oppi.li
source dump of claude code
1import type { Diff } from './frame.js'
2
3/**
4 * Optimize a diff by applying all optimization rules in a single pass.
5 * This reduces the number of patches that need to be written to the terminal.
6 *
7 * Rules applied:
8 * - Remove empty stdout patches
9 * - Merge consecutive cursorMove patches
10 * - Remove no-op cursorMove (0,0) patches
11 * - Concat adjacent style patches (transition diffs — can't drop either)
12 * - Dedupe consecutive hyperlinks with same URI
13 * - Cancel cursor hide/show pairs
14 * - Remove clear patches with count 0
15 */
16export function optimize(diff: Diff): Diff {
17 if (diff.length <= 1) {
18 return diff
19 }
20
21 const result: Diff = []
22 let len = 0
23
24 for (const patch of diff) {
25 const type = patch.type
26
27 // Skip no-ops
28 if (type === 'stdout') {
29 if (patch.content === '') continue
30 } else if (type === 'cursorMove') {
31 if (patch.x === 0 && patch.y === 0) continue
32 } else if (type === 'clear') {
33 if (patch.count === 0) continue
34 }
35
36 // Try to merge with previous patch
37 if (len > 0) {
38 const lastIdx = len - 1
39 const last = result[lastIdx]!
40 const lastType = last.type
41
42 // Merge consecutive cursorMove
43 if (type === 'cursorMove' && lastType === 'cursorMove') {
44 result[lastIdx] = {
45 type: 'cursorMove',
46 x: last.x + patch.x,
47 y: last.y + patch.y,
48 }
49 continue
50 }
51
52 // Collapse consecutive cursorTo (only the last one matters)
53 if (type === 'cursorTo' && lastType === 'cursorTo') {
54 result[lastIdx] = patch
55 continue
56 }
57
58 // Concat adjacent style patches. styleStr is a transition diff
59 // (computed by diffAnsiCodes(from, to)), not a setter — dropping
60 // the first is only sound if its undo-codes are a subset of the
61 // second's, which is NOT guaranteed. e.g. [\e[49m, \e[2m]: dropping
62 // the bg reset leaks it into the next \e[2J/\e[2K via BCE.
63 if (type === 'styleStr' && lastType === 'styleStr') {
64 result[lastIdx] = { type: 'styleStr', str: last.str + patch.str }
65 continue
66 }
67
68 // Dedupe hyperlinks
69 if (
70 type === 'hyperlink' &&
71 lastType === 'hyperlink' &&
72 patch.uri === last.uri
73 ) {
74 continue
75 }
76
77 // Cancel cursor hide/show pairs
78 if (
79 (type === 'cursorShow' && lastType === 'cursorHide') ||
80 (type === 'cursorHide' && lastType === 'cursorShow')
81 ) {
82 result.pop()
83 len--
84 continue
85 }
86 }
87
88 result.push(patch)
89 len++
90 }
91
92 return result
93}