overleaf/services/document-updater/app/js/sharejs/text.js

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/* eslint-disable
no-return-assign,
no-undef,
*/
// 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
* DS207: Consider shorter variations of null checks
* Full docs: https://github.com/decaffeinate/decaffeinate/blob/master/docs/suggestions.md
*/
// A simple text implementation
//
// Operations are lists of components.
// Each component either inserts or deletes at a specified position in the document.
//
// Components are either:
// {i:'str', p:100}: Insert 'str' at position 100 in the document
// {d:'str', p:100}: Delete 'str' at position 100 in the document
//
// Components in an operation are executed sequentially, so the position of components
// assumes previous components have already executed.
//
// Eg: This op:
// [{i:'abc', p:0}]
// is equivalent to this op:
// [{i:'a', p:0}, {i:'b', p:1}, {i:'c', p:2}]
// NOTE: The global scope here is shared with other sharejs files when built with closure.
// Be careful what ends up in your namespace.
let append, transformComponent
const text = {}
text.name = 'text'
text.create = () => ''
const strInject = (s1, pos, s2) => s1.slice(0, pos) + s2 + s1.slice(pos)
const checkValidComponent = function (c) {
if (typeof c.p !== 'number') {
throw new Error('component missing position field')
}
const iType = typeof c.i
const dType = typeof c.d
if (!((iType === 'string') ^ (dType === 'string'))) {
throw new Error('component needs an i or d field')
}
if (!(c.p >= 0)) {
throw new Error('position cannot be negative')
}
}
const checkValidOp = function (op) {
for (const c of Array.from(op)) {
checkValidComponent(c)
}
return true
}
text.apply = function (snapshot, op) {
checkValidOp(op)
for (const component of Array.from(op)) {
if (component.i != null) {
snapshot = strInject(snapshot, component.p, component.i)
} else {
const deleted = snapshot.slice(
component.p,
component.p + component.d.length
)
if (component.d !== deleted) {
throw new Error(
`Delete component '${component.d}' does not match deleted text '${deleted}'`
)
}
snapshot =
snapshot.slice(0, component.p) +
snapshot.slice(component.p + component.d.length)
}
}
return snapshot
}
// Exported for use by the random op generator.
//
// For simplicity, this version of append does not compress adjacent inserts and deletes of
// the same text. It would be nice to change that at some stage.
text._append = append = function (newOp, c) {
if (c.i === '' || c.d === '') {
return
}
if (newOp.length === 0) {
return newOp.push(c)
} else {
const last = newOp[newOp.length - 1]
// Compose the insert into the previous insert if possible
if (
last.i != null &&
c.i != null &&
last.p <= c.p &&
c.p <= last.p + last.i.length
) {
return (newOp[newOp.length - 1] = {
i: strInject(last.i, c.p - last.p, c.i),
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p: last.p,
})
} else if (
last.d != null &&
c.d != null &&
c.p <= last.p &&
last.p <= c.p + c.d.length
) {
return (newOp[newOp.length - 1] = {
d: strInject(c.d, last.p - c.p, last.d),
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p: c.p,
})
} else {
return newOp.push(c)
}
}
}
text.compose = function (op1, op2) {
checkValidOp(op1)
checkValidOp(op2)
const newOp = op1.slice()
for (const c of Array.from(op2)) {
append(newOp, c)
}
return newOp
}
// Attempt to compress the op components together 'as much as possible'.
// This implementation preserves order and preserves create/delete pairs.
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text.compress = op => text.compose([], op)
text.normalize = function (op) {
const newOp = []
// Normalize should allow ops which are a single (unwrapped) component:
// {i:'asdf', p:23}.
// There's no good way to test if something is an array:
// http://perfectionkills.com/instanceof-considered-harmful-or-how-to-write-a-robust-isarray/
// so this is probably the least bad solution.
if (op.i != null || op.p != null) {
op = [op]
}
for (const c of Array.from(op)) {
if (c.p == null) {
c.p = 0
}
append(newOp, c)
}
return newOp
}
// This helper method transforms a position by an op component.
//
// If c is an insert, insertAfter specifies whether the transform
// is pushed after the insert (true) or before it (false).
//
// insertAfter is optional for deletes.
const transformPosition = function (pos, c, insertAfter) {
if (c.i != null) {
if (c.p < pos || (c.p === pos && insertAfter)) {
return pos + c.i.length
} else {
return pos
}
} else {
// I think this could also be written as: Math.min(c.p, Math.min(c.p - otherC.p, otherC.d.length))
// but I think its harder to read that way, and it compiles using ternary operators anyway
// so its no slower written like this.
if (pos <= c.p) {
return pos
} else if (pos <= c.p + c.d.length) {
return c.p
} else {
return pos - c.d.length
}
}
}
// Helper method to transform a cursor position as a result of an op.
//
// Like transformPosition above, if c is an insert, insertAfter specifies whether the cursor position
// is pushed after an insert (true) or before it (false).
text.transformCursor = function (position, op, side) {
const insertAfter = side === 'right'
for (const c of Array.from(op)) {
position = transformPosition(position, c, insertAfter)
}
return position
}
// Transform an op component by another op component. Asymmetric.
// The result will be appended to destination.
//
// exported for use in JSON type
text._tc = transformComponent = function (dest, c, otherC, side) {
checkValidOp([c])
checkValidOp([otherC])
if (c.i != null) {
append(dest, {
i: c.i,
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p: transformPosition(c.p, otherC, side === 'right'),
})
} else {
// Delete
if (otherC.i != null) {
// delete vs insert
let s = c.d
if (c.p < otherC.p) {
append(dest, { d: s.slice(0, otherC.p - c.p), p: c.p })
s = s.slice(otherC.p - c.p)
}
if (s !== '') {
append(dest, { d: s, p: c.p + otherC.i.length })
}
} else {
// Delete vs delete
if (c.p >= otherC.p + otherC.d.length) {
append(dest, { d: c.d, p: c.p - otherC.d.length })
} else if (c.p + c.d.length <= otherC.p) {
append(dest, c)
} else {
// They overlap somewhere.
const newC = { d: '', p: c.p }
if (c.p < otherC.p) {
newC.d = c.d.slice(0, otherC.p - c.p)
}
if (c.p + c.d.length > otherC.p + otherC.d.length) {
newC.d += c.d.slice(otherC.p + otherC.d.length - c.p)
}
// This is entirely optional - just for a check that the deleted
// text in the two ops matches
const intersectStart = Math.max(c.p, otherC.p)
const intersectEnd = Math.min(
c.p + c.d.length,
otherC.p + otherC.d.length
)
const cIntersect = c.d.slice(intersectStart - c.p, intersectEnd - c.p)
const otherIntersect = otherC.d.slice(
intersectStart - otherC.p,
intersectEnd - otherC.p
)
if (cIntersect !== otherIntersect) {
throw new Error(
'Delete ops delete different text in the same region of the document'
)
}
if (newC.d !== '') {
// This could be rewritten similarly to insert v delete, above.
newC.p = transformPosition(newC.p, otherC)
append(dest, newC)
}
}
}
}
return dest
}
const invertComponent = function (c) {
if (c.i != null) {
return { d: c.i, p: c.p }
} else {
return { i: c.d, p: c.p }
}
}
// No need to use append for invert, because the components won't be able to
// cancel with one another.
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text.invert = op =>
Array.from(op.slice().reverse()).map(c => invertComponent(c))
if (typeof WEB !== 'undefined' && WEB !== null) {
if (!exports.types) {
exports.types = {}
}
// This is kind of awful - come up with a better way to hook this helper code up.
bootstrapTransform(text, transformComponent, checkValidOp, append)
// [] is used to prevent closure from renaming types.text
exports.types.text = text
} else {
module.exports = text
// The text type really shouldn't need this - it should be possible to define
// an efficient transform function by making a sort of transform map and passing each
// op component through it.
require('./helpers').bootstrapTransform(
text,
transformComponent,
checkValidOp,
append
)
}