overleaf/services/document-updater/app/js/sharejs/text-tp2.js
Jakob Ackermann 5862359ff0 Merge pull request #5518 from overleaf/jpa-no-empty
[misc] fix eslint violations for no-empty

GitOrigin-RevId: 8fc1688ac28ccf29b830ba43cd6091e64b5e3b07
2021-10-27 08:03:14 +00:00

499 lines
13 KiB
JavaScript

/* eslint-disable
no-cond-assign,
no-return-assign,
no-undef,
no-unused-vars,
*/
// TODO: This file was created by bulk-decaffeinate.
// Fix any style issues and re-enable lint.
/*
* decaffeinate suggestions:
* DS101: Remove unnecessary use of Array.from
* DS102: Remove unnecessary code created because of implicit returns
* DS103: Rewrite code to no longer use __guard__
* DS205: Consider reworking code to avoid use of IIFEs
* DS207: Consider shorter variations of null checks
* Full docs: https://github.com/decaffeinate/decaffeinate/blob/master/docs/suggestions.md
*/
// A TP2 implementation of text, following this spec:
// http://code.google.com/p/lightwave/source/browse/trunk/experimental/ot/README
//
// A document is made up of a string and a set of tombstones inserted throughout
// the string. For example, 'some ', (2 tombstones), 'string'.
//
// This is encoded in a document as: {s:'some string', t:[5, -2, 6]}
//
// Ops are lists of components which iterate over the whole document.
// Components are either:
// N: Skip N characters in the original document
// {i:'str'}: Insert 'str' at the current position in the document
// {i:N}: Insert N tombstones at the current position in the document
// {d:N}: Delete (tombstone) N characters at the current position in the document
//
// Eg: [3, {i:'hi'}, 5, {d:8}]
//
// Snapshots are lists with characters and tombstones. Characters are stored in strings
// and adjacent tombstones are flattened into numbers.
//
// Eg, the document: 'Hello .....world' ('.' denotes tombstoned (deleted) characters)
// would be represented by a document snapshot of ['Hello ', 5, 'world']
let append, appendDoc, takeDoc
const type = {
name: 'text-tp2',
tp2: true,
create() {
return { charLength: 0, totalLength: 0, positionCache: [], data: [] }
},
serialize(doc) {
if (!doc.data) {
throw new Error('invalid doc snapshot')
}
return doc.data
},
deserialize(data) {
const doc = type.create()
doc.data = data
for (const component of Array.from(data)) {
if (typeof component === 'string') {
doc.charLength += component.length
doc.totalLength += component.length
} else {
doc.totalLength += component
}
}
return doc
},
}
const checkOp = function (op) {
if (!Array.isArray(op)) {
throw new Error('Op must be an array of components')
}
let last = null
return (() => {
const result = []
for (const c of Array.from(op)) {
if (typeof c === 'object') {
if (c.i !== undefined) {
if (
(typeof c.i !== 'string' || !(c.i.length > 0)) &&
(typeof c.i !== 'number' || !(c.i > 0))
) {
throw new Error('Inserts must insert a string or a +ive number')
}
} else if (c.d !== undefined) {
if (typeof c.d !== 'number' || !(c.d > 0)) {
throw new Error('Deletes must be a +ive number')
}
} else {
throw new Error('Operation component must define .i or .d')
}
} else {
if (typeof c !== 'number') {
throw new Error('Op components must be objects or numbers')
}
if (!(c > 0)) {
throw new Error('Skip components must be a positive number')
}
if (typeof last === 'number') {
throw new Error('Adjacent skip components should be combined')
}
}
result.push((last = c))
}
return result
})()
}
// Take the next part from the specified position in a document snapshot.
// position = {index, offset}. It will be updated.
type._takeDoc = takeDoc = function (
doc,
position,
maxlength,
tombsIndivisible
) {
if (position.index >= doc.data.length) {
throw new Error('Operation goes past the end of the document')
}
const part = doc.data[position.index]
// peel off data[0]
const result =
typeof part === 'string'
? maxlength !== undefined
? part.slice(position.offset, position.offset + maxlength)
: part.slice(position.offset)
: maxlength === undefined || tombsIndivisible
? part - position.offset
: Math.min(maxlength, part - position.offset)
const resultLen = result.length || result
if ((part.length || part) - position.offset > resultLen) {
position.offset += resultLen
} else {
position.index++
position.offset = 0
}
return result
}
// Append a part to the end of a document
type._appendDoc = appendDoc = function (doc, p) {
if (p === 0 || p === '') {
return
}
if (typeof p === 'string') {
doc.charLength += p.length
doc.totalLength += p.length
} else {
doc.totalLength += p
}
const { data } = doc
if (data.length === 0) {
data.push(p)
} else if (typeof data[data.length - 1] === typeof p) {
data[data.length - 1] += p
} else {
data.push(p)
}
}
// Apply the op to the document. The document is not modified in the process.
type.apply = function (doc, op) {
if (
doc.totalLength === undefined ||
doc.charLength === undefined ||
doc.data.length === undefined
) {
throw new Error('Snapshot is invalid')
}
checkOp(op)
const newDoc = type.create()
const position = { index: 0, offset: 0 }
for (const component of Array.from(op)) {
let part, remainder
if (typeof component === 'number') {
remainder = component
while (remainder > 0) {
part = takeDoc(doc, position, remainder)
appendDoc(newDoc, part)
remainder -= part.length || part
}
} else if (component.i !== undefined) {
appendDoc(newDoc, component.i)
} else if (component.d !== undefined) {
remainder = component.d
while (remainder > 0) {
part = takeDoc(doc, position, remainder)
remainder -= part.length || part
}
appendDoc(newDoc, component.d)
}
}
return newDoc
}
// Append an op component to the end of the specified op.
// Exported for the randomOpGenerator.
type._append = append = function (op, component) {
if (
component === 0 ||
component.i === '' ||
component.i === 0 ||
component.d === 0
) {
return
}
if (op.length === 0) {
return op.push(component)
} else {
const last = op[op.length - 1]
if (typeof component === 'number' && typeof last === 'number') {
return (op[op.length - 1] += component)
} else if (
component.i !== undefined &&
last.i != null &&
typeof last.i === typeof component.i
) {
return (last.i += component.i)
} else if (component.d !== undefined && last.d != null) {
return (last.d += component.d)
} else {
return op.push(component)
}
}
}
// Makes 2 functions for taking components from the start of an op, and for peeking
// at the next op that could be taken.
const makeTake = function (op) {
// The index of the next component to take
let index = 0
// The offset into the component
let offset = 0
// Take up to length maxlength from the op. If maxlength is not defined, there is no max.
// If insertsIndivisible is true, inserts (& insert tombstones) won't be separated.
//
// Returns null when op is fully consumed.
const take = function (maxlength, insertsIndivisible) {
let current
if (index === op.length) {
return null
}
const e = op[index]
if (
typeof (current = e) === 'number' ||
typeof (current = e.i) === 'number' ||
(current = e.d) !== undefined
) {
let c
if (
maxlength == null ||
current - offset <= maxlength ||
(insertsIndivisible && e.i !== undefined)
) {
// Return the rest of the current element.
c = current - offset
++index
offset = 0
} else {
offset += maxlength
c = maxlength
}
if (e.i !== undefined) {
return { i: c }
} else if (e.d !== undefined) {
return { d: c }
} else {
return c
}
} else {
// Take from the inserted string
let result
if (
maxlength == null ||
e.i.length - offset <= maxlength ||
insertsIndivisible
) {
result = { i: e.i.slice(offset) }
++index
offset = 0
} else {
result = { i: e.i.slice(offset, offset + maxlength) }
offset += maxlength
}
return result
}
}
const peekType = () => op[index]
return [take, peekType]
}
// Find and return the length of an op component
const componentLength = function (component) {
if (typeof component === 'number') {
return component
} else if (typeof component.i === 'string') {
return component.i.length
} else {
// This should work because c.d and c.i must be +ive.
return component.d || component.i
}
}
// Normalize an op, removing all empty skips and empty inserts / deletes. Concatenate
// adjacent inserts and deletes.
type.normalize = function (op) {
const newOp = []
for (const component of Array.from(op)) {
append(newOp, component)
}
return newOp
}
// This is a helper method to transform and prune. goForwards is true for transform, false for prune.
const transformer = function (op, otherOp, goForwards, side) {
let component
checkOp(op)
checkOp(otherOp)
const newOp = []
const [take, peek] = Array.from(makeTake(op))
for (component of Array.from(otherOp)) {
let chunk
let length = componentLength(component)
if (component.i !== undefined) {
// Insert text or tombs
if (goForwards) {
// transform - insert skips over inserted parts
if (side === 'left') {
// The left insert should go first.
while (__guard__(peek(), x => x.i) !== undefined) {
append(newOp, take())
}
}
// In any case, skip the inserted text.
append(newOp, length)
} else {
// Prune. Remove skips for inserts.
while (length > 0) {
chunk = take(length, true)
if (chunk === null) {
throw new Error('The transformed op is invalid')
}
if (chunk.d !== undefined) {
throw new Error(
'The transformed op deletes locally inserted characters - it cannot be purged of the insert.'
)
}
if (typeof chunk === 'number') {
length -= chunk
} else {
append(newOp, chunk)
}
}
}
} else {
// Skip or delete
while (length > 0) {
chunk = take(length, true)
if (chunk === null) {
throw new Error(
'The op traverses more elements than the document has'
)
}
append(newOp, chunk)
if (!chunk.i) {
length -= componentLength(chunk)
}
}
}
}
// Append extras from op1
while ((component = take())) {
if (component.i === undefined) {
throw new Error(`Remaining fragments in the op: ${component}`)
}
append(newOp, component)
}
return newOp
}
// transform op1 by op2. Return transformed version of op1.
// op1 and op2 are unchanged by transform.
// side should be 'left' or 'right', depending on if op1.id <> op2.id. 'left' == client op.
type.transform = function (op, otherOp, side) {
if (side !== 'left' && side !== 'right') {
throw new Error(`side (${side}) should be 'left' or 'right'`)
}
return transformer(op, otherOp, true, side)
}
// Prune is the inverse of transform.
type.prune = (op, otherOp) => transformer(op, otherOp, false)
// Compose 2 ops into 1 op.
type.compose = function (op1, op2) {
let component
if (op1 === null || op1 === undefined) {
return op2
}
checkOp(op1)
checkOp(op2)
const result = []
const [take, _] = Array.from(makeTake(op1))
for (component of Array.from(op2)) {
let chunk, length
if (typeof component === 'number') {
// Skip
// Just copy from op1.
length = component
while (length > 0) {
chunk = take(length)
if (chunk === null) {
throw new Error(
'The op traverses more elements than the document has'
)
}
append(result, chunk)
length -= componentLength(chunk)
}
} else if (component.i !== undefined) {
// Insert
append(result, { i: component.i })
} else {
// Delete
length = component.d
while (length > 0) {
chunk = take(length)
if (chunk === null) {
throw new Error(
'The op traverses more elements than the document has'
)
}
const chunkLength = componentLength(chunk)
if (chunk.i !== undefined) {
append(result, { i: chunkLength })
} else {
append(result, { d: chunkLength })
}
length -= chunkLength
}
}
}
// Append extras from op1
while ((component = take())) {
if (component.i === undefined) {
throw new Error(`Remaining fragments in op1: ${component}`)
}
append(result, component)
}
return result
}
if (typeof WEB !== 'undefined' && WEB !== null) {
exports.types['text-tp2'] = type
} else {
module.exports = type
}
function __guard__(value, transform) {
return typeof value !== 'undefined' && value !== null
? transform(value)
: undefined
}