#MoonBit Diff

A dependency-free, Unicode-safe text diff and Unified Diff library for MoonBit.

#功能概览

#安装

moon add pei0331/moonbit_diff@0.5.0

import {
  "pei0331/moonbit_diff" @diff,
}

#快速开始

let edits = @diff.diff("Moon😀 diff", "Moon🌕 patch")
let compacted = @diff.compact(edits)

for edit in compacted {
  match edit {
    Equal(text) => println("Equal(\{text})")
    Delete(text) => println("Delete(\{text})")
    Insert(text) => println("Insert(\{text})")
  }
}

Equal(Moon)
Delete(😀)
Insert(🌕)
Equal( )
Delete(diff)
Insert(patch)

#文本重建与统计

let edits = @diff.diff("A😀bc", "A😀🌕d")

assert_eq!(@diff.reconstruct_old(edits), "A😀bc")
assert_eq!(@diff.reconstruct_new(edits), "A😀🌕d")

let summary = @diff.stats(edits)
println("equal: \{summary.equal_count}")
println("deleted: \{summary.delete_count}")
println("inserted: \{summary.insert_count}")

#应用与反转编辑脚本

let old_text = "Moon😀 diff"
let new_text = "Moon🌕 patch"
let edits = @diff.diff(old_text, new_text) |> @diff.compact

match @diff.apply(edits, old_text) {
  Ok(result) => println(result)
  Err(_) => println("source and edit script do not match")
}

let reverse_edits = @diff.invert(edits)
assert_eq!(@diff.apply(reverse_edits, new_text), Ok(old_text))

#Unified Diff

#简单全量输出

let patch = @diff.unified_diff(
  "one\ntwo\nthree",
  "one\n2\nthree",
)
println(patch)

--- old
+++ new
@@ -1,3 +1,3 @@
 one
-two
+2
 three

#自定义上下文与多 hunk

let patch = @diff.unified_diff_with_context(
  old_source,
  new_source,
  "src/before.mbt",
  "src/after.mbt",
  3,
)

#标准 EOF 换行语义

let patch = @diff.unified_diff_standard(
  "value=old",
  "value=new\n",
  "a/config.txt",
  "b/config.txt",
  3,
)

--- a/config.txt
+++ b/config.txt
@@ -1,1 +1,1 @@
-value=old
\ No newline at end of file
+value=new

#Unicode 语义

#API 参考

pub(all) enum EditOp {
  Equal(String)
  Delete(String)
  Insert(String)
}

pub(all) enum ApplyError {
  SourceExhausted(Int, String)
  SourceMismatch(Int, String, String)
  SourceNotFullyConsumed(Int, String)
}

pub(all) struct DiffStats {
  equal_count : Int
  delete_count : Int
  insert_count : Int
}

pub fn diff(String, String) -> Array[EditOp]
pub fn compact(Array[EditOp]) -> Array[EditOp]
pub fn reconstruct_old(Array[EditOp]) -> String
pub fn reconstruct_new(Array[EditOp]) -> String
pub fn stats(Array[EditOp]) -> DiffStats
pub fn apply(Array[EditOp], String) -> Result[String, ApplyError]
pub fn invert(Array[EditOp]) -> Array[EditOp]
pub fn unified_diff(String, String) -> String
pub fn unified_diff_with_context(
  String,
  String,
  String,
  String,
  Int,
) -> String
pub fn unified_diff_standard(String, String, String, String, Int) -> String

moon info

#可运行示例

moon run examples/basic

#算法与复杂度

• 字符级和行级差异共用 Myers 最短编辑路径算法。
• 设新旧序列总长度为 N+M，最短编辑距离为 D，时间复杂度为 O((N+M)*D)，路径回溯空间复杂度为 O((N+M)*D)。
• 当修改量远小于文本长度时，D 较小，不再分配完整的 N*M LCS 矩阵。
• 最坏情况下 D 接近 N+M，时间和 trace 空间仍可能达到二次规模。
• 字符级 API 会先剥离公共前缀和后缀，因此局部修改通常只需处理较短的中间区间。
• 当前实现适合配置文件、源码片段、日志片段和中小型文本。
• 对超大文件或完全不同的长文本，建议先按块或按行缩小范围，避免保存过大的路径 trace。
• Unified Diff 是渲染输出 API，当前不提供补丁解析或补丁应用功能。

#开发与验证

moon fmt --check
moon check --deny-warn
moon build --target wasm-gc
moon test --target wasm-gc
moon run examples/basic

#仓库与发布

• GitHub: https://github.com/pei0331/moon-diff
• GitLink: https://gitlink.org.cn/peiyuran/moon-diff
• Mooncakes: pei0331/moonbit_diff

#License