mirror of
https://github.com/overleaf/overleaf.git
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218 lines
6.7 KiB
CoffeeScript
218 lines
6.7 KiB
CoffeeScript
strInject = (s1, pos, s2) -> s1[...pos] + s2 + s1[pos..]
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strRemove = (s1, pos, length) -> s1[...pos] + s1[(pos + length)..]
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diff_match_patch = require("../lib/diff_match_patch").diff_match_patch
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dmp = new diff_match_patch()
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module.exports = UpdateCompressor =
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NOOP: "noop"
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# Updates come from the doc updater in format
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# {
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# op: [ { ... op1 ... }, { ... op2 ... } ]
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# meta: { ts: ..., user_id: ... }
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# }
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# but it's easier to work with on op per update, so convert these updates to
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# our compressed format
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# [{
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# op: op1
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# meta: { start_ts: ... , end_ts: ..., user_id: ... }
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# }, {
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# op: op2
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# meta: { start_ts: ... , end_ts: ..., user_id: ... }
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# }]
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convertToSingleOpUpdates: (updates) ->
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splitUpdates = []
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for update in updates
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# Reject any non-insert or delete ops, i.e. comments
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ops = update.op.filter (o) -> o.i? or o.d?
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if ops.length == 0
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splitUpdates.push
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op: UpdateCompressor.NOOP
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meta:
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start_ts: update.meta.start_ts or update.meta.ts
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end_ts: update.meta.end_ts or update.meta.ts
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user_id: update.meta.user_id
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v: update.v
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else
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for op in ops
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splitUpdates.push
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op: op
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meta:
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start_ts: update.meta.start_ts or update.meta.ts
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end_ts: update.meta.end_ts or update.meta.ts
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user_id: update.meta.user_id
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v: update.v
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return splitUpdates
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concatUpdatesWithSameVersion: (updates) ->
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concattedUpdates = []
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for update in updates
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lastUpdate = concattedUpdates[concattedUpdates.length - 1]
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if lastUpdate? and lastUpdate.v == update.v
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lastUpdate.op.push update.op unless update.op == UpdateCompressor.NOOP
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else
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nextUpdate =
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op: []
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meta: update.meta
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v: update.v
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nextUpdate.op.push update.op unless update.op == UpdateCompressor.NOOP
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concattedUpdates.push nextUpdate
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return concattedUpdates
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compressRawUpdates: (lastPreviousUpdate, rawUpdates) ->
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if lastPreviousUpdate?.op?.length > 1
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# if the last previous update was an array op, don't compress onto it.
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# The avoids cases where array length changes but version number doesn't
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return [lastPreviousUpdate].concat UpdateCompressor.compressRawUpdates(null,rawUpdates)
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if lastPreviousUpdate?
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rawUpdates = [lastPreviousUpdate].concat(rawUpdates)
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updates = UpdateCompressor.convertToSingleOpUpdates(rawUpdates)
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updates = UpdateCompressor.compressUpdates(updates)
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return UpdateCompressor.concatUpdatesWithSameVersion(updates)
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compressUpdates: (updates) ->
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return [] if updates.length == 0
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compressedUpdates = [updates.shift()]
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for update in updates
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lastCompressedUpdate = compressedUpdates.pop()
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if lastCompressedUpdate?
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compressedUpdates = compressedUpdates.concat UpdateCompressor._concatTwoUpdates lastCompressedUpdate, update
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else
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compressedUpdates.push update
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return compressedUpdates
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MAX_TIME_BETWEEN_UPDATES: oneMinute = 60 * 1000
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MAX_UPDATE_SIZE: twoMegabytes = 2* 1024 * 1024
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_concatTwoUpdates: (firstUpdate, secondUpdate) ->
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firstUpdate =
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op: firstUpdate.op
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meta:
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user_id: firstUpdate.meta.user_id or null
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start_ts: firstUpdate.meta.start_ts or firstUpdate.meta.ts
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end_ts: firstUpdate.meta.end_ts or firstUpdate.meta.ts
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v: firstUpdate.v
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secondUpdate =
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op: secondUpdate.op
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meta:
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user_id: secondUpdate.meta.user_id or null
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start_ts: secondUpdate.meta.start_ts or secondUpdate.meta.ts
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end_ts: secondUpdate.meta.end_ts or secondUpdate.meta.ts
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v: secondUpdate.v
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if firstUpdate.meta.user_id != secondUpdate.meta.user_id
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return [firstUpdate, secondUpdate]
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if secondUpdate.meta.start_ts - firstUpdate.meta.end_ts > UpdateCompressor.MAX_TIME_BETWEEN_UPDATES
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return [firstUpdate, secondUpdate]
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firstOp = firstUpdate.op
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secondOp = secondUpdate.op
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firstSize = firstOp.i?.length or firstOp.d?.length
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secondSize = secondOp.i?.length or secondOp.d?.length
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# Two inserts
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if firstOp.i? and secondOp.i? and firstOp.p <= secondOp.p <= (firstOp.p + firstOp.i.length) and firstSize + secondSize < UpdateCompressor.MAX_UPDATE_SIZE
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return [
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meta:
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start_ts: firstUpdate.meta.start_ts
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end_ts: secondUpdate.meta.end_ts
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user_id: firstUpdate.meta.user_id
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op:
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p: firstOp.p
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i: strInject(firstOp.i, secondOp.p - firstOp.p, secondOp.i)
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v: secondUpdate.v
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]
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# Two deletes
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else if firstOp.d? and secondOp.d? and secondOp.p <= firstOp.p <= (secondOp.p + secondOp.d.length) and firstSize + secondSize < UpdateCompressor.MAX_UPDATE_SIZE
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return [
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meta:
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start_ts: firstUpdate.meta.start_ts
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end_ts: secondUpdate.meta.end_ts
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user_id: firstUpdate.meta.user_id
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op:
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p: secondOp.p
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d: strInject(secondOp.d, firstOp.p - secondOp.p, firstOp.d)
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v: secondUpdate.v
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]
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# An insert and then a delete
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else if firstOp.i? and secondOp.d? and firstOp.p <= secondOp.p <= (firstOp.p + firstOp.i.length)
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offset = secondOp.p - firstOp.p
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insertedText = firstOp.i.slice(offset, offset + secondOp.d.length)
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# Only trim the insert when the delete is fully contained within in it
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if insertedText == secondOp.d
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insert = strRemove(firstOp.i, offset, secondOp.d.length)
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return [
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meta:
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start_ts: firstUpdate.meta.start_ts
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end_ts: secondUpdate.meta.end_ts
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user_id: firstUpdate.meta.user_id
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op:
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p: firstOp.p
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i: insert
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v: secondUpdate.v
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]
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else
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# This will only happen if the delete extends outside the insert
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return [firstUpdate, secondUpdate]
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# A delete then an insert at the same place, likely a copy-paste of a chunk of content
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else if firstOp.d? and secondOp.i? and firstOp.p == secondOp.p
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offset = firstOp.p
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diff_ops = @diffAsShareJsOps(firstOp.d, secondOp.i)
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if diff_ops.length == 0
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return [{ # Noop
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meta:
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start_ts: firstUpdate.meta.start_ts
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end_ts: secondUpdate.meta.end_ts
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user_id: firstUpdate.meta.user_id
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op:
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p: firstOp.p
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i: ""
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v: secondUpdate.v
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}]
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else
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return diff_ops.map (op) ->
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op.p += offset
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return {
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meta:
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start_ts: firstUpdate.meta.start_ts
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end_ts: secondUpdate.meta.end_ts
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user_id: firstUpdate.meta.user_id
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op: op
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v: secondUpdate.v
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}
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else
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return [firstUpdate, secondUpdate]
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ADDED: 1
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REMOVED: -1
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UNCHANGED: 0
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diffAsShareJsOps: (before, after, callback = (error, ops) ->) ->
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diffs = dmp.diff_main(before, after)
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dmp.diff_cleanupSemantic(diffs)
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ops = []
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position = 0
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for diff in diffs
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type = diff[0]
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content = diff[1]
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if type == @ADDED
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ops.push
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i: content
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p: position
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position += content.length
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else if type == @REMOVED
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ops.push
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d: content
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p: position
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else if type == @UNCHANGED
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position += content.length
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else
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throw "Unknown type"
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return ops
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