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comparison .cms/lib/codemirror/src/model/chunk.js @ 0:78edf6b517a0 draft

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24.10
author Coffee CMS <info@coffee-cms.ru>
date Fri, 11 Oct 2024 22:40:23 +0000
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1 import { cleanUpLine } from "../line/line_data.js"
2 import { indexOf } from "../util/misc.js"
3 import { signalLater } from "../util/operation_group.js"
4
5 // The document is represented as a BTree consisting of leaves, with
6 // chunk of lines in them, and branches, with up to ten leaves or
7 // other branch nodes below them. The top node is always a branch
8 // node, and is the document object itself (meaning it has
9 // additional methods and properties).
10 //
11 // All nodes have parent links. The tree is used both to go from
12 // line numbers to line objects, and to go from objects to numbers.
13 // It also indexes by height, and is used to convert between height
14 // and line object, and to find the total height of the document.
15 //
16 // See also http://marijnhaverbeke.nl/blog/codemirror-line-tree.html
17
18 export function LeafChunk(lines) {
19 this.lines = lines
20 this.parent = null
21 let height = 0
22 for (let i = 0; i < lines.length; ++i) {
23 lines[i].parent = this
24 height += lines[i].height
25 }
26 this.height = height
27 }
28
29 LeafChunk.prototype = {
30 chunkSize() { return this.lines.length },
31
32 // Remove the n lines at offset 'at'.
33 removeInner(at, n) {
34 for (let i = at, e = at + n; i < e; ++i) {
35 let line = this.lines[i]
36 this.height -= line.height
37 cleanUpLine(line)
38 signalLater(line, "delete")
39 }
40 this.lines.splice(at, n)
41 },
42
43 // Helper used to collapse a small branch into a single leaf.
44 collapse(lines) {
45 lines.push.apply(lines, this.lines)
46 },
47
48 // Insert the given array of lines at offset 'at', count them as
49 // having the given height.
50 insertInner(at, lines, height) {
51 this.height += height
52 this.lines = this.lines.slice(0, at).concat(lines).concat(this.lines.slice(at))
53 for (let i = 0; i < lines.length; ++i) lines[i].parent = this
54 },
55
56 // Used to iterate over a part of the tree.
57 iterN(at, n, op) {
58 for (let e = at + n; at < e; ++at)
59 if (op(this.lines[at])) return true
60 }
61 }
62
63 export function BranchChunk(children) {
64 this.children = children
65 let size = 0, height = 0
66 for (let i = 0; i < children.length; ++i) {
67 let ch = children[i]
68 size += ch.chunkSize(); height += ch.height
69 ch.parent = this
70 }
71 this.size = size
72 this.height = height
73 this.parent = null
74 }
75
76 BranchChunk.prototype = {
77 chunkSize() { return this.size },
78
79 removeInner(at, n) {
80 this.size -= n
81 for (let i = 0; i < this.children.length; ++i) {
82 let child = this.children[i], sz = child.chunkSize()
83 if (at < sz) {
84 let rm = Math.min(n, sz - at), oldHeight = child.height
85 child.removeInner(at, rm)
86 this.height -= oldHeight - child.height
87 if (sz == rm) { this.children.splice(i--, 1); child.parent = null }
88 if ((n -= rm) == 0) break
89 at = 0
90 } else at -= sz
91 }
92 // If the result is smaller than 25 lines, ensure that it is a
93 // single leaf node.
94 if (this.size - n < 25 &&
95 (this.children.length > 1 || !(this.children[0] instanceof LeafChunk))) {
96 let lines = []
97 this.collapse(lines)
98 this.children = [new LeafChunk(lines)]
99 this.children[0].parent = this
100 }
101 },
102
103 collapse(lines) {
104 for (let i = 0; i < this.children.length; ++i) this.children[i].collapse(lines)
105 },
106
107 insertInner(at, lines, height) {
108 this.size += lines.length
109 this.height += height
110 for (let i = 0; i < this.children.length; ++i) {
111 let child = this.children[i], sz = child.chunkSize()
112 if (at <= sz) {
113 child.insertInner(at, lines, height)
114 if (child.lines && child.lines.length > 50) {
115 // To avoid memory thrashing when child.lines is huge (e.g. first view of a large file), it's never spliced.
116 // Instead, small slices are taken. They're taken in order because sequential memory accesses are fastest.
117 let remaining = child.lines.length % 25 + 25
118 for (let pos = remaining; pos < child.lines.length;) {
119 let leaf = new LeafChunk(child.lines.slice(pos, pos += 25))
120 child.height -= leaf.height
121 this.children.splice(++i, 0, leaf)
122 leaf.parent = this
123 }
124 child.lines = child.lines.slice(0, remaining)
125 this.maybeSpill()
126 }
127 break
128 }
129 at -= sz
130 }
131 },
132
133 // When a node has grown, check whether it should be split.
134 maybeSpill() {
135 if (this.children.length <= 10) return
136 let me = this
137 do {
138 let spilled = me.children.splice(me.children.length - 5, 5)
139 let sibling = new BranchChunk(spilled)
140 if (!me.parent) { // Become the parent node
141 let copy = new BranchChunk(me.children)
142 copy.parent = me
143 me.children = [copy, sibling]
144 me = copy
145 } else {
146 me.size -= sibling.size
147 me.height -= sibling.height
148 let myIndex = indexOf(me.parent.children, me)
149 me.parent.children.splice(myIndex + 1, 0, sibling)
150 }
151 sibling.parent = me.parent
152 } while (me.children.length > 10)
153 me.parent.maybeSpill()
154 },
155
156 iterN(at, n, op) {
157 for (let i = 0; i < this.children.length; ++i) {
158 let child = this.children[i], sz = child.chunkSize()
159 if (at < sz) {
160 let used = Math.min(n, sz - at)
161 if (child.iterN(at, used, op)) return true
162 if ((n -= used) == 0) break
163 at = 0
164 } else at -= sz
165 }
166 }
167 }