#displaytext

#Installation

> moon add moonbit-community/displaytext

#API

#DisplayText(s : String, cjk? : Bool = false) -> DisplayText

• s: text that the caller already wants to measure and navigate as one run
• cjk: when true, ambiguous-width characters are treated as wide

#split_lines(s : @string.View, cjk? : Bool = false) -> Array[DisplayText]

• s: plain text that may contain hard line breaks
• cjk: when true, ambiguous-width characters are treated as wide

• total display width with width()
• legal textual boundaries with start(), end(), next(), and prev()
• conversion from textual boundaries to columns with display_position()
• conversion from display columns to textual boundaries with textual_position_at_or_before() and textual_position_at_or_after()
• zero-copy text views with view()
• terminal-cell truncation with truncate()

#Usage

///|
test {
  let lines = @displaytext.split_lines("a你好b\nnext")
  let line = lines[0]

  // Whole-line display width.
  assert_eq(line.width(), 6)

  // Move by legal textual positions, not UTF-16 code units.
  let after_a = line.next(line.start()).unwrap()
  let after_ni = line.next(after_a).unwrap()
  assert_eq(line.display_position(after_ni).column(), 3)

  // Convert a display column inside a wide character back to text boundaries.
  let middle = @displaytext.DisplayPosition::new(column=2)
  assert_eq(
    line.view(line.start(), line.textual_position_at_or_before(middle)),
    "a",
  )
  assert_eq(
    line.view(line.start(), line.textual_position_at_or_after(middle)),
    "a你",
  )

  // Truncate without cutting through a display unit.
  assert_eq(line.truncate(4), "a你…")
}

#Consumer-Owned Wrapping

///|
test {
  let line = @displaytext.DisplayText::DisplayText("ab你好")
  let remaining = @displaytext.DisplayPosition::new(column=3)
  let end = line.textual_position_at_or_before(remaining)

  assert_eq(line.view(line.start(), end), "ab")
}

#Concepts

#Scope

#Testing

> moon test

#License