#Rope-MoonBit

#Features

• O(log n) insert and remove at arbitrary positions
• O(n) construction from a string or via RopeBuilder
• Correct Unicode support: char indices and UTF-8 byte offsets
• Line/char index conversions for editor protocol (LSP/DAP) compatibility
• Lazy iterators for chunks, chars, and lines
• Slice views without copying
• Targets: wasm-gc, native, js

#Installation

{
  "deps": {
    "Teddy-Yangjiale/rope": "0.1.0"
  }
}

moon update
moon install

#Quick Start

fn main {
  // Create a rope from a string
  let r = Rope::from_str("Hello, world!")
  println(r.len_chars())   // 13
  println(r.len_bytes())   // 13 (UTF-8 bytes)
  println(r.len_lines())   // 1

  // Efficient insert and remove
  let r2 = r.insert(7, "beautiful ")
  println(r2.to_string())  // "Hello, beautiful world!"

  let r3 = r2.remove(7, 17)
  println(r3.to_string())  // "Hello, world!"

  // Split and concat
  let (left, right) = r.split(7)
  println(left.to_string())   // "Hello, "
  println(right.to_string())  // "world!"
  let rejoined = left.concat(right)
  println(rejoined.to_string())  // "Hello, world!"
}

#API Reference

#Construction

#Queries

#Editing

#Index Conversion

#Slices

#Iterators

#Equality

#RopeBuilder Example

fn load_file_lines(lines: Array[String]) -> Rope {
  let builder = RopeBuilder::new()
  for line in lines {
    builder.push(line)
    builder.push("\n")
  }
  builder.build()
}

#Unicode Example

fn unicode_demo {
  let r = Rope::from_str("你好世界")
  println(r.len_chars())   // 4 (code points)
  println(r.len_bytes())   // 12 (UTF-8 bytes)
  println(r.char_at(0))    // '你'
  println(r.char_to_byte(1))  // 3 (second char starts at byte 3)
}

#Running the Example

git clone https://github.com/Teddy-Yangjiale/Rope-Moonbit
cd Rope-Moonbit
moon run examples

#Running Tests

moon test

#Design

• Leaves hold UTF-16 string chunks (up to 256 code units each)
• Internal nodes hold up to 8 children with pre-computed metrics (bytes, chars, newlines)
• All operations produce new nodes via structural sharing (persistent/immutable style)

#License