Initial commit

2026-03-06 22:56:13 +08:00
commit 54d1097b41
273 changed files with 92457 additions and 0 deletions
--- a/src/lib/line-change-stats.ts
+++ b/src/lib/line-change-stats.ts
@@ -0,0 +1,151 @@
+export interface LineChangeStats {
+  additions: number
+  deletions: number
+}
+
+const MAX_LCS_MATCH_PAIRS = 200_000
+
+export function splitNormalizedLines(text: string): string[] {
+  if (!text) return []
+  const lines = text.split("\n")
+  if (lines.length > 0 && lines[lines.length - 1] === "") {
+    lines.pop()
+  }
+  return lines
+}
+
+function contiguousChangedLineStats(
+  oldLines: string[],
+  newLines: string[]
+): LineChangeStats {
+  let prefix = 0
+  while (
+    prefix < oldLines.length &&
+    prefix < newLines.length &&
+    oldLines[prefix] === newLines[prefix]
+  ) {
+    prefix += 1
+  }
+
+  let suffix = 0
+  while (
+    suffix < oldLines.length - prefix &&
+    suffix < newLines.length - prefix &&
+    oldLines[oldLines.length - 1 - suffix] ===
+      newLines[newLines.length - 1 - suffix]
+  ) {
+    suffix += 1
+  }
+
+  return {
+    additions: Math.max(0, newLines.length - prefix - suffix),
+    deletions: Math.max(0, oldLines.length - prefix - suffix),
+  }
+}
+
+function lowerBound(values: number[], target: number): number {
+  let left = 0
+  let right = values.length
+  while (left < right) {
+    const mid = left + ((right - left) >> 1)
+    if (values[mid] < target) {
+      left = mid + 1
+    } else {
+      right = mid
+    }
+  }
+  return left
+}
+
+function exceedsLcsPairBudget(oldLines: string[], newLines: string[]): boolean {
+  if (oldLines.length === 0 || newLines.length === 0) return false
+
+  const oldFreq = new Map<string, number>()
+  for (const line of oldLines) {
+    oldFreq.set(line, (oldFreq.get(line) ?? 0) + 1)
+  }
+
+  const newFreq = new Map<string, number>()
+  for (const line of newLines) {
+    newFreq.set(line, (newFreq.get(line) ?? 0) + 1)
+  }
+
+  let pairs = 0
+  for (const [line, oldCount] of oldFreq) {
+    const newCount = newFreq.get(line)
+    if (!newCount) continue
+    pairs += oldCount * newCount
+    if (pairs > MAX_LCS_MATCH_PAIRS) return true
+  }
+
+  return false
+}
+
+function lcsLengthByLine(oldLines: string[], newLines: string[]): number {
+  const positions = new Map<string, number[]>()
+  for (let i = 0; i < newLines.length; i += 1) {
+    const line = newLines[i]
+    const bucket = positions.get(line)
+    if (bucket) {
+      bucket.push(i)
+    } else {
+      positions.set(line, [i])
+    }
+  }
+
+  const lis: number[] = []
+  for (const line of oldLines) {
+    const bucket = positions.get(line)
+    if (!bucket || bucket.length === 0) continue
+
+    for (let i = bucket.length - 1; i >= 0; i -= 1) {
+      const pos = bucket[i]
+      const at = lowerBound(lis, pos)
+      if (at === lis.length) {
+        lis.push(pos)
+      } else {
+        lis[at] = pos
+      }
+    }
+  }
+
+  return lis.length
+}
+
+export function estimateChangedLineStats(
+  oldText: string,
+  newText: string
+): LineChangeStats {
+  const oldLines = splitNormalizedLines(oldText)
+  const newLines = splitNormalizedLines(newText)
+
+  if (oldLines.length === 0 && newLines.length === 0) {
+    return { additions: 0, deletions: 0 }
+  }
+  if (oldLines.length === 0) {
+    return { additions: newLines.length, deletions: 0 }
+  }
+  if (newLines.length === 0) {
+    return { additions: 0, deletions: oldLines.length }
+  }
+
+  if (exceedsLcsPairBudget(oldLines, newLines)) {
+    return contiguousChangedLineStats(oldLines, newLines)
+  }
+
+  const lcs = lcsLengthByLine(oldLines, newLines)
+  return {
+    additions: Math.max(0, newLines.length - lcs),
+    deletions: Math.max(0, oldLines.length - lcs),
+  }
+}
+
+export function countUnifiedDiffLineChanges(text: string): LineChangeStats {
+  let additions = 0
+  let deletions = 0
+  for (const line of text.split("\n")) {
+    if (line.startsWith("+") && !line.startsWith("+++")) additions += 1
+    if (line.startsWith("-") && !line.startsWith("---")) deletions += 1
+  }
+  return { additions, deletions }
+}