {content, openStart, openEnd} = this.unplaced
   let inner = contentAt(content, openStart)
   if (inner.childCount <= 1 && openStart > 0) {
     let openAtEnd = content.size - openStart <= openStart + inner.size
     this.unplaced = new Slice(dropFromFragment(content, openStart - 1, 1), openStart - 1,
                               openAtEnd ? openStart - 1 : openEnd)
   } else {
     this.unplaced = new Slice(dropFromFragment(content, openStart, 1), openStart, openEnd)
   }
 }

 // Move content from the unplaced slice at `sliceDepth` to the
 // frontier node at `frontierDepth`. Close that frontier node when
 // applicable.
 placeNodes({sliceDepth, frontierDepth, parent, inject, wrap}: Fittable) {
   while (this.depth > frontierDepth) this.closeFrontierNode()
   if (wrap) for (let i = 0; i < wrap.length; i++) this.openFrontierNode(wrap[i])

   let slice = this.unplaced, fragment = parent ? parent.content : slice.content
   let openStart = slice.openStart - sliceDepth
   let taken = 0, add = []
   let {match, type} = this.frontier[frontierDepth]
   if (inject) {
     for (let i = 0; i < inject.childCount; i++) add.push(inject.child(i))
     match = match.matchFragment(inject)!
   }
   // Computes the amount of (end) open nodes at the end of the
   // fragment. When 0, the parent is open, but no more. When
   // negative, nothing is open.
   let openEndCount = (fragment.size + sliceDepth) - (slice.content.size - slice.openEnd)
   // Scan over the fragment, fitting as many child nodes as
   // possible.
   while (taken < fragment.childCount) {
     let next = fragment.child(taken), matches = match.matchType(next.type)
     if (!matches) break
     taken++
     if (taken > 1 || openStart == 0 || next.content.size) { // Drop empty open nodes
       match = matches
       add.push(closeNodeStart(next.mark(type.allowedMarks(next.marks)), taken == 1 ? openStart : 0,
                               taken == fragment.childCount ? openEndCount : -1))
     }
   }
   let toEnd = taken == fragment.childCount
   if (!toEnd) openEndCount = -1

   this.placed = addToFragment(this.placed, frontierDepth, Fragment.from(add))
   this.frontier[frontierDepth].match = match

   // If the parent types match, and the entire node was moved, and
   // it's not open, close this frontier node right away.
   if (toEnd && openEndCount < 0 && parent && parent.type == this.frontier[this.depth].type && this.frontier.length > 1)
     this.closeFrontierNode()

   // Add new frontier nodes for any open nodes at the end.
   for (let i = 0, cur = fragment; i < openEndCount; i++) {
     let node = cur.lastChild!
     this.frontier.push({type: node.type, match: node.contentMatchAt(node.childCount)})
     cur = node.content
   }

   // Update `this.unplaced`. Drop the entire node from which we
   // placed it we got to its end, otherwise just drop the placed
   // nodes.
   this.unplaced = !toEnd ? new Slice(dropFromFragment(slice.content, sliceDepth, taken), slice.openStart, slice.openEnd)
     : sliceDepth == 0 ? Slice.empty
     : new Slice(dropFromFragment(slice.content, sliceDepth - 1, 1),
                 sliceDepth - 1, openEndCount < 0 ? slice.openEnd : sliceDepth - 1)
 }

 mustMoveInline() {
   if (!this.$to.parent.isTextblock) return -1
   let top = this.frontier[this.depth], level
   if (!top.type.isTextblock || !contentAfterFits(this.$to, this.$to.depth, top.type, top.match, false) ||
       (this.$to.depth == this.depth && (level = this.findCloseLevel(this.$to)) && level.depth == this.depth)) return -1

   let {depth} = this.$to, after = this.$to.after(depth)
   while (depth > 1 && after == this.$to.end(--depth)) ++after
   return after
 }

 findCloseLevel($to: ResolvedPos) {
   scan: for (let i = Math.min(this.depth, $to.depth); i >= 0; i--) {
     let {match, type} = this.frontier[i]
     let dropInner = i < $to.depth && $to.end(i + 1) == $to.pos + ($to.depth - (i + 1))
     let fit = contentAfterFits($to, i, type, match, dropInner)
     if (!fit) continue
     for (let d = i - 1; d >= 0; d--) {
       let {match, type} = this.frontier[d]
       let matches = contentAfterFits($to, d, type, match, true)
       if (!matches || matches.childCount) continue scan
     }
     return {depth: i, fit, move: dropInner ? $to.doc.resolve($to.after(i + 1)) : $to}
   }
 }

 close($to: ResolvedPos) {
   let close = this.findCloseLevel($to)
   if (!close) return null

   while (this.depth > close.depth) this.closeFrontierNode()
   if (close.fit.childCount) this.placed = addToFragment(this.placed, close.depth, close.fit)
   $to = close.move
   for (let d = close.depth + 1; d <= $to.depth; d++) {
     let node = $to.node(d), add = node.type.contentMatch.fillBefore(node.content, true, $to.index(d))!
     this.openFrontierNode(node.type, node.attrs, add)
   }
   return $to
 }

 openFrontierNode(type: NodeType, attrs: Attrs | null = null, content?: Fragment) {
   let top = this.frontier[this.depth]
   top.match = top.match.matchType(type)!
   this.placed = addToFragment(this.placed, this.depth, Fragment.from(type.create(attrs, content)))
   this.frontier.push({type, match: type.contentMatch})
 }

 closeFrontierNode() {
   let open = this.frontier.pop()!
   let add = open.match.fillBefore(Fragment.empty, true)!
   if (add.childCount) this.placed = addToFragment(this.placed, this.frontier.length, add)
 }
}

function dropFromFragment(fragment: Fragment, depth: number, count: number): Fragment {
 if (depth == 0) return fragment.cutByIndex(count, fragment.childCount)
 return fragment.replaceChild(0, fragment.firstChild!.copy(dropFromFragment(fragment.firstChild!.content, depth - 1, count)))
}

function addToFragment(fragment: Fragment, depth: number, content: Fragment): Fragment {
 if (depth == 0) return fragment.append(content)
 return fragment.replaceChild(fragment.childCount - 1,
                              fragment.lastChild!.copy(addToFragment(fragment.lastChild!.content, depth - 1, content)))
}

function contentAt(fragment: Fragment, depth: number) {
 for (let i = 0; i < depth; i++) fragment = fragment.firstChild!.content
 return fragment
}

function closeNodeStart(node: Node, openStart: number, openEnd: number) {
 if (openStart <= 0) return node
 let frag = node.content
 if (openStart > 1)
   frag = frag.replaceChild(0, closeNodeStart(frag.firstChild!, openStart - 1, frag.childCount == 1 ? openEnd - 1 : 0))
 if (openStart > 0) {
   frag = node.type.contentMatch.fillBefore(frag)!.append(frag)
   if (openEnd <= 0) frag = frag.append(node.type.contentMatch.matchFragment(frag)!.fillBefore(Fragment.empty, true)!)
 }
 return node.copy(frag)
}

function contentAfterFits($to: ResolvedPos, depth: number, type: NodeType, match: ContentMatch, open: boolean) {
 let node = $to.node(depth), index = open ? $to.indexAfter(depth) : $to.index(depth)
 if (index == node.childCount && !type.compatibleContent(node.type)) return null
 let fit = match.fillBefore(node.content, true, index)
 return fit && !invalidMarks(type, node.content, index) ? fit : null
}

function invalidMarks(type: NodeType, fragment: Fragment, start: number) {
 for (let i = start; i < fragment.childCount; i++)
   if (!type.allowsMarks(fragment.child(i).marks)) return true
 return false
}

function definesContent(type: NodeType) {
 return type.spec.defining || type.spec.definingForContent
}

export function replaceRange(tr: Transform, from: number, to: number, slice: Slice) {
 if (!slice.size) return tr.deleteRange(from, to)

 let $from = tr.doc.resolve(from), $to = tr.doc.resolve(to)
 if (fitsTrivially($from, $to, slice))
   return tr.step(new ReplaceStep(from, to, slice))

 let targetDepths = coveredDepths($from, $to)
 // Can't replace the whole document, so remove 0 if it's present
 if (targetDepths[targetDepths.length - 1] == 0) targetDepths.pop()
 // Negative numbers represent not expansion over the whole node at
 // that depth, but replacing from $from.before(-D) to $to.pos.
 let preferredTarget = -($from.depth + 1)
 targetDepths.unshift(preferredTarget)
 // This loop picks a preferred target depth, if one of the covering
 // depths is not outside of a defining node, and adds negative
 // depths for any depth that has $from at its start and does not
 // cross a defining node.
 for (let d = $from.depth, pos = $from.pos - 1; d > 0; d--, pos--) {
   let spec = $from.node(d).type.spec
   if (spec.defining || spec.definingAsContext || spec.isolating) break
   if (targetDepths.indexOf(d) > -1) preferredTarget = d
   else if ($from.before(d) == pos) targetDepths.splice(1, 0, -d)
 }
 // Try to fit each possible depth of the slice into each possible
 // target depth, starting with the preferred depths.
 let preferredTargetIndex = targetDepths.indexOf(preferredTarget)

 let leftNodes: Node[] = [], preferredDepth = slice.openStart
 for (let content = slice.content, i = 0;; i++) {
   let node = content.firstChild!
   leftNodes.push(node)
   if (i == slice.openStart) break
   content = node.content
 }

 // Back up preferredDepth to cover defining textblocks directly
 // above it, possibly skipping a non-defining textblock.
 for (let d = preferredDepth - 1; d >= 0; d--) {
   let leftNode = leftNodes[d], def = definesContent(leftNode.type)
   if (def && !leftNode.sameMarkup($from.node(Math.abs(preferredTarget) - 1))) preferredDepth = d
   else if (def || !leftNode.type.isTextblock) break
 }

 for (let j = slice.openStart; j >= 0; j--) {
   let openDepth = (j + preferredDepth + 1) % (slice.openStart + 1)
   let insert = leftNodes[openDepth]
   if (!insert) continue
   for (let i = 0; i < targetDepths.length; i++) {
     // Loop over possible expansion levels, starting with the
     // preferred one
     let targetDepth = targetDepths[(i + preferredTargetIndex) % targetDepths.length], expand = true
     if (targetDepth < 0) { expand = false; targetDepth = -targetDepth }
     let parent = $from.node(targetDepth - 1), index = $from.index(targetDepth - 1)
     if (parent.canReplaceWith(index, index, insert.type, insert.marks))
       return tr.replace($from.before(targetDepth), expand ? $to.after(targetDepth) : to,
                           new Slice(closeFragment(slice.content, 0, slice.openStart, openDepth),
                                     openDepth, slice.openEnd))
   }
 }

 let startSteps = tr.steps.length
 for (let i = targetDepths.length - 1; i >= 0; i--) {
   tr.replace(from, to, slice)
   if (tr.steps.length > startSteps) break
   let depth = targetDepths[i]
   if (depth < 0) continue
   from = $from.before(depth); to = $to.after(depth)
 }
}

function closeFragment(fragment: Fragment, depth: number, oldOpen: number, newOpen: number, parent?: Node) {
 if (depth < oldOpen) {
   let first = fragment.firstChild!
   fragment = fragment.replaceChild(0, first.copy(closeFragment(first.content, depth + 1, oldOpen, newOpen, first)))
 }
 if (depth > newOpen) {
   let match = parent!.contentMatchAt(0)!
   let start = match.fillBefore(fragment)!.append(fragment)
   fragment = start.append(match.matchFragment(start)!.fillBefore(Fragment.empty, true)!)
 }
 return fragment
}

export function replaceRangeWith(tr: Transform, from: number, to: number, node: Node) {
 if (!node.isInline && from == to && tr.doc.resolve(from).parent.content.size) {
   let point = insertPoint(tr.doc, from, node.type)
   if (point != null) from = to = point
 }
 tr.replaceRange(from, to, new Slice(Fragment.from(node), 0, 0))
}

export function deleteRange(tr: Transform, from: number, to: number) {
 let $from = tr.doc.resolve(from), $to = tr.doc.resolve(to)
 let covered = coveredDepths($from, $to)
 for (let i = 0; i < covered.length; i++) {
   let depth = covered[i], last = i == covered.length - 1
   if ((last && depth == 0) || $from.node(depth).type.contentMatch.validEnd)
     return tr.delete($from.start(depth), $to.end(depth))
   if (depth > 0 && (last || $from.node(depth - 1).canReplace($from.index(depth - 1), $to.indexAfter(depth - 1))))
     return tr.delete($from.before(depth), $to.after(depth))
 }
 for (let d = 1; d <= $from.depth && d <= $to.depth; d++) {
   if (from - $from.start(d) == $from.depth - d && to > $from.end(d) && $to.end(d) - to != $to.depth - d &&
       $from.start(d - 1) == $to.start(d - 1) && $from.node(d - 1).canReplace($from.index(d - 1), $to.index(d - 1)))
     return tr.delete($from.before(d), to)
 }
 tr.delete(from, to)
}

// Returns an array of all depths for which $from - $to spans the
// whole content of the nodes at that depth.
function coveredDepths($from: ResolvedPos, $to: ResolvedPos) {
 let result: number[] = [], minDepth = Math.min($from.depth, $to.depth)
 for (let d = minDepth; d >= 0; d--) {
   let start = $from.start(d)
   if (start < $from.pos - ($from.depth - d) ||
       $to.end(d) > $to.pos + ($to.depth - d) ||
       $from.node(d).type.spec.isolating ||
       $to.node(d).type.spec.isolating) break
   if (start == $to.start(d) ||
       (d == $from.depth && d == $to.depth && $from.parent.inlineContent && $to.parent.inlineContent &&
        d && $to.start(d - 1) == start - 1))
     result.push(d)
 }
 return result
}