74 lines
2.2 KiB
TypeScript
74 lines
2.2 KiB
TypeScript
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// 极简行级差异：Nginx 配置通常只有几十行，用 LCS 就够，不为此引入第三方 diff 依赖。
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export interface DiffLine {
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kind: 'same' | 'add' | 'del'
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text: string
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oldLine?: number
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newLine?: number
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}
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// maxDiffCells 限制 LCS 表大小：超长文本（例如整份日志误粘进来）退化为「整体替换」，
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// 避免 O(n*m) 的表把页面卡死。
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const maxDiffCells = 250_000
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export function diffLines(fromText: string, toText: string): DiffLine[] {
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const from = splitLines(fromText)
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const to = splitLines(toText)
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if (from.length * to.length > maxDiffCells) {
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return [
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...from.map((text, index) => ({ kind: 'del' as const, text, oldLine: index + 1 })),
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...to.map((text, index) => ({ kind: 'add' as const, text, newLine: index + 1 })),
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]
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}
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// dp[i][j] = from[i..] 与 to[j..] 的最长公共子序列长度
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const dp: number[][] = Array.from({ length: from.length + 1 }, () => new Array<number>(to.length + 1).fill(0))
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for (let i = from.length - 1; i >= 0; i -= 1) {
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for (let j = to.length - 1; j >= 0; j -= 1) {
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dp[i][j] = from[i] === to[j] ? dp[i + 1][j + 1] + 1 : Math.max(dp[i + 1][j], dp[i][j + 1])
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}
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}
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const out: DiffLine[] = []
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let i = 0
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let j = 0
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while (i < from.length && j < to.length) {
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if (from[i] === to[j]) {
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out.push({ kind: 'same', text: from[i], oldLine: i + 1, newLine: j + 1 })
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i += 1
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j += 1
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} else if (dp[i + 1][j] >= dp[i][j + 1]) {
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out.push({ kind: 'del', text: from[i], oldLine: i + 1 })
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i += 1
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} else {
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out.push({ kind: 'add', text: to[j], newLine: j + 1 })
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j += 1
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}
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}
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while (i < from.length) {
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out.push({ kind: 'del', text: from[i], oldLine: i + 1 })
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i += 1
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}
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while (j < to.length) {
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out.push({ kind: 'add', text: to[j], newLine: j + 1 })
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j += 1
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}
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return out
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}
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export function diffStats(lines: DiffLine[]): { added: number; removed: number } {
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let added = 0
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let removed = 0
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for (const line of lines) {
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if (line.kind === 'add') added += 1
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else if (line.kind === 'del') removed += 1
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}
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return { added, removed }
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}
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function splitLines(text: string): string[] {
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if (text === '') return []
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return text.replace(/\r\n/g, '\n').replace(/\n+$/, '').split('\n')
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}
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