mirror of
https://github.com/overleaf/overleaf.git
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314 lines
8.6 KiB
JavaScript
314 lines
8.6 KiB
JavaScript
/* eslint-disable
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camelcase,
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no-return-assign,
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no-undef,
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*/
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// TODO: This file was created by bulk-decaffeinate.
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// Fix any style issues and re-enable lint.
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/*
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* decaffeinate suggestions:
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* DS101: Remove unnecessary use of Array.from
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* DS102: Remove unnecessary code created because of implicit returns
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* DS207: Consider shorter variations of null checks
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* Full docs: https://github.com/decaffeinate/decaffeinate/blob/master/docs/suggestions.md
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*/
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// A simple text implementation
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//
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// Operations are lists of components.
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// Each component either inserts or deletes at a specified position in the document.
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//
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// Components are either:
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// {i:'str', p:100}: Insert 'str' at position 100 in the document
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// {d:'str', p:100}: Delete 'str' at position 100 in the document
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//
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// Components in an operation are executed sequentially, so the position of components
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// assumes previous components have already executed.
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//
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// Eg: This op:
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// [{i:'abc', p:0}]
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// is equivalent to this op:
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// [{i:'a', p:0}, {i:'b', p:1}, {i:'c', p:2}]
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// NOTE: The global scope here is shared with other sharejs files when built with closure.
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// Be careful what ends up in your namespace.
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let append, transformComponent
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const text = {}
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text.name = 'text'
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text.create = () => ''
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const strInject = (s1, pos, s2) => s1.slice(0, pos) + s2 + s1.slice(pos)
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const checkValidComponent = function (c) {
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if (typeof c.p !== 'number') {
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throw new Error('component missing position field')
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}
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const i_type = typeof c.i
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const d_type = typeof c.d
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if (!((i_type === 'string') ^ (d_type === 'string'))) {
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throw new Error('component needs an i or d field')
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}
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if (!(c.p >= 0)) {
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throw new Error('position cannot be negative')
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}
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}
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const checkValidOp = function (op) {
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for (const c of Array.from(op)) {
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checkValidComponent(c)
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}
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return true
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}
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text.apply = function (snapshot, op) {
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checkValidOp(op)
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for (const component of Array.from(op)) {
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if (component.i != null) {
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snapshot = strInject(snapshot, component.p, component.i)
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} else {
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const deleted = snapshot.slice(
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component.p,
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component.p + component.d.length
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)
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if (component.d !== deleted) {
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throw new Error(
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`Delete component '${component.d}' does not match deleted text '${deleted}'`
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)
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}
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snapshot =
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snapshot.slice(0, component.p) +
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snapshot.slice(component.p + component.d.length)
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}
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}
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return snapshot
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}
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// Exported for use by the random op generator.
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//
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// For simplicity, this version of append does not compress adjacent inserts and deletes of
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// the same text. It would be nice to change that at some stage.
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text._append = append = function (newOp, c) {
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if (c.i === '' || c.d === '') {
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return
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}
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if (newOp.length === 0) {
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return newOp.push(c)
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} else {
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const last = newOp[newOp.length - 1]
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// Compose the insert into the previous insert if possible
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if (
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last.i != null &&
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c.i != null &&
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last.p <= c.p &&
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c.p <= last.p + last.i.length
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) {
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return (newOp[newOp.length - 1] = {
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i: strInject(last.i, c.p - last.p, c.i),
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p: last.p,
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})
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} else if (
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last.d != null &&
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c.d != null &&
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c.p <= last.p &&
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last.p <= c.p + c.d.length
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) {
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return (newOp[newOp.length - 1] = {
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d: strInject(c.d, last.p - c.p, last.d),
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p: c.p,
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})
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} else {
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return newOp.push(c)
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}
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}
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}
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text.compose = function (op1, op2) {
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checkValidOp(op1)
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checkValidOp(op2)
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const newOp = op1.slice()
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for (const c of Array.from(op2)) {
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append(newOp, c)
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}
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return newOp
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}
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// Attempt to compress the op components together 'as much as possible'.
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// This implementation preserves order and preserves create/delete pairs.
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text.compress = op => text.compose([], op)
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text.normalize = function (op) {
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const newOp = []
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// Normalize should allow ops which are a single (unwrapped) component:
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// {i:'asdf', p:23}.
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// There's no good way to test if something is an array:
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// http://perfectionkills.com/instanceof-considered-harmful-or-how-to-write-a-robust-isarray/
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// so this is probably the least bad solution.
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if (op.i != null || op.p != null) {
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op = [op]
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}
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for (const c of Array.from(op)) {
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if (c.p == null) {
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c.p = 0
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}
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append(newOp, c)
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}
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return newOp
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}
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// This helper method transforms a position by an op component.
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//
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// If c is an insert, insertAfter specifies whether the transform
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// is pushed after the insert (true) or before it (false).
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//
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// insertAfter is optional for deletes.
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const transformPosition = function (pos, c, insertAfter) {
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if (c.i != null) {
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if (c.p < pos || (c.p === pos && insertAfter)) {
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return pos + c.i.length
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} else {
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return pos
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}
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} else {
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// I think this could also be written as: Math.min(c.p, Math.min(c.p - otherC.p, otherC.d.length))
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// but I think its harder to read that way, and it compiles using ternary operators anyway
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// so its no slower written like this.
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if (pos <= c.p) {
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return pos
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} else if (pos <= c.p + c.d.length) {
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return c.p
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} else {
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return pos - c.d.length
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}
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}
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}
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// Helper method to transform a cursor position as a result of an op.
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//
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// Like transformPosition above, if c is an insert, insertAfter specifies whether the cursor position
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// is pushed after an insert (true) or before it (false).
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text.transformCursor = function (position, op, side) {
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const insertAfter = side === 'right'
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for (const c of Array.from(op)) {
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position = transformPosition(position, c, insertAfter)
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}
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return position
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}
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// Transform an op component by another op component. Asymmetric.
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// The result will be appended to destination.
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//
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// exported for use in JSON type
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text._tc = transformComponent = function (dest, c, otherC, side) {
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checkValidOp([c])
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checkValidOp([otherC])
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if (c.i != null) {
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append(dest, {
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i: c.i,
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p: transformPosition(c.p, otherC, side === 'right'),
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})
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} else {
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// Delete
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if (otherC.i != null) {
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// delete vs insert
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let s = c.d
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if (c.p < otherC.p) {
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append(dest, { d: s.slice(0, otherC.p - c.p), p: c.p })
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s = s.slice(otherC.p - c.p)
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}
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if (s !== '') {
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append(dest, { d: s, p: c.p + otherC.i.length })
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}
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} else {
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// Delete vs delete
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if (c.p >= otherC.p + otherC.d.length) {
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append(dest, { d: c.d, p: c.p - otherC.d.length })
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} else if (c.p + c.d.length <= otherC.p) {
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append(dest, c)
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} else {
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// They overlap somewhere.
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const newC = { d: '', p: c.p }
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if (c.p < otherC.p) {
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newC.d = c.d.slice(0, otherC.p - c.p)
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}
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if (c.p + c.d.length > otherC.p + otherC.d.length) {
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newC.d += c.d.slice(otherC.p + otherC.d.length - c.p)
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}
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// This is entirely optional - just for a check that the deleted
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// text in the two ops matches
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const intersectStart = Math.max(c.p, otherC.p)
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const intersectEnd = Math.min(
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c.p + c.d.length,
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otherC.p + otherC.d.length
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)
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const cIntersect = c.d.slice(intersectStart - c.p, intersectEnd - c.p)
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const otherIntersect = otherC.d.slice(
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intersectStart - otherC.p,
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intersectEnd - otherC.p
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)
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if (cIntersect !== otherIntersect) {
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throw new Error(
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'Delete ops delete different text in the same region of the document'
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)
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}
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if (newC.d !== '') {
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// This could be rewritten similarly to insert v delete, above.
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newC.p = transformPosition(newC.p, otherC)
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append(dest, newC)
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}
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}
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}
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}
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return dest
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}
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const invertComponent = function (c) {
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if (c.i != null) {
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return { d: c.i, p: c.p }
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} else {
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return { i: c.d, p: c.p }
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}
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}
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// No need to use append for invert, because the components won't be able to
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// cancel with one another.
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text.invert = op =>
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Array.from(op.slice().reverse()).map(c => invertComponent(c))
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if (typeof WEB !== 'undefined' && WEB !== null) {
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if (!exports.types) {
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exports.types = {}
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}
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// This is kind of awful - come up with a better way to hook this helper code up.
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bootstrapTransform(text, transformComponent, checkValidOp, append)
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// [] is used to prevent closure from renaming types.text
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exports.types.text = text
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} else {
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module.exports = text
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// The text type really shouldn't need this - it should be possible to define
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// an efficient transform function by making a sort of transform map and passing each
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// op component through it.
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require('./helpers').bootstrapTransform(
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text,
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transformComponent,
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checkValidOp,
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append
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)
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}
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