basics of range based quotations

src/structs/ContentType.js

@@ -113,13 +113,15 @@ export class ContentType {
       // when removing weak links, remove references to them 
       // from type they're pointing to
       const type = /** @type {WeakLink<any>} */ (this.type);
-      if (type._linkedItem !== null && !type._linkedItem.deleted) {
+      for (let item = type._firstItem; item !== null; item = item.right) {
-        const item = /** @type {Item} */ (type._linkedItem)
         if (item.linked) {
           unlinkFrom(transaction, item, type)
         }
-        type._linkedItem = null
+        if (item === type._lastItem) {
+          break;
+        }
       }
+      type._firstItem = type._lastItem = null
     }
 
     let item = this.type._start

src/structs/Item.js

@@ -396,9 +396,15 @@ export class Item extends AbstractStruct {
     }
     if (this.content.constructor === ContentType && /** @type {ContentType} */ (this.content).type.constructor === YWeakLink) {
       // make sure that linked content is integrated first
-      const linkSource = /** @type {any} */ (this.content).type._id
+      const content = /** @type {ContentType} */ (this.content)
-      if (linkSource.clock >= getState(store, linkSource.client)) {
+      const link = /** @type {YWeakLink<any>} */ (content.type)
-        return linkSource.client
+      const start = link._quoteStart.item
+      if (start !== null && start.clock >= getState(store, start.client)) {
+        return start.client
+      }
+      const end = link._quoteEnd.item
+      if (end !== null && end.clock >= getState(store, end.client)) {
+        return end.client
       }
     }
 

src/types/YArray.js

@@ -215,7 +215,7 @@ export class YArray extends AbstractType {
         return arrayWeakLink(transaction, this, index)
       })
     } else {
-      throw new Error('todo')
+      throw new Error('cannot create a link to an YArray that has not been integrated into YDoc')
     }
   }
 

src/types/YWeakLink.js

@@ -10,7 +10,8 @@ import {
   callTypeObservers,
   YWeakLinkRefID,
   writeID,
-  readID
+  readID,
+  RelativePosition
 } from "../internals.js"
 
 /**
@@ -36,13 +37,26 @@ export class YWeakLinkEvent extends YEvent {
  */
 export class YWeakLink extends AbstractType {
   /**
-    * @param {ID} id
+    * @param {RelativePosition} start
-    * @param {Item|GC|null} item
+    * @param {RelativePosition} end
+    * @param {Item|null} firstItem
+    * @param {Item|null} lastItem
     */
-  constructor(id, item) {
+  constructor(start, end, firstItem, lastItem) {
     super()
-    this._id = id
+    this._quoteStart = start
-    this._linkedItem = item
+    this._quoteEnd = end
+    this._firstItem = firstItem
+    this._lastItem = lastItem
+  }
+
+  /**
+   * Check if current link contains only a single element.
+   * 
+   * @returns {boolean}
+   */
+  isSingle() {
+    return this._quoteStart.item === this._quoteEnd.item
   }
   
   /**
@@ -51,21 +65,40 @@ export class YWeakLink extends AbstractType {
    * @return {T|undefined}
    */
   deref() {
-    if (this._linkedItem !== null && this._linkedItem.constructor === Item) {
+    if (this._firstItem !== null) {
-      let item = this._linkedItem
+      let item = this._firstItem
       if (item.parentSub !== null) {
-        // for map types go to the most recent one
         while (item.right !== null) {
           item = item.right
         }
-        this._linkedItem = item
+        // we don't support quotations over maps
+        this._firstItem = item
       }
-      if (!item.deleted) {
+      if (!this._firstItem.deleted) {
-        return item.content.getContent()[0]
+        return this._firstItem.content.getContent()[0]
       }
     }
+
     return undefined;
   }
+  
+  /**
+   * Returns an array of references to all elements quoted by current weak link.
+   * 
+   * @return {Array<any>}
+   */
+  unqote() {
+    let result = /** @type {Array<any>} */ ([])
+    let item = this._firstItem
+    //TODO: moved elements
+    while (item !== null && item !== this._lastItem) {
+      if (!item.deleted) {
+        result = result.concat(item.content.getContent())
+      }
+      item = item.right
+    }
+    return result
+  }
 
   /**
    * Integrate this type into the Yjs instance.
@@ -84,19 +117,25 @@ export class YWeakLink extends AbstractType {
         // link may refer to a single element in multi-element block
         // in such case we need to cut of the linked element into a
         // separate block
-        let sourceItem = this._linkedItem !== null ? this._linkedItem : getItemCleanStart(transaction, this._id)
+        let firstItem = this._firstItem !== null ? this._firstItem : getItemCleanStart(transaction, /** @type {ID} */ (this._quoteStart.item))
-        if (sourceItem.constructor === Item && sourceItem.parentSub !== null) {
+        let lastItem = this._lastItem !== null ? this._lastItem : getItemCleanEnd(transaction, y.store, /** @type {ID} */(this._quoteEnd.item))
+        if (firstItem.parentSub !== null) {
           // for maps, advance to most recent item
-          while (sourceItem.right !== null) {
+          while (firstItem.right !== null) {
-            sourceItem = sourceItem.right
+            firstItem = firstItem.right
           }
+          lastItem = firstItem
         }
-        if (!sourceItem.deleted && sourceItem.length > 1) {
+        this._firstItem = firstItem
-          sourceItem = getItemCleanEnd(transaction, transaction.doc.store, createID(sourceItem.id.client, sourceItem.id.clock + 1))
+        this._lastItem = lastItem
-        }
+        
-        this._linkedItem = sourceItem
+        /** @type {Item|null} */
-        if (!sourceItem.deleted) {
+        let item = firstItem
-          createLink(transaction, /** @type {Item} */ (sourceItem), this)
+        for (; item !== null; item = item.right) {
+          createLink(transaction, item, this)
+          if (item === lastItem) {
+            break;
+          }
         }
       })
     }
@@ -106,14 +145,14 @@ export class YWeakLink extends AbstractType {
    * @return {YWeakLink<T>}
    */
   _copy () {
-    return new YWeakLink(this._id, this._linkedItem)
+    return new YWeakLink(this._quoteStart, this._quoteEnd, this._firstItem, this._lastItem)
   }
 
   /**
    * @return {YWeakLink<T>}
    */
   clone () {
-    return new YWeakLink(this._id, this._linkedItem)
+    return new YWeakLink(this._quoteStart, this._quoteEnd, this._firstItem, this._lastItem)
   }
 
   /**
@@ -132,9 +171,13 @@ export class YWeakLink extends AbstractType {
    */
   _write (encoder) {
     encoder.writeTypeRef(YWeakLinkRefID)
-    const flags = 0 // flags that could be used in the future
+    const isSingle = this.isSingle()
-    encoding.writeUint8(encoder.restEncoder, flags)
+    const info =  (isSingle ? 0 : 1) | (this._quoteStart.assoc >= 0 ? 2 : 0) | (this._quoteEnd.assoc >= 0 ? 4 :0)
-    writeID(encoder.restEncoder, this._id)
+    encoding.writeUint8(encoder.restEncoder, info)
+    writeID(encoder.restEncoder, /** @type {ID} */ (this._quoteStart.item))
+    if (!isSingle) {
+      writeID(encoder.restEncoder, /** @type {ID} */ (this._quoteEnd.item))
+    }
   }
 }
 
@@ -144,9 +187,14 @@ export class YWeakLink extends AbstractType {
  * @return {YWeakLink<any>}
  */
 export const readYWeakLink = decoder => {
-  const flags = decoding.readUint8(decoder.restDecoder)
+  const info = decoding.readUint8(decoder.restDecoder)
-  const id = readID(decoder.restDecoder)
+  const isSingle = (info & 1) !== 1
-  return new YWeakLink(id, null)
+  const startAssoc = (info & 2) === 2 ? 0 : -1
+  const endAssoc = (info & 4) === 4 ? 0 : -1
+  const startID = readID(decoder.restDecoder)
+  const start = new RelativePosition(null, null, startID, startAssoc)
+  const end = new RelativePosition(null, null, isSingle ? startID : readID(decoder.restDecoder), endAssoc)
+  return new YWeakLink(start, end, null, null)
 }
 
 const lengthExceeded = error.create('Length exceeded!')
@@ -159,27 +207,43 @@ const lengthExceeded = error.create('Length exceeded!')
  * @param {number} index
  * @return {YWeakLink<any>}
  */
-export const arrayWeakLink = (transaction, parent, index) => {
+export const arrayWeakLink = (transaction, parent, index, length = 1) => {
-  let item = parent._start
+  let startItem = parent._start
-  for (; item !== null; item = item.right) {
+  for (;startItem !== null; startItem = startItem.right) {
-    if (!item.deleted && item.countable) {
+    if (!startItem.deleted && startItem.countable) {
-      if (index < item.length) {
+      if (index < startItem.length) {
         if (index > 0) {
-            item = getItemCleanStart(transaction, createID(item.id.client, item.id.clock + index))
+            startItem = getItemCleanStart(transaction, createID(startItem.id.client, startItem.id.clock + index))
         }
-        if (item.length > 1) {
+        break;
-            item = getItemCleanEnd(transaction, transaction.doc.store, createID(item.id.client, item.id.clock))
-        }
-        const link = new YWeakLink(item.id, item)
-        if (parent.doc !== null) {
-          const source = /** @type {Item} */ (item)
-          transact(parent.doc, (transaction) => {
-            createLink(transaction, source, link)
-          })
-        }
-        return link
       }
-      index -= item.length
+      index -= startItem.length
+    }
+  }
+
+  if (startItem !== null) {
+    let endItem =  startItem
+    let remaining = length
+    for (;endItem !== null && endItem.right !== null && endItem.length > remaining; endItem = endItem.right) {
+      // iterate over the items to reach the last block in the quoted range
+      remaining -= endItem.length
+    }
+    if (endItem.length >= remaining) {
+      endItem = getItemCleanEnd(transaction, transaction.doc.store, createID(startItem.id.client, startItem.id.clock + remaining - 1))
+      const start = new RelativePosition(null, null, startItem.id, 0)
+      const end = new RelativePosition(null, null, endItem.lastId, -1)
+      const link = new YWeakLink(start, end, startItem, endItem)
+      if (parent.doc !== null) {
+        transact(parent.doc, (transaction) => {
+          for (let item = link._firstItem; item !== null; item = item = item.right) {
+            createLink(transaction, item, link)
+            if (item === link._lastItem) {
+              break;
+            }
+          }
+        })
+      }
+      return link
     }
   }
 
@@ -196,7 +260,9 @@ export const arrayWeakLink = (transaction, parent, index) => {
 export const mapWeakLink = (parent, key) => {
   const item = parent._map.get(key)
   if (item !== undefined) {
-    const link = new YWeakLink(item.id, item)
+    const start = new RelativePosition(null, null, item.id, 0)
+    const end = new RelativePosition(null, null, item.id, -1)
+    const link = new YWeakLink(start, end, item, item)
     if (parent.doc !== null) {
       transact(parent.doc, (transaction) => {
         createLink(transaction, item, link)