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/// Positional information about a start and end point in the text.
#[derive(Debug, PartialEq, Clone)]
pub struct Range {
  /// Start byte index of the node in the text.
  pub start: usize,
  /// End byte index of the node in the text.
  pub end: usize,
  /// Line of the start position of the node in the text.
  pub start_line: usize,
  /// Line of the end position of the node in the text.
  pub end_line: usize,
}

impl Range {
  /// Gets the end byte index minus the start byte index of the range.
  pub fn width(&self) -> usize {
    self.end - self.start
  }
}

/// Represents an object that has a range in the text.
pub trait Ranged {
  /// Gets the range.
  fn range(&self) -> &Range;

  /// Gets the byte index of the first character in the text.
  fn start(&self) -> usize {
    self.range().start
  }
  /// Gets the line number of the start position in the text.
  fn start_line(&self) -> usize {
    self.range().start_line
  }
  /// Gets the byte index after the last character in the text.
  fn end(&self) -> usize {
    self.range().end
  }
  /// Gets the line number of the end position in the text.
  fn end_line(&self) -> usize {
    self.range().end_line
  }
  /// Gets the text from the provided string.
  fn text<'a>(&self, text: &'a str) -> &'a str {
    &text[self.start()..self.end()]
  }
  /// Gets the start byte position.
  fn start_position(&self) -> Position {
    let range = self.range();
    Position::new(range.start, range.start_line)
  }
  /// Gets the end byte position.
  fn end_position(&self) -> Position {
    let range = self.range();
    Position::new(range.end, range.end_line)
  }
  /// Gets the end byte index minus the start byte index of the range.
  fn width(&self) -> usize {
    self.range().width()
  }
}

/// Ranged value that specifies a specific position in the file.
pub struct Position {
  pub range: Range,
}

impl Position {
  /// Creates a new position at the specified position and line.
  pub fn new(pos: usize, line: usize) -> Position {
    Position {
      range: Range {
        start: pos,
        end: pos,
        start_line: line,
        end_line: line,
      },
    }
  }
}

impl Ranged for Position {
  fn range(&self) -> &Range {
    &self.range
  }
}